Pervaporation performance of PDMS/PVDF/Polyester multilayer membrane in ethanol/water separation

Publish Year: 1397
نوع سند: مقاله کنفرانسی
زبان: English
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ICESIT01_199

تاریخ نمایه سازی: 6 بهمن 1397

Abstract:

With the decrement of fossil fuels, the increment of oil prices and environmental requirements, there is an increasing need for the development of new energy sources, especially renewable energies such as ethanol. Membrane technology is one of the most effective, attractive and energy saving separation processes that is flourished over the world recently. Pervaporation (PV) is a membrane-based process which is used to separate the components of a liquid mixture. Polydimethylsiloxane (PDMS) membrane has attracted increasing attention due to its potential application in the separation of organic–organic liquid mixtures and removing volatile organic compounds from water and soil. However, the selectivity of neat PDMS membrane reported in papers is very low. Much effort has been expended to improve the overall PV performance of PDMS membranes due to its low-cost and easiness to handle, but there was no development in selectivity or permeation flux of neat PDMS membranes. Since Polyvinylidene fluoride (PVDF) is a porous membrane, dilute PDMS homogeneous solution is liable to plugging in the pores of PVDF membrane surface and may lead to the notable increase in permeation resistance across the interface of PVDF and PDMS for small molecules. In this paper, a multi-layer PDMS/PVDF composite membrane with an alternative configuration was prepared and subsequently applied in ethanol recovery from an ethanol-water mixture by PV process. The porous PVDF support layer was obtained by coating on the PET with phase inversion method. The selective layer (PDMS) was coated on the surface of PVDF porous substrate. The multi-layer composite membrane had the effective area of about 20 cm2 and the PET/PVDF/PDMS layers had the thickness of about 85/35/10 µm respectively. Atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy was performed on PDMS layer and x-ray diffraction (XRD) on multilayer membrane. The effect of feed temperature and feed ethanol concentration on the pervaporative properties of PDMS/PVDF composite membrane were investigated and the results were compared with the neat PDMS membrane. PV tests were performed in different temperatures(30,45,60,75) and various feed ethanol concentrations(5,10,15,20). Each experiment was performed three times and the average value was considered. It was found that, the total flux of the composite membrane increases with the increment of feed temperature, whereas the separation factor decreased. Experimental results showed that the membrane synthesized in this study had better separation factors at low ethanol concentrations in the feed and also in low temperatures. Maximum separation factor about 32 was obtained at 30⁰C and 5 wt% of ethanol concentration in the feed. In addition, the maximum flux was obtained at 75⁰ C and 15 wt%. The optimum conditions of selectivity and flux was tested on single layer PDMS membrane. Less separation factor and flux was obtained in the similar condition which indicates better efficiency of the multilayer membrane.

Authors

Shiva Shafiee

Separation Processes Research Group (SPRG), Department of Engineering, University of Kashan, Kashan, Iran

Mohammad Paki

Separation Processes Research Group (SPRG), Department of Engineering, University of Kashan, Kashan, Iran

Morteza Asghari

Associate Professor of Chemical Engineering, Separation Processes Research Group (SPRG), Department of Engineering, University of Kashan, Kashan, Iran