Arsenic Removal Behavior by Fe-Al Binary Oxide: Thermodynamic and Kinetic Study

In this study, thermodynamic and kinetic behaviors of As(V) and As(III) adsorption on Fe-Al binary oxide were investigated. Adsorptions of both As(V) and As(III) on Fe-Al binary oxide were exothermic reactions (Delta H-0 < 0) and occurred spontaneously (Delta G(0) < 0). Because of strong electrostatic interaction between the As(V) anion and the positive Fe-Al binary oxide, As(V) was adsorbed rapidly and the adsorption rate was controlled by chemical adsorption. On the other hand, As(III) exists in a nonionic form, because of which it was not adsorbed through strong attractive forces. Therefore, the adsorption rate of As(III) was controlled by a combination of diffusion processes and chemical sorption.