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38 2. Adsorption, Ion Exchange, and Catalysis

The term “adsorption” was first used by H. Kayser in 1881. J. . McBain introduced a W
similar term in 1909, i.e. “absorption”, to determine an uptake of hydrogen by carbon
much slower than adsorption. He proposed the term “sorption” for adsorption and absorp-
tion (Dabrowski, 2001).
In 1903, Tswett was the first to study selectie adsorption. He inestigated the separa- v v
tion of chlorophyll and other plant pigments using silica materials. This technique pro-
posed by Tswett has been called “column solid–liquid adsorption chromatography ” .
However, there w as no sound theory that enabled the interpretation of adsorption isotherm
data untill 1914. Despite the fact that the Freundlich equation was used, there was no theo-
retical justification for it. It was an empirical equation, proposed actually by v an
er
,
we
v
Bemmelen in 1888. Ho it is today known as the Freundlich equation because
Freundlich assigned great importance to it and popularized its use. Langmuir was the f irst
v
to hae introduced a clear concept of the monomolecular adsorption on ener getically
v
homogeneous surfaces in 1918 and deried the homonymous equation based on kinetic
studies (Dabrowski, 2001).
The first practical applications of adsorption were based on the selectie remoal of v v
individual components from their mixtures using other substances. The first filters for
water treatment were installed in Europe and the United States in 1929 and 1930, respec-
tively. Actias recognized as an efficient purification and separation material ated carbon w v
for the synthetic chemical industry in the 1940s. By the late 1960s and early 1970s, acti-
vated carbon was used in many applications for removing a broad spectrum of synthetic
chemicals from water and gases.
In Table 2.3, the history of adsorption is presented briefly .

2.2.2 Ion exchange

The first citation of an application of ion exchange can be found in Aristotle’ s
Problematica , where it is mentioned that sand filters were used for the purification of sea
aters.
and impure drinking wThat is also the first environmental application. In the same
book, Aristotle suggested that desalination resulted from density effects. It seems that
practical applications of ion exchange were well recognized before the 19th century .
However, the underlying physical phenomenon was not known. Credit for the identif ica-
tion of the ion-exchange phenomenon is attributed to two agriculture chemists, Thomson
and Way. In 1848, Thomson reported to ay that he had found that urine w as decolorized W
and deodorized during the filtration of liquid manure through a bed of an ordinary loamy
as who illustrated the basic characteristics of ion e soil. It wWay, xchange after conducting
several experiments (Lucy, 2003).
After soil and clays, natural and synthetic aluminum silicates and synthetic zeolites
er
we
,
were tested as ion-exchange materials by other scientists. Ho the first practical
v
applications of ion exchange took place in the early 20th century .
The first synthetic organic resins were synthesized in 1935. This spectacular e v olution
began with the finding of two English chemists, Adams and Holmes, who found that
crushed phonograph records exhibited ion-exchange properties (Helf 1962). Much ferich,
xchange,
orld
progress was made during WWar II in the field of ion e but the results