Green extraction of perilla volatile organic compounds by pervaporation

Volatile organic compounds (VOCs) present in perilla essential oil are of high interest in medicinal and food processing. In this work, pervaporation was implemented to extract the valuable perilla VOCs from dilute aqueous solutions as a green process. Three representative VOCs of perilla (i.e., limonene, linalool, and perillaldehyde) having different functional groups were selected as model components, and poly(ether-block-amide) (PEBA) and polydimethylsiloxane (PDMS) membranes were prepared for the VOC extraction studies. The influences of operating conditions (i.e., feed concentration and temperature) on the pervaporation performance of the membranes were investigated. In binary VOC/water mixtures, an increase in the feed concentration increased the VOC flux and decreased the separation factor. The VOC flux also increased significantly with temperature, mainly due to an augmented driving force for permeation. The impact of the coupling effects in multicomponent permeation was evaluated by comparing the pervaporation performance of VOCs in binary VOC/water and quaternary VOCs/water systems. Results show that the VOC permeation behavior was affected by the presence of other VOCs, depending on the permeant-permeant and membrane-permeant interactions. Based on pervaporation separation index, the PEBA membrane showed a better overall separation efficiency than the PDMS membrane for the extraction of perilla VOCs. Since pervaporation does not involve any chemical solvents and operates at moderate temperatures, it provides a green process for extracting valuable perilla VOCs.