Study on the performance and mechanism of maghemite modified biochar towards periodate activation

The activation of periodate (PI) by biochar is a promising process for antibiotic wastewater purification, but its activation efficiency for PI needs to be improved. This work successfully prepared maghemite modified Eichhornia crassipes biochar (MEBC) through a simple impregnation pyrolysis process, which enhanced the PI activation performance of biochar while reducing the aggregation of maghemite active sites. The degradation efficiency of tetracycline (TC) by MEBC increased by 43.92% compared to the original biochar, and the degradation rate constant k_obs was 4.74 times that of the original biochar. MEBC exhibits effective degradation of TC within a wide pH range of 3 − 11, and is less affected by Cl⁻, NO₃⁻, SO₄²⁻, and HCO₃⁻ ions. Except for TC, MEBC showed removal effects on norfloxacin, carbamazepine, and atrazine through PI activation. Mechanism analysis revealed that •OH, IO₃•, and ¹O₂ are the active species responsible for TC degradation in the system, mainly produced by active Fe²⁺ on the surface of MEBC, while surface C-OH and C = O groups play secondary roles. This work provides an efficient catalyst for PI activation.