Efficient removal of formaldehyde from wastewater by Cu defect induction of dendritic snowflake Cu7S4 Fenton-like catalysts

The discharge of colorless and water-soluble formaldehyde (FA) wastewater poses a serious threat to human health. In this study, copper based Fenton-like catalyst Cu x S y was innovatively introduced into the FA degradation system. Cu x S y catalysts with different morphologies were regulated by ethylenediamine . The Cu 7 S 4 catalyst exhibited 99% degradation performance towards FA. The physical and chemical properties of catalysts indicate that the Cu 7 S 4 catalyst has a beautiful dendritic snowflake like structure, which is more conducive to the adsorption and degradation process of FA. Electron paramagnetic resonance (EPR) detected an obvious Cu defect (g=2.064) in Cu 7 S 4 , which can effectively activate H 2 O 2 and stimulate the generation of •OH, thus accelerating the degradation of FA. Compared with Fenton reagent, Cu 7 S 4 shows more than 75% FA degradation performance (pH=5 and pH=9). Further research showed that the H 2 O 2 :Cu 7 S 4 ratio of 2:10 showed a 95% degradation effect on FA at 200–1000 ppm, demonstrating a more efficient and stable FA degradation ability. Moreover, the mechanism of FA degradation was analyzed.