Investigation of CaCO₃ crystallization induced by extracellular polysaccharide

Calcium carbonate was prepared by the CaCl₂-Na₂CO₃ solution in the presence of xanhtan gum and welan gum as template. The interaction between extracellular polysaccharides and Ca²⁺ was confirmed by the method of conductivity. The effects of concentration of xanthan gum and welan gum, crystallization time on the morphology of calcium carbonate were also studied, respectively. The products were analyzed by FT-IR, XRD and SEM, respectively. The results showed that calcium carbonate prepared in xanthan gum and welan gum solution were the mixture of calcite and vaterite. Products in welan gum solution were spherical. Spherical and flower-like calcium carbonate particles were obtained in xanthan gum solution. The vaterite gradually transformed to calcite with the time.