Use of catalytic wet air oxidation (CWAO) for pretreatment of high-salinity high-organic wastewater

Catalytic wet air oxidation (CWAO) coupled desalination technology provides a possibility for the effective and economic degradation of high salinity and high organic wastewater. Chloride widely occurs in natural and wastewaters, and its high content jeopardizes the ef-ficacy of Advanced oxidation process (AOPs). Thus, a novel chlorine ion resistant catalyst B-site Ru doped LaFe1-xRuxO3-delta in CWAO treatment of chlorine ion wastewater was examined. Especially, LaFe0.85Ru0.15O3-delta was 45.5% better than that of the 6%RuO2 @TiO2 (commercial carrier) on total organic carbon (TOC) removal. Also, doped catalysts LaFe1-xRuxO3-delta showed better activity than supported catalysts RuO2 @LaFeO3 and RuO2@TiO2 with the same Ru content. Moreover, LaFe0.85Ru0.15O3-delta has novel chlorine ion resistance no matter the con-centration of Cl- and no Ru dissolves after the reaction. X-ray diffraction (XRD) refinement, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and X-ray absorption fine structure (XAFS) measurements verified the structure of LaFe0.85Ru0.15O3-delta. Kinetic data and density functional theory (DFT) proved that Fe is the site of acetic acid oxidation and adsorption of chloride ions. The existence of Fe in LaFe0.85Ru0.15O3-delta could adsorb chlorine ion (catalytic activity inhibitor), which can protect the Ru site and other ac-tive oxygen species to exert catalytic activity. This work is essential for the development of chloride-resistant catalyst in CWAO. (c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.