Copper-based Ruddlesden-Popper perovskite oxides activated hydrogen peroxide for coal pyrolysis wastewater (CPW) degradation: Performance and mechanism.

Coal pyrolysis wastewater (CPW) contained all kinds of toxic and harmful components, which would seriously threaten the natural environment and human health. However, the traditional advanced oxidation processes frequently failed to remove phenolic substances. An A2BO4-type perovskite (La2CuO4) was successfully synthesized through sol-gel process and first applied in the treatment of CPW. More than 90% of 3, 5-dimethylphenol (DMP) was removed within 200 min at neutral conditions. Moreover, La2CuO4 also displayed excellent catalytic activity and stability in the actual CPW treatment process. Results demonstrated that DMP was removed through the attack of ∙OH, ∙O2- and 1O2 in La2CuO4/H2O2 system. The La2CuO4 were more favorable for H2O2 activation and have a lower adsorption energy than LaFeO3. XPS of fresh and spent La2CuO4 illustrated that the decomposition of hydrogen peroxide (H2O2) was mainly due to the redox cycle between surface copper and oxygen species. Moreover, the possible degradation pathway of DMP was deduced by identifying degradation products and analyzing density functional theory (DFT) calculations. This research provided a novel strategy for the development of perovskite-based catalytic materials on the treatment of practical CPW.