A study on thermally and chemically stable multifunctional membranes

热化学稳定性多功能膜的研究

基本信息

批准号：
10305060
负责人：
TOMITA Akira
金额：
$ 24.32万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The porosity of an anodic aluminum oxide film consists of an array of parallel and straight channels with a uniform diameter at nanometer level. Because of the presence of such nanochannels, the film has been used as a membrane for ultrafilitration. This membrane filter however, suffers from its poor chemical stability both in acid and alkaline solutions. In order to circumvent such poor stability, we have prepared a carbon-coated membrane from an anodic oxide film and then chemically-modified its carbon surface by either oxidation or fluorination treatment. In the present study, we use the membrane for pervaporation separation of water/ethanol mixture and investigate the effect of such modification on the pervaporation performance.When pyrolytic decomposition of propylene was carried out over an anodic aluminum oxide film, uniform carbon coating on the film was achieved. The carbon deposition process decreased the channel diameter from 30 to 20 nm, but left the whole channel structure intact. Further fluorination or HNO_3 treatment did not alter the channel structure. Gas permeation through these films was found to be principally governed by Knudsen diffusion. In the pervaporation separation of water/ethanol mixture, preferential permeation of water was observed in the fluorinated films, although the untreated and oxidized carbon-coated films did not show any selectivity. This work demonstrated that, even if pore diameter is as large as 20 nm, a suitable surface modification to pore wall makes it possible to endow a membrane with selectivity in pervaporation separation.

阳极氧化铝膜的孔隙由一系列平行且笔直的通道组成，这些通道具有纳米级的均匀直径。由于这种纳米通道的存在，该薄膜已被用作超滤膜。然而，这种膜过滤器在酸性和碱性溶液中化学稳定性较差。为了避免这种较差的稳定性，我们用阳极氧化膜制备了碳涂层膜，然后通过氧化或氟化处理对其碳表面进行化学改性。在本研究中，我们使用该膜对水/乙醇混合物进行渗透汽化分离，并研究这种改性对其渗透汽化性能的影响。当丙烯在阳极氧化铝膜上进行热解分解时，膜上形成均匀的碳涂层已实现。碳沉积过程将通道直径从 30 nm 减小到 20 nm，但整个通道结构保持完整。进一步氟化或HNO_3处理不会改变通道结构。发现这些薄膜的气体渗透主要受克努森扩散控制。在水/乙醇混合物的渗透蒸发分离中，在氟化膜中观察到水的优先渗透，尽管未经处理和氧化的碳涂层膜没有表现出任何选择性。这项工作表明，即使孔径大至20 nm，对孔壁进行适当的表面修饰也可以赋予膜渗透汽化分离的选择性。