Wetting, Adsorption, and Cleaning Processes - Surface and Colloid Chemistry: Principles and Applications - page 131

6 Wetting, Adsorption,

and Cleaning Processes

6.1 IntroductIon
When a liquid comes into contact with a solid, there are a few processes of interest
to analyze. These are

Wetting
Adsorption
Cleaning

One finds that the wetting characteristics of any solid surface play an important role
in all kinds of systems. The next most important step is the process of adsorption
of substances on solid surfaces. These phenomena are the crucial steps for all kinds
of cleaning processes. Typical systems involved are washing, coatings, adhesion,
lubrication, oil recovery, etc.
The liquid-solid or liquid 1 -solid-liquid 2 system is both a contact angle (Young's
equation) and capillary phenomena (Laplace equation). These two parameters are

Cos (θ) = (γ S - γ SL )/γ L (5.4)

and

ΔP = (2 γ L Cos [θ])/radius (6.1)

In the following, we will consider some significant phenomena where these param-
eters are of importance.

6.2 oIl recovery and SurFace ForceS
Oil is normally found under high temperatures (80°C) and pressures (200 atm). Oil in
reservoirs is produced under high-pressure conditions. The pressure needed depends
primarily on the porosity of the reservoir rock and the viscosity of the oil, among
other factors. This creates flow of oil through the rocks, which consists of pores of
varying sizes and shapes. Roughly, one may compare oil flow to the squeezing of
water out of a sponge.

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