Separation of ethylene glycol solution by vacuum membrane distillation (VMD)

The feasibility of VMD for concentration of ethylene glycol (EG) from a used coolant liquid is presented. VMD experiments were performed with water-EG mixtures using a flat-sheet polypropylene membrane at various temperatures and recirculation rates. Results show that the membrane almost completely rejects EG and the desired concentration was achieved. This is due to the vapor pressure of EG being negligible compared to that of water. Increasing temperature and recirculation rate increased flux with no effect on EG rejection. Increasing of feed flow rate higher than 0.67 had no strong effect on permeate flux.