Ofloxacin degradation in water and porous media: Synergy effects via hydrogen peroxide activation by a micro electrolytic iron-carbon composite

Ofloxacin (OFL) may cause potential ecological risks since it cannot be effectively removed by conventional biological degradation. The advanced oxidation process is an efficient approach for antibiotic removal. Herein, a heterogeneous system for hydrogen peroxide (H 2 O 2 ) activation by nanoscale zero-valent iron (nZVI) supported on powdered activated carbon (PAC) composite (nZVI@PAC) was proposed to proceed with the removal of OFL. Typically, OFL (25 mg/L) can be removed up to 94.7 % within 60 min ([H 2 O 2 ] = 10 mM, [nZVI@PAC] = 125 mg/L, pH = 6, T = 318 K). The effects of initial OFL concentration, pH, nZVI@PAC dosage, H 2 O 2 concentration, and different actual water matrices were examined to explore the application conditions and resistance of the nZVI@PAC/H 2 O 2 system. Meanwhile, the quenching experiment, PMSO probe experiment, and EPR results showed •OH and Fe IV O were the dominant reactive species in the system. Moreover, a sensible mechanism for OFL removal was proposed that nZVI@PAC aggregates OFL on its surface by adsorption, and then persistent free radicals (PFRs) and nZVI on the PAC degrade OFL by activating H 2 O 2 to produce •OH and Fe IV O. Furthermore, the effect of micro-electronic iron-carbon composite was proved by electrochemical experiments and density functional theory (DFT) calculations. Moreover, the degradation pathway of OFL in the nZVI@PAC/H 2 O 2 system and the toxicity assessment of intermediates were also given. Meanwhile, sequential runs and continuous flow column experiments showed nZVI@PAC/H 2 O 2 system had high stability. This work provides an innovative strategy of an advanced oxidation process based on heterogeneous reactions for organic contaminants removal using metal–carbon catalysts.