Reducing agents enhanced prometon degradation by CuBi2O4/peroxymonosulfate: Development of interfacial electron transport and circulation of Cu+/Cu2+

Herein, hydroxylamine hydrochloride (HA) or ascorbic acid (AA) was utilized to develop the performance of CuBi2O4 activating peroxymonosulfate (PMS) for degradation prometon (PMT), which was effective for the advanced treatment of pesticide wastewater, based on which the reaction mechanism of reducing agents enhanced solid-activated PMS was discussed in the points of electron transfer and the circulation of Cu+/Cu2+. The enhanced electron transfer mechanism of promoting Cu(I)/Cu(II) cycle was confirmed firstly by electrochemical characterization and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the kinetic model results showed that the generation rate of SO4•− increase by 1.8 times and 2.9 times with the addition of AA or HA, respectively. AA was the quenching agent of •OH due to the stronger reactive with •OH and showed a lower enhancing efficiency. The transformation intermediates of PMT also supported the different derived reactive radicals, based on Density Functional Theory calculation. More importantly, the intermediates of HA and AA were also identified as the first report, based on which their application sense was sited. The work provided a novel and safe insight for improving PMS activation by solid catalysts using HA and AA.