Adsorption of Pb2+ in solution by phosphate-solubilizing microbially modified biochar loaded with Fe3O4

Industrial and agricultural development has caused serious environmental heavy metal pollution. Heavy metals are migratory, accumulative, and difficult to degrade, seriously endangering human health. Biochar is the most promising treatment for the efficient adsorption of heavy metals. A composite-modified biochar material was prepared with biochar from corn straw, modified with phosphorus-solubilizing bacteria Bacillus megaterium and Bacillus subtilis, and loaded with Fe3O4. The adsorption effect of the composite-modified biochar on Pb2+ in a solution environment was analyzed and studied. The number of adsorption sites of the modified biochar increased significantly, and the specific surface area increased four to six times. The kinetic results were consistent with the quasi-secondary kinetic and Langmuir adsorption models. The adsorption mechanism of Pb2+ is mainly based on physicochemical adsorption, which is related to adsorption on the surface of the biochar and the magnetic adsorption of the -OH, -COOH, and Fe-O functional groups after magnetic modification. The maximum adsorption capacity of BC-1 for Pb2+ reached 113.70 mg/g, which is 64.2 % higher than that of the unmodified sample.