K2FeO4 modified biochar promotes the improvement of acid soil properties and the fixation of heavy metal ions in copper mines.

Abstract

A series of environmental pollution problems will occur in the process of copper sulfide mining, especially the acidification of mineral soil. In this study, a K2FeO4-biochar (Fe-BC) system was constructed by modifying biochar. Taking copper sulfide polluted acidic soil as the research object, aiming at the problems of low pH value, excessive heavy metals and insufficient organic matter content in soil, the organic-inorganic collaborative improvement method was adopted based on soil culture experiment. Under Fe-biochar system, the composite soil amendment has excellent effect on the improvement of mine soil characteristics polluted by Pb, Cu and Zn, and the fixation ability of heavy metal ions is enhanced. Fe-BC adsorption effect on Cu2+ Due to the original biochar (BC), the adsorption capacity increased by 44.96%. The quasi-second-order kinetic model and Langmuir model fit well (R2>0.98), indicating that the adsorption of Cu2+ is mainly monolayer surface adsorption and chemical adsorption. The surface properties and pore structure of Fe-BC before and after adsorption were characterized by Scanning Electron Microscope-Energy Dispersive Spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that ferrate biochar has pore diffusion, electrostatic and complexation mechanisms on heavy metals, enhanced the solidification of heavy metals through reduction reaction.