Arsenic adsorption by activated biochar derived from water hyacinth

Abstract

This study investigates the effectiveness of water hyacinth-derived biochar in removing As(V) from low-concentration aqueous solutions, similar to groundwater, and examines the impact of elevated NO3− concentrations. Biochar was produced by pyrolyzing water hyacinth at 550 °C for 2h and subsequently modified with KOH and FeCl3 solutions. The modified biochar was characterized and employed in adsorption experiments to examine the factors influencing the adsorption process and its kinetics for As(V). Findings indicated that biochar modified with Fe showcased a robust adsorption capacity across a broad pH range of 3–10. The adsorption equilibrium was attained within 1h. The adsorption kinetics were aptly described by the pseudo-first-order kinetic model, and the Freundlich isotherm adsorption model was found suitable for characterizing the adsorption process for As(V) using biochar. The equilibrium adsorption capacity, as predicted by the pseudo-first-order kinetic model, was 203 μg g−1 at pH 7. The presence of nitrate ions had a negligible impact on As(V) adsorption. The material demonstrated the capability for reuse up to three times for As(V) removal.