Degradation Of PPCPs By Persulfate Activated By CuO/HNTs

Pharmaceutical and Personal Care Products?PPCPs?have been assessed by the World Health Organization as one of the most severe environmental health problems in the 21st century,and are currently hot topics in the field of environmental science research.Progestogens and antibacterial agents are endocrine disruptors with high biological activity,and trace levels can affect the growth and development of organisms.Progestogens and antibacterial agents are widely used in human life as contraceptives,disease treatments,and antibacterial active ingredients.Due to incomplete removal of traditional sewage treatment processes,a large amount of PPCPs are continuously discharged into the environment,which is harmful to human health and ecology.Therefore,the development of a fast and efficient treatment technology is imminent.In recent years,advanced oxidation techniques?AOPs?have been widely used in the research on the degradation of refractory organic substances.For the free radical pathways,the high redox potential of SO4^·-and·OH can effectively degrade most refractory organic compounds.Moreover,the nonradical pathway also plays an important role in the non-selective degradation of organics.In this study,a halloysite nanotube loaded nano-Cu O?Cu O/HNT?was prepared by a simple hydrothermal method,which could be used as a catalyst to activate persulfate?PS?to generate free radicals and nonradical pathways for the degradation of progesterone?PGT?and triclosan?TCS?,and the key influencing factors and degradation mechanism were explored.The main findings from this study are given as follows:?1?The SEM and TEM characterizations showed that the nano-Cu O was uniformly loaded on the HNTs,and formed the corn-like structures with a large specific surface area,and the functional groups on the Cu O/HNTs could supply the active sites to activate PS.?2?The results of PGT degradation by Cu O/HNTs-PS showed that,adding 0.5 g/L Cu O/HNTs and 7m M PS obtained the best degradation?100%?.The influence of different environmental factors?p H,HCO3^-and Cl^-?on the catalytic activity of Cu O/HNTs-PS system was simulated.The results showed that:due to the buffering effect of alumina in HNTs,the influence of the initial p H value and low concentration of HCO3^-and Cl^-on PGT degradation is negligible.A series of research methods such as quenching reaction,XPS,EPR and electrochemistry are used to explore the degradation mechanism.The results demonstrated that the reaction was divided into the free radical pathway(SO4^·-and·OH generation by the mutual transformation of PS,Cu?I?,Cu?II?,and Cu?III?)and the nonradical pathway?electron transfer process from the organic pollutant to the Cu O/HNTs?.In addition,the byproducts of PGT in the process were determined by LC-MS,and the possible transformation pathways were proposed.?3?The results of TCS degradation by Cu O/HNTs-PS showed that,adding 0.2 g/L Cu O/HNTs and 2 m M PS obtained the best degradation?100%?within 180 min.A series of research methods such as quenching reaction,XPS,EPR and electrochemistry are used to explore the degradation mechanism.The results showed the coexistence of free radical pathway and nonradical pathway.For the free radical pathway,the active substance is only·OH.And the nonradical pathway is the electron transfer process of TCS via PS to Cu O/HNTs.In addition,the byproducts of TCS in the process were determined by FT-ICR-MS and LC-MS,and the possible transformation pathways were proposed.Cu O/HNTs repetitive utilization experiments show that it has high stability,and TCS can be completely degraded within 240 min after 5 degradation experiments.Therefore,the Cu O/HNTs-PS system provides new resources and theoretical basis for wastewater remediation.