Investigation into the degradation of Acid Red 73 using a combined ozone-venturi system

The environmental pollution caused by textile dyeing wastewater has become increasingly severe. Ozone-venturi combined technology has attracted widespread attention in the field of wastewater treatment due to its high efficiency. This study systematically investigates the correlation between gas-liquid velocity and bubble size in the ozone-venturi system, and examines the effects of various factors—including gas velocity, liquid velocity, ozone dosage, initial pH, initial pollutant concentration, and reaction volume—on the degradation efficiency of Acid Red 73, aiming to validate the effectiveness of the ozone-venturi combined system in treating dyeing wastewater. Under optimized conditions, near-complete decolorization was achieved within 5 min for a 2.0 L solution of Acid Red 73 (gas velocity: 0.2 L/min, liquid velocity: 9 L/min, ozone dosage: 6.0 mg/L, initial concentration: 50 mg/L). The removal rates of COD and TOC reached 75.3% and 42.7%, respectively, after 10 min of degradation under optimal conditions. Furthermore, this study coupled ozone-venturi technology with persulfate oxidation, with the addition of 7 g of sodium persulfate, the degradation rate of Acid Red 73 was enhanced from 78.1% to 94.8% within 3 min. Possible degradation pathways of Acid Red 73 were proposed based on liquid chromatography-mass spectrometry (LC-MS) analysis and density functional theory (DFT) calculations.