Separating multicomponent water-alcohol mixtures in a spiral membrane plant

There have been advances in the chemical, petrochemical, and other branches of industry because of efficient, economical, and ecologically clean methods of separating mixtures. In heavy organic synthesis processes, it is often necessary to separate mixtures of substances similar in boiling point that are azeotropic or not thermally stable. When one uses solvent extraction or azeotropic rectification, one requires large-scale and ecologically hazardous equipment, whose cost may be up to 50% of the cost of the entire process. These problems may be resolved with the latest membrane technologies, amongst which there is evaporation through a membrane (pervaporation), which has a special place. Calculations and accumulated evidence show that semipermeable membranes provide a considerable saving in traditional processes, with good scope for essentially new, simple, low-energy, and socially justified technological schemes (particularly in combination with the common separation methods such as distillation, adsorption, and solvent extraction), which can improve the product quality and serve to utilize secondary raw materials and wastes. Membrane methods are also used in treating water and aqueous solutions and in purifying effluents.