Preparation And Application Of The Intercalated Kaolinite And Hydrated Kaolinite

Kaolinite is a common industrial raw material, widely used in papermaking, ceramics, rubber, plastics, coatings, medicine and many other fields. In recent years, the organic-inorganic hybrid materials with excellent performance could be prepared by the intercalation technique of kaolinite, these materials have vast application prospects in many new areas and have attracted growing interest. However, only some small polar molecules could be intercalated because of the strong hydrogen bonds between the adjacent layers. Most of kaolinite organic intercalation compounds need to be prepared by guest-replacement intercalation method. So it is important to find an efficient, broader applicability intercalation precursor. Some researches have found that the hydrated kaolinite could be acted as a new environment-friendly intercalation precursor. The common preparation methods of hydrated kaolinite need three-step replacement intercalation. Preparation of hydrated kaolinite by using direct intercalated kaolinite compounds could simplify the preparation process, and greatly promote the new application of hydrated kaolinite. In addition, kaolinite organic intercalation compounds are often used in exfoliation, and the single nanosheets of kaolinite have great value for preparing the polymer/layered silicate nanocomposites.Based on a large number of literatures, this thesis reviewed the development and application of kaolinite organic intercalation compound. Besides, the various preparation methods of hydrated kaolinite and exfoliation of kaolinte were summarized. The researches were about the preparation of hydrated kaolinte by using urea/kaolinite and hydrazine/kaolinite intercalation compound as intermediates, and the main contents and conclusions are as follows:In this thesis, the urea/kaolinite intercalation compound was prepared by grinding and subsequently heating treatment of kaolinite and urea, with the intercalation ratio of 89.4%, and the hydrazine/kaolinite compound was prepared by liquid intercalation with the intercalation ratio of 98.4%. Meanwhile, the hydrated kaolinite was prepared with simple direct displacement intercalation method by using urea/kaolinite compound as an intermediate, the grain thickness of kaolinte reduced from 25 nm to nearly 8 nm during the acid treatment. And the highest content of the doo1=0.85 nm hydrated kaolinite appeared at high temperature, which was nearly 64% by washing with water at 90℃. And the doo1=0.84 nm hydrated kaolinite was obtained when the hydrazine/kaolinite compound was heated at 60℃for 2h, with the content nearly 80%. The ethylene glycol/kaolinite intercalation compound could be prepared by the intercalation of hydrated kaolinite with ethylene glycol, indicating that the hydrated kaolinite derived from these two methods have further intercalation ability, and may become an excellent precursor for preparing other kaolinite intercalation compounds. In addition, the exfoliation process was carried out by the reaction of hydrazine/kaolinite with hydrogen peroxide, and after the dispersion and deposition treatment with surfactant, the single layer structure of nanosheets and nanotubes could be obtained from the suspension.