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食品用硅藻土助滤剂中硅的测定方法主要有动物胶重量法和氢氟酸重量法.本文提出试样经氢氧化钾熔融后在强酸介质中与氟化铵和氯化钾生成六氟合硅酸钾(K_2SiF_6)沉淀,沉淀离心分离后水解析出氢氟酸,用氢氧化钠标准溶液进行滴定.1 试剂氯化钾乙醇溶液:5%,称取氯化钾5.0g溶于水50ml,加乙醇(95%)50ml.氢氧化钠标准溶液:0.5mol·L~(-1)2 操作方法准确称取硅藻土样品0.1～0.2g于镍坩埚中,加入氢氧化钾固体1～2g,放入550℃马弗炉中熔融15min,取出冷却,加少量水用塑料棒搅动溶解,转入塑料烧杯中,用少量水洗涤坩埚2～3次后合并洗涤液于塑料烧杯中,使总体积不超过15ml为宜.
Food diatomite filter aid in the determination of silicon are mainly animal glue gravimetric method and hydrofluoric acid gravimetric method.This paper presents the sample after potassium hydroxide melting in a strong acid medium with ammonium fluoride and potassium chloride to generate six Fluorosilicate potassium silicate (K_2SiF_6) was precipitated, and the precipitate was centrifuged to hydrolyze hydrofluoric acid and titrated with sodium hydroxide standard solution.1 Reagents Potassium chloride solution in ethanol: 5%, weighed in potassium chloride 5.0g Water 50ml, add ethanol (95%) 50ml. Sodium hydroxide standard solution: 0.5mol · L -1 (2) Operation method accurately weighed diatomite samples 0.1 ~ 0.2g in nickel crucible, add potassium hydroxide solid 1 ~ 2g, melted in a muffle furnace at 550 ℃ for 15min, removed and cooled, add a small amount of water agitated with a plastic rod to dissolve, transferred to a plastic beaker, with a small amount of water after washing the crucible 2 to 3 times the combined washing liquid in a plastic beaker , So that the total volume does not exceed 15ml is appropriate.