Degradation of Typical Nitrogen-Heterocyclic Compounds in Coal Gasification Wastewater via Catalytic Ozonation Processes

Abstract

Reverse osmosis is a critical step in the pursuit of zero discharge for coal gasification wastewater treatment; however, the high-salt concentrates generated in this process contain refractory organic compounds, such as indole, quinoline, and pyridine, which pose significant challenges for salt recovery. In this study, catalytic ozonation using a novel Cu-Co-Mn/activated carbon catalyst was introduced to efficiently degrade these persistent organic pollutants. The optimized conditions were a pH of 9.0, a catalyst dosage of 1.3 g/L, and an ozone dosage of 1.0 g/L. Our findings reveal that the catalytic effect promotes the accumulation of hydroxyl-free radicals, which provide the necessary energy for effective degradation. The removal efficiencies of indole, quinoline, and pyridine by catalytic ozonation were remarkably high at 92.31%, 90.56%, and 80.63%, respectively. Pyridine, identified as the most resistant compound, had its electronic structure calculated using density functional theory (DFT) with Gaussian 09 software, offering new insights into the underlying degradation processes. The results demonstrate that the novel catalyst significantly boosts ozonation efficiency, offering a promising approach for treating high-salt coal gasification wastewater.