Organic Anion Pillared Hydrotalcite Preparation And Structure And Performance

This thesis relates to a systemic study on the preparation of organic-anion-pillared hydrotalcites by intercalation and assembly through carbonate hydrotalcites, and on the relationship between the composition, the structure and the property of the products thereby obtained. A preliminary investigation has also been carried out on the synthesis of a slow-releasing pesticide as one of the practical applications of the organic-anion-pillared hydrotalcites.We have systemically investigated the dependence of the intercalation on such reaction conditions as pH value, temperature, molar ratio and solvents, as well as the influence of the composition of the brucite layers and the organic anion guests. The results show that, by controlling the reaction conditions, a series of organic-anion-pillared hydrotalcites can be successfully obtained by anion exchange through carbonate hydrotalcites. Compared to the other methods, preparation by anion exchange at an acid condition is more convenient for manipulating and designing, and needs shorter time and a lower molar ratio.The crystal structure and outward appearance, IR property and thermal stability of the organic-anion-pillared hydrotalcites have been studied by XRD, TEM, FTIR and TG-DTA. The results show that the organic-anion-pillared hydrotalcites, with a high degree of anion exchange, have similar crystal appearances to their precursors. The interlayer distance depends on the arrangement of the organic anions, as well astheir size. The arrangement of the organic anions is influenced by the amount of the interlayer water molecules, the composition of the brucite layers and the degree of anion exchange. The thermal stability of the pillared hydrotalcites varies regularly with the amount and the structure of the interlayer organic anions.The synthesis of the slow-releasing pesticide, glyphosate-pillared hydrotalcite, has been carried out by anion exchange and coprecipitation respectively. Compared to that obtained by the coprecipitation method, the sample obtained by anion exchange has a higher crystallinity.