| The dissolution behavior of nickel in iodine/iodide solutions was investigated using a rotating disc. Experimental variables studied here included pH of the solution, temperature, concentration of lixiviants, and rotating speed of the nickel disc. Nickel easily dissolved when pH of the solution was about 2. However, the dissolution rate dramatically decreased when the pH of the solution became greater than 3. The dissolution rate increased at faster rotating speed, higher initial concentration of iodine, and temperature of the solution. The overall dissolution reaction rate was found to be influenced partially by surface chemical reaction and largely by mass transfer of triiodide through diffusion boundary layer at the liquid/solid interface with an activation energy value of 17.2 kJ/㏖. The possibility of reutilization of used iodine/iodide solution by electrowinning in an electrochemical cell was investigated and the results were promising. |
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