Development of composite hollow fibre membrane for the separation of volatile organic compounds

Abstract

The emission of volatile organic compounds (VOCs) has become one of the most major concerns in atmospheric pollution. In addition, venting of these VOCs to atmosphere represents a significant loss of valuable materials and energy resources. The overall objective of this research program is to develop polydimethylsiloxanevi-polyvinylidene fluoride (PDMSvi-PVDF) hollow fibre composite membranes for efficient removal or recovery of VOCs from waste air streams by vapour permeation. Porous (PVDF) hollow fibres spun via dry-wet phase immersion method were used as substrates, whereby a homogenous thin layer of oligo-PDMSvi is coated via a developed four-step coating method. The important factors affecting the integrity and performance of the fabricated composite membrane have been examined in some detail, and the optimal conditions were determined. The PDMSvi-PVDF composite membranes prepared under optimal coating conditions have been applied for the separation of a wide variety of VOCs, including benzene, chloroform, acetone etc. Effects of feed mode, feed concentration, feed flow rate and operating temperature on the performance of the composite membranes are presented and discussed. The developed PDMSvi-PVDF has been shown to be excellent composite membrane of VOC separation. Very high removal and recovery efficiencies were obtained for most of the VOCs examined. Sorption equilibria and kinetics of a number of VOCs in the oligo-PDMSvi polymer were studied via a gravimetric method. Finally, Process model for vapour permeation in the PDMSvi-PVDF hollow fibre membrane module has been developed to fit the experiment data for several VOC/N2 systems, namely, benzene/N2, chloroform/N2 and acetone/N2.