超细氢氧化铝粉体干燥过程中表面活性剂的作用机理

Agglomeration mechanism of surfactant of ultra-fine Al(OH)_3 in drying process

基于超细氢氧化铝粒度分布曲线和红外光谱，通过粒子数计算和3700～3000cm^-1间红外光谱分峰拟合，研究了干燥过程中表面活性剂对超细粉体粒度的影响规律。结果表明：加入表面活性剂后，干燥后超细氢氧化铝粒子总数的减少不大于6％；而不加表面活性剂时，粒子总数减少99．98％；同时可能是由于粒度小于0．1μm的粒子易吸附于表面活性剂的原因，干燥过程中的团聚程度较小，而粒径为0．5～10μm的粒子团聚较明显。红外光谱分析结果表明：加入表面活性剂A和B后，在1310cm^-1处出现游离O-H特征峰，同时游离的O-H从32．3％（质量分数）分别增加至39．88％和35．95％，多分子间缔合的O-H特征峰从36．65％分别减少至29．78％和27．79％；这说明表面活性剂的加入可以明显抑制分子间O-H的形成，从而可降低粒子的团聚程度。

The influence of surfactant on the particle size and agglomeration mechanism was studied in term of the particle numbers calculated from particle size distribution and multi-peak fitting of IR spectra. The results show that the particle number reduces less than 6% with addition of surfactant, while that reduces 99.98% without adding surfactant. The coarse particle （0.5-10μm） is much easier to be agglomerated than the ultra-fine particle（less than 0.1μm）, which maybe due to the easy absorption of surfactant for the ultra-fine particle. The results from IR show that the characteristic peak appears at 1 310 cm^-1 accounting for flee O--H when surfactant is added, and then free O--H increases from 32.30% （mass fraction） to 39.88% and 35.95%, respectively, and O--H in association molecular reduces from 36.65% to 29.78% and 27.79%, respectively. This shows that the agglomeration is inhibited by reducing the amount of O-H in association molecules with addition of surfactant in the drying process.