HYDROTHERMAL SYNTHESIS OF AMMONIUM ILLITE

Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starling materials for hydro thermal synthesis of ammonium illite. Ammonium illite was prepared fro m synthetic gel by hydrothermal treatment at 300 degrees C. The onset of crystallization began within 3 h, and well-crystallized ammonium il lite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent prop ortions of potassium and ammonium, the gel was transformed to illite w ith equimolar contents of K and NH4. In contrast, synthesis using glas s under the same conditions resulted in a mixture of mixed-layer ammon ium illite-smectite with large expandability and discrete illite. Hydr othermal treatments of the fine fractions of natural kaolinite and ill ite-smectite produced ammonium illite from kaolinite but the illite-sm ectite remained unchanged.