可控微球的制备及其在多孔滤膜截留机制研究中的应用

发布时间：2018-06-10 15:07

本文选题：微球 + 粒径可控　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：多孔滤膜广泛应用于水处理领域,其对杂质具有良好的截留能力,其截留机制研究对于膜处理技术具有重要的理论指导意义。已有的报道普遍通过扫描电镜(SEM)观察聚苯乙烯、纳米金或红血球等微球过滤后的滤膜特征来研究截留机制,其缺点是微球物化特性(粒径、荷电性)可控性差、成本高、测试过程复杂。本研究制备得到了一种粒径可控、表面电位可调的微球,并利用微球初步研究了多孔滤膜的截留机制。采用聚砜(PSF)、聚苯乙烯(PS)母液建立了一种粒径可控的亚微米级、纳米级微球制备方法。通过考察制备条件对微球粒径分布的影响发现:对于PSF母液体系,粒径分布主要取决于母液浓度(0.05%wt~1.0%wt)及凝固剂组成(NaCl/超纯水),PS母液体系主要取决于母液投加量(100μL~1 000μL)及有机溶剂种类(N,N-二甲基甲酰胺和N,N-二甲基乙酰胺);提高凝固剂中乙醇含量微球粒径变小,提高NaCl盐含量则粒径变大,十二烷基硫酸钠(SDS)含量对微球的粒径变化无明显影响。改变微球溶胶中共存离子(SDS和MgCl2)浓度实现了对微球表面电位的调控。通过改变SDS浓度发现:提高SDS浓度(0.017 mmol/L~1.01 mmol/L)电位增大(-3.22 mV~-61.77 mV),有利于微球维持稳定。不同SDS浓度条件下,MgCl2浓度变化对微球表面电位的调控结果一致。实验结果表明:改变MgCl2浓度,低浓度时(0.02 mol/L),Mg2+大幅降低Zeta电位(-61.77 mV至-4.33 mV)但胶体稳定性不变,因为微球表面会吸附SDS而构建一道水化膜,水化膜对胶体稳定性具有决定性作用;中浓度时(0.02 mol/L~0.1 mol/L),Mg2+会诱导SDS阴离子破坏水化膜,Zeta电位升高(-4.33 mV至-19.53 mV)但胶体稳定性降低;高浓度时(2 mol/L),Zeta电位稳定于-14 mV左右,Mg2+会构建一道次级水化膜,保证胶体的相对稳定性。利用微球溶胶考察了多孔滤膜的截留机制。实验结果表明:当Zeta电位高于-30 mV时,基于电荷排斥,大孔PSF超滤膜对平均粒径为53 nm的微球溶胶(粒径显著小于滤膜平均孔径)截留率可以达到90%;当Zeta电位低于-20 mV时,基于表面吸附,微滤膜(Φ=0.22μm)对平均粒径为137 nm的微球溶胶截留率均大于85.9%。
[Abstract]:Porous filtration membrane is widely used in the field of water treatment, and it has good retention ability to impurities. The study of its retention mechanism is of great theoretical significance for membrane treatment technology. It has been reported that the filtration mechanism of polystyrene, gold nanoparticles or red blood cells is studied by scanning electron microscope (SEM). The disadvantages of this study are that the physical and chemical properties (particle size, charge property) of the microspheres are poor in controllability and the cost is high. The testing process is complex. In this study, a kind of microspheres with controllable particle size and adjustable surface potential were prepared, and the mechanism of porous membrane interception was preliminarily studied by using microspheres. A method for preparation of submicron and nanoscale microspheres with controllable particle size was established by using polysulfone (PSF) and polystyrene (PS) mother liquor. The effects of preparation conditions on the particle size distribution of the microspheres were investigated. The particle size distribution mainly depends on the concentration of mother liquor, 0.05wt / 1.0wt) and the composition of coagulant, NaCl/ ultrapure water / PS mother liquor system, mainly depends on the dosage of mother liquor (100 渭 L / 1000 渭 L) and the kinds of organic solvents, such as NN- dimethylformamide and NN- dimethylacetamide, and increases the content of condensate. The particle size of ethanol microspheres becomes smaller, The particle size increased with the increase of NaCl salt content, while the content of sodium dodecyl sulfate (SDS) had no obvious effect on the particle size change of the microspheres. The surface potential of the microspheres was regulated by changing the concentration of co-existing ions SDS and MgCl _ 2 in the microsphere sol. By changing the concentration of SDS, it was found that increasing the concentration of SDS by 0.017 mmol / L ~ (1.01) mmol / L) potential increased ~ (3.22) MV ~ (-1) -61.77 MV ~ (-1), which was beneficial to the stability of the microspheres. The effect of MgCl _ 2 concentration on the surface potential of microspheres under different SDS concentrations was consistent. The experimental results show that when the concentration of MgCl _ 2 is changed, the Zeta potential of 0.02mol / L ~ (-1) mg _ (2) decreases significantly from -61.77 MV to -4.33 MV), but the colloidal stability is not changed, because the surface of microspheres adsorbs SDS to form a hydrated film, the hydration membrane plays a decisive role in the stability of colloid. At the medium concentration of 0.02 mol / L ~ (0.1) mol / L ~ (-1) mg _ (2), the SDS anion could destroy the Zeta potential of the hydration membrane and increase the Zeta potential to -4.33 MV to -19.53 MV), but the colloid stability was decreased, and at high concentration, the Zeta potential of 2 mol / L ~ (2) mg _ (2) could be stabilized at -14 MV or so and a secondary hydration membrane would be constructed to ensure the relative stability of the colloid. The retention mechanism of porous membrane was investigated by microsphere sol. The experimental results show that when the Zeta potential is higher than -30 MV, the rejection rate of the macroporous PSF ultrafiltration membrane can reach 90 when the average particle size is 53 nm, and the Zeta potential is less than -20 MV. On the basis of surface adsorption, the rejection rates of microspheres (桅 _ (0.22 渭 m) with average diameter of 137 nm were higher than 85.9 渭 m.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

【参考文献】