Surface Tension of Solids in the Absence of Adsorption

Abstract

A method has been recently proposed for determining the value of the surface tension of a solid in the absence of adsorption, γS0, using material properties determined from vapor adsorption experiments. If valid, the value obtained for γS0 must be independent of the vapor used. We apply the proposed method to determine the value of γS0 for four solids using at least two vapors for each solid and find results that support the proposed method for determining γS0.

Adsorption at the solid–liquid interface as the source of contact angle dependence on the curvature of the three-phase line

“…(33) indicates that when x V is near unity, γ SV is reduced to γ LV , the surface tension of the adsorbing fluid. This same behaviour has been seen with other systems as well [12]. 9.…”

“…This gives experimental support to the expression for γ SV , and the wetting hypothesis. We note that this method of examining the predicted values of γ S0 have also been applied to other solids and equally good agreement for the value of γ S0 obtained from the adsorption of different vapours [12].…”

“…The results indicated in Fig. 10 and in reference [12] are the type of results one would expect to obtain if the wetting hypothesis were valid.…”

“…12 this condition is met for two vapours adsorbing on the basal plane of graphite. In reference [12], this test was applied to four solids with γ S0 determined by adsorbing at least two vapours on each solid. In each case γ S0 was found to have the same value, independently of the vapour used to determine its value.…”

“…This provides a method by which the theory may be tested: if two vapours are used to determine the value of γ S0 , and the theory is correct, the same value of γ S0 must be obtained from the isotherm parameters for the two vapours. This condition was found to be satisfied for the adsorption of benzene and for n-hexane adsorbing on the basal plane of graphite [31] and for Ar and N 2 adsorbing at 77 K on alpha-alumina, titania, magnesia and borosilicate glass [12].…”