ARSENATE REMOVAL FROM WATER USING RICE STRAW-DERIVED-BIOCHAR: A STUDY AT LOW SOLUTION CONCENTRATIONS

Abstract

This study assessed the removal of As(V) in aqueous solution at low concentrations using rice straw-derived-biochar. Biochar was produced from rice straw at 450^oC in 2 hours, then modified with acid. The product was characterized and used for adsorption experiments in order to evaluate the influencing factors and kinetics of the adsorption process for As(V). The results showed that acid-modified rice straw-derived-biochar had good adsorption capacity in the pH range of 4 - 8. The adsorption process reached equilibrium after 24 hours. The pseudo-first-order kinetic model and the Freundlich isotherm adsorption model were suitable to describe the adsorption process of the biochar for As(V). The adsorption capacity at equilibrium achieved from the pseudo-first-order kinetic model was 0.050 mg/g at pH 3 and 0.033 mg/g at pH 7. The adsorption of As(V) was significantly affected by the presence of nitrate ions in aqueous solutions.