ABSTRACT
Separation processes based on membrane utilize semipermeable membranes of the appropriate physical and chemical nature to separate molecules primarily on the basis of size and to a lesser extent on shape and chemical composition [1]. In these processes, the membrane acts as a selective barrier, enriching certain components in a feed stream and depleting it of others. Reid and Breton [2] who used cellulose acetate membranes for desalination of water made the first real breakthrough. Shortly thereafter, Loeb and Sourirajan [3,4] developed the casting procedure for asymmetric cellulose acetate membranes. The most attractive feature of the process is its simplicity. It involves only bulk movement of fluids using mechanical energy (i.e., pumping). Membrane concentration processes have several advantages over conventional concentration processes, i.e., evaporation. Undesirable heat-related changes such as color, aroma, and viscosity characteristics are avoided because membrane processes can be operated at room temperature. Unlike evaporation or freeze concentration, membrane separation does not involve a phase change for separation; thereby energy is used more efficiently.
