Enhanced activation of peroxydisulfate by strontium modified BiFeO₃perovskite for ciprofloxacin degradation

A series of Sr-doped BiFeO₃ perovskites (Bi_1-xSr_xFeO₃, BSFO) fabricated via sol-gel method was applied as peroxydisulfate (PDS) activator for ciprofloxacin (CIP) degradation. Various technologies were used to characterize the morphology and physicochemical features of prepared BSFO samples and the results indicated that Sr was successfully inserted into the perovskites lattice. The catalytic performance of BiFeO₃ was significantly boosted by strontium doping. Specifically, Bi_0.9Sr_0.1FeO₃ (0.1BSFO) exhibited the highest catalytic performance for PDS activation to remove CIP, where 95% of CIP (10 mg/L) could be degraded with the addition of 1 g/L 0.1BSFO and 1 mmol/L PDS within 60 min. Moreover, 0.1BSFO displayed high reusability and stability with lower metal leaching. Weak acidic condition was preferred to neutral and alkaline conditions in 0.1BSFO/PDS system. The boosted catalytic performance can be interpreted as the lower oxidation state of Fe and the existence of affluent oxygen vacancies generated by Sr doping, that induced the formation of singlet oxygen (¹O₂) which was confirmed as the dominant reactive species by radical scavenging studies and electron spin resonance (ESR) tests. The catalytic oxidation mechanism related to major ¹O₂ and minor free radicals was proposed. Current study opens a new avenue to develop effective A-site modified perovskite and expands their application for PDS activation in wastewater remediation.