Air gap membrane distillation of MEG solution using PDMS coated polysulfone hollow fiber membrane

Surface modified porous polysulfone (PSF) hollow fiber membrane was prepared by dip-coating of polydimethylsiloxane (PDMS). The prepared membranes were used in an air gap membrane distillation (AGMD) process for dehydration of MEG-water mixtures. The membranes were characterized in terms of Field Emission Scanning Electronic Microscopy (FESEM), N2 permeation, contact angle measurement and wetting pressure. From FESEM images, the prepared membrane showed a porous structure with finger-like cavities. In addition, formation of ultra-thin coating layer on the inner and outer surface was confirmed by FESEM. From N2 permeation test, the modified membrane showed smaller mean pore size (9 nm) and lower surface porosity compared to the plain membrane. The modified membrane showed a good hydrophobicity with water contact angle of 118° and wetting pressure of 800 kPa. The permeate flux of about 26 kg/m2h was obtained for the modified membrane at MEG concentration of 20 wt%, feed temperature of 90 °C and feed velocity of 0.66 m/s. Due to the improved structure, the modified membrane showed a stable AGMD operation for 80 h compared to the plain membrane.