Preparation of single-phase aragonite precipitated calcium carbonate used as an inorganic eco-material

In this study, single phase aragonite PCC was synthesized by the solution process using Ca(OH)(2) slurry and Na2CO3 solution as the main reactants. To begin with, the formation behavior of PCC polymorphs following changes in supersaturation was investigated, and the optimum synthetic condition of single-phase aragonite PCC was clarified after the role of NaOH in the reaction system was reviewed. In the results, it was considered that lower supersaturation was necessary to obtain a single phase aragonite; and, since the solubility of Ca(OH)(2) was decreased with the addition of NaOH by a common ion effect, it is possible to perform a experiment at a lower Ca2+ concentration. In conclusion, in the case of the reaction of the 2.5M NaOH solution, single phase aragonite was obtained. Furthermore, NaOH solution was produced as a by-product in the solution process by reacting Ca(OH)(2) slurry with Na2CO3. Thus, recycling of the NaOH solution was attempted in order to clear the environmental issue. It is difficult to recycle directly since the NaOH solution was diluted during the experiment. The optimum condition was investigated by control of experimental factors such as the concentration of Ca(OH)(2), Na2CO3 and NaOH, and the reaction temperature, after which the NaOH solution was recycled without re-treatment. The formation characteristics of aragonite PCC, such as formation yield, particle morphology and aspect ratio, were investigated.