ABSTRACT
Nomenclature ........................................................................................................................................................................... 131 Greek Letters .................................................................................................................................................................. 132 Abbreviations ................................................................................................................................................................. 132
Acknowledgment ..................................................................................................................................................................... 133 References ................................................................................................................................................................................ 133
The contributions of separation to human society cannot be underestimated. Different types of chemicals meet various requirements in our daily life. Most of these are synthetics manufactured by different techniques. These chemicals are an essential part of our life and it is impossible to imagine a civilized society devoid of them. These chemicals range from foods, medicinal drugs, and colorful dyes of our clothes to detergents for washing and cleaning of every essential commodity. There is very little doubt that much of these activities involved in the manufacture of the synthetics are causing certain damage to the delicate balance in the ecosystem. Developments in ‘‘Green’’ technologies are not just academic curiosities but are increasingly finding commercial applications. The widespread use of the natural resources has led to depletion of natural, nonrenewable energy sources. There is an ever-increasing awareness about optimum utilization of the nonrenewable sources (NRS). One major mode of consumption of NRS in the chemical process industries (CPI) is the use of fossil fuels as a source of
processes of the CPI. Amongst the various separation processes used in the CPI, the major consumption of fuels in the CPI occurs in distillation. It is impossible to build a chemical plant without using distillation at some point in the process. Even isolation of natural products such as essential oils, spices, photochemical, etc. cannot be accomplished without resorting to distillation. Distillation as commonly employed uses a high grade heat in the reboiler and rejects the same as very low-grade heat in the condenser. With the awareness about optimum and efficient utilization of these NR fuels, the CPI is looking at alternatives to this highly energy intensive operation. Thus, membrane separations that either do not involve a phase change or use low-grade heat for the phase change during separation are becoming significantly important as an alternative to distillation. Several new, promising approaches have been made recently. A large number of separation processes are available for separation of components from a mixture. Amongst these the membrane-based separation techniques include microfiltration, ultrafiltration, nanofiltration, reverse osmosis, and pervaporation (PV). Pervaporation in which permeation through a dense membrane is followed by evaporation is the subject of this chapter.
