Removal of volatile organic compounds from aqueous solutions applying thermally driven membrane processes. 1. Thermopervaporation

Temperature driven membrane thermopervaporation was studied in this work. Impact of various experimental conditions (feed temperature – T f , type of membrane, type of organic solvent in binary aqueous mixture, feed composition) on transport and selectivity in TPV was investigated experimentally. Two commercially available dense PDMS based membranes (Pervatech and Pervap 4060) were utilized during TPV experiments in contact with pure water and binary aqueous mixtures of acetone, butanol and ethanol. Intrinsic properties (permeance and selectivity coefficient) of membranes were determined and discussed. Transport in thermopervaporation increases with an increase of feed temperature (at constant temperature of permeate). During TPV experiments performed with Pervatech in contact with acetone–water system, permeance of acetone increased from 0.12 mol m −2 h −1 kPa −1 at T f = 30 °C to 0.24 mol m −2 h −1 kPa −1 at T f = 42 °C, whereas permeance of butanol increased from 0.45 mol m −2 h −1 kPa −1 at T f = 30 °C to 0.64 mol m −2 h −1 kPa −1 at T f = 41 °C. Pervap 4060 membrane showed better properties in thermopervaporative recovery of butanol and ethanol from water than Pervatech membrane. It was also found that the application of stainless steel porous support reduces ethanol and water fluxes, but it does not affect the selectivity up to 3 wt.% of ethanol in feed.