填充二维材料杂化膜的制备与渗透蒸发过程强化

发布时间：2018-03-20 02:07

本文选题：杂化膜　切入点：渗透蒸发　出处：《天津大学》2015年硕士论文　论文类型：学位论文

【摘要】：开发高性能膜材料是渗透蒸发过程强化的关键,高分子-无机杂化膜兼具高分子膜和无机膜的优点,有望同时获得高渗透性、高选择性和强稳定性。本论文面向清洁燃料生产的国家重大需求,以渗透蒸发乙醇脱水的过程强化为目标,以膜材料的理性设计为手段,以膜结构的优化调控为核心,制备了多种填充二维材料的渗透蒸发杂化膜。杂化膜具有适宜的界面形态、筛分功能、自由体积和亲疏水性,实现了乙醇/水分离的高效强化,为渗透蒸发膜的制备与过程强化开辟了新途径。为研究二维材料作为渗透蒸发杂化膜填充剂的优势,制备了两种沸石咪唑骨架材料(ZIF-8),颗粒状的ZIF-8P和片状的ZIF-8S,分别与海藻酸钠(SA)共混制备杂化膜。系统表征了杂化膜的结构,评价了其分离性能。在SA-ZIF-8P杂化膜内,ZIF-8P各向同性的形貌和较弱的界面相互作用,削弱了其纳米孔道的筛分功能。而ZIF-8S的二维形貌和有序取向增强了其筛分功能,强化了SA-ZIF-8S杂化膜的扩散过程。当ZIF-8S填充量为4 wt.%,杂化膜的渗透通量为1218 g/(m2h),分离因子为1840。为实现组分溶解过程和扩散过程的同时强化,将氧化石墨烯(GO)引入SA基质制备杂化膜。SA-GO杂化膜呈现出GO有序曲线的“砖-泥”形貌、反常的结晶度变化和增大的自由体积分数。通过GO的物理化学结构的调控,优化了杂化膜的界面形态、自由体积特性和亲疏水性,构建了水分子快速传递的通道,强化了杂化膜的筛分功能,提高了杂化膜的分离性能。SA-GO杂化膜的渗透通量为1699 g/(m2h),分离因子为1566,且具有较好的长期操作稳定性。为制备更高性能的渗透蒸发膜,合成了具有二维多孔的g-C3N4纳米片(CNs),并与SA共混制备杂化膜。CNs超薄的结构和较高的孔隙率可进一步降低水分子传递阻力,CNs均一的孔径分布能提供更加精密的筛分功能,CNs的高纵横比和有序取向进一步强化了其筛分能力。通过CNs对杂化膜界面形态、自由体积和亲疏水性的进一步优化,杂化膜的分离性能得到进一步提高。当CNs填充量为3 wt.%时,渗透通量高达2469 g/(m2h),分离因子为1653。杂化膜具有较高的热稳定性、机械稳定性、抗溶胀能力和良好的长期操作稳定性。
[Abstract]:The development of high performance membrane materials is the key to the enhancement of pervaporation process. Polymer-inorganic hybrid membrane has the advantages of both polymer membrane and inorganic membrane, so it is expected to obtain high permeability at the same time. High selectivity and strong stability. This paper aims at strengthening the process of dehydration of ethanol by pervaporation, taking the rational design of membrane material as the means, and taking the optimization of membrane structure as the core, to meet the important national demand of clean fuel production. A variety of permeable evaporative hybrid membranes filled with two-dimensional materials were prepared. The hybrid membranes had suitable interface morphology, screening function, free volume and hydrophobicity, so the ethanol / water separation was effectively strengthened. It opens up a new way for the preparation and process strengthening of pervaporation membrane, and studies the advantages of two-dimensional materials as fillers for pervaporation hybrid membrane. Two kinds of zeolite imidazole matrix materials, ZIF-8, granular ZIF-8P and flake ZIF-8S, were prepared and blended with sodium alginate respectively to prepare hybrid membranes. The structure of hybrid membranes was systematically characterized. The isotropic morphology and weak interfacial interaction of ZIF-8P in the SA-ZIF-8P hybrid film weakened the screening function of the nano-pore, while the two-dimensional morphology and ordered orientation of ZIF-8S enhanced the sieving function. The diffusion process of SA-ZIF-8S hybrid membrane was enhanced. When the amount of ZIF-8S filled was 4 wt., the permeation flux of the hybrid membrane was 1218 g / m ~ (2) h ~ (-1), and the separation factor was 1 840. The hybrid membrane, SA-GO hybrid membrane, was prepared by introducing graphene oxide (GOO) into SA matrix. The hybrid membrane showed the "brick mud" morphology of go ordered curve, abnormal crystallinity change and increased free volume fraction. The interface morphology, free volume characteristic and hydrophobicity of the hybrid membrane were optimized, and the fast transfer channel of water molecules was constructed, and the screening function of the hybrid membrane was enhanced. The performance of hybrid membrane was improved. The permeation flux of SA-GO hybrid membrane was 1699 g / m ~ (-2) h ~ (-1), the separation factor was 1566, and it had good long-term operational stability. G-C _ 3N _ 4 nanochips with two-dimensional pores were synthesized, and the hybrid membrane 路CNS was prepared by blending with SA. The ultrathin structure and high porosity can further reduce the water molecular transfer resistance and the uniform pore size distribution of CNs can provide more precise screening work. The high aspect ratio and ordered orientation of CNS further enhanced its screening ability. The interfacial morphology of hybrid membranes was observed by CNs. With the further optimization of free volume and hydrophobicity, the separation performance of hybrid membrane was further improved. When the CNs content was 3 wt.wt%, the permeation flux was 2469 g / m ~ (-2) h ~ (-1) and the separation factor was 1653. The hybrid membrane had high thermal stability and mechanical stability. Anti-swelling ability and good long-term operation stability.
【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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