Hydrocarbon Vapour Adsorption on Porous Materials

已经取得了一项进展，可以测定暴露在蒸气或液体中的固体的表面张力。这一进展是在建立了当汽相压力在零和饱和蒸汽压力之间时，蒸汽在光滑固体表面上吸附的吸附等温线之后。该等温线表达式中的参数可以通过测量作为汽相压力的函数的吸附量来确定。一旦这些等温线参数对于特定的汽固体系是已知的，它们就可以用于吉布斯热力学，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，也可以预测固-液界面的表面张力。虽然以前的研究被忽略了，但我们以前的研究的一个结论是，对于给定的温度，固着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。在前人研究的基础上，我们将把我们的模型推广到多孔材料上。这一模型表明，材料中的孔隙暴露在低于饱和蒸气压力的蒸汽填充压力下的原因是因为孔隙内凝析油的接触角随着汽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.