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Development of polymeric magnetic adsorbents is a promising approach to obtain efficient treatment of contaminated water. However, the synthesis of magnetic composites involving multiple components frequently involves tedious preparation steps. In the present study, a magnetic chitosan-palygorskite (MCP) nanocomposite was prepared through a straight-forward one pot synthesis approach to evaluate its lead (Pb2+) removal capacity from aqueous solution. The nano-architectural and physicochemical properties of the newly-developed MCP composite were described via micro- and nano-morphological analyses, and crystallinity, surface porosity and magnetic susceptibility measurements. The MCP nanocomposite was capable to remove up to 58.5 mg Pb2+ g−1 of MCP from water with a good agreement of experimental data to the Langmuir isotherm model (R2 = 0.98). The Pb2+ adsorption process on MCP was a multistep diffusion-controlled phenomenon evidenced by the well-fitting of kinetic adsorption data to the intra-particle diffusion model (R2 = 0.96). Thermodynamic analysis suggested that the adsorption process at low Pb2+ concentration was controlled by chemisorption, whereas that at high Pb2+ concentration was dominated by physical adsorption. X-ray photoelectron and Fourier transform infrared spectroscopy results suggested that the Pb adsorption on MCP was governed by surface complexation and chemical reduction mechanisms. During regeneration, the MCP retained 82% Pb2+ adsorption capacity following four adsorption–desorption cycles with ease to recover the adsorbent using its strong magnetic property. These findings highlight the enhanced structural properties of the easily-prepared nanocomposite which holds outstanding potential to be used as an inexpensive and green adsorbent for remediating Pb2+ contaminated water. Refereed/Peer-reviewed

Refereed/Peer-reviewed Poly- and perfluoro alkyl substances (PFAS) are a group of man-made, notoriously persistent, and highly toxic contaminants in the environment reported worldwide. Many adsorbents including granular activated carbon, graphene, biochar, zeolites, and clay minerals have been tested for PFAS removal from water, but most of these materials suffer from high cost and/or poor removal performance. Here, we synthesized, characterized, and examined the efficiency of PCN-222(Fe), a new porous metal organic framework (MOF) with high water stability, for adsorptive removal of a frequently occurring PFAS, perfluorooctane sulfonate (PFOS), from water. The adsorption isotherm and kinetic studies revealed high PFOS adsorption capacity of PCN-222 (2257 mg/g), with rapid PFOS removal rate (within 30 min). The structure of PCN-222 was unaffected in water in the pH range of 2–10 but disintegrated and lost its PFOS removal ability at pH > 10. The PFOS adsorption on PCN-222 was an endothermic reaction. Electrostatic attraction was a dominant mechanism for PFOS adsorption at < 1694 mg/g PFOS concentration, while hydrophobic interaction accompanied with hydrogen-bonding was responsible at ≥ 1694 mg/g PFOS concentration. The interlayer morphology of PCN-222 did not change due to increasing PFOS loading. The findings of this study demonstrated superior features of PCN-222 over other conventional adsorbents for its potential application in removing PFOS from contaminated water to reduce PFOS transfer from water to living organisms.

'Nano Minerals Applications in Pollutants Removal: A New Open Special Issue in

Adsorption behavior of ranitidine hydrochloride (RT) on a Ca-montmorillonite (SAz-1) was studied in aqueous system through batch experiments. The adsorption kinetics revealed that the equilibrium reached within 0.25 h and the data fitted well to the pseudo-second order kinetic equation (R2 = 0.98). The maximum RT adsorption capacity of SAz-1 was 369.2 mg/g and the adsorption isotherm data fol-lowed the Langmuir model (R2 = 0.99). The adsorption of RT and desorption of exchangeable cations from the clay mineral were linearly correlated, suggesting that cation exchange was the dominant mechanism of RT adsorption. The XRD examination of RT-adsorbed SAz-1 samples (unsaturated/saturated) after heat-ing enabled the calculation of RT occupied area in the interlayer of the clay mineral. The results suggested that adsorbed-RT at low loading rate could lay on the internal surfaces in a free style to reduce the basal spacing (d001 value) of SAz-1. When the RT loading rate was increased, a limited surface space enforced more RT molecules to lay in a tilted style and caused interlayer swelling of SAz-1 increasing the d001 value. The trend of rising decomposition temperature of RT with increasing RT loading rates confirmed intercalation of RT molecules in SAz-1. Infrared spectral analysis revealed the participation of amide and furan groups of RT in binding between RT and SAz-1. Thus, this study indicated that SAz-1 is an effi-cient adsorbent to remove RT from contaminated water, and the chain-like molecular structure of RT could cause an irregular change in the basal spacing of swelling type clay minerals. (c) 2022 Elsevier Inc. All rights reserved. Refereed/Peer-reviewed

Purpose: Similar to fresh- and brackish water aquaculture ponds, commercial shrimp farming in degraded saline areas holds the potential to bury carbon (C) in the sediments. However, studies on the mechanisms of sediment C dynamics and C-flux in response to inland saline aquaculture management practices are still scarce. Therefore, the objectives of the present study are to quantify the C burial rate in inland saline aquaculture ponds and assess the impact of inland saline aquaculture on sensitive C fractions in the bottom sediment of the ponds. Materials and methods: The sediment samples (n = 12 from each pond) were collected from six shrimp farming ponds (1000 m2 area of each pond) of different ages. The sediment depth, sediment accumulation rate and the levels of total carbon (TC), total organic carbon (TOC) and sediment oxidizable organic carbon (SOC) and its different fractions were determined using standard procedures. The data were analysed by one-way analysis of variance (ANOVA), followed by the Duncan's multiple range test for comparing the means, and the Pearson correlation test was used to assess the relationship between the different pond sediment parameters and SOC content. Results and discussion: The results revealed that the annual C accumulation rates varied from 902 to 1346 kg C ha−1 year−1 in 7-year-old earthen ponds (EPs) and bottom cemented ponds (BCPs), respectively. The sediment C fractions, including TC, TOC, SOC and its fractions (very labile, VLc; labile, Lc; less labile, LLc), and non-labile carbon (NLc)) were progressively increased over the pond age. The inland saline aquaculture practices over the years increased both active (AC) and passive carbon (PC) pools in the pond sediments, helped in the restoration and improvement of sediment quality and enhanced C sequestration potential of the sediments. Furthermore, a significant increase in the level of particulate organic carbon (POC) in BCPs justified that the non-ploughing practices at BCPs facilitated the formation of macro- and micro-aggregates, thereby increasing the C retention and stability of the pond sediments. Conclusion: This study suggested that the shrimp farming ponds in semi-arid saline soils represented considerable C burial hotspots, enhanced the stable passive C pools and improved the sediment quality. Refereed/Peer-reviewed

usc The accumulation of microplastics (MPs) and nanoplastics (NPs) in terrestrial and aquatic ecosystems has raised concerns because of their adverse effects on ecosystem functions and human health. Plastic waste management has become a universal problem in recent years. Hence, sustainable plastic waste management techniques are vital for achieving the United Nations Sustainable Development Goals. Although many reviews have focused on the occurrence and impact of micro- and nanoplastics (MNPs), there has been limited focus on the management of MNPs. This review first summarizes the ecotoxicological impacts of plastic waste sources and issues related to the sustainable management of MNPs in the environment. This paper then critically evaluates possible approaches for incorporating plastics into the circular economy in order to cope with the problem of plastics. Pollution associated with MNPs can be tackled through source reduction, incorporation of plastics into the circular economy, and suitable waste management. Appropriate infrastructure development, waste valorization, and economically sound plastic waste management techniques and viable alternatives are essential for reducing MNPs in the environment. Policymakers must pay more attention to this critical issue and implement appropriate environmental regulations to achieve environmental sustainability. Refereed/Peer-reviewed

Numerous harmful chemicals are introduced every year in the environment through anthropogenic and geological activities raising global concerns of their ecotoxicological effects and decontamination strategies. Biochar technology has been recognized as an important pillar for recycling of biomass, contributing to the carbon capture and bioenergy industries, and remediation of contaminated soil, sediments and water. This paper aims to critically review the application potential of biochar with a special focus on the synergistic and antagonistic effects on contaminant-degrading microorganisms in single and mixed-contaminated systems. Owing to the high specific surface area, porous structure, and compatible surface chemistry, biochar can support the proliferation and activity of contaminant-degrading microorganisms. A combination of biochar and microorganisms to remove a variety of contaminants has gained popularity in recent years alongside traditional chemical and physical remediation technologies. The microbial compatibility of biochar can be improved by optimizing the surface parameters so that toxic pollutant release is minimized, biofilm formation is encouraged, and microbial populations are enhanced. Biocompatible biochar thus shows potential in the bioremediation of organic contaminants by harboring microbial populations, releasing contaminant-degrading enzymes, and protecting beneficial microorganisms from immediate toxicity of surrounding contaminants. This review recommends that biochar-microorganism co-deployment holds a great potential for the removal of contaminants thereby reducing the risk of organic contaminants to human and environmental health Refereed/Peer-reviewed

Poly- and perfluoroalkyl substances (PFAS) are synthetic chemicals, which reach terrestrial and aquatic environments through anthropogenic activities. Major sources of PFAS in the environment include fire-fighting foams (aqueous film forming foam (AFFF)), wastewater sources, biosolids, and composts. Limited information is available about PFAS in wastewater, which is the focus of this review. PFAS wastewater sources include domestic effluents, industrial effluents, landfill leachates, stormwater, and agricultural effluents through their use in various applications. Land application of PFAS-contaminated wastewater can lead to the contamination of soil and groundwater, thereby reaching the food chain through plant uptake and consumption of potable water. Landfill leachates and industrial effluents contain the highest concentrations of PFAS, posing serious risks to surrounding waterways. Transformation of PFAS precursors can occur through abiotic and biotic processes within the treatment of wastewater, resulting in the formation of harmful PFAS compounds. Currently, there is limited data reported on novel short-chain and ultra-short chain PFAS and PFAS precursors. The strong thermal and chemical stability of PFAS and the complex nature of PFAS mixtures makes the remediation of PFAS in wastewater challenging. However, the review examines and compares current technologies which can treat and remove PFAS from wastewaters. In this review, the distribution, transformation, and remediation of PFAS and their substitutes in wastewater sources are covered. Refereed/Peer-reviewed

Refereed/Peer-reviewed Radioactive elements released into the environment by accidental discharge constitute serious health hazards to humans and other organisms. In this study, three gasified biochars prepared from feedstock mixtures of wood, chicken manure, and food waste, and a KOH-activated biochar (40% food waste + 60% wood biochar (WFWK)) were used to remove cesium (Cs+) and strontium (Sr2+) ions from water. The physicochemical properties of the biochars before and after adsorbing Cs+ and Sr2+ were determined using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, extended X-Ray absorption fine structure (EXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX). The WFWK exhibited the highest adsorption capacity for Cs+ (62.7 mg/g) and Sr2+ (43.0 mg/g) among the biochars tested herein. The removal of radioactive 137Cs and 90Sr exceeded 80% and 47%, respectively, in the presence of competing ions like Na+ and Ca2+. The functional groups present in biochar, including –OH, –NH2, and –COOH, facilitated the adsorption of Cs+ and Sr2+. The Cs K-edge EXAFS spectra revealed that a single coordination shell was assigned to the Cs–O bonding at 3.11 Å, corresponding to an outer-sphere complex formed between Cs and the biochar. The designer biochar WFWK may be used as an effective adsorbent to treat radioactive 137Cs- and 90Sr-contaminated water generated during the operation of nuclear power plants and/or unintentional release, owing to the enrichment effect of the functional groups in biochar via alkaline activation.

Refereed/Peer-reviewed Perfluorooctane sulfonate (PFOS) is a highly persistent contaminant of emerging concern causing harmful effects to human and ecosystem health. In this study, a novel MOF-808 metal–organic framework (MOF) was prepared and evaluated for adsorptive removal of PFOS from aqueous solution. The MOF-808 had high specific surface area (SSA; 1610 m²/g) and was structurally stable in aqueous medium for 7 days under different pH conditions. The MOF-808 reached PFOS adsorption equilibrium within 30 min (at 500 mg/L initial PFOS) and attained the maximum adsorption capacity of 939 mg/g at pH 4.1 – 5.4 (with 50 – 500 mg/L initial PFOS). The PFOS adsorption capacity of MOF-808 was unaffected at pH 2 to 7, but gradually decreased at pH > 7. High SSA, favorable pore size and abundant active adsorption sites on MOF-808 triggered high PFOS adsorption onto the adsorbent. The PFOS adsorption process was endothermic and spontaneous in nature. Electrostatic interaction between the cationic central cluster ([Zr₆O₄(OH)₄]¹²⁺) of MOF-808 and PFOS anion was identified as the key mechanism of PFOS adsorption onto MOF-808, as evident from the infrared spectroscopic investigation of the adsorbent. This study suggests that MOF-808 can be considered as a highly efficient adsorbent for PFOS removal from water and warrants future research to evaluate the application and performance of the material under wastewater conditions.

Fertilizers are indispensable agri-inputs to accomplish the growing food demand. The injudicious use of conventional fertilizer products has resulted in several environmental and human health complications. To mitigate these problems, nanocomposite-based fertilizers are viable alternative options. Nanocomposites, a novel class of materials having improved mechanical strength, barrier properties, and mechanical and thermal stability, are suitable candidates to develop eco-friendly slow/controlled release fertilizer formulations. In this review, the use of different nanocomposite materials developed for nutrient management in agriculture has been summarized with a major focus on their synthesis and characterization techniques, and application aspects in plant nutrition, along with addressing constraints and future opportunities of this domain. Further detailed studies on nanocomposite-based fertilizers are required to evaluate the cost-effective synthesis methods, in-depth field efficacy, environmental fate, stability, etc. before commercialization in the field of agriculture. The present review is expected to help the policy makers and all the stakeholders in the large-scale commercialization and application of nanocomposite-based smart fertilizer products with greater societal acceptance and environmental sustainability in near future.

Soil serves as both a ‘source’ and ‘sink’ for contaminants. As a source, contaminants are derived from both ‘geogenic’ and ‘anthropogenic’ origins. Typically, while some of the inorganic contaminants including potentially toxic elements are derived from geogenic origin (e.g. arsenic and selenium) through weathering of parent materials, the majority of organic (e.g. pesticides and microplastics) as well as inorganic (e.g. lead, cadmium) contaminants are derived from anthropogenic origin. As a sink, soil plays a critical role in the transformation of these contaminants and their subsequent transfer to environmental compartments, including groundwater (e.g. pesticides), surface water (phosphate and nitrate), ocean (e.g. microplastics) and atmosphere (e.g. nitrous oxide emission). A complex transformation process of contaminants in soil involving adsorption, precipitation, redox reactions and biodegradation control the mobility, bioavailability and environmental toxicity of these contaminants. Soil also plays a major role in the decontamination of contaminants, and the ‘cleaning’ action of soil is controlled primarily by the physico-chemical interactions of contaminants with various soil components, and the biochemical transformations facilitated by soil microorganisms. In this article, we examine the geogenic and anthropogenic sources of contaminants reaching the soil, and discuss the role of soil in the sequestration and decontamination of contaminants in relation to various physico-chemical and microbial transformation reactions of contaminants with various soil components. Finally, we propose future actions that would help to maintain the role of soils in protecting the environment from contaminants and delivering sustainable development goals. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.

Refereed/Peer-reviewed Arsenic (As) poses a tremendous threat to human health due to exposure through arsenic-contaminated drinking water and/or food. We aimed to develop organically modified clay adsorbents for the removal of As from aqueous solution. We modified a smectite sample using three organic agents, namely hexadecyl trimethylammonium (HDTMA), chitosan and citric acid, and characterized the products using X-ray diffraction, infrared spectroscopy, and scanning electron microscopy techniques. The characterization techniques suggested successful organic modifications of the smectite sample. The surfactant-modified smectite was the most efficient (66.9%) As removing adsorbent with a maximum adsorption capacity of 473.2 μg g⁻¹. Kinetic study showed that the adsorbents reached As adsorption equilibrium within 3 h, and the data fitted reasonably well to power function and simple Elovich equations (R² > 0.89). The adsorption data were explained well by the Freundlich and Sips isothermal models. The surfactant-modified and chitosan-grafted organoclays adsorbed As by electrostatic attraction and anion exchange, whereas the citric acid activated smectite followed ligand exchange and simple anion exchange mechanisms. This study thus demonstrated the potential of surfactant-modified clays in removing As from contaminated waters.

Nitrate (NO3−) and bicarbonate (HCO3−) are harmful for the water quality and can potentially create negative impacts to aquatic organisms, crops and humans. This study deals with the removal of NO3− and HCO3− from contaminated wastewater using Fe-exchanged nano-bentonite and Fe3O4 nanoparticles. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, surface area measurement and particle size analysis revealed that the adsorbents fall under the nano-scale size range with high specific surface area, and Fe was successfully exchanged in the nano-bentonite clay. The kinetics of adsorption was well defined by pseudo-first order and pseudo-second order kinetic models for both NO3− and HCO3−. The Fe-exchanged nano-bentonite was a better performing adsorbent of the oxyanions than Fe3O4 nanoparticles. According to the Sips isothermal model, the Fe-exchanged nano-bentonite exhibited the highest NO3− and HCO3− adsorption potential of 64.76 mg g-1 and 9.73 meq g-1, respectively, while the respective values for Fe3O4 nanoparticles were 49.90 mg g-1 and 3.07 meq g-1. Thus, inexpensiveness and easy preparation process of Fe-exchanged nano-bentonite make it attractive for NO3− and HCO3− removal from contaminated wastewater with significant environmental and economic benefits.

Amitriptyline (AMI) is one of the most common tricyclic antidepressant personal care medications. Due to its environmental persistence and bioaccumulation, release of AMI into the environment via wastewater streams in elevated levels could lead to significant ecological and human health impacts. In this study, the adsorption of AMI by montmorillonite (SWy-2), a naturally abundant smectite clay with sodium ions as the main interlayer cations, was investigated. Maximum AMI adsorption (276 mg/g) occurred at pH 7-8. After adsorption, examination of the adsorbent's X-ray diffraction pattern indicated that interlayer expansion had occurred, where chemical stoichiometry confirmed cation exchange as the principal adsorption mechanism. AMI adsorption reached equilibrium within 4 h, with kinetic data best fitting the pseudo-second order kinetic model (R-2 = 0.98). AMI adsorption was unaffected by solution pH in the range 2-11, where adsorption was endothermic, and molecular simulations substantiated by Fourier transform infrared spectroscopy and thermogravimetric investigations indicated that the orientation of AMI molecules in the interlayer was via an amine group and a benzene ring. Overall this research shows that SWy-2 has significant potential as a low cost, effective, and geologically derived natural material for AMI removal in wastewater systems. Refereed/Peer-reviewed

Poly- and perfluoroalkyl substances (PFAS) present globally in drinking-, waste-, and groundwater sources are contaminants of emerging concern due to their long-term environmental persistence and toxicity to organisms, including humans. Here we review PFAS occurrence, behavior, and toxicity in various water sources, and critically discuss their removal via mineral adsorbents, including natural aluminosilicate clay minerals, oxidic clays (Al, Fe, and Si oxides), organoclay minerals, and clay-polymer and clay‑carbon (biochar and graphene oxide) composite materials. Among the many remediation technologies, such as reverse osmosis, adsorption, advanced oxidation and biologically active processes, adsorption is the most suitable for PFAS removal in aquatic systems. Treatment strategies using clay minerals and oxidic clays are inexpensive, eco-friendly, and efficient for bulk PFAS removal due to their high surface areas, porosity, and high loading capacity. A comparison of partition coefficient values calculated from extracted data in published literature indicate that organically-modified clay minerals are the best-performing adsorbent for PFAS removal. In this review, we scrutinize the corresponding plausible mechanisms, factors, and challenges affecting the PFAS removal processes, demonstrating that modified clay minerals (e.g., surfactant, amine), including some commercially available products (e.g., FLUORO-SORB®, RemBind®, matCARE™), show good efficacy in PFAS remediation in contaminated media under field conditions. Finally, we propose future research to focus on the challenges of using clay-based adsorbents for PFAS removal from contaminated water due to the regeneration and safe-disposal of spent clay adsorbents is still a major issue, whilst enhancing the PFAS removal efficiency should be an ongoing scientific effort. Refereed/Peer-reviewed

Per- and poly-fluoroalkyl substances (PFAS) are a group of synthetic chemicals found on items like non-stick cookware, fabrics, furniture, carpet stain protectors, food packaging, and firefighting foams. Aqueous film forming foam (AFFF) used in firefighting is a major point source of PFAS input to soil and groundwater. Biosolids and landfills are two other major diffused sources of PFAS input to soil and groundwater sources. At the end of their lifetimes, products containing PFASs may be disposed of to landfill, leading to their appearance in the landfill leachate. Due to the chemical and thermal stability of PFAS and the complexity of PFAS mixtures, remediation of PFAS in both solid and aqueous media is challenging. For aqueous media such as landfill leachates, the most common remediation approach is to use a pump-and-treat method with adsorbents such as granular-activated carbon followed by off-site incineration of the spent activated carbon. Other methods for ex situ PFAS removal include high-pressure expensive membrane treatment using nanofiltration or reverse osmosis. This chapter covers the sources, distribution, and treatment of PFAS in landfill leachate.

Excess phosphorous (P) in aquatic systems causes adverse environmental impacts including eutrophication. This study fabricated Fe(III) loaded chitosan-biochar composite fibers (FBC-N and FBC-C) from paper mill sludge biochar produced under N-2 (BC-N) and CO2 (BC-C) conditions at 600 degrees C for adsorptive removal of phosphate from water. Investigations using SEM/EDX, XPS, Raman spectroscopy, and specific surface area measurement revealed the morphological and physico-chemical characteristics of the adsorbent. The Freundlich isotherm model well described the phosphate adsorption on BC-N, while the Redlich-Peterson model best fitted the data of three other adsorbents. The maximum adsorption capacities were 9.63, 8.56, 16.43, and 19.24 mg P g(-1) for BCN, BC-C, FBC-N, and FBC-C, respectively, indicating better adsorption by Fe(III) loaded chitosan-biochar composite fibers (FBCs) than pristine biochars. The pseudo-first-order kinetic model suitably explained the phosphate adsorption on BC-C and BC-N, while data of FBC-N and FBC-C followed the pseudo-second-order and Elovich model, respectively. Molecular level observations of the P K-edge XANES spectra confirmed that phosphate associated with iron (Fe) minerals (Fe-P) were the primary species in all the adsorbents. This study suggests that FBCs hold high potential as inexpensive and green adsorbents for remediating phosphate in contaminated water, and encourage resource recovery via bio-based management of hazardous waste. usc Refereed/Peer-reviewed

Refereed/Peer-reviewed Soil salinity is one of the major and widespread challenges in the recent era that hinders global food security and environmental sustainability. Worsening the situation, the harmful impacts of climate change accelerate the development of soil salinity, potentially spreading the problem in the near future to currently unaffected regions. This paper aims to synthesise information from published literature about the extent, development mechanisms, and current mitigation strategies for tackling soil salinity, highlighting the opportunities and challenges under climate change situations. Mitigation approaches such as application of amendments, cultivation of tolerant genotypes, suitable irrigation, drainage and land use strategies, conservation agriculture, phytoremediation, and bioremediation techniques have successfully tackled the soil salinity issue, and offered associated benefits of soil carbon sequestration, and conservation and recycling of natural resources. These management practices further improve the socio-economic conditions of the rural farming community in salt-affected areas. We also discuss emerging reclamation strategies such as saline aquaculture integrated with sub surface drainage, tolerant microorganisms integrated with tolerant plant genotypes, integrated agro-farming systems that warrant future research attention to restore the agricultural sustainability and global food security under climate change scenarios

This study evaluates the arsenic adsorption behavior of Fe-exchanged smectite and phosphate-bound kaolinite, in soil, tap water and double distilled water in the presence of competing anions such as silicate, phosphate, and sulfate, and at variable pH values. The maximum amounts of As adsorbed in soil are 620.6 and 607.6 µg g–¹ at pH 5 by Fe-exchanged smectite and phosphate-bound kaolinite, respectively. The pH-modified Freundlich equation fits well (R² > 0.96) to the adsorption data, distinguishing the effect of pH on adsorption. The coefficients of pH-value are 0.04 and 0.05 for phosphate-bound kaolinite and Fe-exchanged smectite, suggesting that low pH is suitable for the adsorption. The As adsorption is decreased in tap water at low pH compared to the soil due to the presence of iron (Fe²⁺/³⁺), sulfate, and bicarbonate in tap water. Among the competing anions in distilled water, phosphate is the most interfering anion for As adsorption. The competition coefficients of As-phosphate binary adsorption derived from the Sheindorf equation are 3.93 and 0.56 for Fe-exchanged smectite and phosphate-bound kaolinite at pH 5. The Fe-exchanged smectite can be used more effectively than phosphate-bound kaolinite for As remediation in systems having low pH (pH ≈5) and high phosphate concentration. Refereed/Peer-reviewed

Terrestrial and aquatic pollution by particulate plastics originates from urban and industrial waste sites, sewage outlets, stormwater, litter transported by systems, and litter discarded by the general public. Nanoplastics and microplastics are tiny plastic particles in different forms like foams, fragments, and fibers. Microplastic by-products include dust from cutting and polishing plastic items and by-products from maintenance of painted metal constructions, such as bridges and buildings, and high pressure washing of painted items. Biodegradable and chemically degradable particulate plastic products are frequently offered as better alternatives to traditional plastic items. Components of the infrastructure, such as stormwater drainage systems and garbage cans, are both contributors to the problem of plastic pollution in the marine environment and important source reduction measures. Particulate plastic solid wastes represent a major environmental problem, but innovations in the treatment and sustainable management of these waste resources can provide economic and social benefits.

Modern agricultural practices use a huge amount of agro-pesticides to control insect pests, pathogens, and unwanted weeds. Many of such agrochemicals persist in the soil and plant systems for long time and pose a risk of migration into the drinking water sources and food chain. Often these agrochemicals occur as a mixture of multiple compounds in the soil due to their simultaneous and/or subsequent seasonal applications. The mobility, fate, and transformation of agrochemicals depend largely on soil types, especially the type and content of soil clays, organic matter content, pH, and microbial activity. The sorption–desorption behaviors of agrochemicals on soil clays, which are the most reactive particle components of soils, may alter significantly when these compounds appear as a mixture. This chapter aims to discuss various soil attributes that control the sorption–desorption of agrochemical contaminants in soils under different soil–plant systems.

Aqueous film-forming foam, used in firefighting, and biowastes, including biosolids, animal and poultry manures, and composts, provide a major source of poly- and perfluoroalkyl substances (PFAS) input to soil. Large amounts of biowastes are added to soil as a source of nutrients and carbon. They also are added as soil amendments to improve soil health and crop productivity. Plant uptake of PFAS through soil application of biowastes is a pathway for animal and human exposure to PFAS. The complexity of PFAS mixtures, and their chemical and thermal stability, make remediation of PFAS in both solid and aqueous matrices challenging. Remediation of PFAS in biowastes, as well as soils treated with these biowastes, can be achieved through preventing and decreasing the concentration of PFAS in biowaste sources (i.e., prevention through source control), mobilization of PFAS in contaminated soil and subsequent removal through leaching (i.e., soil washing) and plant uptake (i.e., phytoremediation), sorption of PFAS, thereby decreasing their mobility and bioavailability (i. e., immobilization), and complete removal through thermal and chemical oxidation (i.e., destruction). In this review, the distribution, bioavailability, and remediation of PFAS in soil receiving solid biowastes, which include biosolids, composts, and manure, are presented. usc Refereed/Peer-reviewed

The use of modified clay minerals for adsorbing arsenic (As) in contaminated soils is an underexplored area of research. The adsorption behavior of As onto inorganically modified smectite and kaolinite both in aqueous and soil media was studied. X-ray diffraction, infra-red spectroscopy, scanning and transmission electron microscopy studies confirmed successful modification of smectite through Fe-exchange and Ti-pillaring, and kaolinite through phosphate binding. The modified smectites were more efficient than phosphate-bound kaolinite in adsorbing As both in water and soil systems. Kinetic study revealed that the clay products reached adsorption equilibrium within 3 h, and the data well fitted to the power function and simple Elovich equation (R 2 > 0.90). The Freundlich isotherm model best described the As adsorption data (R 2 > 0.86) of the modified clay products in both the systems. The Ti-pillared smectite exhibited the highest As adsorption capacity (156.54 μg g − 1 ) in the aqueous medium, while the Fe-exchanged smectite was the best material in the soil system (115.63 μg g − 1 ). The partition coefficient (K d ) and adsorption efficiency (%) data also maintained the similar trend. Precipitation of As and binuclear complex formation also took place in the soil system which made the metalloid non-labile as the time passed. The inorganically modified clay products reported here hold a great potential to adsorb As in contaminated groundwater, drinking water as well as soil. Refereed/Peer-reviewed

Contaminant removal from water involves various technologies among which adsorption is considered to be simple, effective, economical, and sustainable. In recent years, nanocomposites prepared by combining clay minerals and polymers have emerged as a novel technology for cleaning contaminated water. Here, we provide an overview of various types of clay-polymer nanocomposites focusing on their synthesis processes, characteristics, and possible applications in water treatment. By evaluating various mechanisms and factors involved in the decontamination processes, we demonstrate that the nanocomposites can overcome the limitations of individual polymer and clay components such as poor specificity, pH dependence, particle size sensitivity, and low water wettability. We also discuss different regeneration and wastewater treatment options (e.g., membrane, coagulant, and barrier/columns) using clay-polymer nanocomposites. Finally, we provide an economic analysis of the use of these adsorbents and suggest future research directions. usc Refereed/Peer-reviewed

Clays and clay minerals are one of the important groups of materials that are widely used in environmental cleanup applications. The natural clay minerals are hydrophilic in nature, and hold high chemical stability and cation exchange capacity. Owing to the native electronegative surface properties and cation exchange capacities, natural clay minerals are good adsorbents of heavy metal cations and many other cationic organic contaminants. The modification of clay minerals can significantly improve their surface properties that consequently increase their contaminant removal capacities and efficiencies. The current chapter presents a brief overview of various clay modification and surface engineering methods, and discusses how the resultant modified clay products can remediate various environmental contaminants.

Nitrate (NO

Utilization of nanotechnology and nanomaterials is an integral part of modern life. The increased use of nanomaterials in various consumer products, industries, medical instruments, and information technology and energy sectors has created research interest because of their potential toxicity for the environment . Nanomaterials can also be added directly and indirectly to the soil and water treatment plants to reduce pollutant concentrations. Nanoparticles may enter the aquatic system through runoff and industrial effluent discharge, therefore, potentially contaminate both the aquatic and terrestrial systems. Researchers have used laboratory experiments to understand the effect of nanomaterials and their transformation in water and soil environment. The transformation of nanoparticles in the environment involves various physical and chemical processes, and their degradation/transformation products may introduce further toxicity. Various microparticles or host materials can be used to support or coat nanoparticles in order to reduce their toxicity. Microparticles including clay minerals, polymer , carbon -based materials (biochar ) are popular to support nanoparticles due to their large surface area and improved functional characteristics. This chapter aims to give an overview of the risks associated with using nanoparticles , and how to reduce the possible toxicity related to nanoparticles by using microparticle host materials.

ANTICIPATED FUTURE battles in Congress over the Department of Energy’s research funding levels have prompted one of the department’s oldest and largest laboratories, Argonne National Laboratory, to...

LEGISLATION SIGNED by President Barack Obama last week to raise the debt ceiling and avoid a default on government loans presents a mixed bag for science. The deal includes more than $900 billion in cuts over the next decade to federal discretionary funds—money that includes support for science agencies. In terms of an immediate impact, the Budget Control Act of 2011 sets the discretionary spending limit for fiscal 2012 at $1.04 trillion. This is the amount of money Congress can dole out to agencies for the next fiscal year. It is actually $24 million above the amount the House of Representatives set for its 2012 spending limit. Having this essentially flat cap on spending in place provides agencies with some certainty that there will not be huge across-the-board cuts in 2012, a White House official says. As a result, agencies can begin making preliminary spending decisions for 2012. Business leaders also appreciate the certainty the ...