Efficiency and mechanism of phosphoric acid modified biochar loaded nanoscale zero-valent iron activated peroxymonosulfate for the degradation of bisphenol A

The degradation efficiency of bisphenol A (BPA) using sulfate radical-based advanced oxidation processes still requires further improvement. Herein, we prepared phosphoric acid-modified biochar-supported nZVI (PBC/nZVI) through liquid-phase reduction. Under optimized conditions, including a PBC/nZVI dosage of 1.2 g/L, pH 9.0, and PMS concentration of 2.0 mmol/L, the BPA degradation rate reached up to 92.66 % within 60 min with the mineralization rate of 45.5 %. The presence of Cl−, HCO3− and CO32− promoted the degradation of BPA, while NO3− had minimal effect. Conversely, H2PO4− and humic acid exhibited varying degrees of inhibition. The degradation of BPA involved four reactive oxygen species (•OH, SO4•−, O2•−, and 1O2), with 1O2 playing a prominent role. The pathways of •OH-induced oxidation and SO4•−-induced hydroxylation were identified as the mechanisms through which BPA was degraded. These findings highlighted the potential of PBC/nZVI as a rapid and efficient material for BPA degradation.