Efficiency And Application Of 1,4-Dioxane Decomposition Via Peroxymonosulfate Activation By High Permeate Flux Co₃O₄/Ti₃C₂ MXene Membrane

1,4-dioxane（C₄H₈O₂,1,4-D）is usually utilized as solvents for industrial use and chlorinated organic compounds dissolution to produce paints,cosmetics and other daily products.It has high affinity for water and strong stability.It is easy to migrate and diffuse in groundwater,surface water and other natural water bodies.Also,it is difficult to be degraded.However,it is tough to effectively remove 1,4-D from the environment by traditional physical,chemical and biological methods.Therefore,it is of great environmental significance to develop environmentally friendly,efficient and new technology for 1,4-D decomposition.In recent years,advanced oxidation process（AOPs）based on peroxymonosulfate（PMS）activation has been attracting attention due to the fact that it produces both radicals and non-radicals,accelerating ROM degradation.Scientists have found that a combination of membrane technology and AOPs（membrane/AOPs）can filter the target pollutants and produce reactive oxygen species（ROS）to degrade ROM on the membrane simultaneously.Reactive nanostructured membranes（RNM）possessing high permeability,fast mass transferring rate,and providing platforms for nanoconfinement effect,implying its feasibility in membrane/AOPs systems.The Co/Ti₃C₂ RNM was successfully prepared by spark plasma sintering process,and its characterizations revealed the heterojunction formation of Co₃O₄ and Ti₃C₂ MXene,and the XPS results showed that electrons flowed from Co₃O₄ to Ti₃C₂ MXene.The heterojunction establishment promoted the electron mobility and helped the PMS activation.Degradation experiment data showed that the permeate flux of Co/Ti₃C₂ RNM was as high as 237.8L·m^-2·h^-1 when the residence time was 3.7 s.The removal rates of 1,4-D and TOC were 85.8%and 55%driven by a low pressure（0.15 MPa）peristaltic pump.The activation efficiency of PMS was 79.4%.The residual concentration of PMS is between 0.04 m M and 0.09 m M when the initial concentration of PMS is lower than 1.0 m M.The electron paramagnetic resonance,furfuryl alcohol and methyl phenyl sulfoxide experiments results showed that^·OH,SO₄^·-,¹O₂,and high valance oxygen species（M-oxo）are the main mechanisms for efficient degradation of 1,4-D,among which ¹O₂ served as the main non-radical pathway.Density theory functional（DFT）calculations confirm the results of electron flow in XPS,and explain the reason of the superior catalytic performance of Co/Ti₃C₂ RNM through the d-band center and Fermi level.The PMS adsorption model proves the possibility of M-oxo.Stability and application experiments applied with the single pass mode of flow-through showed that Co/Ti₃C₂ RNM had strong stability,and the degradation rate of 1,4-D was still greater than 83%after 168 h operation.The actual water application experiment showed that the degradation rates of 1,4-D in landfill leachate and sulfamethoxazole and bisphenol in groundwater were 75.5-88.1%,98.2%and 100%,respectively.This study provides guidance for the practical application of RNM/PMS system.