Spectrophotometric Determination of Iron and Chromium in Cr-Electroplating Baths at the Helwan Engineering Industrial Company Using Pyrocatechol as Indicator

Abstract

The pyrocatechol (P.C.) was used as a selective spectrophotometric reagent for Fe(III) and Cr(VI), under optimum conditions. The effects of pH and temperature on the spectra of iron–P.C. chelate and chromium–P.C. chelate were studied to select the optimum conditions for determination of iron(III) and chromium(VI) in synthetic and in electroplating bath solutions. The suitable conditions for determination of Cr(VI) and Fe(III) were 95°C, and 25°C at λ max= 515 and 585 nm at the same pH = 5.0, respectively. The method succeeded for determination of Cr(VI) and Fe(III) with recovery 99.31–101.6%. The standard deviation was found to be 0.98–1.6 which refered to the reproducibility and reliability of the applied procedures. The suggested procedures using P.C. indicator were applied successfully for analysis of Fe and Cr in 16 samples collected from the chromium-electroplating bath containing Fe(III) as contaminant. These procedures were also used for monitoring Fe(III) and Cr(VI) in the presence of each other during the electroplating of steel utensils at the Helwan Engineering Industrial Company, Factory 99.