Solubility determination and correlation for o-phenylenediamine in (methanol, ethanol, acetonitrile and water) and their binary solvents from T = (283.15-318.15) K

In the present study, the solubility of o-phenylenediamine in four pure solvents (methanol, ethanol, acetonitrile and water) and three binary solvents (methanol + water), (ethanol + water) and (acetonitrile + water) was determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (283.15 to 318.15) K under atmospheric pressure. The solubility increased within creasing temperature in the four pure solvents and binary solvent mixtures at constant solvent composition. At constant temperature and solvent composition, the mole fraction solubility of o-phenylenediamine in four pure solvents decreased according to the following order: acetonitrile > methanol > ethanol > water; and in the three binary solvent mixtures ranked as (acetonitrile + water) > (methanol + water) > (ethanol + water). The dependence of o-phenylenediamine solubility in mole fraction on temperature and solvent composition in the binary solvent mixtures was correlated by employing the Jouyban-Acree model, van't Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model, Ma model and Sun model. The largest value of relative average deviations (RAD) was 4.79 x 10(-2); and of root-mean-square deviations (RMSD), 4.14 x 10(-3). The five models were proven to give good representation of the experimental solubility results. Furthermore, the apparent enthalpy of the dissolution process was calculated. The dissolution process of o-phenylenediamine in the mixed solvents was endothermic. The experimental solubility and the models in this study could be helpful in purifying o-phenylenediamine. (C) 2016 Elsevier Ltd.