Study On Supported Brownmillerite Copper-doped Strontium Cobaltate/polysulfone Catalytic Separation Membrane

Ultrafiltration membrane separation technology is widely used in the field of water purification due to its advantages such as no phase change,low energy consumption,easy operation and small footprint.However,due to the lack of chemical reaction process,the application range and antifouling capacity of ultrafiltration membranes are limited,which is one of the problems that urgently needs to be solved in the practical application of ultrafiltration membranes.In this paper,a series of supported brownmillerite copper-doped strontium cobaltate(Sr Cu_xCo_1-xO_3-λ/MCM-41,SCCM)composite catalysts were prepared for the activation of peroxymonosulfate（PMS）to degrade organic compounds.Then,the optimized catalyst was incorporated into polysulfone（PSf）ultrafiltration membranes.The performance of the resultant PSf/SCCM catalytic separation membrane was investigated and a mechanism of purifying organic wastewater by this membrane was proposed.First,the brownmillerite Sr Co O_2.5 rich in oxygen vacancies and containing highly active transition metal Co was selected as the catalyst for activating PMS to degrade rhodamine B（Rh B）.In order to increase the content of oxygen vacancy of the catalyst and accelerate the Co²⁺/Co³⁺redox cycle,the Sr Cu_xCo_1-xO_3-λ（λ≥0.5）catalysts with Cu doping were prepared by sol-gel method.It was found that the partial substitution of Cu for Co improved the catalytic activity of the catalyst.When the doping amount of Cu was 30 mol%,the catalyst SCC37 had the highest catalytic activity.Then,in order to reduce the agglomeration of the catalyst and improve the catalytic activity of the catalyst,this study further used the incipient wetness impregnation method to load the catalyst onto the mesoporous molecular sieve MCM-41 to prepare the SCC37/MCM-41 composite catalyst.It was found that loading the catalyst SCC37 on MCM-41 could effectively improve the dispersibility of SCC37 and reduce its size.When the catalyst loading was 40 wt.%,the composite catalyst SCCM-40%had the highest catalytic activity.Next,the composite catalyst SCCM-40%was introduced into the PSf ultrafiltration membrane by non-solvent induced phase separation method.The catalytic oxidation and antifouling properties of the resultant PSf/SCCM catalytic separation membrane were investigated.It was found that PSf/SCCM catalytic separation membranes had favorable capacity for activating PMS to degrade Rh B.In the presence of 2.5 mmol·L^-1 PMS,PSf/SCCM catalytic separation membranes could completely degrade 20 mg·L^-1 of Rh B in 12 min.In the case of an initial p H of 5?9 and the presence of humic acid,the PSf/SCCM catalytic separation membrane still had good Rh B degradation capacity,and its catalytic oxidation performance did not decrease significantly after five consecutive cyclic operations.After the PMS-based cleaning process,the flux recovery rate of PSf/SCCM catalytic separation membrane（84%）was higher than that of the PSf membrane（45%）,implying a better antifouling performance of the PSf/SCCM catalytic separation membrane.Finally,quenching experiments were conducted to identify the types of radicals in the PSf/SCCM/PMS reaction system.The results show that SO₄^·—,·OH and ¹O₂ were all present in the PSf/SCCM/PMS reaction system,and SO₄^·—and ¹O₂ were main radicals that accounted for the organic degradation.The research results show that the composite catalyst SCCM-40%can efficiently activate PMS to degrade organic matter,and it has good application prospects in endowing the ultrafiltration membrane with catalytic oxidation performance and improving antifouling capacity of the ultrafiltration membrane.