This book is a state-of-the-art summary of rapidly growing membrane separation technologies including reverse osmosis, ultrafiltration, microfiltration, pervaporation, membrane vapor separation, electromembrane processes, liquid membrane, membrane bioseparation, food applications, membrane contactor, membrane gas separation, and catalytic membrane reactor. The contributors are well selected among

Zwitterionic functional groups possess the greatest polarity found within the nonionic class of hydrophilic groups. Their nomenclature, common misconceptions as to their classification and properties, and their ion exchange and acid-base reactions are discussed. The hydrophilicity of zwitterionic compounds is strongly influenced by the structure and basicity of the anionic substituent group, and to a lesser degree by the length of the ion bridge that binds together these oppositely charged substituent groups. Methylene groups within the ion bridge contribute to the lipophilicity of the molecules, but to a lesser degree than do methylene groups within the long chain.

Electrowetting devices often utilize aqueous solutions with ionic surfactants and inorganic salts to modify the electrowetting response. It has been observed in low-voltage electrowetting devices (thin dielectric, <12 V) that a frequent onset of dielectric failure (electrolysis) occurs with use of ionic solutes such as potassium chloride (KCl) or sodium dodecyl sulfate. More detailed current-voltage investigations reveal less dielectric failure for the larger size ions. Specifically, improved resistance to failure is seen for surfactant ions carrying a long alkane chain. Therefore, a catanionic surfactant (in which both ions are amphiphilic) was custom synthesized, and elimination of dielectric failure was observed in both negative and positive voltage. Because water is a small molecule that easily penetrates dielectrics, further experiments were performed to show that dielectric failure can also be eliminated by use of larger size polar molecules such as propylene glycol. In addition to these results, important parameters such as conductivity and interfacial tensions are reported.

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Surface tension and conductance measurements on tetradecylpyridinium nitrate and hexadecylpyridinium bromide and diffusive interfacial transport experiments on dihexadecyldimethylammonium acetate in 3-methylsydnone are reported. 3-Methylsydnone is aprotic, possesses a high dielectric constant (144 at 40 °C), and has a high cohesive energy density. Unlike hydrogen-bonding solvents of comparable polarity, no evidence for association colloid behavior is detected in 3-methylsydnone. These results confirm previous inferences that hydrogen bonding is a prerequisite for amphiphilic self-assembly.