用天然水镁石球磨法制备Mg-Al水滑石的实验研究

Synthesis of Mg-Al Layered Double Hydroxides from Natural Brucite by Ball Milling

以水镁石、硝酸铝和碳酸氢钠为原料,利用球磨方法通过机械力化学作用合成了Mg-Al水滑石,考查了球磨速度、球磨时间对合成水滑石的影响。研究表明,提高球磨转速有利于水滑石的形成与晶化,同时也有利于Al2O3的析出。适当延长球磨时间有利于水滑石的形成和结晶,但球磨时间过长,水滑石结构破坏。在500 r/min转速下球磨3 h制备的水滑石纯度最高、结晶最好。用该方法制备的水滑石粒径较大,结晶度较低,热学行为特殊,可能与结构中富镁、贫铝有关。

Mg-A1 layered double hydroxides （ Mg-A1 LDHs） were synthesized by ball milling from natural brucite, AI（N03）3 .9H20 and NaHCO3. The effects of ball milling speed and milling time on the formation of Mg-A1 LDHs were investigated. The results indicated that the amount and crystallinity of Mg- A1 LDHs increased as the ball milling speed increasing. A1203 was formed when the ball milling speed was over 500 r/min and as the ball milling speed increasing. Lengthening the ball milling time in a certain range could enhance the crystallization of Mg-A1 LDHs. However, the structure of Mg-A1 LDHs started to destroy when the milling time was over 3 h at 500 r/min. Mg-A1 LDHs synthesized at 500 r/min for 3 h has relatively high purity and crystallinity. Mg-A1 LDHs synthesized in this study have large particl size and poor crystallinity. Its thermal behavior is different from that of the Mg-A1 LDHs reported, which may be related to the higher Mg and lower A1 in its composition.