线性扫描伏安法测定电镀铬槽液中铬(Ⅵ)和铁(Ⅱ)  

Determination of chromium(Ⅵ) and iron (Ⅱ) in eletrodeposited chromium electrolyte by linear sweep voltammetry

作　　者：乔永莲[1] 沙春鹏 董宇[2] 刘冰[1] 

机构地区：[1]沈阳飞机工业(集团)有限公司,辽宁沈阳110850 [2]中国人民解放军驻沈阳飞机工业(集团)有限公司军事代表室,辽宁沈阳110034

出　　处：《冶金分析》2016年第6期18-22,共5页Metallurgical Analysis

基　　金：国家科技重大专项课题(2013zx04001041)

摘　　要：以光谱纯石墨电极作为工作电极,采用三电极体系对镀铬槽液进行动电位极化扫描,利用电活性物质的质量浓度在石墨电极表面的还原峰与氧化峰电流值的变化关系,分别建立了线性扫描伏安法测定电镀铬槽液中Cr^(6+)和Fe^(2+)的方法。结果表明,在扫描速率为50~60mV/s,酸度为pH 2.0,测试温度为20℃时,测定结果最佳。Cr^(6+)在0.43V(vs.饱和甘汞电极,SCE)发生还原,Cr^(6+)的质量浓度在2~14g/L范围内,其质量浓度与还原峰峰电流呈线性,线性回归方程的相关系数R2=0.999;Fe^(2+)在0.52V(vs.饱和甘汞电极,SCE)发生氧化,Fe^(2+)的质量浓度在5~15g/L范围内,其质量浓度与氧化峰峰电流呈线性,线性回归方程的相关系数R2=0.998。实验方法用于测定实际槽液中Cr^(6+)和Fe^(2+),结果的相对标准偏差(RSD,n=10)在1.1%~1.3%之间。将按照实验方法对实际槽液中Cr^(6+)和Fe^(2+)的测定结果与硫酸亚铁铵滴定法测定Cr以及原子吸收光谱法测定Fe的结果进行比对,吻合性较好。The potentiodynamic polarization scanning of eletrodeposited chromium electrolyte was conduc- ted with three-electrode system using spectroscopically pure graphite electrode as working electrode. Based on the variation relationship between reducing peak current and oxidizing peak current of mass concentra- tion of electro-active materials on graphite electrode surface, the determination method of Cr^6＋ and Fe^2＋ in eletrodeposited chromium electrolyte by linear sweep voltammetry was established. The results showed that the optimal experimental conditions were as follows, the scanning rate was 50-60 mV/s, the pH was 2.0, and the testing temperature was 20 ℃. Cr^6＋ was reduced at 0.43 V （vs. saturated calomel electrode, SCE）. The mass concentration of Cr^6＋ in range of 2-14 g/L showed linearity to the reducing peak current, and the correlation coefficient of linear regression equation was R2：0. 999. Fe^2＋ was oxidized at 0. 52 V （vs. SCE）. The mass concentration of Fe^2＋ in range of 5-15 g/L showed linearity to the oxidizing peak current, and the correlation coefficient of linear regression equation was R2 =0. 998. The proposed method was applied to the determination of Cr^6＋ and Fe^2＋ in actual chromium electrolyte. The relative standard deviations （RSD, n= 10） were between 1. 1% and 1. 3%. The determination results were compared with those obtained by ammonium ferrous sulfate titration for Cr and atomic absorption spectrometry for Fe. The consistency was good.

关 键 词：电镀铬槽液 光谱纯石墨电极 动电位极化 铬(Ⅵ) 铁(Ⅱ) 线性扫描伏安法 

分 类 号：TQ153.11[化学工程—电化学工业]