Covering of nanometric calcite with α-cyclodextrin

In the present experiments, the monodisperse calcium carbonate nanoparticles obtained in the reactor (three-phase reaction) with rotating discs have been covered with alpha-cyclodextrin. Both pure CaCO3 nanoparticle and alpha-cyclodextrin-coated CaCO3 powders were deeply analysed by the use of the scanning electron microscope, the dynamic light scattering and the thermogravimetric method. The experimental data have allowed for determination of effective diameter of the obtained particles (aggregates of ca. 30 nm single crystals) and their size distribution (almost monodisperse-ca. 390 nm) as well as for distinction between alpha-cyclodextrin molecules present on calcite surface or free alpha-cyclodextrin molecules if presented in the sample. It was found that the nanometric CaCO3 obtained in the reactor with rotating discs can be covered with a maximum of 1.15% alpha-cyclodextrin monolayer. The maximal coverage of the CaCO3 calcite particles with alpha-cyclodextrin can be done by 24-h shaking of 50 mg nanometric calcium carbonate with 25 mg of 36.79 mM alpha-cyclodextrin aqueous solution.