Fabrication of polyelectrolyte complex/graphene oxide nanocomposite membrane for pervaporation dehydration

• Main Authors: Wei-Ting Yang, 楊偉廷
• Other Authors: Wei-Song Hung
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/82111236794330922973

碩士 === 中原大學 === 化學工程研究所 === 102 === Abstract This study used the protection and deprotection methods for acids to induce a complexation reaction of cationic branched polyethylenimine (bPEI) and anionic polyelectrolyte sodium carboxymethyl cellulose (CMCNa) to form a soluble polyelectrolyte complex (PEC). In addition, this study successfully dissolved graphene oxide (GO) in a bPEI solution and induced a complexation reaction of GO and CMCNa to produce GO–PEC nanocomposites, which were in turn used to fabricate pervaporation composite films. An attenuated total reflection Fourier transform infrared spectroscope, contact angle analyzer, field emission electron microscope, atomic force microscope, and variable monoenergy slow positron beam were used to examine the chemical structure, hydrophilicity, physical morphology, and surface roughness of the films and the free volume between the layers of the films. This study explored the effects of various concentration levels of GO and various degrees of complexation on the chemical structure, microstructure, and pervaporation performance of the film. The experiment results indicated that a GO–PEC 0.7 nanocomposite film fabricated using 100-ppm GO with a complexation ratio of 0.7 optimally separated 90-wt% aqueous methanol solution at 40 °C. The permeation amount was 636 g/m2h, and the water concentration at the permeate side was 74 wt%. The separation selectivity of GO–PEC 0.7 nanocomposites was superior to that of PEC 0.70 composite films (the permeation amount was 662 g/m2h and the water concentration at the permeate side was 64 wt%). Subsequently, this study investigated the effects of pervaporation conditions (including feed temperature, feed concentration, and alcohol solutions with various carbon numbers) on pervaporation separation. Compared with PEC composite films, GO–PEC nanocomposite films effectively inhibited film swelling. In addition, the layered structure of GO provided additional permeation pathways for feed, thereby yielding superior pervaporation separation performance. By using slow positron beam analysis, this study found that enhanced complexation degree increased the density of the arrangement between polyelectrolyte complexes.