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Occurrence, Behavior and Effects of Nanoparticles in the Environment
Abstract
The increasing use of engineered nanoparticles (NP) in industrial and household applications will very likely lead to the release of such materials into the environment. Assessing the risks of these NP in the environment requires an understanding of their mobility, reactivity, ecotoxicity and persistency. This review presents an overview of the classes of NP relevant to the environment and summarizes their formation, emission, occurrence and fate in the environment. The engineered NP are thereby compared to natural products such as soot and organic colloids. To date only few quantitative analytical techniques for measuring NP in natural systems are available, which results in a serious lack of information about their occurrence in the environment. Results from ecotoxicological studies show that certain NP have effects on organisms under environmental conditions, though mostly at elevated concentrations. The next step towards an assessment of the risks of NP in the environment should therefore be to estimate the exposure to the different NP. It is also important to notice that most NP in technical applications are functionalized and therefore studies using pristine NP may not be relevant for assessing the behavior of the NP actually used.
... A nanoparticle is the most fundamental component in the fabrication of a nanostructure, and is far smaller than the world of everyday objects that are described by Newton's laws of motion, but bigger than an atom or a simple molecule that is governed by quantum mechanics. Nanoparticles (NPs) originated from different sources and can be grouped into natural and anthropogenic (man-made) which, in turn, can be subdivided into accidental and engineered or manufactured nanoparticles or they can be classified further based on chemical composition, into organic (carbon containing) and inorganic (Nowack and Bucheli, 2007). Of particular importance, the optical property is one of the fundamental attractions and a characteristic of a nanoparticle. ...
... So the exposure of humans and other living organisms to nanoscale particles is not as recent as the new field of nanotechnology. Source: (Nowack and Bucheli, 2007) ...
In this work, FTIR spectrometry was used to analyse the spectra configurations on the synthesised silver nanoparticles were synthesized using two different reducing agents (1) sodium borohydride (NaBH 4), at two temperature conditions of 27⁰C and 4⁰C (room temperature and ice cold temperature), and (2) trisodium citrate (3NaCi) at 100⁰C (boiling temperature) by chemical reduction method. The objective of this work is to compare the results of Ag nanoparticles synthesised, using sodium borohydride as reducing agent, at room temperature and after precooling in an ice bath. Secondly, to comparing the results of the synthesized Ag nanoparticles using two different reducing agents and thirdly, to observe the effect of IR spectrophotometer on the nanoparticles in terms of wavelength (m) and absorbance (A) and (transmittance, T). The resulting nano-sized colloids have been characterized by FTIR spectroscopy. A clear and yellow colouration was obtained from all the synthesised samples, which indicates the presence of formed nanoparticles with strong absorption peaks obtained at wave length range of 1370-1380 cm-1 and 840-841 cm-1 proving the presence of silver nanoparticles based on the functional group. The elements found to be present at such peak were the nitro and NO functional groups when compared with the reported literature. The results shows that Ag nanoparticle colloid was formed using sodium borohydride irrespective of temperature, but the synthesis performed at lower temperature yielded more stable colloids.
... During evolution of life, exposure to nanoparticles has been encountered by all, and adoption of tolerance mechanism is a part of this (Buffle 2006). Soil organic and inorganic colloids including nano-sized silt and clay particles, dissolved organic carbon, and sesquioxides all are commonly occurring nanoparticles (Nowack and Bucheli 2007). Incomplete or anaerobic combustion of coal, petroleum products, and even plant parts and plant-derived substances present in soils is of nano-sized substances . ...
... Nanoparticles can affect nutrient transport, pollutant adsorption, and fixation of elements and organic molecules (Mani and Mondal 2016). Weathering of primary minerals also produces nanoparticles like allophane, silicate clays, and amorphous oxides (Nowack and Bucheli 2007). Production of nanoparticles by microorganisms through the use of redox metals by metabolic pathways is another promising source of natural nanoparticles. ...
Nanofertilizers are important in agriculture and agroforestry to boost nutrient use efficiency, lower fertilizer waste, and lower cultivation costs while also enhancing crop growth and yield. Nanofertilizers provide more surface area for different metabolic reactions in the plant which accelerates photosynthesis and increases the amount of dry matter and productivity of crops and trees. Nanofertilizers are particularly useful for precise nutrient management in precision agriculture. According to studies, applying nanofertilizers minimizes soil toxicity, reduces the risk of adverse side effects from overdosing, and increases the nutrient use efficiency. Due to the scarcity of arable land and water, the development of the agricultural sector can only be achieved by improving resource use efficiency through efficient utilization of modern technologies. One of these technologies is nanotechnology, which has the potential to completely transform agricultural systems. Consequently, nanotechnology has a great potential to promote sustainable agriculture, particularly in underdeveloped nations.
... Nanoparticles (NPs) have a larger surface-area-to-volume ratio, increased chemical reactivity, and high stability (Hussain et al., 2010;Dubadi et al., 2023). These characteristics give NPs unique physical, chemical, and biological properties that enhance their use in various applications (Nowack and Bucheli, 2007;Abd El-Ghany et al., 2023). Nanoparticles are incorporated in various fields such as agricultural, biomedical, environmental, and industrial fields (Khan et al., 2019). ...
... Attempts to define nanoplastics have sparked controversy among researchers, mainly due to differences of opinion regarding their size, but the definition of nanoplastics as particles that are produced unintentionally (either through the manufacture of plastic products or their degradation) and are in a colloidal state, with size varying in the range of 1-100 nm [5,50,52], is the relevant one for the current state of knowledge. Nanoplastics are widespread in aquatic ecosystems due to sewage discharge, aerial deposition, spills, and runoff [53] and can be divided into two groups: (a) natural nanoplastics (e.g., aerosols, desert dust, emissions from volcanic activity, etc.) and (b) anthropogenic (e.g., from metal oxides, fossil fuel combustion, vehicle exhaust emissions, drug production, emissions from mining demolitions, etc.) [53][54][55]. The most prevalent type of nanoplastic in the aquatic environment is titanium dioxide (TiO2), which is reported by the European Union to be one of the main pollutants of surface water, with a quantitative proportion of 2.2 µg/L [54]. ...
The aquatic environment encompasses a wide variety of pollutants, from plastics to drug residues, pesticides, food compounds, and other food by-products, and improper disposal of waste is the main cause of the accumulation of toxic substances in water. Monitoring, assessing, and attempting to control the effects of contaminants in the aquatic environment are necessary and essential to protect the environment and thus human and animal health, and the study of aquatic ecotoxicology has become topical. In this respect, zebrafish are used as model organisms to study the bioaccumulation, toxicity, and influence of environmental pollutants due to their structural, functional,
and material advantages. There are many similarities between the metabolism and physiological structures of zebrafish and humans, and the nervous system structure, blood–brain barrier function,
and social behaviour of zebrafish are characteristics that make them an ideal animal model for studying neurotoxicity. The aim of the study was to highlight the neurotoxicity of nanoplastics, microplastics, fipronil, deltamethrin, and rotenone and to highlight the main behavioural, histological, and oxidative status changes produced in zebrafish exposed to them.
Keywords: zebrafish; microplastics; fipronil; deltamethrin; rotenone
... NMs can be formed into a variety of shapes, such as nanofilms, nanowires, nanotubes, and NPs, which can be spherical or rod-shaped. The incorporation of manufactured NMs into products can take place in a variety of ways, including as surface coatings, laminates, or materials dispersed throughout a product's matrix [5,6]. ...
... As a consequence of their extensive applications, they can reach terrestrial compartments through deliberate or unintentional release. Therefore, soils are not only sources of naturally occurring NPs (Nowack and Bucheli 2007;Waychunas et al. 2005), but also one of the major sinks of engineered NPs (Klaine et al. 2008;Rajput et al. 2018). Once in the soil, there is a possibility that engineered NPs accumulate in non-target organisms and exert harmful effects on them (Martínez et al. 2021). ...
Co-exposure soil studies of pollutants are necessary for an appropriate ecological risk assessment. Here, we examined the effects of two-component mixtures of metal oxide nanoparticles (ZnO NPs or goethite NPs) with the insecticide chlorpyrifos (CPF) under laboratory conditions in short-term artificial soil assays using Eisenia andrei earthworms. We characterized NPs and their mixtures by scanning electron microscopy, atomic force microscopy, dynamic light scattering and zeta potential, and evaluated effects on metal accumulation, oxidative stress enzymes, and neurotoxicity related biomarkers in single and combined toxicity assays. Exposure to ZnO NPs increased Zn levels compared to control in single and combined exposure (ZnO NPs + CPF) at 72 h and 7 days, respectively. In contrast, there was no indication of Fe increase in organisms exposed to goethite NPs. One of the most notable effects on oxidative stress biomarkers was produced by single exposure to goethite NPs, showing that the worms were more sensitive to goethite NPs than to ZnO NPs. Acetylcholinesterase and carboxylesterase activities indicated that ZnO NPs alone were not neurotoxic to earthworms, but similar degrees of inhibition were observed after single CPF and ZnO NPs + CPF exposure. Differences between single and combined exposure were found for catalase and superoxide dismutase (goethite NPs) and for glutathione S-transferase (ZnO NPs) activities, mostly at 72 h. These findings suggest a necessity to evaluate mixtures of NPs with co-existing contaminants in soil, and that the nature of metal oxide NPs and exposure time are relevant factors to be considered when assessing combined toxicity, as it may have an impact on ecotoxicological risk assessment.
... Recently, nanomaterials are considered as the world's most attractive materials due to their potential applications particularly for environmental challenges such as in water treatments [1]. Additionally, the use of nanostructured materials for water treatment processes is a reality and hot issue and thus there are long lists of nanomaterials in the markets [2]. In several studies nanoparticles have been addressed as efficient and effective adsorbents for removal of toxic metals from water systems. ...
This research work has proposed preparation of Scolecite/ZnO nanocomposites (NCs) by a novel aqueous route using Zinc Nitrate Hexahydrate (Zn (NO3)2.6H2O) as a precursor and distilled water were used as solvent without any requirement of calcinations step at high temperature. The comprehensive structural studies carried out using Powder X-Ray diffraction (PXRD) and Fourier Transform Infrared Spectroscopy (FT-IR) PXRD spectrum showed that the ZnO Nanoparticles exhibited crystalline structure. The average crystallite sizes of the prepared NCs calculated by using Debye-Scherrer equation. The sharp peak in the FT-IR spectrum determined the purity of ZnO Nanoparticles
... Zinc oxide nanoparticles (ZnO NPs) are widely utilized in various industrial and biological applications, such as coating, cosmetics, paint, drug delivery systems, and biomedical engineering [1,2]. However, the expanding utilization of ZnO NPs has raised concerns regarding their potential adverse effects on human health and the environment [3,4]. ...
Zinc oxide nanoparticles (ZnO NPs) are widely used in versatile applications, from high technology to household products. While numerous studies have examined the toxic gene profile of ZnO NPs across various tissues, the specific lipid species associated with adverse effects and potential biomarkers remain elusive. In this study, we conducted a liquid chromatography-mass spectrometry based lipidomics analysis to uncover potential lipid biomarkers in human kidney cells following treatment with ZnO NPs. Furthermore, we employed lipid pathway enrichment analysis (LIPEA) to elucidate altered lipid-related signaling pathways. Our results demonstrate that ZnO NPs induce cytotoxicity in renal epithelial cells and modulate lipid species; we identified 64 lipids with a fold change (FC) > 2 and p < 0.01 with corrected p < 0.05 in HK2 cells post-treatment with ZnO NPs. Notably, the altered lipids between control HK2 cells and those treated with ZnO NPs were associated with the sphingolipid, autophagy, and glycerophospholipid pathways. This study unveils novel potential lipid biomarkers of ZnO NP nanotoxicity, representing the first lipidomic profiling of ZnO NPs in human renal epithelial cells.
... 20 Similarly to micropollutants, nanoparticles can bioaccumulate and have been shown to have potentially synergistic interactions, amplifying their toxicity. 21 Supported photocatalysts do not require downstream removal, but lower surface areas result in lower treatment efficiencies. 22 In addition, there are issues of shadowing, where the non-transparent support material blocks irradiation of the photocatalyst. ...
The continuing accumulation of organic micropollutants, particularly pharmaceuticals, in water is now considered an urgent threat to human health and the environment. Although the photocatalytic degradation of these compounds using...
... These organisms are not the direct targets of nanomaterial applications but may be affected due to environmental exposure. For example, nanoparticles may accumulate through the food chain, affecting higher trophic levels [105]. Furthermore, the bioavailability and bioaccumulation of NMs may lead to unintended ecological risks. ...
As global food security faces challenges, enhancing crop yield and stress resistance becomes imperative. This study comprehensively explores the impact of nanomaterials (NMs) on Gramineae plants, with a focus on the effects of various types of nanoparticles, such as iron-based, titanium-containing, zinc, and copper nanoparticles, on plant photosynthesis, chlorophyll content, and antioxidant enzyme activity. We found that the effects of nanoparticles largely depend on their chemical properties, particle size, concentration, and the species and developmental stage of the plant. Under appropriate conditions, specific NMs can promote the root development of Gramineae plants, enhance photosynthesis, and increase chlorophyll content. Notably, iron-based and titanium-containing nanoparticles show significant effects in promoting chlorophyll synthesis and plant growth. However, the impact of nanoparticles on oxidative stress is complex. Under certain conditions, nanoparticles can enhance plants’ antioxidant enzyme activity, improving their ability to withstand environmental stresses; excessive or inappropriate NMs may cause oxidative stress, affecting plant growth and development. Copper nanoparticles, in particular, exhibit this dual nature, being beneficial at low concentrations but potentially harmful at high concentrations. This study provides a theoretical basis for the future development of nanofertilizers aimed at precisely targeting Gramineae plants to enhance their antioxidant stress capacity and improve photosynthesis efficiency. We emphasize the importance of balancing the agricultural advantages of nanotechnology with environmental safety in practical applications. Future research should focus on a deeper understanding of the interaction mechanisms between more NMs and plants and explore strategies to reduce potential environmental impacts to ensure the health and sustainability of the ecosystem while enhancing the yield and quality of Gramineae crops.
... In the environment, the released nanoparticles are affected by environmental agents such as light, oxidants and microorganisms. This can result in chemical or biological alterations and may lead to the release of nanoparticles (Nowack and Bucheli 2007). The surface of pristine nanoparticles can also be modified by environmental factors such as coating by organic materials or functionalization by chemical or biological processes. ...
... In the environment, the released nanoparticles are affected by environmental agents such as light, oxidants and microorganisms. This can result in chemical or biological alterations and may lead to the release of nanoparticles (Nowack and Bucheli 2007). The surface of pristine nanoparticles can also be modified by environmental factors such as coating by organic materials or functionalization by chemical or biological processes. ...
Increasing the production and usage of nanomaterials has increased the probability of exposure to these materials. Among the possible exposure scenarios (environmental, occupational, and domestic), workplaces where nanomaterials are produced, processed, used, and disposed of may pose certain health and safety challenges. Various field surveys have shown that workers who handle nanomaterials experience significant respiratory and dermal exposures. Exposure usually starts from the work environment, and then spreads to the exposed workers or employees. So far, many studies have pointed out the effects of nanomaterials on humans and the environment and have described them as harmful. On the other hand, some studies show that the toxicological behavior of nanomaterials is still less known, and this issue has raised concerns regarding these materials. This chapter discusses the health, safety and environmental hazards of nanomaterials, exposure scenarios, routes of human exposure to nanomaterials, their toxic effects, and current activities related to the reduction and control of exposure to these materials.
... Depending on their type, nanoparticles may be released into the atmosphere as aerosols, into the soil and surface water. Nanoparticles can be released as bare particles, functionalized particles, aggregates, or embedded in a matrix (Nowack & Bucheli, 2007). They can pose ecotoxicological hazards, undergo biodegradation, or bioaccumulate in the food chain (Scenihr, 2006;Rajalakshmi & Paari, 2023). ...
Nanomaterials are nowadays very common in our daily used products. The most prevalent nanoparticles that we encounter are silver nanoparticles. Almost all electronic appliances, including mobile phones, contain a certain amount of silver nanoparticles. Due to the unmanaged and unforeseen disposal of products containing nanomaterials over the years, silver nanoparticles have become almost omnipresent in the environment in different forms and concentrations. Research has shown that silver nanoparticles, in their lower size range with higher concentration and longer exposure time, can cause severe toxic effects on the plant cell cycle, growth, and development. Therefore, to restrict the encroachment of nanoparticle-containing waste or nano-waste into the environment, there should be a specialized management system that can assess, categorize, and formulate suitable strategies for the safe disposal of those nanowastes.
... Due to its non-absorbent nature in the human body and superior sunscreen efficacy compared to ZnO particles (Cross et al., 2007;Schulz et al., 2002;Smijs and Pavel, 2011), nano-TiO2 is increasingly incorporated into sunscreens to mitigate the adverse effects of both UVB (290-320 nm) and UVA (320-400 nm) radiation (Burnett and Wang, 2011). After being utilized by individuals, nano-TiO2 enters surface water either directly or indirectly through various pathways, coming into contact with algae, fish, aquatic plants, and zoobenthos, exerting toxic effects on them (Nowack and Bucheli, 2007). Relevant studies have shown that, the toxicity of nano-TiO2 varies based on different crystal properties, aquatic environment conditions and biological species (Li et al., 2022). ...
... Adsorption capacity of nanoparticles can indirectly help in bioremediation processes. When PAHs are adsorbed by the nanoparticles, the toxic effects of PAHs get reduced, which allows the microbes to grow even in high concentrations of the PAHs (Nowack and Bucheli 2007). According to reports by Gotovac et al. 2006;Yang et al. 2006, CNTs can adsorb PAHs. ...
With the constant progress of science and technology and the consequent rise in living standards, accumulation of anthropogenic wastes and toxic materials is increasing day by day. This is a major ecological hazard which calls for implementation of sustainable and efficient remediation strategies. Bioremediation is a popular remediation technique, but it is indeed disadvantageous in case of very high concentrations of toxic waste matter remediation treatments since such high concentrations can be harmful to the microorganisms themselves. In this regard, the integration of the new-age “nanotechnology” with the present approaches of bioremediation can be more successful in removal of hazardous materials. Nanomaterials possess unique physico-chemical properties which have been already employed in different areas of environmental sciences. Several reports have suggested that application of nanomaterials which are non-harmful for microorganisms can boost the microbial activity on specific toxic materials. Thus, nano-biotechnology can be a potential tool to amplify the effectiveness and efficiency of the bioremediation approaches in the terms of both time and cost requirements. The present chapter is focussed on the application of nano-biotechnology in bioremediation of industrial effluents, wastewater, etc. and, additionally, several nanomaterials which are efficient in removing toxic heavy metals have been discussed in detail.
... Metal oxides nanostructures have been considered for several potential applications in various fields, including nanodevices, nanoelectronics, optoelectronics, nanobiosensor or sensor, photochemical catalysis and gas sensor, etc. [1][2][3] Copper oxide (CuO) nanostructures are one of the very smart transition metal oxides among other metal oxides with small bandgap (∼2.4 eV), and at nanoscale having specific features as good electrochemical activity and stability in the solution. [4][5][6][7] Besides these characteristics, nanostructured CuO shows functional physical properties such as high surface-to-volume ratio, photochemical and thermal stability, high-temperature superconductivity, biocompatibility, less toxicity, etc. 8,9 These properties of CuO have also attracted the attention of biomedical research area and heavily used in glucose sensing, immuno-sensing, dopamine sensing, pharmaceutical activity, tumor therapy, and antifungal agent. 10,11 The U.S. Environmental Protection Agency (EPA) recognized CuO as an antimicrobial nanomaterial, after which, CuO received much more attention from the biomedical devices field for preventing bacterial infection. ...
Copper oxide nanorods (CuOnrs), capped with cetyltrimethylammonium bromide (CTAB-CuOnrs), and polyvinyl pyrrolidine (PVP-CuOnrs) were utilized to study the interaction of Aldicarb (A.D.) and Chlorpyrifos (C.P.) pesticides. Field-emission scanning electron microscopy and transmission electron microscopy studies confirmed the nanocrystalline structure of CuOnrs, CTAB-CuOnrs, and PVP-CuOnrs as having rod-like structures. The contact angle study showed the hydrophilic nature of the uncapped CuOnrs and PVP-CuOnrs with contact angle of 51° and 57°, respectively, while CTAB-CuOnrs exhibited hydrophobic nature with a contact angle of more than 90°. Interaction study of CuOnrs, CTAB-CuOnrs, and PVP-CuOnrs with A.D. and C.P was conducted using UV-Vis absorption study (in the 250 - 400 nm region). CuOnrs have shown the specific interaction with A.D., while CTAB-CuOnrs have shown with C.P. without using any bio-recognition elements. PVP-CuOnrs did not show systematic change with both pesticides confirming the capping agent-dependent specific interaction of the pesticides.
... Their use relies on features such as enhanced chemical reactivity resulting from the high surface-to-volume ratio [2,3]. Examples include industrial [4], medical [5,6], and environmental [7,8] applications. In addition, the combination of different nanomaterials, such as metallic nanoparticles and carbon nanostructures, makes it possible to produce new hybrid composites with interesting properties that combine the advantages of both [9]. ...
The use of nanoparticles (NPs) in industrial applications is consistently increasing given their peculiar properties compared to bulk precursor materials. As a result, there is a growing need to develop alternative technical strategies for the synthesis of such NPs using processes that are not only environmentally friendly but also easy and inexpensive to implement on an industrial scale. In this regard, a novel approach has recently been proposed for the safe and sustainable production of metal NPs directly from a bulky solid by magnetically driven low-energy wet milling, which overcomes the limits of applicability to ferromagnetic materials through a unique device configuration. In the present contribution, the understanding of this alternative configuration is deepened by computational investigation. Discrete Element Method (DEM) simulations were used to model the dynamics of the system, highlighting the role of the various parameters involved in the setup and operation of the process. The collisions between grinding and primary particles are analyzed in terms of frequency, impact angle, and energy. Comparing the results with the standard device configuration, the general trend is preserved, though collisions at higher impact angle and energy are also detected.
... The nanometer-scale structure of aluminum (Al) nanoparticles (nAl) causes these particles to have properties which can differ substantially from those observed in larger-sized samples. 1 These properties, useful in energetics applications, include more rapid reaction kinetics 2 leading to potentially higher reaction energies and flame temperatures, which in turn lead to density and impulse performance gains, and suppressed combustion instability. 3,4 These favorable impacts on material properties and performance, in addition to the low cost and abundance of Al, have caused great interest in nAl relevant research and developments. ...
... Once released, ENPs can reach the environmental compartments of water, soil, and air and may undergo a wide variety of physicochemical transformations (e.g., homo-and hetero-aggregation/agglomeration, formation of organic corona, dissolution, sulfidation or other transformations) (Garner and Keller, 2014;Gregory et al., 2012b;Zhou et al., 2012;Wang et al., 2015;Nowack and Bucheli, 2007;Praetorius et al., 2020a;Tomak et al., 2022;Hadjidemetriou and Kostarelos, 2017;Quik et al., 2014). It has been also shown that even before reaching the environment, many ENP have undergone significant transformation, either during product use or withing technical compartments such as WWTP (Mitrano et al., 2015). ...
There have been major advances in the science to predict the likely environmental concentrations of nanomaterials, which is a key component of exposure and subsequent risk assessment. Considerable progress has been since the first Material Flow Analyses (MFAs) in 2008, which were based on very limited information to more refined current tools that take into account engineered nanoparticle (ENP) size distribution, form, dynamic release, and better-informed release factors. These MFAs provide input for all environmental fate models (EFMs), that generate estimates of mass flows and concentrations in various environmental compartments. While MFA models provide valuable information on the magnitude of ENPs release, they do not account for fate processes, such as homo- and heteroaggregation, transformations, dissolution, or corona formation. EFMs account for these processes in differing degrees. EFMs can be divided into multimedia compartment models (e.g., atmosphere, waterbodies and their sediments, soils in various landuses), of which there are currently a handful with varying degrees of complexity and process representation, and watershed models which focus on the water and sediment compartments. Multimedia models have particular applications for considering predicted environmental concentrations (PECs) in particular regions, or for developing generic “fate factors” (i.e., overall persistence in a given compartment) for life-cycle assessment. Watershed models can track transport and eventual fate of emissions into a flowing river, from multiple sources along the waterway course, providing spatially and temporally resolved PECs. Both types of EFMs can be run with either continuous sources of emissions and environmental conditions, or with dynamic (e.g., temporally varying for example as a new nanomaterial is introduced to the market, or with seasonal applications), to better understand the situations that may lead to peak PECs that are more likely to result in exceedance of a toxicological threshold. In addition, bioaccumulation models have been developed to predict the internal concentrations that may accumulate in exposed organisms, based on the PECs from EFMs. The main challenge for MFA and EFMs is a full validation against observed data. To date there have been no field studies that can provide the kind of dataset(s) needed for a true validation of the PECs. While EFMs have been evaluated against a few observations in a small number of locations, with results that indicate they are in the right order of magnitude, there is a great need for field work. Another major challenge is the input data for the MFAs, which depend on market data to estimate the production of ENPs. The current information has major gaps and large uncertainties. There is also a lack of robust analytical techniques for quantifying ENP properties in complex matrices; machine learning may be able to fill this gap. Nevertheless, there has been major progress in the tools for generating PECs. With the emergence of nano- and microplastics as a leading environmental concern, some EFMs have been adapted to these materials. However, caution is needed, since most nano- and microplastics are not engineered, therefore their characteristics are difficult to generalize, and there are new fate and transport processes to consider.
Environmental pollution refers to the contamination of air, water, or soil with harmful substances, resulting in adverse effects on the ecosystems and human health. It is a significant global issue with severe consequences for the planet. One effective approach to combat environmental pollution is through bioremediation. Bioremediation is the use of organisms, such as bacteria, fungi, and plants, to break down or remove contaminants from a polluted environment. It is an environmentally friendly and cost-effective method that harnesses the power of nature to restore the ecosystem. Bioremediation using nanoparticles is a promising approach for the clean-up of environmental contaminants. This method combines the use of nanoparticles and natural remediation processes to enhance the degradation or immobilization of pollutants. It is important to note that the effectiveness of nanoparticles in achieving sustainable bioremediation depends on various factors, including the type of contaminant, environmental conditions, concentration of nanoparticles, and the specific nanoparticles chosen. This chapter focuses on the principles of utilizing nanoparticles to achieve sustainable bioremediation. It provides an insight into the processes and mechanism involved in the application of nanotechnology for sustainable bioremediation. Furthermore, we highlighted the potential ecological risks associated with the use of nanoparticles for bioremediation.
Microwave-assisted extraction (MAE) treatments seem to be a promising sample preparation strategy to isolate nanomaterials (NMs) from environmental samples prior to single particle inductively coupled plasma mass (spICP-MS) determination.
Introduction: The rapid development of nanotechnologies with their widespread prosperities has advanced concerns regarding potential health hazards of the Nanoparticles. Results: Nanoparticles are currently present in several consumer products, including medications, food, textiles, sports equipment, and electrical components. Despite the advantages of Nanoparticles, their potential toxicity has negative impact on human health, particularly on reproductive health. Conclusions: The impact of various NPs on reproductive system function is yet to be determined. Additional research is required to study the potential toxicity of various Nanoparticles on reproductive health. The primary objective of this review is to unravel the toxic effects of different Nanoparticles on the human reproductive functions and recent investigations on the reproductive toxicity of Nanoparticles both in vitro and in vivo.
The occurrence of different forms of iron and manganese colloids in the subsurface environment have been widely reported. However, their sedimentation kinetics and stability mechanisms are scarcely addressed. In this...
Agricultural applications of nanotechnologies necessitate addressing safety concerns associated with nanopesticides, yet research has not adequately elucidated potential environmental risks between nanopesticides and their conventional counterparts. To address this gap, we investigated the risk of nanopesticides by comparing the ecotoxicity of nanoencapsulated imidacloprid (nano-IMI) with its active ingredient to nontarget freshwater organisms (embryonic Danio rerio, Daphnia magna, and Chironomus kiinensis). Nano-IMI elicited approximately 5 times higher toxicity than IMI to zebrafish embryos with and without chorion, while no significant difference was observed between the two invertebrates. Toxicokinetics further explained the differential toxicity patterns of the two IMI analogues. One-compartmental two-phase toxicokinetic modeling showed that nano-IMI exhibited significantly slower elimination and subsequently higher bioaccumulation potential than IMI in zebrafish embryos (dechorinated), while no disparity in toxicokinetics was observed between nano-IMI and IMI in D. magna and C. kiinensis. A two-compartmental toxicokinetic model successfully simulated the slow elimination of IMI from C. kiinensis and confirmed that both analogues of IMI reached toxicologically relevant targets at similar levels. Although nanopesticides exhibit comparable or elevated toxicity, future work is of utmost importance to properly understand the life cycle risks from production to end-of-life exposures, which helps establish optimal management measures before their widespread applications.
Given the widespread use of mercuric oxide NPs (HgO-NPs), they have become increasingly prevalent in the soil ecosystem. Consequently, it is important to promptly evaluate their phytotoxic impacts. To this end, we have investigated the effects of HgO-NPs (0-200 mg/L) on germination and early growth of maize. Moreover, we have evaluated the interactive influences of HgO-NPs toxicity on the elongation and anatomical structures of primary roots. Relative to control, HgO-NPs decreased the germination percentage, speed and rate, but increased the mean germination time, mean daily germination time and time to 50% germination. The length and biomass of root and shoot and seedling vigour indices have significantly deteriorated. The inhibitory impacts of HgO-NPs on growth parameters were more pronounced in root than in shoot. The response of root was concomitant with dose and time-dependent inhibitions in root elongation and significant drops in root diameter, stele size, cortex size, and cortical cells count. The consequences of HgO-NPs were dose-dependent. For instance, the decrease of maize germination, growth, root elongation, and anatomy were more evident at 200 mg/L HgO-NPs compared to other doses and control. Overall, this study suggests that the presence of HgO-NPs leads to phytotoxic effects on germination and growth of young seedlings, highlighting a noteworthy challenge and environmental concern.
This chapter attempts to understudy the extent of nanoparticle transfer within the food chains, as well as factors determining trophic transfer, bioaccumulation, distribution, and toxic effects on predators. With the creation of several NPs, nanotechnology has gained popularity and provided the agriculture business with new tools. The specific benefits and drawbacks of using NPs need to be better understood, and this knowledge and understanding must be increased immediately. Significant levels of produced NPs have been introduced into the agro-environment due to the development of nanotechnologies. Although this technique has several advantages, researchers and industry professionals are concerned about the harmful disposal of different NPs in significant quantities (a few hundred tons annually). It appears that utilizing nanoagrochemicals is essential for advancing contemporary agriculture. The fundamental trophic level in the environment is represented by plants, which are also the primary producers and the main component of the food chain. However, the food chain may be impacted by the plants’ overtime contact with NPs and bioaccumulation of those NPs. Understanding trophic transfer potential and biomagnification of nanoparticles is imperative in order to thoroughly evaluate environmental risks linked with these nanoparticles and by extension nanomaterials.
Risk assessment and management in the realm of nanotoxicology represents an indispensable and multifaceted discipline that is profoundly committed to comprehending and mitigating the potential perils inherently associated with nanoparticles. Nanotoxicology, as a central component of this field, delves into the systematic exploration of the detrimental effects that nanoparticles can impose upon both living organisms and the delicate environment. It is thus imperative to meticulously scrutinize and evaluate the multifarious risks posed by nanoparticles. It is a nonnegotiable imperative that these risks are subjected to thorough analysis and subsequently managed with a suite of highly effective strategies, all oriented toward preserving human health and the ecological equilibrium. The armamentarium of these strategic approaches encompasses a diverse array of tools, including the formidable instrument of regulatory oversight. This not only serves as a sentinel guarding against potential hazards but also lays down the law when it comes to the utilization of nanoparticles, making sure that it is consistent with safety and environmental preservation. Research and development emerge as another cornerstone in this protective agenda. This involves a rigorous and relentless pursuit of knowledge, where the toxicological aspects of nanoparticles are painstakingly scrutinized and safer alternatives are earnestly sought. Furthermore, workplace safety protocols stand as a bulwark against potential perils. These protocols codify the correct methods for handling, storing, and disposing of nanomaterials, taking into account critical elements such as engineering controls, personal protective equipment, and comprehensive worker training. Consumer safety requires proper labeling and transparent disclosure of nanoparticle usage that are critical components of this approach, for they enable consumers to make informed choices and therefore reduce potential health risks. The mitigation of long-term hazards associated with nanoparticle waste is coupled with measures to prevent unintended releases into the environment. An equally potent strategy involves collaborative research and information sharing, where the combined efforts of scientists, regulatory authorities, and industries are harnessed to collectively assess risks, identify best practices, and forge comprehensive safety guidelines. This harmonious collaboration fosters transparency, shaping the responsible nanoparticle use while facilitating early hazard identification, risk mitigation, and informed decision-making, all of which are instrumental in shielding public health and the environment from potential harm. The aim of the chapter is to present the secure and responsible deployment strategies of nanoparticles while diligently minimizing their potential adverse impacts on society and the environment. The report represents a vanguard of vigilance, ensuring that the vast potential of nanotechnology is harnessed without jeopardizing the well-being of humanity or the ecological balance of ecosystems.
Initially, basic equations are given to express the activity concentrations and concentrations of potential α-energies of radon (222Rn) and thoron (220Tn) and their short-lived products in indoor air. The appearance of short-lived products as a radioactive aerosol is shown, and the fraction of the unattached products is particularly exposed, a key datum in radon dosimetry. This fundamental part is followed by giving the sources of radon and thoron indoors, and thus, their products, and displaying the dependence of their levels on the ground characteristics, building material and practice, and living–working habits of residents. Substantial hourly, daily, and seasonal changes in their activity concentrations are reviewed, as influenced by meteorological parameters (air temperature, pressure, humidity, and wind speed) and human activity (either by ventilation, air conditioning and air filtration, or by generating aerosol particles). The role of the aerosol particle concentration and their size distribution in the dynamics of radon products in indoor air has been elucidated, focusing on the fraction of unattached products. Intensifying combined monitoring of radon short-lived products and background aerosol would improve radon dosimetry approaches in field and laboratory experiments. A profound knowledge of the influence of meteorological parameters and human activities on the dynamics of the behaviour of radon and thoron accompanied by their products in the air is a prerequisite to managing sustainable indoor air quality and human health.
The rapid inclusion of zinc oxide nanoparticles (ZnO NPs) in nanotechnology-based products over the last decade has generated a new threat in the apprehension of the environment. The massive use of zinc nanosized products will certainly be disposed of and be released, eventually entering the aquatic ecosystem, posing severe environmental hazards. Moreover, nanosized ZnO particles owing the larger surface area per volume exhibit different chemical interactions within the aquatic ecosystem. They undergo diverse potential transformations because of their unique physiochemical properties and the feature of receiving medium. Therefore, assessment of their impact is critical not only for scavenging the present situation but also for preventing unintended environmental hazards. Algae being a primary producer of the aquatic ecosystem help assess the risk of massive NPs usage in environmental health. Because of their nutritional needs and position at the base of aquatic food webs, algal indicators exhibit relatively unique information concerning ecosystem conditions. Moreover, algae are presently the most vital part of the circular economy. Hence, it is imperative to understand the physiologic, metabolic, and morphologic changes brought by the ZnO NPs to the algal cells along with the development of the mechanism imparting toxicity mechanism. We also need to develop an appropriate scientific strategy in the innovation process to restrain the exposure of NPs at safer levels. This review provides the details of ZnO NP interaction with algae. Moreover, their impact, mechanism, and factors affecting toxicity to the algae are discussed.
Nanoplastics (NPs) are usually formed by the decomposition of large plastics, which will cause water pollution after entering the water body. Carbon filter column is used to adsorb and remove polystyrene nanoparticles (PSNPs). The influence of experimental conditions on adsorption was investigated and fitted by kinetic model. The results show that increasing the height of carbon filter column and decreasing the initial concentration of PSNPs and water flow rate can prolong the breakthrough time of carbon filter column. When the initial concentration of PSNPs is 0.8 mg L-1, the influent flow rate is 4 mL min-1 and the height of carbon filter bed is 8.5 cm, the removal effect is the best, and the depletion point of carbon filter column is extended to 48 h. Adams-Bohart model is suitable for describing the initial stage of adsorption. Thomas and Yoon-Nelson models can well describe the whole dynamic adsorption process of PSNPs, and Yoon-Nelson model can accurately predict the time required for 50% PSNPs to penetrate the carbon column. The adsorption mechanism of NPs by carbon filter column is mainly through the attachment sites and pore retention provided by particles on the surface of activated carbon. This study can provide new technical and theoretical support for the removal of NPs.
Current sample preparation strategies for nanomaterials (NMs) analysis in soils by means single particle inductively coupled plasma mass spectrometry have significant constrains in terms of accuracy, sample throughput and applicability (i.e., type of NMs and soils). In this work, strengths and weakness of microwave assisted extraction (MAE) for NMs characterization in soils were systematically investigated. To this end, different extractants were tested (ultrapure water; NaOH, NH4OH, sodium citrate and tetrasodium pyrophosphate) and MAE operating conditions were optimized by means of design of experiments. Next, the developed method was applied to different type of metallic(oid) nanoparticles (Se-, Ag-, Pt- and AuNPs) and soils (alkaline, acid, sandy, clayey, SL36, loam ERMCC141; sludge amended ERM483). Results show that Pt- and AuNPs are preserved and quantitatively extracted from soils in 6 min (12 cycles of 30 s each) inside an 800 W oven by using 20 mL of 0.1 M NaOH solution. This methodology is applicable to soils showing a wide range of physicochemical properties except for clay rich samples. If clay soil fraction is significant (>15%), NMs are efficiently retained in the soil thus giving rise to poor recoveries (<10%). Labile NMs such as Se- and AgNPs could not be analyzed by means this approach since extraction conditions favors dissolution. Finally, when compared to current extraction methodologies (e.g., ultrasound, cloud point extraction, etc.), MAE affords better or equivalent accuracies and precision as well as higher sample throughput due to treatment speed and the possibility to work with several samples simultaneously.
Terrestrial ecosystems are increasingly being exposed to metallic nanoparticles (MNPs). However, the global‐scale impact of MNPs on soil carbon dioxide (CO 2 ) emission remains unknown, limiting our understanding of the role of MNPs in global carbon cycle. We compiled a dataset comprising 1764 pairs of experimental observations to investigate the effects of MNPs exposure on soil respiration parameters, including respiration rates, related enzyme activities, and microbial variables. We found that MNPs could stimulate or suppress soil basal respiration rates across global environments, depending largely on the type of MNPs. We further showed that, although the inhibition of MNPs on most enzyme activities peaked in short‐term exposure (≤28 days), prolonged exposure to MNPs still inhibited soil organic carbon degradation. Finally, we determined that environmental conditions (e.g., soil pH and presence/absence of plants) were also important regulators of the influence of MNPs on soil respiration parameters. Our findings underline that the effects of MNPs on soil CO 2 emission depended on MNPs type, exposure design, and environmental factors, which is critical for predicting the role of MNPs in influencing the global carbon cycle and climate change.
The growing population is driving up the demand for food, but the inadequate efficiency of traditional fertilizers is constraining crop production. Nanotechnology-based fertilizers represent a novel strategy for boosting agricultural output and show great potential as viable options in the fertilizer industry, as they can significantly enhance nutrient retention and promote optimal growth. Very recently, slow and controlled release nanofertilizers have evolved through the development of nanocomposites or coating techniques with the aid of various chemical entities. These types of slow release nanofertilizers are more effective than normal nanofertilizers as these fertilizers deliver nutrients in a controlled manner and can be regulated by various environmental and physical stimuli (pH, temperature, humidity, etc.). Their nutrient use efficiency (NUE) is also far better than the normal nanoparticles (individual nanoparticles like iron, zinc, copper nanoparticles etc.), as these nanocomposites demonstrate zero or very little nutrient leaching. Utilizing controlled release fertilizers mitigates nutrient loss from volatilization and leaching and offers a meticulously tailored nutrient release system harmonizing with the objective of sustainable agriculture. Therefore, this review article provides insights into slow and controlled release nanofertilizers, including preparation approaches, nutrient-release techniques, analytical detection methods, current status, role in crop improvement, commercial viability, and future perspectives.
Stable homogeneous dispersions of carbon nanotubes (CNTs) have been prepared by using sodium dodecyl sulfate (SDS) as dispersing agent. To our knowledge, it is the first report to quantitatively characterize colloidal stability of the dispersions by UV-vis spectrophometric measurements. When the sediment time reaches 500 h, the supernatant CNT concentration drops as much as 50% for the bare CNT suspension, compared to 15% with the addition of SDS. Furthermore, after 150 h, no precipitation is found for CNT/SDS dispersions, exhibiting an extreme stability. Zeta potential, auger electron microscopy, and FTIR analysis are employed to investigate the adsorption mechanism in detail. It has been concluded that the surfactant containing a single straight-chain hydrophobic segment and a terminal hydrophilic segment can modify the CNTs-suspending medium interface and prevent aggregation over long periods. The morphology of the CNT dispersions is observed with optical microscopy. An intermediate domain of homogeneously dispersed nanotubes exhibits an optimum at 0.5 wt% CNTs and 2.0 wt% SDS.
Nanoparticles are discrete nanometer (10−9 m)-scale assemblies of atoms. Thus, they have dimensions between those characteristic of ions (10−10 m) and those of macroscopic materials. They are interesting because the number of atoms in the particles is small enough, and a large enough fraction of them are at, or near surfaces, to significantly modify the particle’s atomic, electronic, and magnetic structures, physical and chemical properties, and reactivity relative to the bulk material. Nanoparticle surfaces themselves may be distinctive. Particles may be terminated by atomic planes or clusters that are not common, or not found, at surfaces of the bulk mineral. These, and other size-related effects will lead to modified phase stability and changes in reaction kinetics.
What makes a nanoparticle a nanoparticle? Definitions of the size ranges for molecules, nanoparticles, and macroscopic solids must be compound specific. However, a useful upper limit for nanoparticles is the size at which one of its properties deviates from the value for the equivalent bulk material by an amount that is significantly larger than the error of the method used to make the measurement (a few percent). In practice, some characteristic will probably be different enough to warrant description as a “nanoparticle” if it is less than a few tens of nanometers in diameter, and perhaps less than a fraction of a micron in diameter.
Because of the importance of size-dependent property changes to the materials sciences, size-property relationships have been studied in detail for some systems. For example, for semiconductors, size effects become important when the particle diameter is close to the Bohr diameter of excitons in the bulk phase. Generally, semiconductor size quantization effects (relevant for naturally occurring metal sulfides, for example) appear when particles are less than 10 nm in diameter (Vogel and Urban 1997).
Definition of the …
A water-soluble complex of C60 is formed on refluxing a solution of gamma-cyclodextrin with solid C60; the lifetime of the triplet excited state of C60 in the complex is 83-mu-s in an oxygen free solution.
Typical polycyclic aromatic hydrocarbon mixtures are established lung carcinogens, but the quantitative exposure-response relationship is less clear. To clarify this relationship we conducted a review and meta-analysis of published reports of occupational epidemiologic studies. Thirty-nine cohorts were included. The average estimated unit relative risk (URR) at 100 mug/m(3) years benzo[a]pyrene was 1.20 [95% confidence interval (CI), 1.11-1.29] and was nor sensitive to particular studies or analytic methods. However, the URR varied by industry. The estimated means in coke ovens, gasworks, and aluminum production works were similar (1.15-1.17). Average URRs in other industries were higher but imprecisely estimated, with those for asphalt (17.5; CI, 4.21-72.78) and chimney sweeps (16.2; Cl, 1.64-160.7) significantly higher than the three above. There was no statistically significant variation of URRs within industry or in relation to study design (including whether adjusted for smoking), or source of exposure information. Limited information on total dust exposure did not suggest that dust exposure was an important confounder or modified the effect. These results provide a more secure basis for risk assessment than was previously available.
Environmental Context. The fate and behaviour of trace pollutants are very strongly modified, and usually dominated, by their physical and chemical interactions with naturally occurring aquatic colloids (defined as solid phase material with one dimension between 1 nm and 1 μm). This review summarises the area and key advances in the field of natural aquatic colloids, including technique development and quantification of colloidal structure and interactions with pollutants. The review also discusses areas in which significant advances are likely to be made or are needed and, as such, provides a framework for further work in the next few years.
Abstract. Natural aquatic colloids are materials with one dimension between 1 nm and 1 μm. More informally defined, nanoparticles are materials with at least one dimension less than 100 nm. Both colloids and nanoparticles have significant effects on pollutant, nutrient, and pathogen chemistry, transport and bioavailability, and may themselves be bioavailable. Techniques for their fractionation, characterization and analysis have improved greatly in recent years. Although knowledge of their structure and environmental impact has also increased, it has not done so to the same degree and thus the field awaits the substantial application of new methodologies. This paper reviews the current state of the art in this area and also discusses likely future developments.
Formation of highly condensed black carbon (BC) from vegetation fires and wood fuel combustion presumably transfers otherwise rapidly cycling carbon from the atmosphere-biosphere cycle into a much slower cycling geological form. Recently reported BC fractions of total organic carbon (TOC) in surficial marine sediments span a wide range (2-90%), leaving it presently unclear whether this variation reflects natural processes or is largely due to method differences. In order to elucidate the importance of BC to carbon burial the specificity of applied methods needs to be constrained. Here the operating range and applicability of a commonly used chemothermal oxidation (CTO) method is evaluated using putative BC standards, potentially interfering substances, and natural matrix standards. Test results confirm the applicability of the method to marine sediments. Integrity tests with model substrates suggest applicability to low-carbon soils but only with a lower specificity to seawater particulate matter. The BC content of marine sediment samples in a set of studies employing the CTO method proved to be consistent with associated geochemical information. The radiocarbon content of the BC isolate in an environmental matrix standard was shown to be similar to the radiocarbon signature of pyrogenic polycyclic aromatic hydrocarbons (PAHs), here serving as molecular markers of combustion (fraction modern fM of BC was 0.065+/-0.014 and of PAHs 0.056+/-0.020), while being clearly distinct from the radiocarbon content of the bulk TOC (fM=0.61+/-0.08). Urgent questions such as the global accumulation rate of black carbon in soils and sediments may prove approachable with the chemothermal oxidation technique of BC quantification.
Zero-valent iron nanoparticle technology is becoming an increasingly popular choice for treatment of hazardous and toxic wastes, and for remediation of contaminated sites. In the U.S. alone, more than 20 projects have been completed since 2001. More are planned or ongoing in North America, Europe, and Asia. The diminutive size of the iron nanoparticles helps to foster effective subsurface dispersion whereas their large specific surface area corresponds to enhanced reactivity for rapid contaminant transformation. Recent innovations in nanoparticle synthesis and production have resulted in substantial cost reductions and increased availability of nanoscale zero-valent iron (nZVI) for large scale applications. In this work, methods of nZVI synthesis and characterization are highlighted. Applications of nZVI for treatment of both organic and inorganic contaminants are reviewed. Key issues related to field applications such as fate/transport and potential environmental impact are also explored.
In order to characterize hybrid bio/abio technology utilizing carbon nanotubes (CNTs), in situ, real-time, yet noninvasive methods of accurate and reliable imaging are needed for observing CNTs' interactions with biological materials, i.e., DNA, in biologically relevant aqueous environments. Optical visualization and characterization of individual CNTs in aqueous solutions were explored in this study using 1-pyrenebutanoic acid, succinimidyl ester (PSE) and a conventional fluorescence microscope. The results demonstrate the potential of fluorescence microscopy based on PSE-based staining methodology monitoring with nanometer resolution of individual CNTs and their manipulation with biological materials in bio/abio hybrid systems.
Common-or-garden starch can render single-walled carbon nanotubes (SWNTs) readily soluble in water. The secret is to preorganize the linear amylose component in the starch into a helix with iodine prior to bringing the SWNTs on the scene. The SWNTs displace the iodine molecules in a “pea-shooting” type of mechanism (see scheme). After some physical cajoling of the aqueous solution containing the starch–SWNT complex, a fine “bucky paper” is formed. Spitting in the aqueous solution, followed by sitting around for a few hours, also enables equally fine “bucky paper” to be harvested.
The effects of nano-TiO2 (rutile) and non-nano-TiO2 on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25–4‰ nano-TiO2 treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5‰ nano-TiO2.
The effects of non-nano-TiO2 are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO2 improves the growth of spinach seeds still needs further study.
Various types and structures of synthesized non-carbon nanotubes (N-NT) based on carbonitrides BxCyNz, boron nitride BN, sulfides WS2, MoS2, selenides NbSe2, halides NiCl2, transition metal oxides SiO2, TiO2, MoO3, V2O5 are considered, as well as theoretically predicted N-NT based on P, Si, Ge, and III-V semiconductors. General criteria for the stability of non-carbon nanotubes are analyzed.
A TEM Analysis of Particulates in a Polar Ice Core - Volume 9 Issue S02 - E. V. Esquivel, L E. Murr
Micelle-like Amphiphilic nano-sized polyurethane (APU) particles synthesized based on amphiphilic urethane acrylate nonionomers could solubilize phenanthrene within their hydrophobic interiors as the same way that surfactant micelles do in aqueous phase. At low concentration of APU or Triton X-100 (Below CMC of Triton X-100), APU aqueous pseudophase exhibited greater reduction of phenanthrene sorption on aquifer sand and higher extraction efficiency of sorbed phenanthrene than Triton X-100 aqueous pseudophase. At higher APU particle and Triton X-100 dose in aqueous solution, the extraction efficiency of APU aqueous solution is almost same as that of Triton X-100 aqueous solution, even though APU particles exhibited low solubilizing efficiency than Triton X-100 micelles in absence of aquifer soil. That's because APU particles have relatively low degree of sorption on aquifer sand, due to their chemically crosslinked structure. APU particles could be also recovered 100% through ultrafiltration process at greater pore size of separation membrane, which will make soil-washing process using APU particles more economical and useful in practical applications.
This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.
Colloids (diameter typically < ca. 1 μm) are present in all aquatic systems. They have a high surface to mass ratio and therefore a large sorption capacity for both pollutants and microbial water impurities. Also, microorganisms as such can be regarded as colloidal matter. For drinking water purification it is vitally important to effectively remove such particulate water contents. The laser-induced breakdown detection (LIBD) was used as a powerful tool for the quantification of aquatic nano-particles in very low concentrations, The Fe(III)-assisted filtration used for purification of water rom Lake Constance did not only remove suspended particles, but also colloids with a mean efficiency higher than 98% (regarding the mass concentration). The number weighted mean particle diameter before filtration was typically several hundred nanometers, after filtration it was reduced to an average of 54 nm. The average mass concentration before the filtration step was 57 μg/L, afterwards only 0.66 μg/L. In a separate experiment it could be shown that the LIBD technique is capable of detecting microorganisms in water.
This article shows that the introduction of the Surface Complexation model into the »family« of theories that comprise the Theory of Colloid Stability makes that theory »absolute«. This means that one characterizes the electrical interfacial layer, e.g. by adsorption measurements, and calculates the equilibrium parameters, such as the equilibrium constants of protonation and deprotonation of amphoteric surface OH groups, equilibrium constants of the association of counterions, capacitances of inner and outer interfacial layers and the total concentration of surface sites. From these equilibrium parameters one evaluates the potential at the onset of the diffuse layer (φd) and calculates the electrostatic interaction energy yielding the rate constant of aggregation and the stability coefficient. It is shown that counterion association plays an important role in the aggregation phenomena by reducing the value of potential φd.
Nano terminology became trendy, popular and representative of all that is high-tech in the materials world. Within the past two decades, a variety of terms sharing the prefix nano, such as nanoparticle, nanomaterial, nanophase and nanostructured, has emerged to describe certain materials, technologies and even businesses. Although not yet a household word, it is indeed well-known within and increasingly vital to the advanced materials community and high-technology business sector.
The spatial distributions of polycyclic aromatic hydrocarbons (PAHs) in many aquatic environments appear to be dictated by partitioning with soot as opposed to with bulk organic matter. Recent field-observations of the solid-water distribution coefficients of members of this contaminant assemblage are consistently elevated compared to expectations from organic-matter-based partition models. Increasing hydrophobicity across the PAHassemblage is seen to affect relative distributions. Using PAHs as molecular markers of sorption suggests that an active exchange of such planar molecules between a strong sorbent, such as soot, and the surrounding water is taking place. Quantification of PAHs, organic carbon, and soot carbon in surficial continental shelf sediments off New England revealed that the distribution of PAHs was highly correlated with soot carbon. Estimates of the soot-water partition coefficient for several PAHs, assuming sorbate-soot association is thermodynamically similar to sorbate fusion, are found to agree reasonably well with published aqueous sorption constants to activated carbon.
The Permian-Triassic boundary (PTB) event, which occurred about 251.4 million years ago, is marked by the most severe mass
extinction in the geologic record. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly,
consistent with a catastrophic, possibly extraterrestrial, cause. Fullerenes (C60 to C200) from sediments at the PTB contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous
chondrites. These data imply that an impact event (asteroidal or cometary) accompanied the extinction, as was the case for
the Cretaceous-Tertiary extinction event about 65 million years ago.
The highly condensed products and residues of incomplete combustion of biomass and fossil fuel termed black carbon ( BC) partake in a multitude of important geochemical processes. However, ambiguity persists because different quantification methods give highly variable results, leaving it unclear whether this reflects method difficulties or that different methods simply mirror different parts of the BC spectrum. Introducing additional wet chemical ex situ pretreatment steps (Gelinas et al. 2001b), to a commonly applied chemothermal oxidation (CTO) method led to large handling and transfer losses of hydrophobic diesel-soot BC (NIST SRM-2975). The resulting yield of soot BC spiked to a coastal marine and a freshwater sediment was only 6 +/- 1% and 70 +/- 4%, respectively, for the entire ex situ procedure. Instead, a standard addition approach yielded statistically significant linear returns of incremental soot BC additions. The slopes suggested that 51 +/- 6% and 78 +/- 6% of the added soot BC was accounted for in the marine and freshwater sediment, respectively. The lower recovery of soot BC in the marine sediment is likely caused by chloride enhancing the contact between BC surfaces and mineral oxides, catalyzing the BC oxidation. A consequential lowering of the oxidation energy from 375 degreesC to 360 degreesC resulted in increased soot BC yields of 75 +/- 7% and 97 +/- 3% in the marine and freshwater sediments, respectively. The standard addition approach suggests a native "soot BC-like" concentration of 0.48 mg BC/g dry weight ( soot BC/total organic carbon = 0.03) in the bioturbated marine sediment from Kosterfjord, Skagerrak and 6.2 mg BC/g dry weight ( soot BC/TOC = 0.10) in the heavily polluted Rhine River sediment.
The interactions of common environmental contaminants with C60 have been studied to evaluate the environmental impact of carbon nanomaterials. The adsorption and desorption interaction of the hydrophobic contaminants naphthalene and 1,2-dichlorobenzene with C60 was characterized. Processes that cause the wetting and disaggregating of C60 particles also affect the extent of organic contaminant sorption to C60 aggregates by orders of magnitude. C60 dissolved in organic solvents such as toluene can form stable nanoscale aggregates upon vigorous mixing in water. These nanoscale C60 particles form stable suspensions in water and are referred to as ‘nano-C60’. Desorption of contaminants from stable suspensions of nano-C60 exhibits hysteresis. The experimentally observed adsorption/desorption hysteresis is described by a two-compartment desorption model: first, adsorption to the external surfaces that are in contact with water, and second, adsorption to the internal surfaces within the aggregates.
Literature is reviewed describing through soil colloid-facilitated transport of contaminants such as phosphorus, pesticides and other agrochemicals, plus a range of biological microorganisms. Smaller microorganism (viruses and bacteria) are transported mainly (like chemical contaminants) by adsorption onto otherwise harmless mobile colloidal clay particles or soil organic matter. Potential impediments to movement of colloids through soil can be subdivided into straining and filtration, depending on whether a particle has a dimension similar to pores (leading to physical trapping) or much smaller. Filtration mechanisms, including interception, diffusion and sedimentation, have been compared to those described in the extensive engineering literature on deep bed filtration. Sorption processes are discussed, both those to static components of the soil matrix and onto mobile colloids. The chemical influences of ionic strength and pH to colloid transport are reviewed, as well as the double diffusion layer as a mechanism linking particles to surfaces.Numerous reported studies using column experiments to measure colloid or contaminant transport through soil have been reviewed. Many indicate the importance of macropore flow which allows rapid unrestricted transport of contaminant carrying colloids. Some experiments determine a filtration coefficient for a simple filtration equation representing straining and filtration processes. The few existing models (incorporating this filtration equation), both for column experiments and for the field situation, are reviewed as background to further development of a field-scale model representing colloid-facilitated transport of a range of chemical and microbiological contaminants.
Dr. Murashov has emphasized the major objective of our paper, which shows that exposure of growing plant roots to nanoparticles of alumina may result in growth inhibition and that this effect appears to be related to surface characteristics of the particles. The paper indicates that the mechanism(s) by which the particles may induce growth inhibition needs further attention. We agree that it is premature to draw definitive conclusions about toxicity mechanisms.
It is demonstrated that high-performance liquid chromatography (HPLC) is an excellent and reliable analytical method for the determination of the C60 and C70 fullerenes extracted from geologic samples because the analysis is carried out at room temperature, is non-destructive (fullerenes can be recovered), and is easily calibrated with synthetic fullerenes. The determination of fullerenes in geologic materials is greatly empowered by the preseparation of fullerenes from organics on a “big” HPLC column.
Materials containing a spherical pi-electron moiety have the added advantage of enhanced intermolecular interactions. Buckminsterfullerene is a special spherical pi-electron carbon cluster which, unfortunately, is only sparingly soluble in most common solvents. It is therefore imperative that the cluster be derivatized (functionalized) to be incorporated into most familiar solids for materials science applications. Addition and cycloaddition reactions are the only synthetic methods available to functionalize C-60. Of these, the so called Bingel, Bingel-Hirsch, Prato and azoalkane cycloaddition reactions are the most useful and have been used over the past decade to produce a myriad Of C-60-based molecules as well as many materials. So far, there are only two areas where functionalized fullerenes have had an impact: plastic solar cells and optical limiting glasses, with lesser applications in polymeric materials and fullerene-modified traditional materials. The emphasis of this article is therefore on photodiodes and optical limiting glasses.
Colloidal phases in natural waters may be important in various environmental questions, especially those concerning the cycling of vital and toxic trace chemicals. Current treatments of the role of colloids in chemical speciation largely rely on operational definitions of phases such as 1,000-Da ultrafilter and 0.45-μm filter cut-offs. Defining chemical phases exclusively by a physical parameter such as size is contributing to a situation where the observed filterable vs. unfilterable distribution coefficients. D, are not well predicted from thermodynamically derived sorbed vs. solute equilibrium constants, K. Achieving the goal of relating the natural distributions of chemicals to theoretical expectations is contingent upon progress in development of a functionally meaningful colloid definition and interpretation of observed distributions of trace substances in terms of the relevant physicochemical properties of the system. We assess the phase status of typical components in natural waters from a 'chemcentric' point of view (i.e. one whose motivation is to understand the cycling of trace chemicals in the environment). As a result, we define colloids so as to provide a thermodynamic grounding for evaluating chemical speciation and a hydrodynamic framework distinguishing phases that are transported with the solution from those that are not. These constraints lead one to define an aquatic colloid as any constituent that provides a molecular milieu into and onto which chemicals can escape from the aqueous solution, and whose movement is not significantly affected by gravitational settling. Such a definition allows development of mass balance equations, suited to assessing chemical fates, that reflect processes uniquely acting on dissolved, colloidal, or settling particle phases.
The excitation of C60 incorporated in triton X-100 micelles has been studied by laser flash photolysis. Reductive quenching of triplet-excited 3C60 by diazabicyclooctane (DABCO) has been established in the micellar assembly, in aqueous solution of the fullerene embedded in γ-cyclodextrin, in alcohols and non-polar toluene. In aqueous media potassium hexacyanoferrate(II) and potassium iodide have been employed in the reductive quenching process as well. The C60− radical anion in all investigations has been characterized by its IR absorption. The formation and the half-life of C60− have been shown to be strongly dependent on the polarity of the environment. By utilizing DABCO as a quencher a half-life of 440 μs has been observed in the micellar assembly, while the respective values in propan-2-ol and butan-1-ol are 110 and 98 μs, respectively. In aqueous solution the radical anion γ-CD/C60− decays with a half-life of 59 μs and, in contrast, in the non-polar toluene no formation of any C60−. could be detected. The results are consistent with a charge-separated 3C60-quencher contact pair.
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Most undergraduate students of aqueous geochemistry are told that polynuclear aqueous complexes can largely be ignored because they form only from concentrated metal solutions that are rare at the Earth’s surface. However, these polynuclear complexes can serve as models for more-complicated surface structures and are the precursors to nanometric and colloidal solids and solutes. There are many reasons why polynuclear complexes should be foremost in the minds of geochemists, and particularly those geochemists who are interested in molecular information and reaction pathways:
1. Polynuclear complexes contain many of the structural features that are present at mineral surfaces, including a shell of structured water molecules. Because aqueous nanoclusters tumble rapidly in an aqueous solution, one can use solution NMR spectroscopy to determine the structure and the atomic dynamics in these clusters in ways that are impossible for mineral surfaces.
2. Some polynuclear complexes are metastable for long periods of time and may represent an important vector for the dispersal of metal contaminants from hazardous waste. The chemical conditions found in many polluted soils: high metal concentrations, elevated temperatures, and either highly acidic or highly alkaline solutions with a large pH-gradient, are needed to synthesize many polynuclear complexes. It is easy to make a solution that is 5 M in dissolved aluminum at 4 < pH < 6, composed of nanometer-sized clusters that are stable for months or years.
3. Polynuclear complexes lie at the core of many biomolecules, including metalloproteins such as ferritin and enzymes such as nitrogenase. Recent work has suggested that they are present in natural waters (e.g., Rozan et al. 2000) and serve as nuclei for crystal growth.
4. Aqueous clusters are sufficiently small that they can serve as experimental models for ab initio computer simulations that relate bonding to reactivity.
In this chapter we discuss polynuclear complexes of aluminum. There is …
Environmental context. Nanoparticulate materials are increasingly being used as catalysts and lubricants, for pollution control and drug delivery, and in electronics, fabrics, cosmetics and sunscreens. In spite of this growth, information about the fate and toxicity of nanoparticles in the environment is limited, partly due to the lack of techniques capable of measuring nanoparticles in complex environmental matrices. One emerging tool, flow field-flow fractionation, can be used to determine the presence and particle size distribution of engineered nanoparticles, for example in soil pore waters, thereby enhancing our understanding of their environmental fate and impacts.
Abstract. This paper reports preliminary results for the determination of engineered ZnO nanoparticles using flow field-flow fractionation (FlFFF). This separation technique was used to determine the particle size distributions (PSDs) of ZnO nanoparticles spiked in soil suspensions. Before FlFFF analysis, the soil was prepared in suspension form, shaken overnight and gravitationally settled to extract the <1-µm fraction. The effect of aging was also investigated using soil samples incubated with known concentrations of ZnO nanoparticles for 7 and 14 days. The results show that FlFFF can be used to determine the PSD of engineered nanoparticles and monitor their partitioning and stability in soil suspensions.
Fullerenes have been identified by high-performance liquid chromatography with UV-visible spectroscopic analysis of toluene extracts of deep sea claystones from Permo-Triassic (P/T) boundary sections in the Inuyama area, central Japan. The analysis reveals the presence of 10-20 parts per trillion of C60 only in the dark-colored rock samples, suggesting the anoxia at the time of the P/T boundary 250 million years ago, when the greatest Phanerozoic mass extinction occurred. The fullerenes were likely synthesized within locally anoxic zone in the extensive wildfires on the supercontinent Pangea and deposited on an anoxic deep-sea floor of the superocean Panthalassa.
Nanoparticles are important in natural environments due to their size, tunable properties and accessible surfaces and our control over these properties can be exploited to create or add value to a variety of technologies. Many consumer products that incorporate nanoparticles, such as sunscreens and clothing, are already in the marketplace, and the industry is growing fast. This book highlights also the many valuable environmental technologies that can come from the applications of unique nanomaterial properties. As this nascent technology area matures, the debate about the whether the unknown risks of nanomaterial use balances its established benefits will only intensify.
This review highlights the ubiquity of black carbon (BC) produced by
incomplete combustion of plant material and fossil fuels in peats,
soils, and lacustrine and marine sediments. We examine various
definitions and analytical approaches and seek to provide a common
language. BC represents a continuum from partly charred material to
graphite and soot particles, with no general agreement on clear-cut
boundaries. Formation of BC can occur in two fundamentally different
ways. Volatiles recondense to highly graphitized soot-BC, whereas the
solid residues form char-BC. Both forms of BC are relatively inert and
are distributed globally by water and wind via fluvial and atmospheric
transport. We summarize, chronologically, the ubiquity of BC in soils
and sediments since Devonian times, differentiating between BC from
vegetation fires and from fossil fuel combustion. BC has important
implications for various biological, geochemical and environmental
processes. As examples, BC may represent a significant sink in the
global carbon cycle, affect the Earth's radiative heat balance, be a
useful tracer for Earth's fire history, build up a significant fraction
of carbon buried in soils and sediments, and carry organic pollutants.
On land, BC seems to be abundant in dark-colored soils, affected by
frequent vegetation burning and fossil fuel combustion, thus probably
contributing to the highly stable aromatic components of soil organic
matter. We discuss challenges for future research. Despite the great
importance of BC, only limited progress has been made in calibrating
analytical techniques. Progress in the quantification of BC is likely to
come from systematic intercomparison using BCs from different sources
and in different natural matrices. BC identification could benefit from
isotopic and spectroscopic techniques applied at the bulk and molecular
levels. The key to estimating BC stocks in soils and sediments is an
understanding of the processes involved in BC degradation on a molecular
level. A promising approach would be the combination of short-term
laboratory experiments and long-term field trials.
The adsorption of lead to TiO2 materials with different particle sizes and compositions was investigated to examine the factors controlling metal adsorption to nanoparticles. Experiments were conducted with four different TiO2 materials. Three of the materials were nanoparticles, with sizes ranging from 20 to 33 nm, and the fourth was a bulk material with a 520-nm particle size. Batch adsorption experiments were conducted over a broad range of pH (2-8) and total lead concentration (10-8-10-4 M) to provide a comprehensive dataset for modeling equilibrium adsorption. Modeling was conducted using both the Langmuir isotherm model and a surface complexation model. Adsorption capacity was most effectively evaluated using the Langmuir model, and adsorption affinity was assessed best through surface complexation modeling. On a mass basis, the adsorption capacity to the nanoparticles was always higher than to the bulk material. However, when adsorption capacity was normalized to surface area, the bulk material had a higher capacity. Among the nanoparticles, the capacity was higher for a material that was pure anatase than for the two materials that were predominantly anatase with additional amounts of rutile. Surface complexation modeling determined a similar trend for adsorption affinity. Adsorption was strongest to the bulk material, followed by the pure anatase nanoparticles, and then the mixed anatase-rutile nanoparticles. For each of the materials, a surface complexation model with only one adjustable parameter provided good fits to the experimental data.
It is well known that soot particles emitted from a diesel engine are usually observed as chain-like aggregates (secondary particles) composed of several tens to hundreds of primary spherical particles. The mature aggregates are not easily eliminated by in-cylinder oxidation. Thus, lowering particulate emission from a diesel engine is difficult. In order to determine whether or not there are effective solutions for reducing soot, the early stage of the formation process before the aggregation needs to be clarified. The authors carried out an ultra-high-resolution electron microscopic observation to analyze the microstructure of diesel soot in further detail. In the present study, the authors adopted two types of TEM techniques to make the microstructure of diesel soot clear: one is a phase-contrast method, and another is a hollow-cone beam method. It was revealed that a primary particle of diesel soot has two distinct parts, each with different structures. The details of these structures are discussed in the Results.
A new method has been developed for the determination of silver ion based on separation and preconcentration with a microcolumn packed with multiwalled carbon nanotubes (MWNTs) prior to its determination by flame atomic absorption spectrometry (FAAS). The optimum experimental parameters for separation and preconcentration of silver, `such as sample pH, sample flow rate and volume, elution conditions, and interfering ions, have been investigated. Silver ion can be quantitatively retained by MWNTs in the pH range 7∼9, and then eluted completely with 1.0 M HNO3. The detection limit of this method for Ag was 0.60 ng mL, and the relative standard deviation (RSD) was 3.8% at the 10 ng mL Ag level. The method has been successfully applied for the determination of trace silver in geological and water samples.
The solubilities of C60 and C70 at 25°C in seven normal alcohols obey the relationship InY = a + bX + cX, where Y is solubility and X is the Hildebrand solubility parameter of the solvent. Extrapolation to the solubility parameter of water yields solubilities in water of 1.3′10 (C60) and 1.3′10(C70) ng/ml with an uncertainty of one order of magnitude.
The potential of multiwalled carbon nanotubes (MWNTs) as a solid-phase extraction adsorbent for the preconcentration of trace Cd, Mn and Ni has been investigated. The studied metal ions can be adsorbed quantitatively on MWNTs at pH 8.0, then eluted completely with 0.5 mol L−1 HNO3. The adsorption capacity of MWNTs was found to be 7.42, 4.86 and 6.89 mg g−1 for Cd, Mn and Ni, respectively. A new method using a microcolumn packed with MWNTs as sorbent has been developed for the preconcentration of trace amounts of Cd, Mn and Ni prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Parameters influencing the preconcentration of the analytes, such as pH of the sample, sample flow rate and volume, elution solution and interfering ions, have been examined. The method has been successfully applied to the determination of trace elements in some environmental samples with satisfactory results.
The main purpose of this study was to characterize the adsorption and desorption interactions of naphthalene, a model environmental organic pollutant, with C60 fullerene. C60 fullerene was used as a model adsorbent for carbonaceous nanoparticles. Typical batch reactors were used to perform adsorption and desorption experiments. Adsorption and desorption of naphthalene to and from C60 fullerene solids in different aggregation forms was studied, where C60 was used as purchased, deposited as a thin film, or dispersed in water by magnetic mixing. Adsorption and desorption of naphthalene to activated carbon, a common sorbent, was also studied and compared with that of C60. It was found in this study that the enhanced dispersal of C60 could affect the adsorption of naphthalene by several orders of magnitude. A solid-water distribution coefficient of 102.4 mL·g-1 was obtained for adsorption of naphthalene to poorly dispersed C60, whereas (104.2 to 104.3) ml·g-1 coefficients were obtained for well-dispersed C60 samples. In addition, desorption of naphthalene from dispersed C60 samples into aqueous solutions was found to exhibit strong hysteresis. For the desorption over a period of 60 days, only about 11% of total naphthalene was desorbed from C60. Possible mechanisms for these observations are discussed.
We describe how, in order for us to determine whether unfunctionalized parent C[sub 60] had any biological activity, we synthesized [sup 14]C-labeled C[sub 60], developed a method to produce a fine aqueous suspension of the labeled material, and then monitored the uptake of the labeled C[sub 60] by human cells. The C[sub 60] became rapidly cell-associated, though it did not affect the proliferation of human keratinocytes or human fibroblasts, indicating that the rapid accumulation of C[sub 60] in human cells does not result in acute toxicity. 17 refs., 1 fig.
All the published data on the solubility of C60 in 140 organic and inorganic solvents are summarized and the critical features of the experimental techniques are treated. Data on die temperature dependence of solubility are also listed and analyzed. Experimental evidences on the molecular state of dissolved C60 as well as the interactions between the solute and solvents are discussed.
The adsorptive potential of multiwalled carbon nanotubes (MWNTs) for solid-phase extraction of bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol was investigated for the first time. The three analytes are quantitatively adsorbed on a MWNTs-packed cartridge, then the analytes retained on the cartridge are quantitatively desorbed with suitable amounts of methanol. Finally, the analytes in the methanol eluate are determined by high performance liquid chromatography-fluoromebric detection. Parameters influencing the extraction efficiency, such as volume of the sample solutions, pH of the sample, and the eluent volume, were examined. Comparative studies showed that MWNTs were superior to C-18 for the extraction of the more polar analyte bisphenol A and at least as effective as C-18 for the extraction of 4-n-nonylphenol and 4-tert-octylphenol. Compared to XAD-2 copolymer, WNTs exhibited a better property for the extraction of all three analytes. The developed method has been applied to determine bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol in several environmental water samples. The accuracy of the proposed method was tested by recovery measurements on spiked samples, and good recovery results (89.8-104.2%) were obtained. Detection limits of 0.083, 0.024, and 0.018 ng mL(-1) for bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol, respectively, were achieved under the optimized conditions.
Carbon nanotubes represent an impressive kind of materials with diverse unexpected properties, and different methods to artificially produce them have been developed. Recently, they have also been synthesized at low temperatures, demonstrating that these materials might exist in fluids or carbon rocks of the Earth’s crust. A new type of natural encapsulated carbon nanotubes found in a coal–petroleum mix is presented. These findings show that all allotropic carbon forms known up to date can be produced in Nature, where pressure, catalysts particles, shear stress and parameters other than exclusively very high temperature, seem to play an important role for producing nanotubes.