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The presence of poisonous Pb(II) ions in water resources has raised global health concerns. Herein, the adsorption performance of accordion‐like Ti3CN MXene for Pb(II) ions was investigated for the first time. Batch experiments were carried out by varying modifications, pH values, initial Pb(II) concentrations, adsorption time and temperatures. The results prove that the alkalized‐Ti3CN shows enhanced adsorption performance. Although the temperature effect is insignificant, the Pb(II) adsorption is strongly pH‐dependent. The maximum Pb(II) adsorption capacity of alkalized −Ti3CN is about 2.5 times higher than that of activated carbon. The adsorption ratio of Pb(II) is up to 96.6 %. The adsorption capacity increases with increasing the initial concentration of Pb(II). The alkalized‐Ti3CN adsorbs Pb(II) very quickly and the adsorption equilibrium is nearly achieved within 70 minutes. The adsorption follows the quasi‐second‐order kinetic model as well as the Langmuir model, and is mainly controlled by chemical adsorption. It is preliminarily concluded that Pb(II) replaces Na(I) of the −ONa functional groups on the alkalized‐Ti3CN surfaces. This study proves the alkalized‐Ti3CN MXene has potential application for the purification treatment of wastewater contaminated with Pb(II) ions. [ABSTRACT FROM AUTHOR]

In the present study, highly porous composite material (PCM) was fabricated by novel ligand immobilization onto the silica monolith for Pb(II) ion detection and adsorption from wastewater by the solid-liquid separation method. The material was systematically characterized to know the material morphology and functional group. In addition, the Pb(II) capturing performance of PCM toward Pb(II) in aqueous media was explored. The PCM was enhanced the color upon addition of different concentration Pb(II) ion. The low-level limit detection was determined, and the value was 0.33 μg/L, which was lower than the permissible limit of Pb(II) ion in water. Factors affecting the adsorption of Pb(II) ion such as solution acidity, reaction time, initial Pb(II) concentration, competing ion and regeneration were investigated systematically in batch mode by the PCM. The solution pH was played the key role both in the detection and adsorption of Pb(II) ion. The pH dependent was exhibited due to the complexation bonding ability. The kinetic performance was rapid as the Pb(II) ion adsorption was equilibrated within short time, and this was confirmed the chemisorption process. The adsorption isotherm of Pb(II) onto PCM was well fitted to the Langmuir isotherm models as expected from the material homogeneity. In addition, the maximum monolayer adsorption capacity was 204.34 mg/g. The competing ions were not affected the Pb(II) detection or adsorption, and this were evident to the high selectivity toward the Pb(II) ion at the optimum condition. The adsorbed Pb(II) from PCM was desorbed with 0.15 M HCl and then simultaneously regenerated for next Pb(II) capturing process. Therefore, the proposed PCM can be considered as a potential material for Pb(II) ion detection and adsorption from the wastewater sample. Unlabelled Image • Soft donor ligand was prepared and then fabricated the composite material (PCM). • The PCM was exhibited the high sensitivity and selectivity toward the Pb(II) ion. • The PCM is cost-effective and environmentally friendly for Pb(II) ion capturing. [ABSTRACT FROM AUTHOR]

A novel adsorbent, composed of cross-linked de-esterified pectin microspheres, was prepared via cross-linking with Ca(II) and modification by de-esterified pectin, low-methoxyl pectin (LMP) and pectic acid (PA). Fourier transform infrared (FTIR), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and atomic absorption spectroscopy (AAS) were applied too, exhibiting a successful fabrication, good adsorption ability, and well-defined surface microstructure beneficial to Pb(II) adsorption. The adsorption ability of pectin microspheres (PMs), low-methoxyl pectin microspheres (LMPMs) and pectic acid microspheres (PAMs) for Pb(II) in aqueous solution were explored. The maximum adsorption capacity of PMs, LMPMs and PAMs was 127 mg·g-1, 292 mg·g-1 and 325 mg·g-1 at pH 5.0 respectively, indicating a great improvement of LMPMs and PAMs in the adsorption ability for Pb(II) compared with PMs. Furthermore, the adsorption mechanism was proposed. The experimental data were well fitted with pseudo-second-order kinetic and Langmuir isotherm models. Five-cycle reusability tests demonstrated that microspheres could be used repeatedly. All the results confirmed that LMPMs and PAMs, which presented outstanding adsorption capability and reusability, could be a good candidate for wastewater purification. [ABSTRACT FROM AUTHOR]

Abstract Pistachio wood-derived activated carbon prepared by a two-stage process (PWAC-2), conducting two consecutive chemical activation processes with NH 4 NO 3 and NaOH, respectively. The results showed that explosive characteristic of NH 4 NO 3 can primarily be employed to produce a char, with a large surface area and a highly-ordered pore structure, which can be subjected to a second activation process with NaOH to prepare a more suitable activated carbon, with a highly porous structure and useful functional groups, for removal of lead ions from aqueous media. An L 25 Taguchi experimental design was used by varying impregnation ratio, activation time and temperature in both pre- and post-activation stages, and the results showed that, in both stages, a small activating agent/precursor and a proportional low activation time suffice for preparation of an advantageous activated carbon for Pb(II) adsorption. A comprehensive study was performed on the equilibrium, kinetic and thermodynamic aspects of Pb(II) adsorption by the new activated carbon. The results exhibited that, having had a high lead adsorption capacity (190.2 mg g−1), a high adsorption rapidness, and thermodynamic favorability, PWAC-2 is a beneficial alternative for utilization in full-scale plants of lead removal from waters and wastewaters. Highlights • Suitable activated carbon for Pb(II) removal was produced by two-stage activation process. • NH 4 NO 3 and NaOH were, respectively, used as pre- and pro-activation agents. • A small activating agent/precursor and a low activation time were enough for activation. • Explosive characteristic of NH 4 NO 3 resulted in a char with a highly-ordered pore structure. • NaOH as pro-activating agent raised the activated carbon efficiency for Pb(II) sorption. [ABSTRACT FROM AUTHOR]

Graphical abstract An efficient surface Pb(Ⅱ) ion-imprinted polymer based on sandwich-like graphene oxide composite materials (GO-IIP) was synthesized and successfully applied to the selective removal of trace lead ions. The material selectively adsorbs Pb(Ⅱ) from the aqueous solution due to the cavities in polymers, where the complexing ligands are arranged so as to match the charge, coordination number, coordination geometry and size of lead ions. Abstract An efficient surface Pb(Ⅱ) ion-imprinted polymer based on sandwich-like graphene oxide composite materials (GO-IIP) was synthesized and characterized for studying the morphology and adsorption properties. Effects of preparation and adsorption conditions including solvent type, molar ratio of functional monomer to crosslinking agent, initiator dosage, pH, adsorbent dosage, contact time, ions concentration on the Pb(Ⅱ) removal were studied. Adsorption equilibrium was reached within 30 min and the adsorption process followed pseudo-second-order kinetic and Langmuir adsorption isotherm models, indicating chemisorption was the rate-limiting step. The maximum adsorption capacity of Pb(Ⅱ) ion-imprinted polymer was as high as 40.02 mg g−1 at 25 ℃, which was much higher than that of the non-imprinted polymer (20.45 mg g−1). The selectivity coefficient of Pb / Zn, Pb / Cd, Pb / Co, Pb / Ni and Pb / Ca were 20.12, 14.26, 31.67, 25.65 and 81.29, respectively, further confirming the satisfactory selectivity of GO-IIP. In addition, the prepared adsorbent could be reused 5 times without significant reduction of the adsorption capacity. Furthermore, an XPS spectra analysis was successfully applied to exploring the possible adsorption mechanism between Pb(Ⅱ) and GO-IIP, indicating that nitrogen atom in the amide bond of the functional monomer was the main coordination atom. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The development of a high-efficiency adsorption material is important for the simultaneous elimination of heavy metal ions and organic pollutants from wastewater. In the present work, a novel material was synthesized by grafting functionalized cucurbit [8] uril (CB[8]) onto chitosan (CS) chains via a C N C covalent bond (CB[8]-CS). This as-prepared material presented an unprecedented adsorption capacity. The maximum adsorption capacities (q m) were 1622.7 mg/g, 1172.7 mg/g, 1361.9 mg/g and 873.6 mg/g for the adsorption of reactive orange 5 (RO5), acidic blue 25 (AB25), reactive yellow 145 (RY145) and Pb2+ ions, respectively, which are far higher than the reported data. The simultaneous co-adsorption of dye and a heavy metal ion was tested with a mixed solution of 200 mg/L RO5 dye and Pb2+ ion, and the removal rates were 97% and 70% for RO5 and Pb2+, respectively. The adsorption mechanism was explored by means of the IR spectrum and the UV–vis diffuse reflection spectrum (DRS) together with theoretical calculations. The adsorption of dyes was mainly driven by the strong interaction between dye molecules and the hydrophobic cavity of CB[8], and the Pb2+ adsorption was mainly driven by the coordination of Pb2+ with the carbonyl of the CB[8] port and the amino group of chitosan. The ultrahigh adsorption capacity allows the use of CB[8]-CS as potential adsorbent for the simultaneous removal of heavy metal ions and organic dyes from aqueous solution. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The removal of Pb(II) from wastewater by graphene oxide (GO) using foam flotation was first investigated. Effects of initial solution pH, and the dosage of GO, emulsified kerosene and terpenic oil on the Pb(II) removal and turbidity of the residual solution were systematically examined. The experimental results showed that the initial solution pH and dosage of GO significantly affected the removal of Pb(II), and more than 99% of Pb(II) could be removed under the optimum conditions. The turbidity of the residual solution could decrease to 1.4 NTU at the optimal dosage of emulsified kerosene and terpenic oil. Moreover, the flotation-desorption cycles were carried out to evaluate the practical reusability of GO, and the Pb(II) removal maintained as high as 84.9% in the sixth regeneration. It indicated that GO could be efficiently reused in the process of foam flotation. This study provides an effective strategy for the selection of an optimized method to remove the spent GO from solution compared with the conventional methods including sedimentation, centrifugation and filtration, etc. [ABSTRACT FROM AUTHOR]

Herein, the manganese-oxides-coated magnetic microcrystalline cellulose (MnOx@Fe 3 O 4 @MCC) was prepared by coprecipitation and subsequently modified with KMnO 4 solution at room temperature, which was in turn applied for the removal of Pb(II) from wastewater. The adsorption properties of Pb(II) on MnOx@Fe 3 O 4 @MCC were investigated. The kinetics and isothermal data of Pb(II) were described well by the Pseudo-second-order model and the Langmuir isotherm model, respectively. At pH = 5, 318 K, the Langmuir maximum Pb(II) adsorption capacity of MnOx@Fe 3 O 4 @MCC was 446.43 mg/g, which is higher than many documented bio-based adsorbents. The results of Fourier transform infra-red and X-ray photoelectron spectroscopy indicated that the adsorption mechanisms for Pb(II) mainly involved surface complexation, ion exchange, electrostatic interaction and precipitation. Interestingly, the increased amount of carboxyl group on the surface of microcrystalline cellulose modified by KMnO 4 was one of the important reasons for the high Pb(II) adsorption performance of MnOx@Fe 3 O 4 @MCC. Furthermore, MnOx@Fe 3 O 4 @MCC exhibited excellent activity (70.6 %) after five consecutive regeneration cycles, indicating its high stability and reusability. Endorsing to the cost-effectiveness, environmentally friendliness, and reusable nature, MnOx@Fe 3 O 4 @MCC can be counted as a great alternative contender for the remediation of Pb(II) from industrial wastewater. [Display omitted] • MnO x @Fe 3 O 4 @MCC with abundant acid functional groups was synthesized. • MnO x @Fe 3 O 4 @MCC showed maximum adsorption capacity for Pb(II) of 446.43 mg·g−1 for Pb(II). • KMnO 4 activated the hydroxyl groups on Fe 3 O 4 @MCC surface to carboxyl groups. • Removal mechanism of Pb2+ by MnO x @Fe 3 O 4 @MCC was investigated and illustrated. [ABSTRACT FROM AUTHOR]

A macroporous polymeric resin, Amberlite XAD-1160, functionalized with −NO 2 (electron-acceptor) and −NH 2 (electron-donor) groups to prepare two new functional macroporous resins, NO 2 -XAD-1160 and NH 2 -XAD-1160 respectively, and three novel extractant-impregnated resins (EIRs) were prepared by impregnating XAD-1160, NO 2 -XAD-1160 and NH 2 -XAD-1160 with vesuvin, as an advantageous extractant. The sorption efficiencies of both VSV/NO 2 -XAD-1160 and VSV/NH 2 -XAD-1160 towards Pb(II) ion were compared with those of conventional VSV/XAD-1160 to gain insight about the effects of functional groups on the kinetics, equilibrium, thermodynamic and other sorption properties. Comparative studies showed that VSV/NO 2 -XAD-1160 benefits for using in full-scale treatment processes are more than those of VSV/XAD-1160 and VSV/NH 2 -XAD-1160. [ABSTRACT FROM AUTHOR]

In this work, we studied the natural bioaccumulation and biosorption of Pb(II) in several common edible macrofungi. The macrofungi include the following species: Lentinus edodes, Pleurotus eryngii, Flammulina velutipes, Hypsizygus marmoreus, and Agrocybe cylindracea. The present analysis of Pb(II) revealed distinct capabilities of metal accumulation among individual species. Moreover, the natural concentrations of lead did not reach a health risk level when cultivated in uncontaminated soil. In the biosorption experiment by edible macrofungi, we found that the equilibrium data of living sporocarp ( P. eryngii and H. marmoreus) and the homogenate of L. edodes and F. velutipes fit the Freundlich model well. Other data samples exhibited a better fit to the Langmuir model. The edible macrofungi showed a higher lead removal capacity than did other biosorbents. Furthermore, the pseudo-second-order kinetics model exhibited the best fit to the biosorption processes. The effectiveness of edible macrofungi as biosorbents for Pb(II) was confirmed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel DVP hybrid polymer was prepared for adsorption of Pb(II). • The maximum adsorption capacity of DVP for Pb(II) reached 349.5 mg g−1. • The Pb(II) removal performance was little affected by increased hardness cations. • The synergistic adsorption mechanism of thioether and carboxyl groups was proposed. It is a challenging task to remove Pb(II) ions efficiently from wastewater containing high concentrations of hardness ions. In this study, a novel hybrid polymer (DVP) for selective adsorption of Pb(II) ions was successfully prepared via photopolymerization of vinyl-POSS and dimercaptosuccinic acid (DMSA). The chemical structure and composition of DVP were characterized by FTIR, XPS, SEM, TEM, XRD and TGA techniques. DVP exhibited high efficiency in removing Pb(II) from aqueous solutions with a maximum adsorption capacity of 349.5 mg g−1 at pH 4, exceeding lots of adsorbents reported in the literature. The adsorption performance of Pb(II) by DVP was found to fit the Freundlich isotherm well and its kinetics followed the Elovich model. Moreover, DVP showed selective adsorption of Pb(II) in the presence of high concentrations of Ca(II) and Mg(II) ions and could reduce Pb(II) in real lake water to 25 ppb at a DVP dose of 1 g L−1. Moreover, the adsorption process of DVP was endothermic in nature. The adsorption mechanism demonstrated that Pb(II) ions can be chelated with the thioether and carboxyl groups of DVP simultaneously, which was confirmed by spectroscopic analysis and DFT calculations. Good reusability in continuous fixed-bed column experiments suggested that DVP was an ideal candidate for the selective removal of Pb(II) ions from contaminated aquatic systems. [ABSTRACT FROM AUTHOR]

The conventional adsorbent fabrication methods involve complicated processes and may cause secondary contaminations. Therefore, an effective eco-friendly method is required for the fabrication of heavy metal adsorbents using inexpensive and eco-friendly materials without secondary pollution during their process. In this study, nanofibrous membranes (NFMs) were fabricated via green electrospinning of poly(vinyl alcohol) (PVA), a hydrophilic polymer, and their water resistance was improved through simple heat treatment without using additional additives. Then, nanofibrous heavy metal adsorbents were prepared by dip-coating the NFMs in an aqueous solution of tannic acid (TA), a natural polyphenol. First, the adsorption/desorption behavior of TA on PVA NFMs during the TA coating process was investigated. In addition, the effects of TA coating on the mechanical properties and heavy metal adsorption characteristics of the PVA NFMs were analyzed. The TA coating significantly increased the mechanical strength, heat resistance, and heavy metal (Pb(II)) adsorption capacity of the PVA NFM. The Pb2+ adsorption amount of TA-coated PVA NFMs exhibited about 5–7 times higher than those of other heavy metal ions, indicating excellent selectivity for Pb2+. In addition, the TA-coated PVA NFMs retained >70% of its initial adsorption capacity even after four cycles of adsorption/desorption, indicating its reusability. [Display omitted] • PVA nanofibrous membrane (NFM) was prepared via green electrospinning. • Tannic acid (TA) coating improved the mechanical strength of PVA NFM by about 5 times. • TA-coated PVA NFM showed excellent adsorption capacity and selectivity for Pb2+. • TA-coated PVA NFM can be applied as a cost-effective and eco-friendly heavy metal adsorbent. [ABSTRACT FROM AUTHOR]

We have developed a crown ether based selective colorimetric sensing scheme for the determination of Pb(II) ion by using gold nanoparticles modified with dithiocarbamate derivative of 4′-aminobenzo-18-crown-6 that acts as a colorimetric probe. Monodisperse Au-NPs were prepared by reacting 4′-aminobenzo-18-crown-6 with carbon disulfide to generate the dithiocarbamate ligand which was then added to the Au-NPs to form a supramolecular assembly on their surface. The Au-NPs modified in this way undergo aggregation in the presence of Pb(II) ions, and this causes the color to change from red to blue. The Pb(II)-induced aggregation can be monitored by using UV-visible spectrometry and even with the bare eye. The absorbance ratio (A/A) is linearly related to the concentration of Pb(II) in the 0.1 to 75 μM range (with a correlation coefficient of 0.9957), and the detection limit is 50 nM which is lower than the allowable level (75 nM) as defined by the US EPA. The method was successfully applied to the determination of Pb(II) in spiked water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The crosslinked chitosan thin film had been studied as a sensor element of surface plasmon resonance (SPR) optical sensor. Crosslinked chitosan solution was synthesized by homogeneous reaction of medium molecular weight chitosan in aqueous acetic acid solution with glutaraldehyde as crosslinking agent. It was deposited on gold film by spin coating. Using SPR technique, the optical properties of crosslinked chitosan thin film before and after contacting with different concentration of Pb(II) ion in a range of 0.5–100ppm had been obtained by fitting. The resonance angle shifted to lower value as the Pb(II) ion concentration increased. Changes in the resonance angle (Δθ) are directly proportional to the concentration of Pb(II) ion solution. X-ray photoelectron spectroscopy (XPS) had been employed to confirm chemical elements and their bonding of the thin film prior to adsorption, as well as chemical interactions involved between Pb(II) ion and the thin film. [Copyright &y& Elsevier]

Abstract: SiO2/graphene composite was prepared through a simple two-step reaction, including the preparation of SiO2/graphene oxide and the reduction of graphene oxide (GO). The composite was characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray photoelectron spectroscopy, and what is more, the adsorption behavior of as-synthesized SiO2/graphene composite was investigated. It was interestingly found that the composite shows high efficiency and high selectivity toward Pb(II) ion. The maximum adsorption capacity of SiO2/graphene composite for Pb(II) ion was found to be 113.6mgg−1, which was much higher than that of bare SiO2 nanoparticles. The results indicated that SiO2/graphene composite with high adsorption efficiency and fast adsorption equilibrium can be used as a practical adsorbent for Pb(II) ion. [Copyright &y& Elsevier]

The ability of polystyrene-alumina-activated carbon composite as a synthetic adsorbent was investigated for the removal of Pb(II) ions from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, adsorbent dosage and contact time were studied. The optimum solution pH for the maximum adsorption of Pb(II) was found to be 4. Kinetic data were best described by pseudo-second-order model. The adsorption process followed both Langmuir and Freundlich adsorption isotherms at 30 °C. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic in nature. Desorption studies were carried out by batch and column operations and it was found that 97% Pb(II) could be recovered by the column process using 0.1 M HCl as eluent. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of polyaniline emaraldine salt (PAni-ES) by a chemical oxidative polymerization method. The obtained PAni-ES samples prepared under different conditions were used for the removal of indigo carmine anionic dye and Pb(II) ion from aqueous solutions. The results also showed that the pseudo-second-order kinetic model fitted better than the data obtained from pseudo-first-order model for the adsorption of anionic dye and Pb(II) ion onto PAni-ES. The fit of the data for indigo carmine and Pb(II) ion adsorption onto PAni-ES suggested that the Langmuir model gave closer fittings than Freundlich model. [ABSTRACT FROM AUTHOR]

Abstract: This manuscript reports sol–gel derived cross-linked poly(vinyl alcohol) (PVA)-3-(2-aminoethylamino) propyl trimethoxysilane (AEAPTMEOS) beads with low degree of swelling as a new adsorbent for the removal of Pb(II) from aqueous solution. Beads were prepared by condensation polymerization followed via acid-catalyzed sol–gel process in presence of non-ionic surfactant. Cross-linking was achieved by glutaraldehyde. Presence of –NH/–NH2 groups in beads provide active sites for Pb(II) adsorption, and were responsible for high adsorption capacity. SEM/TEM studies confirmed the spherical and rough surface morphology, which was changed after Pb(II) adsorption. For the removal of Pb(II) in aqueous solution, effect of equilibrium time, temperature, pH, adsorbent dose and adsorbate concentration were investigated in batch process. Pseudo-first- and pseudo-second-order kinetics were also evaluated. The equilibrium adsorption followed Langmuir and Freundlich isotherms. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° revealed endothermic and spontaneous adsorption. Monolayer adsorption capacity (Q 0) value for the developed PVA-AEAPTMEOS beads was 67.56mgg−1 at pH: 5.0, much higher as compared to other adsorbents reported in literature. Desorption studies also suggested that cross-linked PVA-AEAPTMEOS beads can be effectively utilized for the removal of Pb(II) from wastewater. [Copyright &y& Elsevier]

• A Mg(OH) 2 /talc nanocomposite was prepared by hydrothermal method. • The occurrence state of magnesium had great influence on the adsorption of Pb(II). • Adsorption mechanism was Electrostatic attraction and ion exchange. • Adsorption occurred on non-uniform surface with multilayer. [Display omitted] It is of great significance in the resource utilization to make full use of the magnesium in the low-grade mineral to prepare new adsorption materials. In this paper, a Mg(OH) 2 /talc nanocomposite was prepared by migrating part of Mg2+ from the talc internal structure to the outer surface through a facile acid leaching, coprecipitation and hydrothermal method. The maximum adsorption capacity of Mg(OH) 2 /talc was 483.33 mg/g, which was significantly improved compared with that of Acid-activated Talc (4.79 mg/g) and pristine talc (259.17 mg/g). The main adsorption mechanism of Mg(OH) 2 /talc for Pb(II) ions involved electrostatic attraction and ion exchange. Adsorption and desorption cycle experiment showed that, although Mg(OH) 2 /talc provides a large adsorption capacity for the first time, but the second adsorption capacity decreased by 42%, the third to the fifth kept stable adsorption capacity. This results indicated that the surface of magnesium hydroxide was not stable, only used it once. While magnesium hydroxyl in talc was stable, it could provide stable cycle performance. This work can provide reference for efficient utilization of clay minerals and design novel cost-efficient adsorbents. [ABSTRACT FROM AUTHOR]

Treating the effluents from industries by using biological and agricultural wastes is an emerging field of research. In this study, three different biosorbents are prepared from tamarind seeds such as; raw, sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seed powder has been utilized to expel the Pb (II) ions from synthetic solution. The surface characteristics of the newly synthesized raw and surface modified agro-waste biomass were studied by FTIR and SEM. An experimental study was carried out to investigate the effect of different parameters on adsorption of Pb(II) ions using raw, sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seeds. The maximum Pb(II) ions adsorption was found at pH - 6.0, temperature - 303 K, biosorbent dosage - 3.5 g/L and contact time - 60 min for raw tamarind seeds and 30 min for sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seeds. The adsorption mechanism was described by Langmuir isotherm and pseudo-first order kinetic model. Among the three biosorbents, ultrasonic-assisted surface-modified tamarind seeds show higher adsorption capacity (18.86 mg/g) of Pb(II) ions removal from the synthetic solution. The thermodynamic study declared that the present Pb(II) ions adsorption onto the prepared biosorbents was spontaneous, exothermic and followed physical adsorption process. Results have shown that tamarind seed was found to be the best adsorbent in the expulsion of Pb(II) ions from the wastewater environment. • Tamarind seeds was utilized as low-cost biosorbent for Pb(II) ions adsorption. • Ultrasonic waves are adopted to improve the surface properties of agro-waste. • The maximum adsorption capacity of UATS was found to be 18.86 mg/g. • Langmuir and pseudo-first order models showed good fit to the Pb(II) ion adsorption. • Biosorption of Pb(II) ions onto RTS, SMTS and UATS are follows physisorption mechanism. [ABSTRACT FROM AUTHOR]

Cassia fistula seeds has been utilized for the abstraction of Pb(II) ions from the aqueous environment. Raw Cassia fistula seeds (RCF) and three different surface modified (physically treated – PMCF and chemically treated – HMCF and SMCF) adsorbent material were taken for investigation. The adsorption properties of these materials and their contact amongst the Pb(II) ion and sorbent materials were characterized by FTIR and SEM analysis. The parameters influencing the adsorption capacity of varied adsorbents were evaluated: maximum solution pH for Pb(II) is 5.0; interactive time is 30 min; dosage is 8.0 g/L for RCF, 4.0 g/L for HMCF, 2.5 g/L for PMCF and 1.0 g/L for SMCF. The modelling study reveals that Freundlich isotherm and Pseudo first order kinetics fits well and the utmost adsorption measurements for the varied adsorbents were found to be 13.22, 28.28, 48.66 and 129.3 mg/g, respectively. [Display omitted] • The performance of RCF, HMCF, PMCF and SMCF for Pb(II) ion was elucidated. • Potential of adsorbents were characterized for Pb(II) ions removal. • The isotherm calculations indicated that Freundlich model was best obeyed. • Thermodynamic investigations confirmed the exothermic nature. [ABSTRACT FROM AUTHOR]

The method of solvothermal by one-step operation has been performed to synthesize of magnetic amine-functionalized sugarcane bagasse biocomposites (SB-MH). The obtained SB-MH contains 62.34% of Fe, 17.8 mmol/g of amine, and a magnetic property of 19.46 emu/g. The biocomposite surface area increased significantly from 1.617 to 25.789 m2/g after amine functionalization. The optimum condition of SB-MH used for Pb(II) ion removal was achieved at pH 5 for 360 min with adsorption capacity of 203.522 mg/g. The pseudo 2nd order was well-fitted to the model of Pb(II) ion adsorption. Meanwhile, other contaminant parameters number of Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), and dye in wastewater were also remarkably reduced by about 74.4%, 88.0%, and 96.7%, respectively. The reusability of SB-MH with 4th repetitions showed only a slight decrease in performance of 5%. Therefore, the proposed magnetic amine-functionalized sugarcane bagasse biocomposites lead to a very potential adsorbent implemented in high scale due to high surface area, easy separation, stable materials and capability to adsorb contaminants from aqueous solution. [ABSTRACT FROM AUTHOR]

Adsorption of Pb(II) ions in aqueous systems by newly developed mixed biomass has been explored. Mixed biomass was prepared from agro-waste (raw Banyan tree bark, RBTB) and bacterial biomass (Pannonibacter phragmitetus). Chemical modification by sulphuric acid treatment of raw banyan tree bark (SMBTB) was accomplished for the effective separation of toxic Pb(II) ions from the aquatic system. FTIR, SEM and EDX analysis was utilized to deduce sorption characteristics of mixed biomass. Pb(II) ions maximal removal has occurred at pH-6.0, lead (II) ions concentration-25 mg/L, time and mixed biomass dosage (60 min and 3.5 g/L for RBTB – Pannonibacter phragmitetus ; 30 min and 1.5 g/L for SMBTB – Pannonibacter phragmitetus) and temperature (30 °C). Data from equilibrium isotherm and kinetic analysis was best suited to the Langmuir model and pseudo-first-order kinetics. The spontaneous and exothermic nature of Pb(II) ions removal was described by thermodynamic parameters. The mixed biomass proved to be an effective and potential mixed biosorbent for toxic lead removal from solutions. • Agro waste biomass showed that low cost and effective adsorbent. • Sulphuric acid modification enhances the adsorption capacity. • Langmuir isotherm and Pseudo-first-order kinetics showed better fit. • Adsorption of Pb(II) ion was spontaneous and thermodynamically exothermic. [ABSTRACT FROM AUTHOR]

New selective carbonaceous sorbent is one-pot fabricated using microburst of bi-metal salts in order to eliminate carcinogens in environment. We used discarded cigarette butts as carbon source, aluminum nitrate and ferrous acetate as pore-forming agents to prepare the versatile sorbent with a developed porosity and the well-exposed metal oxides in order to replace zeolites for the selective adsorption in environment protection. Numerous finely divided porous particles endowed the composite a surface area of over 350 m2g-1, enabling it to be the best sorbent of tobacco specific nitrosamines (TSNA) to date in solution. It adsorbed 41% of TSNA among hundreds of components in tobacco extract solution or 142 mg g−1of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) in aqueous solution, and rapidly trapped Pb(Ⅱ) at the S/L of 0.2 within 10 min with a capacity of 153 mg g−1. Moreover, new sorbent could catalyze the degradation of NNK in mild conditions, which is rare but is very important for environmental protection. [Display omitted] • One-pot fabricating selective sorbent from discarded cigarette butts eco-friendly. • New environmental selective sorbent traps TSNA better than zeolite. • The versatile sorbent catalyzes the degradation of NNK in mild condition. • It is the fastest trapper of lead ion in aqueous solution to date. • Cleaning environment with recycle of waste. [ABSTRACT FROM AUTHOR]

A method is described for simultaneous voltammetric determination of the pesticides triazophos (TRS) and thiacloprid (THD). A glassy carbon electrode (GCE) was modified with a metal-organic framework (type UiO-66-NH2) which has a large specific surface (1018 m2·g−1) and contains large amounts of Cd(II) and Pb(II) ions, with adsorption capacities of 230 and 271 mg·g−1, respectively. The antigen-loaded particles were then bound to antibody, magnetically separated, and analyzed by square wave voltammetry to give signals for Cd(II) and Pb(II) at −0.82 and − 0.56 V (vs. Ag/AgCl) for TRS and THD, respectively. Under optimized conditions, the method has a wide linear range (0.2-750 ng·mL−1) and low detection limits (0.07 and 0.1 ng·mL−1 at a S/N of 3 for TRS and THD, respectively). It is perceived that this assay represents a useful tool for simultaneous determination of multiple pesticide residues. The method has a wide scope in that may be extended to monitoring of other small organic pollutants by changing the types of metal ions and by using other antibodies.Schematic presentation of an amino-modified metal-organic framework (type UiO-66-NH2) loaded with Cd(II) and Pb(II) ions for simultaneous electrochemical immunosensing of triazophos (TRS) and thiacloprid (THD). It is based on the fabrication of antigen (Ab)-immobilized UiO-66-NH2-based signal tags (a), and of an antibody (Ab)-immobilized magnetic bead (MB-COOH)-based capture probes (b). [ABSTRACT FROM AUTHOR]