2004 年 37 巻 1 号 p. 82-88
Esters of volatile organic flavor compounds were recovered from dilute aqueous solutions by pervaporation; ethyl acetate (EA), propyl acetate (PA), and butyl acetate (BA). A surface-modified tube-type alumina membrane was used to evaluate the effects of the feed concentration (0.15–0.60 wt%) and feed temperature (30–50°C) on the separation of EA, PA, and BA from dilute aqueous solutions. The permeation flux increased with the increasing feed ester concentration and operating temperature. The separation factors for the 0.15–0.60 wt% feed solutions of EA, PA, and BA at 40°C were in the range of 66.9–78.9, 86.0–89.0, and 117.1–94.7, respectively. EA, PA, BA in the permeate were concentrated up to 9.13–32.26, 11.44–34.95, and 14.96–36.37 wt%, respectively. Due to the high selectivity, phase separation occurred in the permeate stream because the ester concentration in the permeate was above the saturation limit. The fluxes of EA, PA, and BA at 0.60 wt% feed concentration and 40°C were 254, 296, and 318 g/m2·h, which are much higher than those obtained with polymer membranes. In the case of PDMS at feed concentrations of 90–4800 pp, and at 45°C, it was reported that the permeate flux of EA was 1.1–58 g/m2·h. Compared to PDMS, the surface-modified membrane investigated in this study showed a much higher flux of esters.
