Catalytic microenvironment regulation by introducing biochar into MIL-101Fe derivative for enhanced persulfate activation: Efficient antibiotic removal and RSM optimization

Persulfate-based advanced oxidization process was widely investigated in antibiotic removal. MOFs-derived carbon was potential in activating persulfate, while the inevitable sintering and agglomeration effect of catalysts during carbonization resulted in reduced performance. Low-cost biochar was a desired carrier in designing functional composites. Herein, MIL-101Fe-derived carbon/biochar composites (MCB-900) were prepared via carbonizing MIL-101Fe/corn stalk composites. Biochar supporting achieved the dispersion of MIL-101Fe derivative avoiding the agglomeration effect, but also regulated the catalytic microenvironment with more accessible active sites, high porosity, and structural defects. Accordingly, MCB-900 exhibited more efficient norfloxacin (NOF) removal (96.44 %) than biochar (32.90 %) or MIL-101Fe-derived carbon (79.49 %) via exciting PDS by the transformation of Fe species and carbonyl groups. It was found that NOF degradation was ascribed to radical and non-radical oxidization (SO4•-, O2•-, and 1O2), involving two possible degradation pathways according to LC-MS. MCB-900/PDS system exhibited high anti-interference capability for pH (2–10) and anions (Cl-, HCO3–, H2PO4-), and was suitable for actual water matrixes and various organic pollutants removal. Further, with optimization by RSM, low dosages of PDS and MCB-900 could also reach high NOF removal (>95 %). Combining emerging MOFs with traditional biochar, this work provided an effective means and reference to design high-efficiency catalysts for antibiotic removal in water treatment.