Tourmaline/ZnAL-LDH nanocomposite based photocatalytic system for efficient degradation of mixed pollutant wastewater

The photocatalytic reduction-induced activation of peroxymonosulfate (PMS) presents an eco-friendly and cost-effective approach for oxidatively degrading diverse organic pollutants in water. Nonetheless, the swift reconfiguration of photoinduced electron holes significantly hinders its overall efficiency. In this investigation, we present a novel photocatalytic persulfate activation system based on a ZnAl-LDH catalyst finely tuned by naturally polarized tourmaline (TL) minerals. The composite photocatalysts, TL/ZnAl-LDH, were employed to activate PMS for the simultaneous and efficient degradation of nitenpyram (NTP) and tetracycline hydrochloride (TC). In this system, the TL/ZnAl-LDH composite produced electrons and holes under light excitation. Subsequently, the photogenerated electrons from ZnAl-LDH on the TL surface activated PMS, leading to the formation of SO 4- •. Some of the SO 4- • further reacted with H 2 O/•OH to generate •OH. Ultimately, the NTP and TC were oxidized through the combined action of SO 4- •, •OH and photoinduced holes. Under the optimal conditions in the presence of PMS, TL/ZnAl-LDH degraded completely both NTP and TC within 45 min, with a 17 % mineralization rate. The findings indicate that the polarized electric field of TL not only promoted the separation and migration of electron-holes in ZnAl-LDH but also optimized the electronic structure of ZnAl-LDH. This optimization resulted in enhanced light absorption and improved reduction capacity. This study innovatively developed a system for activating photocatalytic PMS by incorporating naturally polarized minerals. This introduced a novel approach to sustainable and cost-effective advanced oxidation processes for water treatment.