| Due to membrane separation technologys' the great advantages of high separation efficiency,easy to control,compact structure,low energy consumption and so on,it had attracted a lot of attention in the field like chemical industry,environmental protection,pharmaceutical industry.But the problem of membrane fouling obstructed its development.The membrane fouling will cause flux decline,increase the wash frequency.Finally,membrane working life became shorter.The solution is modifying of the new materials and optimizing separation process.The latter has its boundedness,but the modifying of the new materials has a broader prospect to solve this problem.CPVC membrane is easy to get preparation with favorable price,high polarity and mechanical strength,and has great performance in acid-base and microorganism resistance.PVB membrane has great tenacity.And CPVC/PVB blend membrane has both the characteristics of the CPVC and PVB,which is an new membrane material and has better performance in property.but the research about CPVC/PVB blend membranes' properties modifying and how to improve its hydrophilicity and antifouling property has not been reported.The article aims to study the way to improve the CPVC/PVB blend membrane properties.It discussed what influence of the common additives(PEG,F127)exert on the membrane properties and microstructure.Then,it studyed the dopamine coating's influence on hydrophilicity and antifouling property of CPVC/PVB blend membrane.In the research contents we can reach the following conclusions:1?PEG with different molecular weights(400,600,1000,1500,2000,4000,6000)were added into CPVC/PVB blend.A series of the experimental measurement of the blend membranes was done.The experimental results showed that the porosity had formed on the surface morphology,became dense and invisible with the increasing molecular weight of PEG.And the finger-like porous became invisible in the cross-section of membrane,the flux had improved.The hydrophilic group of PEG enhanced blend membrane in hydrophilicity and antifouling property,but decline in the mechanical property and permeability,when PEG molecular weight was 6000,the blend membrane had a better compatibility,showed obvious finger-like porous sub-layers.All in all,PEG 6000 as an additive could make CPVC/PVB blend membranes have better membrane properties.2?F127 with different mass fractions were added into CPVC/PVB blend.A series of the experimental measurement of the blend membranes was done.The experimental results showed that the surface morphology became more smooth,as F127 were added in,but didn't change the cross-sections' basic structure.And the membrane properties had declined in flux and mechanical property but greatly enhanced in hydrophilicity and antifouling property.The flux,hydrophilicity and antifouling property improved with the increasing of F127 mass fractions,but mechanical property showed the inverse pattern.All in all,when the F127's mass fractions reached 6% could make CPVC/PVB blended membrane get better membrane properties.Comparing with the PEG research and F127 research,the CPVC/PVB blended membrane with PEG6000 is more superior in flux and mechanical property,so coating the dopamine on its surface,and it will get better result.3?The results of coating the dopamine on the CPVC/PVB blend membrane surface show that: The surface morphologies and cross-section morphologies were observed by SEM,there is no porosity but dense coating in membrane surface,and the coating thickness had increased as the increasing of coating time.The dopamine did not act on the cross-section.And the membrane properties had declined in flux but enhanced in hydrophilicity and antifouling property.Mechanical property didn't change a lot.The flux climbed up and then decline as the increasing of coating time,but the membrane exhibited better properties in hydrophilicity and antifouling property as the increasing of coating time.When the dopamine coating time was at 2h,the membrane had the outstanding performance in all properties. |
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