Preparation And Properties Of MOFs/paes-cooh Self-supporting Hybrid Symmetric Forward Osmosis Membrane

Water shortage has recently become a significant global issue as a result of rapid population growth,rapid industrialization,and the destruction of available resources.Desalination,deep treatment,and wastewater reuse are effective ways to increase water supply without destroying natural freshwater ecosystems.Forward osmosis technology has become the most promising method to solve water scarcity and drinking water safety because of its benefits,including low energy consumption,high rate of recovery,and good separation effect.Currently,internal concentration polarization（ICP）and surface contamination of conventional thin-film composite membranes have become the main factors hindering the development and application of forward osmosis technology.Based on the characteristics of membrane contamination and ICP problems,this study combines the molecular design of membrane materials and the structural optimization of forward osmosis membranes to fabricate a new forward osmosis membrane with excellent permeation separation performance and good anti-pollution capability.The details of the study are as follows:（1）Firstly,NH₂-Ui O-66,a hydrophilic metal-organic framework material（MOFs）with specific water molecular channels（5.2?）,was synthesised by a solvothermal method.Then,through precise molecular design,the NH₂-Ui O-66 was integrated into the molecular structure of carboxyl-containing poly（aryl ether sulfone）（PAES-COOH）matrix with excellent mechanical properties,which was further combined with the structure design of the support layer free to fabricate a series of NH₂-Ui O-66/PAES-COOH self-supporting symmetric hybrid forward osmosis membrane systems.The introduction of NH₂-Ui O-66 has imparted a more hydrophilic and negatively charged membrane surface to the series of NH₂-Ui O-66/PAES-COOH forward osmosis membranes.Combined forward and reverse osmosis tests showed that the structural parameters（S）of the NH₂-Ui O-66/PAES-COOH FO membranes were nearly 0,confirming the construction of an ideal structure without ICP.Meanwhile,the appropriate content of MOFs introduced via chemical bonding interaction plays an efficient role in water molecule transport and water-salt screening during permeate separation,resulting in NH₂-Ui O-66/PAES-COOH hybrid forward osmosis membranes with significantly improved water flux and ultra-high selective permeation performance.The U₅membrane exhibited a significantly enhanced water flux of 15.04 L m^-2 h^-1 and an extraordinarily high water-salt selectivity of1740.74 L mol^-1.（2）On the basis of NH₂-Ui O-66,Ag nano particles with broad-spectrum antibacterial ability were perfused into the skeleton structure of the MOFs by photoreduction method to obtain Ag@NH₂-Ui O-66.And through the precise molecular design and the structural design of the forward osmosis membrane,the hydrophilic Ag@NH₂-Ui O-66 nanomaterial with water molecule specific channels and antibacterial capability was incorporated into the molecular structure of the PAES-COOH substrate to synthesize a series of Ag@NH₂-Ui O-66/PAES-COOH hybrid materials.Finally,the self-supporting symmetric forward osmosis membrane system without ICP was constructed by using the above hybrid materials.The strong chemical bonding between Ag@NH₂-Ui O-66 filler and PAES-COOH matrix enabled the two parts to form good interfacial compatibility,which promoted the full play of multiple functionalities of Ag@NH₂-Ui O-66.In consequence,the Ag@NH₂-Ui O-66/PAES-COOH self-supporting symmetric hybrid forward osmosis membranes exhibited excellent water permeability(13.78L m^-2 h^-1 of the optimal sample AU₅)and water-salt selectivity(1724.70 L mol^-1 of the optimal sample AU₅).In addition,the introduction of the Ag@NH₂-Ui O-66 offered a series of self-supporting symmetric hybrid FO membrane with effective antibacterial capability,as well as enhanced organic pollution resistance.The samples with the best permeate separation performance,AU₅,achieved more than 95%antibacterial rate against both E.coli and S.aureus;meanwhile,AU₅ showed a very low flux drop rate in 24 h dynamic contamination test of simulated wastewater containing bovine serum protein or sodium alginate.