Adsorbent For Arsenic Removal Research Articles

Adsorptive removal of arsenic in saturated sand filter containing amended adsorbents

In this study, adsorptive removal of arsenic in saturated sand filters (SSF(a) and SSF(b)) containing raw and iron-coated honeycomb briquette cinders (HBC and Fe-HBC) is presented. Operating parameters including SSF design, dissolved oxygen (DO), pH, iron leaching and the effects of co-occurring ions on arsenic removal were investigated at 23±2.0°C temperature for 24-days long treatment. Sampling times (ST) (5–120min) during treatment days (TD) 1, 6, 12, 18 and 24 were purposively decided to assess filters’ performance from tap water with the spiked of 200μg/L of As(V) and As(III) into SSF(a) and SSF(b), respectively. No other alteration or pH adjustment was made to the influent water. Results demonstrated that the removal efficiencies of arsenic in SSF(a) and SSF(b) were maintained >95% and >85% till TD-12 and than decreased to 78% and 60%, respectively, on TD-24. Lower arsenic removal in SSF(b) could be the result of As(III) slower oxidation at the studied influent pH under oxic conditions. Decreased in effluent DO and increased iron leaching were measured in both the filters from TD-1 to TD-24. Minor variations of effluents pH and co-occurring ions (Fluoride, Nitrate and Sulphate) were recorded, but no significant effect on arsenic removal was measured in the reported ranges. Performance of NaOH-regenerated filter-beds was evaluated and both filters removed 95% of arsenic in three-cycle treatments. This study suggests of an in situ treatment; by the oxidation of As(III) into As(V) in the presence of DO and hydroxyl radical on adsorbent surfaces, followed by subsequent adsorption through selective physical sorption and Fe-As complexation. SSF containing cost-effective adsorbents could be an effective in situ treatment option to conventional treatment for safe drinking water production.

Oxidized and Ethylenediamine-Functionalized Multi-Walled Carbon Nanotubes for the Separation of Low Concentration Arsenate from Water

In this work multiwalled carbon nanotubes (MWCNTs) modified by oxidation (o-MWCNTs) and by aminofunctionalization (e-MWCNTs) were examined as potential adsorbents for arsenate removal from water. Adsorption characteristics of raw and modified MWCNTs were investigated in batch adsorption experiments. The influence of solution pH (pH range 3–10), contact time, and temperature (25, 35, and 45°C) were studied. Ethylenediamine-functionalized MWCNTs have the greatest affinity for arsenate ions, followed by o-MWCNTs and raw-MWCNTs. The obtained experimental data for raw- and o-MWCNTs fitted Sips isotherm model, while for the e-MWCNTs, the Freundlich model provided the best fit to the experimental points. The maximum adsorption capacity for arsenate ions was achieved using e-MWCNTs, 12.18 mg g−1. The presence of the arsenate on the adsorbent is confirmed by FTIR spectroscopy. Thermodynamic studies indicated the spontaneity and endothermic nature of the adsorption. Sodium hydroxide solution (0.1 M) was found to desorb about 70% of arsenate from e-MWCNTs. The results with spiked drinking water samples demonstrated that e-MWCNTs, due to the present basic and acidic groups, were very efficient for the removal of arsenate ions, as well as of some cations, at pH 4.

Preparation of Mn-Fe Binary Oxide for Arsenic Removal from Aqueous Solution

Adsorption removal of arsenic from contaminated drinking water was carried out by using Mn-Fe binary oxide adsorbent. Main phase of adsorbents was influenced by pH value of solution, and pH of 10 is the suitable synthesis condition to achieve the Mn-Fe binary oxide suspension adsorbents. Adsorbents with Mn/Fe mole ratio from 6/4 to 2/8 exhibits higher arsenite removal larger than 99.6%.

Magnetic iron oxide nanoparticles prepared by electrical wire explosion for arsenic removal

Abstract Electrical wire explosion (EWE) is a simple and clean process to produce metal nanoparticles. In this study, EWE was employed to synthesize iron oxide nanoparticles to examine their potential as adsorbents for arsenic removal from water. The explosion of iron wire in air produced magnetic iron oxide nanoparticles composed of magnetite (55.8 wt%) and maghemite (44.2 wt%) without antiferromagnetic hematite or wustite phases. The average particle size was 34 nm, and the saturation magnetization was 91.9 emu/g. The arsenic adsorption experiment revealed that the maximum adsorption capacity, q max , for As(III) and As(V) was 2.90 and 3.05 mg/g (0.25 and 0.27 mg/m 2 ), respectively. We have demonstrated that EWE is a useful alternative method for the one-step production of magnetic iron oxide nanoparticles, which can be used as adsorbents in arsenic removal from water.

Optimisation of sugar cane activated carbon for arsenic(V) and arsenic(III) removal from water

This paper addresses the development of low-cost adsorbents for removal of arsenic from water in support of mitigation programmes in low and middle income countries. Activated carbon (AC) is a well established water treatment technology, but has high cost and low selectivity in respect of arsenic. AC made from agricultural by-products is a low-cost alternative to coal-based AC. In this study, the preparation parameters of sugar-cane activated carbon (SCAC) were optimised for arsenic(V) and arsenic(III) adsorption. The effect of preparation parameters on arsenic removal was investigated with a 23 factorial experiment. SCAC was characterised by the pH of zero charge, surface area, pore width distribution, particle size distribution and imaging under scanning electron microscopy. Activation temperature (AT) has a profound effect on arsenic adsorption; arsenic(V) adsorption increased from 2.8% at an AT of 873 K to 87.6% at an AT of 1,173 K. The percentage of arsenic removal from water has a strong positive correlation with surface area, and a strong negative correlation with micropore/pore volume ratio and the percentage in volume of particles with a size of 60–2,000 μm. In conclusion, this research shows that low-cost AC can be manufactured for removal of target pollutants, such as arsenic, from water.

One-pot, large-scale synthesis of magnetic activated carbon nanotubes and their applications for arsenic removal

We report a one-pot method to synthesize magnetic iron oxide/CNT composites (MI/CNTs) based on as-prepared CNTs (APCNTs) using KOH activation. MI/CNTs have high specific surface area, good dispersion and magnetic properties, making them promising for use as adsorbents for arsenic removal. The results of this work are highly significant for large-scale applications of APCNTs containing Fe catalytic particles without the need for prior purification.

Microwave-Assisted Preparation and Physical Characterisation of Iron Oxyhydroxides Adsorbents for Arsenic Removal from Aqueous Solutions

A novel method for preparation of iron oxyhydroxide materials, involving aqueous precipitation followed by microwave assisted aging is investigated. The produced materials are characterized by XRD, SEM, EDX and TEM spectroscopy and BET analysis. The materials show physical characteristics dependent on preparation procedure. The adsorptive properties of the materials for arsenic are studied by batch adsorption techniques. It is found that the rate of arsenic upload depends strongly on the degree of crystallinity of the materials. The adsorption capacity is approximately 55 mg/g. The physical characterization of the arsenic loaded adsorbents show that the adsorption process modifies the morphology of the materials. Over 4% of arsenic atoms are incorporated into the particle matrix.

Arsenic Removal from Water by Adsorption Using Iron Oxide Minerals as Adsorbents: A Review

This review highlights the adsorption process by using iron oxide minerals as the adsorbent for arsenic removal from water. It includes the characteristics of arsenic in water and its toxicities, the adsorption process for arsenic removal from contaminated water, iron oxide minerals as the adsorbent, arsenic adsorption capacity on iron oxide minerals, main factors of the adsorption, and arsenic removal from water by the adsorption process, as well as the mechanisms by which arsenic species adsorb on iron oxide minerals.

Maghemite nanoparticles for As(V) removal: desorption characteristics and adsorbent recovery

Maghemite (γ-Fe2O3) nanoparticles are potential adsorbents for arsenate removal from drinking water. Arsenate, As(V) oxoanion, removal is crucial due to arsenate's serious effects on health and its existence in water worldwide. The aim of the present study was to investigate the adsorbent properties of maghemite nanoparticles by observing their stability, desorption and regeneration ability. Arsenate batch desorption and regeneration experiments were carried out with two different kinds of maghemite – a commercial product and a laboratory-synthesized one using the sol-gel process. The best alkaline desorption solution was determined from five different alkaline solutions: NaOH, Na2CO3, Na2HPO4, NaHCO3 and CH3COONa·3H2O (NaAc). Desorption kinetics were also examined. NaOH was observed to be the best desorption solution at a concentration of 1 M with>95% desorption efficiency achieved for both adsorbents. The arsenate adsorption–desorption process was reversible and maghemite recovery was efficient at successive cycles. The laboratory-synthesized maghemite maintained more than 95% of its initial uptake capacity after six cycles for initial As(V) concentrations of 500 and 1000 μg/l, while the achievement with the commercial product was two to four cycles. In addition, iron dissolution from adsorbents was negligible. Thus, it is possible to regenerate the maghemite nanoparticles for repeated adsorption of As(V).

Iron and 1,3,5-Benzenetricarboxylic Metal–Organic Coordination Polymers Prepared by Solvothermal Method and Their Application in Efficient As(V) Removal from Aqueous Solutions

Iron and 1,3,5-benzenetricarboxylic (Fe–BTC) metal–organic coordination polymers are synthesized via a simple solvothermal method. The as-synthesized Fe–BTC polymers exhibit gel behavior, which is stable in common organic solvents or in water. The Fe–BTC polymer as an adsorbent for arsenic removal from water is tested. The kinetics and thermodynamics of arsenic adsorption by the Fe–BTC polymer in aqueous solution are investigated comprehensively. The effect of pH on the adsorption is also investigated. Kinetic studies show that the kinetic data are well described by the pseudo-second-order kinetic model. The thermodynamic analysis indicates that the adsorption is spontaneous. The adsorption isotherms can be well described with the Langmuir equation. The Fe–BTC polymers show relatively high arsenic adsorption capacity, more than 6 times that of iron oxide nanoparticles with a size of 50 nm and 36 times that of commercial iron oxide powders. Hence, the as-synthesized Fe–BTC polymers possess relatively high ...

Superparamagnetic high-surface-area Fe3O4 nanoparticles as adsorbents for arsenic removal

Superparamagnetic ascorbic acid-coated Fe3O4 nanoparticles with a high specific surface area were successfully synthesized via an environmentally friendly hydrothermal route in the absence of any templates. The as-synthesized ascorbic acid-coated Fe3O4 nanoparticles have a diameter of less than 10nm, thus leading to a high specific surface area of about 179m2/g, which is even larger than those of well-defined mesoporous structures. The only used capped agent is ascorbic acid, which serves as a functionalized molecule to make sure the high dispersibility and stability of the ascorbic acid-coated Fe3O4 nanoparticles in aqueous solution. The ascorbic acid-coated Fe3O4 nanoparticles exhibit superparamagnetic properties at room temperature and saturation magnetization approaches 40emug−1. The ascorbic acid-coated Fe3O4 nanoparticles were evaluated as an absorbent to remove heavy metal arsenic from wastewater. The adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 16.56mg/g for arsenic (V), and 46.06mg/g for arsenic (III).

Adsorptive removal of arsenic(III) ions from industry wastewaters using a weak anion exchanger prepared from banana stem

AbstractThe performance of an anion exchanger prepared from banana stem (BS), a lignocellulosic residue for the removal of As(III) from aqueous solutions has been evaluated in this study. The adsorbent (BS‐DMAHP) containing dimethylaminohydroxypropyl (DMAHP) functionality was prepared by the reaction of BS with epichlorohydrin and dimethylamine followed by treatment with hydrochloric acid to convert it into the chloride form of the anion exchanger. The adsorbent characterization was done with the surface area analyzer, Fourier transform infrared spectroscopy (FTIR), and potentiometric titrations. Adsorption equilibrium study was conducted with a concentration range of 10–300 mg/L, for As(III). The Langmuir isotherm model was found to be the best fit model. The maximum adsorption capacity was found to be 65.11 mg/g. Adsorption has been found to be endothermic and follows second‐order reversible kinetics. The removal efficiency of BS‐DMAHP was also compared with commercially available amine functionalized weak base anion exchanger, Duolite A‐7. Regeneration studies were also conducted to evaluate the reusability of the adsorbent. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Adsorption of arsenic on multiwall carbon nanotube–zirconia nanohybrid for potential drinking water purification

The adsorptive removal of arsenic from water using a multiwall carbon nanotube–zirconia nanohybrid (MWCNT–ZrO2) is presented. The MWCNT–ZrO2 with 4.85% zirconia was effective in meeting the drinking water standard levels of 10μgL−1. The absorption capacity of the composite were 2000μgg−1 and 5000μgg−1 for As(III) and As(V) respectively, which were significantly higher than those reported previously for iron oxide coated MWCNTs. The adsorption of As(V) on MWCNT–ZrO2 was faster than that of As(III), and a pseudo-second order rate equation effectively described the uptake kinetics. The adsorption isotherms for As(III) and As(V) fitted both the Langmuir and Freundlich models. A major advantage of the MWCNT–ZrO2 was that the adsorption capacity was not a function of pH.

Removal characteristics of As(III) and As(V) from acidic aqueous solution by steel making slag

This study focused on the environmental risk of steel making slag itself, arsenic removal mechanism and re-leaching possibility of arsenic to aqueous state after the adsorption. The purpose of the study is to promote the use of steel making slag as a low-cost adsorbent for arsenic in aqueous system. Calcium was easily dissolved out from the slag and become the dominant substance in the leachate. Some of the calcium could form amorphous calcium carbonate in alkaline condition, and arsenic in the aqueous solution would be removed by being co-precipitated with or adsorbed onto the amorphous calcium carbonate. Most of the amorphous calcium carbonate containing arsenic would be bound to amorphous iron oxide of the slag. When the slag was used as an adsorbent for arsenic removal, a little amount of toxic chemicals were leached from the slag itself under pH 0.8 to 13.6. Also, 70–80% of arsenic laden on the slag was bound to amorphous iron oxide which would not easily desorb unless given a reducing and complexing condition. Showing 95–100% removal efficiency near initial pH 2, the slag, therefore, could be used as an appropriate adsorbent for eliminating arsenic in acidic aqueous solution.

Mn–Fe Layered Double Hydroxides for Adsorption of As(III) and As(V)

Arsenic pollution in drinking water or surface water has become a worldwide environmental issue and is a serious threat to human health. In this study, Mn–Fe–CO3 layered double hydroxides (LDHs) were prepared by the co-precipitation method, for the removal of As(III) and As(V) from solutions. The physical and chemical characteristics of LDHs were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). As(III) and As(V) adsorption capacities and the mechanism of metal removal by LDHs were determined by batch and column experiments. The results indicate that LDHs are novel and excellent adsorbents for arsenic removal.

Arsenic adsorption using copper (II) oxide nanoparticles

Arsenic poisoning is a major problem in today's life. To reduce its concentration in drinking water, different metal based compounds were explored as arsenic adsorbents. In the present study, copper (II) oxide nanoparticles were prepared by thermal refluxing technique and used as an adsorbent for arsenic removal from water. Characterization of the adsorbent using TEM, BET, XRD and FTIR implied that the prepared adsorbent was in nano size and had excellent adsorption behavior with surface area of 52.11m2/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed and found that copper (II) oxide had very good efficiency towards arsenic adsorption. Thermodynamic parameters and adsorption kinetics were studied in detailed to know the nature and mechanism of adsorption. Results showed that the adsorption process followed pseudo second order kinetic and endothermic behavior. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 1086.2μg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation is reported to know the amount of adsorbent required for efficient removal of arsenic from aqueous medium.

Removal of arsenic from water using the adsorbent: New Zealand iron-sand

Adsorption is a technology used to remove arsenic from water contaminated at levels above drinking water standards. In this study, New Zealand Iron-Sand (NZIS), a naturally-available adsorbent was investigated for its efficiency in removing both As (III) and As (V). Several batch tests were conducted with different concentrations of arsenic at different pH conditions. During the batch tests, the maximum adsorption of As (III) occurred at a pH of 7.5, while As (V) adsorption reached its maximum value at a pH of 3. Both Langmuir and Freundlich adsorption models were found to fit with R2 values greater than 0.92. From the Langmuir adsorption model, the maximum adsorption capacity of NZIS for As (III) and As (V) were estimated to be 1,250 and 500 μg/g, respectively. These values were substantial enough to consider NZIS a promising new adsorbent for arsenic removal.

Removal of arsenic from water by Friedel's salt (FS: 3CaO·Al 2O 3·CaCl 2·10H 2O)

Low levels of arsenic can be effectively removed from water by adsorption onto various materials and searching for low-cost, high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of Friedel's salt (FS: 3CaO·Al 2O 3·CaCl 2·10H 2O), a layered double hydroxide (LDHs), as an adsorbent for arsenic removal from aqueous solution was investigated. Friedel's salt was synthesized at lower temperature (50 °C) compared to traditional autoclave methods by reaction of calcium chloride with sodium aluminate. Kinetic study revealed that adsorption of arsenate by Friedel's salt was fast in the first 12 h and equilibrium was achieved within 48 h. The adsorption kinetics are well described by second-order Lageren equation. The adsorption capacity of the synthesized sorbent for arsenate at pH 4 and 7 calculated from Langmuir adsorption isotherms was 11.85 and 7.80 mg/g, respectively. Phosphate and silicate markedly decreased the removal of arsenate, especially at higher pH, but sulfate was found to suppress arsenate adsorption at lower pH and the adverse effect was disappeared at pH ≥ 6. Common metal cations (Ca 2+, Mg 2+) enhanced arsenate adsorption. The results suggest that Friedel's salt is a potential cost-effective adsorbent for arsenate removal in water treatment.

Adsorptive removal of arsenic from aqueous solution by a PVDF/zirconia blend flat sheet membrane

The groundwater contaminated with arsenic is often associated with unwanted natural organic matters and microorganisms. It is therefore important to develop multi-functional technologies for the treatment of groundwater. In this study, a PVDF/zirconia blend flat sheet membrane was prepared so that it could adsorb arsenate and remove other contaminants such as microorganisms. The crystal structure, hydrophobicity, porosity, water flux and arsenic adsorption capacity of the membrane were investigated. The PVDF was α-form and the zirconia was amorphous in the membrane. The addition of zirconia increased the hydrophilicity and porosity of the membrane, which led to a significant enhancement in the water flux of membrane. The batch adsorption experiments demonstrated that the membrane effectively removed arsenate in a wide optimal pH ranging from 3 to 8. The adsorption equilibrium could be established in 25 h, and the maximum adsorption capacity was 21.5 mg/g, comparable to most of the available adsorbents. Co-anions such as fluoride did not obviously affect the adsorption. In addition, the membrane was efficient for removal of arsenate and bacteria ( Escherichia coli) under continuous filtration. The membrane saturated by arsenate could be easily regenerated using an alkaline solution and subsequently be reused. Finally, a potential interaction mechanism between the membrane and arsenate was proposed based on the results obtained from FTIR and XPS studies.

Adsorptive removal of arsenic from water by an iron–zirconium binary oxide adsorbent

Arsenate and arsenite may exist simultaneously in groundwater and have led to a greater risk to human health. In this study, an iron–zirconium (Fe–Zr) binary oxide adsorbent for both arsenate and arsenite removal was prepared by a coprecipitation method. The adsorbent was amorphous with a specific surface area of 339 m 2/g. It was effective for both As(V) and As(III) removal; the maximum adsorption capacities were 46.1 and 120.0 mg/g at pH 7.0, respectively, much higher than for many reported adsorbents. Both As(V) and As(III) adsorption occurred rapidly and achieved equilibrium within 25 h, which were well fitted by the pseudo-second-order equation. Competitive anions hindered the sorption according to the sequence PO 4 3 - > SiO 3 2 - > CO 3 2 - > SO 4 2 - . The ionic strength effect experiment, measurement of zeta potential, and FTIR study indicate that As(V) forms inner-sphere surface complexes, while As(III) forms both inner- and outer-sphere surface complexes at the water/Fe–Zr binary oxide interface. The high uptake capability and good stability of the Fe–Zr binary oxide make it a potentially attractive adsorbent for the removal of both As(V) and As(III) from water.