|Adsorption on porous carbons
was described as early as 1550 B.C. in an ancient Egyptian papyrus and
later by Hippocrates and Pliny the Elder, mainly for medicinal purposes.
In the 18th century, carbons made from blood, wood and animals were used
for the purification of liquids. All of these materials, which can be
considered as precursors of activated carbons, were only available as
powders. The typical technology of application was the so-called batch
contact treatment, where a measured quantity of carbon and the liquid to
be treated were mixed and, after a certain contact time, separated by
filtration or sedimentation.
At the beginning of the 19th
century the decolourisation power of bone char was detected and used in
the sugar industry in England. Bone char was available as a granular
material which allowed the use of percolation technology, where the
liquid to be treated was continuously passed through a column. Bone
char, however, consists mainly of calcium phosphate and a small
percentage of carbon; this material, therefore was only used for sugar
At the beginning of this
century the first processes were developed to produce activated carbons
with defined properties on an industrial scale. However, the steam
activation (V. Ostreijko, 1900 and 1901) and chemical activation (Bayer,
1915) processes could only produce powder activated carbon.
During the First World War,
steam activation of coconut char was developed in the United States for
use in gas masks. This activated carbon type contains mainly fine
adsorption pore structures suited for gas phase applications.
CALGON CARBON Corporation
(USA), the parent company of CHEMVIRON CARBON succeeded after
World War II, in developing coal based granular activated carbons with a
substantial content of transport pore structure and good
mechanical hardness. This combination allowed the use of activated
carbon in continuous decolourisation processes resulting superior
performance. In addition CALGON CARBON and CHEMVIRON CARBON
pioneered work on the optimization of granular carbon
Today many users are switching
from the traditional use of powdered activated carbon as a disposable
chemical to continuous adsorption processes using granular activated
carbon combined with reactivation. By this change they are following the
modern tendency towards recycling and waste minimization, thereby
reducing the use of the world's resources.