硫氰酸盐分光光度法测定废催化剂中钨含量

采用硫氰酸盐分光光度法测定废催化剂中钨含量,存在样品难分解、流程复杂等问题。实验采用盐酸-硝酸-高氯酸混合酸分解样品,加入氢氧化钠使铁、锰、钒、镍、铜等元素形成沉淀,而钨以钨酸盐形式存在于溶液中以达到分离,用氯化亚锡-三氯化钛作还原剂,在盐酸介质中,将钨(Ⅵ)还原为钨(Ⅴ)与硫氰酸盐形成黄色的络合物,建立了硫氰酸盐分光光度法测定废催化剂中钨的分析方法。实验表明:钨的质量浓度在2.0~12.0μg/mL范围内与其对应的吸光度符合朗伯比尔定律,相关系数为0.9998。将该实验方法用于测定4个废催化剂样品中钨含量,测定结果的相对标准偏差(RSD,n=7)在0.54%~1.99%之间。按照该实验方法测定4个废催化剂样品中钨,测定结果与电感耦合等离子体原子发射光谱法(ICP-AES)测定结果一致。

Determination of Tungsten in Waste Catalyst by Thiocyanate Spectrophotometry

There are some disadvantages in the analytical method of determining tungsten content by thiocyanate spectrophotometry in waste catalyst,such as the difficulty of sample dissolving and the complex process.A method for the determination of W in waste catalyst by spectrophotometry was established.The sample was dissolved with hydrochloric acid,nitric acid and perchloric acid.After perchloric acid smoke,sodium hydroxide was added to precipitate iron,manganese,vanadium,nickel,copper and other elements,while tungsten exists in the solution as tungstate to achieve separation.Stannous chloride titanium trichloride was reducing agent,which can reduce tungsten(Ⅵ)to tungsten(Ⅴ)in the medium of hydrochloric acid and form a yellow complex with thiocyanate.The results showed that,lambert-beer law was obeyed for tungsten within the range of 2.0~12.0μg/mL,with the correlation coefficient R2=0.9998.The relative standard deviation(RSD,n=7)were between 0.54%and 1.99%.Tungsten in four waste catalyst samples were determined by the experimental method,which the results were consistent with ICP-AES.