Polyetherimide/nano graphene oxide membrane for dehydration of n-butanol by pervaporation process
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Date
2018
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Universiti Teknologi Malaysia
Abstract
Pervaporation is one of the promising technologies which is an indispensable component for chemical separations with low energy consumption, minimum contamination and ability to break up azeotropic mixtures. The key success of pervaporation process is dependent on the membrane features (chemical components and morphology). Many researchers have demonstrated different techniques for promoting the membrane features, however moving forward the data lack the scope and depth of understanding of the membrane fabrication techniques in dehydration of biofuel. Previous research has addressed membrane modification techniques which complicate fabrication procedures and are neither economical nor energy efficient in providing new fabrication techniques that could help resolve current drawbacks of membrane fabrication. In this work, dry-thermal (PMDT), thermal treatment (PMTT) and dry-thermal treatment (PMDTT) techniques were used to fabricate sponge-like, dense and thin film composite structure membranes with the similar solvent composition, respectively. Synthesized graphene oxide (GO) nanoplates, have become the best candidate to be adopted as a nanofiller in the membrane matrices owing to its unique properties. Incorporating graphene oxide into polyetherimide improved the diffusion rate and water purity of permeant. Graphene oxide effects were highlighted by applying neat polyetherimide membrane for dehydration of n-butanol-water mixtures. Different fabrication techniques applied to provide ideal thin film composite (PMDTT) for dehydration of n-butanol. An ideal membrane fabrication is promising with stable permeation rate and separation factor performance. Although permeation performance was noticeable by dry-thermal membrane, thermal treatment techniques were used to improve the separation factor of dry-thermal membrane which transformed the morphology and enhanced separation performance. To fabricate a membrane the current drawbacks were overcome by applying dry-thermal treatment which resulted in a thin film composite membrane with a significant dehydration permeation rate of 1128 g/m2 h at 50 °C and 0.1 bar pressure and the separation factor indicated better performance at 30 °C for almost 99.3. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were used to verify that the synthesized graphene oxide is nano material, presence of functional groups or degree of oxidization and quality of graphene oxide synthesized. The membranes were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and contact angle measurement (CAM) to show the different physiochemical properties of each membrane, morphological cross-section structure, d-spacing between filler, intensity of filler and surface roughness. The pervaporation performance by PMDTT membrane exhibited better performance than PMDT and PMTT. This result illustrates the benefit of morphological structure on the pervaporation performance by the novel fabrication structure
Description
Thesis (PhD.)
Keywords
Pervaporation, Membranes (Technology), Biomass energy—Research