Bacteria-supported manganese oxide for enhanced fluoroquinolone antibiotics removal in peroxymonosulfate oxidation system.

The biosynthesis of bacteria-supported manganese nanoparticles is an inexpensive and environmentally friendly method for producing metal nanocatalysts, which exhibit excellent performance in peroxymonosulfate (PMS) activation and the degradation of fluoroquinolone antibiotics while alleviating ion leakage issues. Manganese oxide is synthesized in situ by bacteria. This study presents a novel approach for synthesizing bacteria-supported manganese oxide (BMOx) using the heavy metal-resistant bacterium Ralstonia pickettii. The biogenic BMOx effectively activates PMS to achieve 97.6% degradation efficiency of ciprofloxacin within 15 min under optimal conditions (pH 7.0, BMOx dosage of 0.40 g/L, and PMS dosage of 0.55 g/L). The degradation mechanism was elucidated, revealing that singlet oxygen (1O2) is the primary reactive species responsible for ciprofloxacin degradation, facilitated by mediated electron transfer from BMOx. The study identified three degradation pathways, primarily involving oxidation reactions by 1O2. Toxicity assessments indicated a significant reduction in toxicity of the degradation intermediates compared to ciprofloxacin, highlighting the environmental benefits of the BMOx/PMS system. This research underscores the potential of biogenic metal oxide catalysts in advanced oxidation processes, offering a promising solution for the remediation of antibiotic-contaminated water.