Study on improvement of copper sulfide acid soil properties and mechanism of metal ion fixation based on Fe-biochar composite
Xiao Zhang, Jinchun Xue, Huaqin Han, Yu Wang
Abstract
Abstract In this study, Fe modification of bamboo biochar (BC) with ferrate was used to construct a composite soil amendment based on K 2 FeO 4 -biochar (Fe-BC) system. Based on soil culture experiments, Fe-BC combined with organic–inorganic materials at the application levels of 3%, 5% and 10% to copper sulfide contaminated acid soil was studied. Adsorption kinetics experiment was used to investigate the adsorption capacity of Fe-modified biochar to heavy metal Cu. The results showed that the pH value of bamboo biochar could be increased by 1.12 units after K 2 FeO 4 modification. Compared with the BC, the adsorption capacity of Cu 2+ increased from 190.48 to 276.12 mg/g, which was mainly reflected in single-layer surface adsorption and chemisorption. Pore diffusion, electrostatic interaction and surface interaction are the possible mechanisms of Fe-BC interaction with Cu 2+ ions. And the contents of Pb, Cu and Zn in soil leaching state decreased by 59.20%, 65.88% and 57.88%, respectively, at the 10% application level of Fe-BC. In general, the composite modifier based on ferrate and biochar has a positive effect on improving the characteristics of acidic soil in copper mining area.