A Study of the Electrochemical Dissolution of Platinum

• Main Authors: C. C. Huang, 黃建智
• Other Authors: J. Y. Hwang
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/60147769733275039313

碩士 === 國立臺北科技大學 === 化學工程系碩士班 === 91 === Chloroplatinic acid is widely used in various fields of engineering and Science. The platinum salts were usually produced by chemical dissolution of platinum metal in aqua regia solutions. However, the high chemical resistance of platinum metal makes the process of dissolution be difficult and time-consuming. Chemical process takes place at high temperatures and the emission of harmful gaseous products. This investigation is to study the effects of concentrations of hydrochloric acid and oxidizing agents, temperature and optimal potential on the anodic dissolution of platinum by electrochemical methods including direct current and superimposed alternating current over direct current. The object of this study is to evaluate the electrochemical dissolution of platinum metal in different concentrations of hydrochloric acids. The contents of this thesis can be divided into three parts. First, the electro-dissolution reaction of platinum in the hydrochloric acid solutions with and without hydrogen peroxide were studied. The best condition of anodic dissolution of platinum in hydrochloric acid solution was obtained. The optimal temperature of the electrolyte is at 60℃. The concentration of hydrochloric acid in electrolyte is 37%. The optimal potential of the dissolution of platinum is 0.656V(vs. SCE). Next, the anodic dissolution of platinum in hydrochloric acid solutions were studied by direct current method. The concentration of platinum in electrolyte was measured by AAS. According to the result of 180min test while the platinum ion concentration is 1130.325ppm, the optimal concentration of hydrogen peroxide in electrolyte is 15%. At last, the anodic dissolution of platinum in hydrochloric acid solutions were studied by superimposing 50Hz sinusoidal, triangular and square waves of alternating current over direct current. The optimal condition of anodic dissolution of platinum in hydrochloric acid solution was obtained. The optimal temperature of the electrolyte is at 70℃. The concentration of hydrochloric acid in electrolyte is 30% and the optimal method is superimposing 50Hz triangular alternating current over direct current. The concentration of platinum in electrolyte was measured by AAS. The optimal concentration of hydrogen peroxide in electrolyte is 10%, which is the result of 180min test while platinum ion concentration is 1084.5ppm. The dissolution rate of platinum with superimposing 50Hz triangular alternating current over direct current can enhance to 2.5 times up than only with direct current. From the Ultraviolet-Visible spectrometry analysis, is shows that the hexachloroplatinic acid complex ion PtCl62- is dominant. Furthermore, the SEM analysis indicates obvious dissolution of platinum. Therefore, it can conclude that the electrochemical dissolution of platinum is an efficient and promising method for the production of platinum metal salts.