Synthesis of Dawsonite (Basic Sodium Aluminum Carbonate) from Colloidal Earth (Aoolphane) by Treatment with Acid and Alkali

[摘要] Aoolphane was treated with 30% Hydrochloric acid at 18¡É for two hows with stirring in order to obtain the insoluble form of SiO2 gel and to extract quantitatively both Al2O3as and Fe2O3AlCl3¡¤6H2O Fe and Cl3¡¤6H2O forms, respectively, at the same time. SiO2 gel was filtered and to the filterate Ammonia was added to precipitate Al(OH)3[Fe(OH)3 Contaminated ] The precipitate was separated by filteration and the filterate was recovered as the form of NH4Cl. The precipitate was treated with 200g (NaOH)/l Concentration of NaOH a little excessively to the equivalent at 65~70¡É as Fe(OH)3 formed was insoluble, it was filtered of and to the filterate containing NaAl(OH)4(OH2)2Carbon dioxide gas was bubbled at 50¡É~90¡É to obtain the precipitate with excellent filterability and crystallinity. The product was certified to be Dawsonite (NaAl(OH)2CO3) by X-Ray diffraction analysis at below 40¡É, when CO2 gas was bubbled into the relatively lower concentration of NaAl(OH)4(OH2)2 solution, the precipitate of very fine particles was formed, which was hard to filter and with the Composition of ¥á-Al2O3-H2O (Boehmite).

[学科分类] 化学（综合）