蒙脱石与土酸、多氢酸反应对比实验研究

Comparative Experimental Study on Reaction of Montmorillonite with Mud Acid and Multi-Hydrogen Acid

祖凯郭建春

ZU Kai GUO Jian-Chun

对比分析了常规土酸和多氢酸与水敏性矿物蒙脱石的反应，研究了蒙脱石在两种酸液体系中的溶蚀率和沉淀规律，反应后残酸溶液中的硅、铝离子浓度，并用扫描电子显微镜观察了反应后蒙脱石表面的微观结构变化。结果表明，30℃、90℃下，多氢酸对蒙脱石的溶蚀率小于常规土酸，90℃下蒙脱石与土酸反应产生二次沉淀。多氢酸与蒙脱石反应后，在蒙脱石表面生成铝-硅-磷酸盐“保护膜”。该“保护膜”在弱酸中的溶解性较差，但可迅速溶解于盐酸中。随反应时间的延长，土酸与蒙脱石反应后残酸中的硅离子浓度先增加后降低、铝离子浓度逐渐增加，而多氢酸与蒙脱石反应后残酸中的硅、铝离子浓度均增加，表明多氢酸对金属离子具有较强的吸附和螯合能力。图5表1参5

The reactivity of mud acid and multi-hydrogen acid on the water-sensitive montmorillonite mineral was analyzed comparatively,and the dissolution rate and precipitation law of montmorillonite in the two acid systems were studied.At the same time,the concentration of Si4+,Al3+ in the residual acid was investigated.Microcosmic transformation in the structure of montmorillonite was observed by scanning electron microscopy(SEM).The experiment results showed that the dissolution rate of multi-hydrogen acid on montmorillonite was less than mud acid at 30℃ and 90℃.It would form secondary precipitates after the reaction of montmorillonite and mud acid at 90℃.When the multi-hydrogen acid reacted with montmorillonite,one aluminum-silicate-phosphonate plating formed over the surface of montmorillonite,which had low solubility in weak acids but could be rapidly dissolved by HCl.With increasing reaction time,the concentration of Si4+ in the residual acid increased at first and then decreased and that of Al3+ increased gradually after the reaction of mud acid and montmorillonite.Meanwhile,the concentration of Si4+,Al3+ in the residual acid both increased after the reaction of multi-hydrogen acid and montmorillonite.It indicated that the multi-hydrogen acid had a strong ability of absorbing and chelating to metallic ions.