Growth and Nucleation of Calcium Carbonate Vaterite Crystals in Presence of Alginate

Structural biocomposites found in nature often have a well-defined organization on the nanometer scale. For mineralized materials, interactions between organic and inorganic phases are important for controlling crystal size, morphology, and spatial arrangement, which is a requirement when structural biomaterials are designed. In this paper, we studied influence of low concentrations of alginate on calcium carbonate crystallization by seeded and unseeded experiments, at controlled activity-based supersaturations. Crystal growth and nucleation were characterized by scanning electron microscopy (SEM), calcium concentration measurements, and crystal volume distribution measurements through the crystallization experiments. Alginate concentrations as low as 10 ppm were found to have a significant effect on growth of vaterite seeds, resulting in decreased growth rates and extensive agglomeration, compared to the case without alginate. For increased alginate concentrations (100 and 200 ppm), vaterite seed growth ...