Study On Solid-Liquid Equilibria Solubility Of Azobisisobutyronitrile And Benzoyl Peroxide

The solid-liquid equilibria solubility of azobisisobutyronitrile and benzoyl peroxide in methanol and dimethyl carbonate solvents and mixtures were determined by the laser diffraction experimental apparatus of a full closed box, which was independent designed and installed, and the solubility and thermodynamic properties of azobisisobutyronitrile and benzoyl peroxide in methanol and dimethyl carbonate solvents and mixtures were correlated by thermodynamics models, which offered basic thermodynamics data for application in emulsion polymerization, crystalization and separation for azobisisobutyronitrile and benzoyl peroxide. The study was introduced as follows.Firstly, used the laser diffraction assistance dynamic method to determine the solubility of potassium chloride in water at 283.35K to 357.05K and the solubility of benzoic acid in water at 289.15K to 363.25K. The experimental data were in good agreement with the manual data, which indicated that the experimental equipment and method were accurate and reliable.Secondly, the solubility of azobisisobutyronitrile and benzoyl peroxide in methanol, dimethyl carbonate and methanol+dimethyl carbonate mixtures with 0.2、0.3、0.4、0.5、0.6、0.7、0.8 mass fraction of methanol were measured by the laser diffraction assistance dynamic method in the temperature range from 284.75K to 344.95K, respectively. The results showed that the solubility of azobisisobutyronitrile and benzoyl peroxide in the selected solvents increased with increasing of temperature, and the solubility of the two kinds of initiators in methanol and in the mixtures with high content were low. Methanol is a polar solvent, whereas dimethyl carbonate is a nonpolar solvent. According to similarity-intermiscibility theory, azobisisobutyronitrile and benzoyl peroxide were nonpolar solutes.Thirdly, linear fitting by Van’t Hoff equation, the dissolution process was analyzed, obtaining five thermodynamic parameters, namely, dissolution enthalpy, dissolution entropy, Gibbs energy change, ζH and ζTs The results showed that dissolution enthalpy and dissolution entropy are all positive values, which indicated that the dissolution process of azobisisobutyronitrile and benzoyl peroxide wre endothermic and irreversible. The values of ζH and ζTS of azobisisobutyronitrile and benzoyl peroxide are 54% and 46%,56% and 44%, respectively, which indicated that enthalpy change and entropy change both control the dissolution process. The effect of enthalpy change on the Gibbs energy change is slightly higher than that of entropy change.Fourthly, solubility data of azobisisobutyronitrile and benzoyl peroxide in pure solvents and mixtures was correlated by solubility models which were Wilson、NRTL、UNIQUAC、Apelblat、polynomial equations. The results showed that the associated models for solubility of azobisisobutyronitrile and benzoyl peroxide in methanol and dimethyl carbonate pure solvents were Apelblat equations. The total relative average deviations of the model were 0.49% and 0.29%, respectively. The associated models for solubility of azobisisobutyronitrile in methanol+dimethyl carbonate mixtures were NRTL and Apelblat equations. The total relative average deviations of the models were 0.46% and 0.59%, respectively. The associated models for solubility of benzoyl peroxide in methanol+dimethyl carbonate mixtures were UNIQUAC and Apelblat equations. The total relative average deviations of the models were 0.30% and 0.57%, respectively.