Peroxymonosulfate activation by CuMn-LDH for the degradation of bisphenol A: Effect, mechanism, and pathway.

The remediation of water contaminated with bisphenol A (BPA) has gained significant attention. In this study, a hydrothermal composite activator of Cu 3 Mn-LDH containing coexisting phases of cupric nitrate (Cu(NO 3) 2) and manganous nitrate (Mn(NO 3) 2) was synthesized. Advanced oxidation processes were employed as an effective approach for BPA degradation, utilizing Cu 3 Mn-LDH as the catalyst to activate peroxymonosulfate (PMS). The synthesis of the Cu 3 Mn-LDH material was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). According to the characterization data and screening experiments, Cu 3 Mn-LDH was selected as the best experimental material. Cu 3 Mn-LDH exhibits remarkable catalytic ability with PMS, demonstrating good degradation efficiency of BPA under neutral and alkaline conditions. With a PMS dosage of 0.25 g·L−1 and Cu 3 Mn-LDH dosage of 0.10 g·L−1, 10 mg·L−1 BPA (approximately 17.5 μM) can be completely degraded within 40 min, of which the TOC removal reached 95%. The reactive oxygen species present in the reaction system were analyzed by quenching experiments and EPR. Results showed that sulfate free radicals (SO 4 •—), hydroxyl free radicals (•OH), superoxide free radicals (•O 2 —), and nonfree radical mono-oxygen were generated, while mono-oxygen played a key role in degrading BPA. Cu 3 Mn-LDH exhibits excellent reproducibility, as it can still completely degrade BPA even after four consecutive cycles. The degradation intermediates of BPA were detected by GC MS, and the possible degradation pathways were reasonably predicted. This experiment proposes a nonradical degradation mechanism for BPA and analyzes the degradation pathways. It provides a new perspective for the treatment of organic pollutants in water. [Display omitted] • With the introduction of H 2 O 2 , new two-dimensional multivalent LDHs were synthesized. • CuMn-LDH+PMS is extremely efficient and has a high degradation and mineralization capacity of BPA. • The CuMn-LDH+PMS system has a distinct bipath degradation pathway of 1O 2 and •O 2 — non-free radicals and free radicals. [ABSTRACT FROM AUTHOR]