Separation of Liquid Organic Mixtures by Diffusional Permeation Through Non-porous Polymer Membranes

The physicochemical aspects of a new method of separation of organic liquids by diffusional permeation through non-porous polymer membranes are discussed. The process is assumed to consist of 5 successive steps: transport of material from the liquid to the membrane surface, sorption by the surface layer of the membrane, diffusion through the membrane, desorption from the opposite side of the membrane, and evaporation of the desorbed molecules into the gas (or vapour) phase. The influence of the polymer structure (polyethylene, polypropylene) on the separation process is discussed, and possible modifications of the membrane by solvent treatment, unidirectional mechanical stress, cross-linking by radiation-chemical and photochemical methods, and grafting of other polymers are considered. The effects of the composition of the initial mixture, of the nature of the compounds to be separated, and of temperature are also discussed.
The bibliography includes 85 references.