Non-Linear Coefficients for Electroosmotic Transport of Alcohols through Porous Diaphragms

Abstract

An experimental investigation of electroosmosis for the nonlinear region is described. Porous diaphragms of pyrex glass particles, whose diameters were in the range 150-500 μιη, and methyl-, ethyl-, and iso-propyl alcohols have been used to perform the electroosmotic experiments. The phenomenological coefficient L m was found to be non-significant at the 95% confidence level. The electroosmotic flux dependence on ΔΦ for the pyrex-ethanol system in the non-linear range is opposed to that of the pyrex-methanol system. The contribution of the L 112 coefficient had a significant value only when ethyl-alcohol was employed as a permeant. Its sign changes from positive to negative when the thickness of the porous diaphragm is lowered below 1.50 cm. For pyrex-ethanol systems, the L 122 phenomenological coefficient was found to be independent on the thickness of the plug and its absolute value to increase when the size of the particles of the plug was decreased. For pyrex-methanol systems, there seems to be no dependence of the above coefficient on the size of the particles forming the plug. Furthermore, L 122 increases its value when the thickness of the plug is diminished. When iso-propyl alcohol was employed as a permeant, linearity was observed up to ΔΦ equal to 900 V.

Concentration Dependence of Transport Coefficients of Binary and Ternary Mixtures Through Inactive Membranes

“…The apparatus used and its experimental setup have been described earlier [13][14][15][16]. Pyrex glass, S-732-01 from Sovirel (France) was crushed and sieved to obtain the fraction between 150-200 μτη.…”

The effect of tannic acid on the electrical properties of the interface and the non-linear streaming potential of cellulose in a cationic dye solution

“…In the same way as with coefficient L,,,, it is possible to give an interpretation of coefficient L,,, on the basis of a generalized coefficient Lf2, defined as16 whose physical significance is that of a 'generalized electrical conductance'. In using such a coefficient, L,,, is given by L,,, = (*) aAP (9) where the zero subscript means that the derivative is evaluated at the thermodynamic equilibrium. Thus, L,,, gives the extent of the changes of the generalized electrical conductance of the system as a consequence of the applied pressure gradient, which gives rise to alterations in the hydrodynamic flow into the capillaries.…”

On the Use of Generalized Onsager Coefficients in Nonlinear Electroosmotic Phenomena

“…The experimental setup and procedure followed for hydrodynamic permeability and electroosmotic permeability measurements were the same as described earlier [6,12]. For the determination of the electroosmotic flux, the desired potential difference was applied across the plug with an electrically operated power suply, Kepco OPS 1000.…”

“…In the last years, non-linear effects in electrokinetic phenomena have been studied more systematically, in order to gain a wider knowledge on the interfacial properties in different systems [1][2][3][4][5][6][7]. When discussed in the light of Thermodynamics of Irreversible Processes, the electrokinetic phenomena are described by phenomenological equations, relating thermodynamic forces and fluxes.…”