基于超支化聚硅氧烷的渗透汽化复合膜制备及分离水中低分子醇性能研究

发布时间：2018-02-20 05:21

本文关键词： 超支化聚硅氧烷渗透汽化多层复合膜 2 3-丁二醇正丁醇　出处：《江南大学》2015年硕士论文　论文类型：学位论文

【摘要】：低分子醇如正丁醇,2,3-丁二醇作为可再生生物燃料及重要化学前躯体,皆可由发酵法制备,如何经济有效地分离低分子醇具有重要的意义。渗透汽化分离液体混合物具有能耗低,对环境污染小,操作简单等特点,广泛应用于有机物脱水,水中有机物分离及有机混合物分离。在研究新型的渗透汽化膜的过程中,超支化聚合物相比于传统线性聚合物,其分子含有大量末端官能团,具有分子缠绕少,反应活性高,流变性能优异,自由体积大等优点,受到了广泛关注。超支化聚合物应用于渗透汽化膜一般具有较高的通量,但是主要应用于渗透汽化有机物脱水和有机混合物分离,而将超支化聚合物应用于渗透汽化分离水中有机物的研究较少。本文在超支化聚硅氧烷的基础上,深入研究制备新型超支化聚合物膜用于渗透汽化分离水中低分子醇。本文基于超支化聚硅氧烷高度支化的分子结构,分别制备了以超支化聚硅氧烷膜为支撑层和分离层的渗透汽化复合膜用于分离水中正丁醇,同时研究了渗透汽化与萃取耦合分离提纯水中2,3-丁二醇,其主要实验内容为:(一)通过AB2型单体一步法合成了超支化聚硅氧烷(HPSi O),并以HPSi O-c-PDMS-1为中间层,VTES-c-PDMS为表层分离层制备了具有多层结构的复合膜;(二)制备了不同HPSi O含量的HPSi O-c-PDMS-3复合膜;对上述复合膜膜形态及性能进行分析,并对其用于渗透汽化分离水中正丁醇进行研究。(三)通过萃取法绘制2,3-丁二醇/水/正丁醇的三元相图,将所选萃取相先后通过PVA膜及HPSi O-c-PDMS-2膜长时间渗透汽化分离,测定渗余液中2,3-丁二醇浓度判断是否达到分离提纯2,3-丁二醇的目的。其实验结果表明:(1)合成了较高支化度的超支化聚硅氧烷,复合膜为具有明显多层结构的超支化渗透汽化膜。随着选择层VTES-c-PDMS层中PDMS分子量的增加,膜的渗透通量降低,对丁醇和水的渗透性降低,而分离因子和选择性增加。其中,FHPV-3多层复合膜的通量为450g/(m2h),分离因子为28。随着料液温度的增加,多层复合膜的通量及分离因子均呈上升趋势;随着料液浓度的增加,多层复合膜的通量上升而分离因子变化较小,通过渗透液浓度可知,当原料液浓度为2.5wt%时,透过液浓度为42wt%,渗透效果提升明显。(2)HPSi O-c-PDMS-3复合膜中,当HPSi O含量低于50wt%时,HPSi O以球状形式分布于有机膜基质中,当HPSi O含量高于50wt%时,HPSi O以链状形式分布于有机膜基质中。HPSi O含量的增加,膜的疏水性下降,其渗透汽化对丁醇渗透性降低,膜选择性下降,而渗透通量上升。当HPSi O含量为37.5wt%时,膜的通量为229.85g/(m2h),分离因子为39.5,其渗透通量达到最大。HPSi O在膜基质中的分布形式不影响渗透汽化膜随料液温度,料液浓度变化的趋势。(3)通过溶液萃取法,绘制了24oC下2,3-丁二醇/正丁醇/水的三元相图。通过PVA膜及HPSi O-c-PDMS-2膜渗透汽化性能随温度的变化确定PVA膜的连续化操作温度为40oC,HPSi O-c-PDMS-2膜连续化操作温度为50oC~60oC。PVA膜渗透汽化时间达10h时,渗余液中水的质量浓度从31.27wt%下降到10.85wt%,2,3-丁二醇的质量浓度从10.56wt%上升到14.09wt%;随着HPSi O-c-PDMS-2膜渗透汽化时间达48h时,渗余液中2,3-丁二醇的质量浓度达到69.41wt%。
[Abstract]:Low molecular weight alcohols such as butanol, 2,3- butanediol as renewable biofuels and chemical precursors can be prepared by fermentation, how to effectively separate low molecular weight alcohols has important significance. The pervaporation separation of liquid mixtures with low energy consumption, little environmental pollution, simple operation and other characteristics, widely used in organic matter dehydration, separation of Organics in water and organic mixture separation. In the process of pervaporation membrane model in hyperbranched polymers compared with traditional linear polymers, the molecules of which contain a large number of terminal groups, with molecular winding less, high reaction activity, excellent rheological properties, the advantages of the free volume is large, hyperbranched has attracted widespread attention. The polymer used in pervaporation membrane with high flux, but mainly used in pervaporation dehydration of organic and organic mixture separation, the hyperbranched polymer should be For the study of pervaporation separation of organics in the water less. Based on hyperbranched polysiloxane, in-depth study of preparation of novel hyperbranched polymer membrane for pervaporation separation of water ethanol. The low molecular weight hyperbranched polysiloxane highly branched molecular structure based on respectively prepared by Hyperbranched polysiloxane membrane for pervaporation composite membrane support layer and separation layer for the separation of water and n-butanol on the permeation and separation and purification of water extraction of PVMR 2,3- butanediol, its main experiments: (a) by AB2 single step synthesis of hyperbranched polysiloxane (HPSi O), and HPSi O-c-PDMS-1 as the middle layer, VTES-c-PDMS the surface separation composite film has a multilayer structure prepared by layer; (two) HPSi O-c-PDMS-3 HPSi composite films with different O content were prepared; the composite membrane morphology and properties were analyzed, And the water for the pervaporation separation of n-butanol were studied. (three) by extraction method to draw 2,3- butylene glycol / water / three phase diagram of n-butanol, the selected extraction phase has passed PVA membrane and HPSi membrane O-c-PDMS-2 long time pervaporation separation, determination of whether the infiltration of 2,3- butanediol concentration in the raffinate to judge purification of 2,3- butanediol to separation. The experimental results show that: (1) high degree of branching hyperbranched polysiloxane were synthesized. The composite film has obvious multilayer structure of hyperbranched pervaporation membrane. With the increase of PDMS selection molecular layers of VTES-c-PDMS amount, the permeate flux decreased and the permeability of butanol and water the lower, while the separation factor and selectivity increased. Among them, FHPV-3 multilayer composite membrane flux is 450g/ (m2h), the separation factor is 28. with the increase of feed temperature, the flux and separation factor of multilayer films increased with; With the increase of feed concentration, multilayer composite membrane flux increases the separation factor of small changes, the permeate concentration shows that when the feed concentration is 2.5wt%, the liquid concentration is 42wt%, significantly enhance the penetration effect. (2) HPSi O-c-PDMS-3 composite film, when the HPSi O content is lower than 50wt%, HPSi to O the globular form distributed in the organic membrane matrix, when the HPSi content of O was higher than 50wt%, increased HPSi O chain in the form of distribution in the.HPSi O content of organic membrane matrix, hydrophobic membrane decreased, the pervaporation of butanol permeability decreased, membrane selectivity decreased, while the permeation flux increased when the HPSi content is O. 37.5wt%, the membrane flux is 229.85g/ (m2h), the separation factor was 39.5, distribution of the permeation flux reaches the maximum at.HPSi O in the membrane matrix does not affect the pervaporation membrane with the feed temperature, feed concentration change trend. (3) by solvent extraction, drawing 24oC 2,3- butanediol / n-butanol / water three phase diagram by PVA. O-c-PDMS-2 membrane and HPSi membrane pervaporation performance changes with temperature to determine the continuous operating temperature of PVA film is 40oC, HPSi O-c-PDMS-2 film continuous operation temperature of 50oC~60oC.PVA membrane pervaporation time was 10h, the concentration of residual liquid water infiltration decreased from 31.27wt% to 10.85wt%, the mass concentration of 2,3- butanediol increased from 10.56wt% to 14.09wt%; HPSi with O-c-PDMS-2 membrane pervaporation time was 48h, the concentration of infiltration in the raffinate of 2,3- butanediol reached 69.41wt%.

【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

【参考文献】