Ehance Manufacture And Characterization Of Nanometer Gluconic Acid Montmorillonite

Alkaline clay is anion exchange bentonite which has been developed by our research group. Active hydroxide groups on the surface and in the layer of alkaline clay can react with many organic acids to make the organic grounps get into the layers of clay. Organic acids, which are abundant in nature, can be employed to modify alkaline clay to get a variety of organic acid bentonites. Gluconic acid is a polyhydroxy organic acid, and can modify alkaline clay to make a polyhydroxy bentonite which has excellent hydrophilicity and compatibility with polyhydroxy polymer.Gluconic acid clay have good compatibility with glycerin and can disperse in glycerol stably, which makes the sedimentation under high-speed centrifugation is difficult. However, gluconic acid clay have bad compatibility with ethanol and the sedimentation of gluconic acid clay in the suspension of ethanol solution by centrifugation becomes easy. Therefore, raw gluconic acid clay can be disperse in a mixed solution of ethanol and glycerol with certain ratio, by which particles with large size, not the gluconic acid clay, are removed by centrifugation. The remainder suspension is collected and added with ethanol to reduce the compatibility of gluconic acid clay, and the high-purity gluconic acid clay is obtained after centrifugation.Gluconic clay possessing good affinity with water-soluble polymers was prepared via organic modification of alkaline clay by gluconic acid. Single factor analysis was employed to study the influence of the amount of gluconic acid, solvent, the reaction time, the amount of of glycerin, rotate speed on the preparation of gluconic acid clay. The experimental results showed that gluconic acid clay with36%of organic degree was achieved when5.0g of alkaline clay reacted with3.0g gluconolactone in100mL of70%ethanol under400r· min-1of rotate speed for2h.Ethanol-glycerin system was used to purify gluconic acid clay and the purified gluconic acid clay was applied for the preparation of PVA film. The refined product which was purified with50%of glycerol-ethanol solvent and3000r· min-1of centrifugation is best. This purified gluconic acid bentonite was applied in PVA film as nanometer filler, and the tensile strength and breaking elongation of films were enhanced62%and30%respectively when the addition amount was2%, which indicates the mechanical properties of blending film was increased significantly.