Study On The Biomimetic Synthesis Of Nacre In Vitro And The Reparation Of Inferior Southern Pearls In Situ

The study used the seawater pearls produced in the Liushawan area as the research object.The gas diffusion method,liquid phase method,and gas-liquid combination method were adapted to conduct bionic research in vitro about calcium carbonate biomineralization and to find the main factors that affect the formation of nacreous calcium carbonate crystals and new methods in situ bionic modification which realize high-value.To simulate the growth process of pearls in mother-of-pearl,the whole study was carried out in a closed container.The effects of different types of amino acids on the calcium carbonate mineralization process and the synergistic effects of various organic and inorganic substances on the calcium carbonate crystal form were studied.Finally,we focused on the study of the law of influence of Mg²⁺and Sr²⁺on the biomimetic synthesis of seawater-like pearlite under the combination of sodium alginate and amino acids,and the different calcium-strontium ratios against seawater-like pearlite under the synergistic effect of chitosan membrane and sodium alginate membrane.In this study,infrared spectroscopy?FT-IR?,X-ray diffractometer?XRD?and scanning electron microscope?SEM?were used to characterize and analyze the obtained samples,and photoelectron spectroscopy?XPS?was used to analyze the samples.The research results are summarized as follows:?1?Study on preparation of pearl-like bionic materials induced by amino acid.The results showed that acidic amino acid have better effects on inducing aragonite and vaterite,of which aspartic better on acid-inducing aragonite,and glutamic better on acid-inducing vaterite.Neutral amino acid have weak effects on inducing calcium carbonate,and tyrosine and serine are superior to cysteine and glycine.With the increasing concentration of amino acids,it enhanced the crystallization of aragonite and vaterite.When the concentration of calcium chloride increases,the volume of calcite crystals increases significantly,and the crystals structure is more orderly,while it has a weak inhibitory effect on aragonite and no significant effect on vaterite.?2?Study on the biomimetic synthesis of seawater-like nacre by Mg²⁺,Sr²⁺under the synergistic effect of sodium alginate and amino acid.The results show that after the sodium alginate solution was added with amino acid solutions of equal concent ratio and different amounts,the crystal form of calcium carbonate is close to calcium carbonate crystals of inferior seawater pearls which are different from the aragonite crystal in the nacreous layer of high-quality seawater pearls.The addition of Mg²⁺and Sr²⁺both affect the morphology of calcium carbonate crystal.In comparison,Mg²⁺is more likely to induce the formation of lamellar aragonite,while Sr²⁺is more likely to generate massive calcite and spheroidal aragonite.?3?Study on the biomimetic synthesis of seawater-like nacre by different calcium-strontium ratio under the action of chitosan film and sodium alginate film.The results show that when sodium alginate film is used as induced template,it is easier to induce the formation of calcium carbonate crystals.And the crystal arrangement is more regular and denser,but it mainly generates calcite crystals which are close to the composition of inferior seawater pearls.On the contrary,the chitosan film is easier to induce the forming of aragonite crystals,which is close to the composition of high-quality seawater pearls.When the inducers are different,there are differences the types,sizes and arrangement of crystals induced by same calcium-strontium ratio solutions.When the inducers are the same,along with the added calcium ion decrease and the strontium ion increases,the size of the obtained calcium carbonate crystals will decrease,and the arrangement is regular and close,in which the crystal layer stacking method is close to the structure of the nacreous layer.?4?Study on the reparation of inferior southern pearls in situ.Two or more additives can be added during the reparation of residual southern pearls,at which the ability to induce calcium carbonate crystallization is enhanced,and the effect of repairing residual southern pearls is better.And by extending the reaction time,the repair effect can be enhanced.In the process of repairing southern pearls,when the calcium ion with a lower concentration is added,and the calcium ion concentration in the system is kept as constant as possible,the growth environment of the pearl to be better simulated and the repair effect better.For other metal ions,it is necessary to study their influence on the morphology of calcium carbonate crystals early to determine the amount of addition.