Evaluating membrane behavior to ethanol-water mixtures and wine: a comparative investigation

In this study the performance of three nanofiltration membranes (TS 40, NF99, HL) and one reverse osmosis membrane (RO-SE) while filtering ethanol-water mixtures (0 – 10.5% v/v) and a white wine (10.5% v/v) was evaluated. The experiments were conducted using water, ethanol-water mixtures, and white wine at varying pressure (0 – 20 bar, 21 ± 1 ◦ C) to explore the impact of pressure on permeate flux and permeability. Further tests were performed with white wine and ethanol-water mixture (10.5% v/v) at pressure 20 bar and 21 ± 1 ◦ C up to volume reduction factor of 4 to evaluate performance (based on permeate flux, permeability, fouling index, ethanol rejection and retention of selected compounds) of different membrane. Among the investigated mem- branes the HL membrane exhibited the highest permeate flux consistently across varying operational pressures, showcasing superior permeability. HL and NF99 membranes showed greater effectiveness in reducing the alcohol content in wine, with ethanol rejection rates of 5.14% and 5.46%, respectively. Conversely, RO-SE (10.64%) and TS 40 (18.30%) exhibited the highest ethanol rejection rate. The fouling index for all the membranes ranged between 22.5 and 43.5%. In addition to this NF and HL also showed highest rejection towards reducing sugars (> 90%), glucose (> 80%), fructose (> 88%), citric acid (> 88%) and tartaric acid (> 89%) in dealcoholized wine. Overall, HL and NF99 membranes appear to be the most effective options for wine dealcoholization.