Bøger i Plenum Chemical Engineering serien

The present book contains a comparison of existing theoretical models developed in order to describe membrane separation processes. In general, the permeation equations resulting from these models give inaccurate predictions of the mutual effects of the permeants involved, due to the simplifications adopted in their derivation. It is concluded that an optimum description of transport phenomena in tight (diffusion-type) membranes is achieved with the "solution-diffusion" model. According to this model each component of a fluid mixture to be separated dissolves in the membrane and passes through by diffusion in response to its gradient in the chemical potential. A modified Flory-Huggins equation has been derived to calculate the solubility of the permeants in the membrane material. Contrary to the original Flory-Huggins equation, the modified equation accounts for the large effect on solubility of crystallinity and elastic strain of the polymer chains by swelling. The equilibrium sorption of liquids computed with this equation was found to be in good agreement with experimental results. Also, the sorption of gases in both rubbery and glassy polymers could be described quan­ titatively with the modified Flory-Huggins equation without any need of the arbitrary Langmuir term, as required in the conventional "dual-mode" sorption model. Furthermore, fewer parameters are required than with the at least identical accuracy.

I. Electron Transfer Reactions.- 1. Electron Transfer: General and Theoretical.- 1.1. Overview and General Aspects of Reactions in Fluid Media.- 1.2. Electronic Coupling (Ke1).- 1.2.1. The Distance Dependence of Electron Transfer Rates.- 1.2.2. Electric and Magnetic Field Effects on Electronic Coupling and Related Problems of Photoinduced Electron Transfer.- 1.3. The Free-Energy Dependence of Electron Transfer Reactions: The "Inverted Region" Problem.- 1.4. The Effects of Solvent Dynamics.- 1.5. Metal-to-Metal and Ligand-to-Ligand Charge Transfer ("Inter-valence" Transfer).- 2. Redox Reactions between Two Metal Complexes.- 2.1. Introduction.- 2.2. Reactions of Metal Aqua and Oxo Ions.- 2.2.1. Titanium.- 2.2.2. Vanadium and Chromium.- 2.2.3. Iron.- 2.2.4. Molybdenum and Tungsten.- 2.3. Reactions of Metal Ion Complexes.- 2.3.1. Chromium.- 2.3.2. Manganese.- 2.3.3. Iron, Ruthenium, and Osmium.- 2.3.4. Cobalt and Rhodium.- 2.3.5. Nickel, Palladium, and Platinum.- 2.3.6. Copper and Silver.- 2.3.7. Technetium and Rhenium.- 2.3.8. Ytterbium.- 2.4. Reactions with Metalloproteins.- 2.4.1. Introduction.- 2.4.2. Copper Proteins.- 2.4.3. Hemoglobin and Myoglobin.- 2.4.4. Cytochromes.- 2.4.5. Iron-Sulfur Proteins.- 3. Metal-Ligand Redox Reactions.- 3.1. Introduction.- 3.2. Oxygen, Peroxide, and Other Oxygen Compounds.- 3.2.1. Dioxygen.- 3.2.2. Hydrogen Peroxide.- 3.2.3. Alkyl Hydroperoxides.- 3.3. Nitrogen Compounds and Oxyanions.- 3.3.1. Hydrazine, Azides, Hydroxylamines, and Derivatives.- 3.3.2. Oxynitrogen Compounds.- 3.3.3. Amines and Nitriles.- 3.4. Sulfur Compounds and Oxyanions.- 3.4.1. Peroxodisulfate and Peroxomonosulfate.- 3.4.2. Sulfur Dioxide and Sulfite Ions.- 3.4.3. Sulfoxides.- 3.4.4. Alkyl Sulfur Compounds.- 3.4.5. Selenium, Tellurium, and Elemental Sulfur.- 3.5. Halogen, Halides, and Halogen Oxyanions.- 3.5.1. Halogens.- 3.5.2. Halides.- 3.5.3. Oxyhalogen Compounds.- 3.6. Phosphorus, Arsenic, and Oxycompounds.- 3.6.1. Phosphorus Oxyanions.- 3.6.2. Phosphines and Arsines.- 3.7. Inorganic Radicals.- 3.8. Ascorbic Acid, Quinols, Catechols, and Diols.- 3.8.1. Ascorbic Acid.- 3.8.2. Aromatic Diols and Diones.- 3.8.3. Aromatic and Aliphatic Alcohols.- 3.9. Carboxylic Acids, Carboxylates, Carbon Dioxide, and Carbon Monoxide.- 3.9.1. Carboxylic Acids and Carboxylates.- 3.9.2. Carbon Dioxide and Carbon Monoxide.- 3.10. Alkyl Halides.- 3.11. Organic Radicals.- II. Substitution and Related Reactions.- 4. Reactions of Compounds of the Nonmetallic Elements.- 4.1. Boron.- 4.2. Carbon.- 4.3. Silicon.- 4.4. Germanium.- 4.5. Nitrogen.- 4.6. Phosphorus.- 4.7. Arsenic.- 4.8. Oxygen.- 4.9. Sulfur.- 4.10. Selenium and Tellurium.- 4.11. Halogens, Krypton, and Xenon.- 4.11.1. Fluorine.- 4.11.2. Chlorine.- 4.11.3. Bromine.- 4.11.4. Iodine.- 4.11.5. Krypton and Xenon.- 4.12. Oscillating Reactions.- 5. Substitution Reactions of Inert-Metal Complexes-Coordination Numbers 4 and 5.- 5.1. Introduction.- 5.2. Associative Ligand Exchange at Square-Planar Platinum(II).- 5.3. Associative Ligand Exchange at Square-Planar Palladium(II).- 5.4. Ligand Exchange at Platinum(II) by Dissociative Processes.- 5.5. Ligand Exchange at Nickel.- 5.6. Reactions of Planar Ir(I), Rh(I), Au(III), and Cu(II) Complexes.- 5.7. Five-Coordinate Species.- 5.8.TransEffect.- 5.9. Isomerizations.- 6. Substitution Reactions of Inert-Metal Complexes-Coordination Numbers 6 and Above: Chromium.- 6.1. Introduction.- 6.2. Aquation and Solvolysis of Chromium(III) Complexes.- 6.2.1. [Cr(III)(L5)X]n+1Systems (L = OH2, NH3).- 6.2.2. Cr(III)-C Bond Rupture.- 6.2.3. Amine and Other Complexes.- 6.2.4. Dechelation/Chelation Processes.- 6.2.5. Metal-Ion-Assisted Aquation.- 6.2.6. Porphyrins.- 6.3. Formation of Chromium(III) Complexes.- 6.3.1. The Nature of the Cr3+Cation in Aqueous Solution.- 6.3.2. Anation Reactions.- 6.4. Base Hydrolysis.- 6.5. Oxidation and Reduction of Cr(III) Complexes.- 6.6. Isomerization and Racemization.- 6.7. Photochemistry and Photophysics of Chromium(III) Complexes.-...