The Solidification and Stabilization of Pb in Soil using Apatite-modified Biochar

Abstract

In this study, biochar (BC) was prepared by pyrolysis using sesame straw as the precursor, and modified with hydroxyapatite and chloroapatite to prepare hydroxyapatite-modified biochar (HBC) and chloroapatite-modified biochar (BC-Cl), respectively. The changes in functional groups before and after biochar modification were investigated using various characterization methods, and the passivation effects of BC, HBC, and BC-Cl on lead (Pb) in soil were studied. The three types of biochar were introduced into the contaminated soil at ratios of 3% and 5% to passivate the soil. After remediation, the effective Pb content in the soil decreased by 45.45%, 76.70%, and 82.38%, respectively, compared with the control (CK) group. Moreover, the effective Pb content decreased with increased of biochar dosage. When the soil was cultured for 90 d, the reducible Pb content of BC, HBC, and BC-Cl decreased by 22.03%, 22.97%, and 26.36%, respectively, while the residual state content increased by 76.22%, 88.31%, and 103.53%, respectively, compared with CK. BC, HBC, and BC-Cl effectively passivated Pb in soil, with the 5%BC-Cl soil sample exhibiting the most pronounced passivation effect. This study’s findings offer a new method for efficient utilization of sesame straw and provide a reference for developing apatite-based soil remediation materials.