氢氧化镁分解动力学的研究

Study on the thermal decomposition kinetics of magnesium hydroxide

以硼泥为原料与硫酸反应制备出七水硫酸镁,以氢氧化钠为沉淀剂制备出符合标准HG/T3607-2000的氢氧化镁.利用XRD,SEM和TEM对氢氧化镁进行了表征,DTA-TG对氢氧化镁的热分解动力学进行了研究.XRD结果表明:制备粉体为单一Mg(OH)2.SEM和TEM结果表明:样品为片状或针状纤维,片直径大小不一,在20～50nm之间,针状纤维形状不规则,大小不一致,长度在20～100nm之间.利用Kissinger法和Ozawa法计算出的氢氧化镁热分解反应活化能分别为135.14和141.61kJ·mol-1.利用Coats-Redfern法和Dolye法判断氢氧化镁热分解反应机理函数为A1.5.

Taken boron mud and sulfuric acid as raw materials,bitter salt was prepared. Taken sodium hydroxide as precipitation, magnesium hydroxide was prepared and its quality meets the standards of HG/T 3607-2000. XRD, SEM and TEM were used to characterize the sample, the thermal decomposition of magnesium hydroxide was studied by DTA-TG. It was confirmed that the prepared power is only magnesium hydroxide by XRD. The SEM and TEM results suggested that the sample is a mixture of sheet and acicular fibre, the diameter of sheet power is 20 - 50 nm, the acicular fibre is abnonnity and it＇ s length is 20 - 100 nm. The activation energy of decomposition which was estimated by Kissinger and Ozawa are 135.14 and 141.61 kJ.mol^-1. Decomposition reaction of magnesium hydroxide was controlled by A1.5 according to the Coats-Redferm and Dolye equations.