Electrodeposition Electrophoresis

Most chemical techniques can be applied in the processing precipitation, ion exchange, solvent extraction, electrodeposition, electrophoresis, distillation, etc. The basic purposes are to eliminate radioactive contaminants and to avoid diluting the radionuclide by isotopic stable atoms. If the radionuclide or radiochemical is to be used in medical and biological work, the sample may have to be sterile. Some publications about radiochemical separation procedures are given in the literature list, 15.9. 

Precipitation Electrodeposition Masking Ion Exchange Filtration Centrifugation Exclusion Chromatography Dialysis GLC, GSC, LLC, LSC Liquid-Liquid Extraction Distillation Sublimation Zone Electrophoresis Zone Refining ... 

The modem process of electrodeposition can thus be described as a combination of three basic elements (a) Electrophoresis - migration of charged polymer particles to metal surface (b) Deposition - colloidal de-stabilization of particles at the metal-bath interface and (c) Insulation - formation of an adherent, non-conductive layer of resin on the metal surface. The last named element is responsible for the high throwing power which can be achieved with the electrocoating process. 

Electrophoretic Deposition (EPD) is a forming process where charged particles are consolidated on a substrate in a DC electric field (14). This field causes the particles to move, and deposit on, the oppositely charged electrode (Figure 9.9). EPD is a combination of two processes, i.e. electrophoresis and deposition. Electrophoresis controls the motion of the charged particles in the electric field while the deposition mechanisms control the buildup of the dense particle layer on the electrode. EPD should not be confused with electrodeposition, where ions are deposited and discharged at the electrode. 

Separation procedures are based on the principles of volatilization, liquid-liquid distribution, adsorption, diffusion, chromatography, ion exchange, electrophoresis, precipitation, coprecipitation, and electrodeposition. In all of these, radio-tracers provide the best tool for methodological investigations, determination of equilibrium constants, kinetic data, and optimization of applied analytical data (yield, interference levels, etc.) [54], Use of radiotracers in complex multielement separation schemes is reviewed in [4], [17], [20]. [41], [54], radiochromatography is reviewed in [551. [61], [93], 197],... 

Many properties of electrolyte solutions (e.g., electric conductance, ohmic losses, and power capability of a battery electrophoresis and polar-ography polarization and depolarization of electric double layers electroplating and electrodeposition) depend directly or indirectly on the ion mobility of its constituents. This entry deals with the ion mobility in aqueous and nrmaqueous solutions. For other systems, the reader is referred to monographs of, e.g., J. Maier [1] for solids or of K. Kontturi et al. [2] for membranes or electrodes. 

The principle of electrophoresis, the most straightforward method for electrodeposition is based on the electric field-driven charged particles (silicate, organosilicate, metal oxides, micelles, or polymer composite particles) to an electrode at an electrophoretic velocity, v, which is determined by Stoke s law. 

The amine moieties, which were oriented toward the gold surface, could not get protonated and thus the capped nanoparticles were more negatively charged as compared to the aminosilane moieties that enhanced their electrophoresis. Another important mechanism that facilitated gold electrodeposition was anodic oxidation of the gold nanoparticle surface, which ranoved the gold capping and thus increased its tendency to participate in film formation. 

Electrodeposition, also called electrocoating, is a process by which organic materials are coated from aqueous suspension, or solution, onto a conductive substrate under the influence of electricity. The process utilizes direct current for depositing resins, so that predominantly electrophoretic processes operate. Electrophoresis in this context is understood to mean the migration of colloidal or suspended particles in an electric field. The particles migrate, according to their charge, to the anode (anaphoresis) or to the cathode (cataphoresis). 

Although the principle of electrophoresis has been known since 1809, from the work of Reuss, it has remained confined to a very few areas of application in medical, analytical and other technological fields. The process of electrophoretically depositing paints and lacquers could only be applied industrially when new ionizable paints and resins were developed that could be diluted with water and deposited from an aqueous medium under the influence of an electric current, similarly to the electrodeposition of metals (although the electrodeposition of organic material is much more complex). It was not possible to electrodeposit conventional organic-based paints, since these did not form ions, and known water-soluble paints that could be applied by conventional immersion or spraying techniques were too expensive. 

Electrophoresis is applied among other things in the process of electrodeposition (chapter V, 10, p 234), in which colloidal particles (often in an organic medium) are drawn by. an electric field to one of the electrodes and, under suitable conditions, form a firmly adhering and homogeneous deposit on it ... 

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