Fe2P/biocarbon composite derived from a phosphorus-containing biomass for levofloxacin removal through peroxymonosulfate activation

Abstract

Phosphorus-containing biomass represents one kind of sustainable and environmental-benign precursor for transition metal phosphide synthesis. Herein, we adopt abundant agricultural biomass of rice bran as both P and C precursor to fabricate iron phosphide/biocarbon composite. Through a ball-milling pretreatment coupled with a molten salt-assisted pyrolysis process, Fe2P/biocarbon composite (Fe2P/BC) with high specific surface area is obtained. The as-synthesized composite could be applied as environmental material for model antibiotic pollutant (levofloxacin, LEV) removal from aqueous solution through adsorption and peroxymonosulfate (PMS) activation. Under the typical reaction conditions of 0.25 g L−1 Fe2P/BC, 0.1 g L−1 PMS, pH 7 and room temperature, 96.60% of LEV (initial concentration 10 mg L−1) could be removed within 60 min. Through quenching experiments and electron paramagnetic resonance (EPR) tests, active species including SO4−•, •OH and 1O2 are found responsible for LEV degradation. Various reaction intermediates are detected by gas chromatography-mass spectrometry (GC–MS) and liquid chromatography-mass spectrometry (LC-MS), which enable us to propose the rational degradation pathways of LEV. Although the mineralization efficiency only reaches 39.02%, LEV degradation solution does show remarkably weakened antibacterial activity against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 compared with original LEV, indicating the possible low ecotoxicity of the developed Fe2P/BC-PMS system for environmental remediation.