凍結時に促進されるシアン化物イオンによるヘキサシアノ鉄(III)酸イオンの還元反応 [in Japanese] Acceleration of Reduction of Ferricyanide Ion by Cyanid Ion in Aqueous Solution under Freesing Process [in Japanese]
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Ferricyanide ion ([Fe(CN)<sub>6</sub>]<sup>3-</sup>) reduction by cyanide ions (CN<sup>-</sup>) in an aqueous solution was markedly enhanced in freezing, in which ferricyanide ions were reduced to ferrocyanide ion ([Fe(CN)<sub>6</sub>]<sup>4-</sup>). When the concentration of potassium hexacyanoferrate (III) (K<sub>3</sub>[Fe(CN)<sub>6</sub>]) was fixed at 1.21×10<sup>-3</sup>mol dm<sup>-3</sup>, the yield of the redox reaction for potasium cyanide (KCN) concentration added increased monotonically until a 1.53×10<sup>-3</sup> mol dm<sup>-3</sup> concentration. The redox reaction was found to strongly depend on initial solution pH, in which the yield for pH=9∼11 was 85% and pH=11∼13 was 100%.<br>Comparing several freezing speeds showed that the rate of reaction was enhanced with increasing freezing speed. The rate and yield were enhanced to be come strongly dependent on the concentration of sodium chloride (NaCl) added.<br>These results suggest that the redox reaction in freezing strongly depended growing ice crystal.
- Jitsumu Hyomen Gijutsu
Jitsumu Hyomen Gijutsu 50(2), 225-230, 1999-02-01
The Surface Finishing Society of Japan