[Preparation of MgO Modified Lotus Shell Biochar and Its Phosphorus Adsorption Characteristics]

To study the potential application characteristics of biochar as a phosphate adsorbent, nano-MgO-biochar was prepared by rapid pyrolysis of a mixture of MgO and lotus shells. The physicochemical properties were characterized by XRD, BET, SEM, and TEM, and adsorption experiments were conducted. The results showed that MgO was mainly supported on the surface of carbon in the form of flakes and granules, which increased the adsorption active site, and the adsorption amount of MgO-biochar MBC3 was 14 times higher than that of biochar MBC1 without MgO. The adsorption capacity of MBC9, which was prepared by rapid pyrolysis under 10% CO₂ atmosphere, was further increased 16 times higher than that of MBC1. The adsorption kinetics followed a pseudo-second-order model, which indicated the adsorption of phosphate on MgO-biochar was dominated by chemical adsorption. According to the Langmuir equation, the maximum adsorption capacity of MBC3 and MBC9 could reach 283.26 mg·g^-1 and 297.96 mg·g^-1, respectively. MgO-biochar is a high-efficiency phosphate adsorbent, which can be used to control the eutrophication of water.