氟铝络合滴定计算分析法测定乙醇-水溶液介质中的铝

Determination of Aluminium in Alcohol-Water Solution by Fluoride-Aluminium Complexometric Titration with a Mathematical Model

导出了氟离子标准溶液滴定铝离子的络合滴定计算分析的数学模型。以氟离子选择性电极作指示电极,利用氟离子与铝离子在乙醇水溶液中产生沉淀,仅形成3种络合物的现象,先计算出3个条件累积稳定常数,再计算出铝离子的分析浓度。通过氢氧化铝的条件溶度积常数,求出溶液控制的pH值约为4.7。讨论了滴定数据的位置对测定结果的影响。

The mathematical model was made for the determination of aluminium ions in fluoride-aluminium complex formation titration with fluoride ion solution as titrant and fluoride ion selective electrode as indicating electrode. In alcohol-water solution fluoride ions and aluminium ions form precipitate and only form AIF(2+), AIF(+) and AIF(3). The three conditional accumulative stability constants were worked out and then the analytical concentration of aluminium ions was measured. By way of the conditional solubility product of aluminium hydroxide, it was found that the pH of the solution measured should be controlled around 4.7. The reason that the position of the titration data affects the accuracy of determined result was also discussed.