Preparation Of Bundle Nesquehonite Crystal And Research On Hydration Kinetics Of Multiple Morphologies Crystal

The regulation and synthesis of micro nano particles is an important part of the development of micro nano technology and the basis of the exploration of the micro nano structure properties and its applications.As a member of the family of magnesium carbonate,the crystal of the nesquehonite is a micron grade single crystal synthesized by low temperature liquid phase method,and it has high performance-cost ratio and draws much attention in the new material field.Due to the high purity and low thermal decomposition temperature,it can be used as a precursor to the synthesis of high purity magnesium salt.Because of the low production cost,mild preparation conditions and wide application,it is determined that the nesquehonite crystal has great potential application value and will become a fine magnesium salt chemical products with great development potential.But in the research of the synthesis of nesquehonite crystal,variety of the micro morphology has been confirmed by many researchers.At present,the research focuses on the preparation of different structure crystals,the crystal morphology has been synthesized.The crystal morphology of the crystals is only rod anc radial,and the other is still a great challenge,which is a weak point for the study of crystal growth kinetics.In the thesis,nesquehonite crystal was synthesized in low temperature liquid phase method,and the best experimental conditions were found through single factor experiments,namely:to regulate the temperature of 40? degree,initial concentration of the reactant 0.15 mol/L,set stirring speed 120r/min,stirring reaction time for 60min,regulating pH value of the reaction solution to 9.5,choose CTAB as surfactant.The optimum adding amount(?)95%.Based on this,the Avrami model,Nielsen's evolution model,autocatalytic reaction model derivation were used to fit and analysis the growth process of fascicular,radial,rod nesquehonite in this paper,ultimately hydration kinetics of different morphologies nesquehonite crystal were determined,namely:the bundle nesquehonite crystal dynamics model:x=1/(1+e-0.0653t(1.2-C)+0.188),(0?t?60);the radial nesquehonite crystal dynamics model:X=1/(1+e-0.036281(1 6-C)-0.32615),(0?t?60);the rod nesquehonite crystal dynamics model,according to different time of the reaction crystallization,is divided into two stages:when the reaction time is in 0-15min,dynamic model for X=(4.1814-C)/[1/(-0.00125t+0.3408)+C],when the reaction time is in 15-60min,kinetic model for X=1-exp[-exp(0.0385)t0.2358].The study on morphology control and hydration kinetics of nesquehonite crystals not only enriches controllable preparation of magnesium carbonate in the theory and method to lay scientific foundation for commercial process to product high-performance nesquehonite for fine magnesium salt chemical products at low cost,but also provides a new research method for the development of inorganic micro nano material,and provides a theoretical basis for further exploration of the scientific regulation of micro nano crystal morphology.