离子交换树脂预浓集薄层树脂相分光光度法测定水中铬(Ⅵ)和铬(Ⅲ)  

Thin resin phase spectrophotometric determination of chromium(Ⅵ)and chromium(Ⅲ)in water sample after ion exchange resin phase preconcentration

作　　者：曹丽华[1] 闫永胜[2] 赵干卿[2] 王赟[2] 刘燕[2] 

机构地区：[1]吉林师范大学物理学院,吉林四平136000 [2]江苏大学化学化工学院,江苏镇江212013

出　　处：《冶金分析》2006年第5期72-74,共3页Metallurgical Analysis

摘　　要：在酸性条件下,Cr(Ⅵ)能将二苯碳酰二肼(DPC)氧化成二苯偶氮碳酰(紫红色),而二苯偶氮碳酰能与还原态Cr(Ⅲ)生成阳离子型颜色更深(深紫红色)的配位化合物,用200目732#阳离子交换树脂交换吸附Cr(Ⅲ)-二苯偶氮碳酰配位化合物,形成树脂(R-)-Cr(Ⅲ)—二苯偶氮碳酰三元配位缔合体系,用薄层树脂相光度法测定Cr(Ⅵ)含量。用KMnO4氧化溶液中Cr(Ⅲ)为Cr(Ⅵ),同法测定总铬(∑Cr),通过差减法计算Cr(Ⅲ)含量。由于配位及与树脂离子交换缔合的选择性,使本法选择性极好,除Fe3+外,其余共存离子基本不干扰测定。三元体系的形成及树脂富集作用提高了灵敏度,本法灵敏度比水相光度法高11倍,ε540=4.4×105L.mol-1.cm-1。6次测定5.0μgCr(Ⅵ),RSD为2.30%。实测了工业废水和天然水中Cr(Ⅲ)和Cr(Ⅵ)含量,加标回收率97.0%～101.0%。It based on that diphenylcarbzide（DPC）can be oxidized by chromium（Ⅵ） to amaranthine diphenylcarbazone, which can react with chromium （Ⅲ） to form a claret cation coordination compound, i. e. chromium（Ⅲ）- diphenylcarbazone in acid medium. This coordination compound can exchange with the cation on the surface active sites of model 732 cation exchange resin,so a R^- -Cr（Ⅲ）- diphenylcarbazone ternary associative system is produced, and chromium（Ⅵ）is determined by thin resin phase spectrophotometry. Chromium（Ⅲ）is oxidized to chromium（Ⅵ） by potassium permanganate completely . Total chromium is determined by the same method and then chromium（Ⅲ）Dcan be calculated by minus. Due to the selectivity of coordination compound and ion exchange of resin, the method has good selectivity（besides of Fe^3 ＋ , most other co-exizting ions didn＇t interfere in the determination）. It has a apparent molar absorptivity of 4.4 × 105 L·mol^-1·cm^-1, which is 11 times higher than water phase spectrophotometry. The linear range is in the range of 0 - 4.0 μg/mL, and the detection limit is 0. 012 μg/L. The relative standard deviation is 2. 3 % for the determination of 5.0μg Cr（Ⅵ））（ n = 6）. The method has been applied to the analysis of chromium in industrial waste water and natural water with recovery of 97.0 96 - 101.0 %

关 键 词：离子交换树脂 树脂相分光光度法 铬(Ⅵ) 铬 (Ⅲ) 

分 类 号：O657.32[理学—分析化学]