Degradation Kinetic and Remediation Effectiveness of 1,4-Dioxane-Contaminated Groundwater by a Sono-Activated Persulfate Process

Abstract

The well-known biorefractory organic material 1,4-Dioxane (1,4-D) is difficult to degrade in groundwater by classical treatment processes. The sono-activated persulfate process was applied to remediate 1,4-D-contaminated groundwater. The influences of the persulfate dose, solution pH, initial 1,4-D concentration, and H2O2 dose on the enhancement of 1,4-D degradation were studied. The degradation kinetic and remediation effectiveness were also investigated. Up to an 84% 1,4-D elimination was achieved with pH of 7., temperature of 25±2°C, 7.4 mmol/L persulfate, 39.2 mmol/L H2O2, 4 kHz ultrasonic frequency, 1 W of power, and 2.67 W/cm2 ultrasonic density, with an initial 1,4-D of approximately 13 mg/L after an 8-h reaction in aqueous solution. The material 1,4-D in groundwater was eliminated completely after 1 h, while the acute toxicity of the treated groundwater decreased by 99.87%. In this process, the sulfate radical (SO4•−) and hydroxyl radical (•OH) were confirmed to be primary reactive species that degraded 1,4-D. A novel reaction kinetic model grounded on the radicals’ oxidation was developed to describe the 1,4-D degradation process from the point of view of math and chemistry. The sono-activated persulfate process successfully degraded the 1,4-D present in groundwater under mild conditions and was accompanied by a toxicity reduction. In conclusion, this is a promising method to remediate 1,4-D-contaminated groundwater.