Research On The Degradation Of Acetaminophen By CuMg@Fe₃O₄ Activated Permonosulfate

Advanced Oxidation Technology?AOPs?based on peroxymonosulfate?PMS?is considered to be the best choice for the degradation of refractory organic pollutants due to its ability to produce a variety of reactive species with high oxidative properties and long survival times which can effectively keep the degradation going on.But the technology of AOPs still has some disadvantages because of its high energy consumption,easy corrosion equipment and easy secondary pollution.Therefore,this study will try to use the composite material CuMg@Fe₃O₄ as a catalyst ane construct a heterogeneous advanced oxidation system PMS/CuMg@Fe₃O₄ to degrade ACE.The study will focus on the degradation efficiency,activation mechanism degradation pathway and the potential to produce some toxic by-products.The main research contents and results are as follows:?1?Two catalysts named Cu@Fe₃O₄ and CuMg@Fe₃O₄ were prepared by the method of hydrothermal synthesis.The catalytic properties of the two catalysts were compared.The morphological changes and crystallization of the two catalysts were analyzed by SEM,FT-IR and XPS.It is found that,compared with Cu@Fe₃O₄,the performance of CuMg@Fe₃O₄ which was added non-transition metal Mg metal is greatly improved,The CuMg@Fe₃O₄ has a higher crystallinity,larger specific surface area and the surface of the CuMg@Fe₃O₄ is rough with a layered structure.?2?The effects of various influencing factors and water quality parameters on the degradation efficiency of ACE in PMS/CuMg@Fe₃O₄ system were investigated.The degradation of ACE in this system is in line with the pseudo-second-kinetic model.Temperature has less effect on the PMS/CuMg@Fe₃O₄ system,because the activation energy of the reaction which is 22.14 kJ/mol is very small.The main reaction factors affecting the system are PMS concentration,catalyst dosage and pH₀.Among them,pH₀ has the most significant effect on the degradation efficiency of the system.In the range of pH₀ 6?9,the degradation rate and removal rate of ACE are better than those under extreme acid and alkali conditions.The ACE is degraded by optimized experiment and the optimum process parameters for?1 mM?were as follow:the PMS concentration is 2 mM,the catalyst dosage is 2 g/L,and the reaction temperature is 30°C.Furthermore,Studies on water quality parameters show that HCO3-and HA have a certain inhibitory effect on the degradation of ACE,while Cl-promotes the degradation of ACE.?3?The mechanism of CuMg@Fe₃O₄ activation of PMS was investigated by ionic strength experiment,quenching experiment,EPR and XPS analysis.The study found that the reaction between PMS and the catalyst in the solution is an outer spherical reaction.The active species of the reaction are mainly ¹O²,·OH,SO₄^·-,of which ¹O₂ is dominant.During the activation of PMS,CuMg@Fe₃O₄ has a valence transition between Cu???and Fe???.?4?Intermediates and final products were identified by GC-MS and a possible degradation pathway was proposed.It was found that the reactive species in the system mainly attacked the phenolic hydroxyl para-group,which formed p-diphenol and was further oxidized into small molecular organic compounds.The process includes hydroxylation,deamination,carbon-carbon double bond oxidative cleavage and single bond cleavage,etc.Besides,this study also investigative about biotoxicity and PMS residue in this system,it is show that the potential of producing toxic by-products by PMS/CuMg@Fe₃O₄ system is reduced comparing with other systems.