Critical Anode Potential in the Chlorate Process
2006 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 153, no 1, D14-D20 p.Article in journal (Refereed) Published
Anodic polarization curves on dimensionally stable anodes (DSAs) of RuO2/TiO2 in chlorate electrolyte bend to a higher Tafel slope at the critical potential (E-cr) of approximately 1.2 V vs Ag/AgCl. Operating the chlorate process above E-cr leads to increased oxygen evolution and higher potential losses. In this study the impact of different electrolyte parameters and electrolyte impurities on the risk of reaching/exceeding E-cr was investigated. A dependency of Cl- concentration on E-cr of about -90 mV/dec C-Cl(-) was found at pH 2. An addition of Na2Cr2O7 to chlorate electrolyte is necessary in order to keep a high current efficiency on the cathode but was found to increase the anode potential and thereby increase the risk of exceeding E-cr at galvanostatic operation. Additions of impurities as 30 g/L Na2SO4 or 100 ppm Si (added as SiO2) resulted in increased anode potentials, but adding 1.4 g/L KH2PO4 or 1 g/L HF did not have significant short-term impact on the potential. The anode potential as well as E-cr decreased with increased temperature. A high temperature is beneficial in terms of the decreased anode potential, which outweighs the negative effect of a decrease in Ecr.
Place, publisher, year, edition, pages
2006. Vol. 153, no 1, D14-D20 p.
Anodes, Anodic polarization, Electrolytes, Impurities, Oxygen, Thermal effects, Anode potential, Chlorate process, Electrolyte impurities
IdentifiersURN: urn:nbn:se:kth:diva-8148DOI: 10.1149/1.2135216ISI: 000234142400050ScopusID: 2-s2.0-33645515270OAI: oai:DiVA.org:kth-8148DiVA: diva2:13394
QC 201008312008-03-272008-03-272010-11-22Bibliographically approved