一种新型的铬(Ⅲ)离子选择性电极的研制与应用

摘要

以水杨醛和硫代氨基脲合成的席夫碱水杨醛缩-硫代氨基脲为中性载体,将其与碳粉混合,以液体石蜡为粘合剂,制备了新型的铬(Ⅲ)离子选择性电极.在室温下,电极对Cr3+的能斯特响应浓度范围为4.00×10-7~1.00×10-2 mol/L,斜率为20.31 mV/dec,检测下限为1.58×10-7 mol/L.电极的响应时间小于20s,pH使用范围广(3.20~5.80),稳定性好,使用寿命长.在选定的条件下,用固定干扰离子法(FIM)考察了10余种离子的干扰情况,结果显示,电极对Cr3+具有较好的选择性.以该离子选择性电极为指示电极,饱和甘汞电极为参比电极,用直接电位法对废水中的Cr3+进行测定,结果令人满意.%　　A sensitive film of carbon paste doped with a new schiff base Salicylaldehyde-Hydrazine-carboth-ioamide (SDHC, synthesized in the lab) as a carrier was prepared for development of a fresh chromium(Ⅲ) ion-se-lective electrode. The electrode exhibts Nernstian response to Cr(Ⅲ) over a range of 4.00×10-7~1.00×10-2 mol/L, with a slope of 20.31 mV per decade and a detection limit of 1.58 ×10-7 mol/L. It has a fast response time (less than 20 s) over the whole concentration range, and could be used for at least 2 weeks without any considerable diver-gences in its potentials. In the research, the potential of the electrode is independent of pH in the range of 3.20~5.80. The selectivity coefficient values of the proposed electrode as determined by mixed interference method(FIM) exhibits very good selectivity for Cr (Ⅲ) over a wide variety of common metal ions. Above all, the electrode has been successfully used as an indicator electrode in determining the chromium contents in the wastewater with the methord of potentiometry, and the result is excellent.