Engineered biochar modified with iron as a new adsorbent for treatment of water contaminated by selenium

Abstract

The purpose of this study was to develop an efficient method of biochar modification for effective removal of Se(VI) ions from water. Commercially available biochar produced from wheat straw was impregnated by Fe(NO3)3 (0.8, 4 and 10% w/v) and pyrolyzed at 200 °C. Optimum pH, adsorption kinetics, and Se(VI) adsorption isotherms were determined for the studied biochars. The modification significantly increased biochar’s ability for Se(VI) adsorption. The biochar modified with 10% Fe(NO3)3 has the highest adsorption effectiveness. The experimentally determined maximum adsorption capacity for the biochar modified with 10% Fe(NO3)3 was 14.3 mg g−1 for pH 5, which was the optimum pH value. X-Ray Photoelectron Spectroscopy (XPS) and Photoacoustic Fourier Transform Infrared Spectroscopy (FTIR-PAS) investigation confirmed the presence of iron oxides/hydroxides on the surface of the modified biochar. The modification also resulted in the formation of oxygen containing functional groups. The study proved that the proposed modification can be efficient in increasing the biochar effectiveness in removing Se(VI) from water.