The Effect Of Several Amino Acids On The Crystallization Of CaCO₃

Calcium carbonate is one of the most common biominerals in nature,non-hydrated calcium carbonate has three polymorphs, calcite, aragonite and vaterite.This subject on the basis of previous research, further study of the impact of thealkaline and neutral amino acids on the calcium carbonate mineralization, trying tofigure out the impact of the different amino acids carried by the R group of calciumcarbonate mineralization, in order to improve the amino acid on calcium carbonatetheoretical study of the mineralization. At the same time, in vitro calcium carbonatemineralization, diffusion and gel method in two different systems and trying tofigure out the impact of the different systems of calcium carbonate mineralization,and amino acids on the mineralization of calcium carbonate with different systemchanges.It’s in order to improve the mineralization of calcium carbonate in vitrosimulation.Through the design of experiments to complete the experiments and analysis ofthe experimental results of characterization, the following conclusions:1、A neutral or basic amino acids in aqueous solutions of pH values rangingfrom its isoelectric point （pl values） will bring a different charge, so will themineralization of calcium carbonate have an impact. The pH values greater than thepl value of the amino acid, amino acids release protons and thus a negative charge,then negatively charged amino acids will attract Ca²⁺ions, making the local ionconcentration, local supersaturation, promoting the mineralization of carbonatecalcium. The pH values less than the pl value of the amino acids, amino acidsprotonated and thus bring a positive charge, the same, with the positively chargedamino acids will attract the CO₃^2-ion, the solution of partial reach saturation, thuscontributing to the mineralization of calcium carbonate. Hydrophobic non-polaramino acid in the water did not understand from and R groups, the mineralization ofcalcium carbonate had no effect. At the same time, the concentration of amino acidchanges will affect the amount and size of the mineralization product.2、 The mineralization of calcium carbonate in the diffusion method, as the Ca²⁺ions in aqueous solution in the first preliminary and different amino acids, andthen the formation of different seed template （ligand）, and then the guidance fromthis template effect CO₃^2-ions into the ligand, the CO₃^2-ion directly with the Ca²⁺ions combine to form a stable crystalline form, resulting in a different crystal formand morphology of mineralization product. This template effect of the theory canexplain the experiments, glycine and serine on the ball aragonite depositioninduced.3、 Three-dimensional network structure of gel-gel method limits the freegrowth of calcium carbonate crystals, calcium carbonate crystal growth into thecalcite crystal form which is stable in thermodynamics and structure; gel methodsystem for different amino acids are generated calcite polymorphs, but themorphology of the calcite crystal form was significantly different, specific reasonsare not clear, pending further experiments.