Arsenite Ions Research Articles

Chromogenic detection of fluoride, dihydrogen phosphate, and arsenite anions based on 2,4-dinitrophenyl hydrazine receptors: spectral and electrochemical study

ABSTRACT The colorimetric recognition of biologically relevant fluoride (F−), acetate (AcO−), and dihydrogen phosphate (H2PO4 −) ions, and poisonous arsenite (AsO2 −) ions, was devised and new receptors for these anions synthesised via the Schiff base condensation procedure. UV–visible titration, fluorescence titration, 1H-NMR titration, and cyclic voltammetry were used to explore the interactions of receptors R1–R3 with anions and possible detection mechanisms. The synthesised probes could sense inorganic fluoride, acetate, dihydrogen phosphate, and arsenite in the organo–aqueous medium (H2O/ Dimethylsulphoxide, 1: 9, v/v) and displayed a change in colour detectable to the naked eye. Out of the three synthesised receptors, receptor R1 showed better sensing ability of fluoride, acetate, dihydrogen phosphate, and arsenite ions in the organo–aqueous medium with a lower detection limit of 0.1 ppm, 0.171 ppm, 0.194 ppm, and 0.144 ppm, respectively. All three receptors formed complexes with the anions through H-bonding interaction followed by deprotonation of the NH proton.

Comparative study on biosorption of arsenite ions onto raw and chemically activated orange peel powder in batch reactor

In present work, comparative study of sorption potential of raw and chemically activated orange peel powder has been explored for the removal of arsenite ions (As III) from wastewater. Several operating parameters such as contact time, adsorbent dose, adsorbate ion concentration, solution pH as well as temperature were studied in batch reactor. Surface as well as physicochemical analysis of orange peel was done by using FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), proximate and ultimate analysis. Maximum removal of As (III) 86.3% and 87% was obtained at initial metal ion concentration 20 mg/l and 25 mg/L, optimum pH 2 and 2.8, temperature 30°C and 25°C, contact time 120 and 150 minutes as well as the adsorbent dose 4g for raw and chemically activated orange peel respectively. Modeling of experimental data showed that Freundlich model (R2 = 97.45) had a better fit over Langmuir isotherm (R2 = 96.33) for raw orange peel and the Freundlich model (R2 =99.8%) in comparison to Langmuir model (R2 =94.5%) shows better fit. The present comparative study depicts that the chemically activated orange peel powder are more effective than raw orange peel powder. Thus, orange peel is found to be promising simple material for removal of arsenite ions (As III) ions.

Development of a potentiometric sensor for dihydrogen arsenite ion determinationin environmental samples employing a simplex lattice mixture design

ABSTRACT Arsenic is a widely utilised element in various industries that this element and its species have high toxicity even at very low concentrations. We introduced a potentiometric sensor using a carbon paste electrode (CPE) as an indicator electrode for the dihydrogen arsenite ion determination in environmental samples. A synthetic Schiff base was chosen as an ionophorein the CPE composite, showing a high affinity towards the dihydrogen arsenite ions as analyte. Using theSchiff baseas a suitable ionophore leads to a suitable selectivity for determining the dihydrogen arsenite ion in the presence of various interfering species. Besides, paraffin oil as a binder, multi-walled carbon nanotubes (MWCNTs), graphite powder were utilized as other CPE components. In this procedure, a robust experimental designbased on the simplex lattice mixture design was applied for optimising the carbon paste electrode composition. The potentiometric sensor has a linear response in the concentration range of 4.3 × 10−8-1.0 × 10−2mol L−1 and a reasonable Nernstian slope of 59.429 mV decade−1 with an R2 of 0.9917 for the dihydrogen arsenite ion determination. Various environmental samples, including tap water, river water and mineral water samples, were analysed by the sensor, showing appropriate RSD and recoveries for the dihydrogen arsenite ion measurement. The sensor’s advantages include the simple and straightforward CPE preparation, simple operation, high lifetime, fast response time, wide linearity, high selectivity, and low detection limit for determining the dihydrogen arsenite ions.

REMOVAL OF AS (III) ION FROM AQUEOUS SOLUTION USING IRON PARTICLES PREPARED FROM LEMON JUICE

The present study reports a benign approach to prepare citrate capped iron particles using juice of a lemon fruit. Resultant particles were subjected to detailed adsorption studies for removal of arsenite aqueous solution of defined concentration. The planer reflection of XRD analysis suggested that iron particles were crystalline in nature. FT-IR study suggested that functional groups like -NH2, -NO2 , -CO, and –CS were involved in arsenite ion sorption. The composite removal efficiency for As (III) was found to be 88.58 %, at pH 4.5, with contact time of 30 min and temperature at 30°C. Data of adsorption were analyzed using various parameter like isotherm models, thermodynamic and kinetic models. Chemisorptions resulted in to formation of monolayer arsenite ions over the surface of prepared iron particles with maximum adsorption capacity; 55.53 mg/gm. Adsorbent hold good promises to remove arsenic from contaminated water.

Highly selective and sensitive detection of arsenite ions(III) using a novel tetraphenylimidazole-based probe.

More than 200 million people in the world are exposed to areas where the arsenic concentration exceeds the limit allowed for living species, which urges researchers to develop low-cost methods for the selective and fast detection of arsenic ions in environmental samples. Herein, we report a novel tetraphenylimidazole-based probe (TBAB) functionalized with a Schiff base for sensing and detecting arsenic ions in aqueous media. Upon the addition of arsenic ions, an obvious fluorescence change from faint yellow to green was observed visible to the naked eye. The probe can detect arsenic selectively in the presence of interfering substances, with a lower detection limit than 0.7 ppb, a value which is far lower than the limit set by the WHO. A detailed mechanism revealed that the chelation of TBAB with arsenic activated the AIE characteristic, leading to the enhanced fluorescence, which was verified by Job's plot experiment and HRMS. Its practicality was further validated by the analysis of real water samples, demonstrating its potential application for on-site detection and biological application.

Capillary zone electrophoresis as a simple approach for the study of p-arsanilic acid transformation in the process of photolytic degradation.

Arsenic aromatic compounds including p-arsanylic acid (pASA) are still widely used in a number of countries as the feed additives in animal breeding resulting in its entering the environment. Under the influence of oxidizing agents or UV radiation, pASA undergoes transformations leading to generation of inorganic arsenic species that are more mobile and toxic than organic ones. On the one hand, an approach based on the treatment of contaminated waters by UV irradiation seems perspective for their detoxification, but the feasibility of this approach depends on the composition of the products forming as a result of photodegradation. In the present work, a CZE was applied for the study of the pASA degradation process during stationary (308nm) photolysis in the presence of Fe(III)-oxalate complex. A developed assay allowed controlling the parent compounds and also As-containing products of pASA degradation, presented mainly by arsenate and arsenite ions. It was found that the main inorganic derivatives of the pASA photolytic conversions are presented by arsenate and arsenite ions whose ratio depends on the initial amount of pASA and reaction conditions.

Improved arsenite adsorption using iron-impregnated marble dust with surface functionalized by quaternary ammonium ions

The present study investigates the application of marble dust impregnated with iron and functionalized with quaternary ammonium ions [using ammonium persulphate (APS)] as a novel adsorbent for the removal of arsenite ions from wastewater. The optimal modification parameters were found to be 0.1 M FeCl3, 0.125% NaOH (w/v) and 0.0125 M of APS at a temperature of 80 °C. The maximum uptake capacity of As(III) ions was found to be 50 mg/g with 3.5 g/L of adsorbent for 90 min at pH = 7.0. Maximum negative ∆G° value (− 7.7 kJ/mol) was obtained at 298 K, indicating that low temperature favoured adsorption. Freundlich and Temkin isotherm models gave the best correlation coefficient (R2 > 0.95). The kinetic data were suitably described by pseudo-second-order kinetics. Film diffusion was inferred to be the rate-controlling mechanism based on Boyd plots. The synthesized adsorbent can be regenerated by flushing with an alkaline solution.

SUSPENSION SORBENTS FOR REMOVAL OF ARSENIC COMPOUNDS AND HUMATES FROM WATER

This paper is devoted to the features of the synthesis and applications of suspension iron(III)-based sorbents in water treatment. The problems of toxic impurities of the drinking water, especially soluble arsenic compounds or different organic disinfection by-products, are very acute not only for Ukraine, but for many other countries too. So, it is very important to find simple and effective method to treat polluted natural waters to the required quality. The comparison of different treatment methods for removal of arsenic compounds and humates was made, as a result of which it was determined that the usage of adsorbents, especially fine particle iron-based sorbents, is very effective in natural organic matter removal and some other pollutants. Fine particle iron-based adsorbents are effective for arsenic removal due to its chemical structure. These materials removed arsenic compounds by chemisorption processes and immobilization of arsenate and arsenite ions in the insoluble form of ferric arsenate. Thus, the aim of the work was to develop the adsorbent for effective removal of arsenic compounds and humates from natural waters. We synthesized 7 suspension iron(III)-based sorbents by homogeneous precipitation from FeCl3 solution by thermal hydrolysis of urea. The efficiency of synthesized samples was checked by adsorption tests (humates and arsenite removal) and capillary suction time test. Iron(III) oxyhydroxide was the main phase of the most effective fine particle adsorbents. Applications on natural water showed that the synthesized iron(III) oxyhydroxide effectively removed arsenic compounds not only from model waters, but also from natural water with reaching of regulatory requirements.

Functionalized Single-atom Thickness Boron Nitride Membrane for Separation of Arsenite Ion from Water: A Molecular Dynamics Simulation Study

In this research, the performance of functionalized boron nitride nanosheet (BNNS) as a nanostructure membrane with single-atom thickness for the separation of arsenite ions from aqueous solution was examined by molecular dynamics simulation method. The simulated system included a functionalized BNNS placed in an ionic solution containing sodium arsenite, while the external pressures were applied to the system. For the high-water permeability and full ions rejection, the pore of BNNS was functionalized by passivizing pore edge atoms with F and H atoms. Then hydrostatic pressures in the range of 5-100 MPa was applied to the system. During the molecular dynamics simulations, water molecules and arsenite ions were monitored, and some analyses such as water flux, the density profile of water and ion, hydrogen bonds, and radial distribution function were obtained. Results showed that functionalized BNNS was able to conduct water molecules with high permeability through its pore, whereas ions were not able to pass through the pore.

Removal of Arsenic(III) Ion from Aqueous Media Using Complex Nickel-Aluminum and Nickel-Aluminum-Zirconium Hydroxides

The technology of wastewater treatment involving removal of heavy metals using complex metal hydroxides is reported. In this study, complex nickel-aluminum (NA11 and NA12) and nickel-aluminum-zirconium (NAZ1 and NAZ2) hydroxides were prepared for the removal of arsenite ions, As(III), from aqueous solution. The characteristics of each adsorbent were evaluated, and the adsorption capacity and adsorption mechanism were determined. The adsorption capacity of As(III) on NAZ1 (15.3 mg g−1) was greater than that on NA11 (9.3 mg g−1). Coverage is directly related to the specific surface area with a correlation coefficient of 0.921. Ion exchange involving sulfate ions in the interlayer of the adsorbent also plays a role in the mechanism of As(III) adsorption as demonstrated by correlation coefficients of 0.797 and 0.944 for the NA11 and NAZ1, respectively. The results demonstrate the usefulness of NAZ1 in removing As(III) from aqueous media.

Construction of arsenic-metal complexes loaded nanodrugs for solid tumor therapy: A mini review.

Arsenic trioxide (As2O3), a front-line therapeutic agent against acute promyelocytic leukemia, has a broad spectrum against malignancies. Unfortunately, the clinical application of As2O3 in treating hematological cancers has not been transformed to solid tumors, for its dose-limited toxicity and undesirable pharmacokinetics. The ordinary As2O3 loaded nanodrugs (such as liposomes, polymer micelles, albumin-based nanodrugs, and silica-based nanodrugs, etc.) still could not fuel up pharmaceuticals and eradicate toxicity for low delivery efficiency caused by the instability and severe drug leakage of formulations during circulation. Recently, the approach of forming and delivering arsenic-metal complexes which will dissociate in the tumoral environment caught our mind. This is the most effective strategy to reduce drug leakage in circulation and accumulate arsenite ions in tumor sites, therefore promote the anti-tumor effect and lighten the toxicity of the drug. This review aims to explain the formation mechanism of arsenic-metal nanocomposites and summarize the constructing strategies of the arsenic-metal nanocomplexes (arsenic-nickel, arsenic-manganese, arsenic-platinum, arsenic-gadolinium, arsenic-zinc, and arsenic-iron nanobins) loaded nanodrugs for solid tumor therapy. Furthermore, the expectations and challenges of arsenic-metal complexes containing nanodrugs for cancer therapy in the future were discussed.

Fabrication of Heavy Metal Ion FET Based Sensor for Detecting Arsenite

Arsenic is one of the toxic chemical among heavy metals. It is mostly present in ground waters at higher levels. The long term exposure of food or water to arsenic leads to cancer and heart diseases. Arsenic occurs in two oxidation states, Arsenite (As2O3, As (III)) a trivalent form and Arsenate (As2O5, As (V)) a pentavalent form. As (III) is an inorganic form which is more toxic than As (V). The detection of arsenic ion in drinking water or in any liquid form of food can be done with several laboratory equipments such as ICP-MS. The detection limit of ICP-MS for Arsenic is 0.05μg/L (10^-10M). Though these laboratory methods can be used for detecting the arsenic ion but it is very complex, costly and time consuming. In this research, we developed a methodology for detecting Arsenite ion (As2O3, As (III)). FET based ion sensor is fabricated where the gate pulse is characterized with 1500 μs pulse width and amplitude of 1 V is connected to one electrode. A steady DC bias of 2 V is applied as the drainsource voltage. The Ion Selective Membrane(ISM) is used which is immobilized on the sensing areas. This ISM contains Ionophore, Potassium tetra phenyl borate, Poly vinyl chloride, 2-Nitrophenyl octyl ether and this ISM components mixture is dissolved in Tetrahydrofuran. Sodium Arsenite (NaAsO2) is the inorganic compound which is used for detection of As (III). This solution is dropped on the sensing area which covers both ISM and gate. When Vd is supplied, we temporarily apply Vg of 0V and 1V which causes a change in current level, we define it as gain and is used as our measurement signal. The concentration range from 10^-10 M to 10^-4 M of arsenite ion can be detected. This sensor is easy to fabricate, smaller in size, high sensitivity and takes less time for detecting Arsenite. This FET based ion sensor has same detection limit comparable to ICP-MS and this sensor shows higher sensitivity than the Nernstian slope. The sensing characteristics are not affected by the interfering ions. Figure 1

Gold Nanoparticle Embedded Modified MWCNT Electrodes for Electrochemical Detection of Arsenic in Water

Email of corresponding author: dipban@iitg.ac.in : We focus on electrochemical detection of arsenite and/or arsenate in water using different kinds of electrodes made from gold nanoparticle embedded on substituted multiwall-carbon-nanotubes (MWCNT). The CNTs were functionalised with thiol groups by reaction with cysteamine. Following this, three different electrodes were fabricated using thiol substituted MWCNTs, gold nanoparticle (Au NP) embedded thiol substituted MWCNTs, and magnetite doped Au NP embedded MWCNTs. Subsequently, effect of Au NPs on the electrodes in the selectivity and sensitivity of the sensor was studied. The aforementioned experiments suggest that the affinity of the arsenite ions towards the thiol groups were found to be magnified by the integration of an optimal amount of Au NPs. Further, addition of magnetite particles in the CNT matrix made the sensor more sensitive towards arsenic detection. The working principles, mainly the change of the surface potential, of the electrodes were characterized by surface potential microscopy (SPOM) study using atomic force microscopy (AFM). The study helped in the miniaturization of the arsenic sensor using screen printed commercial electrode system with a modification of the working electrode based on requirement as stated before. Interestingly, we extracted the electrochemical response using an open source Arduino UNO based potentiostat unit, as shown in Fig. 1, to translate the concept into a portable electrochemical arsenic sensor. Keywords: Arsenite/Arsenate sensor, electrochemical, Screen printed electrode, Gold nanoparticle, Arduino UNO. Figure 1

Highly Efficient Colorimetric Sensor for Selective and Sensitive Detection of Arsenite Ion (III) in Aqueous Medium.

Highly Efficient Colorimetric Sensor for Selective and Sensitive Detection of Arsenite Ion (III) in Aqueous Medium.

Optimizacija adsorpcije arsenita na adsorbent na bazi hidroksiapatita korišćenjem adaptivnog neuro-fazi sistema

This paper describes an optimization procedure for the adsorption of arsenite ions from wastewater using the Adaptive Neuro-Fuzzy Inference System (ANFIS). The adsorbent is based on hydroxy apatite, a natural material obtained from carp (Cyprinus carpio) scales. The input parameters were the influence of pH, the temperature, the initial concentration and reaction time of arsenite adsorption while the adsorption capacity and the arsenite removal percentage were studied as the output parameters.

Selective colorimetric chemosensor for the detection of Hg2+ and arsenite ions using Isatin based Schiff's bases; DFT Studies and Applications in test strips

Three isatin appended Schiff's base chemosensors (CS1-CS3) were synthesized and characterized by FT-IR, 1H-NMR, 13 C-N MR, and LC–MS. The sensing ability of the synthesized chemosensors towards Hg2+ and AsO2− ions was established through colorimetric / UV–vis techniques and achieved detection limit at ppm levels. All chemosensors CS1-CS3 exhibited rapid colorimetric / UV–vis response with Hg2+, also, CS1 and CS3 displayed dual-ion selectivity towards AsO2− (colour changes orange to aqua-blue) and Hg2+ (from orange to colorless). The binding properties and detection limit has been examined through the UV–vis instrument. The mechanism of binding was investigated using various analytical techniques like FT-IR, UV–vis, mass and 1H-NMR titration experiments. The experimental results were supported by theoretical DFT study. The developed colorimetric chemo-sensors showed a good binding affinity towards metal ions and exhibited good linearity (R2 ≈ >0.99). Further, the developed sensors were used for test strips application to detect the Hg2+, AsO2− ions and achieved naked-eye detection at ppm levels. Hence, CS1-CS3 sensors find its practical application in efficient detection of toxic metals like Hg2+ and AsO2−.

Synthesis and application of Zn/Ce bimetallic oxides for the decontamination of arsenite (As-III) ions from aqueous solutions

Arsenic contamination has threatened water safety due to its high toxicity and carcinogenicity. Therefore, it is urgent and significant to develop simple and effective approach for dearsenification of drinking water. In present study, Zn/Ce bimetallic oxide particles of various atomic ratios were synthesized by sol-gel process and were applied for adsorption of arsenite from aqueous solutions. The Zn/Ce bimetallic oxide of atomic ratio Zn0.2:Ce0.05 shows better adsorption proficiency in comparison to their monometallic counterparts as well as synthesized bimetal oxides of other atomic ratios. Sorption behavior of arsenite on Zn/Ce bimetal oxide was investigated through batch experiments and optimum conditions were found to be pH = 7.5, adsorbent dose = 0.36 g/L, and contact time = 30 min. The arsenite adsorption data was explained by Langmuir isotherm model and maximum adsorption capacity found to reaching 88.49 mg/g at 318 K. Adsorption mechanism was interpreted using FTIR and XPS data, the former suggesting formation of bond between As(III)Zn/Ce oxide nanoparticles while, latter reveals presence of both As(III) and As(V) peak which further infer that some fraction of As(III) may be get oxidized to As(V) by O2 based on Ce3+ as electron mediation agent between As(III) and O2.

Highly adsorptive polysulfone/hydrous iron-nickel-manganese (PSF/HINM) nanocomposite hollow fiber membrane for synergistic arsenic removal

The integration of nanotechnology and membrane technology has led to the development of nanocomposite membranes that endowed with outstanding performances for arsenic removal in water system. In this study, a novel adsorptive nanocomposite membrane was fabricated by incorporating novel hydrous iron-nickel-manganese trimetal oxides (HINM) nanoparticles into polysulfone (PSf) membrane. HINM with atomic ratio of Fe:Ni:Mn of 3:2:1 was first synthesized by oxidation and coprecipitation method. The PSf/HINM membranes were fabricated by dry-jet wet spinning phase inversion technique. The physicochemical properties of the membranes were observed by contact angle goniometer, scanning electron microscope (SEM) and atomic force microscope (AFM). H1.5 PSf/HINM membrane shows maximum adsorption capacity of 41.90 mg/g and water flux of 173.82 L/m2 h.bar. This membrane was fabricated by impregnating 1.5 wt% of HINM nanoparticles within 18 wt% of PSf, 5% PVP, and 78% NMP solution. The experimental data of arsenite adsorption were best fitted into pseudo-second order and Freundlich isotherm models. The mechanism of arsenite removal on PSf/HINM membrane involved both chemisorption and physisorption. Chemisorption is concerned to hydroxyl substitution by arsenite ions through the formation of inner-sphere complex, while physisorption associated to electrostatic attraction between arsenite ions and the surface charge of HINM nanoadsorbents. Leaching test demonstrated that HINM was stably incorporated within the membrane matrix. Continuous adsorption-filtration study showed that H1.5 membrane has successfully treated arsenic contaminated water to meet the maximum level (0.01 mg/L) set by World Health Organization (WHO). The membrane could be easily regenerated using 0.1 M NaOH solution. Hence, development of adsorptive nanocomposite PSf/HINM membrane is a promising solution for synergistic arsenic removal in water system due to both adsorption and filtration properties of the membrane.

Application of Modified Bentonites for Arsenite (III) Removal from Drinking Water

Four modified bentonites (La(III), Ce(III), Y(III), Fe(III)) were prepared by ion exchange process to remove arsenite (III) ions from water. The modified bentonites were examined with X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD). The rare earth (REE) and Fe(III) ion content in bentonite was higher than the CEC values obtained by ammonium acetate method related to trivalent ions (2.7 x 10-4 mol g-1). The kinetics, equilibrium time, sorption isotherms and desorption experiments were examined. Lanthanum, yttrium and cerium bentonite can bind similar amount of arsenite(III) ions. Iron-bentonite cannot bind significant amounts of arsenite ions. The active sites and the solubilities of the sorption complex were determined. Arsenite (III) ions sorb in the interlayer space as REEAsO3. The solubility of the arsenite complex was two orders of magnitude smaller than that of the phosphate complex. After desorption the eluted amount of arsenite (III) was 55 % related to the sorbed amount of arsenite. The d(001) basal spacing of modified bentonites and that of after sorption and desorption was measured. After the sorption of arsenite ion on lanthanum bentonite, the d(001) basal spacing of montmorillonite was decreased and after desorption an increase in d(001) basal spacing was observed again. Modified bentonites can be used for removing arsenic ions from water.

Adsorption/desorption of arsenite and arsenate on chitosan and nanochitosan.

Equilibrium sorption studies of anionic species of arsenite, As(III) ions and arsenate As(V) ions onto two biosorbents, namely, chitosan and nanochitosan, have been investigated and compared. The results and trends in the sorption behavior are novel, and we have observed during the sorption process of the As(III) and As(V) on chitosan, a slow process of desorption occurred after an initial maximum adsorption capacity was achieved, before reaching a final but lower equilibrium adsorption capacity. The same desorption trend, however, is not observed on nanochitosan. The gradual desorption of As(III) and As(V) in the equilibrium sorption on chitosan is attributed to the different fractions of the dissociated forms of arsenic on the adsorbent surface and in solution and the extent of protonation of chitosan with the changing of solution pH during sorption. The change of solution pH during the sorption of arsenite ions on chitosan was also influenced by the interaction between the buffering effect of the arsenite species in the aqueous medium and the physical properties of chitosan. The final equilibrium adsorption capacity of chitosan for As(III) and As(V) was found to be around 500 and 8000μg/g, respectively, whereas the capacities on nanochitosan are 6100 and 13,000μg/g, respectively.