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氟硅酸钾容量法测硅的重现性不好,主要是由于沉淀中残留酸的影响所致。目前常用的氯化钾—乙醇洗涤后再用氢氧化钠中和残酸的方法,中和点受洗涤程度、时间、温度影响较大,效果不良,也有用氟化钾直接洗至中性,但对铝含量较高的试样,由于沉淀及残液中吸留的铝量较高,结果将显著偏高。
Potassium fluorosilicate volumetric method to measure silicon reproducibility is not good, mainly due to the impact of residual acid in the precipitate. At present, the method of neutralizing residual acid by sodium hydroxide after washing with potassium chloride-ethanol is commonly used. The neutralization point is affected by the degree of washing, the time and the temperature, and the effect is not good. The potassium fluoride is also directly washed to the neutral, However, the higher the aluminum content of the sample, due to precipitation and raffinate retention of the higher the amount of aluminum, the result will be significantly higher.