Catalytic Oxidation of Phenolic Wastewater by Iron-Based Catalysts

The purpose of this study was to investigate the effectiveness and mechanism of iron-based catalysts in the treatment of phenolic wastewater by catalyzing ozone oxidation. The removal rates of phenolics and COD were systematically examined using simulation experiments with water and actual wastewater, which involved analyzing the effects of reaction time, pH, ozone dosage, catalyst dosage, and initial concentration. The phenol and COD removal rates in the simulated wastewater were 95.9% and 93.5%, respectively, respectively, while the ozone dosage was 16 mg/L/min, pH was 6.7–6.8, and catalyst dosage was 0.3 g/L. The phenol and COD removal rates in the actual wastewater were 68.6% and 68.0%, respectively. The reaction time was 30 min. The system’s efficient removal ability for phenolic compounds, polycyclic aromatic hydrocarbons, and others was confirmed through three-dimensional fluorescence and ultraviolet spectroscopy. The iron-based catalyst generates ·OH through three pathways: adsorption of activated ozone on surface active sites, continuous production of free radicals by Fe2+/Fe3+ cycling, and direct activation of ozone by Fe2+. This mechanism analysis showed that the catalyst generates ·OH. These pathways convert pollutants into small molecules or mineralized by attacking the aromatic rings and conjugated structures of pollutants. Technical references for the deep treatment of phenol-containing wastewater are provided in this study.