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。这一进展后，吸附等温线制定了光滑的固体表面上的蒸汽吸附时，汽相压力是在零和饱和蒸汽压力之间。该等温线表达式中的参数可以从作为气相压力的函数的吸附量的测量来确定。一旦这些等温线参数是已知的一个特定的汽-固系统，它们可以被用于吉布斯热力学，以获得作为汽相压力的函数的固-汽界面的表面张力的表达式。当汽相压力足够大，可以存在固着液滴时，固液界面的表面张力也可以预测。虽然以前被其他人忽略，我们以前的研究的结论之一是，对于一个给定的温度，一个固着液滴的接触角增加的液相（或气相）的压力增加。这一结论最近得到了强有力的实验支持。基于这些以前的研究，我们正在扩展我们的模型，吸附在多孔材料。该模型表明，在低于饱和蒸气压的压力下，暴露于蒸气的材料中的孔填充的原因是因为孔内的冷凝物的接触角随着蒸气相压力的增加而增加。

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.