| As an important chemical material and intermediate of organic synthesis, melamine, which molecular formula is C3H6N6, melamine is applied to many industries such as dope, plastic, lumber processing, paper making and weaving, etc.. At present, melamine is synthesized with urea in the world. There are many solid wastes in the process of synthesizing melamine, including some triazines such as melamine, cyanuric acid, ammelide and ammeline, some of which are poisonous and adverse to the environment. With the recognition of the society, separating, reclaiming and recycling solid wastes have gained broad attention.The fundamental research was carried out in this paper aiming at dealing with solid wastes of melamine synthesizing.Solvent dissolving, crystallizing and separating is an effective way to separate mixed solids. Exact and intact solubility data are needed in this method. Reports about solubility of these organic substances are few. In this paper, solubilities of these substances were determined systemically.Groups of melamine, cyanuric acid, ammelide and ammeline were divided with HANSEN method. Group contribution values were got from literatures and the solubility parameters were calculated. Solvents were selected based on principle of 'solubility parameters of solutes and solvents should be equal or near'.The synthetic method monitored by laser and computer on line was installed to determine the solubility of some systems which have quick solid-liquid equilibria. Solubilities of systems of melamine + dimethyl sulfoxide, ammelide + dimethyl sulfoxide, melamine + ethanediol, cyanuric acid + ethanediol, melamine + N,N-dimethyl formamide, cyanuric acid + N,N-dimethyl formamide, melamine + N,N-dimethyl acetamide, cyanuric acid + N,N-dimethyl acetamide, melamine + 1,2-propanediol, melamine + polyethylene glycol400 and melamine + water were determined with this apparatus. As well, another apparatus is set up to determine the solubility of systems which have slow S-L-E. The solubility of cyanuric acid in water was precisely determined with this apparatus using UV spectroscopy analyzing.Sublimation temperature and the heat of sublimation of melamine, decomposition temperature and correlative calorific effect of cyanuric acid, ammelide and ammeline were determined by pressure DSC technique.Solubility data of systems determined were correlated by the two parameter equation and the three parameter equation. The average relative error between the value calculated by those models and the experimental value of those 12 systems were 1.76% and 1.13% respectively.Solubilities of melamine in water, ethanediol, N,N-dimethyl formamide, N,N-dimethyl acetamide, 1,2-propanediol, polyethylene glycol-400, dimethyl sulfoxide, ethanol and propiolic alcohol were correlated by the Wilson equation and the A h equation. The average relative error between the value calculated by those models and the experimental value of those 9 systems were 5.35% and 4.14% respectively.Comparison between those models indicated that correlation using the two parameter equation, the three parameter equation, and the h equation were good, while the error of correlation using the Wilson equation were bigger relatively.As can be seen from the experimental result and the correlative curve that, the solubility of melamine, cyanuric acid, ammelide and ammeline in ethanol are somewhat large and the difference of the solubility of those substances in ethanol are so large that ethanol can be an appropriate solvent to separate the mixed substances. Differnce between solubility of melamine and cyanuric acid in ethanediol, N,N-dimethyl formamide and N,N-dimethyl acetamide are so large that these three solvents can be good solvents to separate melamine and cyanuric acid, while dimethyl sulfoxide can be a good solvent to separate melamine, cyanuric acid and ammelide.The solubility, diagnostic temperature determined and the enthalpy value of solution reckoned in this thesis can give a support to further study of the S-L-E theory and provide a theoretical fo...
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