氢氧化钾法与硫酸法制备硫酸铝钾的区别探讨

The Differences between the Synthesis of Aluminum Potassium Sulfate by Aluminum Foil Dissolved in KOH and in H_2SO_4

研究了氢氧化钾和硫酸溶解铝箔制备十二水合硫酸铝钾的区别,通过返滴定法测定制备过程中各阶段的铝含量,深入分析了实验过程中的相关物料守恒,发现氢氧化钾法在铝箔溶解阶段由于副反应形成Al(OH)3沉淀,导致最终产率很低,进行搅拌及降低体系浓度可很大程度上提高产率,不过仍低于硫酸法。此外,硫酸法在实验操作上也相对更简捷。因此推荐学生使用硫酸法来制备十二水合硫酸铝钾。

The differences between the synthesis of aluminum potassium sulfate by aluminum foil dissolved in KOH and in H_2SO_4 were studied. Analysis of the material balance during the entire synthesis process by back titration of aluminum ion told us that the yield of aluminum potassium sulfate was very low due to Al(OH)_3precipitation produced by side reactions during the dissolution of aluminum foil in KOH.Stiring and lowering the KOH concentration could help to promote the yield with the H_2SO_4 method still showing a higher yield. Besides, the H_2SO_4 method was easier and more convenient. In summary, the H_2SO_4 method was recommended for students to carry out the synthesis of aluminum potassium sulfate.