Determination of Fe²⁺ and Fe³⁺ Ratio in Iron Plating Bath by Measurement of Oxidation-Reduction Potential

Abstract

A trial has been conducted to apply Oxidation-Reduction Potential (ORP) to the on-line monitoring of Fe²⁺ and Fe³⁺ in a chloride bath for iron plating having iron concentration of 160230 g/l and Fe³⁺/Fe²⁺ concentration ratio of 0.01 0.12.From the analysis of ORP's at different bath pH (0.51.4), temperature (2095°) and flow rate (0200 cm/s), it was found that the concentration ratio Fe³⁺/Fe²⁺ in the plating bath can be directly obtained by measurements of ORP and bath temperature. Also, the precision of this method was satisfactory.
The present ORP method does not need such operations of chemical analysis as dilution and cooling of the sample solution, and addition of chemical reagents which contaminates the bath. Thus, it is concluded that Fe³⁺/Fe²⁺ ratio can be determined easily and continuously by simple procedure and apparatus.