The Application of Eco-Friendly Fe–Al Bimetallic Oxide/Biochar Adsorbent Composites with Waste Rice Husk for Removal of Arsenic at Low Concentration

Arsenic-contaminated water with low concentration is a worldwide problem because of its inevitable toxicity. Therefore, it is of practical significance to develop an economical and environment-friendly adsorbent for arsenic removal. In this work, an eco-friendly Fe–Al bimetallic oxide/biochar adsorbent composites was successfully synthesized from discarded rice husk. The factors of different pH, reaction time, initial concentration and interfering ions were studied to further explore adsorption effect by adsorbent in low concentration arsenic solution. The results indicated that the adsorbent had the excellent adsorption capacity at 60 °C and phosphate has the greatest interference to the adsorption process among the selected five interfering ions. The experimental data are fitted to the adsorption isotherm and kinetic model, and the results are more consistent with Ferundlich model and pseudo-first-order kinetic model. Furthermore, it only takes 10 s to recover the prepared materials with magnets, and the removal rate of arsenic can be as high as 75% in the first time while the removal rate reaches above 30% in the fifth time at very low concentrations of contaminants. This study revealed that the prepared Fe–Al bimetallic oxide/biochar can be used as a potential adsorbent for the removal of arsenic at low concentrations for its simple synthesis, environmental friendliness and magnetic recovery.