Insights into the synergistic role of photocatalytic activation of peroxymonosulfate by UVA-LED irradiation over CoFe2O4-rGO nanocomposite towards effective Bisphenol A degradation: Performance, mineralization, and activation mechanism

In this work, CoFe2O4-reduced graphene oxide (CFO-rGO) nanocomposite was synthesized to activate peroxymonosulfate (PMS) under UVA-LED irradiation. Bisphenol A (BPA) was selected as an emerging pollutant to evaluate the performance of the UVA-LED/CFO-rGO/PMS system. CFO-rGO was characterized by several advanced methods including XRD, FTIR, FESEM, EDX-mapping, TEM, XPS, BET-BJH, Raman spectrometry, VSM, PL, and EIS analyses. The operating factors, the determination of reactive species, and the mechanism were studied and discussed. During 30 min reaction time, more than 99% of BPA was removed by 150 mg/L PMS and 400 mg/L CFO-rGO under mild conditions (pH = 3-9). Bicarbonate ions could inhibit the BPA degradation by scavenging the free radicals. The trapping experiments exhibited that sulfate (SO4 center dot-) and hydroxyl ((OH)-O-center dot) radicals were prevailing agents for BPA degradation. Humic acid (HA) and sodium dodecyl sulfate (SDS) had a hindering effect on BPA degradation. CFO-rGO showed a high potential for recyclability up to six cycles. Moreover, the leaching of metals was approximately null for CFO-rGO, indicating that the current nanocomposite is highly stable. We also examined UVA-LED/CFO-rGO/PMS system on other pollutants, as well as real conditions. The results showed high efficiency for all conditions. The UVA-LED/CFO-rGO/PMS process could mineralize 67% of BPA during 80 min reaction time. Intermediates of BPA degradation were identified and their toxicity was also estimated. This work enlightened the ferrite catalysts' importance in activating PMS under UVA-LED irradiation for emerging pollutants wastewater remediation.