| Ultrafiltration(UF) is a membrane separation process which has found wide application in such fields as desalination, concentration of solution, wastewater treatment and so on, due to its low consumption, high efficiency of separation, etc.Modified polyvinyl alcohol(PVA) UF membrane was prepared by phase inversion, and a series of hydrophilic composite membranes were successfully prepared based on felt-metal, the composite membranes were used to treat o/w kerosene emulsion and metal cutting oil emulsion, and high rejection was obtained.The preparation method of composite membrane based on felt-metal was studied for the first time by hydrophilic PVA, and metal-PVA composite hydrophilic membranes were prepared by coating a certain concentration of PVA solution on felt-metal. The effects of preparation conditions, such as the coating solution concentration, sequence, times of coating, and heat-treatment, etc. on the properties of the composite membranes were studied. The results show that the hole diameter of the composite membrane decreases with the increase of the concentration of PVA, the hole diameter of composite membrane is different when the sequence of coating is different. When the higher concentration of PVA solution is used to coat the felt-metal for the first time and the other smaller one for the second time, the hole diameter of the composite membrane is relatively small, compared with that of the composite membrane made by the smaller concentration of PVA solution for the first time and the other higher one for the second time. The holes of the composite membrane contract and the stability of the membrane is improved by heat treatment. When metal-PVA composite hydrophilic membranes are used to treat the o/w emulsion with the concentration of 1000 mg L-1, the retention is 80% to 90%, and the permeate flux is from 15 L m-2 h-1 to 40L m-2 h-1 at 0.2 to 0.3MPa.The ferric sulfate modified PVA UF membranes, PVA-CA (cellulose acetate) blend UF membrane and the metal chloride modified PVA-CA blend UF membrane were prepared for the first time by phase inversion. The technologies of the preparation of a series of PVA UF membranes by phase inversion were investigated. The effects of concentration of casting solutions on the properties of membranes were investigated, and the optimum constituent was obtained. The results show that the addition of a suitable amount of ferric sulfate to the casting solution can improve the mechanic properties of the membrane and the stability in water. The permeate flux ofthe PVA-CA blend UF membrane decreases, and the rejection increases with the polymer concentration under a certain blend ratio, the permeate flux increases and the rejection decreases with CA concentration under a certain polymer concentration. The suitable composition is 8-12%PVA, 1-3%CA, 50% acetic acid(wt%), and water. The results also show that the PVA-CA blend UF membrane has better resistance to water and less swelling than those of unmodified PVAUF membrane.The effects of alkali metal chloride and alkali earth metal chloride on the properties of PVA-CA blend membrane were investigated, and the metal chloride modified PVA-CA blend UF membranes were prepared by phase inversion. The results show that the permeate flux increases and the retention decreases with the increase of salt under a certain blend ratio of PVA/CA. While the mass fraction of the salt in the casting solution is not greater than 1%, the rejection of the alkali metal salt modified PVA-CA blend UF membrane has changed little, compared with that of the unmodified PVA-CA blend membrane, but the permeate flux is much greater than that of unmodified membrane under the same operation condition. The permeate flux of BaCl2, NaCl and KC1 modified blend membranes increases 20%, 28% and 45% than that of unmodified membrane respectively, but the retention decreases only 2%, 1.5% and 1% respectively at the operation pressure of 0.30MPa. The results also show that the contact angle of the salt modified PVA-CA blend UF membrane decreases but the swel...
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