Determination of arsenic(III) and arsenic(V) binding to microwave assisted hydrothermal synthetically prepared Fe3O4, Mn3O4, and MnFe2O4 nanoadsorbents

The potential of the Fe3O4, Mn3O4, and MnFe2O4 nanophases for the removal of arsenic(III) and (V) from aqueous solutions was investigated using the batch technique. The structure and grain size of the nanoadsorbents were characterized using XRD and Secherrer's equation. The Fe3O4, Mn3O4, and MnFe2O4 had the crystal structure of magnetite, hausmannite, and Jacobsite, while the grain sizes were 28, 25, and 12 nm, respectively. It was found that the sorption determined using 100 ppb of either As(III) or (V) was pH independent from pH 2 through pH 6. However, at pH below 3 the nanomaterials released high concentrations of iron and manganese into solution. The amount of both As(III) and (V) per gram of adsorbent was found to increase with increasing concentration of As in solution. The XRD analysis showed no decrease in the average grain size of the nanoadsorbents reacted with 1000 ppm of either As(III) or (V) or a combination of 500 ppm of each As species. Finally Fe3O4, Mn3O4, and MnFe2O4 showed binding capacities (mu g/g) of 32.2, 8.9. and 718 for As(III) and 1575, 212 and 2125 for As(V). respectively. (C) 2008 Elsevier B.V. All rights reserved.