INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
capítulos de libros
Título:
Adsorption of particles onto metallic surfaces
Autor/es:
E M ANDRADE; F. V. MOLINA
Libro:
Encyclopedia of Surface and Colloid Science
Editorial:
Taylor and Francis
Referencias:
Lugar: New York; Año: 2006; p. 555 - 574
Resumen:
Particles
are present all around us in great abundance. They include, for example,
pollens, dusts, fibers, metals, metal oxides, bacteria, etc. The adsorption or
(as it is more usually termed) adhesion of colloidal particles onto metallic
surfaces is a field relevant to many applied problems. The term colloidal
particle refers to a broad range of sizes, from macromolecules and small
crystalline nuclei of about 1 nm to macroscopical particles of the order of 10 mm (139)(54). As a result, there are a variety of
effects and particular properties of the particles/surface system. The
particles can become adhered to a metallic surface by several forces, such as
electrostatic, dispersion, capillary and chemical bonding (140)(93)(61). In a
general sense, a surface with colloidal particles adhered is modified by these
particles, and the effect of such modification, depending on the particular
system and its applications, may be advantageous, such as the case of powder
coatings, or nonadvantageous, as when adhesion of particles cause fouling of
materials and equipment parts. Particles adhere to surfaces with great
tenacity. If a surface with adhered particles is inverted it is observed that
they do not detach, even for particles that are quite large, showing that the
adhesion force is greater than the gravitational force on those particles.
Similarly, vigorous blowing of the surface only manages to dislodge relatively
few particles.
Despite
its importance, the adhesion of particles to metallic surfaces has not received
too much attention in fundamental studies; there are far more papers published
either on adherence of particles to non conducting surfaces or to different
particles (heterocoagulation). In the former case the surface electric
potential cannot be easily modified, whereas in the latter the surface
potentials cannot usually be modified independently, because the potential
determining ion (pdi) is the hydrogen ion for both surfaces. Those topics are
covered elsewhere in this Encyclopedia (see the entries "Adsorption of
Immunoglobulins at Solid-Liquid Interfaces", "Adsorption of
Polyelectrolytes on Mica", "Particles at Polymer Surfaces",
"Adsorption of Polyethoxyethylenic Surfactants on Clay Surfaces", "Surface
Behavior of Bacteria" and "Adsorption of Particles: Theory"). In
the following sections we will review some application fields, the theoretical
work on adhesion and its applications to metal/particle systems, experimental
methods to study these systems, recent experimental research, and finally we
will draw some conclusions. We will consider mainly particle/metal adhesion in
liquid media, although references to gas phase will be also made.