日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

For efficient utilization and addition of value for doatomite resources in Akita Prefecture, we have developed a decreasing process of inherent iron contained in the Moriyoshi diatomite ore with help of organic acids. Modifying the surface of acid-treated diatomite shell by preparation of zeolite, we are evaluating possible characteristics for a diatomite filter-aid which has adsorption capacity.

Some experimental results are introduced of preparation of NaA zeolite by reacting Al and Na ions and H₂O on the surface of amorphous silica obtained through calcination of original ore at 650°C for 2hrs after treating with warm oxalic acid.

By adjusting the atomic ratios of Al and Na, (0.25～0.42), (0.5～0.7) and the mole ratio of H₂O, (10～42) to reactant silica, a slurry was served in a batch stirred vessel for observation of crystallization and growth of NaA zeolite on the silica surface at (50～80)°C for (4～48)hrs. Crystallization rate, evaluated by change in crystallinity with time, increased with reaction temperature and especially in the initial reaction-time region with comparison to the case of sodium silicate reagent as a starting material. Internal surface area of produced solid and its adsorption capacity of carbon dioxide changed uniquely as crystallization progressed.