On colloidal particle sorption onto a stagnant air–water interface

This paper reviews reported experimental investigations of colloidal particle sorption onto a stagnant air–water interface and presents the results of some new work performed by the authors. A general consensus has emerged, based on the reported data, that particle sorption onto the interface is irreversible. Such irreversibility has been attributed to a capillary trapping caused by a net negative change in the interfacial energies, associated with transferring a fully immersed particle to the interface. The colloidal particle sorption onto an air–water interface depends on the energy barriers between sorbing particles and the interface and between particles in the bulk solution. The heights of these energy barriers, and the separation distances at which they occur, have been determined, based on the DLVO theory, after incorporating the effects of the solvation zone around particles and of the air–water interfacial region in calculating the van der Waals interaction energies.