| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 96 === The objective of this research was to develop a technique of recovery of indium from spent ITO on the processing waste and the LCD panels. The process of recovery includes three steps, leaching, separation/purifying, and recovering. First, leaching the spent ITO by 1 M, 2 M and 4 M HCl solution and then adding NaOH and HCl to adjust the pH= 0.79, 0, -0.43, finally recovering indium from the lixivium by potentiostastic electrolysis at -0.8, -0.9, -1.0 and -1.2VSCE.. Investigation of the effect of electrolysis parameters, such as pH value, cation concentration and potential, on the percentage of recovery and the mechanism of reduction will be described in the following content.
According to the experimental results, the percentage of recovery increased with the potential decreased. In the solution with relatively higher pH value, the rate of indium reduction accelerated as the concentration of chloride ions increased. When the electrolyte contained fewer chloride ions, the higher pH value was, the larger percentage of recovery reached. Especially, when applying -1.2 VSCE. in 1 M HCl with pH=-0.43, the percentage of recovery got up to 96 %. As the SEM photographs showed, the particles with small size deposited at more negative potential in the form of cluster. On the contrary, the deposition produced at more positive potential had the shape of leaf-like and grain-like crystal. According to the analysis by EDS, the deposition principally was composed of In, and a small amount of impurities, such as O and Cl. The content of impurities varied with the morphology of deposition.
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