| As the natural halloysite uneven distribution, less occurrence, poor mining conditions and large difference in morphology between different areas, Costanzo proposed to synthesize 10?-halloysite (viz. 10? kaolinite hydrate) from kaolinite. The most common methords of synthesizing hydrate are Costanzo method and Raythatha method, and the most obvious difference between them is whether ammonium fluoride will be added. In order to explain this difference and to further understand the mechanism of hydration of kaolinite, this work detailed and compared every step of two methods, it was found that every factor (except the quantity of ammonium fluoride) in the hydration process had similar impacts on two methods, but the Costanzo reaction generated more other products, and with the increase of ammonium fluoride, hydrate production decreased; according to the molecular simulation results author concluded that the adding of ammonium fluoride was not necessary in the hydration process of kaolinite; at the same time the optimum technics within the scope of the current experiment was gained to produce 10? hydrate with a yield high to 91%.Based on the study of the KD complex reaction with methanol and water respectively, and the results about two different methods, the hydration mechanism was proposed: DMSO molecules in KD complexe had at least three types, the restriction caused by kaolinite layers on each type and the speed removed from interlayer space were different, so water molecules would be absorbed on interlayer space, then the collapse of kaolinite layers stood by the interlayer water molecules resulting in a more stable 10? hydrate.In order to investigate the structure of 10? hydrate or 10?-halloysite, molcular dynamics method was used in simulating the arrangement of interlayer waters, the results showed that in addition to the hole water (type I) and connecting water (type II), there was also another water molecule, which almost keep vertical in interlayer space(type III); these three water molecules mainly arrange in I-III or II-III form alternately.By means of TEM observation, not only the curling along the single side, along the opposite sides were found, but also the curling along the adjacent sides,; further selected area diffraction analysis showed that the direction of these curling contain other orientations than a axis and b axis; the analysis of kaolinite structure revealed the degree of easiness to curl for all current orientations was [110]>[010] =[310] = [3-10 ]>[100]>[1-10].The cause of several disorders in kaolinite were clarified by means of analysizing of kaolinite structure; by means of study on the substitution of fluorine for interlayer hydroxyl in kaolinite crystal, the changing behavior of structure disorder was gained as the hydrogen bond was weakened; by means of analysizing the changing behavior of structure disorder in a single kaolinite layer the similar trend to the periodic system was gained for the changing of these disorders; tetrahedral bend and tetrahedral rotation might played the major roles in curling process, therefore author thought Singh's interpretation about the curling mechanism of kaolinite layer to be correct in some extent.In order to test whether the substitution Fe for octahedral Al would cause the flattening of curling halloysite, gibbsite and kaolinite with different content of Fe were studied with the energy minimization method. The result showed there was a limit range of Fe substitution, the calculated radius of halloysite increased with the improvement of Fe substitution in the range, which revealed Fe substitution for octahedral Al could alleviate the dismatch of kaolinite 1:1 layer certainly, and the affect of Fe substitution on tetrahedral rotation and tetrahedral corrudation also indicated this point. Thus author thought whether the flattening of halloysite could be attributed to iron substitution, the key was whether the substitution of iron was easy to happen.The dissertation includes 110 figures, 21 tables and 252 references.
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