摘要
通过研究Ca2+、Al3+、H+饱和的蒙脱石,Ca2+饱和的叶腊石和高岭石对水溶液中两种有机碱(甲基黄和S3307D)的吸附反应,证实了粘土矿物-有机碱吸附作用机制中表面酸碱反应的存在及其重要性.粘土矿物对有机碱的吸附能力为H+-蒙脱石 Ca2+-叶腊石>Al3+-蒙脱石 Ca2+-蒙脱石≈Ca2+-高岭石.通过测定悬浮液pH值和水溶液中矿物表面酸强度,判断吸附机制主要是由表面酸强度而非pH值所控制,即吸附反应机制主要为矿物表面酸位与有机碱之间直接的表面酸碱反应.水溶液中可能的粘土表面酸位为交换性Al3+、H+以及2∶1型矿物表面不带电荷部分.
The occurrence and importance of acid-base interaction between clay minerals surfaces and two organic bases, l-(4-chlorophenyl)-4, 4-dimethyl-2-(lH-l, 2, 4-tria-zol-l-yl) penten-3-ol and N, N-dimethyl-4-(phenylazo )-benzenamine in the adsorption processes were studied. A montmorillonite saturated with Ca2+, Al3+, H+, a pyrophyllite and a kaolinite saturated with Ca2+ were selected as adsorbents. Adsorptive affinity for the triazol derivative is in the order: H+-montmorillonite Ca2+-pyrophyllite>Al3+-montmorillonite Ca2+-montmorillonite Ca2+-kaolinite. The surface acidity of Al3+, H+-montmorillonite and Ca2+-pyrophyllite in aqueous solutions was found to be much lower than the suspension pH and it is sufficient to enable the protonation of the base at the mineral's surfaces. S3307D is significantly adsorbed from aqueous solutions by mineral samples only when the surface acidity of the mineral is near or lower than the pKa. Visible light absorption spectra show that the methylyellow changes from basic form (yellow) to acidic form (red) when surface acidity of minerals is near or lower than the pKa. These results indicate that acid-base interaction between the organic bases and surface acid sites on clay minerals may significantly contribute to adsorption process. The clay mineral's surface acidity in aqueous solution may originate from exchangeable H+, Al3+ and uncharged siloxane surface.
出处
《上海交通大学学报》
EI
CAS
CSCD
北大核心
2004年第11期1939-1942,共4页
Journal of Shanghai Jiaotong University
基金
上海交通大学985项目(113416000)
2002年度教育部留学回国人员科研启动基金项目
