A systematic scheme for the experimental determination of isobaric solid-liquid equilibrium (SLE) phase diagrams at atmospheric pressure is presented. Driven by process objectives and aided by techniques for representing/visualizing phase diagrams, the scheme helps to generate such diagrams exhibiting features (for example, feasible crystallization product region) that are useful for the synthesis and design of crystallization-based process flowsheets. To illustrate the execution of this scheme, the isobaric SLE phase diagrams of two organic systems were measured. These include a system containing phenol, bisphenol A, and water and a polymorphic system consisting of sulfamerazine and dimethyl sulfoxide.

in Wiley InterScience (www.interscience.wiley.com).A coherent, systematic approach for the determination of solid-liquid phase behavior of a multi-component salt lake system for use in the synthesis of crystallization process is presented. It centers on the thermodynamics of such a salt lake system and integrates three interrelated activities-representation of the system phase behavior as a phase diagram/thermodynamic model, experimental determination of the necessary data and visualization of the relevant crystallization regions. To illustrate this approach, the thermodynamics of a simplified salt lake system Li 1 , Na 1 , K 1 , Mg 21 // Cl 2 , SO 4 22 -H 2 O at 258C and 1 atm was determined. The identification of process alternatives using the resulting phase diagram for recovering Li 2 SO 4 ÁH 2 O was also illustrated.

A crystallization-based process that separates pure fullerenes C 60 and C 70 from their mixture using o-xylene as the solvent has been developed. Isothermal solid-liquid equilibrium phase diagrams of the C 60 -C 70 -o-xylene ternary system for a number of temperatures were first determined at 1 atm. Taking advantage of the shift in solvent-free composition of the C 60 -C 70 double saturation point with temperature and based on the solid solution-forming phase behavior between C 60 and C 70 , the flowsheet of a general crystallization process was then synthesized. It involved the fractionation of a C 60 -C 70 fullerene mixture into C 60 -rich and C 70 -rich solid solutions using temperature-swing crystallization, followed by purification of the solid solutions with multistage crystallization into pure C 60 and C 70 solids. To demonstrate process feasibility, bench-scale batch experiments were performed using a commercially available fullerene mixture that was pretreated by adsorption to remove higher fullerenes. C 60 and C 70 solids of purity higher than 99 wt % were obtained.