Chemistry Reference
In-Depth Information
1
Introduction to
Surfaces and Colloids
1.1 IntroductIon
In everyday life, reactions and changes are observed that are dependent on the struc-
tures of the involved matter (which may be
solids, liquids,
or
gases
). However, in
many industrial (chemical industry and technology) and natural biological phenom-
ena, it is found that some processes require a more detailed definition of matter.
Matter exists as
Gas
Liquid
Solid
phases, as has been recognized by classical science (as depicted in the following text).
1.2 SolId PhaSe-lIquId PhaSe-GaS PhaSe
The molecules that are situated at the
interfaces
(e.g., between gas-liquid, gas-solid,
liquid-solid, liquid
1
-liquid
2
, and solid
1
-solid
2
) are known to behave differently from
those in the bulk phase (Adam, 1930; Aveyard and Hayden, 1973; Bakker, 1926;
Bancroft, 1932; Partington, 1951; Davies and Rideal, 1963; Defay et al., 1966; Gaines,
1966; Harkins, 1952; Holmberg, 2004; Matijevic, 1969; Fendler and Fendler, 1975;
Adamson and Gast, 1997; Chattoraj and Birdi, 1984; Birdi, 1989, 1997, 1999, 2002,
2009; Miller and Neogi, 2008; Somasundaran, 2006). Typical examples are
•
Liquid surfaces
•
Surfaces of oceans (liquid-air interface)
•
Solid surfaces (adhesion, glues, tapes)
•
Road surface (solid-air or solid-car tire)
•
Lung surface
•
Washing and cleaning (surfaces, foams)
•
Emulsions (cosmetics, pharmaceutical products)
•
Diverse industries (oil and gas, paper, milk products)
In this chapter, a very short general description of surfaces and colloids (small par-
ticles) is given. For instance, reactions taking place at the surface of the oceans will be
expected to be different from those observed deep inside the water. Further, in some
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