Separations and Material Processing in Solutions with Dense Gases

Abstract

By using thermodynamic phenomena in systems with dense gases, product properties such as morphology, size of particles, and fibers can be tailored to industrial needs. Separation of complex mixtures can be performed. Processes that are conventionally operated in a number of costly steps can be reduced to a few operations. This paper gives a phenomenological classification of such processes and explains the underlying principles. Operations developed on a laboratory scale as well as those already established in industry will be critically discussed and compared to conventional methods. An up-to-date review of the state of development starting from the emergence of these technologies in the early 1980s is given.

Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide

“…[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] The desirable qualities of CO 2 include its low toxicity, tunable solvent properties, and relatively low critical point. Figure 1 shows the temperature dependence of CO 2 density [53] and confirms that CO 2 is highly compressible near its critical point.…”

Fabrication of micro-hollow fiber by electrospinning process in near-critical carbon dioxide

“…The special combination of gas-like viscosity and liquid-like density of a supercritical fluid makes it an excellent solvent for various applications. Supercritical fluids have been used successfully as solvents, antisolvents, or plasticizers in polymer processings; e.g., polymer modification, polymer composites, polymer blending, microcellular foaming, particle production, and in polymer synthesis [9,10,12,13]. Carbon dioxide (CO2) is the most commonly used supercritical fluid because of its low critical temperature (Tc = 304 K) and pressure (Pc = 7.38 MPa), low toxicity and high purity at a low cost.…”

Modeling of Solid/Fluid Phase Equilibria in Multicomponent Systems at High Pressure

“…The latter approach leads to unsatisfying results in the case of a compressible liquid phase, or highpressure processes. This becomes apparent for processes like the suspension polymerization of ethylene in hexane, the crystallization of wax phases during the exploitation of deep, so-called hyperbaric oil reservoirs, as well as for special applications like the Gas-Antisolvent (GAS)-process [3]. In contrast, the calculation of solid/gas equilibria usually requires information about the sublimation pressure of the solid component.…”