Well-dispersed copper and molybdenum co-doped g-C3N4 as an excellent persulfate activator for highly efficient removal of bisphenol a in wastewater

Abstract

Degradation of endocrine disrupting compounds by optimizing advanced oxidation processes is highly feasible, but remains a daunting challenge. In this work, a novel copper and molybdenum co-doped g-C3N4 (Cu/Mo@CN) were successfully synthesized via a simple dip-calcination approach, of which highly dispersed Cu and Mo atom sites were doped in the ring of g-C3N4. The Cu/Mo@CN catalysts were characterized by XRD, SEM, TEM, XPS, UV–vis DRS analyses, etc. The optimized system of Cu1/Mo3@CN catalyst in the visible light-persulfate oxidation (Vis + PS + Cu1/Mo3@CN system) had high photocatalytic activity to remove 97.2 % of bisphenol A (BPA, 5 mg/L) within 60 min. Compared to pure g-C3N4, Cu/Mo@CN has better visible-light (Vis) response function and narrower band gap (2.58 eV), which are easier to get excited by Vis illuminate. The results showed that reactive oxygen species of SO4• −, •OH and •O2− could be stably produced to contribute to the BPA degradation in Vis + PS + Cu/Mo@CN systems. Meanwhile, the Cu and Mo elements co-doped in g-C3N4 can also effectively activate PS to promote the production of reactive oxygen substances. In addition, the continuous production of photoelectrons enhanced the cycling of Cu2+/Mo6+ and Cu+/Mo4+, which could be further improved the removal efficiency of Vis + PS + Cu/Mo@CN towards BPA. The degradation mechanism of BPA were proposed according to the identification of intermediate products and DFT calculation. Overall, this study provides a viable pathway for BPA abatement in actual wastewater treatment applications.