Exploiting an outdoor Pickering plate reactor for photocatalytic wastewater purification and high-value chemicals recovery under sunlight

Wastewater purification and resource recovery present significant challenges for environmental sustainability. Herein, a self-designed plate reactor based on Pickering emulsion (PE) was reported for efficiently treating and recycling wastewater under sunlight irradiation. In this reactor, PE was formed using amphiphilic TiO 2 modified with organic pollutants, resulting in a photocatalytic degradation rate with 2.2 times higher than that of traditional powder system under sunlight, and the mineralization rate reached to 99.8 % within 24 h. This accelerated mineralization is attributed to the unique spatial separation of oleophilic intermediates through the oil–water interface of PE, which also enables the recovery of high-value chemicals. Notably, due to the dynamic re-modification of TiO 2 surface by degradation intermediates, the Pickering microcapsules remained stable during the degradation process, and deformed to varying degrees in the final stage of mineralization. It is suggested that the morphological changes of Pickering microcapsules can reflect the real-time mineralization rate and can serve as a visual indicator of the micro-degradation reactions. This work reveals the formation and stabilization mechanism of PE, facilitating the real application of Pickering plate reactor for efficient sunlight-driven photocatalytic wastewater purification and resource recovery.