Arsenic Ions Research Articles

Highly Selective Capacitive Adsorption and Rapid Desorption of Arsenic Ions in Wastewater Achieving by a Recyclable Urchin-Like Iron-Manganese Composite Electrode

Highly Selective Capacitive Adsorption and Rapid Desorption of Arsenic Ions in Wastewater Achieving by a Recyclable Urchin-Like Iron-Manganese Composite Electrode

Biochemical, molecular and in silico characterization of arsenate reductase from Bacillus thuringiensis KPWP1 tolerant to salt, arsenic and a wide range of pH.

The present study characterized aresenate reductase of Bacillus thuringiensis KPWP1, tolerant to salt, arsenate and a wide range of pH during growth. Interestingly, it was found that arsC, arsB and arsR genes involved in arsenate tolerance are distributed in the genome of strain KPWP1. The inducible arsC gene was cloned, expressed and the purified ArsC protein showed profound enzyme activity with the KM and Kcat values as 25µM and 0.00119s-1, respectively. In silico studies revealed that in spite of 19-26% differences in gene sequences, the ArsC proteins of Bacillus thuringiensis, Bacillus subtilis and Bacillus cereus are structurally conserved and ArsC structure of strain KPWP1 is close to nature. Docking and analysis of the binding site showed that arsenate ion interacts with three cysteine residues of ArsC and predicts that the ArsC from B. thuringiensis KPWP1 reduces arsenate by using the triple Cys redox relay mechanism.

Армбрустерит как перспективный материал для современного материаловедения

The description of a new and insufficiently studied mineral armbrusterite is presented in this paper. The mineral was analyzed from the point of view of its chemical properties and prospects for practical application. The mineral's sorption properties for arsenic and cesium ions were studied. The possibility of synthesis an analog of the mineral due to hydrothermal synthesis was estimated

Sorptive removal of aqueous arsenite and arsenate ions onto a low cost, calcium modified Moringa oleifera wood biochar (CaMBC)

Arsenicosis, due to consumption of an elevated amount of arsenic-containing groundwater is a serious issue related to human health. The ubiquitous nature of arsenic is also a part of agricultural soil solution and its uptake by edible plants imposes a considerable human health risk. A calcium pretreated wood of Moringa oleifera was pyrolyzed and converted into biochar. The resultant biochar was examined for arsenite and arsenate uptake from an aqueous solution. Further, characterization of biochar was performed using Fourier transformed infrared spectroscopy (FT-IR) and Scanning electron microscope with energy dispersive x-ray (SEM-EDAX) analysis. Results suggested the involvement of different functional groups of calcium-modified biochar in As(III) and As(V) sorption processes. Experimental data of batch sorption revealed that CaMBC could adsorb analyte ions from pH 5.0 to 7.0 with maximum percentage removal, that is, 87.27 and 94.52% at adsorbent concentration 2 g/L. A high loading capacity of prepared adsorbent was found to be 37.22 mg/g for arsenate and 33.44 mg/g for arsenite ions. The sorption occurred due to chemical interaction between functional group and arsenic ions, which existed over the surface of prepared biochar. The spontaneous sorption makes a CaMBC, an ideal candidate for the removal of dissolved arsenite, arsenate ions.

Continuous electrodeionization on the removal of toxic pollutant from aqueous solution

Arsenic is among the most harmful pollutants and can create severe public health effects from such a small volume of water. Electrodeionization was used to eradicate arsenic ions from groundwater in this research. Electrodeionization system incorporates hybrid electro dialysis/ion exchange to remove and concentrate Arsenic ions from water, then reuses the processed water. The findings indicate that Electrodeionization will remove arsenic from liquids at intensities varies from 5 to 25 ppm in batch recirculation mode and 5–15 ppm in continuous column analysis. Although the device demonstrated the maximum ion percentage removal, of about 100 percent, when operated at a low voltage range from 5 to 20 V. A number of column studies were conducted to establish the breakthrough curves with concentrations ranging from 5 to 15 ppm, applied voltages ranging from 5 to 20 V, and flow rates ranging from 5 to 20 mL/min. For the present work, Arsenic was eliminated up to 98.8 percent in the trials reported here, with energy usage in the Electrodeionization unit varying around 3.88 and 60.7 kW h per kilogram of removed arsenic. This demonstrates the application's ability and productivity in removing Arsenic from aqueous solutions.

Examples in the detection of heavy metal ions based on surface-enhanced Raman scattering spectroscopy

Abstract Heavy metals have been widely applied in industry, agriculture, and other fields because of their outstanding physics and chemistry properties. However, heavy metal pollution is inevitable in the process of mass production and emission. Heavy metal ions will cause irreversible harm to the human body and other organisms due to their nondegradable nature even at low concentrations of exposure and ingestion. Therefore, it is of great significance for human health and ecological environment to develop high accuracy and sensitivity as well as stable techniques for detecting heavy metal ions. In recent years, surface-enhanced Raman scattering (SERS) spectroscopy has been regarded as a promising new technique for the determination of trace heavy metal ions on account of its special fingerprint identification capability, high sensitivity, rapid detection ability, and simple operation. This review summarized in detail the basic principles and strategies for detecting mercury ions, copper ions, arsenic ions, zinc ions, cadmium ions, lead ions, and chromium (VI) ions as well as the current challenges and future trends for the determination of heavy metal ions based on SERS technology.

A flexible Eu:Y2O3-polyvinyl alcohol photoluminescent film for sensitive and rapid detection of arsenic ions

The present article reports the synthesis and characterization of Eu:Y2O3 nanophosphor (EYN) and EYN dispersed polyvinyl alcohol (PVA) fluorescent film (EYF), with subsequent studies of sensing behavior for the detection of heavy metal ions particularly arsenic ions (As3+) in real water samples. Various characterization techniques have been employed to confirm the successful phase formation/stability of EYF. The maximum emission peak for EYF with excitation wavelength 394 nm has been obtained as 612 nm and hence picked for the demonstration of PL (Photoluminescence) response with arsenic ions solution in natural pH range (at ∼ 7 pH). Fluorescence intensities of EYF have been found to decrease quickly with As3+ ion contents due to the reduction in the population of Eu3+ ions in the 5D0 level and also due to formation of direct or indirect coordinate bonds with Eu3+. The PL intensity of the EYF nanoprobe has completely been quenched at 260 µg/L concentration of As3+ ions with the limit of detection 57.5 ng/L (=0.057 ppb) for 0–100 µg/L linear range. The selectivity of EYF probe is also investigated for various common cations and ions present in real water samples. Moreover, sensing probe has been examined with different river water samples and shows recovery percent in between 98 and 105 & maximum % RSD value as 5.76 with n = 5 tests. Furthermore, the EYF sensing probe shows a visible color change with the contaminated water under UV–Vis light which useful for the onsite detection of arsenic concentration. Hence, EYF endows a promising pathway for a flexible, portable, low-cost sensing device for the sensitive and selective detection of arsenic ions in real water samples.

One-step removal of high-concentration arsenic from wastewater to form Johnbaumite using arsenic-bearing gypsum

High-level arsenic-containing wastewater (HAW) causes serious environmental pollution. Chemical precipitation is the most widely used technology for treating HAW. However, chemical precipitation generates huge amounts of hazardous solid wastes, which leads to secondary pollution. In this work, an efficient method, producing no secondary pollution was developed for one-step complete removal of As(V) from HAW using a hazardous solid waste namely arsenic-bearing gypsum (ABG). After the treatment, ABG was transformed into highly stable and environment-friendly mineral Johnbaumite. Meanwhile, the arsenic concentration in the wastewater decreased from 10,000 mg L−1 to 0.22 mg L−1 under optimized hydrothermal conditions (ABG dosage of 50 g L−1, solution pH of 13.5, temperature of 150 °C for 12 h). The mechanism mainly included the following processes: (i) The phase transformation of ABG resulted in the release of calcium and hydrogen arsenate ions in ABG, (ii) Hydrogen arsenate ions transformed into arsenate ions in alkaline environment, and (iii) Under alkaline conditions, calcium ions combined with arsenate ions to form Johnbaumite, whereas the hydrothermal conditions accelerated the crystal growth of Johnbaumite. This study provides a new idea for the synchronous treatment of toxic heavy metal-containing wastewaters and hazardous solid wastes.

Nanomaterials as adsorbents for As(III) and As(V) removal from water: A review

Freshwater demand will rise in the next couple of decades, with an increase in worldwide population growth and industrial development. The development activities, on one side, have increased the freshwater demand. However, the ground water has been degraded. Among the various organic and inorganic contaminants, arsenic is one of the most toxic elements. Arsenic contamination in ground waters is a major issue worldwide, especially in South and Southeast Asia. Various methods have been applied to provide a remedy to arsenic contamination, including adsorption, ion exchange, oxidation, coagulation-precipitation and filtration, and membrane filtration. Out of these methods, adsorption of As(III)/As(V) using nanomaterials and biopolymers has been used on a wide scale. The present review focuses on recently used nanomaterials and biopolymer composites for As(III)/As(V) sorptive removal. As(III)/As(V) adsorption mechanisms have been explored for various sorbents. The impacts of environmental factors such as pH and co-existing ions on As(III)/As(V) removal, have been discussed. Comparison of various nanosorbents and biopolymer composites for As(III)/As(V) adsorption and regeneration of exhausted materials has been included. Overall, this review will be useful to understand the sorption mechanisms involved in As(III)/As(V) removal by nanomaterials and biopolymer composites and their comparative sorption performances.

A novel and indirect method for L-cysteine detection in traditional Chinese medicines by chemical vapor generation-atomic fluorescence spectrometry

L-Cysteine (L-Cys) is one of the material bases for the sweet taste of traditional Chinese medicines (TCMs), as well as the material basis for the pharmacological activity of TCMs in the treatment of diseases. Therefore, the rapid and accurate determination of the concentration of L-Cys has a certain significance for the quality evaluation of TCMs. In this work, a simple method was developed for label-free and indirect detection of L-Cys by chemical vapor generation-atomic fluorescence spectrometry (CVG-AFS) based on the phenomenon that L-Cys can inhibit the CVG of arsenic ion (As(III)). Therefore, the AFS signal is inversely proportional to the concentration of L-Cys. The effects of the concentration of hydrochloric acid (HCl) and potassium borohydride (KBH4) in the CVG process and the reaction time between L-Cys and As(III) have been investigated. Under the optimal experimental conditions, it shows a good linearity in the concentration range of 2–18 mM. The limit of detection (LOD) of the presented method is 2.8 μM, with a relative standard deviation (RSD) of 0.5%. The method has been successfully applied in the analysis of L-Cys in several animal TCMs with good recoveries.

Nanocarbon hybrid for simultaneous removal of arsenic, iron and manganese ions from aqueous solutions

Heavy metal contamination is a severe problem with serious ecological and human health effects due to its toxic effect and tendency to accumulate throughout the food chain. Batch experiments were conducted to investigate the simultaneous removal of arsenic, iron and manganese ions from aqueous solutions using Nanocarbon hybrid (NCH). Nanocarbon hybrid (NCH) of carbon xerogel decorated with 1wt% multi-walled carbon nanotubes was prepared by carbonization at 850 °C for 2 h. The TEM, SEM, EDX, FTIR, and N2 adsorption-desorption measurements were used to characterize the prepared NCH. NCH is enriched with surface oxygen functional groups and micropores as well as it have total surface area of 162 m2/g and total pore volume of 0.129 cm3/g. The adsorption of metal ions onto NCH, which confirmed by EDX, happened quickly, with 30%, 97%, and 41% of As, Fe, and Mn adsorbed in less than 10 min, however the equilibrium time was achieved in less than 30 min. The maximum adsorption capacities for As, Fe, and Mn ions onto NCH were 20, 48, and 21 mg/g, respectively. The experimental adsorption results of the three metal ions showed linearly fitting with Freundlich isotherms. In addition, the computed adsorption energies for Fe, Mn, and As ions were 4.08, 1.95, and 2.42 kJ/mol, indicating physical adsorption. NCH are easily regenerated and reusable sorbent owing to the adsorption–desorption studies. Conclusively, NCH is promising material for removing mixture of metal ions from aqueous media.

Biocompatible Silver Nanoparticles: Study of the Chemical and Molecular Structure, and the Ability to Interact with Cadmium and Arsenic in Water and Biological Properties.

In the field of research for designing and preparing innovative nanostructured systems, these systems are able to reveal the presence of heavy metals in water samples, and can efficiently and selectively interact with them, allowing for future applications in the field of water remediation. We investigated the electronic and molecular structure, as well as the morphology, of silver nanoparticles stabilized by mixed biocompatible ligands (the amino acid L-cysteine and the organic molecule citrate) in the presence of cadmium and arsenic ions. The molecular, electronic, and local structure at the ligands/silver nanoparticles interface was probed by the complementary synchrotron radiation-induced techniques (SR-XPS, NEXAFS and XAS). The optical absorption (in the UV-Vis range) of the nanosystem was investigated in the presence of Cd(II) and As(III) and the observed behavior suggested a selective interaction with cadmium. In addition, the toxicological profile of the innovative nanosystem was assessed in vitro using a human epithelial cell line HEK293T. We analyzed the viability of the cells treated with silver nanoparticles, as well as the activation of antioxidant response.

Simultaneous Biosorption of Arsenic and Cadmium onto Chemically Modified Chlorella vulgaris and Spirulinaplatensis

The biosorption behaviour of arsenic(V) and cadmium(II) ions by unmodified and five types of chemically modified Chlorella vulgaris and Spirulina platensis was investigated. The biosorption rates of As(V) and Cd(II) in binary metal solutions were lower than those in sole metal systems, which exhibited a competition between As(V) and Cd(II) ions to occupy the active sites of the adsorbent. Among the five chemical reagents, NaCl and ZnCl2 were the most suitable modifiers for improving the biosorption performance of C. vulgaris and S. platensis, respectively. The maximum biosorption capacities of As(V) and Cd(II) were: (a) 20.9 and 1.2 mg/g, respectively, for C. vulgaris modified with NaCl; (b) 24.8 and 29.4 mg/g, respectively, for S. platensis modified with ZnCl2, which were much higher than those using other chemically modifying methods. The pseudo-second-order kinetic model fitted well with all the biosorption processes. The SEM analysis revealed that the modification changed the surface morphologies and enhanced the porosity of the algae biomass. The FTIR analysis established the presence of diverse groups of compounds that were largely hydroxyl, carboxylate, amino, and amide groups on the adsorbents that contributed significantly to the upregulated biosorption. This work showed the potential application of chemically modified C. vulgaris and S. platensis biomasses to effectively remove both from water.

Immobilization and redistribution process of As(V) during As(V)-bearing ferrihydrite reduction by Geobacter sulfurreducens under the influence of TiO2 nanoparticles

The redistribution process of arsenate (As(V)) and the variation in As(V) content in different locations must be clarified to ensure low mobility of As(V) during microbial ferrihydrite reduction. In this study, we investigated As(V) immobilization and redistribution processes when ferrihydrite was incubated with Geobacter sulfurreducens in the presence of titanium dioxide (TiO2) nanoparticles. Our study results showed that, As(V) in the aqueous phase and ferrihydrite were redistributed on light minerals (goethite), heavy minerals (ferrihydrite and magnetite), and extracellular polymeric substances (EPS) induced by G. sulfurreducens during ferrihydrite reduction. Interestingly, we found that As(V) in the form of arsenate ion (AsO43-) was adsorbed by the functional groups of the EPS, while the formed FeII3(AsVO4)2 was wrapped in the network structure of EPS. Moreover, the addition of TiO2 nanoparticles did not promote but delayed the entire ferrihydrite reduction, As(V) immobilization and redistribution processes. Furthermore, changes in the aqueous arsenic and iron concentrations are closely related to the formation time of secondary minerals. Our study findings provide new insights into the As(V) immobilization process mediated by G. sulfurreducens under anaerobic conditions.

Novel monomers with N‐methyl‐D‐glucamine segments and their application in structured porous materials for arsenic capture

AbstractThe N‐methyl‐D‐glucamine moieties exhibit high ability and selectivity toward arsenate ions in water by a complexation mechanism that involves their hydroxyl groups. In this work, the syntheses of two monomers containing N‐methyl‐D‐glucamine, namely 4‐vinylbenzyl‐N‐methyl‐D‐glucamine (VbNMDG), and N‐methyl‐D‐glucamine methacrylamide (MNMDG) were studied. Different synthetic routes were considered in order to obtain liquid monomers able to polymerize and selectively capture arsenic. Furthermore, the incorporation of protective groups like trimethylsilyl moieties in the molecular structure was assessed to prevent transfer reactions during further polymerization. After polymerization, hydroxyl groups were deprotected using hydrofluoric acid. Following this methodology, structured microporous polymeric films based on colloidal crystal templates were prepared. NMR and FTIR techniques were used to follow the reactions and to determine the chemical structure of the obtained products. The morphology of materials was characterized by SEM. The performances of the developed polymeric films to selectively capture arsenic were determined. Films showed an improved and reproducible sensitivity to arsenic detection exhibiting high values of arsenic capturing capability (around 90%).

Optimization of arsenic ions adsorption and removal from hospitals wastewater by nano-bentonite using central composite design

Nano-bentonite was prepared from Iraqi bentonite clay by the co-precipitation method and the adsorption technique was used under many factors to determine the adsorption capacity (q) and removal% of arsenic ions (As) from the hospital's wastewater. The optimization process was conducted to choose the optimal parameters for adsorption and removal of arsenic by applying the central composite design (CCD) to form a surface response with three levels and three central points. Three operational factors were optimized of pH (5.5), bentonite dose (100 mg/L), and contact time (5 min), as well as developing the regression quadratic equations to assess the important models for the arsenate adsorbing and removing which dependent on the correlation factor (R2) that was (q = 0.9998) and (removal% = 0.9709), the adsorption isotherm results were fit well with the Langmuir model (R2 = 0.972), and the adsorption kinetics results were perfect with the second model (R2 = 0.951). We conclude that bentonite clay is a good adsorbent that can be used in the processes of removing toxic ions from water.

Design and Prototyping of Genetically Encoded Arsenic Biosensors Based on Transcriptional Regulator AfArsR

Genetically encoded biosensors based on engineered fluorescent proteins (FPs) are essential tools for monitoring the dynamics of specific ions and molecules in biological systems. Arsenic ion in the +3 oxidation state (As3+) is highly toxic to cells due to its ability to bind to protein thiol groups, leading to inhibition of protein function, disruption of protein–protein interactions, and eventually to cell death. A genetically encoded biosensor for the detection of As3+ could potentially facilitate the investigation of such toxicity both in vitro and in vivo. Here, we designed and developed two prototype genetically encoded arsenic biosensors (GEARs), based on a bacterial As3+ responsive transcriptional factor AfArsR from Acidithiobacillus ferrooxidans. We constructed FRET-based GEAR biosensors by insertion of AfArsR between FP acceptor/donor FRET pairs. We further designed and engineered single FP-based GEAR biosensors by insertion of AfArsR into GFP. These constructs represent prototypes for a new family of biosensors based on the ArsR transcriptional factor scaffold. Further improvements of the GEAR biosensor family could lead to variants with suitable performance for detection of As3+ in various biological and environmental systems.

Probe decorated porous silica and polymer monoliths as solid-state optical sensors and preconcentrators for the selective and fast recognition of ultra-trace arsenic ions

In this work, we manifested a new approach in designing solid-state colorimetric sensors for the selective optical sensing of As3+. The sensor fabrication is modulated using, (i) a cubic mesopores of ordered silica monolith, and (ii) a bimodal macro-/meso-porous polymer monolith, as hosting templates that are immobilized with a tailor-made chromoionophoric probe (DFBEP). The surface morphology and structural dimensions of the monolith templates and the sensor materials are characterized using p-XRD, XPS, FE-SEM-EDAX, HR-TEM-SAED, FT-IR, TGA, and BET/BJH analysis. The sensing components such as pH, probe content, sensor dosage, kinetics, temperature, analyte concentration, linear response range, selectivity, and sensitivity are optimized to arrive at the best sensing conditions. The silica and polymer-based monolithic sensors show a linear spectral response in the concentration range of 2–300 and 2–200 ppb, with a detection limit of 0.87 and 0.75 ppb for As3+, respectively. The real-time ion-monitoring propensity of the sensors is tested with spiked synthetic and real water samples, with a recovery efficiency of ≥99.1% (RSD ≤1.57%). The sensors act as both naked-eye optical sensors and preconcentrators, with a response time of ≤2.5 min. The molecular and photophysical properties of the DFBEP-As3+ complex are studied by TD-DFT calculations, using the B3LYP/6–31G (d,p) method.

Determination of Chromium(VI), Chromium(III), Arsenic(V), Aluminum(III), Iron(II), and Manganese(II) by Colorimetry and Surface-Enhanced Raman Scattering (SERS) Using Ferulic Acid Functionalized Silver Nanoparticles

Plasmonic nanoparticles having localized surface plasmon resonance in the visible and infrared region are potential candidates for the fabrication of simple, rapid, selective and specific metal ion detection systems based on colorimetry and surface-enhanced Raman spectroscopy. The study describes simple approaches for selective colorimetric and surface-enhanced Raman scattering determination of aluminum(III), chromium (VI), chromiun(III), manganese (II), iron(II) and arsenic (V) ions in aqueous medium using ferulic acid functionalized silver nanoparticles (F-AgNPs) synthesized by chemical reduction and microwave assisted method. The analysis of photographs reveals that ferulic acid functionalized silver nanoparticles synthesized by chemical reduction (C-F-AgNPs) sensitively detect Al(III) ions in aqueous media while nanoparticles synthesized by microwave reduction method can be used to determine As(V), Mn(II) and Fe(II) ions. In addition, C-F-AgNPs also enhance the Raman spectral profile of the water samples spiked by Cr(III) ions giving a peculiar vibration spectral feature that assists in the detection of Cr(III) ion in aqueous medium. Moreover, ferulic acid functionalized silver nanoparticles synthesized by the microwave assisted method (M-F-AgNPs) increase the intensity of Raman bands in the spectral profile of the water samples spiked with Cr(VI) and Mn(II) ions. The specific and selective interactions of F-AgNPs with the Cr(VI), Cr(III), Mn(II), Fe(II), Al(III) and As(V) leading to the aggregation of the dispersed silver nanoparticles enable their determination in aqueous media . The results of the present study shows the potential of F-AgNPs based sensor probes toward conceptualizing and fabricating simple, rapid and cost effective detection tools onsite determination of metal ions in aqueous media.

Surface protection method for the magnetic core using covalent organic framework shells and its application in As(III) depth removal from acid wastewater

Fe3O4-based materials are widely used for magnetic separation from wastewater. However, they often suffer from Fe-leaching behavior under acidic conditions, decreasing their activity and limiting sustainable practical applications. In this study, covalent organic frameworks (COFs) were used as the shell to protect the Fe3O4 core, and the Fe3O4@COF core-shell composites were synthesized for As(III) removal from acid wastewater. The imine-linked COFs can in situ grow on the surface of the Fe3O4 core layer by layer with [COFs/Fe3O4]mol ratio of up to 2:1. The Fe-leaching behavior was weakened over a wide pH range of 1-13. Moreover, such composites keep their magnetic characteristic, making them favorable for nanomaterial separation. As(III) batch adsorption experiments results indicated that, when COFs are used as the shell for the Fe3O4 core, a balance between As(III) removal efficiencies and the thickness of the COF shell exists. Higher As(III) removal efficiencies are obtained when the [COFs/Fe3O4]mol ratios were < 1.5:1, but thicker COF shells were not beneficial for As(III) removal. Such composites also exhibited better As(III) removal performances in the pH range of 1–7. Over a wide pH range, the zeta potential of Fe3O4@COF core-shell composites becomes more positive, which benefits the capture of negative arsenic ions. In addition, thinner surface COFs were favorable for mass transfer and facilitating the reaction of Fe and As elements. Our study highlights the promise of using COFs in nanomaterial surface protection and achieving As(III) depth removal under acidic conditions.