Predicting the wettability of quartz surfaces exposed to dense nonaqueous phase liquids.
A model incorporating electrostatic and van der Waals forces was used to predict the wetting behavior of several systems containing a quartz surface, water, and a dense nonaqueous phase liquid (DNAPL). The disjoining pressure between the quartz/water and a water/DNAPL interface as a function of their separation was calculated from a full solution of the nonlinear Poisson-Boltzmann equation allowing for charge regulation. For the pH regime associated with a positive pressure barrier, the quartz surface was predicted to be water wetting. The model takes into account the charging behavior of an isolated DNAPL/water interface as inferred from electrophoretic mobility data. It provides excellent predictions for four coal tar and creosote samples tested, where the quartz was oil-wetting below pH 5 and water-wetting at higher pH values. In a fifth sample, the transition occurred above pH 7, which indicates that mechanisms other than electrostatic interaction control the wetting behavior in this sample.
Zheng
J
J
Department of Civil and Environmental Engineering, Clarkson University, Potsdam, New York 13699-5710, USA.
Behrens
S H
SH
Borkovec
M
M
Powers
S E
SE
D004787:Environmental Pollution / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D011312:Pressure; D011791:Quartz / Q000737:chemistry*; D055672:Static Electricity; D014867:Water / Q000737:chemistry
D014867:Water; D011791:Quartz