Biomimetic mineralisation of calcium carbonate using xanthan gum as morphology control agent

Biomimetic synthesis of calcium carbonate (CaCO3) with various sizes and morphologies using organic matrix has become an interesting hotspot. CaCO3 was synthesised by the reaction of Na2CO3 and CaCl2 in the presence of xanthan gum (XG). The results showed that the fresh mineralised CaCO3/XG were microspheres with large surface area and porosity. The original CaCO3/XG microspheres transformed to brick-like CaCO3 after ageing 7 days at 4 degrees C. During the morphology transformation, CaCO3 spheres rearranged by attaching to XG molecular, and transformed from a macroscopic view of CaCO3 microspheres to a hexahedral structure related with the XG uncoiled single chains re-associating into loose several-fold helix. The study demonstrated that environmental effect coupled XG could be one feasible approach to regulate the structure of CaCO3.