K_2SiF_6不经过滤直接水解滴定测SiO_2

Determination of Silicon Dioxide by Direct Hydrolysis Titration of K_2SiF_6 without Filtering Separation

本法基于K_2SiF_6沉淀后,不过滤分离,用KOH溶液中和母液中的酸至中性,当溶液中存在适量的F^-和K^+离子时,它们既能抑制K_2AlF_6等干扰物质的水解,又不影响K_2SiF_6完全水解.避免了现行K_2SiF_6法过滤分离的麻烦手续,防止了因转移和洗涤时K_2SiF_6的部分损失引起的负误差,消除了因可能产生K_2AlF_6沉淀引起的正误差.其准确度不低于动物胶重量法.用本法测定标准样品,标准偏差在0.20～0.24%间.为测定含SiO_2在40～80%的瓷用硅酸盐样品提供了一个准确快速的方法.

This study is made to deteminate silicon dioxde by neutralizing the acid in the mother solution with standard KOH solution without separating the precipitate of K2SiF6. It is found that the existence of F~ and K+ ions in the. solution both inhibites the hydrolysis of the interfering material like K2A1F6 ,and matters nothing to the complete hydrolysis of K2SiF6. With the separation of precipitate avoided ,the minus deviation caused by the loss of K2SiF6 and plus deviation caused by the hydrolysis of the K2AlF6 precipitate is eliminated. The accuracy of this method is not lower than glue gravimetric method. This method is used to determinate the standard sample. Its standard deviation is between 0. 20% and 0. 24%. Thus,an accurate and quick method is provided for the determination of silicate samples which contain silicon dioxide about 40~80%.