Peroxydisulfate Activation by Biochar from Banana Peel Promoted with Copper Phosphide for Bisphenol S Degradation in Aqueous Media

In this work, the decomposition of bisphenol S (BPS) by biochar derived from banana peel (BPB) promoted by copper phosphide (Cu3P) was examined. Different materials with Cu3P loadings from 0.25 to 4.00 wt.% on biochar were synthesized, characterized using the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and evaluated. Nearly all of the synthesized materials exhibited low to moderate adsorption capacity, attributable to their limited surface area (<3.1 m2/g). However, in the presence of sodium persulfate (SPS), the 2%Cu3P/ΒPB/SPS system was capable of removing 90% of 500 μg/L BPS in less than 10 min. The system’s performance was enhanced under inherent pH, and the reaction rate followed pseudo-first-order kinetics with respect to BPS and persulfate concentrations. Interestingly, the presence of 250 mg/L of sodium chloride had a negligible effect, while low to moderate inhibition was observed in the presence of bicarbonates and humic acid. In contrast, significant retardation was observed in experiments performed in real matrices, such as secondary effluent (WW) and bottled water (BW). According to scavenging experiments, both radical and non-radical mechanisms participated in the BPS degradation. Four transformation products were identified using the UHPLC/TOF-MS system in negative ionization mode, with two of them having higher molecular weights than BPS, while the other two TBPs involved the ring-opening reaction, and a BPS decomposition pathway was proposed.