Measurement and Correlation of Solubility of Dicyandiamide in Five Binary Solvents from 283.15 to 323.15 K

The solid–liquid equilibrium solubility of dicyandiamide (DCD) in five kinds of binary solvent mixtures (water + ethanol, water + n-propanol, water + N,N-dimethylformamide (DMF), water + acetonitrile, and DMF + ethyl acetate) at T = (283.15–323.15) K was determined by gravimetric method. The solubility of DCD in the five groups of binary mixed solvents increases with the increase of temperature. In the mixed solvent of water + DMF, the solubility of DCD decreases monotonically with the increase in water content. And in the mixed solvent of DMF + ethyl acetate, the solubility of DCD monotonically increases with the increase of DMF content. Among the other three mixed solvents, with the increase of the water component, the solubility of DCD first increases and then decreases after reaching the peak. The maximum solubility value in water + ethanol, water + n-propanol, and water + acetonitrile is reflected when the water ratio is 0.6. The modified Apelblat model, van’t Hoff model, λh model, Apelblat–Jouyban–Acree model, and the nonrandom two-liquid model were used to correlate the solubility data. The results show that the modified Apelblat model has the best correlation with the solubility of DCD.