Cu-based perovskite as a novel CWPO catalyst for petroleum refining wastewater treatment: Performance, toxicity and mechanism.

For the first time, Cu-based perovskite oxides were used as catalysts to treat highly toxic and refractory petroleum refining wastewater based on catalytic wet peroxide oxidation (CWPO) technology. Perovskite La2CuO4 was synthesized by sol-gel method. A series of characterizations showed that the synthesized catalyst particles are tetragonal phase perovskite structure. The experimental results showed that under the conditions of catalyst dosage of 0.75 g, temperature of 100 ℃ and reaction time of 30 min, the COD removal rate was 89.58 %, the TOC removal rate was 87.38 %. The morphology and structure of the catalyst before and after the reaction proved that the catalyst has strong stability and catalytic activity. The components of raw water, Wet Air Oxidation (WAO) effluent and CWPO effluent were compared and analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), and the possible mechanism and path of WAO and CWPO degradation of petroleum refining wastewater were further explored. The changes of Cu components in La2CuO4 before and after CWPO reaction and the transformation of lattice oxygen and adsorbed oxygen were analyzed by X-ray Photoelectron Spectroscopy (XPS). The involvement of Cu (Ⅱ) /Cu (Ⅰ) in the activation of H2O2 was speculated. Finally, the biotoxicity of raw water, WAO effluent and CWPO effluent was predicted. The results provide reference value for the application of catalyst La2CuO4 in various petrochemical wastewater.