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The modified coconut shell biochars (MCSBCs) were fabricated and their adsorptions for Pb(II) were evaluated, in which waste coconut shell was used as the raw material, both ZnCl2 and KMnO4 were applied as the inorganic modifiers. FT-IR spectra, TGA, SEM and BET techniques were utilized to characterize their properties. It was spotted that the thermal stability of UCSBC could arrive at 500 °C. The BET specific surface areas of both Zn- and Mn-modified MCSBCs (485.137, 476.734 m2/g) were highly decreased as compared with that of UCSBC (3528.78 m2/g). In contrast, the average pore diameters of both Zn- and Mn-modified MCSBCs (3.295, 3.803 nm) were smaller than that of UCSBC (3.814 nm). These findings reveal that the modification of CSBC didn't change its pore size. Their adsorptions for Pb(II) were performed and some controlling factors involving pH, contact time, starting concentration and temperature were explored. Moreover, the experiment data were fitted via linear and non-linear techniques. It was found that the Langmuir maximal adsorption amounts of un-modified coconut shell biochar (UCSBC), Zn-modified and Mn-modified MCSBCs for Pb(II) could reach 31.653, 86.547 and 93.666 mg/g, respectively. Two-parameter kinetic models exposed that Pb(II) adsorption on UCSBC, Zn-modified and Mn-modified MCSBCs obeyed both the Lagergren first-order (non-linear R2 = 0.990, 0.954, 0.953, respectively) and Avrami fractional-order (non-linear R2 = 0.989, 0.946, 0.945, respectively) kinetic models. Two-parameter and three-parameter isotherm models verified that Pb(II) adsorption on UCSBC, Zn-modified and Mn-modified MCSBCs followed the Langmuir (non-linear R2 = 0.992, 0.997, 0.993, respectively) as well as Sips (non-linear R2 = 0.992, 0.997, 0.992, respectively) isotherm models. The computation of thermodynamic parameters evidenced that the modification of UCSBC via KMnO4 and ZnCl2 can effectively rise its adsorption for Pb(II), exhibiting promising applications in the handling of metal-bearing water.

KMnO4-modified biochar (KM/biochar) derived from cotton stem is prepared with different cotton stem/KMnO4 ratios for Pb(II) removal from wastewater. The characterization analysis indicates that KM/biochar has abundant surface functional groups and large surface area, contributing to Pb(II) removal. Pb(II) adsorption on KM/biochar can be accurately analyzed using the Pseudo-second order and Hill model. The maximum Pb(II) adsorption capacity of KM/biochar is 144.49 mg/g at pH of 5. Pb(II) adsorption on KM/biochar is spontaneous based on thermodynamics analysis with the enthalpy value of the 8.54 kJ/mol. Coexisted ions such as Na+, K+, Ca2+ and Mg2+ have slightly influenced on Pb(II) adsorption process. The regeneration experiment analysis indicates that KM/biochar shows excellent Pb(II) adsorption capacity after three cycles. The existence of CO2 can contribute to Pb(II) removal from wastewater. Pb(II) adsorption mechanism includes precipitation, cation exchange, electrostatic attraction and π-π interaction. These above analysis results indicate that the waste cotton stem can be converted into the high-efficient KM/biochar for Pb(II) removal from wastewater.

The aim of removing Pb(II) from water is to minimize the potential harm posed by toxic metals to both human health and the environment. To achieve this, a covalent organic framework adsorbent called TFPOTDB-SO3H was developed using a condensation process involving 2,5-diaminobenzenesulfonic acid and 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine. This adsorbent exhibited excellent properties such as high repeatability, selectivity, and easy solid–liquid separation. Under conditions of pH = 6.0 and 298 K, the TFPOTDB-SO3H demonstrated impressive capability of adsorbing Pb(II). In a brief span of 10 min, it attained a special elimination rate of 99.40 % and shown its capacity to adsorb up to 500.00 mg/g. The adsorbent presented effective removal of Pb(II) from a solution that had a mixture of various ions, showcasing its proficiency in capturing the contaminant, with a partition coefficient (Kd) of 3.99 × 106 mL/g and an adsorption efficiency of 99.75 % among six coexisting ions. The pseudo-second-order kinetic model was observed to govern the adsorption process kinetics, while the Langmuir isotherm model confirmed monolayer chemisorption as the mechanism for Pb(II) removal. Thermodynamic analysis indicated that the uptake process was both exothermic and spontaneous. Furthermore, the adsorbent maintained a significant adsorption efficiency of 89.63 % for Pb(II) even after undergoing four consecutive adsorption–desorption cycles. These findings collectively suggest that TFPOTDB-SO3H has excellent potential for effectively adsorbing and removing Pb(II) heavy metal ions from wastewater.

The occurrence of excessive levels of bivalent plumbum (Pb(II)) in wastewater poses a notable threat to both human health and ecological safety. In this study, orthogonal experiments were conducted to prepare coprecipitation-modified biochar (C-BC) and impregnation pyrolysis-modified biochar (I-BC) via potassium permanganate (KMnO 4 ) for removing Pb(II) from wastewater. Three types of modified biochars (BCs) (Mn-BCs) namely, C-BC 400 , I-BC 400 , and I-BC 700 , were selected as high-efficiency adsorbents on the basis of their high removal rates (87.2%, 88.0%, and 91.2%, respectively) for 400 mg/L Pb(II) solutions. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM)‒energy-dispersive X-ray spectroscopy (EDS) analysis results indicated that Mn elements were distributed only on the outer surfaces of the C-BC 400 particles but occurred on the outer surface and were stably embedded in the I-BC 400 and I-BC 700 particles. Compared with those of the pristine (BCs), the Pb(II) adsorption rates of C-BC 400 , I-BC 400 , and I-BC 700 increased by factors of 3.75, 2.09, and 5.70, respectively. The Pb(II) adsorption capacities of C-BC 400 , I-BC 400, and I-BC 700 (182.28, 133.16, and 69.25 mg/g, respectively) were significantly greater than those of the pristine BCs produced at 400 °C (45.43 mg/g) and 700 °C (40.71 mg/g). The excellent adsorption ability of Mn-BCs for Pb(II) depends on various adsorption mechanisms, including complexation, electrostatic attraction, surface adsorption, and ion exchange. These results suggest that Mn-BCs exhibit high application potential in the remediation of Pb(II)-contaminated 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 Inc. All rights reserved.)

In this work, MIL-100(Fe)-decorated mesoporous carbon powders (MC@MIL-100(Fe)) were prepared by in situ growth of MIL-100(Fe) on the surface of ZIF-8 framework-based mesoporous carbons (MC). The hybrid material was characterized using SEM equipped with EDS mapping for morphology investigation, X-ray photoelectron spectroscopy for chemical valence analysis, and X-ray diffraction for crystal structure determination. The developed sensor separated from the traditional bismuth film decoration, and simultaneously, MC@MIL-100(Fe) was applied for the first time to electrochemically detect trace amounts of Pb(II) and Cd(II). The fabricated MC@MIL-100(Fe)-based electrochemical sensor showed excellent response to the target analytes at –0.55 and − 0.75 V for lead and cadmium ions, respectively. By adjusting some measurement parameters, that is, the loading concentration of MC@MIL-100(Fe), acidity of the HAc-NaAc buffer (ABS), deposition potential, and deposition time, the analytical performance of the proposed electrochemical sensor was examined by exploring the calibration curve, repeatability, reproducibility, stability, and anti-interference under optimized conditions. The response current of the proposed MC@MIL-100(Fe) electrochemical sensor showed a well-defined linear relationship in the concentration ranges of 2–250 and 2–270 μg·L−1 for Cd(II) and Pb(II), respectively. In addition, the detection limits of the sensor for Cd(II) and Pb(II) were 0.18 and 0.15 μg L−1, respectively, which are well below the World Health Organization (WHO) drinking water guideline value. The MC@MIL-100(Fe) can be potentially used as an electrochemical platform for monitoring heavy metals in surface water, with satisfactory results.

This research work reports on novel materials obtained when coral limestones (PCLS) was calcined at 800 and 900 °C to produce CLS-800 and CLS-900. The materials were characterized by SEM, BET, XRD, FTIR and UV-Vis. The calcined materials exhibited BET surface areas of 64.10 and 63.28 m2/g for CLS-800 and CLS-900 respectively which are significantly higher than that of the starting material (PCLS) 20.45 m2/g. XRD analysis revealed that PCLS was dominated by CaCO3 aragonite while CLS-800 and CLS-900 was a mixture of calcite and CaO. FTIR results revealed that all adsorbents exhibited peaks for (-CO32−) and (CaO). UV-Vis results revealed that CLS-800 and CLS-900 were both blue and red when compared to the starting material. PCLS, CLS-800 and CLS-900 were used as adsorbents for Cr(VI) and Pb(II) ion solutions. The maximum adsorption capacities for Cr(VI) and Pb(II) were 99.12 and 98.42 mg/g onto CLS-800 at pH 2 and 8 respectively. The adsorption kinetic data suited PFO kinetic model better than PSO. While isotherm data best fitted Freundlich model. The removal of Cr(VI) onto all adsorbents was favoured at low temperature whilst Pb(II) favoured high temperature. Hence, negative (ΔHo) values for Cr(IV) ions indicated exothermic process while positive (ΔHo) values for Pb(II) ions indicated an endothermic process. The adsorption mechanism was through synergistic processes; hydrogen bonding, complexation, electrostatic, surface deposition and intraparticle diffusion. The reusability of the adsorbents was tested for four cycles.

Lead (Pb(II)) is a pervasive heavy metal toxin with many well-established negative effects on human health. Lead toxicity arises from cumulative, repeated environmental exposures. Thus, prophylactic strategies to protect against the bioaccumulation of lead could reduce lead-associated human pathologies. Here we show that DNA and RNA aptamers protect C. elegans from toxic phenotypes caused by lead. Reproductive toxicity, as measured by brood size assays, is prevented by co-feeding of animals with DNA or RNA aptamers. Similarly, lead-induced neurotoxicity, measured by behavioral assays, are also normalized by aptamer feeding. Further, cultured human HEK293 and primary murine osteoblasts are protected from lead toxicity by transfection with DNA aptamers. The osteogenic development, which is decreased by lead exposure, is maintained by prior transfection of lead-binding DNA aptamers. Aptamers may be an effective strategy for the protection of human health in the face of increasing environmental toxicants., Competing Interests: Declaration of Competing Interest N.G.F., A.A., and S. Ramis de Ayreflor Reyes have filed a patent application for the technology described herein. J.H.S. is a scientific co-founder of AAVAA Therapeutics and holds equity in this company. All other authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In this study, a fresh three-dimensional microsphere adsorbent (CATP@SA 3 ) was successfully synthesized by Attapulgite (ATP) and combining Chitosan (CS), incorporating them into a Sodium alginate (SA) solution, and crosslinking them in a CaCl 2 solution. Multiple analyses, including XRD, TGA, FTIR, XPS, SEM-EDS, and BET were utilized to comprehensively characterize the structural makeup of CATP@SA 3 . These analyses revealed the presence of beneficial functional groups like hydroxyl, amino, and carboxyl groups that enhance the adsorption efficiency in adsorption procedures. CATP@SA 3 was evaluated by studying different factors, including material ratio, contact time, dosage, solution pH, Pb(II) concentration, temperature, ionic strength, and aqueous environment. Three adsorption models, including kinetic, isotherm, and thermodynamic, were fitted to the experimental data. The findings demonstrated that the maximum Pb(II) adsorption capacity of CATP@SA 3 was 1081.36 mg/g, with a removal rate that exceeded 70 % even after 5 cycles of use. Furthermore, correlation adsorption models revealed that the adsorption process of Pb(II) with CATP@SA 3 was driven by a chemical predominantly reaction., 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.)

Different aminonaphetalenesulphonic acid derivatives like 5-aminonaphthalene-1-sulphonic acid (5AN1SA), 2-aminonaphthalene-1-sulphonic acid (2AN1SA), 8-aminonaphthalene-2-sulphonic acid (8AN2SA) and 4-amino-3-hydroxynaphthalene-1-sulphonic acid (4A3HN1SA) were used to construct polymer/bismuth film modified electrode for simultaneous determination of Pb(II) and Cd(II) ions with the aim of developing a cheaper and sensitive electrode that could possibly replace Nafion. Among the different modified electrodes, poly (8AN2SA)/bismuth film modified electrodes showed the highest electrochemical response for both ions. These electrochemical results were also supported by density functional theory (DFT) calculations. Based on these experimental and theoretical results, poly (8AN2SA)/bismuth film glassy carbon modified electrode was further investigated to develop a simple and sensitive electrochemical method for the simultaneous determination of Pb(II) and Cd(II) ions. After optimizing the different experimental parameters, the proposed method gave a linear range of 1–40 μg/L with the detection limit of 0.38 and 0.08 μg/L for the simultaneous determination of Pb(II) and Cd(II) ions, respectively.

Lead (Pb) and cadmium (Cd) are considered as a typical heavy metals in aqueous solution, which may pose adverse health effects on human beings. For the removal of these two pollutants, magnesium oxide (MgO) was successfully immobilized onto eucalyptus biochar (BC) matrix via simple and cost-effective pyrolysis process of MgCl2-pretreated eucalyptus biomass under high temperature (500 °C). Synthesized MgO nanoparticles-biochar composites (MBC) exhibited superior removal performance for target pollutants, and achieve 99.9% removal efficiency for Pb(II) and Cd(II) at optimum conditions (0.02 g, pH in range of 4–7, and reaction time 120, 240 min). Furthermore, the maximum theoretical adsorbing amount of MBC was 829.11 mg/g for Pb(II) and 515.17 mg/g for Cd(II). Pseudo-second-order model and Langmuir models were well-determined for isotherm and adsorption kinetics. FTIR, XRD, and XPS analysis revealed that precipitation and ion exchange was of great importance for the removal of contaminants. Besides, cation-π interaction and complexation from the carbon-containing functional groups should not be neglected. Considering the advantage of low-cost, facile preparation, and brilliant adsorption capacity, it is anticipated that MBC has a promising prospect for the broad application in Pb(II)/Cd(II)-containing wastewater treatment.

This study reveals novel data on adsorptive removal of Pb(II) from single metal solution, as well as from multi-metal solution containing Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II) ions along with Pb(II) using inorganic SiO2–MoO3 sorbent in a batch system. The results of multi-metal solution system were strongly pH-depended and due to occurred precipitation of Fe(III) in the form of hydroxide. The parameters affecting the sorption efficiency (contact time, sorbent dosage and initial analyte concentration) were evaluated for single solution system. The optimal conditions for SiO2–MoO3 sorbent indicated high affinity toward Pb(II) ions within following process parameters; pH value 3, sorbent dosage 50 ​mg and contact time 60 ​min for maximum Pb2+ concentration of 100 ​mg/L. The adsorption data for Pb(II) utilizing SiO2–MoO3 best fit to pseudo-second-order kinetic model (R2 ​= ​0.9998) and Langmuir isotherm model (R2 ​= ​0.9320) with an adsorption capacity of 222.20 ​mg/g and Reff >95%. According to thermodynamic study, the adsorption process is feasible, spontaneous and exothermic (ΔG ​= ​−18.6 ​kJ/mol, ΔH ​= ​−7.5 ​kJ/mol and ΔS ​= ​37.32 ​J/mol K). The results of present study demonstrated that SiO2–MoO3 material as a renewable sorbent for Pb(II) removal.

In this study, 2-mercaptopropionic acid was incorporated into hydrous zirconium oxide matrix to prepare 2-mercaptopropionic acid/ hydrous zirconium oxide (MPA/HZO) composite and applied to eliminate Pb(II) from aqueous environment. MPA/HZO was characterized by FTIR, TGA-DTA and SEM with EDX. Response surface methodology (RSM) was utilized for optimizing the independent variables affecting the uptake of Pb(II)). The maximum efficiency was reached at an equilibrating time of 40 min. At the optimum conditions (pH:6.8; contact time: 40 min; adsorbent dose: 0.016 g; initial concentration: 60 mg/L), 99.37% Pb(II) was successfully eliminated. Nonlinear regression analysis was applied for the investigation of isotherm and kinetic equations. Langmuir isotherm model with R2 > 0.99 was best fit model to demonstrate the adsorption of Pb(II) onto MPA/HZO. The maximum Langmuir adsorption capacity (qm) was 128.50 mg/g. Pseudo-second order kinetic model with R2 > 0.999 illustrated its best fitting to the kinetic data.

Mining activities can potentially release high levels of Pb(II) in acid mine drainage (AMD), which thereafter poses a significant threat to ecological security. In this study, green reduced graphene oxide/silver nanoparticles (rGO/Ag NPs) were successfully synthesized via a one-step approach using a green tea extract and subsequently used as a cost-effective absorbent to remove Pb(II) from AMD. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that organic functional groups in the green tea extracts, such as C=O-C, CO, and CC, acted both as reductants and stabilizers in the synthesis of rGO/Ag NPs. In addition, the removal efficiency of Pb(II) by rGO/Ag NPs (84.2 %) was much better than either rGO (75.4 %) or Ag NPs (12.3 %) alone. Also, in real AMD, the distribution coefficient (K d ) of Pb(II) (4528 mL/g), was much higher than other heavy metal indicating the adsorbent had a high selective affinity for Pb(II). Interestingly, after five cycles of use, the removal efficiency of Pb(II) by rGO/Ag NPs from AMD actually increased from 46.4 to 65.2 % due to iron oxides (i.e., Fe 2 O 3 and Fe 3 O 4 ) being generated when rGO/Ag NPs was exposed to AMD. The removal of Pb(II) via adsorption on the rGO/Ag NPs surface involved formation of hexagonal rod-like precipitates. This work demonstrated the potential of rGO/Ag NPs to be continuously used for the removal of Pb(II) from AMD., 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 adsorption of Pb(II) onto silica gel functionalized with thiosalicylic acid (TSA@)amine modified SiO2) was studied at 300, 305, 310 and 315 K. The effects of independent variables (pH, adsorbent dose and initial concentration of Pb(II)) on the removal of Pb(II) from water were evaluated and response surface methodology was applied to optimize them. Under the optimized conditions (pH: 6; adsorbent dose, 0.20 g/20 mL and initial concentration: 50 mg/L), removal efficiency of Pb(II) was 98.78%. The adsorption equilibrium data obtained from batch experiments were examined by various isotherm models. Freundlich isotherm model fitted well to the experimental data and indicating the multilayer coverage of Pb(II) on the heterogeneous surface of TSA@)amine modified SiO2. Adsorption kinetic data were investigated by surface and diffusion based kinetic models. Kinetic data fitted well to pseudo-second order model with R2 > 0.999. Elovich model with R2 > 0.999 revealed the occurrence of chemical reaction between Pb(II) and active sites of TSA@)amine modified SiO2. Thermodynamic parameters suggested the spontaneous and endothermic nature of Pb(II) adsorption onto TSA@)amine modified SiO2.

Adsorption isotherms are indispensable tools for the description of sorption processes of pollutants on adsorbents. The closeness of the equilibrium concentration (qe) to the calculated solid phase concentration (qecal) of the adsorbate, together with the co-efficient of determination (R2) and associated errors are important in determining the best goodness-of-fit model. In this work we have investigated the adsorption of Pb(II) and Cr(VI) on a nanocomposite that was prepared using magnetite nanoparticles capped with locally prepared biochar and functionalized using 3-(aminopropyl) triethoxysilane (APTES) at 3 different temperatures. Detailed discussion of data can be found in DOI:10.1016/j.micromeso.2020.110573. The sorption processes were equally analyzed utilizing both the linear and non-linear forms of Langmuir, Freundlich and Temkin equations.

A novel fabrication method for modifying alkaline lignin (AL) was reported, in which trimercapto-s-triazine trisodium salt was used as a modifier to tune surface properties of AL. Molecular structure of modified AL (FAL) was determined by 3D-EEM, synchronous fluorescence, FTIR, 13C MAS NMR and XPS. Two-dimensional correlation spectroscopy and electron localization function demonstrated that both of electrostatic and coordinate bonds formed between these functional groups and Pb(II) at higher pH of 3.0 to 6.0 while only coordinate bond at lower pH of 0.2 to 1.2. The higher the solution pH was, the stronger the adsorption capacity of FAL had. The maximum adsorption capacity (qm) of Pb(II) was 20.0, 28.2, 65.1 and 73.7 mg/g at pH of 0.2, 1.2, 3.0 and 6.0 (T = 25 °C), respectively. The adsorption performance of FAL towards Pb(II) was better by comparing with other biomass-based materials via adsorption amount, equilibrium time as well as simplicity of the synthesized steps. These results improve the understanding of FAL-Pb(II) interaction at the molecular level and facilitate a comprehensive evaluation on the treatment efficiency of FAL.

Screening a new biosorbent with low cost and high efficiency from a native plant material is a key to the adsorption of heavy metal ions from wastewater. In this study, the potential of Phytolacca americana L. as a biosorbent for Pb(II) removal from aqueous solutions was investigated. Experiments were performed to evaluate the effect of biosorbent dosage, pH, initial Pb(II) concentration and contact time on the Pb(II) removal. The results indicated that the hydroxyl, carboxyl and amine groups may take part in Pb(II) binding. HNO3-modified P. americana (HPAL) showed a significant higher uptake capacity compared to original P. americana (PAL) (p

The excessive content of lead (Pb(II)) and Staphylococcus aureus (S.aureus) seriously harms the quality of aquatic products. In this paper, a highly sensitive electrochemiluminescence (ECL) biosensor was constructed using the synergistic effect of Au NPs@Nickel-Cobalt-Metal-organic frameworks (Au@Ni-Co-MOFs) and double potential resolution function of urchin-like Au@luminol and Cadmium sulfide quantum dots (CdS QDs) for synchronous detection of Pb(II) and S.aureus in aquatic products. Au@Ni-Co-MOFs as the base material, its cube structure can improve the surface active area and sensitivity of the sensor, providing more catalytic active sites for the two functional probes. Urchin-like Au@luminol binding aptamer DNA2 specifically recognizes Pb(II), CdS QDs binding aptamer DNA3 specifically recognizes S.aureus, which collaboratively catalyzed hydrogen peroxide reduction to produce two electrochemiluminescence signals. The shared hairpin structure DNA1 binds stably to Au@Ni-Co-MOFs via the Au-S bond, and the two functional probes are complementary paired with the DNA1 respectively to ensure the specificity of the aptamer. According to the ECL intensity changes of different potentials signal sources, the synchronous detection of Pb(II) and S.aureus with different concentrations is realized. The sensor realizes the detection of two targets in aquatic products and provides a new strategy for the simultaneous detection of multiple targets., 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.)

Goethite is ubiquitous in the environment and plays key role in preserving dissolved organic matter (DOM) and deactivating potentially toxic elements (PTEs) by adsorbing DOM and PTEs. Various non-Fe metals are usually incorporated into natural goethite, substituting Fe in the goethite structure, which dramatically influence the physico-chemical properties and adsorption behavior of the goethite. In the present study, adsorption of DOM and Pb(II) on Mn-substituted goethite samples was investigated. The results displayed that the specific surface area (SSA) of mineral samples increased by 67.6% as the incorporation of Mn for Fe, from 25.71 m 2  g -1 for pure goethite to 43.09 m 2  g -1 for Mn-goethite. Besides, the Mn substitution caused more hydroxyl groups and relatively fewer positive charges on mineral surface, and Mn in the Mn-goethite samples was predominantly present as Mn(III). The amount of DOM adsorbed to per unit mass of goethite was increased as Mn content increased, which was attributed to Mn incorporation increasing the SSA of mineral samples. However, the SSA-normalized absorption capacity for goethite to DOM was decreased by Mn because Mn substitution decreased the number of positive charges of mineral samples, which weakened the electrostatic attraction between DOM and the minerals. The amount of Pb(II) adsorbed to per unit mass of goethite was increased by Mn substitution, and the amount of Pb(II) adsorbed to per unit SSA of goethite increased as the amount of Mn substitution increased, indicating that the increased capacity for adsorbing Pb was not only caused by the SSA increasing but also by there were more surface hydroxyl groups on the Mn-goethite than pure goethite and Pb(II) preferentially adsorbed to Mn sites on the Mn-goethite. The present study results showed that Mn-goethite could be used to sequester DOM and remediate soil contaminated with PTEs because Mn-goethite has a high adsorption capacity and is environmentally benign., 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 © 2023 Elsevier Inc. All rights reserved.)

The detection of Pb 2+ ions in aquatic environments and biofluid samples is crucial for assessment of human health. Herein, we synthesized two fluorescent probes (1 and 2) consisting of the peptide receptor for Pb 2+ and a benzothiazolyl-cyanovinylene fluorophore that exhibited excimer-like emission when it aggregated. The peptide-based probes sensitively detected Pb 2+ in purely aqueous solution (1% DMF) through ratiometric fluorescent response with a decrease in monomer emission at 520 nm and an increase in excimer emission at 570 nm. Specially, probe 2 showed remarkable detection features such as high selectivity for Pb 2+ over 15 metal ions, high binding affinity (K d  = 5.83 × 10 -7 M) for Pb 2+ , significant emission intensity changes, low detection limit (3.8 nM) of Pb 2+ , high water solubility, and visible light excitation (450 nm). Probe 2 was successfully used to quantify nanomolar concentration (0 ∼ 800 nM) of Pb 2+ in real water samples (ground water and tap water). Specially, 2 was successfully applied for the quantification of Pb 2+ in human serum by combination of microwave-assisted human serum digestion and filtration of digested serum by anion exchange cartridge. We clearly investigated the binding mode of 2 with Pb 2+ using 1 H NMR, IR spectroscopy, pH titration, confocal microscopy, and size analysis. The peptide-based fluorescent probe might have great application potential for sensing Pb 2+ in aquatic environments and biofluid samples., 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 © 2023 Elsevier B.V. All rights reserved.)

Lead (Pb) discharged from rural industries poses a significant threat to the environment and human health. Algal-bacterial aerobic granular sludge (A-B AGS) is a promising alternative for sewage treatment with high efficiency and good settleability. In this study, Pb(II) biosorption using fresh A-B AGS was investigated for the first time. The important role of extracellular polymeric substances (EPS) was revealed with the involved mechanisms being clarified. The desorbents for Pb recovery from Pb-loaded A-B AGS were also screened. Results showed that A-B AGS has an excellent maximum Pb adsorption capacity of 72.4 mg·g -1 at pH 6.0. EPS plays an important role in keeping microbial activity, Pb bonding, and providing metal ions (Ca, Na and Mg) for Pb ion exchanges. Electrostatic interaction, ion exchange, and bonding to functional groups may occur orderly in the Pb biosorption process and the formation of pyromorphite (Pb 5 (PO 4 ) 3 Cl) contributes to Pb biosorption. About 66 % of the adsorbed Pb was accumulated in the A-B AGS microbial cells. Na 2 EDTA (0.05 M) can recover 60.3 % of the loaded Pb with the highest microbial activity of granules being remained. All the findings will provide the theoretical basis for the large-scale application of A-B AGS to bioremediate Pb(II)-containing 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 © 2022. Published by Elsevier B.V.)

In this study, the chitosan-grafted tetracarboxylic functionalized magnetic nanoparticle (Fe 3 O 4 @TCA@CS) was synthesized via in situ co-precipitation process and amidation reaction to improve efficiency of adsorption process and obtain cost-effective adsorbents for removal of toxic Pb(II) metal from aqueous environment. The Fe 3 O 4 @TCA@CS nanocomposite was analyzed by FTIR, TEM-EDX, TGA, XRD, BET, and Zeta potential. The performance of Fe 3 O 4 @TCA@CS for Pb(II) ions adsorption was achieved as a function of pH, dose, contact time, initial Pb(II) concentration, and temperature. The influence of coexisting ions such as Na + , Ca 2+ , Mg 2+ , and Cd 2+ on removal efficiency of Pb(II) was also investigated. The results revealed that the coexisting ions had little influence on Pb(II) removal efficiency. The pseudo-first-order and Freundlich models were better to describe the adsorption of Pb(II) onto Fe 3 O 4 @TCA@CS and the maximum adsorption capacity of Pb(II) was 204.92 mg/g at pH:5.5; adsorbent dose: 0.015 g; and temperature: 298 K. Thermodynamic studies revealed that the Pb(II) adsorption onto Fe 3 O 4 @TCA@CS was an exothermic process. In conclusion, the study provides a new, simple, low-cost, and effective chitosan-based magnetic nanocomposite as a promising adsorbent with excellent adsorption capacity, magnetic separation, and reusability for Pb(II) removal from an aqueous environment., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2022. Published by Elsevier B.V.)

An O-hydroxyphenyl thiourea-modified chitosan (OTCS) with excellent Pb(II) adsorption performance and selectivity was prepared as an adsorbent. The structure and morphology of the adsorbent were systematically investigated by SEM, BET, FTIR, EDX, zeta-potential measurements, XPS and XRD. The impacts of the initial Pb(II) concentration, reaction time, temperature, pH value, and coexisting ions were explored. At pH 7 and 303 K, the maximal adsorption capacity of OTCS for Pb(II) was 208.33 mg/g, which was greater than those of other adsorbing materials reported in the literature. The metal ion adsorption kinetics and isotherm models were found to obey pseudo-second-order kinetics and the Langmuir isothermal model, indicating that the adsorption process was monolayer chemisorption. The adsorption process could proceed spontaneously, and the thermodynamic results revealed that the adsorption mechanism was an endothermic reaction. The ion exchange and chelation between the sulfur, nitrogen and oxygen groups on the adsorbent and lead ions endowed the material with excellent adsorption properties. Significantly, OTCS showed excellent selectivity toward Pb(II). Therefore, the adsorbent OTCS is expected to promote the wider application of chitosan in the adsorption of Pb(II)., 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 © 2022 Elsevier B.V. All rights reserved.)

Biogenic gold nanoparticles (AuNPs) have been extensively studied for the catalytic conversion of nitrophenols (NP) into aminophenols and the colorimetric quantification of heavy metal ions in aqueous solutions. However, the high self-agglomeration ability of colloidal nanoparticles is one of the major obstacles hindering their application. In the present study, we offered novel biogenic AuNPs synthesized by a green approach using Cistanche deserticola (CD) extract as a bioreducing agent and stabilized on poly(styrene-co-maleic anhydride) (PSMA). The prepared Au@PSMA nanoparticles were characterized by various techniques (HR-TEM, SEAD, FE-SEM, DLS, TGA, XRD, and FTIR) and studied for two applications: the catalytic reduction of 3-NP by NaBH 4 and the sensing detection of Pb 2+ ions. The optimal conditions for the synthesis of AuNPs were investigated and established at 60 °C, 20 min, pH of 9, and 0.5 mM Au 3+ . Morphological studies showed that AuNPs synthesized by CD extract were mostly spherical with a mean diameter of 25 nm, while the size of polymer-integrated AuNPs was more than two-fold larger. Since PSMA acted as a matrix keeping the nanoparticles from coagulation and maintaining the optimal surface area, AuNPs integrated with PSMA showed higher catalytic efficiency with a faster reaction rate and lower activation energy than conventional nanoparticles. Au@PSMA could completely reduce 3-NP within 10 min with a rate constant of 0.127 min -1 and activation energy of 9.96 kJ/mol. The presence of PSMA also improved the stability and recyclability of AuNPs. Used as a sensor, Au@PSMA exhibited excellent sensitivity and selectivity for Pb 2+ ions with a limit of detection of 0.03 μM in the linear range of 0-100 μM. The study results suggested that Au@PSMA could be used as a promising catalyst for the reduction of NP and the colorimetric sensor for detection of Pb 2+ ions in aqueous environmental samples., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Coexistence of heavy metals and endocrine disrupting compounds in polluted water with competitive adsorption behavior necessitates design of tailored adsorbents. In this work, β-cyclodextrin modified magnetic rice husk-derived cellulose (β-CD@MRHC) which can provide independent functional sites for effectively binding the above two types of contaminants was synthesized and used for Pb(II) and BPA elimination in both unit and multivariate systems. Characterizations results confirmed successful β-CD grafting and Fe 3 O 4 loading, and the β-CD@MRHC had excellent magnetic property for its effectively recovery from water, which was not affected by the adsorption of pollutants. The β-CD@MRHC possessed superior adsorption performance with maximal Pb(II)/BPA uptake of 266.2 or 412.8 mg/g, severally, and the adsorption equilibrium was fleetly reached in 30 and 7.5 min. Moreover, the β-CD@MRHC could accomplish synergetic Pb(II) and BPA elimination through averting their competitive behaviors owing to diverse capture mechanisms for Pb(II) (ion exchange, complexation and electrostatic attraction) and BPA (hydrogen bonding and host-guest inclusion). Furthermore, after three cycles of step-wise desorption, the binding of Pb(II) as well as BPA byβ-CD@MRHC dropped slightly in dualistic condition. In summary, β-CD@MRHC was a promising tailored adsorbent to practical application for simultaneously removing heavy metals and organic matters from wastewater with high-performance magnetic recovery., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Ratiometric fluorescent detection using dual emission bands is highly necessary to quantify Pb(II) in aquatic environment and live cells. We synthesized a ratiometric fluorescent peptidyl probe (1) by conjugation of a peptide receptor for Pb(II) with an excimer-forming benzothiazolylcyanovinylene fluorophore. The peptidyl probe dissolved well in aqueous solution and displayed an emission band at 538 nm (λ ex = 460 nm). Upon addition of Pb(II) (0-20 μM), the emission maximum shifted from 538 nm to 575 nm and the emission intensity ratio (I 575 /I 538 ) increased significantly from 0.40 to 2.26. 1 exhibited a selective ratiometric response to Pb(II) over other metal ions. 1 with a low detection limit (1.2 ppb) of Pb(II) detected nanomolar concentrations (0-500 nM) of Pb(II) ions in groundwater and tap water. The cell-permeable probe detected intracellular Pb(II) by ratiometric fluorescent images. The binding mode study using NMR, IR and CD spectroscopy, and TEM revealed that the probe formed a 1:1 complex with Pb(II) and then formed red-emissive nanoparticles and fibrils. The probe exhibited desirable detection properties such as ratiometric detection, high solubility in water, visible light excitation, high selectivity and sensitivity for Pb(II), cell-permeability, and rapid response (< 6 min)., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The design and development of materials with a selective adsorption capacity for Pb(II) are very important for environmental governance and ecological safety. In this work, a novel 3D metal-organic framework ([Cd 2 H 4 L 4 Cl 2 SO 4 ]·4H 2 O, Cd-MOF) is constructed using a multiple pyrazole heterocycles tetraphenylethylene-based ligand (H 4 L 4 ) and CdSO 4 which containing Pb(II) adsorption sites (SO 4 ). Studies have shown that the Cd-MOF has outstanding stability, and its maximum adsorption value of Pb(II) can be as high as 845.55 mg/g, which is higher than that of most MOFs or MOFs modified materials. It is worth emphasizing that the Cd-MOF have excellent recyclability due to the unique adsorption mechanism of the Cd-MOF. Thermodynamic studies have shown that Pb(II) adsorption of the Cd-MOF is a spontaneous endothermic process. Specific selective adsorption, exceptional stability and remarkable recyclability make the Cd-MOF a potential material for industrial capture and recovery of Pb(II) from water.2- ). Studies have shown that the Cd-MOF has outstanding stability, and its maximum adsorption value of Pb(II) can be as high as 845.55 mg/g, which is higher than that of most MOFs or MOFs modified materials. It is worth emphasizing that the Cd-MOF have excellent recyclability due to the unique adsorption mechanism of the Cd-MOF. Thermodynamic studies have shown that Pb(II) adsorption of the Cd-MOF is a spontaneous endothermic process. Specific selective adsorption, exceptional stability and remarkable recyclability make the Cd-MOF a potential material for industrial capture and recovery of Pb(II) from water., (Copyright © 2021 Elsevier B.V. All rights reserved.)

For the first time, functionalized asphaltene has been designed, synthesized, and used for the removal of heavy metals from the water. Asphaltene was separated from the crude oil with the addition of n-alkanes. Asphaltene having a complex chemical structure including multilayered and clustered aromatic fused rings bearing aliphatic chains. Asphaltene also contains heteroatoms like N, S, and O atoms along with Ni and V as prominent trace metals. On functionalization of asphaltene with nitric acid, the aliphatic chains and some of the naphthenic rings broke down and developed -COOH, -CO, C-O, and other oxygen functional groups which are playing key roles as surface-active agents in the removal of the heavy metals via chemisorption. The study was conducted using different parameters such as dose, time, pH, and concentration. The adsorption efficiency for this material at pH 4 is excellent for the removal of chromium and lead. The Langmuir, Freundlich and Temkin adsorption isotherm models as well as Lagergren pseudo second-order kinetic model were investigated. The positive enthalpies ΔHs confirm that the adsorption process is endothermic and the negative free energies ΔGs confirm the spontaneity of the process. The good efficiency of the adsorption implies the efficacy in the removal of the heavy metal ions, as well as the good efficiency in desorption, which implies the excellent recovery of the adsorbent. The effective reusability of this adsorbent makes it applicable for industrial water treatment from contaminants., (Copyright © 2021. Published by Elsevier Inc.)

Bioremediation by phosphate-solubilizing bacteria (PSB) has attracted extensive attentions due to its economical and eco-friendly properties for lead (Pb) passivation in soil. Herein, bone char (BC) supported biochemical composite (CFB 1 -P) carrying advantages of BC, PSB, iron sulfide (FeS) and carboxymethyl cellulose (CMC) was designed and applied to Pb passivation. The composite at a mass ratio of BC:CMC:FeS = 1:1:1 possessed high passivation efficiency (65.47%), and has been demonstrated to offer appropriate habitat environment for PSB to defend against Pb(II) toxicity, thus enhancing the phosphate-solubilizing amount of PSB to 140.72 mg/L for passivating Pb(II). Batch experiments showed that the CFB 1 -P possessed excellent adsorption properties with maximal monolayer Pb(II) uptake of 452.99 mg/g during an extensive pH range of 2.0-6.0. Furthermore, by applying CFB 1 -P dosage of 3% into Pb-contaminated soil, the labile Pb fractions were reduced from 29.05% to 6.47% after simulated remediation of 10 days, and converted into steady fractions. The CFB 1 -P was demonstrated to achieve high Pb(II) passivation through combined functions of chemical precipitation, complexation, electrostatic attraction and biomineralization, accompanied by the formation of more stable crystal structures, for instance, Pb 5 (PO 4 ) 3 OH, Pb 3 (PO 4 ) 2 and PbS. These results suggested CFB 1 -P as a potential alternative for efficient remediation of Pb-contaminated soil., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this study, Chlorella sorokiniana FK, isolated from lead-zinc tailings, was employed for Pb(II) biomineralization with or without montmorillonite (MMT) addition in soil. Batch experiment results showed that montmorillonite facilitated Pb 3 (CO 3 ) 2 (OH) 2 formation on the surface of Chlorella-MMT composite, thus increasing algal cells' tolerance to Pb(II) poisoning. Surprisingly, Pb(II) adsorbed and biomineralized by Chlorella-MMT composite was 2.69 times and 3.76 times as much as that by Chlorella alone, respectively. The montmorillonite facilitated Chlorella-induced Pb biomineralization by promoting both photosynthesis and urea hydrolysis, mainly due to more hydroxyl functional groups generated during its binding with Chlorella and its high pH buffering capacity. Moreover, the SEM-EDS analysis indicated that the biomineral particles shifted from algal cell surface to montmorillonite surface in the composite during long-term Pb-detoxification. In-situ soil Pb(II) remediation experiments with Chlorella-MMT composites further showed that Pb was immobilized as carbonate form in the short term and as residue fraction in the long term. This study made the first attempt to explore the facilitating effects of montmorillonite on metal-carbonate precipitation mediated by microalgae and to develop a green, sustainable, and effective strategy for immobilization of heavy metal in soil by combining clay minerals and microalgae., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this study, a novel electrochemical sensor for simultaneous detection of Pb(II) and Cu(II) was constructed by using Zn/Ni-ZIF-8/XC-72/Nafion hybrid material as electrode surface modifier. XRD, FT-IR, XPS and SEM were used to study the crystal structure, functional groups, element types and morphologies of the prepared materials. The electrochemical performance of the Zn/Ni-ZIF-8/XC-72/Nafion/GCE sensor were investigated by CV, EIS and DPV. In addition, the effects of various conditions including pH, the type of buffer and the ratio of Zn/Ni-ZIF-8 to XC-72 were also explored for the determination of Pb(II) and Cu(II). Under the optimum conditions, the constructed sensor exhibited outstanding linear response of Pb(II) (0.794-39.6 ppm) and Cu(II) (0.397-19.9 ppm) with detection limits of 0.0150 and 0.0096 ppm, respectively. Finally, the fabricated sensor was further used to detect Pb(II) and Cu(II) in real samples, and the satisfactory recovery was obtained., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Heavy metals and endocrine disrupters often co-exist in wastewater, while their possible competition behaviours make uptake removal more challenging. Therefore, β-Cyclodextrin based nanocomposite adsorbent was successfully fabricated (β-Cyclodextrin/ZrO 2 ) for the simultaneous uptake of Pb(II) and Bisphenol A from wastewater. FTIR, XRD, and XPS confirmed the successful fabrication of the β-Cyclodextrin/ZrO 2 nanocomposite. In this setting, oxygen-containing groups are primarily responsible for the Pb(II) binding, while the β-Cyclodextrin cavities adsorb Bisphenol A through host-guest interaction, enabling the simultaneous removal of Pb(II) and Bisphenol A. In the mono contaminant system, the nanocomposite displayed prominent removal ability toward Pb(II) and Bisphenol A with adsorption characteristics of pseudo-second-order, Langmuir, and Freundlich isotherm model. The maximum adsorption capacities were identified for Pb(II) and Bisphenol A to be 274.4 mg/g and 174.9 mg/g at 298 K, respectively. Most importantly, the β-Cyclodextrin/ZrO 2 could efficiently attain simultaneous removal of Pb(II) and Bisphenol A by avoiding their competitive behaviours was due to the different adsorption mechanisms (electrostatic interaction and host-guest interaction). Moreover, the adsorbed Pb(II) and Bisphenol A could be successfully recovered with a slight decline in nanocomposite removal performance even after 4 cycles in the binary-component system. All these findings provide insights into the fabrication of highly effective adsorbent with separated adsorption sites to treat wastewater bearing heavy metal and endocrine disrupters., 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.)

Fruitful achievements on electrochemical detection toward Pb(II) have been achieved, and their good performance is generally attributed to the adsorption property of nanomaterials. However, the design of sensing interfaces from the electronic structure and electron transfer process is limited. Here, Co@Co 3 O 4 acquired an ultra-high detection sensitivity of 103.11 µA µM -1 toward Pb(II), outperforming the results previously reported. The interfacial oxygen atoms build an electron bridge for Co activating Co 3 O 4 . Particularly, new energy levels of oxygen atoms were generated and matched with that of Pb(II). The strong orbital coupling effect between O and Pb makes the Co@Co 3 O 4 sensitive and selective toward Pb(II). Compared with Co metal and Co 3 O 4 , Pb(II) got more electrons from Co@Co 3 O 4 , and longer Pb-O bonds were formed, allowing more Pb(II) to be catalyzed and reduced. Also, the superior stability and reproducibility of electrochemical detection make electrodes practicably. This work reveals that metals can stimulate intrinsically catalytic activity of their metal oxides, with the generation of orbit energy levels that match to a specific analyte. It provides a promising strategy for constructing sensitive and selective sensing interfaces toward ultra-low concentration analyte in body fluid and other complex samples., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A novel metal-organic framework (UiO-66-PTC) for efficient removal of Pb 2+ ions from wastewater has been prepared by using 4-phenyl-3-thiosemicarbazide as the modifier. Various characterizations showed that UiO-66-PTC was successfully synthesized. The absorption results showed that the maximum adsorption capacity of Pb(II) is 200.17 mg/g at 303 K and optimal pH 5. The adsorption kinetic follows the pseudo-second-order model and the adsorption isotherms fit the Langmuir model. This shows that Pb(II) is a single-layer adsorption on the surface of the adsorbent and the rate-controlling step is chemical adsorption. The thermodynamic results show that the adsorption process can proceed spontaneously, belong to the exothermic reaction. The adsorbent can selectively uptake lead ions from wastewater containing multiple interfering ions. After four adsorption and desorption cycles, the adsorption efficiency is still high. The adsorption mechanism of Pb(II) on the adsorbent is mainly through the chelation of Pb(II) with N and S atoms. These results indicate that UiO-66-PTC is an effective material for efficiently and selectivity removal of Pb(II) from solution, which is of practical significance., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Mining is the most common activity that introduces heavy metal ions into aquatic ecosystems, especially in low income-developing nations where governments are implementing stricter regulations for industrial wastewater. In this context, this work is focused on the application of xanthate-modified alginates for the removal of Pb(II) and Ni(II) from aqueous solutions. In order to confirm the presence of xanthate groups alongside alginate chains, characterization by second-derivative FT-IR was carried out and significance evidence attributed to xanthate groups was found at around 1062-1079 cm -1 , 829-845 cm -1 and 620-602 cm -1 . In addition to this, thermogravimetric analysis and differential scanning calorimetry were employed to explore thermal properties of modified alginates. According to these results, enthalpy changes (∆H) characteristic of dehydration and collapse of biopolymeric structure were estimated as +11.41 J/g and -6.83 J/g, respectively. Furthermore, the presence of S element was confirmed by EDS mapping technique, whereas FESEM image showed a cracked and homogeneous surface distribution. On the other hand, the effect of important parameters such as pH, dosage, initial concentration as well as Langmuir and Freundlich isotherm were deeply discussed. Finally, rheological measurements were performed aiming to investigate the gel-like viscoelastic features associated to nickel xanthate compound., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A chitosan-based adsorbents (CS-Ninhydrin) was prepared by grafting ninhydrin for Pb(II) ions adsorption. SEM-EDS, XRD and FTIR analysis were used to characterize the synthesized CS-Ninhydrin. The static adsorption experiments showed that CS-Ninhydrin had a good removal rate for Pb(II) ions in a wide range of pH 3 to 7, quickly reached equilibrium (120 min) and had a higher adsorption capacity (196 mg/g). Pseudo second-order and Langmuir models showed that the adsorption process of Pb(II) by CS-Ninhydrin was a single-layer chemical adsorption. Temperature experiments showed that the reaction was a spontaneous exothermic process. In the wastewater experiment, CS-Ninhydrin showed an excellent selectivity to Pb(II) ions. The reusability of CS-Ninhydrin was perfect after five adsorption-desorption cycles. The main adsorption mechanism was the chelating and electrostatic action between N and O groups in CS-Ninhydrin and Pb(II) ions. Therefore, the new adsorbent CS-Ninhydrin was expected to promote the wide application of chitosan in Pb(II) adsorption., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel bifunctional oligonucleotide (OND) probe with single fluorescent group HEX labelled at 5'-end was designed for detecting trace Ag(I) and Pb(II) in real samples. In the presence of Ag(I), the hairpin structure originating from Ag(I) induced cytosine-Ag(I)-cytosine mismatches causes the proximity of the HEX to the consecutive guanine bases (G) 4  at 3'-terminal, resulting in the fluorescence quenching of the HEX. While in the presence of Pb(II), the G-quadruplex structure originating from two G-quartet planes by the intramolecular hydrogen bond with Pb(II) also causes the HEX approaching the (G) 4 terminal and consequently the fluorescence quenching. The results showed the quantitative detection of trace Ag(I) and Pb(II) both in the linear response ranges of 1.0-20.0 × 10 -9  mol L -1 with no visible interferences of other 11 metal ions observed. And the detection limits were 82 × 10 -12  mol L -1 for Ag(I), 92 × 10 -12  mol L -1 for Pb(II), respectively. The fluorescence quenching mechanism of the (G) 4 to HEX was verified to be the photoinduced electron transfer in the aspect of thermodynamics. This method provided a feasible application for sensitive and selective detection of Pb(II) and Ag(I) in water and Chinese traditional herbs with convenient operation., 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.)

Lead contamination in drinking and natural water has reached alarming concentrations, thus necessitating the development of accurate and rapid determination systems for Pb(II) in aqueous systems. Two hyphenated flow injection-solid phase extraction- FAAS (FI-SPE-FAAS) systems using oxidized and m-phenylenediamine functionalized multiwalled carbon nanotubes for Pb(II) preconcentration from industrially contaminated real water samples have been proposed. The chemical and hydrodynamic parameters affecting Pb(II) sorption/desorption were optimized. The effect of common interfering ions in water was also studied. Different figures of merit such as preconcentration factor (> 70), detection limit (≤ 1.5 µg L -1 ), and relative standard deviation (≤ 1.3%) were achieved at the preconcentration time of 120 s for both the preconcentration systems. The method was applied to industrially contaminated real water samples and the spike recovery tests were carried out using standard Pb(II) solution traceable to NIST. The proposed method was validated using standard reference material 1640a supplied by NIST Gaithersburg, MD, USA., 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. Published by Elsevier B.V.)

Herein, β-cyclodextrin (β-CD) was efficiently grafted onto rice husk-based celluloses using different cross-linking agents of epichlorohydrin (EPI) and glutaraldehyde (GA). By feat of microwave irradiation, the functionalization procedure was completed in 17 min, and the synthesized RHEPIMWβ-CD and RHGAMWβ-CD exhibited fast adsorption equilibrium for Pb(II) within 20 min, excellent monolayer adsorption capacities of 216.06 and 279.08 mg g -1 across an extensive pH scope of 3.0-6.0, unaffected affinity to Pb(II) during the existence of co-existing ions, superior reusability with over 81% and 87% of Pb(II) uptake sustained for four adsorption-desorption cycles. Thermodynamic parameters implied that the uptake process of Pb(II) occurred spontaneously (-ΔG 0 ) with an endothermic characteristic (+ΔH 0 ). Furthermore, electrostatic attraction and complexation were demonstrated to enhance the Pb(II) uptake onto the RHEPIMWβ-CD and RHGAMWβ-CD. In fix-bed columns, these two adsorbents also efficiently eliminated Pb(II) under various flow rates with experimental breakthrough curves well simulated by Thomas and Yoon-Nelson models. Significantly, the RHEPIMWβ-CD and RHGAMWβ-CD could effectively purify acid battery effluent containing Pb(II) for meeting regulatory requirement. Overall, the fast fabrication, excellent adsorption and recycling performance facilitate the development of tailored adsorbents for Pb(II) elimination in 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 © 2020 Elsevier B.V. All rights reserved.)

In this study, batch and spectroscopic approaches were used to explore the sorption of Pb(II) on micas (i.e., muscovite, biotite and phlogopite) in the presence of Trichoderma viride (T. viride). Batch sorption showed that ion exchange, outer-sphere complexes (OSCs) and inner-sphere complexes (ISCs) contributed to Pb(II) sorption on biotite and phlogopite in the pH range of 2.0-7.4, whereas the ISCs were predominant for Pb(II) sorption on muscovite. X-ray diffraction and Fourier transform infrared (FT-IR) analyses have confirmed the changes of structure and surface properties of micas after co-culturing with T. viride, which could improve the sorption capacity of micas to Pb(II). Scanning electron microscopy revealed the bio-mineralization of Pb(II) on T. viride and mica-T. viride composites forming lead phosphates. Furthermore, FT-IR analysis showed that the groups of Si-OH, Al-OH from micas, and carboxyl, phosphate and amino groups from T. viride were synergistically contributing to Pb(II) sorption on mica-T. viride composite. X-ray photoelectron spectroscopy further confirmed that both OSCs and ISCs formed for Pb(II) sorption on micas; however, in the case of mica-T. viride composites, the synergistic effects of T. viride and micas were contributing to Pb(II) sorption through forming the ISCs and biomineralization., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Heavy metals and pesticides often coexist in contaminated water, while their potential competition behaviors make the adsorptive removal more challenging. Thus, decorating an adsorbent with independent functional sites could be a promising alternative to radically prevent the competitive process for improving the adsorption performance. Herein, β-cyclodextrin functionalized rice husk-based cellulose (β-CD@RH-C) was designed and applied for synchronous removal of atrazine and Pb(II). The characterization results supported the successful grafting of β-cyclodextrin onto the cellulose. The β-CD@RH-C presented a pH-dependent adsorption performance for Pb(II) with a theoretical monolayer adsorption capacity of 283.00 mg/g, while was mostly unrelated to pH for atrazine adsorption with a heterogeneous uptake of 162.21 mg/g in the mono-component system. Most importantly, the β-CD@RH-C could efficiently achieve simultaneous removal of atrazine and Pb(II) via avoiding their competitive behaviors, which was due to the different adsorption mechanisms for atrazine (i.e. host-guest interaction) and Pb(II) (i.e. complexation and electrostatic interaction). Moreover, the adsorbed atrazine and Pb(II) could be sequentially desorbed with slight decrease in the adsorption performance of β-CD@RH-C even after four cycles in the atrazine-Pb(II) multi-component system. All these results suggested β-CD@RH-C to be a tailored adsorbent with high-performance elimination of co-existing heavy metals and organic pollutants in water., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, nano-silica (Nano-SiO 2 ), oxidized (O-CNTs) and graphitized multi-walled carbon nanotubes (G-CNTs) were applied as model adsorbents to study the adsorption, desorption and coadsorption behaviors of sulfamerazine (SMR), Pb(II) and benzoic acid (BA). The results showed that charge assisted H-bond (CAHB) formation played an important role in adsorption of SMR and BA on O-riched nanomaterials. The adsorption capacities of Pb(II) on CNTs were 21.46- 26.77 times higher than that on Nano-SiO 2 , which was mainly attributed to surface complexation and cation-π interaction. The fraction of Pb 2+ adsorbed in the inside channel of CNTs should not be ignored. In coexisting systems, the absolute sorption inhibition of the SMR (ΔQ e ) was compared with the amount of competitor adsorbed. Competitive sorption was observed as indicated by adding Pb(II) decreased adsorption of SMR on Nano-SiO SMR ) was compared with the amount of competitor adsorbed. Competitive sorption was observed as indicated by adding Pb(II) decreased adsorption of SMR on Nano-SiO 2 (ΔQ e SMR  > 0), but hardly affected SMR adsorption on CNTs (ΔQ e SMR  ≈ 3.15), which also consequently resulted in stronger competition of Pb(II) to SMR on Nano-SiO 2 (ΔpK a  ≈ 4.34) was weaker than that formed between SMR and O-CNTs (ΔpK a  ≈ 3.15), which also consequently resulted in stronger competition of Pb(II) to SMR on Nano-SiO 2 than that on O-CNTs. Moreover, coexisting BA increased adsorption of SMR on Nano-SiO 2 and G-CNTs (ΔQ e SMR  < 0), but did not result in an apparent competition on SMR adsorption by O-CNTs (ΔQ e SMR  ≈ 0). These results emphasize that the environmental behaviors of a certain pollutant should be assessed carefully by considering the presence of other pollutants., 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 There is no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Urea formaldehyde (UF) was grafted onto the backbone of alginate to prepare microbeads as an adsorbent for the removal of heavy metal ions from aqueous solutions. The expensive alginate was crosslinked with cheaper UF at different ratios (1: 2.5∼1: 12.5) to produce sturdy alginate-UF beads at lower cost. Characterization results showed that UF modification enhanced the pore network and structural stability of the beads, which can be attributed to the reduced intermolecular forces and plentiful of nitrogen and oxygen donor atoms of the beads. The swelling of air-dried alginate-UF beads in different solutions was much lower than that of the unmodified alginate beads, confirming the improved stability. The replacement of alginate with UF at different ratios either did not affect or increased the adsorption of heavy metal ions (Pb 2+ , Cd 2+ , and Cu 2+ ) on the beads. For example, the adsorption capacities of Pb 2+ , Cd 2+ , and Cu 2+ on air-dried alginate-UF (1: 2.5) beads were 1.66, 0.61, and 0.80 mmol/g, which were 39.88%, 9.29%, and 9.52% higher than those of the corresponding unmodified alginate beads, respectively. The adsorption of heavy metals on the alginate-UF beads was mainly controlled by ion exchange, complexation, and electrostatic interaction mechanisms., 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 © 2020 Elsevier B.V. All rights reserved.)

In this study, the adsorption behaviors and mechanisms of Pb(II) and Zn(II) by animal-derived biochar (ADB) in single and binary metal systems were comparatively investigated. ADB contains considerable amounts of Ca/P components and is mainly composed of hydroxyapatite (HAP), which plays an important role in the adsorption of Pb(II) and Zn(II). The maximum adsorption capacities of Pb(II) and Zn(II) on ADB were in the order of Zn(II)-single (3.23 mmol g - ) > Pb(II)-single (2.74 mmol g 1 ) ≈ Pb(II)-binary (2.71 mmol g - 1 ). In the single metal system, approximately 99.9% of the adsorbed Pb(II) existed as Pb - 1 ) > Zn(II)-binary (2.31 mmol g - Cl, while the dominant adsorption mechanism of Zn(II) was cation exchange, followed by precipitation, accounting for 78.0%-80.6% and 19.4%-21.5% of the adsorption capacity, respectively. These findings were verified by X-ray diffraction refinement, X-ray photoelectron spectroscopy, metal speciation modeling, and Ca(II) exchange experiment. In the binary metal system, the proportion and form of Pb(II) precipitate remained unchanged. However, the binding of Zn(II) to ADB was completely dependent on the cation exchange with Ca(II), and no remarkable Zn(II) precipitation was observed. Phosphate released from HAP preferentially precipitated with Pb(II) than with Zn(II) when they coexisted. Consequently, Pb(II) competition may alter the Zn(II) adsorption mechanism on ADB. Nonetheless, ADB could serve as an efficient biochar for the simultaneous immobilization of Pb(II) and Zn(II) via different mechanisms.1 ). In the single metal system, approximately 99.9% of the adsorbed Pb(II) existed as Pb 5 (PO 4 ) 3 Cl, while the dominant adsorption mechanism of Zn(II) was cation exchange, followed by precipitation, accounting for 78.0%-80.6% and 19.4%-21.5% of the adsorption capacity, respectively. These findings were verified by X-ray diffraction refinement, X-ray photoelectron spectroscopy, metal speciation modeling, and Ca(II) exchange experiment. In the binary metal system, the proportion and form of Pb(II) precipitate remained unchanged. However, the binding of Zn(II) to ADB was completely dependent on the cation exchange with Ca(II), and no remarkable Zn(II) precipitation was observed. Phosphate released from HAP preferentially precipitated with Pb(II) than with Zn(II) when they coexisted. Consequently, Pb(II) competition may alter the Zn(II) adsorption mechanism on ADB. Nonetheless, ADB could serve as an efficient biochar for the simultaneous immobilization of Pb(II) and Zn(II) via different mechanisms., 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 © 2020 Elsevier B.V. All rights reserved.)

The application of graphene oxide (GO) and its derivatives as adsorbents to remove heavy metal contaminants from industrial wastewaters has attracted increasing attention worldwide. Here, we investigated the role of oxidative debris (OD) on GO surfaces in the adsorption of Pb(II) under natural conditions. OD attached to GO surfaces can be removed under alkaline conditions, and plays a critical role in the adsorption of Pb(II) by GO. Specifically, the maximum adsorption capacity of Pb(II) on GO decreased from 926.50 to 357.64 mg·g -1 after OD removal. Under simulated natural alkaline groundwater conditions, some adsorbed Pb(II) was released with OD that was stripped from spent GO adsorbents (i.e., GO-Pb(II)). Further, batch experiments indicated that 1.30-1.43% of adsorbed Pb(II) could stably disperse in water as dissolved PbCO 3 and OD-Pb(II) complexes, at a pH of ~8.3. The stripping and dissociation of OD under alkaline conditions promoted the mobility of Pb(II) on GO adsorbents. This study enhances our understanding of heavy metal transport in natural alkaline groundwater environments that contain GO particles., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The development of high efficiency filter membranes, particularly those capable of removing trace heavy metals from drinking water sources, is a global challenge. In this study, a dual-functional membrane (P m G n @PVDF) was successfully developed by doping graphene oxide (GO) and then depositing polydopamine (PDA). The pure water flux (Jw) was 188 LMH/bar and Pb(II) could be effectively removed in the water volume of 2106.36 L m -2 . Both PDA and GO performed positive functions. PDA layer exhibited a high affinity toward Pb(II) by chelating with amino groups. And doping GO maintained a high pure water flux, which had been decreased by the extra PDA layer. In addition, the effective treatment volume of Pb(II) was elevated to 5029.06 L/m 2 by the co-existence of citric acid, since neutral PbHL coordinated with neutral NH 2 and cationic PbL- interacted with NH 3 + through electrostatic attraction. Furthermore, P m G n @PVDF showed the excellent anti-interference performance in high salt and nature organic matters solutions. Thus, this novel dual-functional membrane could be considered as a competitive alternative of NF/RO for the efficient and advanced removal towards heavy metals from natural water., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study investigated the treatment performance of activated sludge on Pb(II)-containing wastewater, including contaminant removal efficiency, extracellular polymeric substances, pbrT gene content and the microbial community. The average removal efficiencies of ammonia nitrogen, chemical oxygen demand, total phosphorus, total nitrogen and Pb(II) were 40% ± 4%, 91% ± 3%, 95% ± 3%, 51% ± 5% and 92% ± 9% during the stable operation stage, respectively. Moreover, the extracellular polymeric substance -protein contents increased significantly from day 0 to day 60 (p < 0.05). The most abundant fluorescent component in extracellular polymeric substances was a humic acid-like substance, and its fluorescence intensity increased significantly from day 0 to day 60 (p < 0.05). Adsorption of negatively charged organic functional groups in extracellular polymeric substances was identified as a major component of the removal of Pb(II). Most of the denitrifying bacteria associated with nitrogen removal showed an increasing trend during the acclimation stage, which may have resulted in high total nitrogen removal efficiency. In addition, pbrT uptake protein was found to be responsible for the uptake of Pb(II) into cells. The abundance of the pbrT gene showed a downward trend (p < 0.05) after adding Pb(II), probably because expression of the pbrT gene was inhibited under Pb(II) stress. Sphingopyxis containing the pbrT gene was the dominant resistance genus, and its relative abundance increased significantly (p < 0.05) from day 0 to day 60. This study provided a theoretical basis for the treatment of Pb(II)-containing wastewater., (Copyright © 2019 Elsevier B.V. All rights reserved.)