Anodic Oxidation of Potassium Iodide Solution (Ⅰ)

요오드화칼륨 수용액의 양극산화 (제1보)

  • Nam, Chong-Woo (Department of Chemical Engineering, Inha University) ;
  • Kim, Hark-Joon (Department of Chemical Engineering, Inha University)
  • 남종우 (인하대학교 공과대학 화학공학과) ;
  • 김학준 (인하대학교 공과대학 화학공학과)
  • Published : 1973.10.30

Abstract

To investigate the mechanism of the reaction of electrolytic oxidation of iodide to iodate ions, polarization curves are determined in various kinds of solution using electrodeposited lead peroxide and platinum anodes. It was observed from the polarization curves that the limiting current is exists at concentration 1.5 M of potassium iodide, and these limiting current disappeared as potassium hydroxide was added up to concentration of 0.1 M. while in case of platinum anode, limiting current did not appear in dilute potassium iodide solution. These results are owing to the chemical reaction, $PbO_2+2I^{-}+2H^+{\to}PbO+I_2+H_{2}O$ ocurring at the surface of lead peroxide anode. Also, we studied to obtain the optimum conditions of electrolytic preparation of iodate from iodide solution using a cell without the diaphragm. The results are that; (a) addition of potassium dichromate at the anti-reducing agent is proper in concentration of 0.1 g/l, (b) electrolytic temperature is not so much effective in raising the current efficiency, (c) current efficiency is increased with current density, and (d) electrolysis is the most effective in weak alkaline solutions.

요오드화칼륨으로부터 요오드산칼륨까지의 양극산화시 그 반응의 내용을 검토키 위하여 전착과산화납 및 백금양극을 사용하여 각종 농도의 요오드화칼륨 수용액중에서 분극곡선을 측정한 결과 요오드화칼륨의 1.5M이하에서 한계전류가 존재하며 0.1M의 수산화칼륨을 가하였을때는 한계전류는 나타나지 않음을 알았다. 한편 백금양극의 경우에는 과산화납양극에서와 같이 희박한 요오드화 칼륨수용액중에서 한계전류가 나타나지 않으며 이는 과산화납양극표면에서 $PbO_2+2I^{-}+2H^+{\to}PbO+I_2+H_{2}O$와 같은 화학반응에 기인함을 알았다. 무격막전해조를 사용하여 요오드화염으로부터 요오드산염까지의 전해제조시 가장 효율적인 전해조건에 관하여서도 검토한 결과, (a)환원방지제인 중크롬산칼륨의 첨가는 0.1g/l의 농도가 적당하였으며, (b)전해온도는 전류효율에 큰 영향을 미치지 않았으며, (c)전류밀도가 증가함에 따라 전류효율은 상승하였고, (d)전해중 전해액의 액성은 약알카리성이 가장 효율적이었다.

Keywords

References

  1. 本誌 v.15 C.W. Nam;H.J. Kim
  2. Trans. Electrochem. Soc. v.62 H.H. Willard;R.R. Ralston
  3. Ind. Eng. Chem. v.51 C.L. Mehltretter;C.S. Wise
  4. Bull. Osaka Ind. Resarch Inst. v.7 E. Torigai;E. Ishii
  5. J.Electrochem. Soc. v.109 Y.Aiya;S. Fujii;K. Sugino
  6. 本誌 v.14 C.W. Nam;H.J. Kim
  7. Scott's Standard Methods of Chemical Anal.(15th Ed.) v.1 N.H. Furman