The electrolysis of a carbonate-borate solution with a platinum anode—II. Relation between current efficiency and perborate concentration

✍ Scribed by P.M.v.d. Wiel; L.J.J. Janssen; J.G. Hoogland

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 533 KB
• Volume: 16
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(71)85111-3

✦ Synopsis

The current efficiency R (corrected for the chemical disproportionation of HtOI in the bulk of electrolyte) of the electrolytic formation of perborate decreases with increasing concentration of H801d_ The factors causing this decrease were investigated. The relation between R and [H,O,] and the diffusion coefficient of HaOI were determined under various conditions. The relation between the thickness of the Nemst diffusion layer and the rate of oxygen evolution was established. The stability of peroxocarbonate at -15°C was also examined. The slope of the linear R/[H,O,] curve increases with decreasing cd, with increasing pH and temperature, by replacement of Naf by K +, rotation of the anode and in absence of borate. The decrease of R with increasing [H,O,] is caused by two reactions, oxidation of HaOI at the anode and reaction between H,Ot and a peroxocarbonate compound in the electrolyte. R&ml+Le rendement du courant R de la formation 6lectroIytique de perborate diminue en augmentant la concentration de HaOB. (R est rectifi6 pour la disproportion de H,OI dam la masse d%lectrolyte.) Les facteurs clui causent cette d6croissance ont &6 Btudib. La relation entre R et [HzOI] et le coefficient de diffusion de HzOI ont et6 d&err&& dans des circonstances vari6es. La relation entre l'dpaisseur de la couche de diffusion de Nemst et la mesure d'&olution oxy@ne a et4 Btablie. La stabilitd de peroxocarbonate & -15°C a 6t6 &udi&e aussi. La pente de la courbe R/[H,O,] lintiie augmente en diminuant la dens36 de courant, en augmentant Ie pH et la temperature, en remplacant Na+ par IC+, en faisant toumer l'anode et en l'absence de borate. La diminution de R en [H,O,] augmentant, est cau.& par 2 r&actions, l'oxydation de H108 a I-anode et la reaction entre H,OZ et une combinaison chirnique de peroxocarbonate dans l'&ctrolyte.