Exploring distillation-pervaporation hybrid process in a single column using hollow fiber pervaporation composite membranes as structured packing

Abstract

This study developed a novel strategy for azeotrope separation such as ethanol-water binary system. Distillation-pervaporation hybrid process was employed by using hollow fiber pervaporation composite membranes as structured packing in a single hybrid column rather than using pervaporation as an externally connected unit of the distillation column. The separating limitation of azeotrope challenged in conventional distillation could be readily overcome by continually removing water from the hybrid system via pervaporation. The competition between distillation and pervaporation has been found to be cause of unexpected concentration distribution in the hybrid column. The mass flux of mixture decreased with time whereas the selectivity of water to ethanol first increased then decreased with time. Analysis of this system illustrated that the increase in heating power and membrane area shortened time for obtaining certain content of ethanol in the mixture. However, faster decline in mass flux occurred due to an increase in the removal rate of water. With respect to its simplicity, efficiency and broad applicability, this hybrid process is expected to provide a benchmark for the enhancement of distillation-pervaporation process by hollow fiber membrane packing.