PVA/UiO-66 mixed matrix membranes for n-butanol dehydration via pervaporation and effect of ethanol

Abstract

In this work, pervaporative mixed matrix membranes (MMMs) composed of porous UiO-66 filler newly-synthesized and poly (vinyl alcohol) (PVA) have been investigated for dewatering n-butanol (BuOH) from BuOH/H2O and BuOH/ethanol/H2O solutions. The influences of the filler loading, feed concentration and feed temperature on the membrane dehydration performance are investigated in detail in terms of pervaporation flux/separation factor, pervaporation separation index and component permeance/selectivity. It is found that with the increase in feed water concentration or temperature, total permeation flux across the MMM substantially rises while the dehydration separation factor decreases considerably. With the increase in feed temperature, pronounced increase in the driving force is resulted, yielding the decline in the partial permeance and water/n-butanol selectivity but increase in the component flux. As the water content increases, the water permeance and water/n-butanol selectivity are reduced while both BuOH flux and permeance increase. Over the filler loading range considered here, the MMM with 15 wt% UiO-66 has reached the largest pervaporation separation index of 2560 kg/m2·h at 70 °C and 10 wt% water in the feed. In the case of using 10 wt% ethanol for BuOH in the feed, the dewatering separation performance has varied substantially as compared to the binary feed, leading to reduced separation factor and elevated permeation flux for the 15 wt% UiO-66 filled MMM. In the meantime, the MMM has maintained excellent separation performance over a testing duration of 240 h. Our results show that pervaporative UiO-66/PVA MMMs have demonstrated great potential in practical BuOH dehydration applications.