Effective Degradation of 1,4-Dioxane by UV-Activated Persulfate: Mechanisms, Parameters and Environmental Impacts

There is more and more research focusing on the removal of dioxane by advanced oxidation technology at this stage, and this study investigated the efficacy of an advanced oxidation system with UV-activated persulfate (UV/PDS). This method had the advantages of fast reaction rate, simple equipment and convenient operation. Free radical quenching test and electron paramagnetic resonance (EPR) analysis showed that the main active radicals in the reaction system were <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>SO</mi></mrow><mrow><mn>4</mn></mrow><mrow><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> and ·OH. This study also investigated that the optimal parameters were the initial PDS dosage of 3 mM, the UV intensity of 0.190 mM/cm², the pH between 5 and 7 and the initial dioxane concentration of 50 mg/L. Additionally, after a reaction time of 150 min, the total organic carbon (TOC) content still remained at 83.53%, which revealed that the mineralization degree of organic matter was not fully achieved through UV/PDS treatment. The concentration of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>SO</mi></mrow><mrow><mn>4</mn></mrow><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> in the reaction system was 74.69 mg·L⁻¹, which complied with the standard concentration specified. Furthermore, the cytotoxicity of the system exhibited an initial increase followed by a subsequent decrease, under the influence of the intermediates. It showed that the technology could efficiently degrade organic pollutants.