过氧化氢-耐尔蓝体系催化动力分光光度法测定冶炼废水中微量铜

Determination of Trace Copper in Smelting Wastewater by Catalytic Dynamic Spectrophotometry with Hydrogen Peroxide and Nell Blue System

随着水土环境的日益恶化,监控包括铜在内的重金属污染对水土环境的危害越来越受到重视,有的重金属通过食物链以有害浓度在人体内积累,严重危害人体健康。基于在柠檬酸缓冲溶液反应介质中,过氧化氢在Cu(Ⅱ)的催化下能氧化耐尔蓝褪色,其褪色程度与Cu(Ⅱ)含量成正比,从而建立了催化分光光度法测定微量Cu(Ⅱ)的新方法。选择的反应介质柠檬酸缓冲溶液具有某些表面活性剂的作用,浅析了柠檬酸缓冲溶液在工作中对耐尔蓝起增敏作用的原因,且柠檬酸作为植物提取物,具有无毒环保,易于分解,可调节酸度和化学性质稳定等优点。通过实验确定了方法的最大吸收波长为635 nm,柠檬酸缓冲溶液的最佳使用量为1.0 mL,耐尔蓝和过氧化氢的最佳用量分别为1.75和1.0 mL,反应时间和反应温度分别为11 min和90℃,Cu(Ⅱ)含量在0~0.32μg/mL内与吸光度的差值呈线性关系。对铜标准溶液和标准物质进行测定,测定结果的相对误差在2.8%~3.8%,相对标准偏差在3.8%~4.7%,表观摩尔吸光系数为5.0×10^(6)L/(mol•cm)。方法用于废水中微量Cu(Ⅱ)的测定,加标回收率在95.6%~102%。方法具有操作简便、选择性较好、有较灵敏度高、分析成本低、使用的试剂较为环保等优点。

With the increasingly deterioration of water and soil environment,more and more attention has been paid to monitoring the harm caused by heavy metal pollutions to water and soil environment,including copper.Some heavy metals accumulate in the human body in harmful concentrations through the food chain,seriously endangering human health.Based on the fact that hydrogen peroxide can oxidize Nell blue for fading under the catalysis of Cu(Ⅱ)in the reaction medium of citric acid buffer solution,and the fading degree is proportional to the Cu(Ⅱ)content,a new catalytic spectrophotometric method for the determination of trace Cu(Ⅱ)was established.The selected reaction medium,citric acid buffer solution,has the function of some surfactants.The reasons for the sensitizing effect of citric acid buffer solution on Nale blue in work were analyzed.In addition,as a plant extract,citric acid has the advantages of non-toxic environmental protection,easy decomposition,adjustable acidity and stable chemical properties.The maximum absorption wavelength of the method was 635 nm,the optimal dosage of citric acid buffer solution was 1.0 mL,the optimal dosage of Nell blue and hydrogen peroxide were 1.75 and 1.0 mL,the reaction time and reaction temperature were 11 min and 90℃,respectively.There was a linear relationship between Cu(Ⅱ)contents and absorbances in the Cu(Ⅱ)content ranged of 0—0.32μg/mL.The relative error and relative standard deviation of the determination results for copper standard solution and standard materials were 2.8%—3.8%and 3.8%—4.7%,respectively.The apparent molar absorption coefficient was 5.0×10^(6) L/(mol•cm).The method has been applied to the determination of trace Cu(Ⅱ)in wastewater with the recovery between 95.6%and 102%.This work has the advantages of simple operation,good selectivity,high sensitivity,low analysis cost and environmentally friendly reagents.