The Research And Analysis Of The Migration Of Solute In The Process Of Aqueous Solution Crystallization

Freezing method is the use of cold energy solution for refrigeration, makes the solute or insolubles to migrate on solid-liquid interface, a method to reach the purpose of purifying or enrichment. As a kind of typical chemical unit operation process, freezing crystallization with saving energy consumption, low operation temperature, crystallization degree of corrosion on the equipment is small, improve the operation environment, reduce environmental pollution, etc. Freezing method has been applied to coffee, juice, beer, dairy products and other fields, and in the sea water desalination, sewage treatment, etc, while still at the stage of exploration, but has showed great development potential.This experiment further studied the migration regularity of the solute in the directional freezing in aqueous solution. Experiments using progressive freezing, freezing crystallization was carried out on the aqueous solution containing different solute, then the ice formed on crystallization fixed-point sampling, determine the spatial distribution of the solute. The multi-channel temperature is used in the process of cooling crystallization, in recorder to record each point temperature changes in different time, in order to better study the sequence of crystallization and the temperature change in different area in the quasi static crystallization process. This paper respectively discusses the types of the solute, solution concentration, freezing temperature, solution PH, and the size of the solute migration path to solute migration rate. Experiments use atomic absorption spectrum instrument and ultraviolet spectrophotometer to determine component concentration of the solution after the quasi static crystallization.Results show that the amount of different polarity and different type, different cation of NaCl, MgCl2and CrCl3, KMnO4, glucose as solute respectively, all along the frozen after the quasi static crystallization direction obvious migration happens, the solute density in the center is the largest, while in the edge of the crystal is minimal; the mobility of glucose the worst, namely particle size is larger for solute migration; Alkaline solution of acid for solute migration depends on the influence of H+or OH-interaction with ions in the solution; For the NaCl solution, the smaller the concentration, the bigger the migration path, frozen temperature is more close to the freezing point temperature, the higher the mobility of Na+...