Research On The Pollution Control Of Ultrafiltration Membrane In The Water Purification Process By Metal Oxide Catalyzed Persulfate

The ultrafiltration process plays an important role in the treatment of drinking water,and the membrane fouling problems encountered during the use of ultrafiltration membranes have inhibited its further development.The mitigation of membrane fouling has also become a research hotspot of researchers in the field of membrane technology.Oxidative pretreatment technology is an effective method to effectively alleviate membrane fouling.In this study,three nano metal oxides（CuO,MnO₂,and Co₃O₄）were used to activate potassium persulfate（MeOx/PMS,peroxymonosulfate）system,and the effects of three MeOx/PMS systems on oxidative pretreatment of actual water bodies and their effects The influence of ultrafiltration membrane fouling control,and discussed its mechanism of action.The experiment first selected natural surface water Yingxue Lake water as the target water body,and selected humic acid,bovine serum protein and sodium alginate as the main membrane fouling components in natural organic matter,using organic indicators(DOC and UV₂₅₄),three-dimensional fluorescence Spectral and molecular weight distribution,the effect of each MeOx/PMS system on the removal of actual water and three membrane foulings was investigated.The results show that each MeOx/PMS system reduces the DOC and UV₂₅₄ of the raw water to varying degrees.Among them,the Co₃O₄/PMS system has the best treatment effect,which reduces the DOC of natural surface water,humic acid,sodium alginate and bovine serum protein by 41.84%,47.98%,35.91%and 81.51%,respectively,and makes the natural surface water and rot The UV₂₅₄ of genotropic acid is reduced by 54.54%and 88.51%,which is significantly better than other MeOx/PMS systems.Through three-dimensional fluorescence spectroscopy analysis,it was found that the MeOx/PMS system can significantly reduce the fluorescence intensity of proteinaceous substances and humus substances in raw water,and further found that proteinaceous substances will be preferentially removed by parallel factor analysis.The experiment also selected four kinds of dyes as representatives of trace foulings,and studied the removal efficiency of MeOx/PMS system for trace organic substances in water.The results show that MeOx/PMS system can significantly reduce trace organic components in water.Subsequently,the experiment explored the control effect of each MeOx/PMS system on membrane fouling caused by natural surface water and three membrane fouling components.The results show that the various systems alleviate the reversible and irreversible fouling caused by natural surface water to varying degrees.Among them,the Co₃O₄/PMS system has the best mitigation effect,and the removal rates of reversible and irreversible fouling are 81.60%and53.73%,respectively.The genotropic acid and Co₃O₄/PMS system have a good mitigating effect on the reversible and irreversible fouling caused by them.The removal rates are 81.98%and39.57%,respectively,while the CuO/PMS and MnO₂/PMS systems only have some effects on the reversible pollution caused by them.A certain control effect,the removal rate is 17.51%and45.97%respectively;for bovine serum albumin,CuO/PMS and Co₃O₄/PMS systems can effectively control the membrane pollution caused by CuO/PMS and Co₃O₄/PMS systems.The removal rates of reversible fouling were 90.29%and 98.44%,respectively,and the removal rates of irreversible fouling caused by them were 75.64%and 90.03%,respectively.However,the oxidation ability of MnO₂/PMS is weak,and it cannot fully oxidize proteins,or even increase it to a certain extent.Membrane fouling;the type of membrane fouling caused by sodium alginate is almost all reversible fouling（accounting for 97%of the total resistance）,and each MeOx/PMS system has effectively alleviated the reversible fouling caused by it.Reduced 90.65%-99.65%.Then,the experiment further confirmed by scanning electron microscopy and Fourier infrared spectroscopy that the MeOx/PMS system achieved the purpose of controlling membrane fouling by oxidizing organic foulings.Based on the above research,the effect of each system on membrane fouling control is:Co₃O₄/PMS>CuO/PMS>MnO₂/PMS.The Co₃O₄/PMS system has a good control effect on the actual water body and the membrane fouling caused by the three membrane fouling components.Finally,the experiment investigated the difference in catalytic decomposition efficiency of the three MeOx activated PMS,and found that PMS decreased by 42.15%,65.24%,and 99.41%under the activation of CuO,MnO₂,and Co₃O₄,respectively.The ability ranking is:Co₃O₄>CuO>MnO₂.The study also found through the electron paramagnetic resonance spectroscopy and free radical inhibitor test that the oxidation active species produced by the MeOx/PMS system are mainly^·OH and SO₄^·-,of which SO₄^·-degrades organic matter more efficiently.In order to further explore the MeOx/PMS system’s process of membrane fouling control,the experiment used the"membrane pore blockage-filter cake layer filtration"model to fit and analyze the ultrafiltration data of raw water,and found that the model can accurately simulate the ultrafiltration of raw water During the process,the fouling mechanism in the early stage was clogging of the membrane pores,and in the later stage,the fouling mechanism gradually changed to filter cake layer filtration.After the raw water was pretreated with MnO₂/PMS,CuO/PMS and Co₃O₄/PMS,the filtration volume required for the transformation of the fouling mechanism was increased from 60 mL to 80,110 and 120 mL.The formation of the layer extends the filtration time of the membrane.This paper systematically studied the control effect of MeOx（CuO,Co₃O₄ and MnO₂）activated PMS oxidation on the ultrafiltration membrane fouling caused by natural organic matter,and explored the mechanism of metal oxide activation of PMS.The results suggest that MeOx/PMS oxidation has the potential for membrane fouling control in practical applications.