Electrolytic Method For Synthesis Of Al、Mg Metal Alkoxide And Study On Characterization Of Hydrolysate

In this dissertation metal alkoxide have been prepared by electrochemical process withinert electrode as cathode, pure aluminium and magnesium as anode, and the alkoxidesolution was changed into ultra-fine powder with different morphologies and differentmicrostructure properties by the sol-gel, hydrothermal treatment process. During thepreparing process the optimal conditions of the electrolysis reaction and effects of alcohol-water ratio, Hydrolysis temperature, hydrothermal temperature, hydrothermal time andprecipitant concentration on products were investigated systemically by SEM, XRD and Sizeanalysis.The results indicate that, to avoid anode passivation and improve the electrochemicalsynthesis efficiency, electrolysis temperature was controlled at40~50℃, and theconductive salt concentration was controlled at0.04~0.05mol/L.Without hydrothermal treatment condition, whether the aluminum alkoxide ormagnesium alkoxide, the hydrolysis products of them are hydroxide with irregularmicrostructure. When the hydrolysis temperature is at20°C and alcohol-water mol ratio is1:3and1:2, center size of the powders obtained after the hydrolysis of aluminum alkoxideand magnesium alkoxide solution is smaller and particle size distribution is relativelywell-distributed.After process of hydrolysis which is under hydrothermal conditions without precipitant,the product from magnesium alkoxide solution is still magnesium hydroxide, but the grainsize is refined, and showing the laminate structure, With the rasie of alcohol-water mol ratio,the grain size is larger. when the Hydrothermal temperature reaches160℃with urea as aprecipitating agent, the product is magnesium carbonate Under such conditions, and with therasie of the hydrothermal time, the product gradually transformed into cube small particlesfrom irregular blocks, but when the Hydrothermal temperature reaches200℃, the product isstill magnesium hydroxide with irregular morphology.The mechanism of crystal growth and kinetic analysison was analyzed and discussed indetail. It shows that about thermal decomposition process of anhydrous magnesiumcarbonate,the most probable kinetic model is G-B and eq.a mechanism, and its growthmechanism is comply with the dissolution-crystallization mechanism...