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.
Gorri et al. (Tue,) studied this question.