Preparation Of Silver Metal Organic Frameworks And Derived Carbon Materials And Their Application In Membrane Materials

The reliability and ease of operation of membrane-based water filtration systems have led to their increasing use in water and wastewater treatment.However,membrane fouling is recognized as the biggest obstacle restricting the widespread application of membrane technology.Membrane fouling will not only cause a decrease in membrane flux and retention performance,but also increase operating costs and shorten membrane service life.Hence,developing antifouling nanocomposite membrane materials has become the focus of many academic studies and industrial research.In this study,we synthesized silver complex with1,3,5-benzenetricarboxylic acid[{Ag(H₂btc)}{Ag₂(Hbtc)}]_n(Ag-MOF)and ZIF-8 derived nitrogen-containing porous carbon silver nanocomposite(NPC/Ag),the photocatalytic degradation performance,adsorption performance and antibacterial performance under visible light were investigated.Furthermore,we introduced NPC/Ag as an additive into the polyethersulfone composite membrane to prepare an anti-pollution nanocomposite membrane.The effect of NPC/Ag content on membrane structure,filtration performance and anti-biological pollution performance was systematically studied.The following results were observed:(1)The diffusion method was used to construct Ag-MOF by self-assembly of coordination and guidance.SEM and XRD results showed that the nanoparticles had good dispersibility,good crystallinity and purity,and were not doped with other impurity phases.Dye degradation experiments showed that the complex had good photocatalytic degradation performance under visible light;the main reactive species in the photocatalytic system were hydroxyl radicals(OH·)and superoxide radicals(O₂·^-).Ag-MOF had a good inhibitory effect on E.coli.(2)The nano-silver was loaded on the ZIF-8 derived nitrogen-containing porous carbon material by light deposition method.Nano-silver was evenly dispersed in the pores,without any agglomeration,and did not affect the chemical structure of NPC.NPC/Ag showed good adsorption performance for both MB and MO.With the increase of the silver loading,the adsorption capacity decreased slightly,but the lowest value could still reach 200 mg·g^-1.A series of antibacterial tests showed that the NPC/Ag nanocomposite had a good antibacterial effect on both gram-negative bacteria and gram-positive bacteria.Among them,the inhibitory effect on Pseudomonas aeruginosa was better.(3)NPC/Ag materials with different contents were introduced into PES membranes as antibacterial agents by phase inversion method.The SEM picture showed that the sample particles were evenly distributed on the surface of the membrane material,and the morphology of the membrane section had not changed significantly.All membrane samples showed similar asymmetric porous structure,including dense skin layer,finger-like porous sublayer and bottom sponge layer.The proper increase of NPC/Ag made the finger-shaped pores longer and wider,improved the connectivity of the fractured surface structure,and improved the hydrophilicity,porosity and water absorption of the membrane surface.The filtration experiment showed that the addition of an appropriate amount of NPC/Ag could effectively increase the membrane pure water flux without losing the BSA rejection rate.The NPC/Ag/PES composite membrane exhibited excellent antibacterial properties and comprehensive anti-pollution properties.NPC/Ag could be used as an effective fungicide for membrane fouling control.