Performance of PVA- and zeolite-membranes in selective drying processes

Selective drying of a product is desired if certain compounds like aroma are to be retained in the product and certain other compounds like for instance water are to be removed. This task may be achieved by a combination of vacuum contact drying and selective membrane permeation of the vapour. Crucial for the economy of such process is the performance of the permeation membrane. Comparative experimental results on the performance of hydophilic membranes for the permeation of water and the retention of organic molecules (iso-propanol and others) are presented. The obtained data prove the superior performance and economics of NaA-Zeolite-membranes in comparison to conventional Poly-Vinyl-Actetate (PVA) membranes.