Enhanced activation of peroxydisulfate by CuO decorated on hexagonal boron nitride for bisphenol A removal

Abstract

Abstract A series of supported catalysts consisting of CuO (2–28% w/w Cu) loaded on hexagonal boron nitride (h-BN) was fabricated via a facile impregnation-calcination method. The characteristics of the as-prepared catalysts were examined using FESEM, XRD, XPS and porosimeter indicating that the catalysts consist of microparticles morphology with BET specific surface area between 13–36 m2 g−1. Subsequently, the CuO/h-BN catalysts were used to activate peroxydisulfate (PDS) for aqueous bisphenol A (BPA) removal. Notably, the CuO/h-BN loaded with 28 ± 3% Cu (denoted as CuBN-4) had the most efficient performance with an apparent first-order rate constant (kapp) of 0.165 min−1. The PDS dosage, CuBN-4 loading, and pH highly influenced BPA degradation rate. The dominant PDS activation pathway was determined using radical scavengers indicating that the PDS activation by nonradical pathway at the Cu active sites involving surface activated complex formation contributed excessively to BPA degradation while SO4•- and HO• contribution was minor. Analysis of the LC/MS/MS results revealed the emergence of nine intermediates during BPA degradation and based on these intermediates, the BPA degradation pathways are proposed. Regardless of the pathways, the TOC results (50.2% TOC removed in 2 h) showed that BPA mineralization was eventually achieved. The CuBN-4 can be reused for multiple cycles without Cu leaching attributed to the unique property of h-BN which can also act as a Cu adsorbent. Overall, this study indicates that the CuBN-4 is stable and have promising potential to be employed as an effective PDS activator for large-scale organic pollutants removal.