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J ELECTROCHEMICAL OXIDATION 275 The H+ ions created in the process migrate to the cathode possibly to form H 2 gas; the Ag+ ions are reoxidized at the anode to Ag2+. In principle the only products of a hydrocarbon oxidation will be CO2 and H2. Heteroatoms in organic compounds are also oxidized: sulfur to sulfate, phosphorus to phosphate, nitrogen atoms to molecular nitrogen or N-oxides, chlorine to molecular chlorine, and fluorine to fluoride and molecular fluorine. Gaseous products (CO2, N2, NO, Cl2) are withdrawn; the other materials remain in the electrolyte and must be recovered from the solution. The two components of the process, electrolysis and chemical reaction, may be combined in one vessel or separated into two. That is, the organic may be added directly to the oxidizing fluid of the anode compartment. Alternatively, the oxidizing anode fluid may be pumped to a separate vessel to contact the organic material to be destroyed. STATUS AND DATABASE The electrolytic cells required are well developed. The cell size required (e.g., area of anode) would be large but in the range of industrial experience. There has been a substantial research effort on electrolytic decontamination processes, generally for small flow rates as for air purification. Various mediating ion couples have been used: cerium (HI/IV), iron (II/III), or chromium (III/VI). The AEA Technology process using silver as the mediating ion has been developed to at least pilot plant scale of a few hundred pounds per day. It has been used to oxidize uranium during separations processing of plutonium from uranium. It has been tested at small scale for the destruction of solvents. The metal ions differ in their reactivity and ability to oxidize. Silver is very reactive at moderate temperature (less than 100°C). It has been used with nitric acid (10 percent by weight) as the electrolyte. The primary cathode reaction is then reduction of nitrate ion instead of H2 production: This has the advantage of reducing the voltage required (reducing power); but it has the disadvantage of an additional chemical step to reoxidize the nitrous acid or recover NOx in the cathode gas. Other metal ions are less reactive; they require a longer time to complete the oxidation or higher temperature. An experimental process using iron, for example, is reported to operate at 180°C; the vessel pressure would have to exceed 10 bars to prevent boiling.