Preparation And Performance Of Catalytic Composite Membranes Containing MOF Loaded Nanoparticles

With the development of the printing and dyeing industry,the treatment of dye wastewater has become one of the urgent problems to be solved,and the simple and efficient removal of dye has become a hot topic.At present,chemical methods such as catalytic oxidation-reduction reactions and Fenton oxidation,as well as physical methods such as membrane adsorption are used in the treatment of dye wastewater.MOFs can effectively remove dyes from water by adsorption or catalysis,MOFs combined with metal and metal oxide nanoparticles can effectively enhance the catalytic performance of nano-composite particles.But granular catalysts are difficult to be separated from the reaction system,and their industrial application potential is limited.Membrane separation technology is to separate the water and pollutants in the feed liquid through the functional membrane,and the treatment process has low energy consumption and high efficiency.Therefore,the combination of membrane separation and catalytic reaction in the same processing unit has become a new research idea.In this study,different MOFs-derived particles and membrane-making processes were selected.The structure and properties of the MOFs composite membranes were optimized,and the removal ability of the composite membrane to organic dyes was explored based on the catalytic method.（1）The Ag@UiO-66-NH₂ polyamide thin-film nanocomposite（TFN）membranes were prepared by interfacial polymerization（IP）method using self-made nanoparticles Ag@UiO-66-NH₂ as catalytic additive.The effects of catalytic nanoparticles content on the morphology,permeability,anti-fouling and catalytic properties of the membrane were investigated.The results showed that the covalent bond formed by the reaction of the terminal amino group with the acyl chloride at Ag@UiO-66-NH₂ made the particle strongly anchor in the polyamide active layer.The addition of Ag@UiO-66-NH₂ not only improved the hydrophilicity and anti-pollution properties of the membrane,but also makes the TFN composite membrane have excellent degradation ability of rhodamine B（Rh B）.When the amount of Ag@UiO-66-NH₂ is 0.8 wt%,the composite membrane possessed excellent comprehensive performance,with the pure water flux was 203.7 L·m^-2·h^-1 and the flux recovery rate reached 81.6%after 7 runs.Based on oxidation-reduction reactions,the Rh B was efficiently and sustainably degraded by the composite membrane,and the removal rate of 10 mg·L^-1 Rh B solution（700 m L）reached 99.6%,and the Rh B removal rate still reached94.5%after 7 catalytic cycles.In addition,this study provided a universal method for preparing TFN membranes to effectively chimeric nanoparticles,which has great application potential in the field of catalysis.（2）The Fe₃O₄@UiO-66-NH₂/PVDF-co-CTFE mixed matrix membranes were prepared by blending method with self-made nanoparticles Fe₃O₄@UiO-66-NH₂ as catalytic additive and non-solvent induced phase separation（NIPS）method.The effects of catalytic additives content on the morphology,permeability,anti-fouling,catalytic and self-cleaning properties of the membrane were investigated.The results showed that the addition of Fe₃O₄@UiO-66-NH₂ not only improved the hydrophilicity and anti-pollution properties of the membrane but also made the mixed matrix membrane have an excellent methylene blue（MB）removal rate.When the amount of Fe₃O₄@UiO-66-NH₂ was 2 wt%,the mixed matrix membrane possessed outstanding comprehensive performance,with the pure water flux was 226.8 L·m^-2·h^-1,BSA rejection rate was 95.9%,flux recovery rate was 71.38%.Based on the Fenton reaction mechanism,the membrane had excellent catalytic performance,the removal rate of20 mg·L^-1 MB solution（400 m L）reached 99.04%,and had good self-cleaning characteristics and long-term stability.In conclusion,Fe₃O₄@UiO-66-NH₂ has dispersed evenly into the Polyvinylidene fluoride-co-chlorotrifluoroethylene（PVDF-co-CTFE）membrane substrate in this study,which provided a new idea for the long-term stable use of Fenton catalytic membrane with good antifouling performance.