Research On Solid-liquid Equilibrium Of Two Organic Acids And One Ketone

Phase equilibrium is an important part of chemical thermodynamics research,any process development and optimization based on thermal separation cannot do without the original data of phase equilibrium.The solubility of solute in solvent is preliminarily studied by solid-liquid equilibrium.The study of solid-liquid equilibrium is the premise of crystallization process optimization,which not only provides necessary phase equilibrium data,but also provides key basic elements for crystallizer design.This paper studies the solid-liquid equilibrium of three kinds of organic compounds,including 4-Biphenylcarboxylic acid,2-Benzoylbenzoic acid and 2-Hydroxy-4-methoxybenzophenone.The specific research contents are summarized as follows:(1)The solubility data of 4-Biphenylcarboxylic acid,2-Benzoylbenzoic acid and 2-Hydroxy-4-methoxybenzophenone,in common organic solvents were determined by gravimetric analysis under atmospheric pressure and within a certain temperature range.This work explored the influence of temperature,solvent type,composition and other factors on the dissolution process,then the co-dissolution effect in mixed solvents was analyzed.(2)Thermodynamic analysis was performed on the dissolution data of three kinds of organic compounds,including 4-Biphenylcarboxylic acid,2-Benzoylbenzoic acid and 2-Hydroxy-4-methoxybenzophenone in pure solvents by Wilson model.By studying the mixing entropy,mixing enthalpy and mixing Gibbs free energy,we found that the mixing process of three substances in each solvent is a spontaneous process.(3)Various solid-liquid equilibrium models,including empirical equations(Apelblat equation,Van’t Hoff equation,λh equation),activity coefficient equations(Wilson equation,NRTL equation)and mixed solvent models(CNIBS/RK,Jouyban-Acree,Apelblat-Jouyban-Acree,Van’t Hoff-Jouyban-Acree,Sun,Ma)were used to analyze the solubility data in different systems to obtain the parameter of each model.The experimental data were compared with the theoretical results,and the relative average deviation was calculated.Finally,we found that the fitting results of each model were good.(4)This work defined a new group and calculated the volume parameter and surface area parameter of the group.Based on the UNIQUAC model,the relative average deviations of three substances were all less than3%,which indicated that the defined new group was available.In summary,the solubility,thermodynamic parameters and model parameters of three organic compounds,including 4-Biphenylcarboxylic acid,2-Benzoylbenzoic acid and 2-Hydroxy-4-methoxybenzophenone,were measured in this work,which fills the blank of solid-liquid equilibrium data of the three materials and provides indispensable theoretical guidance for subsequent crystallization technology.