L-S相转化法与化学反应结合在醋酸纤维素膜制备过程中的应用
发布时间：2018-12-31 18:30
【摘要】：抗污染膜的制备是解决膜污染问题的根本途径。本论文以醋酸纤维素(CA)为膜材料,采用L-S相转化与化学反应相结合的制膜方法制备醋酸纤维素膜,并通过纯水通量、腐殖酸(HA)截留率等来考察醋酸纤维素膜的性能。首先,以CA为膜材料,富马酸为添加剂,用L-S相转化法与化学反应结合制备膜时,研究了不同溶剂(N,N-二甲基甲酰胺(DMF),N,N-二甲基乙酰胺(DMAc),N甲基吡咯烷酮(NMP),二甲基亚砜(DMSO))对膜性能的影响。实验结果表明:存在化学反应时,化学反应可以增加膜的凝胶速度,膜的断面结构为典型的非对称型,孔隙率增加;当使用NMP作为溶剂时,制备得到的膜的纯水通量高(162.7 L/(m2·h)),膜的孔径分布较狭窄,用L-S相转化与化学反应结合的方法法制备的膜用来过滤活性污泥后,去离子水清洗污染的膜,通量恢复率最高的是NMP为溶剂制备的膜(90.6%),并显示了其优越的抗污染性能。其次,通过在CA铸膜液中加入氧化石墨烯(GO)和纳米SiO2颗粒,用L-S相转化法与化学反应结合来制备膜GO-SiO2/CA,以期利用GO和SiO2的独特性能来改善CA膜的抗污染性能和机械性能。本文还比较了加入不同质量比的GO和SiO2所制备得到的膜的孔径分布曲线和环境扫描电镜图片。此外,还使用研究级万能显微镜,分别观察了不同制膜液组成在不同凝胶浴中的凝胶成膜动力学过程。实验结果表明:GO-SiO2/CA共混膜的孔隙率比CA膜的孔隙率更高,其孔隙增加到78.6%,并且GO-SiO2/CA共混膜的孔径分布更狭窄。此外,在铸膜液中添加了SiO2与GO后,膜的亲水性增强,GO-SiO2/CA共混膜的纯水通量比纯CA膜的提高了57.4%;当GO和SiO2的比例为50/50时,纯水通量最大达到255.7 L/(m2·h),该膜被腐殖酸污染后使用去离子水清洗的通量恢复率(FRR)达到89.9%。当GO为0.05 wt.%时,杨氏模量可达到220.2 MPa。由此可见,使用L-S相转化与化学反应相结合的制膜方法制备的GO-SiO2/CA共混膜具有较高的水通量,较优的抗污染能力,较强的机械性能和较好的长期运行稳定性。
[Abstract]:The preparation of anti-fouling membrane is the fundamental way to solve the problem of membrane fouling. In this paper, cellulose acetate membrane was prepared by L-S phase transformation and chemical reaction with cellulose acetate (CA) as the membrane material, and the pure water flux was used to prepare the cellulose acetate membrane. The (HA) retention rate of humic acid was used to study the properties of cellulose acetate membrane. Firstly, when CA was used as membrane material and fumaric acid was used as additive, when L-S phase inversion method was combined with chemical reaction to prepare the membrane, different solvents (N- N-dimethylformamide, (DMF), N-dimethylacetamide (DMAc),) were studied. Effect of N methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) on the properties of the membrane. The experimental results show that chemical reaction can increase the gel velocity of the membrane, and the cross section structure of the membrane is a typical asymmetric type, and the porosity of the membrane increases. When NMP was used as solvent, the membrane with high pure water flux (162.7 L / (m2) h), membrane had narrow pore size distribution. The membrane prepared by the method of L-S phase transformation and chemical reaction was used to filter activated sludge. The membrane prepared with NMP as solvent has the highest flux recovery rate (90.6%), and its excellent antifouling performance is shown. Secondly, the membrane GO-SiO2/CA, was prepared by adding graphene oxide (GO) and nanometer SiO2 particles into CA casting solution and combining L-S phase inversion method with chemical reaction. In order to improve the antifouling and mechanical properties of CA membrane by using the unique properties of GO and SiO2. The pore size distribution curves and environmental scanning electron microscopy (SEM) images of the membranes prepared by adding different mass ratios of GO and SiO2 were also compared. In addition, the kinetic process of film formation was observed by using a universal microscope with different composition of membrane preparation solution in different gel bath. The experimental results show that the porosity of GO-SiO2/CA blend membrane is higher than that of CA membrane, the porosity of GO-SiO2/CA blend membrane increases to 78.6, and the pore size distribution of GO-SiO2/CA blend membrane is narrower. In addition, when SiO2 and GO were added into the casting solution, the hydrophilicity of the membrane was enhanced, and the pure water flux of the GO-SiO2/CA blend membrane increased 57.4% than that of the pure CA membrane. When the ratio of GO to SiO2 is 50 / 50, the maximum pure water flux is 255.7 L / (m ~ 2 h),). The recovery rate of pure water flux is up to 89. 9% after the membrane is polluted by humic acid and washed with deionized water. When GO is 0. 05 wt.%, Young's modulus can reach 220.2 MPa.. It can be seen that the GO-SiO2/CA blend membrane prepared by combining L-S phase conversion with chemical reaction has higher water flux, better anti-pollution ability, stronger mechanical properties and better long-term operation stability.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893
本文编号：2396953
[Abstract]:The preparation of anti-fouling membrane is the fundamental way to solve the problem of membrane fouling. In this paper, cellulose acetate membrane was prepared by L-S phase transformation and chemical reaction with cellulose acetate (CA) as the membrane material, and the pure water flux was used to prepare the cellulose acetate membrane. The (HA) retention rate of humic acid was used to study the properties of cellulose acetate membrane. Firstly, when CA was used as membrane material and fumaric acid was used as additive, when L-S phase inversion method was combined with chemical reaction to prepare the membrane, different solvents (N- N-dimethylformamide, (DMF), N-dimethylacetamide (DMAc),) were studied. Effect of N methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) on the properties of the membrane. The experimental results show that chemical reaction can increase the gel velocity of the membrane, and the cross section structure of the membrane is a typical asymmetric type, and the porosity of the membrane increases. When NMP was used as solvent, the membrane with high pure water flux (162.7 L / (m2) h), membrane had narrow pore size distribution. The membrane prepared by the method of L-S phase transformation and chemical reaction was used to filter activated sludge. The membrane prepared with NMP as solvent has the highest flux recovery rate (90.6%), and its excellent antifouling performance is shown. Secondly, the membrane GO-SiO2/CA, was prepared by adding graphene oxide (GO) and nanometer SiO2 particles into CA casting solution and combining L-S phase inversion method with chemical reaction. In order to improve the antifouling and mechanical properties of CA membrane by using the unique properties of GO and SiO2. The pore size distribution curves and environmental scanning electron microscopy (SEM) images of the membranes prepared by adding different mass ratios of GO and SiO2 were also compared. In addition, the kinetic process of film formation was observed by using a universal microscope with different composition of membrane preparation solution in different gel bath. The experimental results show that the porosity of GO-SiO2/CA blend membrane is higher than that of CA membrane, the porosity of GO-SiO2/CA blend membrane increases to 78.6, and the pore size distribution of GO-SiO2/CA blend membrane is narrower. In addition, when SiO2 and GO were added into the casting solution, the hydrophilicity of the membrane was enhanced, and the pure water flux of the GO-SiO2/CA blend membrane increased 57.4% than that of the pure CA membrane. When the ratio of GO to SiO2 is 50 / 50, the maximum pure water flux is 255.7 L / (m ~ 2 h),). The recovery rate of pure water flux is up to 89. 9% after the membrane is polluted by humic acid and washed with deionized water. When GO is 0. 05 wt.%, Young's modulus can reach 220.2 MPa.. It can be seen that the GO-SiO2/CA blend membrane prepared by combining L-S phase conversion with chemical reaction has higher water flux, better anti-pollution ability, stronger mechanical properties and better long-term operation stability.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893
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