Effective degradation of ofloxacin using nano-zero-valent iron activated persulfate supported by the reusable porous gel microsphere

Abstract

Ofloxacin (OFL) is a non-biodegradable novel organic pollutant in the environment. In this study, a novel reusable porous gel microsphere (RPGM) of sodium alginate-coated biochar with nano-zero-valent iron was prepared to activate persulfate (PDS) to remove OFL in water. The degradation process was fitted to the pseudo-first-order reaction kinetics, and the findings revealed that the rate of OFL removal in the RPGM/PDS system amounted to 96.91 % within 60 min utilizing 0.4 g/L RPGM and 5 mM PDS. On OFL removal, the effect of reaction conditions, including OFL concentration, RPGM dosage, initial pH, temperature, and inorganic anions was discussed. RPGM exhibited excellent stability in removing OFL, it could be recycled to activate persulfate, and the removal rate of OFL was maintained at 99.73 ∼ 78.61 % within 6 cycles. The free radical quench showed the pivotal role that SO4·− and HO· performed in the degradation of OFL. By using UPLC-QTOF-MS, the intermediate degradation products of OFL were examined, and the possible degradation pathway was proposed. Furthermore, the T.E.S.T. was used to project the toxicity of OFL and the intermediate degradation products. In summary, OFL can be degraded effectively and reproducibly using RPGM-activated PDS.