Improving peroxymonosulfate activation by copper ion-saturated adsorbent-based single atom catalysts for the degradation of organic contaminants: electron-transfer mechanism and the key role of Cu single atoms

Abstract

Nonradical pathway-based persulfate oxidation technology is considered to be a promising method for high-salinity organic wastewater treatment. However, tremendous controversies still exist in the occurrence and mechanism of the nonradical pathway, impeding the development of this oxidation technology for wastewater treatment practice. For this consideration, atomic Cu anchored on waste adsorbent-based biochar (SACu@NBC) was fabricated as a cost-effective catalyst for peroxymonosulfate (PMS) activation to decompose high concentrations of bisphenol A (BPA). BPA removal was not suppressed by common radical scavengers, indicating the absence of radicals. The involvement of ¹O₂ was excluded by a series of experiments, including quenching tests and scavenger degradation tests. Ultimately, the electron transfer pathway was determined to be the dominant mechanism in the SACu@NBC/PMS system via the anodizing analogy method that combined the quantitative structure–activity relationship. Furthermore, dynamic fitting coupled with density functional theory (DFT) calculations illuminated that the isolated atomic Cu in carbon supports served as the active sites, which narrowed the band gap and improved the electron transfer capacity. The catalyst-oxidation performance of SACu@NBC/PMS was successfully demonstrated in an ultrafiltration device, suggesting the promise of the electron transfer pathway in the SACu@NBC/PMS system for high-salinity wastewater treatment.