Correlation of solubility and calculation of thermodynamic properties of guanidine nitrate in different solvents

• Solubility of GN in five different solvents was determined using gravimetric method.
• Dissolution enthalpy and entropy of GN in five different solvents were estimated.
• Activity coefficient in different solvents was calculated.

To realize the rapid solvent screening and further crystallization process optimization, experimental determination of accurate solubility data of target solute in potential solvents is necessary. Using a gravimetric method, solubilities of guanidine nitrate in water, methanol, ethanol, n-propanol and acetone at temperature ranging from 278.05 K to 332.85 K at pressure p = 0.1 MPa were experimentally measured. Melting temperature, Tm, and fusion enthalpy, ΔHf, of guanidine nitrate were determined using differential scanning calorimetry. Subsequently, Apelblat equation, van’t Hoff equation, λh equation, and Wilson model were used to correlate the measured solubility data, respectively. Dissolution of guanidine nitrate in all examined solvents was found to be endothermic and entropically favorable. Moreover, the measured solubility data were combined with calculated ideal solubility data to calculate activity coefficients at infinite dilution based on the assumption of ΔCp = 0, which were then fitted to a van’t Hoff like regular solution equation.