Preparation Of Anhydrous And Dihvdrate Magnesium Glycine Complexes And Their Thermodvnamic Models

Amino acid metal complexes such as amino acids magnesium(calcium,iron,zinc,and aluminum)are effective metal supplements in the interest of biological,animal,and botanical applications.Among them,magnesium glycine acetate has been widely used in medical and health products,food additives,feed additives,cosmetic additives due to its stable chemical and biological properties,high absorption rate,along with other identified advantages to show great economic values.At present,there are few reports on the industrial preparation of such compounds.Analysis of the limited data provided demonstrated that the synthesis method of amino acid complexes is mainly the synthesis of water systems.Although this method has the advantages of leading to a high yield rate,it is proven to be disadvantageous due to a prolonged reaction cycle,hardness of filtration,and the formation of the unwanted crystal water.In view of this,this paper proposed a novel process for the preparation of dihydrate and anhydrous magnesium glycine using a method managed to control the supersaturation of the solution.The new method not only ameliorates the difficulty of filtration,it also significantly reduced the energy consumption for evaporation,ultimately leads to the formation of magnesium glycine products with ideal morphologies.This research laid a scientific foundation for the production of magnesium glycine products within the broad field of chemical engineering.Altogether,the research reported on the following remarkable results:(1)Magnesium oxide(or magnesium hydroxide)and glycine are used as raw materials,and at 80?,magnesium glycine dihydrate can be prepared by hydrothermal synthesis process.With the increase of the reactant concentration,the crystal form of the magnesium glycine dihydrate product is significantly improved,and the particle size is gradually increased.When a supersaturated glycine solution is used for the reaction,the yield of magnesium glycine dihydrate is significantly improved,and the particle size range is between 10 and 50 ?m.The obtained product is easy to filter which reduces the total energy consumption through evaporation and concentration.(2)Experiments have proved that it is difficult to achieve direct preparation of anhydrous glycine products in organic solutions such as ethanol,but the chemical reagent purchased is magnesium glycine.In this dissertation,the high temperature drying method is used to realize the preparation from dihydrate to anhydrous magnesium glycine.Thermogravimetric analysis unveils that the crystallization dehydration temperature of magnesium glycine dihydrate is about 150?.When the drying temperature exceed this level,the product appearance tends to change from white to yellow.(3)By measuring the magnesium ion concentration of magnesium glycine in an aqueous solution,that is:solubility,and by combining the MSE(Mixed Solvent Electrolytes)model of OLI software enables the accurate calculation of the water activity and the activity coefficient of species included,the solubility product Ksp of magnesium glycine dihydrate is obtained for the first time.The basic thermodynamic properties of the constant Ksp and magnesium glycine dihydrate are:?Hr0?-10.7 kJ·mol-1,?Sr0=-102.831 J·mol-1·K-1,?Gf,298.15K0=19.96 kJ·mol-1.(4)Solubility data of AlCl3·6H2O in NaCl-CaCl2-NH4Cl-H2O system and Li2SO4·H2O in Na2SO4-MgSO4-H2SO4-H2O system were determined by dynamic methods.By tuning the newly-regressed interaction parameters for electrolytes,a new MSE model was constructed.Based on the OLI software platform,the supersaturation of the electrolyte solution can be strictly calculated,which grounds a scientific base for preparing high-quality products through crystallization technology.