| Forward osmosis is a novella-burgeoning membrane separation process which attracts more and more people’s attention in recent years. Given the fact that the technique undergoes unremitting innovation and development, the performance of FO membrane are appealed to reach higher and higher level. Benefiting from its fine performance, high water flux and other advantages, the composite FO membrane has succeeded in triggering researchers’interests. Taking into consideration the deficiencies of composite FO membrane, such as low water flux, poor chlorine resistance and so on, this paper is designed to develop a new type of composite FO membrane and further explore manufacture conditions, influencing factors, stream coefficient and its anti-chlorine, anti-fouling. The composite FO membranes were prepared by interfacial polymerization with polysulfone taken as porous support membrane and m-XDA and TMC respectively adopted as aqueous phase and oil phase; Besides, some influences on film-forming property, including volatilization time, polysulfone concentration, addictive concentration, bath temperature, BPO concentration, polymerization time, heat treatment temperature and others are investigated. Under the optimal experiment conditions, the composite FO membrane are operated, and its anti-chlorine, anti-foulingwere probed by rudimentary performance test.Through changing the parameters of polysulfone concentration, addictive concentration, bath temperature and other elements, the experiment aims to manufacture different types of porous support membrane, and explore their effects on the property of composite FO membrane. The result shows that for those composite FO membranes manufactured under the same circumstance, with the rise of polysulfone concentration, their water flux tend to decline; In addition, the rejection rate initially increases before declines. With the increase of addictive in casting solution, the water flux is inclined to reduce, whereas there is only marginal difference in terms of rejection rates which are all above 90%. When the TMC concentration is bound, other conditions remain the same and solely the m-XDA concentration is varied from 0.5% to 1.5%, the water flux is found to decline with the increase of m-XDA, whereas no obvious variation in rejection rates which are all above 90%. The above phenomena may be attributed to the hypothesis that when the m-XDA concentration is low, the formed composite layer is rather thin, which impedes the salt’s removal effectiveness yet facilitate the flux. On the contrary, when the m-XDA concentration is high, the flux is weakened because of the overly thick and not well-distributed separation layer and other factors. The influence of environment humidity on polysulfone support membrane’s property is not distinct and the variation on humidity causes no big difference. Volatilization time throws certain effect on fenestra, so does the bath temperature on the structure of the support membrane fenestra for which the water flux of composite FO membrane firstly increases and then declines with the rise of bath temperature. Finally, the optimal condition of interfacial polymerization was:support membrane:16% PSf+77% DMAc+10% PVP+0.6% H2O+0.4% SDS; composite membrane:m-XDA is 0.5%(w/w), TMC is 0.05%(w/v),60s volatile time,40℃ water bath, humidity is 70%rh-80%rh,20℃ temperature,120s polymerization reaction time, 100℃ heat treatment temperature. The composite FO membrane processed according to this scheme exhibits optimal performance.The test conditions in the FO process including the membrane orientation, different draw solutions has been studied, which can affect the performance of the FO membranes through putting effect on the internal concentrated polarization(ICP). By the way, comparison the MPD composite FO membrane and the m-XDA composite FO membrane. The experimental data demonstrate that when the membrane’s separation layer face to feed solution, (namely FO pattern), the membrane’s water flux is low as well as its salt flux; when the membrane’s separation layer face to draw solution, (namely PRO pattern), the membrane’s water flux is high as well as its salt flux; use the same concentration of sodium chloride, magnesium chloride, sodium sulfate, magnesium sulfide as draw solution, other testing conditions kept invariant, the testing results show that with the decrease of pressure difference for the membrane’s two sides, the water flux also reduces; with increasing ionic radius, the water flux decreased, reverse salt flux decreases.A result is reached after putting the manufactured composite FO membrane into chlorine resistance and resistance to fouling researches that when the available chlorine’ handling capacity of composite FO membrane is below 2000ppmh, its rejection rate presents slight decrease, while the water flux performs trivial increase. When above 2000ppmh, obvious decline occurs to rejection rate and sharp rise to water flux. In consequence, the chlorine resistance capacity of the manufactured composite FO membrane can stay at 2000ppmh. Via the experimental comparison of membrane pollution, it is found that in the HA simulated solution, the water flux of composite FO membrane is declining. After a further contrast of pH=5.5 and pH=8.0, a fact is confirmed that lower pH value accompanies with more serious pollution and lower water flux. As a result, pH value acts as an important index in influencing membrane pollution. |
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