Arsenite and arsenate adsorption on coprecipitated bimetal oxide magnetic nanomaterials: MnFe2O4 and CoFe2O4. Chemical Engineering Journal, 158, 599-607

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China
Chemical Engineering Journal (Impact Factor: 4.32). 04/2010; 158(3):599-607. DOI: 10.1016/j.cej.2010.02.013


Bimetal oxide magnetic nanomaterials (MnFe2O4 and CoFe2O4) were synthesized and characterized with transmission electron microscope (TEM), X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). The adsorption of arsenic on these nanomaterials was studied as a function of pH, initial arsenic concentration, contact time and coexisting anions. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data, and the maximum adsorption capacities of arsenite (AsIII) and arsenate (AsV) on MnFe2O4 were 94 and 90 mg g−1, and on CoFe2O4 were 100 and 74 mg g−1, respectively. MnFe2O4 and CoFe2O4 showed higher AsIII and AsV adsorption capacities than the referenced Fe3O4 (50 and 44 mg g−1, respectively) prepared by the same procedure. Quantificational calculation from XPS narrow scan results of O(1s) spectra of adsorbents indicated that the higher adsorption capacities of AsIII and AsV on MnFe2O4 and CoFe2O4 than on Fe3O4 might be caused by the increase of the surface hydroxyl (M–OH) species. Phosphate and silicate were powerful competitors with arsenic for adsorptive sites on the adsorbent. Desorption study showed that over 80% of AsIII and 90% of AsV could be desorbed from MnFe2O4 with 0.1 M NaOH solution.

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    • "Recently, magnetic bimetal oxide nanoparticles, which introduce a second suitable metal into the Fe-containing materials, have received increasing attention because they combine the respective advantages of each component, conferring enhanced properties in comparison to their monometallic nanoparticle counterparts [15] [16], and also have significantly enhanced heterogeneous catalysis activity. As one of the most important rare earth metal oxides, cerium has been extensively studied because of its redox and catalytic properties, which enhance the performance of the transition metal catalysts used in automotive exhaust treatment and wastewater treatment [17] [18]. "
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    ABSTRACT: Magnetic mesoporous iron cerium bimetal oxides (MMIC) with large surface area and pore volume was synthesized via the hard template approach. This obtained MMIC was easily separated from aqueous solution with an external magnetic field and was proposed as a heterogeneous Fenton-like catalyst for oxidation of As(III). The MMIC presented excellent catalytic activity for the oxidation of As(III), achieving almost complete oxidation of 1000ppb As(III) after 60min and complete removal of arsenic species after 180min with reaction conditions of 0.4g/L catalyst, pH of 3.0 and 0.4mM H2O2. Kinetics analysis showed that arsenic removal followed the pseudo-first order, and the pseudo-first-order rate constants increased from 0.0014min(-1) to 0.0548min(-1) as the H2O2 concentration increased from 0.04mM to 0.4mM. On the basis of the effects of XPS analysis and reactive oxidizing species, As(III) in aqueous solution was mainly oxidized by OH radicals, including the surface-bound OHads generated on the MMIC surface which were involved in Fe(2+) and Ce(3+), and free OHfree generation by soluble iron ions which were released from the MMIC into the bulk solution, and the generated As(V) was finally removed by MMIC through adsorption. Copyright © 2015 Elsevier B.V. All rights reserved.
    Journal of Hazardous Materials 01/2015; 287C:225-233. DOI:10.1016/j.jhazmat.2015.01.065 · 4.53 Impact Factor
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    • "Much larger Q m value of PS-Fe 3 O 4 further demonstrated that nano-Fe 3 O 4 particles , after being coated upon PS beads, were better dispersed and exhibited more active sites for arsenate adsorption. Zhang et al. [25] reported the maximum arsenate adsorption capacities of Fe 3 O 4 with diameter of ∼20 nm was 44 mg/g. Yavuz et al. [6] [7] [8] found that for As(V) removal, the maximum adsorption capacity of "
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    ABSTRACT: Fe(3)O(4) is a promising material for arsenic sequestration due to its specific affinity toward arsenic and feasible magnetic separation. How to further increase its adsorption capacity while maintain its low-field separation is an interesting but challenging task. In this study nano-Fe(3)O(4) was successfully coated onto the outer surface of polystyrene (PS) beads of 350-400nm in diameter by the hetero-coacervation method, and the resulting composite PS-Fe(3)O(4) was characterized using transmission electron microscope (TEM), X-ray powder diffraction (XRD), and electrophoresis measurement (EM). Its adsorption toward arsenate was investigated as a function of solution pH, arsenic concentration, contact time, and coexisting anions. The maximum adsorption capacity of PS-Fe(3)O(4) was 139.3mg/g Fe(3)O(4), 77.7% greater than that of bulky Fe(3)O(4). More attractively, it can be readily separated from water under a low magnetic field (<0.035T). Continuous adsorption-desorption cyclic results demonstrated that arsenate-loaded PS-Fe(3)O(4) can be effectively regenerated by NaOH solution, and the regenerated composite beads could be employed for repeated use without significant capacity loss, indicating that nano-Fe(3)O(4) was steadily coated onto the surface of PS beads. Generally, PS beads could be employed as a promising host to fabricate efficient composites originated from Fe(3)O(4) or other nanoparticles for environmental remediation.
    Journal of hazardous materials 10/2012; 243. DOI:10.1016/j.jhazmat.2012.10.036 · 4.53 Impact Factor
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    • "Natural arsenic (As) contamination in water supplies is a major environmental and health problem on a global scale and has become a challenge for the world scientists. Increasing concentrations of arsenic in groundwater and surface water have been reported from many regions of the world in recent years [1] [2] [3] [4] [5] [6] [7]. "
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    ABSTRACT: In the present study, we synthesized calcium peroxide nanoparticles and evaluated them as an innovative oxidant to remove As (III) from contaminated water samples. The CaO 2 nanoparticles were 15–25 nm in diameter identified by TEM. Oxidation occurred within minutes and CaO 2 nanoparticles effectively removed total As between natural pH conditions (6.5 and 8.5). Experiments were performed to investi-gate the influence of CaO 2 nanoparticles concentration, pH of solution and contact time on the efficiency of arsenic removal. Up to 88% removal efficiency for arsenic was obtained by nanoparticles dosage of 40 mg/L at time equal to 30 min and pH 7.5. It could be concluded that the removal efficiency was enhanced by increasing CaO 2 nanoparticles dosage and reaction time, but decreased by increasing arsenic concentration and pH for nano sized CaO 2 . These results suggest that CaO 2 nanoparticles may be used to develop a simple and efficient arsenic (III) removal method. Ó 2012 Elsevier B.V. All rights reserved.
    Separation and Purification Technology 07/2012; 95:10-15. DOI:10.1016/j.seppur.2012.04.021 · 3.09 Impact Factor
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