In this study, CuO/HNTs were applied to activate persulfate (PS) to firstly degrade and mineralize TCS. The morphology, crystal structure, specific surface and surface composition were characterized by SEM, TEM, BET, XRD and XPS. The experimental parameters were optimized with 0.2 g/L CuO/HNTs and 2 mM PS. TCS was totally removed in 180 min under optimized conditions. The mechanism study using the quenching reaction, EPR, XPS and electrochemistry demonstrated that even radical reactions (•OH and O 2 •- ) pathway existed; the nonradical mechanism ( 1 O 2 and surface electron transport) was dominant to the efficient TCS degradation. Using FT-ICR MS, the degradation intermediates were identified, and transformation pathways were proposed. The degradation intermediate studies indicated that TCS began to break from the aromatic ring containing monochlorine, and the Cl functional group was gradually substituted. CO 2 and H 2 O were generated with breaking of ether bonds. The toxicity of the solution was also evaluated by the survival rate of the luminescent bacteria, and the toxicity of the solution decreased overall. A stability study showed that CuO/HNTs retained good crystal structure and degradation efficiency even after 5 cycles.
Zhuofan Huang,Qintie Lin,Haoyu Luo,Pengran Guo,Qingsong Weng,Yongqian Lei,Shuailong Cheng,Shuang-Shuang Liu
Progesterone (PGT), a widely used progestogen, has become a refractory pollutant present in urban runoff. The removal of PGT in wastewater is urgent owing to its endocrine disruption. In this study, a nano-CuO loaded halloysite nanotube (CuO/HNTs) was prepared by a simple hydrothermal method, which could be used as a catalyst to activate persulfate (PS) for the degradation of PGT. The characterizations showed that the nano-CuO was uniformly loaded on the HNTs to form corn-like structures with a large specific surface area. The optimal PGT degradation efficiency (100%) was achieved with the addition of 0.5 g/L catalyst and 7 mM PS. The effects of pH, HCO 3 – and Cl - on the catalytic activity of the CuO/HNTs-PS system were investigated. The results showed that 1) pH had little effect due to the buffer effect of Al 2 O 3 in HNTs, and nearly neutral solutions were obtained after reaction even in strong acidic or alkaline conditions, 2) low concentrations of HCO 3 – and Cl - had almost no impact on PGT degradation. Furthermore, the degradation mechanism was explored by quenching reactions, XPS, EPR studies and electrochemical experiments. The results demonstrated that the reaction was divided into the free radical pathway (SO 4 •- 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 CuO/HNTs). In addition, the byproducts of PGT in the process were determined by LC-MS, and the possible transformation pathways were proposed. The CuO/HNTs-PS system might provide some new insights for the remediation of wastewaters.
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