NH_(4)Al(SO_(4))_(2)·12H_(2)O脱水过程及其热力学与动力学性能

Dehydration Process of Ammonium Aluminum Sulfate Dodecahydrate and Its Thermodynamics and Kinetics Research

通过热重-差热分析仪(TG/DTA)测试了NH_(4)Al(SO_(4))_(2)·12H_(2)O的升温脱水过程,并对其脱水过程进行热力学和动力学分析。结果表明,NH_(4)Al(SO_(4))_(2)·12H_(2)O的脱水过程分为2步,第1次脱去9个水分子,形成NH_(4)Al(SO_(4))_(2)·3H_(2)O;第2次脱去剩余的3个水分子,形成NH_(4)Al(SO_(4))_(2)。热力学分析NH_(4)Al(SO_(4))_(2)·12H_(2)O脱水过程中,脱落的液态水分子随即气化。动力学分析NH_(4)Al(SO_(4))_(2)·12H_(2)O脱水过程,脱去9个水分子的反应活化能为93.53 kJ/mol,脱去3个水分子的反应活化能为118.7 kJ/mol。

The dehydration process of NH_(4)Al(SO_(4))_(2)·12H_(2)O under the heating stage was tested by thermogravimetricdifferential thermal analysis(TG-DTA),and the dehydration process was analyzed by the thermodynamical and kinetic methods.The results showed that the dehydration process of NH_(4)Al(SO_(4))_(2)·12H_(2)O was divided into two steps.In the first step,9 water molecules were dehydrated from NH_(4)Al(SO_(4))_(2)·12H_(2)O to form NH_(4)Al(SO_(4))_(2)·3H_(2)O;the remaining 3 water molecules were dehydrated and it became to NH_(4)Al(SO_(4))_(2).Thermodynamic analysis of NH_(4)Al(SO_(4))_(2)·12H_(2)O dehydration process showed that the shed liquid water molecules were then vaporized.Kinetic analysis of NH_(4)Al(SO_(4))_(2)·12H_(2)O dehydration process indicated that the reaction activation energy of 93.53 kJ/mol for the removal of 9 water molecules,and the activation energy of 118.7 kJ/mol for the removal of 3 water molecules.