Hydrocarbon Vapour Adsorption on Porous Materials

已经取得了一项进展，可以测定暴露于蒸汽或液体中的固体的表面张力。当气相压介于零和饱和蒸汽压之间时，在光滑固体表面上的蒸汽吸附制定了吸附等温线，这一进展就出现了。这个等温线表达式中的参数可以通过测量吸附量作为气相压的函数来确定。一旦这些等温线参数已知了一个特定的气固系统，它们就可以用在吉布斯热力学中，以获得作为气相压力函数的固-气界面表面张力的表达式。当气相压力足够大时，固液界面的表面张力也可以预测。虽然以前被别人忽视，但我们以前的研究结论之一是，在给定的温度下，固相液滴的接触角随着液相（或气相）压力的增加而增加。这一结论最近得到了强有力的实验支持。基于这些先前的研究，我们将我们的模型扩展到多孔材料上的吸附。该模型表明，在低于饱和蒸汽压的压力下，暴露于蒸汽中的材料孔隙充满的原因是，随着气相压力的增加，孔隙内冷凝物的接触角增加。

An advance has been made that allows the surface tensions of solids that are exposed to either a vapour or a liquid to be determined. This advance came after an adsorption isotherm was formulated for vapour adsorption on smooth solid surfaces when the vapour-phase pressure is between zero and the saturation-vapour pressure. The parameters in this isotherm expression can be determined from measurements of the amount adsorbed as a function of the vapour-phase pressure. Once these isotherm parameters are known for a particular vapour-solid system, they may be used in Gibbsian thermodynamics to obtain the expression for the surface tension of the solid-vapour interface as a function of the vapour-phase pressure. When the vapour-phase pressure is large enough so a sessile droplet can exist, the surface tension of the solid-liquid interface can also be predicted. Although neglected previously by others, one of the conclusions of our previous studies is that for a given temperature, the contact angle of a sessile droplet increases as the liquid-phase (or the vapour-phase) pressure increases. This conclusion has recently received strong experimental support. Based on these previous studies, we are extending our model to adsorption on porous materials. This model indicates that the reason the pores in a material exposed to a vapour fill at pressures below the saturation-vapour pressure is because the contact angle of the condensate within a pore increases as the vapour-phase pressure is increased.