Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The salt mixture is crystallized and buried underground, as hazardous waste, not only harmful to the environment, but also caused low pollution use resources. Thus, to research the gradual separation processes of pure salts crystallized from high salinity brine of MTO in coal-chemical industry is momentous. The thermodynamic equilibrium of Na+//Cl-, SO4 2-, NO3 -, CO3 2- -H2O quinary system is essential to realize zero emissions for high salinity wastewater of MTO. Development of coal chemical industry in high salinity wastewater treatment technology, the production of sodium sulfate, sodium chloride, nitrate sodium, sodium carbonate (refined industrial salt) and water recycling technology. The phase diagram of salt-water system plays a role in predicting and guiding the purification process, especially crystallization process. The phase equilibrium and physic-chemical properties of NaNO3 + NaCl + H2O and NaNO3 + Na2CO3 + H2O systems at the temperature of 313.15 K were obtained by the method of isothermal solution saturation. The results showed that one invariant point, two univariant curves, three crystallization fields are existed in both of systems. Each invariant point in the phase diagrams were analyzed. The physical properties (c, n, pH, nD) of the systems change regularly with composition changing of liquid solution. The quaternary phase equilibrium in Na+ //C1-, CO3 2-, NO3 - -H2O system at 313.15K was also researched by means the through and intermediate translation techniques together. Thus, the research results, especially the crystalline regions, would be of great value in designing and optimizing the crystallization process of NaCl and other salts in high salinity brine treated with MTO.