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In this study, the use of magnetic biochar particles recovered from biorefinery by-products (humins) for adsorption of hydrophilic organic pollutants was investigated. The biochar was prepared by thermal treatment of crude humins followed by a grinding step after which a magnetic iron oxide was co-precipitated on the biochar surface. The resulting...
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The surface flat pristine biochar provides limited adsorption sites for Cd(II) adsorption. To address this issue, a novel sludge-derived biochar (MNBC) was prepared by NaHCO3 activation and KMnO4 modification. The batch adsorption experiments illustrated that the maximum adsorption capacity of MNBC was twice that of pristine biochar and reached equ...
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... The SEM images of Fe 3 O 4 /BC (Fig. 2c-d) low pressure, revealing the high microporosity in Fig. 3a. The hysteresis loop appeared when the relative pressure of BC was greater than 0.2, which was mainly caused by the mixed presence of micropores and mesopores [30]. Therefore, it could be concluded that BC was a graded porous material with micropores and mesopores. ...
Matrix complete dissolution combined with magnetic solid-phase extraction (MSPE) was applied to extract four benzotriazole ultraviolet stabilizers (BUVSs) from polyester curtains. Ultra-performance liquid chromatography tandem mass spectrometry was coupled to perform the content of trace BUVSs. The procedure was being developed in two steps. The polymer matrix was initially thoroughly dissolved by 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) followed by the addition of precipitant to separate the target from the dissolved polymer matrix. Next, triiron tetraoxide/biochar magnetic material was prepared and utilized as the sorbent for purification of the extract. Ultrasonic extraction coupled with the MSPE method and the proposed method was compared. Better extraction recovery of four BUVSs was acquired by the novel developed extraction method. The purification effect of the new extraction method was established by comparing the matrix effect of the polymer complete dissolution method and the polymer complete dissolution combined with the MSPE method. The extraction parameters were investigated. Under the optimized conditions, correlation coefficient (r) ranging from 0.9969 to 0.9997, limit of detection of 0.2 to 0.8 ng·g⁻¹, and the recovery varied from 81.5 to 102.7% with RSD smaller than 10.7% were obtained for four BUVSs, respectively. This study provides a potential strategy for the efficient extraction and sensitive determination of BUVSs in polyester fibers samples.
Graphical Abstract
... For example, chemical harshness can come in the form of corrosive wastewaters (Shokri & Fard, 2022) or highly acidic wastewaters (Meng et al., 2020). Physical harshness can be encountered in the form of strong hydrodynamic forces acting on the adsorbent's structure (Lomenech et al., 2021;Mudhoo, Patel, Mohan, Pittman, & Sillanp€ a€ a, 2021). Such harsh conditions may thus induce permanent structural damage (e.g. ...
Pore network, pore connectivity and the resulting effective adsorbate pore diffusivity within an adsorbent are critical physical considerations in mass transport modelling of aqueous adsorption. Tied to these three adsorbent features are the adsorbent tortuosity and tortuosity factor concepts. These concepts encompass the collective hindrance to intra-adsorbent adsorbate transport arising because of a disorderly adsorbent porous topology. It is crucial to the materials scientist, chemist, chemical engineer and water treatment specialist to understand the complex and variable connections among adsorbate chemistry, adsorbent chemistry, adsorbent porosity, pore shape, size and tortuosity, pore wall effect, adsorbate-adsorbent and adsorbate-adsorbate interactions in competitive contaminated aqueous environments.
Adsorbent tortuosity has been sporadically studied in aqueous adsorption models. Despite the slim population of these studies, insightful observations and inferences have been reported. However, as it appears, no review has been published to compile, compare and contrast these aspects. Hence, this review concisely brings up those observations and interpretations around adsorbent tortuosity for aqueous adsorption systems. The notion of an adsorbent’s tortuosity being single-valued is argued to be imprecise. Finally, perspectives are aired on possible research and development directions for elucidating the dynamic attributes of adsorbent tortuosity and applying them in real-scale adsorption-oriented water purification. The data acquired by filling in these research gaps can enable the design of adsorbents more adapted for real-scale water purification.
... The adsorption capacity of P-H-0.5 tends to be stable when pH > 5, while P-2-H-2 still slightly increases, indicating that the two-step sample is more acidic and more sensitive to pH [14,53]. The surfaces of both samples are negatively charged when pH > pH PZC (insets), whereas in the relatively acidic (pH < pH PZC ) system, MB molecules mainly undergo protonation [54]. Thereafter, with increasing pH, deprotonation dominates and the proportion of cation in the dye molecule gradually rises. ...
... Both the Langmuir and Freundlich isotherm models match with the sorption data, yet the former fit is obviously better (Figure 11b,d, and Table 3). This means the adsorption by the two samples is relatively uniform and monolayer [54]. The calculated RL values (Supplementary Material) range from 0.00034-0.001 ...
Extensive research has demonstrated the advantageous utilization of medium–low temperature fast pyrolysis (FP) for biomass, yielding high–grade liquid–phase chemicals or fuels. However, the field of FP–based high–performance solid biochar research still presents several gaps. Herein, a one–step versus two–step method for biomass H3PO4 activation under FP was comparatively analyzed for the first time, and efficiently activated carbons (ACs) for dye removal were successfully synthesized at a low temperature (723 K). Investigation of methylene blue (MB) adsorption revealed that the one–step sample P–H–0.5, possessing a specific surface area of 1004 m2·g−1, exhibited a remarkable adsorption capacity of 695.54 mg·g−1 with an ultra–high removal rate (99.94%, C0 = 150 mg·L−1). The two–step sample P–2–H–2, a modified byproduct of FP, achieved efficient dye adsorption in the shortest time (2 min, 383.91 mg·g−1). This originated from the well–developed surface macropores and elevated group content derived from phosphorus (P)—modification. Both adsorption data were well–fitted with pseudo–second–order kinetics and the Langmuir model, revealing the presence of chemical effects and the dominance of monolayer adsorption. A more detailed kinetic study suggested intrapore transport primarily governed the adsorption process on P–H–0.5, whereas P–2–H–2 relied on surface diffusion. FTIR and XPS revealed notable differences in the active sites between the two methods. Aside from –OH, –COOH with C–O–P, the P elements of P–H–0.5 were classified as C–P–O3 and C2–O–P2, demonstrating the ability of one–step FP to introduce heteroatoms into carbon defects. The basic interactions of ACs with MB were π–π stacking and hydrogen bonding established by –OH–containing groups. At a suitable pH (>5), most H+ was removed from the surface, and the electrostatic attraction became the strongest linking force. Both ACs exhibited exceptional reusability, with removal rates surpassing 90% of the initial rate after four cycles of regeneration.
... The presence of negatively charged carboxylate groups on the surface of PTONB were primarily responsible for its great dispersion stability, which reflect particles' ability to repulse each other electrostatically, and effective surface charge density [40]. The negative surface charge on PTONB is more effective on the removal of heavy metal cations and cationic organic dyes through electrostatic adsorption [41][42][43]. ...
The transformation of agro-waste into biochar using thermochemical processes aids in the management and disposal of biomass with the potential to provide significant energy. Different biochars exhibit different characteristics and performances depending on the fabrication method employed. Besides, many applications, such as remediation to adsorb heavy metals which favor biochars rich with oxygen-containing functional groups on their surface. Therefore, this study deals with the catalytic carbonization of the rachis part in windmill palm trees with ferrocene at different temperatures (300, 350, 450, and 500 °C), time intervals (25, 40, and 90 min.), and ratios (3:1, 3:2, and 3:3 palm tree: ferrocene ratio) to produce oxidized nanobiochar. The highest electronegativity’s (− 61.8 and − 64 mV) for PTONB were observed when samples were prepared at 350 °C, 90 min., 3:1 PT: F and 350 °C, 25 min., 3:2 PT: F, respectively. Morphological analysis showed that, the carbonization of windmill palm tree at 350 °C, 90 min. without ferrocene give spherical nano-biochar with bulky particle size of 237 nm. However, after ferrocene treatment, the nanobiochar particle size was reduced, ranging from 87 to 3 nm. Thus, the ferrocene/palm tree catalytic carbonization process is highly relevant to decreasing particle sizes. Consequently, based on the findings from physicochemical analyses (e.g., SEM-EDX, ATR-FTIR, X-ray diffraction, and high-resolution TEM), a straightforward and rapid method to synthesize an oxidized nano-biochar, with a wide variety of structural characterizations, at a low temperature in a single step under a muffled atmosphere has been developed.
Graphical Abstract
... Formerly, the pristine biochar is prepared and undergoes co-precipitation of magnetic particles onto the biochar matrix. Lomenech et al. (2021) prepared humin-derived biochar by heating it at 250°C for one hour and then its magnetic composite was formed by dissolving it in FeCl 3 and FeSO 4 solutions. The magnetic biochar is suspended in NaOH solution for the precipitation of iron oxide nanoparticles on its surface. ...
Dyes are extensively used in textile, leather accessories, paper, paint, printing, furniture, food, and plastic products. Release of untreated dyes causes adverse effects on environment. Different physical and biological treatments are inefficient to treat dyes. In this regard, photocatalysis using nanoparticles has emerged as an efficient method for degradation of the dyes. TiO2, Fe2O3, and ZnO under UV or sunlight exposure are used as nano-photocatalysts. These nano-photocatalysts have potential to convert toxic pollutants into simpler end products such as CO2 and H2O without generation of secondary pollutants. Photocatalytic degradation of dyes is mainly affected by concentration of dye, amount of photocatalyst, intensity of irradiated light, time of irradiation, and effect of dissolved oxygen and pH. Biochar has emerged as an eco-friendly, cost-effective, and multi-functional product prepared from thermo-chemical conversion of different biomass-based wastes. Physico-chemical properties of biochar enable it to support various light-active components with easy isolation and recovery of catalyst. Incorporation of biochar with nano-photocatalyst provides enhanced porosity, specific surface area, number of active sites, chemical stability, charge separation, and photocatalytic efficiency. The present chapter focuses on fundamentals of photocatalytic process, synthesis of biochar supported nano-photocatalysts, their application for removal of dyes, mechanism involved, and future prospects.KeywordsBiocharDyesNanoparticlesNano-photocatalystPhotocatalysis
... Formerly, the pristine biochar is prepared and undergoes co-precipitation of magnetic particles onto the biochar matrix. Lomenech et al. (2021) prepared humin-derived biochar by heating it at 250°C for one hour and then its magnetic composite was formed by dissolving it in FeCl 3 and FeSO 4 solutions. The magnetic biochar is suspended in NaOH solution for the precipitation of iron oxide nanoparticles on its surface. ...
Biochar is a solid carbonaceous pyrolyzed product prepared from various lignocellulosic biomass (agriculture and crop residues), sewage sludge, waste products obtained from different sources, litters, animal manures, etc., under limited oxygen conditions. In recent times, biochar applications in soil remediation, removal of hazardous organic and inorganic contaminants, wastewater treatment, electrode material, catalysis, etc., have drawn worldwide curiosity because of its unique properties. Instead of having unique properties, biochar application range is still limited due to its heterogeneous surface functionality, low porosity, and less adsorption capacity. The physicochemical properties of carbonaceous materials can be improved through various physical and chemical techniques, and biochar may be a better carbonaceous material due to its inexpensive and easy production process. Among physical modification techniques, steam activation is an environmentally and economically sustainable easy modification technique free from the use of any chemicals. With the advancement of nanotechnology, nanoscale engineering of biochar has captured care from scientific societies due to its nano-sized fabrication with excellent physical, chemical, and surface properties. Various mechanochemical techniques such as ball milling, microwave irradiation, and magnetic modification are vastly used for the nanoscale fabrication of biochar materials. Nanoscale engineering further increases the stability and efficiency of raw biochar material over physical modification techniques. This chapter includes steam activation used for physical activation of biochar as well as three selected mechanochemical techniques, viz. ball milling, microwave irradiation, and magnetic modification used for nanoscale modification of biochar along with their application in various fields. Biochar modification and its fabrication into nanoscale form is not only a novel approach but also provides a more advanced and efficient waste management technique.KeywordsBall millingMagnetic modificationsMicrowave irradiationModification of biocharNano-biochar materialsSteam activation
... Formerly, the pristine biochar is prepared and undergoes co-precipitation of magnetic particles onto the biochar matrix. Lomenech et al. (2021) prepared humin-derived biochar by heating it at 250°C for one hour and then its magnetic composite was formed by dissolving it in FeCl 3 and FeSO 4 solutions. The magnetic biochar is suspended in NaOH solution for the precipitation of iron oxide nanoparticles on its surface. ...
Growing demand for foods for billions of hungry mouths is imitating high-yielding crop production which needs the application of an enormous amount of chemicals. Several human activities in recent years for societal development are also on the front foot. These agricultural activities coupled with non-systematic societal development create serious environmental pollution. Many technologies have been developed by impregnating biochar with hydrogel composites, as a sorbent to remove pollutants from water and soil. Biochar is a stable carbon-dominant material with porous structure, high surface area, developed pore structure, and low cost, which ensure its applicability as a porous absorbent. Agricultural waste biomass can be successfully converted into biochar by pyrolysis or thermochemical conversion technique. On the other hand, hydrogels are three-dimensional hydrophilic polymer molecules that can accommodate a significant fraction of fluids in their swelling form. Due to its unique bio-degradability, biocompatibility, and water retention properties, hydrogels are used as a carrier of biochar-based compounds to remediate environmental pollution. The formation of the biochar hydrogel composite systems could synergistically improve the inherent property of the sorbent system for the removal of contaminants. The most beneficial use of hydrogel-biochar nanocomposites is to remove the organic contaminant and toxic elements including chromium, arsenic, mercury, and lead in the aquatic environment via simultaneous adsorption and degradation. Most importantly, these composites contribute to waste management, climate change mitigation, and improving soil fertility. Water contaminants like phenol, dyes, and pharmaceutical hazardous compounds are effectively degraded by biochar-supported photocatalysts. In this chapter, an overview of current progress in the preparation of biochar-loaded hydrogel composites system is provided along with the potential application for removing the unwanted environmental threat. Herein, the chapter begins with a fundamental environmental contaminant and their effect on social ecosystem. We provide the basic information regarding practical information of biochar-based nanocomposites in the treatment of environmental contaminants.KeywordsBiodegradabilityBio-compatibilityEnvironmental contaminantHeavy metalPorous structureSurface areaWater treatment
... As presented in Fig. 3B, the surface of the biochar is covered with iron oxide microparticles, among which spherically shaped ones predominate (Zhang et al., 2016). The iron oxide nanoparticles are not distributed homogeneously on the biochar surface, but rather form islands, which is common for hybrid biochar/iron oxide materials (Lomenech et al., 2021). ...
Raspberry stalks-derived biochar (BC), magnetic biochar-iron oxide composite (BC–Fe) and its derivative modified with urea (BC–Fe–U) were synthesized, characterized and tested as(V) and Cr(VI) ion sorbents. The surface area of BC, BC-Fe and BC-Fe-U was 259, 163 and 117 m² g⁻¹, respectively. The structure of BC was dominated by micropores, while in BC-Fe and BC-Fe-U mesopores predominated. Based on the XRD results, it was found that the magnetic properties of the biochar-iron oxide composites are due to the presence of ferrimagnetic magnetite (Fe3O4) and maghemite (Fe2O3). The optimal pH of As(V) and Cr(VI) adsorption onto the studied sorbents is in the range of 2.3–5.7. Pristine biochar (BC) does not adsorb As(V) ions; however, it enables rapid adsorption of Cr(VI) with the static adsorption capacity of 19.2 mg g⁻¹. The maximum static adsorption capacities of As(V) and Cr(VI) ions onto BC-Fe and BC-Fe-U are within the range of 13.5–16.3 mg g⁻¹. For most adsorption systems tested, adsorption equilibrium is reached within 4 h, though even a few minutes is enough to reach half of the adsorption static value. Phosphates over 0.005 mol L⁻¹ hinder adsorption of As(V) and Cr(VI) ions. Application of at least 5 mol L⁻¹ nitric acid allows about 95% of Cr(VI) and As(V) to be desorbed from adsorbate-loaded BC-Fe material. For other materials, the desorption efficiencies are significantly lower. BC-Fe and BC-Fe-U materials were successfully used for simultaneous Cr(VI) and As(V) removal from river water.
... Digestion of residual biomass by microbes or bacteria to produce biogas or enzymes also attracted high attention since the production costs are low. Valorization of residual biomass as biofuels [3,4], biogas [5,6], biosorbent [7,8], biochar [9,10] and biopesticides [11,12] was also investigated, as well as reuse of residual biomass as soil amendment [13,14], organic mulch [15] and animal feed [16]. ...
Lavandin hydrochars obtained by hydrothermal carbonization (HTC) of Lavandula distilled straw (LDS) have been studied as an eco-friendly and economical valorization route of residual biomass from cosmetic industry into solid fuels. The critical parameters of the HTC process (temperature and retention time) were normalized to severity factor (SF). Proximate and ultimate analysis, microscopy and thermal analysis were used to characterize hydrochars surface, combustion behavior and kinetics as a function of SF, and to compare them with those of the raw lavandin sample. Results showed that preparation of lavandin hydrochars in temperature and retention time conditions providing SF close to 6 seemed to be the best compromise since under these conditions, the combustion performance of the hydrochar was close to the bituminous coal and lignite.
... Magnetic modification of biochar provides a feasible solution to overcome these drawbacks (Ahmed et al., 2021b). There are a lot of magnetic biochars for water purification (Chen et al., 2011;Wang et al., 2018;Zhang et al., 2015;Li et al., 2020;Lomenech et al., 2021;Nie et al., 2021;Zahedifar et al., 2021), but only a few used for uranium removal. Recently, there have been studies of using magnetized biochar, including iron nanoparticles in silicon-containing biochar (Sen et al., 2021), biochar derived from Tribulus terrestris (Ahmed et al., 2021b), Citrullus lanatus L. seeds biochar (Ahmed et al., 2021a), nano zero-valent iron-activated biochar (Zhang et al., 2021), and others (Thines et al., 2017;Nie et al., 2021) for removal of U(VI). ...
Biosorption using modified biochar has been increasingly adopted for the sustainable removal of uranium-contaminated from an aqueous solution. In this research study, the facile preparation and surface characteristics of magnetized biochar derived from waste watermelon rind to treat U(VI) contaminated water were investigated. The porosity, specific surface area, adsorption capacity, reusability, and stability were effectively improved after the magnetization of biochar. The kinetics and isotherm studies found that the U(VI) adsorption was rate-limiting monolayer sorption on the homogeneous surface of magnetized watermelon rind biochar (MWBC). The maximum adsorption capacity was found to be 323.56 mg of U(VI) per g of MWBC at pH 4.0 and 293 K that was higher than that of watermelon rind biochar (WBC) (135.86 mg g⁻¹) and other sourced biochars. The surface interaction mechanism, environmental feasibility, applicability for real-filed water treatment studied in the electromagnetic semi-batch column, and reusability of MWBC were also explored. Furthermore, salient raised the ion exchange and complexation action capacity of MWBC due to the presence of Fe oxide. The overall results indicated that MWBC was not only inexpensive and had a high removal capacity for U(VI), but it also easily enabled phase separation from an aqueous solution, with more than three times reusability at a minimum removal capacity of 99%.
