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Detection of Hydroxide Ions in Aqueous Solutions by Steady‐State Voltammetry
Author(s) -
Abdelsalam Mmdouh Elsayed,
Denuault Guy,
Baldo M. Antonietta,
Bragato Carlo,
Daniele Salvatore
Publication year - 2001
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200103)13:4<289::aid-elan289>3.0.co;2-f
Subject(s) - hydroxide , platinum , ion , aqueous solution , steady state (chemistry) , inorganic chemistry , analytical chemistry (journal) , electrode , nickel , chemistry , rotating disk electrode , voltammetry , electrochemistry , cyclic voltammetry , square wave , limiting current , amperometry , materials science , catalysis , chromatography , physics , organic chemistry , biochemistry , voltage , quantum mechanics
The electrochemical oxidation of hydroxide ions on microdisk electrodes was studied to find the conditions where the steady‐state current can be used for analytical applications. Results are presented for the dependence of the voltammetric response on the microdisk radius, the electrode material and the hydroxide concentration. Well‐defined waves for hydroxide oxidation were obtained under steady‐state conditions with all microdisks employed. However, the steady‐state wave splits for some hydroxide concentrations and radii, but the overall current is still proportional to the concentration. The usefulness of the wave for analytical applications depends on the electrode material. Although the wave is seen on nickel, platinum and gold, the latter is the most promising for the amperometric detection of basicity of aqueous solutions. On platinum, the wave can be used but the plateau is not so well defined. On nickel, oxide formation makes measurements difficult. Under steady‐state conditions a well‐defined wave attributed to the direct oxidation of hydroxide ions was also observed on a gold rotating disk electrode. The wave height was found to be proportional to the square root of the rotation speed, thus indicating that the process was under diffusion control. The limiting current was also found to be proportional to the concentration of hydroxide ions over the range 0.05–10 mM.