The Interface Structure and Electrochemical Processes at the Boundary Between Two Immiscible Liquids

Studies on the electrochemical processes at the interface between two immiscible liquids began a long time ago: they date back to the end of the last century. Such celebrated scientists as Nemst and Haber, and also young A. N. Frumkin were among those who originated this science. Later A. N. Frumkin went a long way in furthering the studies at the Institute of Electrochemistry. The theory of the appearance of potential in a system of two immiscible electrolytes was developed and experimentally verified before the beginning of the thirties. In later years the studies in this area considerably lagged behind those conducted at metal electrodes which were widely used in different industries. In the past 15 years, however, the situation has radically changed and we have witnessed a drastic increase in the number of publications on the electrochemistry of immiscible electrolytes. We are glad to note that the investiga­ tions show not only a quantitative but also a qualitative change. The theoretical works on the oil/water interface test not only the thermodynamic aspects of the inter­ face but also recreate the molecular picture of the process. Along with the now con­ ventional oilfwater system, electrochemical studies are made on various membranes, including the frnest bilayer lipid membranes, and also on microemulsion systems. A prominent place in the investigation of the oil/water interface is occupied by photoprocesses that come into play at the interface between two ionic conductors.

Electrolysis at the Interface Between Two Immiscible Electrolyte Solutions.- Theory.- Experimental Procedures.- Results and Applications.- References.- Problems of a Quantum Theory of Charge Transfer Reactions at the Interface Between Two Immiscible Liquids.- 1. The Franck-Condon Principle and the Physical Mechanism of the Transition.- 2. The Role of a Polar Medium and the Solvent Model.- 3. The Reorganization Energy of the Medium.- 4. The Role of Intramolecular Vibrations and Quantum Degrees of Freedom.- 5. General Regularities in Charge Transfer Processes at the Interface Between Immiscible Liquids.- 6. Electron Transfer at the Interface of Two Immiscible Liquids.- 7. Ion Transfer Through the Interface.- 8. Conclusion.- References.- Hydrodynamics and Mass Exchange at the Phase Boundaries with Regular Dissipative Structures.- 1. Introduction.- 2. General Theoretical Description of Dissipative Structures.- 3. Capillary Instability Due to the Marangoni Effect.- 4. Electro-hydrodynamic Instability.- 5. The Linear Analysis of Marangoni Instability.- 6. The Instability Caused by the Electric Forces Acting at the Surface of an Electrolyte Solution.- 7. Nonlinear Methods of Analyzing the Marangoni Instability.- 8. Models of Systems with Regular Hydrodynamic Dissipative Structures.- 9. Regular Circulation Fluxes Caused by Hydrodynamic Instability and their Role in Interfacial Mass Exchange.- 10. Conclusion.- References.- Galvani and Volta Potentials at the Interface Separating Immiscible Electrolyte Solutions.- Abstract.- 1. Introduction.- 2. Liquid Galvanic Cells ― a Historical Survey.- 2.1 Investigations of the Nernst Type Cells.- 2.2 Investigations of the Haber Type Cells.- 2.3 Other Types of Liquid Cells.- 3. Galvani Potential at the Interface of Immiscible Electrolyte Solutions.- 3.1 General Approach of Le Hung.- 3.2 Distribution Potentials for Binary Electrolytes.- 3.3 Interfaces Reversible with Respect to Single Ions.- 3.4 Experimental Investigations of Galvani Potentials of Nonpolarizable Interfaces.- 3.5 Ion Transfer Energies and Galvani Potentials.- 4. Polarizable Interface of Inamisible Electrolyte Solutions.- 5. Volta Potentials at the Interfaces of Immiscible Electrolyte Solutions.- 6. Final Observations.- References.- Electrocapillarity and the Electric Double Layer Structure at Oil/Water Interfaces.- Summary.- Ideal-Polarized and Nonpolarized Oil/Water Interfaces.- Electrocapillary Curves of Ideal-Polarized Oil/Water Interfaces.- Electrocapillary Curves of Nonpolarized Oil/Water Interfaces.- References.- Study of the Electrical Double Layer at the Interface Between Two Immiscible Electrolyte Solutions by Impedance Measurements.- Thermodynamic Background.- AC Impedance Measurements.- Galvanostatic Pulse Technique.- Capacitance Data.- Zero-Charge Potential Difference.- Inner-Layer Potential Difference and Capacitance.- References.- Redox and Photochemical Reactions at the Interface Between Immiscible Liquids.- I. Introduction.- II. Redox Reactions in Monolayers.- III. Redox Processes in the Oil/Water System when Donor and Acceptor are Contained in Different Phases.- 1. Evidence for the Occurrence of the Process.- 2. Influence of Specific Adsorption of Halogen Ions on the Reduction of Hydrophobic Porphyrin.- IV. Metalcomplexes of Porphyrins ― Catalysts of Redox Reactions at the Interface Between Immiscible Liquids.- 1. Redox Reactions Involving Chlorophyll.- 2. Adsorption of Chlorophyll at the Oil/Water Interface.- 3. Redox Reactions Catalyzed by Chlorophyll in the Oil/Water System.- 4. Formation of the Boundary Layer Enriched in Protons.- 5. Redox Reactions Catalyzed by Other Metalloporphyrins.- V. Evidence for the Heterogeneity of Redox Reactions Catalyzed by Metalcomplexes of Porphyrins.- 1. Adsorption of Catalyst at the Interface.- 2. Cause of the Potential Shift and its Proportionality to the Concentration of Adsorbed Catalyst.- VI. Enzyme Complexes of the Mitochondrial Respiratory Chain in the Oil/Water Interface.- VII. Redox Reactions in the Oil/Water System Accompanied by Protonation of Acceptor in the Nonaqueous Phase.- 1. Enzyme-Catalyzed Redox Reactions Accompanied by Capture of Proton by Acceptor in the Nonaqueous Phase.- 2. Chlorophyll-Catalyzed Redox Reaction Accompanied by the Capture of Proton Acceptor in the Nonaqueous Phase.- 3. Photooxidation of Water Catalyzed by Chlorophyll Adsorbed at the Interface Between Two Immiscible Liquids.- 4. Carotene ― a Photosensitizer of the Water Photooxidation Reaction.- 5. Possible Mechanism of Water Photooxidation Sensitized by Chlorophyll.- 6. Reaction Thermodynamics.- VIII. Coupling of Reactions at the Interface Between Immiscible Liquids.- References.- Counterions and Adsorption of Ion-Exchange Extractants at the Water/Oil Interface.- Abstract.- The Water/Oil Interface and Extraction Processes.- Adsorption and Extraction Constants.- Counterions and Adsorption of Extractants.- 1. Alkylammonium Salts.- 2. Cation-Exchange Extractants.- 3. Macrocyclic Ionophores.- Determination of Activity Coefficients for Extractants in Low-Permittivity Media from Surface Pressure Isotherms.- References.- Kinetics of the Photochemical Charge Separation in Micellar Solutions.- 1. The Formal Kinetics of Reactions in Micellar Systems.- 1.1 Solubilization of Molecules by Surfactant Micelles and the Distribution of Reactant Molecules Among Micelles.- 1.1.1 The Pseudophase and Microscopic Models of Solubilization.- 1.1.2 Solubilization as a Kind of Interphase Equilibrium.- 1.1.3 The Effect of the Intermicellar Distribution of Reactant Molecules.- 1.2 The Interfacial Exchange of Molecules in Microheterogeneous Solutions.- 1.2.1 The Exchange of Molecules at the Interface Between Micelles and Bulk Phase.- 1.2.2 First-Order Reaction in Micellar Solutions.- 1.2.3 Second-Order Photoreactions in Micellar Solutions. CMC Measurements and Aggregation Numbers.- 1.2.4 Reversible Reactions.- 2. Charge Separation in Micellar Systems.- 2.1 Micelles as Media for Photochemical Reactions.- 2.1.1 Models of Micellar Solutions Influencing the Reactivity of the Solubilizates.- 2.1.2 The Effective Microviscosity and Polarity of Micelles.- 2.2 Initial Charge Separation and Geminate Recombination in Micellar Systems.- 2.2.1 Photoionization in Micellar Solutions.- 2.2.2 Photoprotolytic Dissociation in Micellar Solutions.- 2.2.3 Second-Order Intramicellar Electron Transfer Reactions.- 2.2.4 Bimolecular Proton Transfer Reactions.- 2.3 Initial Stabilization of the Charge Separation Products.- 2.4 Bulk Recombination of Separated Charges and Mass Exchange at the Interface.- 2.4.1 Effect of the Micellar Potential upon the Bulk Recombination of Charge Carriers.- 2.4.2 Effect of the Hydrophobic Balance of Reactants upon their Solubilization.- 2.4.3 Molecule Exchange at the Interface.- 2.5 Stabilization of the Separated Charges in Systems with Mediators.- 3. Conclusion.- References.