Preparation of Supported Perovskite Catalyst to Purify Membrane Concentrate of Coal Chemical Wastewater in UV-Catalytic Wet Hydrogen Peroxide Oxidation System

Abstract

The effective treatment of membrane concentrate is a major technical challenge faced by the new coal chemical industry. In this study, a supported perovskite catalyst LaCoO₃/X was prepared by a sol-impregnation two-step method. The feasibility of the supported perovskite catalyst LaCoO₃/X in the UV-catalytic wet hydrogen peroxide oxidation (UV-CWPO) system for the purification of concentrated liquid of coal chemical wastewater was investigated. The effects of catalyst support, calcination temperature, calcination time, and re-use time on catalytic performance were investigated by batch experiments. The catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). Experimental results showed that the supported perovskite catalyst LaCoO₃/CeO₂ prepared using CeO₂ as support, calcination temperature of 800 °C, and calcination time of 8 h had the best catalytic effect. The catalytic performance of the catalyst remained excellent after seven cycles. The best prepared catalyst was used in UV-CWPO of coal chemical wastewater membrane concentrate. The effects of H₂O₂ dosage, reaction temperature, reaction pressure, and catalyst dosage on UV-CWPO were determined. Under the conditions of H₂O₂ dosage of 40 mM, reaction temperature of 120 °C, reaction pressure of 0.5 MPa, catalyst dosage of 1 g/L, pH of 3, and reaction time of 60 min, the removal efficiencies of COD, TOC, and UV₂₅₄ were 89.7%, 84.6%, and 98.1%, respectively. Under the optimal operating conditions, the oxidized effluent changed from high toxicity to non-toxicity, the BOD₅/COD increased from 0.02 to 0.412, and the biodegradability of the oxidized effluent was greatly improved. The catalyst has a simple synthesis procedure, excellent catalytic performance, and great potential in the practical application of coal chemical wastewater treatment.

Keywords: UV-catalytic wet hydrogen peroxide oxidation; biodegradability; biotoxicity testing; membrane concentrate; supported perovskite catalyst.