摘要
以线性扫描伏安法研究了蟹壳粉-铋修饰碳糊电极上Cr（Ⅵ）的电化学行为及其吸附富集行为。天然蟹壳粉具有吸附富集铬酸根的作用,吸附过程遵循扩展Langmuir等温吸附模型。金属铋能够催化铬酸根的电化学还原,使其还原峰电流增加,峰电位发生负移,从而实现对Cr（Ⅵ）的电化学测定。优化的实验条件为：pH=2.6（Na2HPO4-柠檬酸）,静止时间50 s,吸附时间20 min,沉积电位-0.5 V,扫速0.05 V/s。在优化实验条件下,存在两段线性范围,分别为1.0×10^-8-1.0×10^-6mol.L^-1和1.0×10^-5-1.0×10^-3mol.L^-1,检出限为1.0×10^-8mol/L。干扰实验结果表明,Cr（Ⅲ）和SO42-离子对检测没有干扰。方法用于污水中铬（Ⅵ）的测定,加标回收率为94%-106%,相对标准偏差为3.1%。
The electrochemical behavior,adsorption and preconcentration of Cr（Ⅵ）from aqueous solution on hermit crab shell powder and bismuth modified carbon paste electrode were studied by linear sweep voltammetry.The adsorption and preconcentration of CrO2-4on hermit crab shell powder followed the extended Langmuir adsorption isotherm model.The electrochemical reduction of Cr（Ⅵ）in acidic solution was catalyzed by the electrochemically deposited bismuth film to increase the reduction peak current and the positive shift of reduction peak potential.The experimental conditions were optimized.The optimized conditions were as the follows：pH=2.6 disodium hydrogen phosphate-citric acid buffer,quiet time：50 s,adsorption time：20 min,deposition potential：-0.5 V and scan rate：0.05 V/s.Experimental results showed that Cr（Ⅲ） and SO2-4ions would not interfere with the detection of Cr（Ⅵ）.The electrode also could be used to detect CrO2-4ion with higher sensitivity.The method was used in the determinations of dichromate in the concentration ranges of 1.0×10^-8-1.0×10^-6 mol·L^-1and 1.0×10^-5-1.0×10^-3 mol·L^-1 in aqueous solution with a detection limit of 1.0×10^-8 mol/L.The spiked recoveries were in the range of 94%-106% with RSD of 3.1%.
出处
《分析测试学报》
CAS
CSCD
北大核心
2010年第12期1205-1208,共4页
Journal of Instrumental Analysis
基金
国家自然科学基金资助项目(20875063)
辽宁省教育厅资助项目(2004-c022)
沈阳市科技局资助项目(2007-GX-32)
关键词
Cr(Ⅵ)
线性扫描伏安法
天然蟹壳粉
铋膜
化学修饰电极
吸附富集
Cr（Ⅵ）
linear sweep voltammetry
natural hermit crab shell powder
bismuth film
chemically modified electrode
adsorption and preconcentration
