2017 Volume 43 Issue 4 Pages 193-198
Removal of arsenite (As(III)) and arsenate (As(V)) from aqueous solution by Fe–Al composite oxides as adsorbents was investigated. Fe–Al composite oxides were synthesized by calcination of precursors containing Fe3+ and Al3+ hydroxides prepared by co-precipitation. Various composite oxides were prepared, and the effects of pH and the ratio of Fe and Al on the removal of arsenic, and the simultaneous removal of As(III) and As(V) from solution were investigated. Composite oxides calcined below 500°C were found to be typically amorphous, and the results of specific surface area and As removal indicated that calcination at 300°C was appropriate. At a molar ratio of Fe : Al=1 : 1, both As(III) and As(V) were effectively removed. In particular, As(V) removal was drastically improved by the synergistic effect of complex of Fe3+ and Al3+. The adsorption isotherms of As(III) and As(V) were of Freundlich type and Langmuir type, respectively. Simultaneous removal tests at different As(III)/As(V) ratios showed that the composite oxide synthesized at Fe : Al=1 : 1 and 300°C had excellent removal ability.