Dissolution behaviour of platinum by electro-generated chlorine in hydrochloric acid solution

• Published in: Journal of chemical technology and biotechnology (1986) Vol. 88; no. 7; pp. 1212 - 1219
• Main Authors: Kim, Min-seuk, Lee, Jae-chun, Park, Sang-woon, Jeong, Jinki, Kumar, Vinay
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.07.2013; Wiley; Wiley Subscription Services, Inc
• Subjects: activation energy; Applied sciences; Chemical engineering; chemical reaction control; Crystallization, leaching, miscellaneous separations; dissolution; electro-generated chlorine; Exact sciences and technology; Heat and mass transfer. Packings, plates; platinum; Reactors; platinum; Chemical reaction; electro-generated chlorine; Lixiviation; Regulation; chemical reaction control; Thermodynamic properties; Dissolution; Activation energy; Mass transfer
• ISSN: 0268-2575; 1097-4660
• DOI: 10.1002/jctb.3957

Background Depletion of primary resources, stringent environmental regulations, and the requirement for energy efficient and eco‐friendly processes have created research interest in recovering Pt from secondary resources using electro‐generated chlorine in HCl solution. Results Platinum dissolution rate was found to increase by a factor of 2.5 by increasing the HCl concentration from 3.0 to 5.0 mol L‐1 at 70°C, while maintaining total chloride ions at 5.0 mol L‐1 with NaCl. Increasing the aqueous chlorine concentration made no improvement to the dissolution rate. A theoretical calculation of distribution for chlorine species showed a predominance of Cl3− ions in comparison with Cl2(aq) upon increasing the acid concentration to above 5.0 mol L‐1; raising temperature also increased the dissolution rate. The activation energies of Pt dissolution in the 5.0 mol L‐1 HCl solution were 82.3 and 83.5 kJ mol‐1 at 5.0 and 15 mmol L‐1 aqueous chlorine concentration, respectively. Conclusions Eco‐friendly electro‐generated chlorine leaching was applied for the dissolution of Pt in hydrochloric acid solutions. Increasing HCl concentration and solution temperature effectively enhanced Pt dissolution during leaching. A quantitative investigation of Pt dissolution rate verified the chemical reaction control of Pt dissolution rather than mass transfer.