Mechanism of efficient magnetic biochar for typical aqueous organic contaminant combined-adsorption removal

Magnetic biochar adsorption is one of the most promising technologies for the treatment of organic pollutants in water, but there are problems of limited adsorption capacity and adsorption rate, and the adsorption mechanism of some small molecular organic pollutants needs to be further explored. A magnetic biochar (MBC) with high adsorption capacity and adsorption rate is successfully prepared by a modified chemical co-precipitation method, and methylene blue (MB) and acetone are used as representative pollutants. Through the combination of experiments and simulations, the adsorption mechanism of magnetic biochar on typical organic pollutants is explored. The results show that the magnets loaded on MBC are composed of Fe3O4 and FeO(OH) in a ratio of about 3:2, the saturation magnetization is 11.67 emu/g, and the adsorption capacities for MB and acetone are 645.08 mg/g and 59.42 mg/g, respectively. The adsorption processes are controlled by physical/chemical adsorption and followed pseudo-second-order kinetics. The chemical adsorption process mainly includes the polar effect contributed by oxygen-containing functional groups and the π-π interaction between MB molecules and biochar. This study can provide theoretical basis and optimization reference for the removal technology of organic pollutants in water.