| Membrane separation technology has been applied in many fields due to its lowenergy consumption, high separation efficiency and simple operation process.However, the presence of membrane fouling obstructs its promotion and application.Major method to solve this problem is developing new membrane materials. ThePVC/SPES blending membranes with the advantages of good hydrophilicity, strongmechanical performance, low price and good performance of anti-pollution wereprepared, while the microscopic structure of the blend membranes still need to controland optimization. Therefore, this issue by changing the membrane formationconditions (casting solution polymer content of casting solution temperature,coagulation bath temperature and composition of coagulation bath) and the additionof organic additives (series of organic polymer PEG, PVP, F127) and inorganicadditives (nano-SiO2and graft modified PVP-g-SiO2) on the microscopic structure ofthe membrane could be controlled and optimized to get the best conditions and thebest membrane of additives and dosage.The following conclusions were got from this study:1. Under different membrane formation conditions (polymer content, castingsolution temperature, coagulation bath temperature and composition) to observe thepreparation of PVC/SPES blend membrane sectional microstructure and surfacemicrostructure. Then, the tests of water flux, retention, tensile strength and resistanceof pollution performance indicats that the polymer content of16%casting solutiontemperature of70℃, coagulation bath temperature is20℃, bath gel pure water, themicrostructure and properties of PVC/SPES was the best.2. Organic additive (PEG, PVP and F127) affected the results of themicrostructure and properties of blend membranes, showing as followed: Three kindsof additives made the section of the finger holes were significantly larger, while PEGand PVP membrane skin thick dense membrane with PEG, the distribution of poreswere not uniform, and added PVP membrane sectional structure of the membrane than the rule; F127additives sectional structure of the membrane rules, thin and densemembrane surface. The results of water flux, rejection ratio and the performance ofanti-fouling resistance indicated that: PEG and PVP accession of the blend membranewater flux decreased to increase the retention rate, fouling resistance decreasedslightly, while the F127will make a total of mixed membrane water flux, retention,stain resistance properties are greatly improved. So F127is regulated PVC/SPESblend membrane is preferably an organic additive microstructure and properties.Additives also affected the results of the percentage of the structure and properties ofthe membrane showed that: the best percentage of F127is5%.3. Inorganic additives (nano-SiO2and grafting modified PVP-g-SiO2) impactedthe microstructure and properties of blend membranes, showing as followed:nano-SiO2membrane was added gradually to make the blend finger hole sectionalstructure significantly turn to be large, the support layer gradually becoming loose, themembrane surface density level changing a little; and PVP-g-SiO2membrane wasincreased gradually blend section so finger hole diameter smaller than the nano-SiO2membrane surface was more smooth and compact surface. The results of water flux,rejection ratio and the performances of anti-fouling resistance indicated that:nano-SiO2was increased gradually to make the pure water flux blend membranegradually increased interception rate remained at above95%, fouling resistancechanged little; the additive PVP-g-SiO2membrane is added gradually to make theblend first increased then decreased water flux, rejection and water flux was just theopposite, little change after fouling resistance decreases firstly. Thus, nano-SiO2wasbetter than PVP-g-SiO2in the microstructure and performance regulation PVC/SPESblend membrane. Additives also affected the results of the percentage of the structureand properties of the membrane showed that: the best percentage of nano-SiO2is8%. |
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