A novel layered porous Fe, Cu dual-loading biochar heterogeneous catalyst to guided non-free radical pathway for peroxymonosulfate activation

Engineering active sites on catalyst surface to enhance selective oxidation pathways in advanced oxidation processes (AOPs) is key to the efficient removal of pollutants. In this work, a method of loading bimetallic ions and simultaneously activating the surface of swine manure biochar using cetyltrimethylammonium bromide (CTAB) was developed. By applying SiO2 templating method to increase the surface area and pore size of the catalyst, this study prepared a copper-iron-loaded layered porous catalyst (CFBC-0.5/1) with abundant active centers was successfully prepared. Characterisation results demonstrated that the distinctive layered porous structure enhanced the defect degree and carbonyl group (C--O) content of the biochar, thereby exposing a greater number of metal active sites. The exchange effect of Cu-Fe accelerated the activation rate of the peroxymonosulfate (PMS), which facilitated the generation of more active species. Furthermore, CFBC-0.5/1 demonstrated exceptional efficiency, achieving over 90 % tetracycline (TC) removal even under challenging conditions involving varying pH levels and competing ions. This renders it a promising catalyst for practical applications. Quenching experiments and electron paramagnetic resonance (EPR) tests revealed that singlet oxygen (1O2) was the primary active species. Additionally, electrochemical experiments demonstrated that the electron transfer between the modified bimetallic-loaded catalyst and PMS was significantly enhanced, which promoted the activation of PMS during the degradation process. It was found that the electron transfer and 1O2dominated non-radical pathway occupied the whole degradation process. This work provides significant insights for the development of efficient biochar catalysts and the targeted activation of non-radical pathways in AOPs.