In this paper, the supercritical-fluid extraction (SCFE) of a packed bed of β-naphthol-impregnated
porous pellets was studied. An increasing number of industrial SCFE processes involve the
extraction of a solute retained within a porous matrix, usually in the form of seeds or irregular
grains. The interest in high-pressure extraction is due to certain advantages of dense gases and
near-critical solvents over conventional liquid solvents. In this study, modified carbon dioxide
was the fluid studied. The effects of temperature, pressure, fluid velocity, particle size, and gravity
were experimentally studied using carbon dioxide, pure or mixed with varying amounts of toluene
(6%, and 10%). For the solute, β-naphthol, the solubilities in SC carbon dioxide mixtures (from
0 to 10% toluene) were available from separate experiments. The dispersed plug-flow model
was used to describe the nonideal flow. Fitting the experimental data with the model solution
allowed the measurements of the fluid-to-particle mass transfer coefficient, the intraparticle
diffusivity, and the axial dispersion coefficient (the latter in terms of the axial Peclet number).
The influence of cosolvent concentration on the three transport parameters, which were not
available so far, is presented.
In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the (E, T ) phase diagram of the studied product can be obtained. In this work, we make a slight modification to the measurement principles based on this method. This modification allows the characteristic parameters of ferroelectric liquid crystal to be quantitatively measured. The use of a current square signal highlights a phenomenon of ferroelectric hysteresis with remnant polarization at null field, which points out an effect of memory in this compound.
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