Detachment of colloids from a solid surface by a moving air–water interface
2008 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 326, no 1, 143-150 p.Article in journal (Refereed) Published
Colloid attachment to liquid–gas interfaces is an important process used in industrial applications toseparate suspended colloids from the fluid phase. Moving gas bubbles can also be used to removecolloidal dust from surfaces. Similarly, moving liquid–gas interfaces lead to colloid mobilization in thenatural subsurface environment, such as in soils and sediments. The objective of this study was toquantify the effect of moving air–water interfaces on the detachment of colloids deposited on an airdriedglass surface, as a function of colloidal properties and interface velocity. We selected four typesof polystyrene colloids (positive and negative surface charge, hydrophilic and hydrophobic). The colloidswere deposited on clean microscope glass slides using a flow-through deposition chamber. Air–waterinterfaces were passed over the colloid-deposited glass slides, and we varied the number of passagesand the interface velocity. The amounts of colloids deposited on the glass slides were visualized usingconfocal laser scanning microscopy and quantified by image analysis. Our results showed that colloidsattached under unfavorable conditions were removed in significantly greater amounts than those attachedunder favorable conditions. Hydrophobic colloids were detached more than hydrophilic colloids. Theeffect of the air–water interface on colloid removal was most pronounced for the first two passagesof the air–water interface. Subsequent passages of air–water interfaces over the colloid-deposited glassslides did not cause significant additional colloid removal. Increasing interface velocity led to decreasedcolloid removal. The force balances, calculated from theory, supported the experimental findings, andhighlight the dominance of detachment forces (surface tension forces) over the attachment forces (DLVOforces).
Place, publisher, year, edition, pages
2008. Vol. 326, no 1, 143-150 p.
Other Environmental Engineering
IdentifiersURN: urn:nbn:se:uu:diva-179768DOI: 10.1016/j.jcis.2008.07.030OAI: oai:DiVA.org:uu-179768DiVA: diva2:546195