抄録
Crystallization has been widely used for product separation and purification in the pharmaceutical, chemical and food industries. To reduce the time and cost in synthesizing crystallization processes, a number of systematic procedures have been established. However, the basis of these procedures requires the acquisition of the solid-liquid equilibrium (SLE) phase diagrams of the chemical systems under consideration, which are often not available in the literature. There is thus a great demand for determining SLE phase diagrams through experimental means. This work aims at presenting a generic scheme that can be carried out to experimentally construct the desired isobaric SLE phase diagram of a given system. Being driven by the process objectives, the scheme helps to generate phase diagrams that contain specific data useful for the development of the targeted process. To demonstrate the implementation of the generic scheme, an experimental apparatus and technique have been developed to measure the isobaric SLE phase diagrams of the ternary system phenol, bisphenol A and water at 1 atm. The technique utilized is based on the solid-disappearance method, in which a point on the saturation boundary is determined by detecting the temperature at which the last trace of solid in the sample mixture disappears. To provide auxiliary information for the phase diagram, crystals are also sampled by suction filtration and analyzed for identities. The resulting SLE phase diagram of the system is found to be in a high degree of accuracy and from which the saturation region of BPA and phenol/BPA adduct can be identified.
