Search

Heavy metal pollution, particularly the excessive release of copper (Cu), is an urgent environmental concern. In this study, sodium lignosulfonate/carboxymethyl sa-son seed gum (SL-Cg-g-PAA) designed for remediation of Cu-contaminated water and soil was successfully synthesized through a free radical polymerization method using lignin as a raw material. This hydrogel exhibits remarkable Cu adsorption capability when applied to water, with a maximum adsorption capacity reaching 172.41 mg/g. Important adsorption mechanisms include surface complexation and electrostatic attraction between Cu(Ⅱ) and oxygen-containing functional groups (–OH, –COOH), as well as cation exchange involving –COONa and –SO 3 Na. Furthermore, SL/Cg-g-PAA effectively mitigated the bioavailability of heavy metals within soil matrices, as evidenced by a notable 14.1% reduction in DTPA extracted state Cu (DTPA-Cu) content in the S4 treatment (0.7% SL/Cg-g-PAA) compared to the control group. Concurrently, the Cu content in both the leaves and roots of pakchoi exhibited substantial decreases of 55.19% and 36.49%, respectively. These effects can be attributed to the precipitation and complexation reactions facilitated by the hydrogel. In summary, this composite hydrogel is highly promising for effective remediation of heavy metal pollution in water and soil, with a particular capability for the immobilization of Cu(Ⅱ) and reduction of its adverse effects on ecosystems. [Display omitted] • A new lignin-based hydrogel (SL-Cg-g-PAA) was successfully synthesized by radical polymerization. • SL-Cg-g-PAA exhibits excellent adsorption capacity for Cu (II) in water. • SL-Cg-g-PAA reduced the content of DTPA extractable Cu in soil. • The content of Cu in various parts of pakchoi is reduced. [ABSTRACT FROM AUTHOR]

The negative impact of refinery wastewater is of great concern to the aquatic, terrestrial, and aerial environment. In this study, N-hexadecylchitosan (NHDC) was successfully synthesized to deal with low mechanical strength, poor adsorption capacity, and limited selectivity of native chitosan. The NHDC was characterized by fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-Ray diffraction analysis (XRD) to study its composition, morphology, and structural attributes. The adsorption of hydrocarbon pollutants from refinery wastewater was studied in batch mode experiments. The results indicated that the removal of COD attained by chitosan and NHDC was 21 and 63%, respectively. COD removal was found to be maximal, i.e., 96% using 0.08 g of NHDC at 60 min in a solution of pH 6.5 maintained at 60 °C. Furthermore, kinetic data revealed that the adsorption system followed pseudo-second order kinetics, whereas equilibrium studies supported both monolayer and multilayer adsorption mechanisms. The designed adsorption platform was able to capture hydrocarbon pollutants under very mild optimized conditions. Furthermore, NHDC demonstrated long term stability when subjected to five successive cycles, which contributed to the sustainability of water treatment systems. On the basis of the outcome of this work, it is advocated that new biobased NHDC can be used as an efficient adsorbent for the remediation of organic contaminants laden wastewater streams generated from oil refineries. [ABSTRACT FROM AUTHOR]

Electrochemical technology is a widely employed technique for remediating soil contaminated with heavy metals. This technology can be utilized alone or in conjunction with other remediation techniques to improve the efficacy of heavy metals removal. The principle of electrochemical remediation technology involves utilization of electromigration, electroosmosis, and electrodialysis effects generated by an external electric field to transfer heavy metals from the soil to electrodes' vicinity. However, this technology has not without limitations and challenges, including low permeability, pH gradient, soil composition, and heavy metal form, among other influencing factors. To overcome these obstacles, novel electrochemical coupling techniques have been proposed and developed, such as incorporating leaching agents, altering electrode materials or structures, employing pulse or alternating current sources. These technologies aim to increase the migration rate of heavy metals, decrease energy consumption, minimize by-products, and enhance the remediation effects. Among these, chemical leaching agents have garnered attention due to their outstanding treatment effects, simple technology, and ease of operation. Consequently, this paper first delineates the advantages of electrochemical technology and leaching technology over traditional adsorption passivation technology from the perspective of the removal mechanism. Secondly, the emphasis was placed on elucidating the technical principles of electrochemical technology and leaching techniques, as well as highlighting the drawbacks and limitations associated with their standalone application. Lastly, a remediation scheme for heavy metal-contaminated soil utilizing electrochemical coupling leaching technology is proposed. The practical significance of this work lies in the fact that electrochemical coupling leaching technology, compared to traditional adsorption passivation techniques, can greatly enhance the efficiency and effectiveness of heavy metal-contaminated soil remediation. It achieves the efficient, rapid, and thorough removal of heavy metal ions from the soil. Electrochemical coupling leaching technology speeds up the chemical leaching process that removes heavy metals from the soil, taking advantage of the best parts of both methods. The electric field then directs, aggregates, and deposits the released heavy metal ions onto electrodes, effectively separating them from the soil. This technology represents a thoroughly effective removal method, capable of avoiding the problem of secondary pollution caused by the re-release of heavy metal ions into the soil due to the changes in external environmental conditions. Therefore, research and application of electrochemical coupling leaching technology hold significant practical and scientific value. [ABSTRACT FROM AUTHOR]

We propose a nucleic acids dilution-induced assembly (NADIA) method for the preparation of lipid nanoparticles. In the conventional method, water-soluble polymers such as nucleic acids and proteins are mixed in the aqueous phase. In contrast, the NADIA method, in which self-assembly is triggered upon dilution, requires dispersion in an alcohol phase without precipitation. We then investigated several alcohols and discovered that propylene glycol combined with sodium chloride enabled the dispersion of plasmid DNA and protamine sulfate in the alcohol phase. The streamlined characteristics of the NADIA method enable the preparation of extracellular vesicles-mimicking lipid nanoparticles (ELNPs). Among the mixing methods using a micropipette, a syringe pump, and a microfluidic device, the lattermost was the best for decreasing batch-to-batch differences in size, polydispersity index, and transfection efficiency in HepG2 cells. Although ELNPs possessed negative ζ-potentials and did not have surface antigens, their transfection efficiency was comparable to that of cationic lipoplexes. We observed that lipid raft-mediated endocytosis and macropinocytosis contributed to the transfection of ELNPs. Our strategy may overcome the hurdles linked to supply and quality owing to the low abundance and heterogeneity in cell-based extracellular vesicles production, making it a reliable and scalable method for the pharmaceutical manufacture of such complex formulations. [ABSTRACT FROM AUTHOR]

Cadmium is a highly toxic metal, and its presence can have adverse effects on both human health and aquatic ecosystems. The efficient removal of cadmium from wastewater is therefore of crucial importance, but traditional methods have proved to be inadequate. Thus, technologies for the treatment of wastewater containing cadmium, including adsorption, have been developed. The aim of this study was the preparation of a polymeric material by the grafting reaction of κ-carrageenan and its use as an adsorbent for cadmium removal. This was performed to study the removal capacity of cadmium ions in synthetic solutions, as well as the effects of pH and ions on adsorption capacity, adsorption kinetics, isotherms, and reusability. Additionally, the disinfectant potential of the solution was evaluated for the inactivation of total coliforms and E. coli in river water. The best adsorption capacity was 75.52 ± 1.325 mg g−1, with the kinetics described by the pseudo-second order model. Maximum adsorption capacity (127.6 ± 1.833 mg g−1) and RL (0.0113) were determined using the Langmuir model, the Freundlich model was the one that best fits the experimental data and indicated cooperative adsorption, and the Dubinin-Radushkevich isotherm was used to obtain the adsorption energy and identify that it is physical. The presence of ions K+, Na+, Mg2+, and Ca2+ in a concentration of 0.5% decreased the adsorption capacity, and that at pH 2.0, the adsorption capacity was drastically reduced. The study indicates that the polymer has potential as an adsorbent for removing cadmium from aqueous solutions and exhibits self-disinfecting properties. [ABSTRACT FROM AUTHOR]

Halmahera Island in Indonesia holds great potential for nickel laterite due to its geological setting. As the product of chemical weathering, nickel laterite can be divided into saprolite and limonite. Despite containing invaluable elements like nickel and cobalt, limonite ore is seldom used in metal production. This study evaluates these two elements' leaching behavior and kinetics from the Halmahera deposit. Limonite ore was leached using 50 mL of 0.5 M sulfuric acid at an S/L ratio of 10% and 20%. The leaching process was conducted at 30°C, 50°C, and 80°C. The experimental results showed that the highest recovery for cobalt and nickel was 100% in the adequate presence of H+ ions. The result shows that sulfuric acid is more selective to cobalt than a nickel. The shrinking core ash diffusion model represents the leaching kinetics of cobalt, while nickel recovery follows the Kröger-Ziegler kinetics model. [ABSTRACT FROM AUTHOR]

Iron (Fe) plays an important role in the biogeochemical cycling of carbon and nutrients in aquatic systems. Reactive Fe phases can interact with organic carbon and facilitate the removal of carbon from the biogeochemical cycle; however, this important ecosystem function is often strongly controlled by Fe availability. Due to pollution from lignite mining in the Lusatian province in Northeast Germany, large amounts of iron and sulfate are released into the fluvial-lacustrine system of the Spree River. It was hypothesized that the input of freshly precipitated iron oxyhydroxides from mining areas (e.g., ferrihydrite) alter the biodegradation of particulate organic matter (POM) in downstream lacustrine sediments. To investigate the Fe-dependent degradation of POM, slurries mimicking iron-polluted sediments (85 mg Fe per g, 116 mg Fe per g, and 149 mg Fe per g dry weight) were incubated with plankton or leaf POM under anoxic and oxic headspace conditions, and CO2 and CH4 emissions, water chemistry, and stable isotopes of dissolved inorganic carbon were measured. The experiments revealed that (i) with an increasing Fe content, the CO2 and CH4 emissions were gradually reduced, (ii) CO2 and CH4 production was higher during plankton degradation than during leaf decomposition, and (iii) under oxic conditions, CO2 production was higher and CH4 production was lower when compared to the treatments under anoxic conditions. These findings demonstrate that while benthic mineralization of fresh POM typically releases greenhouse gases into the water column, the availability of iron oxyhydroxides can contribute to reduced greenhouse gas emissions from sediments. This is of considerable relevance for future carbon budgets of similar mining-affected, iron-polluted fluvial-lacustrine river systems. [ABSTRACT FROM AUTHOR]

The current report provides the synthesis and characterization of palm tree leaves biochar (PL-BC) prepared by simple thermal pyrolysis at 550 °C, which was then used for the elimination of lead and chromium from aqueous solution. An advanced material characterization was conducted by XPS, SEM, EDS, and FT-IR for the raw and spent PL-BC. Moreover, detailed surface chemical state analysis and identification of the chemical species was conducted by the XPS. The XPS surface analysis revealed high carbon content 78.5% while the BET surface area was 21.6 m2/g. The surface oxygen content was about 15.7% suggesting the abundance of oxygen functional groups onto the PL-BC. The adsorption results demonstrated that the removal of lead and chromium by PL-BC obeyed to Freundlich model, while kinetics data obeyed to pseudo-second order model. Furthermore, the Freundlich maximum adsorption uptakes for lead and chromium were 79.2 mg/g and 51.9 mg/g, respectively. The reusability studies demonstrated that more than 64% of the initial remediation efficiency of lead and chromium can be achieved after five adsorption/desorption cycles. Moreover, the PL-BC was able to reduce the lead and chromium content from injected actual brackish water of 1 mg/L to the international allowable limits of drinking water (˂50 µg/L). The remediation of lead and chromium by PL-BC was controlled by physical and chemical adsorption processes and dominated by complexation, precipitation, and ion exchange. These outcomes disclose the mechanism of lead and chromium removal by PL-BC and provide a sustainable solution of utilizing agriculture waste in water treatment. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) primarily achieve efficient wastewater purification through synergistic interactions among substrates, plants, and microorganisms. Serving as the structural foundation of the entire wetland system, substrates not only provide a growth medium for plants, but also serve as adhesive carriers for microorganisms and habitats for animal activities. Research on substrates has attracted considerable attention; however, in practical engineering applications, the selection of substrates often depend on personal experience, which may lead to significant gaps in the effectiveness of wetland systems in treating different characteristic contaminants. Therefore, it is of great significance to investigate the influence of substrates on the removal of contaminants in sewage and identify substrate materials with good physical and chemical properties to optimize the design and operation of CWs-based sewage-treatment systems and improve their purification efficiency. In this review, bibliometric analysis was conducted to using the Web of Science database and VOSviewer_1.6.20 software to assess the progress of research on CWs. This article provides a comprehensive overview of substrate types and characteristics based on recent research advancements in the field. Additionally, it discusses removal methods and the influence of factors related to conventional contaminants (COD, nitrogen, and phosphorus), heavy metals (HMs), fluorinated compounds, pharmaceuticals, personal care products (PPCPs), and microplastics. A thorough evaluation was conducted on the economic costs of various substrates and their ability to remove major contaminants from water bodies, providing a reference for the further development of wetland technology. [ABSTRACT FROM AUTHOR]

Wheat straw returning is a common agronomic measure in the farmland. Understanding organic carbon transformation is of great significance for carbon budget under the premise of widespread distribution of cadmium (Cd) contaminated soils. An incubation experiment was conducted to assess the influence of Cd contamination on the decomposition and accumulation of total organic carbon (TOC) as well as the composition and abundance of bacterial communities in eight soil types with wheat straw addition. The results showed that inhibition of Cd contamination on microbially mediated organic carbon decomposition was affected by soil types. The lower cumulative C mineralization and higher TOC content could be observed in the acidic soils relative to that in the alkaline soils. The content of Cd in soil exhibits different effects on the inhibition in decomposition of TOC. The high dosage level of Cd had stronger inhibitory impact due to its high toxicity. The decomposition of TOC was restricted by a reduction in soil bacterial abundance and weakening of bacterial activities. Redundancy analysis (RDA) indicated that Proteobacteria and Gemmatimonadetes were abundant in alkaline Cd-contaminated soils with wheat straw addition, while Bacteroidetes dominated cumulative C mineralization in acidic Cd-contamination soils. Moreover, the abundance of predicted functional bacteria indicated that high-dose Cd-contamination and acid environment all inhibited the decomposition of TOC. The present study suggested that pH played an important role on carbon dynamics in the Cd-contaminated soils with wheat straw addition. [ABSTRACT FROM AUTHOR]

Bulk doping of aluminum ions (Al3+) is promising to solve the problems of poor safety and short cycling life of nickel-rich cathodes. A crucial chelating agent of sodium lactate is found here to realize the best co-precipitation of Al3+ with other transition-metal ions at an atomic level for the first time. The discharge capacity of this cathode is increased by 13.17% at 1 C, while its cycle retention is promoted by 12.76% compared to a commercial counterpart. Additionally, the amount of chelating agent complexed with Al3+ is optimized, and the gradient directions of Al-doping for the full concentration gradient materials are also investigated. It is found that the gradually increased Al3+ concentration from core to shell can integrate the surface coating and bulk doping, improving the electrochemical performance. Its discharge capacity is 149.3 mAh/g at a high rate of 5 C. An approach for bulk Al-doping and synthesis of commercial NCA cathode materials is provided. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the impact of MgO 0.5 g/kg loaded in different organic waste materials on the properties of the modified biochars obtained. The waste materials included tea waste, wood waste, water chestnut peel, and pomegranate peel, which were used to create tea waste MgO-modified biochar (TWMgO-MBC), wood waste MgO-modified biochar (WSMgO-MBC), water chestnut peel MgO-modified biochar (WCMgO-MBC), and pomegranate peel MgO-modified biochar (PPMgO-MBC). All the MgO-modified biochars were prepared at 600 °C for 2 h and applied at 0.5 and 1% doses for the immobilization of Ni, Cu, Pb, and Cr in stone crushing and mining-polluted soil and the reduction in their uptake by pearl millet (Pennisetum glaucum) plant. The greatest fresh and dry biomasses were observed at 45.04% and 31.29%, respectively, with the application of TWMgO-MBC 1% in stone-crushing-polluted soil. The highest degree of immobilization of Ni (76.67%) was observed for the WSMgO-MBC 1% treatment, Cu (73.45%) for WCMgO-MBC 1%, Pb (76.78%) for WSMgO-MBC 1%, and Cr (70.55%) for WCMgO-MBC 1%, in comparison with the control. The maximum uptake of Ni, Cu, Pb, and Cr in the shoot of pearl millet was reduced by 78.43% with WSMgO-MBC 1%, 75.06% with WSMgO-MBC 1%, 90.81% with WCMgO-MBC 1%, and 85.71% with WSMgO-MBC 1% as compared with the control. The greatest reduction in Ni, Cu, Pb, and Cr in the root of pearl millet was observed at 77.81% with WSMgO-MBC 1%, 68.09% with WCMgO-MBC 1%, 84.03% with WCMgO-MBC 1%, and 88.73% with WCMgO-MBC 1%, in comparison with the control. The present study demonstrated that the TWMgO-MBC 1% treatment was highly effective for improving plant growth, while the WSMgO-MBC 1%, and WCMgO-MBC 1% treatments were found to be highly effective for immobilizing heavy metals in polluted soils, thus facilitating safe crop cultivation. Future studies should concentrate on the long-term application of MgO-modified biochars for the remediation of multimetal-polluted soils. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a highly toxic contaminant posing serious ecological and human health risks. This study investigates the Hg transfer characteristics and prediction models in a soil–lettuce system, employing bioconcentration factors (BCF), path analysis (PA), and Freundlich-type functions. A pot experiment was conducted in a greenhouse, where lettuce was grown in a range of Chinese agricultural soils (n = 21) and deliberately spiked with Hg using Hg(NO3)2 solution. The results indicated that lettuce grown in Hg-spiked acidic soils (pH < 6.5) accumulated total Hg (THg) levels up to 14.01 µg kg−1, surpassing the safe consumption limit of 10 µg kg−1. The BCF for lettuce THg was less than 1.0, suggesting a low transfer of Hg from soil to lettuce. Notably, BCF values were significantly higher in acidic soils (0.02) compared to alkaline soils (0.005). Path analysis accounted for 82% of the variation in lettuce THg content, identifying soil THg, pH, and amorphous (Amo) Al and Fe oxides as primary direct factors. Additionally, soil-available Hg (AvHg), exchangeable Hg (ExHg), clay, and organic matter (OM) were significant indirect factors affecting lettuce THg content. To validate the findings of the path analysis, an extended Freundlich-type equation was developed using stepwise multiple linear regression (SMLR). This model exhibited high predictive accuracy (R2 = 0.82, p ≤ 0.001), with soil pH, THg, and amorphous Al and Fe oxides being the key variables for predicting Hg transfer in the soil–lettuce system. The insights from this study can guide the management of safe lettuce production in Hg-contaminated soils, ensuring the mitigation of Hg exposure through agricultural produce. [ABSTRACT FROM AUTHOR]

The technosphere consists of material stocks accumulated by human activities, which can include processing residue, such as slag. Various smelting processes generate slag, and some valuable elements are concentrated in this by-product. In this review, the extraction of critical and strategic metals from non-ferrous slags is discussed. Critical and strategic metals are materials that are vital for the nation's economy and defence, as well as its industries, and have common features, such as expected shortfalls, increasing demand, and few substitutions. There are several definitions, methods, and classifications of critical and strategic elements by different organisations. In this study, reports from seven institutions around the world are summarised, and a list of recommended critical and strategic metals is presented. Non-ferrous slags contain a considerable amount of critical and strategic elements, and research on technology and process development using both pyro- and hydrometallurgical methods is very attractive. When it comes to the extraction of values from slag and the development of technology, it is not only important to consider the economic aspect but also to ensure the processes are low in emissions and energy consumption but high in efficiency and recycling. [ABSTRACT FROM AUTHOR]

The extensive consumption of chicken has resulted in the emergence of a significant environmental issue in the form of chicken feather waste. As such, there is an urgent need for the development of green treatment and recycling methods for chicken feathers. Chicken feathers can serve as a type of heteroatomic doping carbon source, making them an excellent candidate for the electrode materials used in electrochemical energy devices. Furthermore, their unique structures and functional groups make them highly promising for use as adsorbents, electronics, and building materials. In this paper, we provide a summary and review of recent progress made in the use of chicken feathers for energy and environmental applications. Based on the theoretical knowledge and practical applications presented in this review, promising green recycling processes of chicken feathers can be developed. These processes can help to reduce environmental pollution and promote sustainable development. [ABSTRACT FROM AUTHOR]

Landfill leachate, which is a complicated organic sewage water, presents substantial dangers to human health and the environment if not properly handled. Electrochemical technology has arisen as a promising strategy for effectively mitigating contaminants in landfill leachate. In this comprehensive review, we explore various theoretical and practical aspects of methods for treating landfill leachate. This exploration includes examining their performance, mechanisms, applications, associated challenges, existing issues, and potential strategies for enhancement, particularly in terms of cost-effectiveness. In addition, this critique provides a comparative investigation between these treatment approaches and the utilization of diverse kinds of microbial fuel cells (MFCs) in terms of their effectiveness in treating landfill leachate and generating power. The examination of these technologies also extends to their use in diverse global contexts, providing insights into operational parameters and regional variations. This extensive assessment serves the primary goal of assisting researchers in understanding the optimal methods for treating landfill leachate and comparing them to different types of MFCs. It offers a valuable resource for the large-scale design and implementation of processes that ensure both the safe treatment of landfill leachate and the generation of electricity. The review not only provides an overview of the current state of landfill leachate treatment but also identifies key challenges and sets the stage for future research directions, ultimately contributing to more sustainable and effective solutions in the management of this critical environmental issue. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE) waste and chicken eggshell were used to synthesize three novel adsorbents, namely mesoporous graphene (MG), nano-eggshell modified graphene (nEMG), and nano-magnetic eggshell modified graphene (nM-EMG) for methyl red (MR) adsorption from simulated wastewater. The effects of adsorption conditions (pH, contact time, initial dye concentration, adsorbent dose, and temperature) were investigated. MG, nEMG, and nM-EMG were characterized using SEM, TEM, BET, EDX, XRD, and FTIR analyses. MG, nEMG, and nM-EMG had specific surface areas of 15, 31, and 179 m2/g and mean pore diameters of 27, 29, and 5 nm respectively. The equilibrium adsorption capacities of MG, nEMG, and nM-EMG were 5.6, 8.1, and 6.5 mg/g respectively at MR concentration of 100 mg/L, pH 4, adsorbent dose of 1.0 g/100 mL, and temperature of 25 °C. All MR sorption processes followed the pseudo-second-order and Langmuir–Freundlich model. The adsorption rates were controlled by intra-particle and film diffusion. MR uptake on the synthesized adsorbents was spontaneous, endothermic, and chemisorption. The adsorption occurred via electrostatic interactions, π electron interactions, and hydrogen bonding. The performance of the prepared adsorbents was examined in different water matrices and compared with other MR adsorbents. After five regeneration cycles, the adsorbent reusability study showed that nM-EMG is the most stable and reusable adsorbent. [ABSTRACT FROM AUTHOR]

To develop a market for biochar, it is imperative that solutions are found to producing biochars that are both high performance and economically viable. While biochar performance can be enhanced via chemical modification, it is likely that optimization of pyrolysis time and temperature is a more cost-effective approach to enhancing performance. This was explored via the transformation of urban garden waste into biochar using a range of preparation conditions (heating temperature, residence time, and heating rate). Biochar yield and Cd2+ adsorption performance were optimized using response surface methodology. The "best compromise" yield and Cd2+ adsorption performance (49.9% and 40.0 mg/g, respectively) of garden waste biochar were achieved using preparation conditions of 398 ℃, 10 ℃/min, and 30 min. In addition, the quantification of adsorption mechanisms suggested mineral precipitation, ion exchange, functional group complexation, and physical adsorption, accounted for 47.9%, 41.5%, 10.3%, and 0.3% of total adsorbed Cd2+ in biochar, respectively. Overall, transformation of garden waste into adsorbents might offer a new market for the utilization of urban garden waste, especially given the size of this waste stream and the challenges it presents to municipal administrations. [ABSTRACT FROM AUTHOR]

Ball milling, as a cost-effective and eco-friendly approach, has been popular in materials synthesis to solve problems involving toxic reagents, high temperatures, or high pressure, which has the potential for large-scale production. However, there are few reviews specifically concentrating on the latest progress in materials characteristics before and after ball milling as well as the adsorptive application for aqueous pollutants. Hence, this paper summarized the principle and classification of ball milling and reviewed the advances of mechanochemical materials in categories as well as their adsorption performance of organic and inorganic pollutants. Ball milling has the capacity to change materials' crystal structure, specific surface areas, pore volumes, and particle sizes and even promote grafting reactions to obtain functional groups to surfaces. This improved the adsorption amount, changed the equilibrium time, and strengthened the adsorption force for contaminants. Most studies showed that the Langmuir model and pseudo-second-order model fitted experimental data well. The regeneration methods include ball milling and thermal and solvent methods. The potential future developments in this field were also proposed. This work tries to review the latest advances in ball-milled materials and their application for pollutant adsorption and provides a comprehensive understanding of the physicochemical properties of materials before and after ball milling, as well as their effects on pollutants' adsorption behavior. This is conducive to laying a foundation for further research on water decontamination by ball-milled materials. [ABSTRACT FROM AUTHOR]

Stabilizing materials were prepared by different ratios of attapulgite/humic acid composites, and the optimum proportion for the remediation of Cd-polluted soils was found. The results suggested that the bioavailability of Cd in soil was decreased by the application of material prepared with humic acid and attapulgite in a ratio of 1:5. CaCl2-Cd, diethylenetriaminepentaacetic acid (DTPA-Cd) and the toxicity characteristic leaching procedure (TCLP-Cd) were reduced by 34.03%, 26.62% and 43.66%, and the ecological risk was depressed accordingly. The addition of stabilizing materials could transform the acid-soluble and reducible speciation to residue speciation, with a ratio of 1:5, significantly increasing the residue proportion of Cd in soil. The content of the residue state was increased by 63.13%, and the content of the acid-soluble state was significantly decreased by 34.10% compared with the control. The bioavailability, acid-soluble and reducible speciation of Cd had a highly negative correlation with the growth of corn, and the accumulation of Cd in corn had a significantly negative correlation with the residue speciation. Attapulgite/humic acid composites can reduce the bioavailability and increase the ratio of residue Cd in soil effectively, and they have the potential to remediate the pollution of heavy metals in soil. [ABSTRACT FROM AUTHOR]

The accumulation of arsenic (As) in rice (Oryza sativa L.) grain poses a significant health concern in Bangladesh. To address this, we investigated the efficacy of various organic amendments and phytoremediation techniques in reducing As buildup in O. sativa. We evaluated the impact of five doses of biochar (BC; BC0.1: 0.1%, BC0.28: 0.28%, BC0.55: 0.55%, BC0.82: 0.82% and BC1.0: 1.0%, w/w), vermicompost (VC; VC1.0: 1.0%, VC1.8: 1.8%, VC3.0: 3.0%, VC4.2: 4.2% and VC5.0: 5.0%, w/w), and floating duckweed (DW; DW100: 100, DW160: 160, DW250: 250, DW340: 340 and DW400: 400 g m− 2) on O. sativa cultivated in As-contaminated soil. Employing a three-factor five-level central composite design and response surface methodology (RSM), we optimized the application rates of BC-VC-DW. Our findings revealed that As contamination in the soil negatively impacted O. sativa growth. However, the addition of BC, VC, and DW significantly enhanced plant morphological parameters, SPAD value, and grain yield per pot. Notably, a combination of moderate BC-DW and high VC (BC0.55VC5DW250) increased grain yield by 44.4% compared to the control (BC0VC0DW0). As contamination increased root, straw, and grain As levels, and oxidative stress in O. sativa leaves. However, treatment BC0.82VC4.2DW340 significantly reduced grain As (G-As) by 56%, leaf hydrogen peroxide by 71%, and malondialdehyde by 50% compared to the control. Lower doses of BC-VC-DW (BC0.28VC1.8DW160) increased antioxidant enzyme activities, while moderate to high doses resulted in a decline in these activities. Bioconcentration and translocation factors below 1 indicated limited As uptake and translocation in plant tissues. Through RSM optimization, we determined that optimal doses of BC (0.76%), VC (4.62%), and DW (290.0 g m− 2) could maximize grain yield (32.96 g pot− 1, 44% higher than control) and minimize G-As content (0.189 mg kg− 1, 54% lower than control). These findings underscore effective strategies for enhancing yield and reducing As accumulation in grains from contaminated areas, thereby ensuring agricultural productivity, human health, and long-term sustainability. Overall, our study contributes to safer food production and improved public health in As-affected regions. [ABSTRACT FROM AUTHOR]

Biochar (BC) is a well-established physical treatment method. The high-cost BC limits their use as adsorbents in wastewater. Thus, deriving BC from cheap and locally available waste materials is needed to develop a feasible waste removal technology. Nowadays, BC technology makes it possible to envision a new strategy to manage invasive plants by converting them into value-added products like BC. Hence, the present study was designed to evaluate the potential utilization of BC as an efficient filter medium made by invasive aquatic plants, Salvinia spp., and Eichhornia spp. A mass of 50 g of prepared activated and nonactivated BC was incorporated in a sand and gravel filter to treat rubber-manufactured wastewater. Wastewater was passed through the filter, and both raw and treated water samples were analyzed for pH, Total Suspended Solids (TSS), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), Ammoniacal- Nitrogen (NH3-N), Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Phosphates (TP), Nitrate (NO3-N), turbidity and heavy metals (Zinc, Chromium). The control filter was developed only with sand and gravel, excluding BC. Fourier Transform-Infrared Spectroscopy (FT-IR) and Scanning electron microscopy (SEM) were used to analyze BC's chemical and physical characteristics. A brine shrimp lethality assay was carried out for toxicological evaluation. OH stretching (3,550-3,200 cm-1), C=C aromatic stretching (1400-1660 cm-1), and Phenol-O-H bending (1,300-1,400 cm-1) were recorded in all BC samples that involved the adsorption mechanism. Observed images indicated differences in surface morphology of both activated and nonactivated BC were observed under SEM observation. The study concludes that the filter unit incorporated with activated Eichhornia spp. Gave the best treatment efficiency when compared to filter units incorporated with other activated and nonactivated BC. The toxicity assay revealed 100% mortality in the control setup and raw wastewater but only 60-70% in the nonactivated BC integrated filters. Activated BCincorporated filters showed no mortalities. Hence, the study's outcomes suggest a green approach using invasive aquatic plants for sustainable wastewater treatment. [ABSTRACT FROM AUTHOR]

The removal of low concentrations of rare-earth ions (e.g., Er(III)) from water has stimulated interest in the field of mineral processing and water treatment. Here, an ion-exchange and complexation-assisted precipitation method for the removal of low concentrations of Er(III) from water using heptadecyl-1,1-bisphosphonic acid (HBPA) was investigated. The results showed that effective cation-exchange between Er(III) ions and the bisphosphonate headgroup was achieved, and the solution pH abruptly decreased from 6.5 to around 3.1 at the first stage, which further led to the formation of less soluble Er(III) heptadecyl-1,1-bisphosphonate complexes. While low concentrations of Er(III) ions in water are typically treated by the addition of HBPA, followed by the addition of sodium bicarbonate (adjusting the pH to 6–8) and activate carbon, Er(III) ions could be efficiently removed from aqueous solution after about 30 min based on the cation-exchange and complexation-assisted precipitation method. Additionally, the removal of ultra trace amounts of Er(III) ions was not significantly affected by coexisting trace amounts of alkaline-earth metal ions (Mg2+, Ca2+ and Sr2+). HBPA is an effective Er(III) chelator, which may be a potential and promising alternative technique to remove Er(III) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

A new idea to alleviate environmental pollution is the development of low-cost adsorbents using natural minerals and fishery wastes to treat high concentrations of heavy metal pollutants in acid mine drainage (AMD). Adsorbent morphology, adsorptive and regenerative capacity, and application potential are limiting factors for their large-scale use. Oyster shells capable of releasing alkalinity were loaded on the surface of lignite to develop two composite adsorbents with different morphologies (powdery and globular) for the treatment of AMD containing Pb(II) and Cd(II). The results show that the ability of the adsorbent to treat AMD is closely related to its morphologies. The pseudo-second-order kinetic model and the Langmuir model are suitable to describe the adsorption process of OS-M(P), and the maximum adsorption saturation capacities of Pb(II) and Cd(II) are 332.6219 mg/g and 318.9854 mg/g, respectively. The pseudo-second-order kinetic model and the Freundlich model are suitable to describe the adsorption process of OS-M(G). A synergistic result of electrostatic adsorption, neutralization precipitation, ion exchange and complex reaction is achieved in the removal of Pb(II) and Cd(II) by two morphologies of adsorbents. The regeneration times (5 times) and recovery rate (75.75%) of OS-M(G) are higher than those of OS-M(P) (3 times) and recovery rate (20%). The ability of OS-M(G) to treat actual AMD wastewater is still better than that of OS-M(P). OS-M(G) can be used as a promising environmentally friendly adsorbent for the long-term remediation of AMD. This study provides a comprehensive picture of resource management and reuse opportunities for natural mineral and fishery wastes. [ABSTRACT FROM AUTHOR]

This study presents an analysis of soil contamination caused by Ni, Zn, Cd, Cu, and Pb at municipal solid waste (MSW) landfills, with a focus on ecological risk assessment. The approach aims to assess how different landfill practices and environmental conditions affect soil contamination with potentially toxic elements (PTEs) and associated environmental risks. Soil samples were collected from MSW landfills in Poland and the Czech Republic. The research included a comprehensive assessment of PTEs in soils in the context of global environmental regulations. The degree of soil contamination by PTEs was assessed using indices: Geoaccumulation Index (Igeo), Single Pollution Index (Pi), Nemerow Pollution Index (PN), and Load Capacity of a Pollutant (PLI). The ecological risk was determined using the Risk of PTEs (ERi) and Sum of Individual Potential Risk Factors (ERI). The maximum values of the indicators observed for the Radiowo landfill were as follows: Igeo = 4.04 for Cd, Pi = 24.80 for Cd, PN = 18.22 for Cd, PLI = 2.66, ERi = 744 for Cd, ERI = 771.80. The maximum values of the indicators observed for the Zdounky landfill were as follows: Igeo = 1.04 for Cu, Pi = 3.10 for Cu, PN = 2.52 for Cu, PLI = 0.27, ERi = 25 for Cd, ERI = 41.86. The soils of the tested landfills were considered to be non-saline, with electrical conductivity (EC) values less than 2,000 μS/cm. Varying levels of PTEs were observed, and geostatistical analysis highlighted hotspots indicating pollution sources. Elevated concentrations of Cd in the soil indicated potential ecological risks. Concentrations of Cu and lead Pb were well below the thresholds set by the environmental legislation in several countries. In addition, Ni concentrations in the soils of both landfills indicated that the average levels were within acceptable limits. Principal Component Analysis (PCA) revealed common sources of PTEs. The identification of specific risk points at the Radiowo and Zdounky sites contributes to a better understanding of potential hazards in landfill environments. By establishing buffer zones and implementing regular maintenance programs, emerging environmental problems can be addressed in a timely manner. [ABSTRACT FROM AUTHOR]

The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate–ammonia complex (tetraamminecopper (II) sulfate monohydrate, [Cu(NH3)4]SO4·H2O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form ([Cu(NH3)4]-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon ([Cu(NH3)4]-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, [Cu(NH3)4]-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and [Cu(NH3)4]-PAC diminished progressively with rising ionic strength. Modified activated carbon [Cu(NH3)4]-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms. [ABSTRACT FROM AUTHOR]

Sustainable food security and safety are major concerns on a global scale, especially in developed nations. Adverse agroclimatic conditions affect the largest agricultural-producing areas, which reduces the production of crops. Achieving sustainable food safety is challenging because of several factors, such as soil flooding/waterlogging, ultraviolet (UV) rays, acidic/sodic soil, hazardous ions, low and high temperatures, and nutritional imbalances. Plant growth- promoting rhizobacteria (PGPR) are widely employed in in-vitro conditions because they are widely recognized as a more environmentally and sustainably friendly approach to increasing crop yield in contaminated and fertile soil. Conversely, the use of nanoparticles (NPs) as an amendment in the soil has recently been proposed as an economical way to enhance the texture of the soil and improving agricultural yields. Nowadays, various research experiments have combined or individually applied with the PGPR and NPs for balancing soil elements and crop yield in response to control and adverse situations, with the expectation that both additives might perform well together. According to several research findings, interactive applications significantly increase sustainable crop yields more than PGPR or NPs alone. The present review summarized the functional and mechanistic basis of the interactive role of PGPR and NPs. However, this article focused on the potential of the research direction to realize the possible interaction of PGPR and NPs at a large scale in the upcoming years. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the main hazards affecting the sustainable development of agriculture in the Hetao Irrigation District (HID) of Inner Mongolia. To grasp the water and salt transport patterns and spatial–temporal distribution characteristics of the HID at the regional scale, the improved Soil and Water Assessment Tool with a salinity module (SWAT-Salt) model was used to establish the distributed water and salt transport model for the watershed in this study. The results demonstrated that the modified model could more accurately represent the process of water and salt changes in the HID. The coefficient of determination (R2) in the simulation of streamflow and discharge salt loading was 0.83 and 0.86, respectively, and the Nash–Sutcliffe efficiency (NSE) was 0.80 and 0.74, respectively. Based on this, different hydrological processes (surface runoff, lateral flow, groundwater, soil seepage) as well as spatial–temporal distribution characteristics of water salinity in groundwater and soil were analyzed in the HID. Differences in groundwater and soil salinity in different land uses and soil types were also compared. Of these, surface runoff and lateral flow salt discharge loading are concentrated in the southwestern portion of the basin, while groundwater salt discharge loading is concentrated in the eastern as well as southwestern portions of the basin. The salt discharge loading from groundwater accounts for about 98.7% of the total salt discharge loading from all hydrological pathways and is the major contributing part of salt discharge from the irrigation area. Soil salinity increases gradually from west to east. Groundwater salinity (2946 mg/L) and soil water electrical conductivity (0.309 dS/m) were minimized in the cropland. Meanwhile, rational allocation of irrigation water can appropriately increase the amount of salt discharge loading. In conclusion, the model could provide a reference for the investigation of soil salinization and water–salt management measures in irrigation areas. [ABSTRACT FROM AUTHOR]

Although liquefaction technology has been extensively applied, plenty of biomass remains tainted with heavy metals (HMs). A meta-analysis of literature published from 2010 to 2023 was conducted to investigate the effects of liquefaction conditions and biomass characteristics on the remaining ratio and chemical speciation of HMs in biochar, aiming to achieve harmless treatment of biomass contaminated with HMs. The results showed that a liquefaction time of 1–3 h led to the largest HMs remaining ratio in biochar, with the mean ranging from 84.09% to 92.76%, compared with liquefaction times of less than 1 h and more than 3 h. Organic and acidic solvents liquefied biochar exhibited the greatest and lowest HMs remaining ratio. The effect of liquefaction temperature on HMs remaining ratio was not significant. The C, H, O, volatile matter, and fixed carbon contents of biomass were negatively correlated with the HMs remaining ratio, and N, S, and ash were positively correlated. In addition, liquefaction significantly transformed the HMs in biochar from bioavailable fractions (F1 and F2) to stable fractions (F3) (P < 0.05) when the temperature was increased to 280–330 ℃, with a liquefaction time of 1–3 h, and organic solvent as the liquefaction solvent. N and ash in biomass were positively correlated with the residue state (F4) of HMs in biochar and negatively correlated with F1 or F2, while H, O, fixed carbon, and volatile matter were negatively correlated with F4 but positively correlated with F3. Machine learning results showed that the contribution of biomass characteristics to HMs remaining ratio was higher than that of liquefaction factor. The most prominent contribution to the chemical speciation changes of HMs was the characteristics of HMs themselves, followed by ash content in biomass, liquefaction time, and C content. The findings of this meta-analysis contribute to factor selection, modification, and application of liquefied biomass to reducing risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic lignin-based hydrochar was synthesized from pulping black liquor. • MLHC 140 demonstrated satisfied Tl(III) removal over a wide pH range (2–9). • Capacity reached 278.9 mg/g and over 90 % of Tl(III) was captured within 15 min. • The mechanisms are mainly surface precipitation and complexation. • Adsorbed MLHC 140 could be recovered easily via a facile external magnet. Waste lignin, such as black liquor (BL) from paper and pulping industries, is an agro-industrial biowaste while its reuse raised global concerns. In this work, a hydrothermal carbonization procedure was employed to convert BL into magnetic lignin-based hydrochar (MLHC) for thallium elimination from wastewater. The results exhibited water purification potential due to a wider working pH window (2–9) with the magnetization intensity of 11.12 emu/g. The maximum adsorption capacity for Tl(III) was 278.9 mg/g, while the contribution of various mechanisms was elucidated with the order: surface precipitation (31.3 %), complexation (20.6 %), physical adsorption (18.2 %), chemical reduction (15.0 %), and ion exchange (14.9 %). This study revealed that hydrothermal treatment could be a potential and promising method to convert waste lignin into magnetic bio-adsorbent to recycle pulping black liquor and apply it for thallium pollution control. [ABSTRACT FROM AUTHOR]

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a new kind of oil cement retarder is prepared by aqueous solution polymerization using acrylamide (AM), 2-methyl-2-acrylic amide propyl sulfonic acid (AMPS) and maleic anhydride (MA) as monomers, and then the polymer PAAM (the acronym of polymer is synthesized by AM, AMPS and MA) was characterized by Fourier transform infrared spectroscopy, the paper also introduced the field performance of this new kind of oil well cement retarder PAAM. Additionally, low field nuclear magnetic resonance (LF-NMR) test technology is employed to test the transverse relaxation time T2 distribution of cement slurry in hydration process, the pure cement slurry C and the cement slurry CHN-1 mixed with polymer PAAM were used as the research object. Finally, combined with the scanning electron microscope (SEM), a further exploration about the retarding mechanism of polymer PAAM was conducted, which shows that mainly reflected in the adsorption, precipitation and complexation effect. [ABSTRACT FROM AUTHOR]

Plants and microbes coexist or compete for survival and their cohesive interactions play a vital role in adapting to metalliferous environments, and can thus be explored to improve microbe-assisted phytoremediation. Plant root exudates are useful nutrient and energy sources for soil microorganisms, with whom they establish intricate communication systems. Some beneficial bacteria and fungi, acting as plant growth promoting microorganisms (PGPMs), may alleviate metal phytotoxicity and stimulate plant growth indirectly via the induction of defense mechanisms against phytopathogens, and/or directly through the solubilization of mineral nutrients (nitrogen, phosphate, potassium, iron, etc.), production of plant growth promoting substances (e.g., phytohormones), and secretion of specific enzymes (e.g., 1-aminocyclopropane-1-carboxylate deaminase). PGPM can also change metal bioavailability in soil through various mechanisms such as acidification, precipitation, chelation, complexation, and redox reactions. This review presents the recent advances and applications made hitherto in understanding the biochemical and molecular mechanisms of plant-microbe interactions and their role in the major processes involved in phytoremediation, such as heavy metal detoxification, mobilization, immobilization, transformation, transport, and distribution. [ABSTRACT FROM AUTHOR]

This work investigated the role of divalent metal cations (Mg2+, Ca2+, and Cd2+) and subsequent precipitation or complexation on decreased contaminant removal by bicarbonate-form anion exchange resin (AER-HCO3) relative to chloride-form AER (AER-Cl). The results showed that the removal of dissolved organic carbon and nitrate was lower for AER-HCO3than AER-Cl, and contaminant removal by AER-HCO3was affected by the presence of metal cation. For instance, magnesium and cadmium exhibited the greatest and least interference, respectively, with contaminant removal by AER-HCO3. The results suggested that precipitation was not the cause of decreased contaminant removal by AER-HCO3, and instead implied that complex formation between the contaminant and divalent metal was responsible for differences in removal by AER [ABSTRACT FROM PUBLISHER]

Purpose: Uranium contamination of subsurface environments was once thought to be an isolated occurrence, mostly at production sites. But recent evidence has shown that the presence of uranium in phosphate fertilizers has caused massive amounts of this element to be released worldwide. Concerns are related to uranium movement to groundwater supplies and its significant toxicological risks to human populations. Information is direly needed on how geochemical processes control uranium transport in the vadose zone. Materials and methods: Laboratory experiments were performed to investigate the effects of the pH of the soil solution on the reactive transport of uranium(VI) in the vadose zone. The uranium solution was prepared by dilution of a 10 M stock solution of uranium perchlorate, (UO(ClO)), with DI water. Two U(VI) solutions were prepared at concentrations of 2 × 10 M at pH 6 and 11 and were percolated under steady-state conditions through columns filled with sand. The convective-dispersion equation (CDE) was used to analyze the tracer and uranium breakthrough curves resulting from the column experiments. The program CXTFIT was used to estimate the transport parameters of equilibrium and nonequilibrium (i.e., two-site and mobile-immobile) models applied to the experimental data. Results and discussion: Comparison of U(VI) breakthrough behavior at pH 6 with that of a nonreactive tracer indicated that U(VI) transport was significantly retarded, and about 52 % of the added U(VI) adsorbed to the quartz sand, likely in the cationic forms UOOH and UO. The adsorption was reversible upon the addition of deionized water. At pH 11, the U(VI) breakthrough curve increased gradually and reached a plateau value C/ C oscillating between 72 and 82 %. Upon reaction, Si was released from the dissolution of quartz sand, which allowed the possible transport of U(VI) following precipitation of a U(VI) containing solid, such as uranyl-silicate minerals, or sorption of U(VI) onto silica colloids. Two-site and mobile-immobile (MIM) models suggested an influence of either rate-limited mass transfer processes or immobile/mobile water partitioning in U(VI) reactive transport. Conclusions: The reactive transport of U(VI) governed by adsorption-desorption processes, precipitation, and complexation reactions in which kinetic behaviors are controlled by pH, solution chemistry, and heterogeneous flow regime impacts the mobility of U(VI). The column transport experiments indicated that under geochemical conditions and vadoze zone processes (preferential flow) that favor the mobility of U(VI), dissolved- and colloidal-phase associations of U(VI) may be transported rapidly and in high concentrations from the soil surface to the groundwater. [ABSTRACT FROM AUTHOR]

Coal gasification slag (CGS) is a carbon-containing solid waste used as an adsorbent to remove low concentrations of mercury from wastewater in a series of batch tests to assess its adsorption properties and safe storage. The results showed that the adsorption of mercury on CGS was a very rapid and efficient process, and adsorption equilibrium was reached in only 10–40 min. A pseudo-second-order kinetics model provided a better fit to the equilibrium data. The adsorption capacity on CGS was just slightly below the value of active carbon. CGS showed the highest mercury removal efficiency at a solution pH of 4. Although the presence of other metal cations and anions affected the adsorption, CGS showed good selectivity for mercury ions. The adsorption of mercury was not affected by low concentrations of Cr3+ or Cu2+. The negative interference of anions on the removal efficiency followed the order: Cl−>H2PO4−>CO32−. The adsorption mechanism related to the functional groups included ion exchange, precipitation, coordination complexation, and surface complexation. Mercury adsorbed on CGS leached very slowly in weakly acidic or basic solution. All results of the study indicate that CGS is an economical and safe adsorbent for potential industrial applications. [ABSTRACT FROM AUTHOR]

• MgAl-Cys-LDH had plentiful groups beneficial for the adsorption of metal ions. • Mechanisms included precipitation, surface complexation and isomorphic substitution. • MgAl-Cys-LDH presented higher removal efficiencies in real water environment. To understand the interaction mechanisms between heavy metals and functional groups modified nanomaterials, the l -cysteine (Cys) intercalated MgAl-layered double hydroxide (MgAl-Cys-LDH) was designed by a facile co-precipitation method and used to remove Cu(II), Pb(II) and Cd(II) in water solutions. The XRD, FTIR, SEM, TEM, EDS and XPS characterization analyses proved the carboxyl, thio and amido groups were successfully introduced into MgAl-LDH. The possible mechanisms were analyzed by the XPS and XRD spectra and involved the precipitation of metal hydroxides or sulfides, surface complexation with abundant surface groups, and the isomorphic substitution of Mg(II). The adsorption kinetics and isotherms data of Cu(II), Pb(II) and Cd(II) on MgAl-Cys-LDH were well described by the pseudo-second-order kinetic equation and the Langmuir model. The influence factors such as initial solution pH of heavy metals, dosage of MgAl-Cys-LDH, adsorption time and various types of water were investigated, and the results suggested that MgAl-Cys-LDH had potential applications in real wastewater treatment containing heavy metals. [ABSTRACT FROM AUTHOR]

Biochar has been widely recognized as an environmentally efficient adsorbent for removal of heavy metals in wastewater. However, inferior adsorption capacity limits its practical application. In this study, a H 3 PO 4 –modified tea branch biochar (PTBB) was firstly prepared through the one step pyrolysis of H 3 PO 4 -pretreated tea branch powder for enhancing removal efficiency of Cd2+ and Pb2+ from aqueous solutions. H 3 PO 4 modification altered the physicochemical properties of pristine biochar. The PTBB exhibited superior adsorption performance. Its maximum adsorption capacities of Cd2+ and Pb2+ were 98.25 mg g−1 and 127.5 mg g−1 at the pH 6 and dosage of 2 g L−1, which was 1.5 and 1.3 folds of the pristine biochar, respectively. Cd2+ and Pb2+ adsorption data by PTBB were well fitted by the Langmuir isothermal and pseudo-second order kinetic models, indicating monolayer chemical adsorption controlled the adsorption process. The adsorption of Cd2+ and Pb2+ by PTBB was a spontaneous endothermic process and less affected by coexisting cations. PTBB demonstrated a greater affinity for Pb2+ as compared with Cd2+ in binary metal systems. Moreover, PTBB could maintain good stability and regeneration properties. The adsorption of Cd2+ and Pb2+ by PTBB was attributed to cation exchange, precipitation, complexation, and π electron interactions. The quantitative analysis indicated that complexation and precipitation were the primary adsorption mechanisms, which accounted for 50.52–50.56% and 36.7–42.18% to total Cd2+ and Pb2+ adsorption for PTBB, respectively. Therefore, PTBB exhibits great potential for application in the remediation of wastewater containing Cd2+ or Pb2+. [Display omitted] • A novel H 3 PO 4 -modified biochar was prepared. • PTBB displayed superior Cd2+ and Pb2+ adsorption capacities. • PTBB enhanced Cd2+ and Pb2+ adsorption capacity by mineral precipitation and complexation. [ABSTRACT FROM AUTHOR]

The remediation of Cd-polluted sediment in coastal rivers is essential because of its potential hazards to river and marine ecosystems. Herein, a co-pyrolysis product of contaminated dredged sediment (S@BC) was innovatively applied to cap and immobilize Cd-contaminated sediment in coastal rivers in situ, and their remediation efficiencies, mechanisms, and microbial responses were explored based on a 360 d incubation experiment. The results showed that although S@BC immobilization and capping restrained sediment Cd release to the overlying water, S@BC capping presented a high inhibitory efficiency (66.0% vs. 95.3% at 360 d). Fraction analysis indicated that labile Cd was partially transformed to stable fraction after remediation, with decreases of 0.5%− 32.7% in the acid-soluble fraction and increases of 5.0%− 182.8% in the residual fraction. S@BC immobilization and capping had minor influences on the sediment bacterial community structure compared to the control. S@BC could directly adsorb sediment mobile Cd (precipitation and complexation) to inhibit Cd release and change sediment properties (e.g., pH and cation exchange capacity) to indirectly reduce Cd release. Particularly, S@BC capping also promoted Cd stabilization by enhancing the sediment sulfate reduction process. Comparatively, S@BC capping was a priority approach for Cd-polluted sediment remediation. This study provides new insights into the remediation of Cd-contaminated sediments in coastal rivers. [Display omitted] • Co-pyrolysis product of dredged sediment (S@BC) reduced sedimental Cd release. • S@BC capping could more effectively inhibit Cd release from sediments. • S@BC immobilization and capping posed no adverse effect on sediment bacterial community. • S@BC restrained Cd release by direct adsorption and indirectly altering sediment properties. • S@BC capping was a more promising method for Cd polluted sediment remediation. [ABSTRACT FROM AUTHOR]

The adsorption characteristics and mechanism of Cd2+ on microbial inoculant (MI) mainly composed of Bacillus subtilis , Bacillus thuringiensis and Bacillus amyloliquefaciens , and its potential for remediation Cd polluted soils through batch adsorption and soil incubation experiments. It was found that the Freundlich isotherm model and the pseudo–second–order kinetics were more in line with the adsorption processes of Cd2+. The maximum adsorption capacity predicted by Langmuir isotherm model suggested that of MI was 57.38 mg g−1. Scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS) images exhibited the surface structure of MI was damaged to varying degrees after adsorption, and Cd element was distributed on the surface of MI through ion exchange. X–ray diffraction (XRD) results showed that CdCO 3 was formed on the surface of MI. Moreover, the functional groups (–OH, C–H, and –NH) involved in the adsorption of Cd2+ through fourier transform infrared spectroscopy (FTIR). After applying MI to Cd–contaminated soil, it was found that soil pH, conductivity (EC) and soil organic matter (SOM) increased by 0.84 %–2.43 %, 31.6 %–241.48 %, and 8.11 %–24.1 %, respectively, when compared with the control treatments. The content of DTPA–Cd in the soils was significantly (P < 0.05) reduced by 15.48 %–29.68 % in contrast with CK, and the Cd speciation was transformed into a more stable residual fraction. The activities of urease, phosphatase and sucrose were increased by 3.5 %–45.18 %, 57.00 %–134.18 % and 52.51 %–70.52 %, respectively, compared with CK. Therefore, MI could be used as an ecofriendly and sustainable material for bioremediation of Cd–contaminated soils. [Display omitted] • MI exhibited effectively remediate Cd-contaminated water and soil. • MI can immobilize Cd through ion exchange, precipitation and complexation. • MI reduced the availability of soil Cd and improved soil chemical properties. [ABSTRACT FROM AUTHOR]

Using a co-impregnation technique, Sr-doped hydroxyapatite (HAP-Sr) loaded in magnetic mesoporous carbon (MMC) was successfully prepared. Extensive characterization was performed on MMC, HAP-Sr, and the composite (MMC/HAP-Sr) to determine their properties. In addition, their U(VI) adsorption capacities were thoroughly investigated. The key factors influencing U(VI) adsorption were investigated. In accordance with the results, the equilibrium of MMC/HAP-Sr on U(VI) was reached within 10 min. In addition, the substance's theoretical saturation capacity was 1229.9 mg·g−1. XRD and XPS tests showed the sorption of U(VI) by MMC/HAP-Sr is mainly via precipitation and complexation with hydroxyl (-OH) on the surface. Thus, MMC/HAP-Sr is an excellent adsorbent for the treatment of radioactive wastewater containing U(VI). [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Converting limestone sludge waste into hydroxyapatite rod-shaped particles by hydrothermal method. • The obtained materials were found to be effective adsorbents for Pb2+. • Preparing a novel sorbent with high adsorption capacity of 476.19 mg/g. • This provides a new avenue to address wastewater treatment and limestone sludge. This paper reports on the recycling of the Ca2+ ion-rich filtrate of limestone sludge for use as a raw material in the hydrothermal synthesis of hydroxyapatite (HAp) applicable to the removal of Pb2+ ions from aqueous solutions. Samples of HAp (eco-HAp) were prepared using a range of Ca/P molar ratios (Ca/P MRs) (1, 1.67, 2.33 and 3) and hydrothermal temperatures (393–453 K). Fourier transform infrared spectroscopy revealed the presence of O–H groups and PO 4 3–(ν1) groups (indicative of HAp). Transmission electron microscopy revealed the presence of elliptical surface microstructures. Solid-state nuclear magnetic resonance (NMR) spectroscopy revealed single crystal sites of inorganic phosphorus (31P) and hydroxyls (1H). The adsorption capacity of eco-HAp samples reached 476.19 mg/g within 20 min. The results of adsorption kinetics were characteristic of pseudo-second-order kinetics. Langmuir adsorption isotherms revealed that the Pb2+ adsorption capacity of ecoHAp was 277.77 mg/g, which can be attributed to a synergistic mechanism involving ion exchange, chemical precipitation, surface complexation, and dissolution/precipitation. Taken together, these results demonstrate the potential of eco-HAp as an adsorbent material with broad industrial applicability for the removal of heavy metals from aqueous solutions. [ABSTRACT FROM AUTHOR]

Mining-related copper (Cu) and cadmium (Cd) contamination poses a serious threat to agricultural security and human health. To lessen the environmental danger of Cu and Cd in soil and improve soil environmental quality, we designed and prepared a soil amendment that could efficiently immobilize Cu and Cd in farmland and improve soil fertility. Sugarcane bagasse biochar was selected as the substrate, and nitrogen and magnesium oxide nanomaterials were doped on the biochar surface (denoted as Mg-N/BC) by a simple calcination method. After 90 days of incubation, the immobilization efficiencies of Cu and Cd were 64.3% and 45.2%, respectively, when the dosage of Mg-N/BC was 1%. Mg-N/BC increased soil pH, cation exchange capacity (CEC), and soil organic matter (OM), and facilitated the conversion of Cu and Cd ions from acid-soluble to more stable forms through ion exchange, precipitation, and complexation. Moreover, the urease and sucrase activities of the remediated soil increased by 60.14% and 301.2%, separately, reflecting the decreased toxicity of heavy metals to microorganisms. More importantly, Mg-N/BC immobilized soil heavy metals while supplementing nitrogen fertilizer in the soil, effectively promoting plant growth. This study provides a new strategy for simultaneous remediation of heavy metal-contaminated soil and improving soil fertility. [Display omitted] • A novel amendment for simultaneous soil heavy metals immobilization and N supply was developed. • Cu and Cd ions from acid-soluble to more stable forms. • Mg-N/BC ameliorated the soil environment. • Pot test confirmed Mg-N/BC is a promising amendment for agricultural soil remediation. [ABSTRACT FROM AUTHOR]