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Nanomaterials for radioactive wastewater decontamination
Abstract
Radioactive waste is a byproduct of nuclear power generation and applications of various radioactive materials in many fields. This waste has been strictly regulated as a highly hazardous material to all forms of life and the environment. The technologies currently adopted for managing radioactive waste are mainly based on segregation and storage. Ideally radioactive waste should be isolated from entering the environment, but there has been slow progress toward sustainable waste management. Nanomaterials, with the unique physical and chemical properties, such as nano-size effect, large specific surface area, high reactivity and selectivity, have become a new type of materials for radioactive wastewater decontamination. Therefore, this review aims to provide an comprehensive overview and analysis of the new generation of nanomaterials which have been demonstrated effective for radioactive wastewater decontamination, including carbon-based nanomaterials, metal nanoparticles, nanosized metal oxides, metal sulfides, nano-sized natural materials, layered double hydroxides, hydroxyapatite nanoparticles, metal-organic frameworks, cellulose nanomaterials, biogenic nanocomposites, etc. Although many different types of nanomaterials have been developed, their engineering feasibility toward radioactive wastewater decontamination has not yet been demonstrated at real large-scale applications. Lastly, the challenges associated with the applications of nanomaterials for radioactive wastewater decontamination were discussed in detail, while shedding light on future research direction.
... The findings revealed that Sr 2+ was the predominant species in solution within the pH range of 1-10, with the onset of Sr(OH) − formation observed at pH values exceeding 10. In engineering applications, the pH range for most low-level waste liquids typically lies between 3-9, where Sr 2+ remains soluble [43]. Consequently, adsorption experiments were conducted across this pH range. ...
... The findings revealed that Sr 2+ was the predominant species in solution within the pH range of 1-10, with the onset of Sr(OH)⁻ formation observed at pH values exceeding 10. In engineering applications, the pH range for most low-level waste liquids typically lies between 3-9, where Sr 2+ remains soluble [43]. Consequently, adsorption experiments were conducted across this pH range. ...
The efficient segregation of radioactive nuclides from low-level radioactive liquid waste (LLRW) is paramount for nuclear emergency protocols and waste minimization. Here, we synthesized Na3FePO4CO3 (NFPC) via a one-pot hydrothermal method and applied it for the first time to the selective separation of Sr2+ from simulated LLRW. Static adsorption experimental results indicated that the distribution coefficient Kd remained above 5000 mL·g−1, even when the concentration of interfering ions was more than 40 times that of Sr2+. Furthermore, the removal efficiency of Sr2+ showed no significant change within the pH range of 4 to 9. The adsorption of Sr2+ fitted the pseudo-second-order kinetic model and the Langmuir isotherm model, with an equilibrium time of 36 min and a maximum adsorption capacity of 99.6 mg·g−1. Notably, the adsorption capacity was observed to increment marginally with an elevation in temperature. Characterization analyses and density functional theory (DFT) calculations elucidated the adsorption mechanism, demonstrating that Sr2+ initially engaged in an ion exchange reaction with Na+. Subsequently, Sr2+ coordinated with four oxygen atoms on the NFPC (100) facet, establishing a robust Sr-O bond via orbital hybridization.
... The byproduct of nuclear power generation is a hazardous radioactive waste that poses a serious threat to all forms of life as well as the environment and thus, should be strictly regulated. Two different disposal strategies are applied in nuclear waste management, these are: (1) the geological disposal of the spent fuel after a few decades of wet or dry storages, and (2) the spent fuel storage that is reprocessed with aqueous dissolution, and conditioned in borosilicate glass before the geological disposal (Nath, 2018;Zhang & Liu, 2020). ...
... The spectrum of possible applications of carbon nanotubes includes treatment of liquid effluents from nuclear plants, environmental remediation of contaminated sites, waste immobilization for final disposal. Carbon nanotubes are also used as an ion exchanger to remove radioactive cesium ions from nuclear wastewater (Belloni et al., 2009;Shi et al., 2012;Zhang & Liu, 2020). ...
The rapid technological advancement of the manufacturing sector over the past few decades inevitably led to the rise of Industry 4.0. It has the potential to significantly alter how globalisation is practiced in the production and consumption of products and services across international markets. In this chapter, we'll take a closer look at the rise of Industry 4.0 and the new technical architecture that underpins it, as well as the benefits it's expected to bring.In addition, how we may use technology to fortify a company's competitiveness and shield it from the perils of this transformation. The new global division of labour, the worldwide supply chain, and the global value chain will all be profoundly affected by this multifaceted technology, as evidenced by a thorough examination of the relevant literature. It will alter the competitive landscape by shifting the advantage away from large corporations and toward small and medium-sized enterprises (SMEs) in emerging markets and developed markets. As human and technological skills advance quickly, businesses may be able to profit.
... The byproduct of nuclear power generation is a hazardous radioactive waste that poses a serious threat to all forms of life as well as the environment and thus, should be strictly regulated. Two different disposal strategies are applied in nuclear waste management, these are: (1) the geological disposal of the spent fuel after a few decades of wet or dry storages, and (2) the spent fuel storage that is reprocessed with aqueous dissolution, and conditioned in borosilicate glass before the geological disposal (Nath, 2018;Zhang & Liu, 2020). ...
... The spectrum of possible applications of carbon nanotubes includes treatment of liquid effluents from nuclear plants, environmental remediation of contaminated sites, waste immobilization for final disposal. Carbon nanotubes are also used as an ion exchanger to remove radioactive cesium ions from nuclear wastewater (Belloni et al., 2009;Shi et al., 2012;Zhang & Liu, 2020). ...
Waste management represents a challenge due to the rapid increase in waste production and the emerging of new waste types. Overcoming the issue involves using innovative technologies such as nanotechnology. Nanotechnology uses nanomaterials, which are materials that have at least one dimension less than 100 nm. Due to their small size, these materials increase reactivity in processes such as adsorption and oxidation/reduction. The application of nanotechnologies is significant in the production of new materials to replace current raw materials, and in providing novel solutions for waste recycling and disposal. Furthermore, nanofiltration is effective in the treatment of metals, toxic waste, and nonbiodegradable materials of leachate. Nanomaterials, however, represent a safety risk for the environment, and a serious threat to human health due to their small size and long suspension time. This chapter deals with the use of nanotechnology in waste management, including reduction, recycling, treatment, and disposal phases.
... Yılmaz D et al. [20] found that nanomaterials offered a wide range of possibilities for producing the newest radioactive wastewater decontamination technology [21]. However, the toxicity features and expansive analysis requirements in addition to the need of skilled human resources hinder the actual/specific application of these nanomaterials [22]. ...
... The thermodynamic parameters such as standard Gibbs free energy (∆G o ), enthalpy (∆H o ), and entropy (∆S o ) were used to determine the spontaneity, nature, and adsorbent suitability of the adsorption process [41]. Equations (20,21,22) were used to calculate thermodynamic parameters using temperature-dependent adsorption isotherms. ...
A novel nanocomposite was prepared by hybridizing polyacrylic acid/maleic acid with nano copper oxide (PAACMA/CuO) for the sorption of ⁶⁰ Co (II) and ¹⁵²⁺¹⁵⁴ Eu (III) radionuclides from an aqueous solution. Nano-CuO was biochemically produced by hydrolysing its salt in the presence of the Aspergillus terreus fungus. The PAACMA/CuO nanocomposite was characterized using a variety of analytical techniques. The optimum sorption conditions (pH 4.5 for ⁶⁰ Co and pH 3.53 for ¹⁵²⁺¹⁵⁴ Eu, 24 h of equilibrium time at 20 o C) were applied. The kinetic mechanism of the sorption reaction was controlled by pseudo second order based on residual charts, coefficient of determination (R ² ), and corrected Akaike information Criterion (AIC c ). The sorption reaction mechanism was controlled by Langmuir model for linear regression using the coefficient of determination and the Dubinin-Radushkevich D-R model for the AIC c and residual plots error functions. The reaction mechanism throughout non-linear regression was controlled by the D-R model due to the coefficient of determination, AIC c , and residual charts. The PAACMA/CuO nanocomposite had a mono-layer adsorption capacity of 11.04 mg g − 1 for Co (II) and 21.54 mg g − 1 for Eu (III). According to desorption studies, Co (II) and Eu (III) could be recovered by 0.1 mol L − 1 EDTA with efficiencies 55.46% and 95.044%, respectively. According to thermodynamic studies, the sorption of Co (II) and Eu (III) on the prepared composite was endothermic and spontaneous.
... The use of adsorption for the pre-concentration/ separation of radionuclides from nuclear waste solutions has been widely demonstrated, as many different synthetic and natural solid-phase adsorbents have been employed in radioactive waste management. These include peat [7,8], silica [9,10], alumina [11,12], activated carbon [13,14], clay minerals [15,16], composite ion exchangers [17], zeolites [18], nanoparticles [19], carbon nanotubes [20], and composites [21,22]. The adsorption performance of these solid-phase adsorbents is very high, and they have also demonstrated remarkable resistance to radiation damage. ...
This work is interested in the sorption and separation of 131 Ba, 109 Cd, 152+154 Eu, and 97 Zr from radioactive solutions onto barium molybdenum titanate loaded on carboxy methyl cellulose (BaMoTi@CMC) composites. In this work, different samples of BaMoTi@CMC composites were fabricated by the co-precipitation method and characterized using different analytical tools such as X-ray diffraction (XRD), attenuated total reflectance (ATR), and scanning electron microscope (SEM). The batch sorption investigations on 131 Ba, 109 Cd, 152+154 Eu, and 97 Zr include the influence of time, pH, and metal ion concentrations. The data reveal that S-3 has higher sorption efficiency than S-2 under all conditions. Isotherm is studied by Langmuir and Freundlich models. Binary systems data confirm that Cd(II), Ba(II), and Zr(IV) can be separated from Cd-Eu, Ba-Eu, and Zr-Eu binary systems using S-2 and S-3 at different pHs. Finally, the data prove that Zr(IV) and Ba(II) can be easily separated from tertiary systems (Zr-Ba-Cd) onto S-2 and S-3 at pH 2.
... In the era of searching for sustainable energy resources, nuclear energy is considered an important renewable energy alternative worldwide due to its clean nature and negligible greenhouse gas emissions [1]. The use of nuclear technologies is fast growing with applications in various areas like the medicinal sector, industrial sector, mining industries, research sector, etc. [2,3]. ...
An environmentally benign aqueous two phase system has been developed for the separation of 108mAg from ¹⁵²Eu and ⁶⁰Co using polyethylene glycol/salt system. Twelve salts (nine inorganic, three organic) and PEG 4000 were chosen to form the ATPS out of which, the best separation was observed for 3 mL 2 mol·dm⁻³ K3PO4: 3 mL PEG 4000 followed by 3 mL 2 mol·dm⁻³ Na2SO4: 3 mL PEG 4000. In both cases, silver was preferentially extracted in the PEG rich phase. The separation factors achieved were SAg/Co = 2.11 × 10³ and SAg/Eu = 2.79 × 10² in the case of 2 mol·dm⁻³ K3PO4: PEG 4000 combination.
... There is no doubt about impact in water sources due to the mining effluents (Srivastava et al. 2020;Pereira et al. 2021a, b;Fleming et al. 2022;Guerrero et al. 2023). Therefore, there is an effort by the scientific community to offer ever better management for this environmental issue (Zhang & Liu 2020;Miller et al. 2021;Dinis and Fiúza 2021;Adeola et al. 2022). In this context, new technologies have been developed in recent years for the purpose of removal efficiently heavy metals (Ragheb et al. 2022), radionuclides (Baeza et al. 2017;Banala et al. 2021;Nezhad et al. 2021;Li et al. 2021;Kutsevol et al. 2021;Fu et al. 2022;Lei et al. 2022;Pan et al. 2022) or both ) from different wastewater. ...
Uranium mining causes several radiological impacts on the surrounding environment, notably in the water bodies, mainly due to the release of long half-life radionuclides from the 238 U and 232 Th series. The Ore Treatment Unit, an old uranium mine undergoing decommissioning, has three points of liquid effluent release (#014, #025, and #076). For current study, 78 samples of water were collected at #014, 33 samples at #025, and 63 samples at #076. The radionuclides were analyzed by gross alpha count, gross beta count, and by arsenazo spectrophotometry. Analyses were carried out using the radiological water quality criterion established by World Health Organization and other organizations, together with the Brazilian legislation, to assess if the released effluents may be used unrestrictedly by the individuals of the public. At #014, the mean values of activity concentration (AC), in Bq·L −1 , were as follows: U nat = 0.107, 226 Ra = 0.035, 210 Pb = 0.031, 232 Th = 0.007, and 228 Ra = 0.049. At #025 the mean values of AC, in Bq·L −1 , were as follows: U nat = 0.086, 226 Ra = 0.015, 210 Pb = 0.028, 232 Th = 0.006, and 228 Ra = 0.032. Finally, at point #076, the mean AC values, in Bq·L −1 , were as follows: U nat = 3.624, 226 Ra = 0.074, 210 Pb = 0.054, 232 Th = 0.013, and 228 Ra = 0.069. The current study showed that natural radionuclides were not in secular equilibrium. Despite uranium presented its values outside the limits of guidance levels, it can be state that the unrestricted use of effluents released in the three water bodies is authorized from the radiological point of view. In terms of dose rate, the releases at three points were within the radiological limits of potability. On the other hand, in an additional analysis, #76 presented chemical toxicity above the authorized value, pointing the need of restricted use of water from the point of view of chemical toxicity.
... With the increasing demand for energy in modern society, nuclear energy has become one of the most important nonrenewable energy worldwide [1][2][3][4][5]. 90 Sr is the product of 235 U nuclear fission, and it is considered one of the most dangerous radionuclides owing to its long half-life, high fission yield, and high solubility in solution [6][7][8]. ...
Strontium, the main component of radioactive nuclear wastewater, is characterized by a high fission yield and an extended half-life. It is easily absorbed by the human body, thus greatly threatening the environment and the human body. In this study, a mesoporous composite phase sodium superionic conductor (NVP@NMP) was synthesized by the droplet template method, and the rapid capture of Sr2+ from wastewater was achieved by constructing a nano-heterogeneous interface to increase the ion diffusion rate. NVP@NMP showed efficient and rapid removal of strontium ions in adsorption kinetics, isothermal adsorption, solution pH, and interfering ions concentration tests. Especially the equilibrium time of 2 min for strontium absorption by NVP@NMP and a maximum theoretical adsorption capacity of 361.36 mg/g. The adsorption process was spontaneous, endothermic, and feasible. At higher concentrations of other competing ions (Na, K, Ca, Mg, and Cs), the adsorbent exhibited higher selectivity towards Sr2+.TEM, XPS, and XRD analyses revealed that ion exchange was the main mechanism for the NVP@NMP ultrafast adsorption of Sr2+. In this research, we investigated the feasibility of ultrafast strontium capture by sodium superionic conductor structured phosphates and explained the ultrafast strontium adsorption mechanism of NASICON materials through XPS.
... With the development of the nuclear industry, large quantities of wastewater containing a considerable amount of actinides (such as uranium, thorium, and plutonium, etc.) continue to be a great concern worldwide [1], especially since the Fukushima Daiichi nuclear accident. Removal of actinides from nuclear wastewater is crucial to secure public health and environmental safety due to their strong radioactivity and high chemical toxicity [2]. ...
Tetravalent metal (e.g., Zr4+, Hf4+) phosphonate frameworks featuring remarkable chemical and radiolytic
stabilities have been newly utilized as high-performing adsorbents for actinide in harsh solutions. Nevertheless,
the practical applications have been impeded by the as-synthesized powder form that is not compatible with
continuous actinide recovery or removal. Herein, we incorporate hafnium phosphonate (HfP) fine powder into
polyacrylonitrile (PAN) via a simple and economical electrospinning technique, engendering a stable and hydrophilic nanofibrous membrane with the first-rank permeate flux for the potential treatment of a large volume
of actinide-containing wastewater. This composite membrane can capture more than 90% Th(IV) at ppm level
and 95% Pu(IV) and 90% Np(V) at tracer amount level in strong acidic solutions, which retains the excellent
adsorption efficacy of HfP powder. Besides, it has a breakthrough volume larger than 880 mL for Th(IV) and 760
mL for U(VI) at the ppb level under a high permeate flux of 785 ± 11.2 L⋅m-2⋅h-1, representing one of the top
nanofibrous membranes for the dynamic removal of actinides. This work will pave an avenue for fabricating
highly efficient and stable adsorptive membranes, which are promising candidates for capturing actinides from
large-volume of acidic nuclear wastewater.
... Carbonaceousbased sorption technologies are an alternate way for eliminating harmful cation metals from wastewater [61]. Various researchers have discussed from time to time about the hazardous nature of radioactive waste and showed concern for its removal strategies [62,63]. Here we summarize the synthesis strategies used for GO, biochar, and activated carbon for the removal of toxic U(VI) metal from wastewater. ...
Carbon-based adsorbents such as activated carbon, biochar, and graphene materials are the most promising candidates for removing uranium from an aqueous solution. These materials could acquire different surface charges under different pH conditions and therefore are capable of adsorbing diverse uranium species from water. Another significant aspect of carbon-based adsorbents is their tunable surface characteristic to promote the targeted removal of uranium ions. In this review, we have summarized recent studies based on the strategies used for uranium species removal using afore mentioned carbon-based adsorbents. Different techniques used to prepare such adsorbents for the effective removal of uranium from wastewater has been discussed focusing the surface functionalization protocols. Discussions has been furnished on the key mechanisms involved in the uranium removal using the highlighted adsorbentswith reference to adsorption kinetics and isotherm models. The performance of various carbon-based adsorbents has been compared in terms of partition coefficient to assess their usefulness towards uranium removal applications. Further, a concise summary on DFT analysis has been supplied to elucidate uranium removal mechanisms by various carbon adsorbents. It is expected that this article will address the literature gapin the current status of carbon-based adsorbents for uranium removal with the perspectives of future works and challenges in this area.
... The iodide anions' retaining capability on the Ag-CAM was determined to be close to 31 mg I/g AgNPs. Given the high affinity between gold and the iodine atom, gold nanoparticles (AuNPs) have also been shown to be an efficient adsorbent for the removal of radioactive iodine from different aqueous systems (Zhang and Liu, 2020). ...
Freshwater has been incessantly polluted by various activities such as rapid industrialization, fast growth of population and agricultural activities. Water pollution is considered as one the major threatens to human health and aquatic bodies which causes various severe harmful diseases including gastrointestinal disorders, asthma, cancer, etc. The polluted wastewater could be treated by different conventional and advanced methodologies. Amongst them, adsorption is the most utilized low cost, efficient technique to treat and remove the harmful pollutants from the wastewater. The efficiency of adsorption mainly depends on the surface properties such as functional group availability and surface area of the adsorbents used. Since various waste-based carbon derivatives are utilized as adsorbents for harmful pollutants removal; nanomaterials are employed as effective adsorbents in recent times due to its excellent surface properties. This review presents an overview of the different types of nanomaterials such as nano-particles, nanotubes, nano-sheets, nano-rods, nano-spheres, quantum dots, etc. which have been synthesized by different chemical and green synthesis methodologies using plants, microorganisms, biomolecules and carbon derivatives, metals and metal oxides and polymers. By concentrating on potential research difficulties, this study offers a new viewpoint on fundamental field of nanotechnology for wastewater treatment applications. This review paper critically reviewed the synthesis of nanomaterials more importantly green synthesis and their applications in wastewater treatment to remove the harmful pollutants such as heavy metals, dyes, pesticides, polycyclic aromatic hydrocarbons, etc.
... The Nanoremediation pathway involves the utilization of reactive nanomaterials including metal oxides, bimetallic nanoparticles, carbon nanotubes, and nanocomposites for the decontamination and mineralisation of contaminants [17]. Few works have been reported on the utilization of nanomaterials as adsorbents for the remediation of various contaminants existing in water such as heavy metals, organic compounds, chlorinated compounds, pesticides, and inorganic ions [18][19][20][21]. Among the nanoparticles adsorbents employed for pollution remediation, semiconductor zinc nanoparticles have gained increasing attention owing to its innocuous, stability, large surface area, porosity, mechanical and thermal stability [21][22][23]. ...
Zinc semiconductor nanoparticles have been employed as potential adsorbents for the remediation of organic pollutants. However, the influence of its non-metallic components on the adsorption performance of zinc semiconductor nanoparticles is yet to be understood. Herein, using zinc oxide (ZnO) and zinc chalcogenide (ZnS) as adsorbents, we demonstrated the effect of O and S constituents on the adsorption performance of zinc semiconductor nanoparticles. The morphology, crystallinity, surface area, thermal stability, and the functionals group of both samples were investigated using scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), Fourier Transform Resonance Spectroscopy (FT-IR), respectively. Although the surface area of ZnS was observed to be 26 times that of ZnO, the Langmuir adsorption capacity for (TC) of the latter (78.70 mg/g) was significantly higher than the former (47.79 mg/g). The enhanced adsorption performance by ZnO is ascribed to its high porosity and broader point of zero charges (PZC). The present study establishes the impact of S and O on the adsorption performance of zinc nanoparticle adsorbents.
... Nano-remediation provides one of the best techniques to decontaminate the ground water. It is used against various contaminants such as heavy metals, organic compounds or hydrocarbons, chlorinated compounds, inorganic ions, and pesticides (Teow and Mohammad, 2019;Zhang and Liu, 2020). The application of nano-remediation in freshwater and wastewater is dependent on the usage of nano-adsorbents, which is a membrane process that relies on nano-catalysts or nanocomposites. ...
The absence of novel and efficient methods for the elimination of persistent organic pollutants (POPs) from the environment is a serious concern in the society. The pollutants release into the atmosphere by means of industrialization and urbanization is a massive global hazard. Although, the eco-toxicity associated with nanotechnology is still being debated, nano-remediation is a potentially developing tool for dealing with contamination of the environment, particularly POPs. Nano-remediation is a novel strategy to the safe and long-term removal of POPs. This detailed review article presents an important perspective on latest innovations and future views of nano-remediation methods used for environmental decontamination, like nano-photocatalysis and nanosensing. Different kinds of nanomaterials including nanoscale zero-valent iron (nZVI), carbon nanotubes (CNTs), magnetic and metallic nanoparticles, silica (SiO2) nanoparticles, graphene oxide, covalent organic frameworks (COFs), and metal organic frameworks (MOFs) have been summarized for the mitigation of POPs. Furthermore, the long-term viability of nano-remediation strategies for dealing with legacy contamination was considered, with a particular emphasis on environmental and health implications. The assessment goes on to discuss the environmental consequences of nanotechnology and offers consensual recommendations on how to employ nanotechnology for a greater present and a more prosperous future.
... Further, nanoparticles can increase the tolerance of plants against environmental stress conditions. Zhang and Liu (2020) reported nano particles have been known to cause nanotoxicity, which exerts unintended effects on the environment and human health when applied in soil and wastewater treatment. On the other hand some toxicity studies regarding nanomaterials also shown less adverse health effects if uses judiciously, but long-term investigation should be conducted to assess the full impact of these particles, in their initial and modified forms. ...
The radioactive contamination has been reported frequently from agricultural lands and ground water. The main reason behind the radioactive pollution is unprotected mining of radioactive elements, unsafe discard of nuclear industrial waste, military applications, dumping of medically used radioisotopes, globally situated (>400) nuclear power plants and use of phosphate fertilizers in farming. Radionuclides are well known potent carcinogens that may cause the various types of cancers to human and animals due to the long exposure to radioactive contaminated sites. To get rid of from the radioactive pollution there is a need of practically successful and cost effective bioremediation technologies that should able to decontaminate the effected lands and water to benefit the mankind. Microbial and phytoremediation are well studied methods for decreasing or gradually eliminating the radioactive contaminants. In this review, we discussed the different strategies of microbial and phytoremediation of radionuclides and recent advancements, that can play the major role in bioremediation of soil and water.
Due to its low capital cost, small equipment size, low energy consumption, and high efficiency, especially for pollutants in lower concentrations, membrane technology has gained a lot of attention for wastewater treatment. In this chapter, the development of 2D nanomaterial-modified membranes for wastewater treatment, desalination, and the removal of radioactive contaminants is presented. Surface roughness, hydrophobicity, porosity, and fouling resistance are just a few of the membrane properties that can be altered by incorporating 2D nanomaterials into the polymeric matrix. The significance of functionalization procedures in generating 2D nanocomposite hybrid membranes and their influence on the removal of various pollutants is also discussed. A combination of its large specific surface area, variable pore size, abundant surface active sites, and beneficial hydrophilic characteristics makes it a promising adsorbent for removing heavy metals and radionuclides from water. The effect of 2D nanomaterials embedded in a membrane toward removing various contaminants such as metal ions, organic compounds, colors, and bacteria is discussed methodically. The potential of 2D nanomaterial-functionalized membranes for wastewater regeneration is demonstrated with the help of some recent successes in this field.
Sr, as a typical artificial radionuclide, poses a serious threat to human health and the ecological environment. The selective removal of this radionuclide from industrial nuclear waste is crucial for our environment. Here we report a novel potassium fluoroaluminate, K2[(AlF5)H2O], which was synthesized by a simple low‐temperature one‐step method. It adopts a 1D AlF6‐chain structure, which consists of exchangeable potassium ions in between the infinite chains of octahedral Al centers. As a remarkable inorganic ionic exchanger, K2[(AlF5)H2O] has a high chemical stability (resistance of pH=~3‐12) and thermal stability (≥~300 °C). It possesses an excellent adsorption selectivity (Kd=~6.1×10⁴ mL ⋅ g⁻¹) and a maximum adsorption capacity of qm=~120.32 mg ⋅ g⁻¹ for Sr²⁺. Importantly, it still keep a very good selectivity for Sr²⁺ ions even in the presence of competing Na⁺, Mg²⁺ and Ca²⁺ aqueous solutions. K2[(AlF5)H2O] is the first example of fluoroaluminate ionic exchange materials that can capture Sr²⁺. This result opens up a new way to design and synthesize inorganic ionic exchangers for the selective removal of Sr²⁺ ions from radioactive waste water.
Radioactivity is a silent killer; even though radiations are not visible, they are strong enough to alter a cell’s normal functioning. The extent of damage by the radiation depends on the kind of radiation and its capability of penetration. X-rays and Gamma rays have the maximum penetration, and they cause the generation of free radicals within the cells. The free radicals are responsible for causing damage to some of the essential cellular components like proteins, nucleic acid, cell membranes, etc. Even nuclear wastewater is a rich source of radioactive waste and requires special prior treatment before being released into normal water bodies. Hence radioactive wastes impart a serious threat to the environment and the health of living organisms. Nanotechnology is a branch of science showing promising solutions for various scientific challenges. There is a wide array of research in this sector wherein scientists are trying to exploit the properties of nanotechnology to address the issue of radioactive waste removal. Nanotechnology can be used in the form of magnetic nanoparticles conjugated with specific chelator molecules to sequester molecules, or they can be used in the form of carbon-based nanomaterial for the adsorption of radioactive atoms. Recently, a research showed that graphene quantum dots (GQDs) can be used as smart nano-adsorbents of uranium (238U). Incorporation of ferrihydrite nanoparticles into cementitious materials can help in the immobilization of radioactive uranium and prevent its leaching by almost 50–57%. Hence, the applications of nanomaterials as magnetic nanoparticles, nano-adsorbents, etc. can be a hopeful solution to combat radioactive waste-mediated hazards in near future.KeywordsRadioactive decayNanocompositeRadionuclideMagnetic nanoparticlesCarbon NanotubesBiochar
Waste management represents a challenge due to the rapid increase in waste production and the emergence of new waste types. Overcoming the issue involves using innovative technologies such as nanotechnology. Nanotechnology uses nanomaterials, which are materials that have at least one dimension less than 100 nm. Due to their small size, these materials increase reactivity in processes such as adsorption and oxidation/reduction. The application of nanotechnologies is significant in the production of new materials to replace current raw materials, and in providing novel solutions for waste recycling and disposal. Furthermore, nanofiltration is effective in the treatment of metals, toxic waste, and nonbiodegradable materials of leachate. Nanomaterials, however, represent a safety risk for the environment, and a serious threat to human health due to their small size and long suspension time. This chapter deals with the use of nanotechnology in waste management, including reduction, recycling, treatment, and disposal phases.
Uranyl ions U(VI), are the common by-product of nuclear power plants and anthropogenic activities like mining, excess utilization of fertilizers, oil industries, etc. Its intake into the body causes serious health concerns such as liver toxicity, brain damage, DNA damage and reproductive issues. Therefore, there is urgent need to develop the detection and remediation strategies. Nanomaterials (NMs), due to their unique physiochemical properties including very high specific area, tiny sizes, quantum effects, high chemical reactivity and selectivity have become emerging materials for the detection and remediation of these radioactive wastes. Therefore, the current study aims to provide a holistic view and investigation of these new emerging NMs that are effective for the detection and removal of Uranium including metal nanoparticles, carbon-based NMs, nanosized metal oxides, metal sulfides, metal-organic frameworks, cellulose NMs, metal carbides/nitrides, and carbon dots (CDs). Along with this, the production status, and its contamination data in food, water, and soil samples all across the world are also complied in this work.
Complex hierarchical metamaterials are currently the focus of many cutting‐edge studies due to their potential to advance such critically important areas of technology as energy storage and transformation, sensing, photovoltaics, nano‐medicine, antibacterial and self‐regenerating materials. However, the deterministic design of novel hierarchical metamaterials remains problematic due to the lack of efficient, highly reliable methods for controlling the internal structure and architecture of materials. A comprehensive advanced model is proposed to simulate the formation of complex hierarchical metamaterials with a controllable structure. The control is achieved via selective deposition of noble metal nanoparticles (Au, Au, Pd, Pt). Moreover, the novel method for the nanofabrication is theoretically examined and experimentally verified. This approach allows for the sophisticated spatiotemporal control of growth conditions and, as a result, achieving the targeted internal structure of metamaterials. This opens a way to the deterministic design and formation of complex multi‐material metamaterials on the basis of metal oxides and noble metal nanoparticles. Moreover, a fundamental insight related to the longstanding question about the prevalence of bottom‐up versus top‐down growth for various materials and systemswhich is challenging to directly verify experimentally is presented.
The capture of the radionuclides strontium and cesium is of great importance to the environment, human health, and the sustainable development of nuclear energy, and zirconium phosphate with excellent ion exchange capacity has potential application in this field. In this work, we organically granulated zirconium phosphate to induce the formation of composite bead materials (CA@ZrP) with a calcium-containing phase with selectivity for Sr2+ and Cs+ higher than that of pure ZrP in low-pH environments and competing ionic environments. The adsorption performance of the material was systematically investigated. It was concluded that the adsorption performance of CA@ZrP improved with an increase in temperature, and under the dynamic adsorption experimental conditions, the treatment capacity of CA@ZrP for Sr2+ and Cs+ reached 404.79 and 302.2 bed volumes, respectively. The systematic study and characterization showed that the generation of the calcium-containing phase [Ca0.55ZrH0.9(PO4)2] promoted the exchange of Ca2+ with Sr2+ and Cs+, thus improving the selectivity of the composite beads. The highly selective composite bead material can be prepared in batches and easily recycled, providing a new idea for practical engineering applications.
Mesoporous titanosilicates (TiSil) with a size of almost 25 nm were prepared by an alkali-assisted hydro-thermal route, as an choice for developing efficient adsorbents of Th(IV) ions. TiSil were functionalized with the amino functional group (-NH 2 ) from 3-aminopropyltriethoxysilane (APTES) by post-preparation method. The obtained amino-grafted titanosilicates (TiSilNH 2 ) were characterized by Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), X-ray Diffraction (XRD) and Fourier-Transform Infrared Spectroscopy (FTIR) techniques. Adsorption of Th(IV) ions on TiSilNH 2 was examined in aqueous solution. Response surface methodology (RSM) based on central composite design (CCD) was applied to optimize the four essential process variables namely initial pH and initial concentration of Th(IV) ions of aqueous solution, amount of adsorbent, and adsorption process temperature for the Th(IV) removal. The adequacy of the model was investigated, and it was deemed to be statistically significant. The optimal predicted adsorption capacity of TiSilNH 2 for Th(IV) ions was 83.04 mg/g and the actual value was 84.8 mg/g. The equilibrium adsorption data were fitted to Langmuir, Freundlich, Dubinin–Radushkevich and Temkin isotherm models. The equi-librium data were best re-presented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 87.71 mg/g. The thermodynamic parameters indicated that the Th(IV) adsorption on the TiSilNH 2 was a spontaneous, and endo-thermic process at the studied temperatures and occurred via physisorption. Adsorbent recovery by using 0.5 M HNO 3 solution for adsorbent reuse indicated that the adsorbent was regenerable and could be employed frequently.
Global concerns related to the rise in worldwide energy demand, along with the pledge to minimize greenhouse gas emissions, have encouraged developed nations to opt for clean, efficient, and sustainable nuclear energy. However, the generation of volatile radioactive by-products (such as ¹²⁹I and ¹³¹I) during the operation of a nuclear power plant is considered a serious environmental concern, especially in the case of an accident. As a result, the development of efficient iodine sequestering adsorbents from both aqueous and vapor media is an important contemporary research domain. In this regard, we report herein a guanidinium-based ionic covalent organic network (iCON), denoted as iCON-4, that was prepared using a Schiff-base polycondensation reaction between terephthalaldehyde and triaminoguanidinium chloride. The polymeric iCON-4 is robust and it exhibits good physiochemical stability. The positively charged guanidinium moieties present in iCON-4 facilitate the ion-exchange based adsorption of iodine leading to faster uptake kinetics as well as relatively higher capture capacity. In fact, the iCON-4 polymeric network shows iodine removal greater than 99% from the aqueous medium within two minutes and it shows excellent affinity (distribution coefficient, ∼10⁵ ml g⁻¹) towards iodine in the aqueous medium. Also, it displays fast kinetics during the removal of iodine species from aqueous water samples collected from diverse water bodies such as seas, rivers and lakes. Additionally, iCON-4 registered remarkable selectivity while capturing iodide ions in the presence of other competing anionic species. For practical applications, iCON-4 can be reused up to seven times without any remarkable loss in uptake performance. Thus, iCON-4 has been developed as a strategic material with all desirable attributes required in an adsorbent for practical applications.
Low-dimensional copper oxide nanostructures are very promising building blocks for various functional materials targeting high-demanded applications, including energy harvesting and transformation systems, sensing and catalysis. Featuring a very high surface-to-volume ratio and high chemical reactivity, these materials have attracted wide interest from researchers. Currently, extensive research on the fabrication and applications of copper oxide nanostructures ensures the fast progression of this technology. In this article we briefly outline some of the most recent, mostly within the past two years, innovations in well-established fabrication technologies, including oxygen plasma-based methods, self-assembly and electric-field assisted growth, electrospinning and thermal oxidation approaches. Recent progress in several key types of leading-edge applications of CuO nanostructures, mostly for energy, sensing and catalysis, is also reviewed. Besides, we briefly outline and stress novel insights into the effect of various process parameters on the growth of low-dimensional copper oxide nanostructures, such as the heating rate, oxygen flow, and roughness of the substrates. These insights play a key role in establishing links between the structure, properties and performance of the nanomaterials, as well as finding the cost-and-benefit balance for techniques that are capable of fabricating low-dimensional CuO with the desired properties and facilitating their integration into more intricate material architectures and devices without the loss of original properties and function.
As famed quantum physicist W. Pauli once said, “The surface was invented by the devil”. The nonequilibrium state of particles forming the surface, and the presence of dangling bonds transform the surfaces into a 2D reactor with high physical and chemical reactivity. When two such active surfaces are matched, their interface becomes even more reactive, giving rise to novel properties or enhanced performance. For this reason, much effort is applied to design nanoengineered interfacial systems for applications spanning all facets of human life. This review article discusses recent, mostly within two years, progress in the design of complex, sophisticated carbon-based interfacial material systems for energy and photonics applications, with the aim to emphasize some of the most interesting and important examples of such systems. Differences in the processes that take place on flat and 3D (curved) surfaces are discussed, with the view of guiding the design and construction of complex functional interfaces, focusing on several points that are of particular importance to the ongoing development of advanced interfacial material systems. © 2022 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH.
Clean water is vital in the creation of energy and sustenance of life. However, the pollution of water and the absence of potable water are global problems resulting from agricultural and industrial activities. We have witnessed significant growth in the pollution of water by organic compounds like PAH. Experts have made an effort to establish favorable techniques for the treatment of PAH polluted water. These techniques are either thermal, biological, physical or chemical. Bioremediation, chemical oxidation, solid-phase extraction, coagulation, photocatalytic degradation and adsorption using graphenes, mesoporous silica and agricultural wastes are techniques that are already in use in the field treatment of PAHs while electrokinetic remediation and nanoremediation are still in their developmental stage. Several reviews on the treatment of sediments and soils contaminated with PAHs have been published, but only a few reviews center mainly on the removal of PAHs in water. Therefore, this review aims to provide information on the techniques used in the treatment of water contaminated with PAHs. Techniques that are already in use and those that are in their developmental stage were reviewed. The successes of these methods, limitations, constraints and field procedures were analyzed and this will help to inform decision making.
Water is vital to sustain life on Earth. However, the planet's freshwater resources are constantly being depleted due to a variety of factors, including population growth and increased water use as the growing industrial and agricultural sectors consume large amounts of water. There is also the factor of the increase in the welfare of individuals, which is usually accompanied by an increase in water consumption. Therefore, there is a strong need to conserve water resources, as well as the need to treat wastewater for a variety of uses. Organic contaminants, heavy metals, radioactive isotopes, and pathogens can all be found in wastewater as pollutants. Wastewater treatment methods aim to eliminate these pollutants from the water. Nanotechnology is one of the state-of-the-art technologies that can be used to treat wastewater. In this chapter, we have highlighted the most important nanomaterials that are used in wastewater treatment. Emphasis has been given to the most important mechanisms involved in the treatment process. The role of nanomaterials in nanosensing of water pollutants was illuminated. We also shed some light on the most important pollutants in wastewater and how different nanotechnology techniques have been applied to purify water from these pollutants. Finally, the limitations that prevented the application of nanomaterials in the field of wastewater purification on the large scale were discussed.
This review is devoted to the problem of extracting americium from aqueous media of various origins by the sorption method based on the materials of modern world scientific studies published during two last decades. The methods for quantitative assessments of the effectiveness of sorbents are considered. The selection of data for Am(III) was substantiated taking into account the fact that trivalent lanthanides, especially Eu, are oten taken as a chemical analogue of trivalent actinides Am and Cm. Various types of sorbents and materials used for binding americium radionuclides, methods of their preparation and sorption mechanisms are considered in detail. In addition, this review comprehensively considers sorption processes involving americium occurring in radioactive storages.
The effective and efficient capture as well as storage of radioisotopes of iodine is of significant importance in the treatment of nuclear waste. Further, the use of radioisotopes of iodine in medical therapy requires proper capture of radioactive iodine. Thus, there is a pressing need to develop novel adsorbents obtained using easy and simple methods that can capture iodine from various media with good uptake capacity. With this target, a new triptycene-based porous organic network (TP_POP-7) was designed and synthesized using a flexible trialdehyde with a triazine core and a rigid three-dimensional triptycene triamine as monomers. The two trifunctional monomers were covalently linked using the Schiff base reaction. TP_POP-7 is a porous organic polymer with good thermal and chemical stability. Due to the presence of abundant electron rich arene rings and N centers in the polymeric framework, efficient interaction with iodine was anticipated. Indeed, TP_POP-7 proved to be a promising material for capturing iodine from various media/conditions such as iodine vapor at elevated temperature (75 °C: 4215 mg g⁻¹) and room temperature (25 °C: 2040 mg g⁻¹), iodide ions from aqueous solution (2312 mg g⁻¹) and molecular iodine from organic solution (865 mg g⁻¹). Further, TP_POP-7 is a recyclable adsorbent without much compromise in its capture performance. Considering the high iodine uptake values under different conditions with good retention capability, TP_POP-7 emerges as one of the best materials for reliable capture and storage of iodine.
In this study, ferromanganese cobalt potassium cyanide/silica composite (SiO2-KMCHCF) was prepared by a modified coprecipitation method, and the static adsorption of Cs+ and Sb(V) were carried out. The results showed that the material had a regular structure, was not easy to agglomerate, and more compatible functional groups (HCTMA+) and groups (Si–OH), had strong adsorption capacity for Cs+ and Sb(V). At pH = 7 and initial concentration of 10 mg/L, the maximum removal rates of Cs+ and Sb (V) were 92% and 80%, respectively. The pseudo-second-order kinetic and Langmuir model had the best fitting correlation, and the maximum adsorption capacity was 200.4 mg/g and 21.85 mg/g, respectively.
Recent advancements in nanotechnology towards wastewater treatment especially in industries has drawn huge attention. Numerous studies have shown that nanomaterials can effectively remove various pollutants in water and thus have been successfully applied in water and wastewater treatment. This chapter will mainly focus on the application of various nanoparticles including some new smart materials which are based on molecular imprinting technology for wastewater treatment and the potential application in industry. Drawbacks associated with the nanotechnology are also discussed and the major problems associated with industrialization are also summarized.
Low‐ and negative‐value (waste) products represent a valuable resource. Its use as a source for the fabrication of high value materials represents a lucrative pathway to increasing sustainability and decreasing the economic cost of various industries. Thermochemical methods for the valorization of biowaste and low‐value natural products are simple and cheap yet sufficiently efficient to deliver significant economic benefits. Plasma‐based methods represent another family of technologies for waste‐to‐value conversion. The nanostructure nucleation and growth in plasmas involve a complex set of physical and chemical processes that occur in bulk plasma and on surfaces. The choice between these two types of technology assumes a complex optimization that takes into account several factors including the cost of precursors; initial outlay and operating cost of equipment; the cost of labor; the cost of production engineering including the research and development efforts for designing the industrial technology, which is typically higher for the plasma‐based systems, and so on. In this article a technology level comparison of thermochemical and plasma‐based techniques for the valorization of raw and waste biomass, where the intent is to use the resulting products for environmental remediation, energy storage, optoelectronics, and biomedical applications, is presented.
In this study, nanocomposite of Bismuth/2‐(Dimethylamino)ethyl methacrylate/Starch (Bi/DMAEMA/Starch) synthesized using ionizing radiation. The prepared nanocomposite characterized and compared with the parent (DMAEMA/St) hydrogel using Fourier transform infrared spectroscopy [FTIR], X‐ray diffraction [XRD] and Thermogravimetric analysis [TGA]. The presence of nanoparticles confirmed by Transmission Electron Microscopy [TEM]. The prepared nanocomposite used to remove Cobalt ions from their wastes as a simulation of radioactive waste management. The optimization of effective parameters such as initial values, contact time, concentration and temperature on the adsorption process studied. The results proved that the Langmuir isothermal model describes well the absorption process. The pseudo‐second‐order kinetic model suitable for describing the adsorption kinetics. Thermodynamic parameters evaluated for the adsorbent systems. The prepared nanocomposite showed potential behavior for the removal of Co2+ ions. This article is protected by copyright. All rights reserved
The treatment of nuclear wastewater is one of the most urgent and arduous tasks currently, but traditional adsorption materials are significantly limited in practice due to their high demands on auxiliary operations (e.g., shaking or centrifugation) caused by poor stability or recyclability. To tackle this challenge, a water-based ferrofluid composed of magnetic nanoparticles grown in polyethylenimine branches is reported and applied to nuclear wastewater treatment. It is demonstrated that the ferrofluid can keep stable spontaneously in a wide pH range (3–11) out of their ultra-small size, strong electropositivity as well as high charge buffering capacity to achieve shaker-free adsorption, and can be magnetically separated after the neutralization of their positive charge to achieve convenient recycle. Meanwhile, it is found that the ferrofluid shows wide pH/adsorbate applicability and strong ion selectivity in radionuclides absorption. Furthermore, it is anticipated to achieve maximum adsorption capacities for U(VI), Sr(II) and Co(II) as high as 331.5, 427.8 and 759.6 mg/g, respectively. With these characteristics, this ferrofluid outperforms other reported adsorbents. In conclusion, this work provides a practical and effective radioactive wastewater treatment strategy, and enlightens the development of materials for other applications facing the dilemma of incompatible stability and recyclability.
The continuous development and modernization of various projects have a significant human and environmental impact. The important environmental impact appears in contaminating of clean water because of the industrial wastes such as the organic one (e.g. chemicals, dyes, and pesticide), inorganic (e.g. heavy metal ions) and radioactive waste (e.g. Uranium (U(VI)), 65Zn(II) and 60Co(II)). This chapter will focus on radioactive and nuclear waste removal because it has a great effect on the environment. Radioactive waste is coming from the generation of nuclear power and producing of different radioactive materials in various commercial sectors. Nanocomposites based polymers have many advantages that enable exhibit the suggested solutions in environmental applications. Polymer nanocomposites have a high ability and selectivity to uptake different pollutants. Conducting polymers enhanced the efficiency of radioactive waste removal. Moreover, the incorporation of magnetic nanoparticles inside polymer nanocomposites shows an improvement in radioactive removal efficiency.KeywordsNanocompositesRemovalWasteRadioactiveMagneticConducting polymer
Capture of trace amounts (parts per trillion or ppt level) of 90 Sr from highly Na +-rich (5 M or 115 000 parts per million) liquid wastes produced from reprocessing of spent nuclear fuel rods is crucial for continuous operation of nuclear power plants. However, no sorbents have shown such abilities. We now report that a novel layered vanadosilicate, SGU-7, with the unit cell parameters of a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, b = 100.28, and space group of P12 1 /a1, can effectively capture 90 Sr from a 5 M Na + solution containing 6.2 ppt of 90 Sr. It also effectively captures 1-ppb level 226 Ra from 2 M NaCl solution, and Cs + and Sr 2+ from groundwater, demonstrating that it can be immediately used to remedy groundwater and soil contaminated with 226 Ra, 90 Sr, and 137 Cs. The contribution of nuclear power plants to the world's electricity is currently significant (11%) 1 and it will continue increasing in the future. 2 However, nuclear power plants produce spent nuclear fuel rods which not only contain unused fuel and useful but also harmful fission products. Therefore, they are reprocessed to recover unused fuel and separate useful and harmful fission products. 3 Among the harmful fission products, 90 Sr is the most biohazardous species because its fission yield is high (5.73% with U-235 as the fuel), its half-life is medium (28.8 years), 4,5 and it readily accumulates in human and animal bones causing blood and bone cancers afterwards by emission of high energy b rays. 6 Accordingly, the US Environmental Protection Agency (EPA) set the upper limit of 90 Sr-induced radioactivity in drinking water to be 8 pCi L À1 or 0.3 Bq L À1 , which corresponds to B0.057 ppq (parts per quadrillion) or 6.3 Â 10 À16 M of 90 Sr in terms of chemical concentration. This means that essentially all 90 Sr must be removed from the reprocessing liquid wastes before they are released to the environment. In relation to this, the concentrations of 90 Sr in reprocessing liquid wastes range between B7 ppt (parts per trillion) 7 and 26 ppb (parts per billion). 8,9 In fact, the concentration of 90 Sr in the low edge (B7 ppt) itself is already a very low concentration to be removed from a solution even when it exists as a single component in the solution. On the other hand, the reprocessing liquid wastes usually contain Na + , with the concentrations often exceeding 115 000 ppm (parts per million) or 5 M. 8 Therefore, efforts should be directed towards developing 90 Sr removers which can extract B7 ppt of 90 Sr from reprocessing waste solutions which contain Na + with concentrations higher than that of 90 Sr by at least 63 billion times. The 90 Sr remover should also be radiation
The selective removal of strontium ion (Sr²⁺) from seawater has aroused great attention since the occurrence of the Fukushima nuclear accident. Inorganic ion adsorbents show promise in the treatment of large amounts of polluted water. Among of them, the titanates present a stability and selectivity towards strontium, but limited by poor mechanical and granulometric properties. In this work, a novel silica-based titanate (Na2TinO2n+1/SiO2) was synthesized by sol-gel method and then characterized by X-ray diffraction (XRD), thermal analysis (TG-DSC), XPS and BET. Characterization suggested that the crystal of the titanate was greatly affected by temperature, leading to the difference of the adsorption properties. The silica-based material showed a significant increase in specific surface area; and the adsorption process was found to be an ion-exchange reaction occurred inside these particles. Finally, the material calcined at 500 °C was selected to conduct the following batch experiments. Results suggested that the adsorption data of Sr²⁺ fitted the Langmuir adsorption model well; the pH from 3 to 10 contributed to a better Sr²⁺ adsorption behavior, with adsorption amount approaching 33.31 mg/g; the adsorption could reach equilibrium within 5 min with data fitted by the pseudo second kinetic model. And the selectivity coefficient revealed that this material had higher selectivity towards Sr²⁺ contrast to other alkali and alkaline-earth metals. Based on above static experimental results, the dynamic treatment was designed and carried out in a glass column. This test demonstrated that Na2TinO2n+1/SiO2 could remove the strontium from the simulated seawater effectively and efficiently with no leakage. Generally, this work provides an excellent material to removing Sr²⁺ from high salinity solution with good column compatibility.
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A novel silica-based titanate (Na2xTinO2n+x/SiO2) were synthesized by sol-gel method that exhibited excellent Sr²⁺ ion-exchange properties in large amounts from simulated radioactive seawater. The dynamic treatment was designed and carried out in a glass column. The breakthrough capacity for treatment of simulated solutions reached 950 bed volumes. Generally, this work provides an excellent material to removing Sr²⁺ from high salinity solution with good column compatibility.
A novel nanocomposite based on the combination of nanobentonite with nanopolyaniline and nanomanganese oxide (N-Bent–NPANI–NMn3O4) was synthesized and investigated to extract Co/Zn ions from water using batch technique and ⁶⁰Co/⁶⁵Zn radionuclides from radioactive wastewater using column techniques. Characterization was established by High resolution-transmission electron microscopy (HR-TEM), Scanning electron microscope, X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier transform infrared spectrophotometer. The image of HR-TEM indicated that the produced nanocomposite was ranged from 59.07 to 83.38 nm. Solution pH, time of reaction, amount of solid and metal concentration, all of these parameters were inspected and optimized as fundamental factors during the extraction process. The obtained results implied that the ideal conditions for extraction were pH 6 and 7, reaction time 10 and 20 min, for Co and Zn ions, respectively. The highest removal capacities were found 255.28 and 202.22 mg g⁻¹ for Co and Zn, respectively by using 5 mg nanocomposite. Excellent recoveries were obtained as 94.0–94.5% and 92.0–93.0% for removal of Co–⁶⁰Co and of Zn–⁶⁵Zn ions, respectively from the examined samples.
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Scarcity of fresh drinkable water has escalated to be the one of the major global problem. Traditional wastewater treatment technologies are not adequate enough to produce safe water due to increasing demand of water coupled with stringent health guidelines and emerging contaminants. On that note, the advent of nanotechnology has given immense scope and opportunities for the removal of heavy metals, microorganisms and organic pollutants from wastewater and has emerged to be a very dynamic branch in the utilization of nanotechnology due to their unique physiochemical and biological properties compared to their bulk. Exploiting these properties of high specific surface area and surface reactivity have resulted in the excessive use and study of nanoparticles in wastewater remediation. The use of various nanomaterials, including carbon based nanomaterial, metal and metal oxides nanoparticles as were focused on, and their mode of action towards waste water remediation were discussed. Herein we tried to incorporate an overview of recent advances in nanotechnologies for water and wastewater treatment and understand various advantages, limitations and future direction.
Increasing concerns regarding the adverse effects of radioactive iodine waste have inspired the development of a highly efficient and sustainable desalination process for the treatment of radioactive iodine-contaminated water. Because of the high affinity of silver towards iodine species, silver nanoparticles immobilized on a cellulose acetate membrane (Ag-CAM) and biogenic silver nanoparticles containing the radiation-resistant bacterium Deinococcus radiodurans (Ag-DR) were developed and investigated for desalination performance in removing radioactive iodines from water. A simple filtration of radioactive iodine using Ag-CAM under continuous inflow conditions (approximately 1.5 mL/s) provided an excellent removal efficiency (>99%) as well as iodide anion-selectivity. In the bioremediation study, the radioactive iodine was rapidly captured by Ag-DR in the presence of high concentration of competing anions in a short time. The results from both procedures can be visualized by using single-photon emission computed tomography (SPECT) scanning. This work presents a promising desalination method for the removal of radioactive iodine and a practical application model for remediating radioelement-contaminated waters.
The number of studies on the capture of radioactive iodine compounds by porous sorbents has regained major importance in the last few years. In fact, nuclear energy is facing major issues related to operational safety and the treatment and safe disposal of generated radioactive waste. In particular during nuclear accidents, such as that in 2011 at Fukushima, gaseous radionuclides have been released in the off-gas stream. Among these, radionuclides that are highly volatile and harmful to health such as long-lived ¹²⁹I, short-lived ¹³¹I and organic compounds such as methyl iodide (CH3I) have been released. Immediate and effective means of capturing and storing these radionuclides are needed. In the present review, we focus on porous sorbents for the capture and storage of radioactive iodine compounds. Concerns with, and limitations of, the existing sorbents with respect to operating conditions and their capacities for iodine capture are discussed and compared.
Prussian blue (PB) is known to be an effective material for radioactive cesium adsorption, but its nano-range size make it difficult to be applied for contaminated water remediation. In this study, a simple and versatile approach to immobilize PB in the supporting matrix via surface functionalization was investigated. The commercially available poly vinyl alcohol (PVA) sponge was functionalized by acrylic acid (AA) to change its major functional group from hydroxyl to carboxylic, which provides a stronger ionic bond with PB. The amount of AA added was optimized by evaluating the weight change rate and iron(III) ion adsorption test. The FTIR results revealed the surface functional group changing to a carboxyl group. The surface functionalization enhanced the attachment of PB, which minimized the leaching out of PB. The Cs ⁺ adsorption capacity significantly increased due to surface functionalization from 1.762 to 5.675 mg/g. These findings showed the excellent potential of the PB-PAA-PVA sponge as a cesium adsorbent as well as a versatile approach for various supporting materials containing the hydroxyl functional group.
Photocatalysis has received ever‐growing attention as a promising alternative to traditional water treatment technologies for waterborne biohazard inactivation. Due to unique optical, electronic, physicochemical properties and feasibility of functional architecture assembly, two‐dimensional (2D) nanomaterials have become important in developing novel photocatalysts. This review summarizes the recent progress in configuring nanostructures with 2D materials as building blocks for photocatalytic water disinfection. In this review, five categories of 2D nanomaterials, that is, graphene, graphitic carbon nitride, 2D metal oxides and metallates, metal oxyhalides and transition metal dichalcogenides, for photocatalytic pathogen inactivation are introduced. First, the synthesis process, nanostructure engineering and disinfection performance of 2D‐based photocatalysts are reviewed in categories. In the following section, the bacteria destruction mechanism based on the generation and roles of reactive species (RSs) is presented. Moreover, the effects of the chemical characteristics of the water matrix on photocatalytic bactericidal performance are discussed. Finally, the challenges regarding the development and application of 2D‐based photocatalysts for highly efficient water sterilization are highlighted. © 2018 Society of Chemical Industry
In this work, we elucidate polymer-layered hollow Prussian blue-coated magnetic nanocomposites as an adsorbent to remove radioactive cesium from environmentally contaminated water. To do this, Fe3O4 nanoparticles prepared using a coprecipitation method were thickly covered with a layer of cationic polymer to attach hollow Prussian blue through a self-assembly process. The as-synthesized adsorbent was confirmed through various analytical techniques. The adsorbent showed a high surface area (166.16 m2/g) with an excellent cesium adsorbent capacity and removal efficiency of 32.8 mg/g and 99.69%, respectively. Moreover, the superparamagnetism allows effective recovery of the adsorbent using an external magnetic field after the adsorption process. Therefore, the magnetic adsorbent with a high adsorption efficiency and convenient recovery is expected to be effectively used for rapid remediation of radioactive contamination.
A comparative study between two nanosorbents, nanopolyaniline (NPANI) and nanopolyaniline coated with nanosilver oxide (NPANI-NAg2O) is explored to dispose the divalent species of Zn/Co from water and radioactive isotopes ⁶⁵Zn/⁶⁰Co from radioactive wastewater using batch and column techniques. NPANI-NAg2O nanocomposite was synthesized via solid-solid reaction. Characterization was achieved using FT-IR, TGA, XRD, SEM, HR-TEM, and surface area analysis. The images of SEM and HR-TEM confirmed the success of the modification process and the particle size was found in the range 28.78–68.28 nm (NPANI) and 25.74–85.71 nm (NPANI-NAg2O), respectively. Solution pH, contact time, solid dosage, and ionic concentration of the metals were studied as fundamental factors. The obtained results indicated that the optimum conditions to dispose Zn/Co divalent species using NPANI were pH 7 and 30–33 min, while NPANI-NAg2O exhibited the optimum conditions at pH 7 and 20–30 min. The maximum removal capacities were 100.1 and 139.75 mg/g for Zn(II) and 57.93 and 112.1 mg/g for Co(II) using NPANI and NPANI-NAg2O, respectively.
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We report herein the fabrication of an environmentally friendly, low-cost and efficient nanostructured mesoporous monetite plate-like mineral (CaHPO4) as an adsorbent for removal of radioactive cesium ions from aqueous solutions. The phase and textural features of the synthesized mesoporous monetite were well characterized by XRD, FTIR, SEM, HRTEM, DLS, TGA/TDA, and N2 adsorption/desorption techniques. The results indicate that the cesium ions were effectively adsorbed by the mesoporous monetite ion-exchanger (MMT-IEX) above pH 9.0. Different kinetic and isotherm models were applied to characterize the cesium adsorption process. The fabricated monetite exhibited a monolayer adsorption capacity up to 60.33 mg g⁻¹ at pH of 9.5. The collected data revealed the higher ability of CaHPO4 for the removal of Cs(I) from aqueous media in an efficient way.
Correction for ‘Interfacial growth of a metal–organic framework (UiO-66) on functionalized graphene oxide (GO) as a suitable seawater adsorbent for extraction of uranium( vi )’ by Peipei Yang et al. , J. Mater. Chem. A , 2017, 5 , 17933–17942.
We present a comprehensive review of the applications of biosynthesized metallic nanoparticles (NPs). The biosynthesis of metallic NPs is the subject of a number of recent reviews, which focus on the various ''bottom-up'' biofabrication methods and characterization of the final products. Numerous applications exploit the advantages of biosynthesis over chemical or physical NP syntheses, including lower capital and operating expenses, reduced environmental impacts, and superior biocompatibility and stability of the NP products. The key applications reviewed here include biomedical applications, especially antimi-crobial applications, but also imaging applications, catalytic applications such as reduction of environmental contaminants, and electrochemical applications including sensing. The discussion of each application is augmented with a critical review of the potential for continued development.
The efficient elimination of radionuclides from aqueous solutions is crucial for environmental protection from radionuclides’ pollution. The construction of octahedral molecular sieve (OMS-2) nanoporous membranes is of great technical importance for different kinds of applications like purification filter, catalysts, oil separation, seawater desalination and pollutant elimination. The facile synthesis of freestanding materials demonstrated uniform and monodispersed nanostructures and a cross-sectional pattern of the membranes, which is easily recycled in the process of adsorption and separation of pollutants from aqueous solutions. The OMS-2 exhibited rapid adsorption kinetics and high adsorption capacities of U(VI) (348 mg/g) and Eu(III) (106 mg/g) at pH = 5.0 ± 0.1 and T = 298 K. The paper-like membranes still retained the original filiform morphologies and showed extraordinary stability after 6 adsorption cycles. The surface complexation and ion exchange were the main mechanisms for the uptake of radionuclides, and the change of water environment had little influence on radionuclide adsorption efficiency. Based on the high adsorption capacity and excellent recycle ability, the OMS-2 membranes are considered as superior adsorbents for the efficient elimination of metal ions in the decontamination of polluted water.
Metal sulfides are promising materials because their ability to capture radioactive nuclides from wastewater is superior to many others. Herein, Na/Zn/Sn/S (NaZTS) quaternary metal sulfide nanosheets were fabricated using a one-pot hydrothermal method. A series of characterizations revealed that these nanosheets had a structure identical to Na5Zn3.5Sn3.5S13•6H2O, consisting of [Zn3.5Sn3.5S13]5− frameworks and Na+ ions located at the center and corner of the open channels. Because of the S2− ligands in its structure, NaZTS is a soft Lewis base and showed high affinity toward Sr2+ ions. NaZTS was employed to remove Sr2+ from aqueous solutions and exhibited ultrafast kinetics (an equilibrium time of 5 min), a broad active pH range (a removal rate of > 98.4% at pH 3–12), and non-desorptive behavior (a Sr2+ desorption rate of < 0.04%). Its maximum adsorption capacity according to the Langmuir model was 40.4 mg g−1 at 318 K. The effects of adsorbent dosage and coexisting ions on Sr2+ adsorption were also discussed. Macroscopic adsorption experiments and microscopic X-ray photoelectron spectroscopy were used to study the adsorption mechanism, and the outstanding ability of NaZTS to capture Sr2+ ions could be attributed to ion exchange and strong Sr•••S bonding. This work highlights the excellent adsorption of Sr2+ by NaZTS, which makes it a promising material for removing radioactive Sr2+ in cleanups of radioactive pollution.
With the development of nuclear energy, large amounts of radionuclides are inevitably released into the natural environment. It is necessary to eliminate radionuclides from wastewater for the protection of environment. Nanomaterials have been considered as the potential candidates for the effective and selective removal of radionuclides from aqueous solutions under complicated conditions because of their high specific surface area, large amounts of binding sites, abundant functional groups, pore-size controllable and easily surface modification. This review mainly summarized the recent studies for the synthesis, fabrication and surface modification of novel nanomaterials and their applications in the efficient elimination and solidification of radionuclides, and discussed the interaction mechanisms from batch experiments, spectroscopy analysis and theoretical calculations. The sorption capacities with other materials, advantages and disadvantages of different nanomaterials are compared, and at last the perspective of the novel nanomaterials is summarized.
Graphene with atomic layer of sp2-hybridized carbon atoms in a hexagonal structure has attracted multidisciplinary attention since its discovery. Due to the inherent advantages of large specific surface area and abundant functional groups, its derivative graphene oxide (GO) nanomaterials have achieved large-scale development in effective pollution treatment. In the past few years, novel GO-based nanomaterials through coupling with other nanomaterials have been synthesized with significant process and applied for efficient elimination of different kinds of pollutants. This paper aims to summarize recent research results on the excellent removal ability of GO-based nanomaterials for various heavy metal ions in aqueous solutions. The synthesis, adsorption process characteristics and interaction mechanism of the adsorbent are emphasized and discussed. The effects of various environmental conditions are outlined. At last, a brief summary, perspective and outlook are presented. This review is intended to provide some thrilling information for the design and manufacture of GO-based nanomaterials for the elimination of heavy metal ions from wastewater in environmental pollution management.
The effect of Cr(VI) and bisphenol A (BPA) on U(VI) photoreduction by C3N4 photocatalyst was demonstrated by the batch experiments, electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques. The batch experiments manifested that Cr(VI) and BPA enhanced the photocatalytic activity of C3N4 for U(VI) photoreduction, whereas U(VI) photoreduction was significantly diminished with increased pH from 4.0 to 8.0. According to radical scavengers and ESR analysis, U(VI) was photo-reduced to U(IV) by photo-generated electrons of conduction band edge, whereas Cr(VI) was reduced to Cr(III) by H2O2. BPA and its products such as organic acid and alcohols can capture photoinduced holes, which resulted in the enhancement of U(VI) photoreduction to U(IV). XPS and XANES analyses demonstrated that U(VI) was gradually photoreduced to U(IV) by C3N4 within irradiation 60 min, whereas U(IV) was reoxidized to U(VI) with increasing irradiation time. EXAFS analysis determined that the dominant interaction mechanisms of U(VI) on C3N4 after irradiation for 240 min were reductive precipitation and inner-sphere surface complexation. This work highlights the synergistic removal of radionuclides, heavy metals and persistent organic pollutants by C3N4, which is crucial for the design and application of high-performance photocatalyst in actual environmental cleanup.
Nano zero-valent iron (nZVI) has received significant attention for its potential applications in the area of removing all kinds of toxic and radioactive metal ions. This chapter summarizes the preparation and use of pristine nZVI, modified nZVI, and supported nZVI. The physicochemical properties as well as the adsorption and reduction behaviors and mechanisms are also discussed in the cleanup of hazardous metal ion wastewater. Moreover, the advantages and limitations of the types of nZVI-based material and their functionality are evaluated. The scopes and limitations of these adsorbents will be addressed while investigating the various types of hazardous metal ions that are harmful.
Radioactive waste, such as ⁹⁰ Sr, ¹³⁴ Cs, and ¹³¹ I, from the Fukushima nuclear spill highlighted the need to find effective adsorbents for scrubbing radioactive ions from seawater. In this issue of Chem, Wang and colleagues report a remarkably ⁹⁰ Sr-selective metal-organic framework (SZ-4) that operates with a two-step ion-exchange mechanism and at a wide pH range while being active and intact when tested in actual seawater.
Capture of trace amounts (parts per trillion or ppt level) of 90Sr from highly Na+-rich (5 M or 115,000 parts per million) liquid wastes produced from reprocessing of spent nuclear fuel rods is crucial for continuous operation of nuclear power plants. However, no sorbents have shown such abilities. We now report that a novel layered vanadosilicate, SGU-7, with the unit cell parameters of a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2°, and space group of P121/a1, can effectively capture 90Sr from a 5 M Na+ solution containing 6.2 ppt of 90Sr. It also effectively captures 1-ppb level 226Ra from 2 M NaCl solution, Cs+ and Sr2+ from groundwater, demonstrating that it can be immediately used to remedy groundwater and soil contaminated with 226Ra, 90Sr, 137Cs+.
The paper describes the tests carried out for the extraction of radionuclides 90Sr, 137Cs and 60Cо by manganese oxyhydroxide in order to compare the sorption properties of the respective particles with Sr(II), Cо(II), Cе (III), Eu (III) ions. It was found that the recovery efficiency and the sorption capacity with respect to metal ions decrease in the MnOOH → MnO2 → Mn3O4 series. The tests proved that the extraction of the radionuclides from tap water by MnOOH particles was 53.7%, 83.5% and 93.1%, respectively.
Increasing in the use of various radioactive elements in many applications over the past few decades has accompanied with an increase radioactive waste. Therefore, preparation of Al 2 O 3 –ZrO 2 –CeO 2 nanocomposite material by sol-gel polymeric method is carried out. The nanocomposite material was characterized by some analytical techniques such as Fourier transform infrared (FTIR), Thermograviemtric & differential thermal analysis (TGA & DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Separation of ¹³⁴ Cs and ⁹⁰ Sr/ ⁹⁰ Y as a fission product present in radioactive waste effluents using the prepared nanocomposite was investigated. The result showed that removal of 94%, 44% and 8.5% for ¹³⁴ Cs, ⁹⁰ Sr and ⁹⁰ Y, respectively. The experimental results are fitted with pseudo-second-order kinetic model. Isotherm models of sorption process are calculated and it can be concluded that the Langmuir model more fitted than Freundlich model. The calculated thermodynamic functions exhibited that sorption behavior of ¹³⁴ Cs and ⁹⁰ Sr ions are spontaneous in nature and the positive value of ΔH o value indicates that the sorption is endothermic. The results demonstrated that the % sorption of ¹³⁴ Cs(I) and ⁹⁰ Sr(II) is sharply decreased in the presence of coexisting ions (Na, Mg and Cr) using nanoparticles of Al 2 O 3 – ZrO 2 –CeO 2 .
A new group of two-dimensional (2D) materials known as MXene has induced great interests in water purification due to their hydrophilic surface and abundant functional groups. Herein, the performance of 2D Ti2CTx MXene material for thorium (Th(IV)) removal is evaluated in detail. Under different storage conditions, Ti2CTx in hydrated form (Ti2CTx-hydrated) exhibits great enhancement in sorption capacity compared to the dry counterpart, mainly due to the larger interlayer space and the easier entry and diffusion of Th(IV) ions. Batch sorption of Th(IV) onto Ti2CTx-hydrated reveals that the sorption process follows the pseudo-second-order kinetic model and Freundlich isothermal adsorption model. The maximum adsorption capacity can reach as high as 213.2 mg g-1 for Ti2CTx-hydrated, much higher than that of most common inorganic sorbents. Moreover, Ti2CTx-hydrated has excellent adsorption selectivity towards Th(IV) in the presence of competing metal ions. Scanning electron microscopy coupled with energy-dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy analysis are performed to characterize the morphology and structure of Ti2CTx before and after the adsorption, and mechanism for Th(IV) removal is proposed to be associated with inner-sphere complexation. The present results illustrate that Ti2CTx-hydrated could serve as a promising candidate for thorium preconcentration and separation.
We aim to recycle and utilization of eggshell as a biomass waste of human foodstuff. Pure hydroxyapatite nano-particles were prepared using waste eggshell at different temperature of 80 °C (ESHANP) and calcination at the 850 °C (CESHA) adsorbent materials and characterized by some instruments. Sorption studies of ⁶⁰Co and ¹⁰⁹Cd from aqueous waste solutions onto ESHANP and CESHA were performed at different pH solutions, initial ion concentration and contact time. The obtained data were analyzed using some kinetic, diffusion and isotherm models. It can be recommended ESHANP as remediation agent for nuclear waste sites.
In this study an efficient nanomaterial has been developed for the removal of Co(II), Zn(II), Cd(II), Pb(II), Cu(II), Hg(II) ions and radionuclides from water using synthesized nanozerovalent iron (NZVI). To protect NZVI and enhance the adsorption capacity, it was then modified with diethylenetriamine (DETA) followed by functionalization using 2-pyridenecarboxaldehyde (PY). The efficiency of synthesized nanocomposite (NZVI-DETA-PY) for Co(II) was 2600 μmol g⁻¹ at pH 6.0, while for Cu(II), Zn(II), Hg(II), Cd(II) and Pb(II) were 4750, 5600, 5200, 4050 and 4950 μmol g⁻¹ at pH 7. NZVI-DETA-PY was applied in removal of Co(II), Zn(II), Cd(II), Pb(II), Cu(II), Hg(II) and radionuclides from real water matrix (tap water, sea water wastewater and simulated radioactive wastewater) and the percent removal range 90–100%. The adsorption data were examined by different kinetic and isotherm models to analyze the adsorption mechanisms and it was found that Cd(II) and Pb(II) obeyed the pseudo-first order, Co(II), Cu(II), Hg(II) and Zn(II) followed the pseudo-second order. It was also found that Co(II), Cu(II), Cd(II) and Hg(II) obeyed the Temkin model, while Zn(II) fitted with the Langmuir and Pb(II) was most suitable by the DR model. The newly investigated NZVI-DETA-PY nanocomposite was successfully regenerated in this study.
Functionalized magnetic graphene oxide nanoribbons (MGONRs) composite material was synthesized by hydrothermal treatment method using graphene oxide nanoribbons as raw material, which was formed by longitudinal unzipping of multi-walled carbon nanotubes in oxidizing environment. The morphology and structural properties of MGONRs were characterized by SEM, FT-IR, XRD and VSM and thorium adsorption behavior on MGONRs was investigated. The results showed that thorium adsorption on MGONRs was pH-dependent, endothermic and spontaneous. The adsorption process followed pseudo-second order and Freundlich isotherm model with rapid solid–liquid separation. MGONRs could have practical application in separation and recovery of thorium from aqueous solutions.
Bismuth functionalized graphene oxide (Bi-GO) was successfully synthesized and showed both high iodide and iodate removal efficiency from radioactive wastewater. Batch experiments for kinetic and selectivity tests were performed, respectively. Additional SEM, XRD, FT-IR, and XPS analyses were used for characterization of sorbent and bismuth on the GO surface, and confirmed that bismuth on the GO surface reacted with iodine species by surface complexation (or precipitation). Dominant surface species are BiOI and Bi(IO3)3 for iodide and iodate removal, respectively. After the selectivity test using a KCl background solution with varying concentrations, Bi-GO still showed higher removal efficiencies (≥ 95%) for both iodide and iodate than the commercial silver exchanged zeolite (≥ 95% for iodide and ≤ 25% for iodate). Our study provides a potential role of Bi on graphene-based materials for selective removal of both iodide and iodate from radioactive wastewater.
A CNT-modified composite (namely, NH2-PZS/CNT/Fe3O4) was prepared and used for the removal of U(VI) from aqueous solution. The composite was synthesized using Fe3O4 nanoparticles with polyphosphazene-based polymer coating on CNTs. Experiments were carried out to investigate the influence of pH, concentration, contact time and temperature on the U(VI) removal process. The maximum adsorption capacity was calculated as 250 mg/g by considering Langmuir isotherm model and the adsorption process was also explained with pseudo-second-order kinetics. Adsorption tests in the presence of competing ions exhibited high selectivity for U(VI). The thermodynamic parameters indicate that the process was spontaneous and endothermic. The interaction mechanism of U(VI) with NH2-PZS/CNT/Fe3O4 was systematically clarified by using X-ray photoelectron spectroscopy (XPS) and Fourier transformation infrared (FTIR). Overall, the prepared NH2-PZS/CNT/Fe3O4 composite, which displayed important advantages such as re-usability, high adsorption capacity and selectivity, is a good adsorbent candidate for the removal of U(VI) from wastewater.
Co-sorption of anionic and cationic radioactive nuclides is highly desired towards the total cleaning of radioactive contaminated wastewater. A 2D/2D multifunctional nanocomposite of MgAl-LDH/graphene oxide (GO) was fabricated using coagulation and applied for the co-sorption of Sr2+ and SeO42- from aqueous solution. The co-sorption of Sr2+ and SeO42- was synergetically enhanced with the co-presence of each species and showed a maximum Sr2+ removal of 2.435 mmol/g of GO. The synergetic effect occurs only in the MgAl-LDH/GO nanocomposite because of the synchronized effect of MgAl-LDH, GO and alkaline cations, which was not present in pure GO. The SeO42- removal occurred by the interchange of NO3- anion from the LDH, while the removal of Sr2+ occurred through coordination with carboxyl/alkoxy (–COO-/-CO-) groups in GO by the ring opening of epoxides. The co-sorption efficiencies of Sr2+ and SeO42- were stable in the wide pH range of 4-10. The binary (Na2SeO4 + SrCl2) and ternary (Na2SeO4 + SrCl2 + M+/M2+ = other metal ions or An- = other negative ions) systems enhanced the co-sorption of Sr2+ and SeO42- in the presence of other alkali and alkali earth metals and other anions compared with the single system. The Sr2+ and SeO42- sorption densities were superior to previously reported values. The combined multifunctional ability and environmentally benign nature of the MgAl-LDH/GO composite is promising as sustainable materials for the total remediation of Sr2+ and SeO42- a radioactive surrogates and can also be extended to wide combinations of divalent anions and cations.
In this work, multifunctional Fe-aminoclay (FeAC)/carboxymethyl cellulose (CMC)/ polyhedral oligomeric silsesquioxane (POSS) composite (FeAC/CMC/POSS) with layered structure was successfully synthesized and utilized as adsorbent for the removal of cesium ions (Cs+) and cationic dyes methylene blue (MB) and chrysoidine G (CG) from aqueous solutions. The FeAC/CMC/POSS exhibit excellent adsorption capacities for Cs+ ions, MB and CG of 152, 438 and 791 mg g-1, respectively. The adsorption capacities for Cs+ ions, MB and CG are substantially greater than those of many previously reported adsorbents due to (i) the layered morphology of the composite and abundance of amino (–NH2) groups on clay surface; (ii) existence of carboxylate (–COO-) and hydroxyl (–OH-) groups on the CMC backbone, which contribute to the adsorption of large number of Cs+ ions and dye molecules through electrostatic attraction and ion exchange process. More importantly, the incorporation of POSS increases the interlayer spacing of Fe-aminoclay by intercalation providing room for the encapsulation of Cs+ ions and dye molecules. Owing to its unprecedented adsorption capacity, the devised FeAC/CMC/POSS composite could be a promising organic-inorganic material used to cost-effectively remove the multitude of environmental pollutants.
The removal of radionuclides on natural inorganic materials is pursuing issue for many nuclear-related processes requiring remediation of radioactive wastewater. However, the current natural adsorbents with low-cost and great biocompatibility are suffered from limitations in removal efficiency, regeneration capability, or/and operation conditions. Herein, silicon dioxide (SiO2) as the major ingredient of clay minerals was modified by carboxyl groups to improve its adsorption affinity for high-valent radionuclides. The batch experiments for U(VI) capture showed that the carboxyl-modified mesoporous silica (SiO2-COOH) microspheres had fast sorption velocity and were exceptionally capable in efficiently sequestering U(VI) under various relevant interferences. The resulting SiO2-COOH possessed the great potential for controlled loading of high-valent radionuclides in a selective adsorption order of U(VI) > Th(IV) > trivalent ions > divalent ions > Cs(I). The XPS and EXAFS analyses further confirmed that the interaction mechanism between SiO2-COOH and U(VI) was mainly attributed to the inner-sphere complexation with one or two oxygen atoms shared between the UO22+ and the carboxyl ligand. Carboxyl group modification of natural inorganic materials provides a general and powerful approach to eliminate high-valent radionuclides in various wastewater systems.
Uranium is the most radioactive element using in the nuclear industry and nuclear technology application. However, it is harmful for environment and human health due to its high toxicity and mobility. Thus designing effective material for uranium removal is highly desirable. In this paper, a novel adsorbent of [email protected] prepared by anchoring nZVI on Zn-MOF-74 was investigated for the removal of uranium from aqueous solutions. Impressively, nZVI was synthesized for the first time by a spraying approach in a simple and convenient manner. The experimental results indicated that [email protected] can significantly enhance the removal of U(VI) than both Zn-MOF-74 material and nZVI, leading to high adsorption capacity up to 348 mg/g at pH = 3 and 298 K. The origin, as unveiled by XPS, is due to both U(VI) adsorption from Zn-MOF-74 and U(VI)-to-U(IV) reduction by nZVI.
A novel metal sulfide (KZTS) adsorbent has been synthesized using a simple one-step hydrothermal method for radioactive Sr²⁺ removal from aqueous solutions. XRD and TG analyses indicated that KZTS was chemically and thermally stable. SEM-EDS and TEM images showed that KZTS possessed both flake-like and polyhedral structure with the formula of K1.67Zn0.67Sn2.17S6.00 and K5.84Zn3.47Sn5.04S16.99, respectively. The average formula was determined to be K1.87ZnSn1.68S5.30 using ICP-OES. The adsorption ability of KZTS for Sr²⁺ was evaluated in detail by batch experiments. The kinetics studies showed that Sr²⁺ was rapidly removed from the aqueous solution within the equilibrium time of 10 min. According to Langmuir isotherm, the maximum adsorption capacity of KZTS was 19.3 mg/g at 298 K and the high value of the Langmuir constant indicated the high affinity of KZTS for Sr²⁺. The adsorption mechanisms involved ion exchange and surface Sr–S bonding interactions, with the former dominating. High adsorption performance was observed over a broad pH range of 3–11, although it could be inhibited by co-existing ions, especially Ca²⁺ and Mg²⁺. The adsorbent showed a high distribution coefficient (Kd = 1.26 × 10⁶ mL/g) and negligible adsorbate leaching at low Sr²⁺ concentrations, indicating the strong and irreversible adsorption of Sr²⁺ on KZTS. Further, KZTS exhibited high selectivity for Sr²⁺ in alkaline and tap water. These remarkable features suggest that KZTS is a highly desirable adsorbent to remove radioactive strontium from radioactive wastewater.
Three synthetic hematite (SH) materials as iron oxides nanofibers were prepared and applied for the removal of ⁵¹Cr and radioiodine (¹³¹I) as anions associated with nuclear industry technology. The results exhibited that 70% of Cr(VI) and 90% of ¹³¹I were removed from aqueous solution using the SH1 adsorbent. In acid solutions, R % of Cr(VI) increased to > 90% with the decrease in concentration till 0.05M, while the R % of ¹³¹I was 94 and 79% at HNO3 and HCl, respectively. It was concluded that SH1 nanofibers is promising and selective adsorbent for Cr(VI) and ¹³¹I removal from aqueous or acid solutions.
In this study, a novel magnetic core–dual shell Fe3O4@PDA@TiO2 adsorbents was successively prepared by polydopamine (PDA) coated and TiO2 film deposited on the surface of Fe3O4. The structure and properties were characterized by FT-IR, SEM–EDS TEM, VSM and XPS. The adsorption of U(VI) on Fe3O4@PDA@TiO2 was investigated as a function of contact time, solution pH, initial U(VI) concentration and other interfering ions. In addition, the U(VI) adsorption from practical wastewater and simulated seawater was also investigated. The results implied that the Fe3O4@PDA@TiO2 adsorbents exhibited promising adsorption performance for uranium (VI) from aqueous solution and simulated seawater.
With the widespread application of radionuclide ²³⁵U(VI), it is inevitable that part of U(VI) is released into the natural environment. The potential toxicity and irreversibility impact on the natural environment has become one of the most forefront pollution problems in nuclear energy utilization. In this work, rod-like metal-organic framework (MOF-5) nanomaterial was synthesized by a solvothermal method and applied to efficiently adsorb U(VI) from aqueous solutions. The batch experimental results showed that the sorption of U(VI) on MOF-5 was strongly dependent on pH and independent of ionic strength, indicating that the dominant interaction mechanism was inner-sphere surface complexation and electrostatic interaction. The maximum sorption capacity of U(VI) on MOF-5 was 237.0 mg/g at pH 5.0 and T = 298 K, and the sorption equilibrium reached within 5 min. The thermodynamic parameters indicated that the removal of U(VI) on MOF-5 was a spontaneous and endothermic process. Additionally, the FT-IR and XPS analyses implied that the high sorption capacity of U(VI) on MOF-5 was mainly attributed to the abundant oxygen-containing functional groups (i.e., C–O and C[dbnd]O). Such a facile preparation method and efficient removal performance highlighted the application of MOF-5 as a candidate for rapid and efficient radionuclide contamination's elimination in practical applications.
Layered double hydroxides (LDHs), one of the most important two-dimensional layered compounds, have enabled massive developments in effective pollution treatments. Their derivative materials have also attracted multidisciplinary attention owing to the intrinsic advantages of their moderate chemiostability, low cost and nontoxicity. Over the past few decades, significant advances have been made in the synthesis of novel LDH-based composites and the optimization of characterization techniques. In this review, we give an overview of the recent advances in LDH-based nanomaterials, from a brief introduction to their preparation and modification methods to an overview of their application in the removal of radionuclides and an exploration of their underlying adsorption mechanisms. In the end, a summary and outlook are also briefly addressed. This review intends to provide deep insight into the design of high-performance LDH-based materials for the potential elimination of radionuclides from aqueous solutions during environmental pollution cleanup.
The Prussian blue functionalized SiO2 (nano-material of SiO2-Fe-CN) was successfully prepared using a novel and simple preparation route. The SiO2 nanoparticles were functionalized by amino group by refluxing with (3-Aminopropyl) trimethoxysilane, iron (III) immobilized the modified nanoparticles through interaction with the amino group, finally, SiO2-Fe-CN nanomaterial produced as a result of potassium ferrocyanide addition. SEM, FTIR and XRD techniques were used for detecting the morphology, particle size, different functional groups and the crystal structure of the prepared nano-materials. The sorption potential of nano-material of SiO2-Fe-CN towards cationic and anionic radioisotopes from aqueous and HNO3 solutions were tested using carrier free method. The experimental results showed that nano-material of SiO2-Fe-CN have high effective retention and recovery for ¹³⁴Cs, ⁶⁰Co and ⁹⁹Mo from nuclear liquid waste. Moreover, sorption of ⁹⁰Sr/⁹⁰Y is insignificant using SiO2-Fe-CN nano adsorbent material. It is a promising and efficient nano adsorbent that could be used for upscaling design and application on liquid radioactive waste treatment facility.
Titanate nanostructures are promising materials for their far superior performance in the uptake and immobilization of radioactive cations from wastewater. In this study, core-shell sodium titanate hierarchical nanostructures (C@Na2Ti3O7·9H2O, CSTHNs) were fabricated through a combination method (chemical deposition and hydrothermal reaction). The Brunauer-Emmett-Teller (BET) surface area of the CSTHNs is as high as 205.3 m2/g. CSTHNs show high removal capacities (Qmax = 5.757 mmol/g, 8.151 mmol/g and 4.846 mmol/g) and large Kd values (103−104 mL/g) for Cs+, UO22+ and Eu3+ species. The ion exchange and inner-sphere complexation are used to explain the ability of CSTHNs to capture radioactive ions. The influence of valence, hardness and radius of cations on the ion exchange process and complexation are also discussed. The structural collapse of the CSTHNs and the irreversible entrapment of the radioactive cations were confirmed. These results indicate that target radionuclides are efficiently concentrated from water and tightly immobilized in the interlayer which is of great significance for the removal and subsequent safe disposal of hazardous radionuclides. This approach may be helpful for the design and fabrication of high performance adsorbents, and may be widely applied in pollution treatments.
Radionuclides with long half-life are toxic, and thereby result in serious threat to human beings and ecological balance. Herein, a simple two-step synthesis method was used to prepare manganese dioxide@polypyrrole (MnO2@PPy) core/shell structures for efficient removal of U(VI) and Eu(III) from aqueous solutions. The adsorption of U(VI) and Eu(III) were investigated under different kinds of experimental conditions. The experimental results suggested that the adsorption of U(VI) and Eu(III) on MnO2@PPy were greatly affected by pH. U(VI) adsorption on MnO2@PPy was independent of ionic strength at pH<6.0, and dependent on ionic strength at pH>6.0. However, Eu(III) adsorption on MnO2@PPy was independent of ionic strength at the whole pH range of experimental conditions. The maximum adsorption capacities (qmax) of U(VI) and Eu(III) were 63.04 and 54.74 mg g⁻¹ at T=298 K, respectively. The BET, XRD, FTIR and XPS analysis evidenced that high adsorption capacities of U (VI) and Eu(III) on MnO2@PPy were mainly due to high surface area and rich metal oxygen-containing group (i.e., Mn–OH and Mn–O), and the interaction was mainly attributed to strong surface complexation and electrostatic interaction. This study highlighted the excellent adsorption performance of U(VI) and Eu(III) on MnO2@PPy and could provide the reference for the elimination of radionuclides in real wastewater management.
Highly efficient removal of metal ion pollutants, such as toxic and nuclear waste-related metal ions, remains a serious task from the biological and environmental standpoint because of their harmful effects on human health and the environment. Recently, highly porous metal–organic frameworks (MOFs), with excellent chemical stability and abundant functional groups, have represented a new addition to the area of capturing various types of hazardous metal ion pollutants. This review focuses on recent progress in reported MOFs and MOF-based composites as superior adsorbents for the efficient removal of toxic and nuclear waste-related metal ions. Aspects related to the interaction mechanisms between metal ions and MOF-based materials are systematically summarized, including macroscopic batch experiments, microscopic spectroscopy analysis, and theoretical calculations. The adsorption properties of various MOF-based materials are assessed and compared with those of other widely used adsorbents. Finally, we propose our personal insights into future research opportunities and challenges in the hope of stimulating more researchers to engage in this new field of MOF-based materials for environmental pollution management.
In recent years, sustainable nanomaterials, such as cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs); jointly referred to as cellulose nanomaterials (CNs) have been explored for application in water/wastewater treatment processes. Unique properties of CNs coupled with the global quest to develop low carbon footprint alternatives as aids for water treatment processes have been the driving force for this increasing interest among researchers worldwide. There are several reviews that describe the chemistry and modification of CNs; however, a comprehensive review on the potential application of CNs in water/wastewater treatment processes is scarce. Thus, this review provides a detailed overview on pristine, surface functionalized CNs and CN incorporated nanocomposites for applications in various water/wastewater treatment processes, such as sorption, membrane filtration, and flocculation. The latest advances and developments on other systems using CNs, such as catalytic degradation and disinfection are also discussed, and the mechanism responsible for the performance of CN based systems in water treatment processes was elucidated. The key challenges and knowledge gaps that limit the practical application of CNs in water treatment processes are examined, which offer appropriate perspectives to researchers working in this field.
A newly developed adsorbent nano Cu2O/Cu-modified activated carbon composite (nano Cu2O/Cu-C) was used to remove radioactive iodide ions (I-) from simulated wastewater. The emphasis of this research is to improve adsorption performance and obtain higher I- removal efficiency compared with the single-stage adsorption. To fully develop the amount of adsorption by nano Cu2O/Cu-C, and to increase the decontamination factor (DF) of I-, an improved countercurrent two-stage adsorption (ICTA) process was introduced. In the ICTA process, measures dealing with desorption of loaded adsorbent in the stage-two adsorption were taken and more extensive application of countercurrent two-stage adsorption (CTA) process could be made after the improvement to ICTA process in this study. Furthermore, in order to analyze the process and determine the I- concentration in the effluent, a calculation method was devised based on the Langmuir isotherm equations and adsorption accumulation principle. The mean DFs were 177, 166, and 89.7, respectively, when the initial I- concentrations were 5.00, 10.0, and 20.0 mg/L; and the adsorbent dosage was 1.25 g/L. These results were approximately 8.76, 8.97, and 6.79 times higher, respectively, than with conventional single-stage adsorption. The experimental values of the I- concentration were higher than the calculated ones, which could be ascribed to desorption of the residual loaded adsorbent and formation of CuI in the adsorption at stage 1. Formation of CuI in the adsorption at stage 1 was considered to be the predominant reason.