Preparation Of Mil-53(Al)/Aromatic Polyamide Hybrid Membranes And The Performance Study

Metal-organic frameworks(MOFs) has been studied extensively owing to their exceptionally high surface area, controlled porosity,tunable chemical composition and the organic linkers present in their structure facilitates a better affinity for polymer matrix, which considered to be rational fillers in hybrid membranes. In this paper, aromatic polyamides and MIL-53(Al), a subfamily of MOFs, were used as polymer matrix and filler, respectively. The asymmetric membranes were prepared by non-solvent induced phase separation. On this basis, the hybrid membranes were characterized by the permeability, the potential application in organic nanofiltrtion and desalination of dyes were also investigated.First, the pure flat nanofiltration was prepared by means of phase inversion method, with aromatic polyamid(polyisophthaloyl metaphenylene diamin) as membrane material, dimethylacetamide(DMAc) as solvent and lithium chloride(LiCl) as an inorganic salt additive. The effects of polymer solution in casting solution and the casting conditions such as the temperature and the evaporation time ofnascent membrane on the performance of membrane were discussed to get the optimum membrane preparation conditions. The performance of fabricated membrane was evaluated by salt solution and small organics solution.Then blend of aromatic polyamid solution and different mounts of MOFs to prepare a series of hybrid nanofiltrtion memranes. The membranes were characterized by Fourier infrared spectroscopy(FTIR),X ray photoelectron spectroscopy(XPS), X-ray diffraction(XRD),scanning electron microscopy(SEM) and static contact angle, the results showed that the membrane microstructure was changed and the membrane surface hydrophilicity was improved. In separation experiments, pure water flux of the hybrid membranes increased while the retention maintained. The chemical stability of membrane in organic solvent was valued by swelling degree in methanol, ethyl acetate and toluene, the result indicated that the embedded MOFs suppressed the adsorption of solvent, and thus alleviated membrane stability. The results of water flux and of the rejection of nitroso R salt(NRS) in aqueous solution after exposure of the membranes to three different organic solvents(methanol, ethyl acetate and toluene) showed that the pure flux decreased 21.31-41.13%, while the rejection increased slightly. The membrane stability in ethanol was analyzed as well; the constant flux indicates that the membranes can be used. In addition, the newly preparedmembranes for potential application in organic solvent nanofiltration were evaluated on the basis of the permeances and rejection of brilliant blue G in ethanol, and the performance and rejection was 7.0 L/m2 h and94.00 %, repectively.Finally the hybrid membrane prepared in this experiment was applied for dye desalination. The effects of operation pressure, salt concentration and dye concentration on dye purification were studied.Also we conducted the anti-fouling performance test. The newly prepared hybrid membranes have an acceptable performance in dye separation application.