Hydroquinone solubility and separation processes

Abstract

In chemical process design, separation unitsare usually veryimportant for the purification of one or more components from thereaction stage. This step may involve different fluid or solid phases.Chemical engineering thermodynamics is the area of chemicalengineering that studies the distribution of such components amongequilibrium phases given temperature, pressure and feed composition.Therefore, reliable and accurate data on phase equilibria are crucial tooptimize and scale up process separation units. As the number of realconditions in which the interest may be focused in is extremely high,thermodynamic models are frequently used to provide estimates of suchdata. Among these models,those based on the excess Gibbs energy,regularly known as activity coefficient models, and equations of statearethe most widely used. In this work, an overview of some thermodynamic models to describe the phase equilibria of hydroquinone and its isomers isprovided, with the focus on the conditions commonly used for itsseparation processes. Results on the solid-liquid equilibria in water andorganic solvents as a function of temperature, as well as in supercriticalcarbon dioxide as a function of pressure at several temperatures will bepresented using the Non-Random Two Liquid Segment ActivityCoefficient model (NRTL-SAC), the UNIFAC, the A-UNIFAC and theCubic-plus-Association equation of state (CPA).