Development of a voltammetric method for the determinationof iron(III) in Zn-Fe alloy galvanic baths

摘要

A square wave voltammetric method whith a static mercury drop electrode (SMDE) was developed for the quantitative determination of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery tests were car- ried out. 0.50 mol L -I sodium citrate (pH 6.0) or 0.20 mol L -I oxalic acid (pH 4.0) were applied as supporting elec- trolytes resulting in both cases in a peak potential of about -Q.20 V vs. AgiAgCI (saturated KCI). The iron (III) con- centration in the alloy bath was 9.0 x 10-4 mol L -I. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the elec- trolytes studied, with linear response ranges from 1.0 x 10-6 to 1.2 x 10-4 mol L -1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and man- ganese (II) that can hinder the Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously.