Preparation Of Biomimetic Calcium Carbonate By Using Egg-white As Template And Its Adsorption Performance

With the development of biomineralization research,people have realized that organic and inorganic metal ions play a key role in the morphology and structure of mineralization products,and have done a large number of fruitful works in this field.However,there are still many deficiencies,for example,the method of biomimetic mineralization is still unable to accurately simulate the natural biomineralization process,the type of metal ions having been studied is very limited,and the biomimetic mineralization is out of step with the practical application.For solving the problems mentioned above,using Ca CO₃ as the research object of biomimetic synthesis and egg-white as the template,we have systematically studied the method of gas-liquid interface assembly and the interaction between Sr²⁺ and Cs⁺ and the mineralization process of Ca CO₃.The results of this study have some advantages,including complementing the existing methods of biomimetic mineralization enriching the biomineralization mechanism,and providing a new idea for the treatment of low radioactive wastewater.The prime contents are as follows:?1?The homogeneous submicron spherules of Ca CO₃ were prepared using egg-white foam as a template by a gaseous diffusion method.The influences of volume ratio of egg-white and Ca Cl2 solution along with Ca²⁺ concentration on the morphology and crystal of Ca CO₃ were investigated.The adsorption properties of Ca CO₃ on Sr²⁺ were studied.The morphology,crystal form and specific surface area of CaCO₃ were characterized by scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,high resolution transmission electron microscopy and BET surface area analyzer.The results show that egg-white foam has the best stability when the volume ratio of egg-white and Ca Cl2 solution is 2:1.When Ca²⁺ concentration is 1 mol/L,the homogeneous of vaterite are prepared.After adsorption experiment for 36 hours,the adsorption capacity of CaCO₃ reaches saturation?51.36 mg/g?.Furthermore,the growth mechanism of mineralization and adsorption mechanism of Ca CO₃ were discussed.?2?CaCO₃ were prepared using egg-white as a template and mixing Sr²⁺ or Cs⁺ as additive by a gaseous diffusion method and a direct precipitation method.The influences of Sr²⁺ and Cs⁺ on the morphology and crystal of Ca CO₃ were investigated.We further investigated the effects of Sr²⁺ concentration,incomplete direct precipitation,Cs⁺ concentration and mineralization time on the adsorption rate.The morphology and crystal of Ca CO₃ were characterized by scanning electron microscopy,X-ray diffraction and Fourier transform infrared spectroscopy.The results show that Sr²⁺ is conducive to the formation of needle-like aragonite only in the presence of egg-white.The adsorption rate of Sr²⁺ is increased with the increase of Sr²⁺ concentration in the mineralization process,and reached the maximum at the concentration of Sr²⁺ is 100 mg/L.The adsorption rate of the CaCO₃ prepared by direct precipitation method on Sr²⁺ is significantly higher than that of gas diffusion method.Under the presence of egg-white,the low concentration of Cs⁺ is in favor of the formation of calcite,while high concentration of Cs⁺ is conducive to the generation of vaterite.With the increase of Cs⁺ concentration,the adsorption rate of Cs⁺ increased firstly and then decreased in the mineralization process and decreased with the extension of mineralization time.