How does adsorption work?
Adsorption (with a d) is caused by intermolecular Van der Waals Forces allowing molecules to stick to a solid surface.  The solid surface can be described using a Langmiur model.  In this model a surface can bind with a number of gas molecules at any number of active sites. These active sites may be packed much closer together than molecules dispersed in a gaseous state. When dispersed gaseous molecules in a closed container interact with a surface packed with active sites, the surface may appear to "suck the gas molecules" as the gas molecules bind to the densely packed active sites.  

This suction is particularly true of several activated carbons because the porous surface causes a large number of active sites to pack together.  

The Langmuir model is only one model. In this model once all of the active sites are filled, the gas around the surface forms a monolayer. The monolayer is expanded upon in more sophisticated models such as the BET model.  The BET model is used to analytically determine BET surface area of a material like activated carbon.  

Sometimes the behavior of the surface is described empirically such as in the Freundlich adsorption isotherm.  In this case, as with all empirical models, there is no explanation for the attraction sucking molecules to the surface.  It is simply accepted the model works.