CYCLIC VOLTAMMETRIC STUDIES OF CERTAIN INDUSTRIALLY POTENTIAL IRON CHELATE CATALYSTS

Cyclic voltammetry of iron-EDTA and iron-DETPA, in different supportin g electrolytes showed electrochemical reversibility in ammonium citrat e at pH 8.0, while quasi-reversible nature was noticed with iron-NTA. The absence of electroactive peaks when adding a polyhydric alcohol su ch as mannitol (providing greater stability to the chelate in alkaline pH) or a tertiary amine such as triethanolamine (as an organic buffer ) to the supporting electrolyte enabled the use of CV for quantitative analysis of iron in a complex matrix containing these ingredients. Th e decrease in the diffusion coefficient of Fe(III)-chelate with an inc rease in the organic buffer suggested the need for limiting the concen tration of the amine in order to obtain efficient mass transport while providing better pH control, when such a solution is required for the oxidation of the sulfide/hydrosulfide ion to elemental sulfur.