Experimental and Modeling Study of Ethylene Glycol-Water Mixture Dehydration by Pervaporation for Coolant Liquid...

The dehydration of ethylene glycol-water mixtures is a relevant challenge in the recovery and reuse of cooling liquids from industrial processes, particularly in the pharmaceutical sector. This work investigates the feasibility of using pervaporation with a hydrophilic polymeric membrane (PERVAP 4101, based on highly cross-linked poly-(vinyl alcohol)) to partially dehydrate mixtures containing up to 70 wt% water and maintain compositions close to the eutectic point (≈58 wt% ethylene glycol). Experimental tests were conducted in a laboratory-scale pervaporation unit at 60, 70, and 80 °C. The influence of feed composition and temperature on permeation flux, separation factor, and long-term stability was analyzed. A conditioning stage at 80 °C was found to be essential to achieve steady operation, resulting in high water selectivity (98.9-99.8 wt% water in permeate) and stable fluxes up to 4.2 kg m^-2 h^-1 during 30 h continuous tests. ATR-FTIR spectra of the pristine and conditioned membranes revealed only minor structural modifications, suggesting a slight reduction in crystallinity associated with increased permeability, which was later confirmed by DSC analysis. The experimental data were successfully correlated using a solution-diffusion model, considering the dependence of permeance on component activity and temperature. The apparent activation energies for water and ethylene glycol permeation were 34-42 and 43-58 kJ mol^-1, respectively. Results confirm that PERVAP 4101 membranes provide an efficient and stable route for ethylene glycol dehydration at high water contents, demonstrating potential for industrial implementation.