Synergistic enhancement of Fe3+ coupling with Cu0 activated peroxodisulfate: Performance and mechanisms

Fe 2+ activated peroxodisulfate (Fe 2+ /PDS) system has been widely studied for its efficient degradation of pollutants. However, the slow circulation of Fe 3+ /Fe 2+ greatly restricted the application of the system. In the study, AOII was significantly degraded by using Fe 3+ coupled with Cu 0 activate PDS system (Fe 3+ /Cu 0 /PDS system). Compared with the traditional Fe 2+ /PDS system, the Fe 3+ /Cu 0 /PDS system greatly improved the degradation of AOII and the decolorization rate reached 80.6 % within 30 min. The quenching experiments and electron spin resonance (EPR) showed that both hydroxyl radical (•OH) and sulfate radical (SO 4 •− ) were the mainly primary reactive oxygen species in the Fe 3+ /Cu 0 /PDS system with the contribution rates of SO 4 •− and •OH being 60.54 % and 25.06 % respectively. In the Fe 3+ /Cu 0 /PDS system, Cu 0 formed Cu + through H + corrosion and PDS/O 2 oxidation . Then, Cu + oxidized by O 2 to produce H 2 O 2 and Fe 3+ was reduced by Cu 0 and Cu + to form Fe 2+ . Finally, Cu + and Fe 2+ catalyzed PDS to generate SO 4 •− , and •OH was yield by the process of Cu + and Fe 2+ induced H 2 O 2 and the reaction of OH − /H 2 O and SO 4 •− . Common water matrices such as NO 3 − and SO 4 2− had no effect on the degradation, while Cl − promoted the degradation, and CO 3 2− and fulvic acid inhibited the degradation of AOII. Over 68.5 % of AOII was degraded in the experimental water samples and the Fe 3+ /Cu 0 /PDS system had great degradation performances in practical water sample of other contaminants. Moreover, the final discharge of total dissolved copper was <1 mg/L after sediment and filtering.