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Montmorillonite (Mt) is one of the eco-friendly and low-cost nano-adsorbents for water and wastewater treatment. Interactions of Mt. with various modifiers such as surfactants and polymers make it an ideal adsorbent with good selectivity for the removal of phenols, heavy metals and drug residues from water and wastewater. Surface modification can improve the adsorption potential of Mt. due to increasing the number of adsorption sites and functional groups to remove a wide variety of contaminants. This paper shows a general overview of the structure, adsorptive characteristics, and applications of Mt. and modified Mt. (m-Mt). Also, recent progress made in using of natural and modified bentonite and Mt. for removing phenols, heavy metals and pharmaceuticals from water and wastewater are explained. Furthermore, it discusses the strategies used to increase the adsorption capacity of Mt. by surface modification with cationic surfactants, acids, and polymers. This article delivers an exploration of the current uses of bentonite and Mt. for water and wastewater treatment and encouraging results obtained in this review could aid in the application Mt. and m-Mt for the recovery of high added value compounds and removal of contaminants from aquatic systems., Competing Interests: Declaration of competing interest All authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, pyrolysis was performed at different times to convert Oedogonium biomass into biochar. The physicochemical properties show that the pyrolysis time significantly impacts structural and morphological changes in biochar samples. The influence of pyrolysis time on the removal of multiple heavy metals was investigated. Owing to the presence of abundant functional groups, inorganic minerals and porous nature, biochar obtained from a 40 min pyrolysis time showed higher removal efficiency of heavy metals compared to biochars pyrolyzed at 20 mins and 60 mins even with higher concentrations of metal ions. The maximum adsorption capacity was observed 9.33, 10.74, 322.58, 13.70 and 9.11 mg/g with the biochar prepared at the pyrolysis time of 40 mins for Co, Ni, Cu, Zn and Cd, respectively. The adsorption isotherm is well fitted with the Langmuir adsorption model for heavy metals adsorption, and the kinetic study is well-defined by a pseudo second-order model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Hydrogel-based sorbents show promise in the removal of toxic metals from water. However, optimizing their performance through conventional trial-and-error methods is both costly and challenging due to the inherent high-dimensional parameter space associated with complex condition combinations. In this study, machine learning (ML) was employed to uncover the relationship between the fabrication condition of hydrogel sorbent and their efficiency in removing toxic metals. The developed XGBoost models demonstrated exceptional accuracy in predicting hydrogel adsorption coefficients (K d ) based on synthesis materials and fabrication conditions. Key factors such as reaction temperature (50-70 °C), time (5-72 h), initiator ((NH 4 ) 2 S 2 O 8 : 2.3-10.3 mol%), and crosslinker (Methylene-Bis-Acrylamide: 1.5-4.3 mol%) significantly influenced K d . Subsequently, ten hydrogels were fabricated utilizing these optimized feature combinations based on Bayesian optimization, exhibiting superior toxic metal adsorption capabilities that surpassed existing limits (logK d (Cu): increased from 2.70 to 3.06; logK d (Pb): increased from 2.76 to 3.37). Within these determined combinations, the error range (0.025-0.172) between model predictions and experimental validations for logK d (Pb) indicated negligible disparity. Our research outcomes not only offer valuable insights but also provide practical guidance, highlighting the potential for custom-tailored hydrogel designs to combat specific contaminants, courtesy of ML-based Bayesian optimization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In current study, a new adsorbent based on aminated phenol-formaldehyde composite was prepared using chitosan as modifier. Various techniques were adopted to characterize the morphology and structure of the prepared adsorbent. Due to the abundant amino groups, the obtained adsorbent presented satisfactory adsorption performance towards fluoroquinolones (FQs) and heavy metal ions (including Cu 2+ , Cd 2+ and Pb 2+ ) by means of multiple forces including electrostatic, H-bonding, π-π stacking interactions (for FQs) and chelating force (for heavy metal ions). Studies about the adsorption kinetics, isotherm and thermodynamics were performed to inspect the adsorption behaviors of studied FQs and heavy metal ions on the new adsorbent. After optimizing the adsorption parameters, the obtained adsorbent were employed to remove FQs, Cu 2+ , Cd 2+ and Pb 2+ in various environmental waters. The removal rates for FQs and heavy metal ions were 91.8-98.6 % and 94.4-98.5 %, respectively, which were significantly higher than that obtained on unmodified phenol-formaldehyde resin (20.7-49.0 % for FQs and 35.1-43.0 % for heavy metal ions). At the same time, the adsorbent exhibited good preparation repeatability in different batches, acceptable stability and reusability. The current study well demonstrated the potential application of the new adsorbent in the simultaneous removal of organic and inorganic pollutants from aqueous waters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

At present, many oil-water separation membranes are being developed to purify oily wastewater. However, oily wastewater often contains heavy metal, which are often difficult to dispose during separation. Furthermore, most of the oil-water separation membranes cannot be degraded after scrap, producing pollution to environment. Herein, the polyvinyl alcohol/chitosan@carnauba wax (PCGCW) membrane with heavy metal adsorption and biodegradation performance was acquired by electrospinning and spraying process. The acquired PCGCW membrane had excellent mechanical properties after crosslinking glutaraldehyde (GA). Furthermore, the composite membrane had excellent superhydrophobic property (WCA = 154°) with a rolling angle of 2°, due to the introduction of carnauba wax. Exhilaratingly, for emulsions with surfactant, it had a high separation flux with 19,217 L·m -2 ·h -1 ·bar -1 and splendid an oil purity over 99.9 %. Besides, the efficiency of oil purity and separation flux remained stable even after 10 separations. In addition, the PCGCW membrane had the ability to adsorb heavy metals with adsorption capacity of 51-106 mg/g for Cu 2+ , Fe 3+ , Co 2+ ions. Foremost, the superhydrophobic PCGCW membrane was biodegradable, with degrading 29.76 % within 40 days. The prepared composite membrane had the advantages of low cost, high separation flux, great repeatability, adsorbable heavy metals and degradability, which had a vast application prospect., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Grafted chitosan materials show the characteristics of high stability, easy separation and recovery, and good heavy metal adsorption capacity, and have received much attention in the adsorption process. Therefore, in this work, novel grafted chitosan-based adsorbent CS-EHBSB@F-AE was prepared by a one-pot reaction of chitosan (CS), 3-ethoxy-4-hydroxybenzaldehyde (EHB), formaldehyde (F) and aminoethanol (F). The microstructure and morphology of the as-prepared composite CS-EHBSB@F-AE were characterized by FT-IR, TGA, DSC, FE-SEM, and BET analyses. The adsorption performance of the as-prepared CS-EHBSB@F-AE composite on Pb(II), Hg(II), and Cu(II) ions from aqueous was investigated using batch experiment and the effects of the initial pH of the solution, contact time, and initial metal ions concentration and temperature on the adsorption efficiency were investigated and discussed. At the best conditions, CS-EHBSB@F-AE exhibited remarkable adsorption capacity of 246.7 mg/g, 203.9 mg/g, and 234.4 mg/g in absorbing Pb(II), Hg(II), and Cu(II), respectively. The adsorption equilibrium and the kinetic studies confirmed that the ions adsorption process fits well with the Langmuir isotherm and pseudo-second-order (PSO) models. Additionally, the adsorption efficiency of Pb(II), Hg(II), and Cu(II) metal ions by the composite CS-EHBSB@F-AE was reduced by increasing the temperature from 298 K to 318 K. In addition, after the sixth ads/des cycles, the as-prepared adsorbent still exhibited high removal efficiency with a decrease in adsorption efficiency of Pb(II) (5.53 %), Hg(II) (15.43 %) and Cu(II) (8.27 %). Finally, we proposed that the ions adsorption by CS-EHBSB@F-AE has happened using the coordination of active groups containing nitrogen and oxygen atoms on the surface of the adsorbent with the Pb(II), Hg(II), and Cu(II) metal ions., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Herein, a novel acylhydrazone biosorbent (GSL) with abundant three-dimensional porous structure was successfully prepared by using low-cost starch as raw material for water pollution remediation applications. Various analytical techniques were applied to characterize the morphological structure and chemical composition. Interestingly, the adsorption efficiency of the adsorbent towards Malachite green (MG), Safranin O (SO), Cu 2+ , and sulfide in the static adsorption experiment was extremely high due to presence of ample functional groups. Additionally, the adsorption isotherm and kinetic experiments revealed that the adsorption processes were based on monolayer chemisorption. The maximum sorption amounts were 2237.4961 mg/g for SO, 2101.6610 mg/g for MG, 410.7019 mg/g for Cu 2+ , and 483.0194 mg/g for sulfides at 298.15 k. The thermodynamic analysis also demonstrated that all adsorption processes were spontaneous heat processes. The adsorption mechanism was analyzed by FTIR, SEM-EDAX and XPS. The adsorption of SO onto GSL reached 1025.8617 mg/g in continuous adsorption experiments, and the experimental data were fitted through the Thomas model and Yoon-Nelson model. Furthermore, the GSL showed good reusability and salt resistance. Importantly, starch-based acylhydrazone as the adsorbent for the simultaneous removal of hazardous dyes, heavy metal ions and sulfhides has not yet been seen reported., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The environmental pollution caused by heavy metal ions has become a serious global environmental issue. Heavy metal contaminants released from industrial effluents, agricultural runoff, and human activities, can enter into water resources. The toxicity of these heavy metal ions even at trace concentrations presents a substantial hazard to both aquatic systems and human well-being. The membrane separation processes have become more promising sustainable techniques for the separation of metal ions from the effluent. The research efforts have been concentrated on improving the synthesis of membranes and membrane materials to facilitate the sustainable separation of heavy metals. The application of chitosan in the fabrication of membranes is getting more attention. Chitosan, a natural polysaccharide derived from chitin, is abundant in nature and has active hydroxyl and amino groups suitable for the separation of heavy metal ions. It exhibits excellent chelating tendency, biocompatibility, and biodegradability. The functionalization of chitosan to improve its mechanical strength, chemical stability, and antifouling properties has become an ongoing area of research. This review examines the synthesis and efficient applications of chitosan blended membranes. The review concludes by outlining the current challenges and proposing future research prospects to enhance the applicability of chitosan-blended membranes in environmental remediation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microalgal biomass has shown inspiring potential for the heavy metal removal from wastewater, and forming microalgal biofilm is one of the sustainable methods for the microalgal biomass production. Here we report the formation of microalgal biofilm by accelerated colonization of typical algae Chlorella on thermal sprayed aluminum (Al) coatings with biologically modified surfaces. Micro-patterning surface treatment of the Al coatings promotes the attachment of Chlorella from 6.31 % to 17.51 %. Further enhanced algae attachment is achieved through liquid flame spraying a bioactive crushed oyster shell-hydroxyapatite (CaCO 3 -HA) composite top layer on the micropatterned coating, reaching 46.03-49.62 % of Chlorella attachment ratio after soaking in Chlorella suspension for 5 days. The rapidly formed microalgal biofilm shows an adsorption ratio of 95.43 % and 85.23 % for low concentration Zn 2+ and Cu 2+ in artificial seawater respectively within 3 days. Quick interaction has been realized between heavy metal ions and the negatively-charged extracellular polymeric substances (EPS) matrix existing in the biofilm. Fourier transform infrared spectroscopy (FTIR) results indicate that both carboxyl and phosphoryl groups of biofilms are crucial in the adsorption of Cu 2+ and the adsorption of Zn 2+ is due to the hydroxyl and phosphate groups. Meanwhile, the biofilm could act as a barrier to protect Chlorella against the attack of the heavy metal ions with relatively low concentrations in aqueous solution. The route of quick cultivating microalgal biofilm on marine structures through constructing biological layer on their surfaces would give insight into developing new techniques for removing low concentration heavy metal ions from water for environmental bioremediation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The excessive accumulation of heavy metals has adverse effects on the human body. Here, magnetic iron oxide-impregnated carboxymethyl-β-cyclodextrin was synthesized. The synthesized material was employed as a magnetic solid-phase extracting adsorbent for specific heavy metals like lead (Pb), nickel (Ni), copper (Cu), and cobalt (Co). Characterization was performed by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier-transform infrared spectroscopy. The analytical merits, like detection limits (Pb: 1.38 ng/mL, Ni: 0.5 ng/mL, Co: 0.14 ng/mL, and Cu: 0.55 ng/mL) and quantification limits (Pb: 4.14 ng/mL, Ni: 1.62 ng/mL, Co: 1.85 ng/mL, and Cu: 1.82 ng/mL) were calculated. Similarly, the preconcentration and enhancement factors (15) and relative standard deviation (Pb: 3.5, Ni: 0.92, Co: 2.7, and Cu: 1.5) were also calculated. The interfering study shows that the method is highly selective. For validation, it was applied to certified reference materials such as the Institute of Nuclear Chemistry and Technology ornamental Basma tobacco leaves and trace metal double addition 63.4 environmental water with good percent recovery values (92%-99%). Real water and food samples were also used with satisfactory (90%-99%) recovery results., (© 2024 Wiley‐VCH GmbH.)

The dual-frequency ultrasound-assisted enzymatic digestion (DUED) technique was developed for synchronous green extraction of five heavy metal ions in root vegetables. The combination of α-amylase, cellulase, and papain showed significant advantageous in extracting heavy metal ions. Under optimized dual-frequency ultrasonic conditions, the extraction rates of Cr, As, Cd, Pb, and Hg in carrots reached 99.04%, 105.88%, 104.65%, 104.10%, and 103.13% respectively. And the extraction process is highly efficient, completing in just 15 min. Compared to conventional microwave-assisted acid hydrolysis method, this technique eliminates the need for high-temperature concentrated acid, enhancing its environmental sustainability while maintaining mild reaction conditions, making it ideal for biosensors application. Additionally, simultaneous extraction and detection of four heavy metals in lotus roots were successfully achieved by using DUED and a fluorescent paper-based microfluidic chip. The obtained results are consistent with those obtained using conventional methods., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

High adsorption capacity, high adsorption rate and reusable adsorbents are urgent needed for removing heavy metals from wastewater. In this study, porous sodium alginate/cellulose nanofiber (SA/CNF) composite hydrogel microspheres were prepared by combining sodium alginate with cellulose nanofibers by microfluidics technology and adding polyethylene glycol (PEG) as pore making agent. The SA/CNF composite hydrogel microspheres could efficiently adsorb heavy metals (Pb 2+ , Cu 2+ and Cd 2+ ) in wastewater. The influencing factors of adsorption process, including pH, temperature, initial concentration, coexisting ions and aquatic environments, were systematically discussed. The adsorption process was more consistent with Langmuir isotherm model and pseudo-second-order model in batch system, indicating the adsorption process was mainly chemical adsorption. The adsorption capacity to Pb 2+ obtained by Langmuir model was as high as 544.66 mg/g at 20 °C. Fixed-bed column adsorption experiments demonstrated the excellent performance of the as-prepared SA/CNF microspheres for treatment of the flowing wastewater in a column system. Overall, a highly practical adsorption process based on hydrogel adsorbents was developed for the removal of heavy metals from actual wastewater., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Emerging contaminants, including per- and polyfluoroalkyl substances and heavy metals, are threatening the health of humans and ecosystems. Their removal from the environment remains challenging. Here, we designed silk fibroin-cellulose nanocrystal (silk-CNC) nanofibrillar and nanoporous membranes for emerging contaminant remediation. The protein-polysaccharide nanofibrils were fabricated by templating the assembly of silk fibroin using CNCs. Silk fibroin polymorphic nature combined with surface charge modulation of CNCs produced cationic silk-CNC(+) and anionic silk-CNC(-) nanofibrils that can target a broad spectrum of contaminants. Silk-CNC(+) nanofibrils and membranes exhibited antimicrobial properties and captured both short-chain heptafluorobutyric acid, perfluorobutanesulfonic acid, and long-chain perfluorooctanoic acid by virtue of hydrophobic attraction from β-sheeted silk fibroin and electrostatic interactions with CNC(+). Silk-CNC(-) provided the opportunity to target cations such as heavy metal cocontaminants. The nanofabrication of biopolymer-based membranes combines high performance with environmentally benign and cost-effective removal of emerging contaminants for water purification, wastewater treatment, and remediation.

Compounds functionalized with hydroxyl and amino groups were found to have good potential for the adsorption of different ions. In this work, a new system of cellulosic chains was amended with amine substitutions and bonded to a magnetic core of NiFe 2 O 4 @SiO 2 to form NiFe 2 O 4 @SiO 2 -cellulose-NH 2 system. The prepared sample showed suitable magnetic separation and was characterized via XRD, FT-IR, SEM, EDS, and TGA-DTA analyses. The adsorption potential of NiFe 2 O 4 @SiO 2 -cellulose-NH 2 system has been investigated on the heavy metals (Cd, Ni, and Pb) removal from a synthetic wastewater environment. The results show that the magnetic property created by the magnetic core increased the recycling potential of the adsorbent and the magnetic core has a positive effect on the absorption potential of the polymer. The adsorption removal of Cd(II), Ni(II), and Pb(II) ions was studied using NiFe 2 O 4 @SiO 2 -cellulose-NH 2 systems in different pH, temperatures, metal ion concentrations, and adsorbent dosages. The maximum adsorption capacities of single heavy metal ions were obtained as 406.44 mg/g (for Cd(II) ions), 411.63 mg/g (for Ni(II) ions), and 414.68 mg/g (for Pb(II) ions) under optimized conditions as pH = 6.5, ion concentration: 500 mg/L, adsorbent dosage: 1.2 g/L and room temperature., Competing Interests: Declaration of competing interest The authors declare that they have no interest to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Ladle slag, a by-product of steelmaking, presents a valuable strategy for waste reduction and valorization in wastewater treatment. This work demonstrates the successful simultaneous removal of Al(III), B(III), Ba(II), Cr(III), Mg(II), Sr(II), Pb(II), and Zn(II), from electroplating wastewater by ladle slag. First, Cr(III) and Pb(II) removals were evaluated in single synthetic systems by analyzing the influence of pH, temperature, and ladle slag dosage. Competitive removal was observed in binary batch experiments of Cr(III) - Pb(II), achieving 88% and 96% removal, respectively, with fast kinetics following a pseudo-second-order model. The findings of XRD, SEM, EDX, and FTIR of the slag after removal helped to elucidate the synergic removal mechanism involving ladle slag dissolution, precipitation, ion exchange, and adsorption in a tight relationship with the solution pH. Lastly, ladle slag was tested in real electroplating wastewater with the aforementioned ions at concentrations ranging from <1 to 1700 mg/L. The removal was performed in two steps, the first attained the following efficiencies: 73% for Al(III), 88% for B(III), 98% for Ba(II), 80% for Cr(III), 82% for Mg(II), 99% for Pb(II), 88% for Sr(II), and 88% for Zn(II). Visual MINTEQ simulation was utilized to identify the different species of ions present during the removal process. Furthermore, the leaching tests indicated a minimal environmental risk of secondary pollution in its application. The results promote an effective and sustainable approach to wastewater treatment within the circular economy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Access to clean water, hygiene, and sanitation is becoming an increasingly pressing global demand, particularly owing to rapid population growth and urbanization. Phytoremediation utilizes a highly conserved phytochelatin in plants, which captures hazardous heavy metal ions from aquatic environments and sequesters them in vacuoles. Herein, we report the design of phytochelatin-inspired copolymers containing carboxylate and thiolate moieties. Titration calorimetry results indicate that the coexistence of both moieties is essential for the excellent Cd 2+ ion-capturing capacity of the copolymers. The obtained dissociation constant, K D  ~ 1 nM for Cd 2+ ion, is four-to-five orders of magnitude higher than that for peptides mimicking the sequence of endogenous phytochelatin. Furthermore, infrared and nuclear magnetic resonance spectroscopy results unravel the mechanism underlying complex formation at the molecular level. The grafting of 0.1 g bio-inspired copolymers onto silica microparticles and cellulose membranes helps concentrate the copolymer-coated microparticles in ≈3 mL volume to remove Cd 2+ ions from 0.3 L of water within 1 h to the drinking water level (<0.03 µM). The obtained results suggest that hyperconfinement of bio-inspired polymers in flow-through systems can be applied for the highly selective removal of harmful contaminants from the environmental water., (© 2024. The Author(s).)

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to contaminated anaerobic environments. The research focused on elucidating the physiological characteristics and optimal growth conditions of SRB, particularly in relation to the pH level and temperature. The experimental findings reveal that the SRB exhibited a sulfate removal rate of 88.86% at an optimal temperature of 30 °C. Additionally, SRB gel particles were formulated using sodium alginate (SA) and carboxymethyl cellulose (CMC), and their performance was assessed under specific conditions (pH = 6, C/S = 1.5, T = 30 °C, CMC = 4.5%, BSNa = 0.4 mol/L, and cross-linking time = 9 h). Under these conditions, the SRB gel particles demonstrated an enhanced sulfate removal efficiency of 91.6%. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) provided further insights into the stability and properties of the SRB gel spheres. The findings underscore the potential of SRB-based bioremediation as a sustainable and efficient method for AMD treatment, offering a novel and environmentally friendly solution to mitigating the adverse effects of environmental contamination.

To achieve the objective of "waste control by waste", in this study, a green aerogel adsorbent comprised of pomelo-peel cellulose and sodium alginate (PCC/SA) was prepared through dual-network crosslinking. The resulting 3D hierarchical porous structured PCC/SA aerogel exhibited good structural stability, and kept the morphological integrity during 10 days in a wide pH range (2-10), suggesting its potential for recycling in diverse complex environments. Besides, the superior adsorption capacities for methylene blue (MB) and Cu(II) were observed, with the q m values and adsorption equilibrium times were recorded to be 1299.59 mg/g (300 min) and 287.55 mg/g (120 min), correspondingly. Furthermore, the favorable reusability of the PCC/SA aerogel was also demonstrated, with the removal efficiency for MB remaining almost unchanged (about 94 %) after 10 adsorption-desorption cycles, while there was a slight reduction for Cu(II) from 85.28 % to 72.47 %. XPS and FTIR analysis revealed that electrostatic attraction, hydrogen bonding, cation exchange and coordination were the major adsorption mechanisms. Importantly, the PCC/SA aerogel can be naturally degraded in soil within 10 weeks. Therefore, the as-prepared aerogel bead derived from pomelo peel shows great promise as an adsorbent for wastewater treatment containing dye and heavy metal ions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Developing eco-friendly, cost-effective, and efficient methods for treating water pollutants has become paramount in recent years. Biopolyelectrolytes (BPEs), comprising natural polymers like chitosan, alginate, and cellulose, have emerged as versatile tools in this pursuit. This review offers a comprehensive exploration of the diverse roles of BPEs in combating water contamination, spanning coagulation-flocculation, adsorption, and filtration membrane techniques. With ionizable functional groups, BPEs exhibit promise in removing heavy metals, dyes, and various pollutants. Studies showcase the efficacy of chitosan, alginate, and pectin in achieving notable removal rates. BPEs efficiently adsorb heavy metal ions, dyes, and pesticides, leveraging robust adsorption capacity and exceptional mechanical properties. Furthermore, BPEs play a pivotal role in filtration membrane techniques, offering efficient separation systems with high removal rates and low energy consumption. Despite challenges related to production costs and property variability, their environmentally friendly, biodegradable, renewable, and recyclable nature positions BPEs as compelling candidates for sustainable water treatment technologies. This review delves deeper into BPEs' modification and integration with other materials; these natural polymers hold substantial promise in revolutionizing the landscape of water treatment technologies, offering eco-conscious solutions to address the pressing global issue of water pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Water pollution is one of serious environmental issues due to the rapid development of industrial and agricultural sectors, and clean water resources have been receiving increasing attention. Recently, more and more studies have witnessed significant development of catalysts (metal oxides, metal sulfides, metal-organic frameworks, zero-valent metal, etc.) for wastewater treatment and water purification. Sustainable and clean catalysts immobilized into chitosan-based materials (Cat@CSbMs) are considered one of the most appealing subclasses of functional materials due to their high catalytic activity, high adsorption capacities, non-toxicity and relative stability. This review provides a summary of various upgrading renewable Cat@CSbMs (such as cocatalyst, photocatalyst, and Fenton-like reagent, etc.). As for engineering applications, further researches of Cat@CSbMs should focus on treating complex wastewater containing both heavy metals and organic pollutants, as well as developing continuous flow treatment methods for industrial wastewater using Cat@CSbMs. In conclusion, this review abridges the gap between different approaches for upgrading renewable and clean Cat@CSbMs and their future applications. This will contribute to the development of cleaner and sustainable Cat@CSbMs for wastewater treatment and water purification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Chromatography is a technique of separation based on adsorption and/or interaction of target molecules with stationary phases. Herein, we report the design and fabrication of BTDA@SiO 2 core-shell microspheres as a new class of stationary phase and demonstrate its impressive performance for chromatographic separations. The silica microspheres of BTDA@SiO 2 were synthesized by in situ method with 1,3,5-benzenetricarboxaldehyde and 3,5-diaminobenzoic to separate peptides and proteins on high-performance liquid chromatography. The BTDA@SiO 2 core-shell structure has a high specific surface area and retention factor of 4.27 and 8.31 for anionic and cationic peptides, respectively. The separation factor and resolution were high as well. A typical chromatogram illustrated nearly baseline resolution of the two peptides in less than 3 min. The BTDA@SiO 2 was also highly stable in the pH range of 1 to 14. Furthermore, the prepared BTDA@SiO 2 core-shell material not only be used for chromatographic separation but also as heavy metal removal from water. Using a BTDA@SiO 2 , we also achieved a lysozyme enrichment with a maximum saturated adsorption capacity reaching 714 mg/g. In summary, BTDA@SiO 2 has great application prospects and significance in separation and purification systems., (© 2024 Wiley‐VCH GmbH.)

Due to the high concentration of various toxic and dangerous pollutants, industrial effluents have imposed increasing threats. Among the various processes for wastewater treatment, adsorption is widely used due to its simplicity, good treatment efficiency, availability of a wide range of adsorbents, and cost-effectiveness. Chitosan (CS) has received great attention as a pollutant adsorbent due to its low cost and many -OH and -NH 2 functional groups that can bind heavy metal ions. However, weaknesses such as sensitivity to pH, low thermal stability and low mechanical strength, limit the application of CS in wastewater treatment. The modification of these functional groups can improve its performance via cross-linking and grafting agents. The porosity and specific surface area of CS in powder form are not ideal, so physical modification of CS via integration with other materials (e.g., metal oxide, zeolite, clay, etc.) leads to the creation of composite materials with improved absorption performance. This review provides reports on the application of CS and its nanocomposites (NCs) for the removal of various heavy metal ions. Synthesis strategy, adsorption mechanism and influencing factors on sorbents for heavy metals are discussed in detail., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Multilayered graphene oxide (GO) membranes are promising to be widely applied to purify water effectively. However, the performance of most membranes prepared at present is not ideal, which may be related to the pore diameter of the substrate (determining the real loading amount of GO) and the size of the GO nanosheets (determining the number of channels on the unit area), which has not been fully studied. In this study, a rotating dip-coating reactor were firstly developed to ensure the uniform deposition of reactants on the surface of the substrate. Then, the preparation method for the membrane was improved. Microfiltration membranes were used as the supporting substrate, polydopamine was deposited as the adhesive layer, ethylenediamine was used to restrict the layer spacing to strengthen the size exclusion effect, and positively charged polyethyleneimine (PEI) was used to strengthen the Donnan effect. Finally, the effects of the pore size of the substrate and the size of the GO nanosheets on the membrane performance were investigated. Compared with the substrates with a pore size of 0.22 μm in most literatures, substrates of 0.1 μm can retain more small GO (SGO) nanosheets, thereby improving the performance. The performance of the SGO membrane was much better than that of the large-sized GO membrane. With a water permeability of no less than 7.9 L/(m 2 ·h·bar), rejection rates for Pb 2+ and Cd 2+ of the SGO membrane could reach more than 97%. These findings are constructive to separate heavy metals from water effectively.

The presence of heavy metals in water pose a serious threat to both public and environmental health. However, the advances in the application of low cost biochar based adsorbent synthesize from various feedstocks plays an effective role in the of removal heavy metals from water. This study implies the introduction of novel method of converting food waste (FW) to biochar through pyrolysis, examine its physiochemical characteristics, and investigate its adsorption potential for the removal of heavy metals from water. The results revealed that biochar yield decreased from 18.4 % to 14.31 % with increase in pyrolysis temperature from 350 to 550 °C. Likewise, increase in the pyrolysis temperature also resulted in the increase in the ash content from 39.87 % to 42.05 % thus transforming the biochar into alkaline nature (pH 10.17). The structural and chemical compositions of biochar produced at various temperatures (350, 450, and 550 °C) showed a wide range of mineralogical composition, and changes in the concentration of surface functional groups. Similarly, the adsorption potential showed that all the produced biochar effectively removed the selected heavy metals from wastewater. However a slightly high removal capacity was observed for biochar produced at 550 °C that was credited to the alkaline nature, negatively charged biochar active sites due to O-containing functional groups and swelling behavior. The results also showed that the maximum adsorption was recorded at pH 8 at adsorbent dose of 2.5 g L -1 with the contact time of 120 min. To express the adsorption equilibrium, the results were subjected to Langmuir and Freundlich isotherms and correlation coefficient implies that the adsorption process follows the Freundlich adsorption isotherm. The findings of this study suggest the suitability of the novel FW derived biochar as an effective and low cost adsorbent for the removal of heavy metals form wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The discharge of heavy metal ions from industrial wastewater into natural water bodies is a consequence of global industrialisation. Due to their high toxicity and resistance to degradation, these heavy metal ions pose a substantial threat to human health as they accumulate and amplify. Alginate-based composite gels exhibit good adsorption and mechanical properties, excellent biodegradability, and non-toxicity, making them environmentally friendly heavy metal ion adsorbents for water with promising development prospects. This paper introduces the basic properties, cross-linking methods, synthetic approaches, modification methods, and manufacturing techniques of alginate-based composite gels. The adsorption properties and mechanical strength of these gels can be enhanced through surface modification, multi-component mixing, and embedding. The main production processes involved are sol-gel and cross-linking methods. Additionally, this paper reviews various applications of alginate composite gels for common heavy metals, rare earth elements, and radionuclides and elucidates the adsorption mechanism of alginate composite gels. This study aimed to provide a reference for synthesising new, efficient, and environmentally friendly alginate-based adsorbents and to contribute new ideas and directions for addressing the issue of heavy metal pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Separation/preconcentration procedures are of great importance in the elemental analysis. In this context, layered double hydroxides (LDH) have emerged as promising sorbents in dispersive solid phase extraction (DSPE) procedures. By optimizing the DSPE procedure, lower limits of detection (LOD) can be achieved, making less sensitive detection methods viable for accurate quantification of the (ultra)trace analytes. This is of significant importance from a financial standpoint, as it enables the utilization of cost-effective and readily available detection methods. The extraction procedures using LDH typically require only a few minutes to complete, with some procedures taking as little as 1.5 min. Many studies have reported techniques that eliminate the need for centrifugation, which results in time savings and reduced sample handling. This is particularly important for ultratrace analysis. However, it has been observed that the use of certified reference materials (CRM) to validate the reliability of the developed extraction procedures is often overlooked. The literature also demonstrates inconsistencies in the terminology and abbreviations employed for extraction procedures, which may cause confusion. LDH, extensively studied for various purposes, offer a wide range of modifications and can form composites with other materials, enhancing their surface characteristics and adsorption performance. The development of novel and effective nanocomposites will undoubtedly be a research objective in this field of analytical chemistry, aiming to advance the reliability of extraction procedures. Moreover, integrating of LDH-based DSPE procedures with appropriate detection methods can enable potential automation and pave the way for online applications.

Heavy metals contaminated soils are posing severe threats to food safety worldwide. Heavy metals absorbed by plant roots from contaminated soils lead to severe plant development issues and a reduction in crop yield and growth. The global population is growing, and the demand for food is increasing. Therefore, it is critical to identify soil remediation strategies that are efficient, economical, and environment friendly. The use of biochar and slag as passivators represents a promising approach among various physicochemical and biological strategies due to their efficiency, cost-effectiveness, and low environmental impact. These passivators employ diverse mechanisms to reduce the bioavailability of metals in contaminated soils, thereby improving crop growth and productivity. Although studies have shown the effectiveness of different passivators, further research is needed globally as this field is still in its early stages. This review sheds light on the innovative utilization of biochar and slag as sustainable strategies for heavy metal remediation, emphasizing their novelty and potential for practical applications. Based on the findings, research gaps have been identified and future research directions proposed to enable the full potential of passivators to be utilized effectively and efficiently under controlled and field conditions., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by in vivo experiments that the bionanorobot can inhibit persistent enlargement of the liver caused by zinc ion poisoning.

The toxicity and persistence of heavy metals has become a serious problem for humans. These heavy metals accumulate mainly in wastewater from various industries' discharged effluents. The recent trends in research are now focused not only on the removal efficiency of toxic metal particles, but also on their effective reuse as catalysts. This review discusses the types of heavy metals obtained from wastewater and their recovery through commonly practiced physico-chemical pathways. In addition, it covers the advantages of the new system for capturing heavy metals from wastewater, as compared to older conventional technologies. The discussion also includes the various structural aspects of trapping systems and their hypothesized mechanistic approaches to immobilization and further rejuvenation of catalysts. Finally, it concludes with the challenges and future prospects of this research to help protect the ecosystem.

In recent years, nanocellulose-based materials have been increasingly applied as a lot of biosorbents for the treatment of water pollutants due to their large specific surface area, easy modification, environmental friendliness, and reproducibility. In this review, surface modification of nanocellulose-based adsorbents with various effective adsorption groups is described, as well as polymer grafting and hybrid composite fabrication. The adsorption mechanisms involved in the adsorption process of pollutants by adsorbents are further analysed and summarized. The regeneration methods of nanocellulose adsorbents with different adsorption mechanisms are also demonstrated. In addition, this paper also briefly describes the forms of nanocellulose-based adsorbents with large-scale application including membranes, gels, flocculants and magnetic composites., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Eye shadows, which are products willingly and frequently used by women and even children, have been reported in literature to contain toxic metals. In this work, a total of 94 eye shadows samples available on the Polish market were collected. Eye shadow products have been selected in order to include several parameters important from the point of view of the typical consumer such as: product type (mat/pearl), consumer group (for adults and children), price range (very cheap, medium price, expensive and very expensive), color (twelve different colors were tested), manufacturer (eight brands were investigated) or country of production (four countries were included). The concentration of selected metals (Ag, Ba, Bi, Cd, Pb, Sr, Tl) was determined by ICP-MS technique after the sample extraction with a mixture of nitric acid and hydrogen peroxide in a microwave closed system. For Ag, Cd and Tl, some results were below the established limit of quantification for the employed technique. The presence of strontium, barium, lead and bismuth was confirmed in all studied samples. The obtained results for analyzed elements were, in general, quite comparable with the data reported by other authors. A small number of samples exceeding the permissible values (two samples were beyond the limit value for Cd of 0.5 mg/kg and one exceed the acceptable concentration for Pb of 10 mg/kg) also proves a relatively good condition of the Polish cosmetics market and suggests insubstantial risk for the potential consumers. The results gathered for some of the eye shadows intended for children turned out to be alarmingly high, in particular for elements such as Cd. The highest concentration of Cd reached almost 4 mg/kg, while of Pb amounted to 16 mg/kg. The presence of the statistically significant differences was confirmed for all included parameters with an exception of the color of the eye shadow. Considering the results acquired only for Cd and Pb with respect to the country of origin, the least contaminated cosmetics by metallic impurities seem to be the one produced in Canada, while the ones presenting the highest health risk among all studied eye shadows are make-up cosmetics originating from Poland and Italy. Multivariate analysis of a large data set using CA methods and PCA provided valuable information on dependencies between variables and objects.

Designing an environmentally benign bio-adsorbent for the removal of heavy metal ions from aqueous medium was a sustainable strategy to ensure water safety. Herein, three-dimensional macroscopic aminosilyated nanocellulose aerogels (APTM S -modified TO-NFC) for the removal of heavy metal ions in water were successfully synthesized from bamboo-derived TEMPO-oxidized nanofibrillated cellulose (TO-NFC) and aminopropyltrimethoxysilane (APTMs) via a facile freeze-drying process. Owing to a relatively high BET surface area (129.32 m 2  g -1 ), high porosity (99.14%) as well as high substitution degree of amino groups (0.41), the resulting APTM S -modified TO-NFC aerogel exhibited good adsorption capacity of 99.0, 124.5, and 242.1 mg g -1 for Cu 2+ , Cd 2+ and Hg 2+ , respectively. Furthermore, the crosslinked and three-dimensionally porous architecture imparted it with relatively high compression strength, good excellent stability in water, and ease of recyclability from water after the usage. The pH value of the solution had a great influence on adsorption efficiency of the aerogel adsorbent, and optimal adsorption efficiency could be achieved at pH 3-7. Thermodynamic parameters suggested the spontaneous and endothermic nature of adsorption process. This work provides a facile method for preparing sustainable bio-adsorbent for effective heavy metal ions removal from aqueous medium., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A novel dispersive magnetic solid phase microextraction (d-MSPE) method using ionic liquid-coated amino silanized magnetic graphene oxide (MGO@SiO 2 -APTES-IL) as adsorbent has been established for enriching and extracting lead(II), copper(II) and cadmium(II) in shellfish samples. The novel nanocomposite was proved synthesized successfully by various characterization technologies. Parameters that could affect the recoveries of target ions were investigated and optimized focusing on adsorption and desorption using Box-Behnken design of response surface methodology (BBD-RSM). The limits of detection (LODs) for three target heavy metal ions were 2.42, 3.36, 3.75 ng L -1 , respectively. Additionally, the maximum adsorption capacities of the nanocomposite for target ions were 251.23, 138.51, 159.31 mg g -1 at 298 K, respectively, the nanoadsorbent can be regenerated without significant adsorption capacities loss for four times. These observations revealed that the novel nanocomposite can be used as an excellent adsorbent for separation and preconcentration of the target ions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A novel imprinted biocomposite and its non-imprinted form were developed by melaminating and crosslinking of chitosan coated onto a bio-based activated carbon and characterized using FTIR, BET, FESEM-EDS and XRD. Nickel, 4-Toluenesulfonyl chloride, and glutaraldehyde were used as a template, converter of hydroxyl and amine groups to good leaving groups, and cross-linker, respectively. The factors affecting adsorptivity and imprinting factor were optimized by using the Taguchi method for the subsequent comparative adsorptivity, kinetics, isotherms, selectivity, and reusability studies of imprinted biocomposite with its non-imprinted one. The pseudo-first-order and Langmuir models were best fitted to the experimental kinetics and equilibrium isotherm data, respectively. The maximum Ni (II)) adsorptivity of 109.86 mg/g, the imprinting factor (I·F) of 5.45 and Ni (II) selectivity coefficients values of 3.13, 4.48, 3.72, 2.51 for Ni (II) toward Zn (II), Cd (II), Cu (II) and Pb (II), respectively, were obtained at optimum conditions. After five consecutive adsorption-desorption cycles, the biocomposites still presented a high adsorptivity (>83%), indicating their excellent reusability., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Drains from coal mines remain a worrisome point-source of toxic metal/metalloid pollutions to the surface- and ground-waters worldwide, requiring sustainable remediation strategies. Understanding the microbial community subtleties through microbiome and geochemical data can provide valuable information on the problem. Furthermore, the autochthonous microorganisms offer a potential means to remediate such contamination. The drains from Onyeama coal mine in Nigeria contained characteristic sulphates (313.0 ± 15.9 mg l -1 ), carbonate (253.0 ± 22.4 mg l -1 ), and nitrate (86.6 ± 41.0 mg l -1 ), having extreme tendencies to enrich receiving environments with extremely high pollution load index (3110 ± 942) for toxic metals/metalloid. The drains exerted severe degree of toxic metals/metalloid contamination (Degree of contamination: 3,400,000 ± 240,000) and consequent astronomically high ecological risks in the order: Lead > Cadmium > Arsenic > Nickel > Cobalt > Iron > Chromium. The microbiome of the drains revealed the dominance of Proteobacteria (50.8%) and Bacteroidetes (18.9%) among the bacterial community, whereas Ascomycota (60.8%) and Ciliophora (12.6%) dominated the eukaryotic community. A consortium of 7 autochthonous bacterial taxa exhibited excellent urease activities (≥ 253 µmol urea min -1 ) with subsequent stemming of acidic pH to > 8.2 and sequestration of toxic metals (approx. 100% efficiency) as precipitates (15.6 ± 0.92 mg ml -1 ). The drain is a point source for metals/metalloid pollution, and its bioremediation is achievable with the bacteria consortium., (© 2021. The Author(s).)

The work describes the results of the first application of 2,6-bis(4-methoxybenzoyl)-diaminopyridine ( L ) for the recovery of noble metal ions (Au(III), Ag(I), Pd(II), Pt(II)) from aqueous solutions using two different separation processes: dynamic (classic solvent extraction) and static (polymer membranes). The stability constants of the complexes formed by the L with noble metal ions were determined using the spectrophotometry method. The results of the performed experiments clearly show that 2,6-bis(4-methoxybenzoyl)-diaminopyridine is an excellent extractant, as the recovery was over 99% for all studied noble metal ions. The efficiency of 2,6-bis(4-methoxybenzoyl)-diaminopyridine as a carrier in polymer membranes after 24 h of sorption was lower; the percentage of metal ions removal from the solutions (%R s ) decreased in following order: Ag(I) (94.89%) > Au(III) (63.46%) > Pt(II) (38.99%) > Pd(II) (23.82%). The results of the desorption processes carried out showed that the highest percentage of recovery was observed for gold and silver ions (over 96%) after 48 h. The results presented in this study indicate the potential practical applicability of 2,6-bis(4-methoxybenzoyl)-diaminopyridine in the solvent extraction and polymer membrane separation of noble metal ions from aqueous solutions (e.g., obtained as a result of WEEE leaching or industrial wastewater).

Removal of non-biodegradable heavy metals has been the top priority in wastewater treatment and the development of green technologies remains a significant challenge. We demonstrate that phosphorylated nanoscale zero-valent iron (nZVI) is promising for removal of heavy metals (Ni II , Cu II , Cr VI , Hg II ) via a boosted Kirkendall effect. Phosphorylation confines tensile hoop stress on the nZVI particles and "breaks" the structurally dense spherical nZVI to produce numerous radial nanocracks. Exemplified by Ni II removal, the radial nanocracks favor the facile inward diffusion of Ni II and the rapid outward transport of electrons and ferrous ions through the oxide shell for surface (Ni II /electron) and boundary (Ni II /Fe 0 ) galvanic exchange. Accompanied by a pronounced hollowing phenomenon, phosphorylated nZVI can instantly reduce and immobilize Ni II throughout the oxide shell with a high capacity (258 mg Ni g -1  Fe). For real electroplating factory wastewater treatment, this novel nZVI performs simultaneous Ni II and Cu II removal, producing effluent of stable quality that meets local discharge regulations., (© 2021 Wiley-VCH GmbH.)

Lignocellulosic fibers extracted from plants are considered an interesting raw material for environmentally friendly products with multiple applications. This work investigated the feasibility of using hemp- and flax-based materials in the form of felts as biosorbents for the removal of metals present in aqueous solutions. Biosorption of Al, Cd, Co, Cu, Mn, Ni and Zn from a single solution by the two lignocellulosic-based felts was examined using a batch mode. The parameters studied were initial metal concentration, adsorbent dosage, contact time, and pH. In controlled conditions, the results showed that: (i) the flax-based felt had higher biosorption capacities with respect to the metals studied than the hemp-based felt; (ii) the highest removal efficiency was always obtained for Cu ions, and the following order of Cu > Cd > Zn > Ni > Co > Al > Mn was found for both examined biosorbents; (iii) the process was rapid and 10 min were sufficient to attain the equilibrium; (iv) the efficiency improved with the increase of the adsorbent dosage; and (v) the biosorption capacities were independent of pH between 4 and 6. Based on the obtained results, it can be considered that plant-based felts are new, efficient materials for metal removal.

Removal of toxic metal ions using adsorbents is a well-known strategy for water treatment. While chitosan and cellulose can adsorb weakly some types of metals, incorporating thiols as metal chelating agents can improve their sorption behaviors significantly. Presented in this review are the various chemical modification strategies applicable for thiolation of chitosan and cellulose in the forms of mercaptans, xanthates and dithiocarbamates. Moreover, much attention has been paid to the specific strategies for controlling the thiolation degree and characterization approaches for establishing the structure-property relationship. Also, the kinetics and isotherm models that elucidate the adsorption processes and mechanisms induced by the thiomers have been explained. These thiomers have found great potentials in the applications associated with metal removal, metal recovery and metal detection., (© 2021 The Chemical Society of Japan & Wiley-VCH GmbH.)

A new synthesized polyaniline/starch/hematite bio composite (PANI/S/Fe 2 O 3 BC) has been studied as an effective material for on-site water remediation. PANI/S/Fe 2 O 3 BC was developed by combining the techniques of co-precipitation and interfacial polymerization in the presence of aqueous starch solution in an acidic medium under ultrasonic irradiation. The nano-morphologies and structures of the designed PANI/S/Fe 2 O 3 BC were evaluated by various techniques relative to PANI and Fe 2 O 3 nanoparticles. In single and multiple systems, PANI/S/Fe 2 O 3 BC was evaluated as a possible adsorbent for different heavy metals, including As 3+ , Zn 2+ , and Co 2+ , relative to PANI and Fe 2 O 3 nanoparticles. In terms of pH value, operating temperature, initial heavy metal concentration, contact time, adsorbent dose and competitive ions in the solutions, the adsorption process was optimized. For 92% overall adsorption of Co 2+ and 100% overall adsorption of both As 3+ and Zn 2+ , the adsorption equilibrium was achieved within 60 and 120 min, respectively. In addition, adsorption thermodynamic analysis shows that the As 3+ ions adsorption process was not random and the pseudo-second-order fitted with experimental results. Moreover, PANI/S/Fe 2 O 3 BC was evaluated as an antibacterial agent against Gram-negative bacteria (Salmonella typhimurium) and Gram-positive bacteria (S. aureus, Methicillin-Resistant Staphylococcus, Aureus Clinical isolate and Bacillus subtilis). The reported performances indicated that the PANI/S/Fe 2 O 3 BC is a potent candidate for industrial water bioremediation., (Copyright © 2021. Published by Elsevier B.V.)

A low-cost, collectable, and efficient material is essential for adsorbing water pollution, such as dyes and heavy metal ions pollution. In this work, we proposed a novel strategy for the preparation of an efficient and collectable magnetic aerogel as adsorbent for dye. The magnetic aerogels were prepared from sodium carboxymethylcellulose (CMC) hydrogel using citric acid (CA) as the crosslinker, followed by vacuum freeze-drying technique to obtain aerogels. The effects of magnetic Fe 3 O 4 nanoparticle contents on the adsorption properties of the aerogels were investigated. The results show that the as-prepared magnetic composite aerogels exhibit porous structure and display good adsorption and collectable performance for methylene blue (MB) in water with the removal rate of 97.5% in 6 h. The maximum compress strength and absorption capacity of the magnetic aerogel with 1 wt% Fe 3 O 4 nanoparticle loading for MB is 0.13 MPa and 83.6 mg/g, respectively. Aerogels with Fe 3 O 4 nanoparticles exhibited magnetism which enables the aerogels to easily collect. This excellent structure stability and collectability guarantees long-term integrity and floatability of the magnetic aerogels in water., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Lead detection for biological environments, aqueous resources, and medicinal compounds, rely mainly on either utilizing bulky lab equipment such as ICP-OES or ready-made sensors, which are based on colorimetry with some limitations including selectivity and low interference. Remote, rapid and efficient detection of heavy metals in aqueous solutions at ppm and sub-ppm levels have faced significant challenges that requires novel compounds with such ability. Here, a UiO-66(Zr) metal-organic framework (MOF) functionalized with SO3H group (SO3H-UiO-66(Zr)) is deposited on the end-face of an optical fiber to detect lead cations (Pb2+) in water at 25.2, 43.5 and 64.0 ppm levels. The SO3H-UiO-66(Zr) system provides a Fabry-Perot sensor by which the lead ions are detected rapidly (milliseconds) at 25.2 ppm aqueous solution reflecting in the wavelength shifts in interference spectrum. The proposed removal mechanism is based on the adsorption of [Pb(OH2)6]2+ in water on SO3H-UiO-66(Zr) due to a strong affinity between functionalized MOF and lead. This is the first work that advances a multi-purpose optical fiber-coated functional MOF as an on-site remote chemical sensor for rapid detection of lead cations at extremely low concentrations in an aqueous system.

Toxic metal phytoextraction potential of some higher plants, the white mustard (Sinapis alba L.), perennial rye grass (Lolium perenne L.) and also two cultivated plants, as green pea (Pisum sativum L. var. Rajnai törpe), radish (Raphanus sativus L. var. Szentesi óriás vaj), was studied in a field experiment, along the river Danube in close vicinity of an industrial town, Dunaújváros, Hungary. Soil/sediment and the various plant organs (leaves, stems and roots) were assessed for the contamination with some potentially toxic elements (PTE), such as the cadmium (Cd), nickel (Ni), copper (Cu), and zinc (Zn). It was found that Cd and Ni concentration was below, while the Cu and Zn elements were above the Hungarian permissible limits in each of the studied soil/sediment samples. Bioconcentration factor (BAF) was less than 1 in the shoot biomass of test plant samples and followed the order of Cu > Zn > Cd and Ni. Phytoremediation potential of selected test plants was found to be rather limited. The translocation factor (TF) was more than 1 for Cu and Zn elements, at each test plants. Cadmium was translocated into the leaves in case of the radish, only. Considering of the potential human daily intake of metals (DIM), it was less than 1 both for the adults and for the children. Health risk index (HRI) values of children, however, were higher than 1 for the Cd in case of radish, and for Zn and Cu in case of the pea. Results suggest that consumption of these plants grown in gardens of contaminated sediments can result in some risks for citizens in the industrial town of Dunaújváros. Further studies are required to identify appropriate plants with greater toxic metal phytoextraction potential.

Ultrasound-assisted soil washing processes were investigated for the removal of heavy metals (Cu, Pb, and Zn) in real contaminated soils using HCl and EDTA. The ultrasound-assisted soil washing (US/Mixing) process was compared with the conventional soil washing (Mixing) process based on the mechanical mixing. High removal efficiency (44.8% for HCl and 43.2% for EDTA) for the metals was obtained for the most extreme conditions (HCl 1.0 M or EDTA 0.1 M and L:S = 10:1) in the Mixing process. With the aide of ultrasound, higher removal efficiency (57.9% for HCl and 50.0% for EDTA) was obtained in the same extreme conditions and similar or higher removal efficiency (e.g., 54.7% for HCl 0.5 M and L:S = 10:1 and 50.5% for EDTA 0.05 M and L:S = 5:1) was achieved even in less extreme conditions (lower HCl or EDTA concentration and L:S ratio). Therefore, it was revealed that the US/Mixing was advantageous over the conventional Mixing processes in terms of metal removal efficiency, consumption of chemicals, amount of generated washing leachate, and volume/size of washing reactor. In addition, the heavy metals removal was enhanced for the smaller soil particles in the US/Mixing process. It was due to more violent movement of smaller particles in slurry phase and more violent sonophysical effects. In order to understand the mechanism of ultrasonic desorption, the desorption test was conducted using the paint-coated beads with three sizes (1, 2, and 4 mm) for the free and attached conditions. It was found that no significant desorption/removal of paint from the beads was observed without the movement of beads in the water including floatation, collision, and scrubbing. Thus, it was suggested that the simultaneous application of the ultrasound and mechanical mixing could enhance the physical movement of the particles significantly and the very high removal/desorption could be attained., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Heavy metal pollution has become more and more serious with industrial development and resource exploitation. Because heavy metal ions are difficult to be biodegraded, they accumulate in the human body and cause serious threat to human health. However, the conventional methods to detect heavy metal ions are more strictly to the requirements by detection equipment, sample pretreatment, experimental environment, etc. Aptasensor has the advantages of strong specificity, high sensitivity and simple preparation to detect small molecules, which provides a new direction platform in the detection of heavy metal ions. This paper reviews the selection of aptamers as target for heavy metal ions since the 21th century and aptasensors application for detection of heavy metal ions that were reported in the past five years. Firstly, the selection methods for aptamers with high specificity and high affinity are introduced. Construction methods and research progress on sensor based aptamers as recognition element are also introduced systematically. Finally, the challenges and future opportunities of aptasensors in detecting heavy metal ions are discussed.

Herein, a facile yet efficient template method to fabricate macroporous cellulose beads (MCBs) is reported. In this method, micro-size CaCO 3 is utilized to create macroporous structure for fast mass transfer, and tentacle-type poly(hydroxamic acid) as adsorption ligand is immobilized on the MCBs to improve adsorption capacity. The obtained tentacle-type poly(hydroxamic acid)-modified MCMs (TP-CMCBs) show uniform spherical shape (about 80 μm), bimodal pore system (macropores≈3.0 μm; diffusional pores≈14.5 nm), and high specific surface area (52.7 m 2 /g). The adsorption performance of TP-CMCBs is evaluated by heavy metal ions adsorption. TP-CMCBs exhibit not only high adsorption capacities (342.5, 261.5 and 243.2 mg/g for Cu 2+ , Mn 2+ and Ni 2+ , respectively.), but also fast adsorption rate (>70% of its equilibrium uptake within 30 min). Additionally, TP-CMCBs have excellent reusability, as evidenced by that the adsorption capacities have no obvious change even after five-time consecutive adsorption-desorption cycles. All results demonstrate that the proposed TP-CMCBs have great potential in removal of heavy metal ions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Elemental sulfur is generated in large quantities when crude oil is refined. This elemental sulfur has limited use other than the production of sulfuric acid. Recently, the development of 'inverse vulcanised' polymers has attracted the attention of researchers. These polymers are formed from elemental sulfur and a small molecule alkene. The affinity of sulfur for heavy metals gives these polymers potential for specific adsorption; however, there is a lack of incorporation of high specific surface areas in pure polymers. Herein, we report the first mesoporous polymer generated using inverse vulcanised polymers, with a BET surface area of 236.04 m2 g-1. We explore the properties of polymers as an absorption medium for potent neurotoxin Hg(ii).

Background: Porphyra haitanensis now faces serious heavy metal pollution problems. Natural deep eutectic solvents (NADESs) have been recognized as a novel class of sustainable solvents, which can be used for heavy metal removal. In this study, 28 kinds of NADESs were prepared and investigated as eluent in the removal of lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and copper (Cu) from P. haitanensis for the first time, and the adsorption mechanism of NADESs was also studied., Results: The removals were greatly improved by NADESs compared with control where the removal rates of Pb, Cd, Cr, As and Cu were 17.4-87.54%, 57.54-100%, 9.8-48.59%, 21.32-78.24% and 11.68-79.73%, respectively. The optimal condition was 10% water content and solid-liquid ratio of 1:20. Moreover, the addition of 20% natural surfactant arabic gum can further increase the heavy metals removal rates of NADESs. The adsorption mechanism experiments showed that the pseudo second-order model and the Freundlich adsorption model can better explain the adsorption mechanism of NADESs on heavy metals removal., Conclusion: Taken together, a green and efficient method for removing heavy metals from P. haitanensis was established. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

The presence of inorganic pollutants such as Cadmium(II) and Chromium(VI) could destroy our environment and ecosystem. To overcome this problem, much attention was directed to microbial technology, whereas some microorganisms could resist the toxic effects and decrease pollutants concentration while the microbial viability is sustained. Therefore, we built up a complementary strategy to study the biofilm formation of isolated strains under the stress of heavy metals. As target resistive organisms, Rhizobium -MAP7 and Rhodotorula ALT72 were identified. However, Pontoea agglumerans strains were exploited as the susceptible organism to the heavy metal exposure. Among the methods of sensing and analysis, bioelectrochemical measurements showed the most effective tools to study the susceptibility and resistivity to the heavy metals. The tested Rhizobium strain showed higher ability of removal of heavy metals and more resistive to metals ions since its cell viability was not strongly inhibited by the toxic metal ions over various concentrations. On the other hand, electrochemically active biofilm exhibited higher bioelectrochemical signals in presence of heavy metals ions. So by using the two strains, especially Rhizobium -MAP7, the detection and removal of heavy metals Cr(VI) and Cd(II) is highly supported and recommended.

Gum karaya is a polysaccharide that has several industrial applications in the pharmaceutical, food, and environmental fields owing to its hydrophilic, anionic, and biocompatible nature. Gum karaya and its modified forms have been assessed for drug delivery, wastewater treatment, and food industry applications. This review provides a comprehensive overview of various synthetic methods of modification of gum karaya, such as grafting initiated through free radical, microwave-assisted grafting, radiation-assisted, and enzyme-assisted modification methods. In addition, the review outlines collective industrial applications of modified gum karaya in drug delivery systems, removal of heavy atoms, dyes, food, and other biological activities, and suggests possible prospects for gum karaya modification and their remarkable industrial applications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)