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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY, vol.20, no.2, pp.732-738, 2014 (SCI-Expanded)
The sorptive removal of arsenic from water by synthetically-prepared magnetic Fe-hydrotalcite (M-FeHT) seeding by nano magnetite was investigated. The synthesis of M-FeHT was achieved by a co-precipitation method. M-FeHT was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetic susceptibility analysis. Batch tests were conducted to investigate the removal mechanism of As(III) and As(V) by M-FeHT. Kinetic studies revealed that uptake of As(V) (95% removal) and As(III) ions occurs rapidly within the first 15 min, and slows thereafter. The adsorption data follow a pseudo-second-order kinetic model and fit the Langmuir isotherm well. The experimental results show that stable arsenic removal efficiency, and the capability to reduce As levels, make M-FeHT a suitable adsorbent for the treatment of As-polluted waters. After adsorption, tests were conducted with magnetic separation to determine the separability of M-FeHT from solution. At magnetic field intensity of 2 T, the efficiency of M-FeHT separation was 91%. Finally, after adsorption by M-FeHT, residual arsenic concentration decreased to less than 10 mu g/L (i.e., below the threshold specified by the WHO). Fe-hydrotalcite-supported magnetite nanoparticles were not only more efficient in the removal of As but also in recovery by the magnetic separator. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.