화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.14, No.7, 927-931, November, 2003
규산나트륨과 플루오르화 규소산을 이용한 층상 실리케이트의 합성
Syntheses of Layered Silicate from Hydrofluosilicic Acid and Sodium Silicate
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초록
플루오르화 규소산과 규산나트륨의 중화반응으로 생성된 실리카 슬러리를 실리카 원료로 이용하여 Na-magadiite와 Na-kenyaite를 합성하였다. 반응은 다양한 조성, 온도, 시간의 변화를 주면서 수열조건에서 수행되었다. 반응시간이 증가함에 따라 무정형 실리카 → Na-magadiite → Na-kenyaite → Quartz의 순서로 결정의 상변화가 일어났으며, 상변화는 온도의 증가에 의해 더욱 촉진되었다. 특히 SiO2/Na와 H2O/Na의 낮은 몰 비에서는 무정형 실리카로부터 magadiite 결정이 형성되는 반면, 높은 몰 비에서는 무정형 실리카로부터 kenyaite 결정이 직접 형성되었다. 위의 결과들은 실리카 원료로서 가장 저렴한 규산나트륨과 인산비료 공정의 부산물인 플루오르화 규소산을 이용하여 결정성 좋은 Na-magadiite와 Na-kenyaite의 제조가 가능함을 보여주었다. 이러한 합성방법은 Na-magadiite와 Na-kenyaite의 경제성 있는 대량생산 공정에 효과적으로 적용될 수 있으리라 본다.
Na-magadiite and Na-kenyaite were synthesized from the silica slurry obtained by the neutralization reaction between hydrofluosilicic acid and sodium silicate solution. The crystallization was carried out under hydrothermal condition at various compositions of reactants, reaction temperature, and reaction time. As reaction time increase, amorphous silica was converted into Na-magadiite, which, in turn, was continuously converted into Na-kenyaite. Finally, Na-kenyaite converted to quartz. Phase transformation was accelerated with the increase of temperature. Particularly, amorphous phase is directly converted into Na-kenyaite without the formation of magadiite as an intermediate in the case of high mole ratios of SiO2/Na and H2O/Na. The results show that Na-magadiite and Na-kenyaite were well-synthesized under hydrothermal condition using relatively cheap sodium silicate and hydrofluosilicic acid as silica sources. The hydrofluosilicic acid can be easily obtained from the by-product in the manufacturing process of phosphoric acid. This synthetic method can be easily obtained from the by-product in the manufacturing process of phosphoric acid. This synthetic method can be adopted as one of the effective commercial process.
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