Research On Preparation Of Modified Catalytic Ceramic Membrane And Membrane Cleaning Method Based On PMS Oxidation

Ceramic membrane filtration technology and advanced oxidation processes?AOPs?have performed a vital role in water environment governance and water resources recycling.The metal oxides-modified catalytic membrane combined with AOPs can enhance its hydrophilicity and antifouling performance.The SO4-·-based AOPs used for the cleaning process of the modified ceramics membrane has the advantage of thoroughly degrading pollutants,high efficiency,environmental protection,and high cleaning efficiency.This study prepared the ceramic membrane coated by Co₃O₄&?-Fe OOH nanoparticles and tested its filtration performance.The reversible and irreversible membrane fouling was analyzed.The fouling mechanism of the modified ceramic membrane was further revealed through the fitting analysis of the fouling model.The effect of different cleaning methods on the modified ceramic membrane fouled by humic acid?HA?was compared,and the possible mechanism of peroxymonosulfate?PMS?catalytic oxidation cleaning of the modified ceramic membrane was proposed.Co₃O₄&?-Fe OOH nanoparticles for membrane modification were prepared by ultrasonic mixing and freeze drying at first.According to the characterization results of SEM/EDS,XRD,FTIR and N₂ adsorption desorption,the prepared nanomaterials had a large specific surface area and high density of hydroxyl groups rendering its better hydrophilicity and catalytic performance.These are beneficial to membrane filtration and AOPs.Via the "covalent coupling method",the modified ceramic membrane Co Fe CM was fabricated with dip-coating followed by drying.The modification process enhanced the hydrophilicity of Co Fe CM and alleviated membrane fouling,especially hydraulic reversible fouling.The membrane fouling process of Co Fe CM was mainly dominated by cake filtration model and standard blocking model,and the membrane modification process relieved cake layer fouling.The effects of different cleaning methods on the fouled Co Fe CM by HA were compared.Among the three chemical cleaning methods?H₂SO₄,Na OH,PMS?,PMS cleaning showed the best cleaning effect.It mainly removed irreversible fouling,and the water flux recovery rate was 80%±2%.The results of physical cleaning and PMS cleaning were consistent with the results of Resistance-in-series Model analysis that the proportion of irreversible fouling was greater than that of reversible fouling.The possible mechanisms of PMS oxidation for the catalytic modified ceramic membrane cleaning was proposed,specifically including radical and non-radical oxidation mechanisms.The radical oxidation mechanisms mainly consisted of SO₄^-· and OH·.The composite of Co₃O₄ and ?-Fe OOH achieved the high-efficient regeneration of Co²⁺,and their hydroxyl groups on the surface enhanced the catalytic performance on PMS and further contributed to the degradation process of pollutants.Singlet oxygen?¹O₂?and PMS direct oxidation were the main pathways in non-radical oxidation mechanisms.