CONCENTRATION POLARIZATION DURING THE ENRICHMENT OF AROMA COMPOUNDS FROM A WATER SOLUTION BY PERVAPORATION

Pervaporation has proved to be an interesting technique for the recove ry and enrichment of aroma compounds from very dilute solutions. In or der to study the mass transfer, a 0.5-ppm solution of butyl butyrate, an important aroma compound present in, for example, apple juice, was pervaporated at different circulation velocities along a PDMS (polydim ethylsiloxane) membrane. The permeation of butyl butyrate increased wi th increasing Reynolds number, demonstrating an influence of concentra tion polarization. In order to minimize the effect of the polarized la yer and to improve the mass transfer, optimization of the feed-circula tion velocity is very important.