Abstract
Bio-derived solvents such as rho-cymene, d-limonene and alpha-pinene represent feasible alternatives to n-hexane for the extraction of vegetable oils. However, the large-scale utilization of these solvents is still limited mainly owing to their high boiling points and latent heats of vaporization. In this work, the performance of composite polydimethylsiloxane/polyacrylonitrile (PDMS/PAN) organic solvent nanofiltration membranes in the recovery of these solvents from their binary mixtures with canola oil is investigated. The sorption isotherms of the mixtures were first studied using free-standing PDMS films and the multicomponent Flory-Huggins model used to determine the resulting interaction parameters. The partial solvent uptake decreased with increasing oil concentration in the mixture. On the other hand, the partial oil uptake in the solvent mixture was higher than that of the pure oil which was attributed to the swelling effects induced by solvents. The effects of feed concentration (10-30 wt% oil), feed temperature (25-40 degrees C), transmembrane pressure (5-30 bar), and cross-flow velocity (18-52 cm s(-1)) on the membrane performance were then studied in a cross-flow membrane setup. Maxwell-Stefan formulations were combined with the ternary Flory-Huggins solubility model to successfully describe these flux data.