Page 6 - Adsorption Technology & Design, Elsevier (1998)

The development of adsorption technology 3

1.2 EARLY COMMERCIAL PRACTICE

Full details of early commercial practice can be found in the writings of
Mantell (1951). The oil industry used naturally occurring clays to refine oils
and fats as long ago as the birth of that industry in the early part of the
twentieth century. Clay minerals for removing grease from woollen
materials (known as the practice of fulling) were used extensively. The min-
eral came to be known as fuller's earth. Its composition consists chiefly of
silica with lower amounts of alumina, ferric oxide and potassium (analysed
as the oxide). Other naturally occurring clays (kaolin and bentonite) also
contain large proportions of silica with smaller proportions of alumina and
were also used for bleaching oils and petroleum spirits. Two methods were
in common use for decolouring oil and petroleum products: the oil could be
percolated through a bed of granular clay or it could be directly contacted
and agitated with the clay mineral. The oil or lubricant to be bleached was
first treated with sulphuric acid and a little clay, filtered and subsequently
run into mixing agitators containing the adsorbent clay and which decolour-
ized the lubricant after a sufficiently long contact time (of the order of one to
three minutes) and at a suitable temperature (usually about 60-65~
Another mineral, which was widely used as a drying agent, was refined
bauxite which consists of hydrated aluminium oxide. It was also used for
decolourizing residual oil stocks. Another form of aluminium oxide mineral
is florite which adsorbs water rapidly and does not swell or disintegrate in
water. Consequently, it was, and still is, used for the drying of gases and
organic liquids. The early practice was to utilize beds of florite at room
temperature through which was pumped the organic liquid containing
moisture. Reactivation of the bed was accomplished by applying a vacuum
and heating by means of steam coils located within the bed. Alternatively,
the beds were reactivated by circulating an inert gas through the adsorbent,
the desorbed water being condensed on emergence from the bed in cooled
receptacles.
Some types of carbon were in common use for decolourizing and
removing odours from a wide variety of materials. Carbons were also used
for treating water supplies. The decolourization of liquids, including the
refining of sugar melts, was accomplished by mixing the carbon adsorbent
with the liquid to be bleached and subsequently filtering. In some cases the
residual adsorbent was regenerated for further use by passing steam through
a bed of the spent adsorbent. In the case of water treatment, non-potable
waters were either percolated through beds of carbonaceous adsorbent, or
activated carbon was added to water in mixing tanks. The resulting effluent
was then treated with chlorine to remove toxins. Alternatively, the
contaminated water was first treated with excess chlorine and then allowed