利用多巴胺粘合特性调控膜内多级结构和多重作用的研究

发布时间：2018-05-01 21:13

本文选题：气体分离 + 杂化膜　；参考：《天津大学》2015年硕士论文

【摘要】：开发高效率、低能耗的CO_2捕集技术是实现温室气体减排和能源气体净化的共性关键问题。膜技术是最具发展前景的CO_2捕集技术之一,开发高渗透性高选择性CO_2分离膜材料则是膜技术用于CO_2捕集的重要需求。为提高有机-无机杂化气体分离膜的分离性能,利用多巴胺的氧化聚合以及表面改性的特性,制备出三种基于多巴胺的气体分离杂化膜。利用多巴胺(DA)在弱碱性水溶液中自聚交联的特性,其中的儿茶酚基团和氨基基团与聚乙烯醇(PVA)中的羟基(—OH)形成氢键作用,实现了DA对PVA的物理交联,将DA-PVA铸膜液旋涂于PES基膜上制备了DA-PVA/PES纳米杂化水凝胶气体分离复合膜。考察了DA浓度和自聚时间对PVA基质物理化学性质的影响,包括亲水性、水含量、热稳定性及自由体积分数等;研究了加湿状态下膜对CO_2/CH4混合体系的分离性能。其中,DA-PVA(B3)/PES膜的分离性能最优,其CO_2/CH4选择性达到43.2,为纯膜的143.85%。综合DA-PVA/PES膜的表征结果和分离性能,提出了CO_2和CH4膜内的传质模型。利用聚多巴胺(PDA)粒子上活性儿茶酚基团对胺基(—NH2)封端小分子的固定作用,以四乙烯五胺(TEPA)作为CO_2促进传递固定载体,将TEPA通过共价键固定在PDA颗粒上,制备出PDA/TEPA颗粒,并将其填充至聚氧乙烯基高分子Pebax?MH 1657中制备了Pebax-PDA/TEPA气体分离杂化膜。通过元素分析,计算得到PDA/TEPA颗粒中TEPA的负载量为11.86 wt%。SEM照片显示PDA/TEPA粒子粒径均匀,为180~220 nm。探索了Pebax-PDA/TEPA杂化膜加湿状态下对CO_2/CH4混合体系的分离性能。Pebax-PDA/TEPA(5)膜取得了最优的分离性能,CO_2/CH4选择性为27.53,为纯膜的148.49%。利用PDA对金属离子的螯合作用以及对金属离子的无电镀沉积能力,以螯合固定在聚多巴胺球(~80 nm)上的Ag+离子作为CO_2促进传递固定载体,多巴胺还原的金属Ag颗粒(~20 nm)作为膜结构调控介质,制备出了两面神‖颗粒(Janus particle),并将其填充至Pebax?MH 1657中制备Pebax-Janus气体分离杂化膜。Pebax-Janus杂化膜气体分离性能出现了反tradeoff效应,即CO_2通量和CO_2/CH4选择性同时提高。Pebax-Janus杂化膜在纯气体系中所取的最佳分离性能为CO_2通量150 Barrer、CO_2\CH4选择性26.3以及CO_2\N2选择性72.5。此外提出了CO_2在Pebax-Janus杂化膜的传质模型。
[Abstract]:Developing high efficiency and low energy consumption CO_2 capture technology is the common key problem of greenhouse gas emission reduction and energy gas purification. Membrane technology is one of the most promising CO_2 trapping technologies, and the development of high permeability and high selectivity CO_2 separation membrane materials is an important requirement of membrane technology for CO_2 trapping. In order to improve the separation performance of organic-inorganic hybrid gas separation membranes, three dopamine-based gas separation hybrid membranes were prepared by oxidation polymerization and surface modification of dopamine. In this paper, the self-poly-crosslinking properties of dopamine (DA) in weak alkaline aqueous solution were used. The catechol-group and amino group formed hydrogen bond with hydroxyl group (OH) in PVA, and the physical crosslinking of DA to PVA was realized. DA-PVA nano-hybrid hydrogel gas separation composite membrane was prepared by spin-coating of DA-PVA film on PES substrate. The effects of DA concentration and self-polymerization time on the physical and chemical properties of PVA matrix, including hydrophilicity, water content, thermal stability and free volume fraction, were investigated. The CO_2/CH4 selectivity of DA-PVA3 / PES membrane was 43.2, which was 143.85% of that of pure membrane. Based on the characterization results and separation properties of DA-PVA/PES membranes, the mass transfer models in CO_2 and CH4 membranes were proposed. Using the immobilization of the active catechol group on the poly (dopamine) (PDA) particle to immobilize the small molecule of amino-amine-NH _ 2, the PDA/TEPA particles were prepared by immobilization of TEPA onto the PDA particles by covalent bonding with tetraethylenepentylamine (Tepa) as the transport carrier. Pebax-PDA/TEPA gas separation hybrid membrane was prepared by filling it into polyvinyl polymer Pebax?MH 1657. The results of element analysis show that the loading amount of TEPA in PDA/TEPA particles is 11.86 wt%.SEM. The results show that the size of PDA/TEPA particles is uniform, which is 180 ~ 220nm. The separation performance of Pebax-PDA/TEPA hybrid membrane for CO_2/CH4 mixed system under humidification condition. Pebax-PDA-TEPA-5) membrane obtained the best separation performance. The selectivity of CO2 / Ch _ 4 is 27.53, which is 148.49g of pure membrane. Using the chelation of PDA on metal ions and the ability of electroplating deposition of metal ions, Ag ions immobilized on the polydopamine spheres (80 nm) were used as the carrier for CO_2 transfer. The dopamine reduced metal Ag particles (20 nm) were used as the membrane structure control medium to prepare Pebax-Janus gas separation hybrid membrane .Pebax-Janus hybrid membrane, which was filled in Pebax?MH 1657, and the gas separation performance of Pebax-Janus gas separation hybrid membrane showed anti-tradeoff effect. That is to say, both CO_2 flux and CO_2/CH4 selectivity can improve the separation performance of .Pebax-Janus hybrid membrane in pure gas system. The best separation performance is CO_2 flux 150 Barrern C _ 2\ CH4 selectivity 26.3 and CO_2\ N _ 2 selectivity 72.5. In addition, a mass transfer model of CO_2 in Pebax-Janus hybrid membrane was proposed.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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