Temperature-enhanced water selectivity in polyvinyl alcohol mixed matrix membranes filled with poly(2-hydroxyethylmethacrylate)-grafted mesoporous silica nanoparticles (PVA/MSNs-g-PHEMA MMMs)

Abstract

Abstract Temperature-enhanced water selectivity of MMMs was demonstrated for the dehydration pervaporation of ethanol solutions. The MMMs synthesized from Polyvinyl alcohol embedded with Poly(2-hydroxyethylmethacrylate)-grafted mesoporous silica nanoparticles revealed a concomitant increasing of the water selectivity and the water flux upon raising feed solution temperature from 30\xa0°C to 60\xa0°C. This phenomenon is rarely observed in PVA-based MMMs in which the water selectivity usually declines with increasing feed temperature. Remarkably, the temperature enhancing effect was intensified with increasing amount of the grafted PHEMA on MSNs. The enhancement of the water selectivity stems from the superior water absorption selectivity to the water diffusion selectivity because the water absorption by the MMMs is endothermic which gives rise to the favorable absorption as raising feed solution temperature. The incorporation of MSNs-g-PHEMA resulted in improving of both flux and the water selectivity because the mesoporous structure of MSNs-g-PHEMA provides unrestricted and hydrophilic paths for the water permeation.