Studies on the Preparation of Aragonite (I). Formation of Aragonite of Pillar Shape

$Sr(OH)_2$ 가 소량 첨가된 수산화칼슘 수용액에 $CO_2$ 가스를 흡수시켜 탄산화 반응을 행하였으며, 이 반응에서 반응온도와 $Sr(OH)_2$ 가 탄산화반응에 미치는 영향을 조사하였다. 주상형의 aragonite는 반응온도가 높을수록, $Sr(OH)_2(aq)/Ca(OH)_2(aq)$ 의 비가 클수록, 즉 $OH^-/CO_2(aq)$ 의 비가 클수록, 잘 생성되었다. $Sr(OH)_2$ 는 탄산화반응 초기에 aragonite와 유사한 사방정형의 $SrCO_3$ 를 쉽게 형성하고, 물에 대한 용해도가 높기때문에 $OH^-$ 이온을 증가시켜 용액내에 결정성장에 유리한 $CO_3^{2-}$ 이온을 보다 쉽게 형성시키므로 주상형 aragonite 생성에 유리한 역할을 하였다. 【An aqueous solution of $Ca(OH)_2$ containing a small amount of dissolved $Sr(OH)_2$ was carbonated with $CO_2$ gas, and the effects of the reaction temperature and $Sr(OH)_2$ on the carbonation were investigated. The higher the reaction temperature and the larger the ratio of $Sr(OH)_2(aq)$ to $Ca(OH)_2(aq)$ , which amounts to the larger the ratio of $OH^-$ to $CO_2(aq)$ , the better pillar aragonite was formed. $Sr(OH)_2$ played an important role in the formation of pillar aragonite, because it is easily formed itself into rhombic $SrCO_3$ during the initial period of carbonation process and acting as a seed for the pillar aragonite of similar morphology. In addition, due to its substantially higher solubility compared with $Ca(OH)_2$ , $OH^-$ concentration in the carbonation mixture and subsequently $CO_3^{2-}$ necessary for the crystal growth are increased.】