RESUMEN
When a nonwetting fluid is forced to infiltrate a hydrophobic nanoporous solid, the external mechanical work is partially dissipated into thermal energy and partially converted to the liquid-solid interface energy to increase its enthalpy, resulting in a system with a superior energy absorption performance. To clarify the energy dissipation and conversion mechanisms, experimental infiltration and defiltration tests of liquid/ion solutions into nanopores of a hydrophobic ZSM-5 zeolite were conducted. The characteristics of energy dissipation were quantified by measuring the temperature variation of the immersed liquid environment and compared against that estimated from pressure-infiltration volume isotherms during infiltration and defiltration stages of the test. Both stages were observed to be endothermic, with the temperature of the liquid phase showing a steady increase with changes in liquid saturation. The confinement of the molecular-sized pore space causes the liquid molecules/ions to transit between statuses of orderly and disorderly motions, resulting in dissipation behaviors that vary with liquid infiltration/defiltration rates and the types and concentrations of additive electrolytes in the liquid-both factors of which alter the characteristics of the nanofluidic transport behavior.
RESUMEN
When measuring interfacial tensions, conventional spinning drop tensiometry requires knowledge of the index of refraction of the denser, outer fluid phase, in order to correct for the magnification of the inner, spinning drop. We have modified a spinning drop tensiometer to accommodate a square section sample tube, which does not require this correction. Tests performed using calibration rods are used to demonstrate this fact. The interfacial tension of toluene and water is also measured using this new design. The ensuing results are in agreement with measurements obtained using a conventional circular sample tube. Copyright 2001 Academic Press.
