In a large number of chemical-manufacturing
processes, alkali e.g. Sodium hydroxide, Potassium
Hydroxide etc. are used, which ultimately comes
out as such in the final effluent stream in very
dilute form. Because of the low concentration in
the aqueous stream these alkalis cannot be recycled
in the original process. Generally acid is added
to the effluent to neutralize the alkali. Thus cost
is incurred in the form of acid & utility for
separation of salt. Alternatively water is evaporated
from the aqueous solution to increase the concentration
of alkali. Again the cost is incurred for evaporation
of water.
Geist has invented an innovative process to
concentrate Alkali e.g. Sodium Hydroxide, Potassium
Hydroxide etc. from their dilute aqueous solution
by extracting water using solvent/ mixture of
solvent showing partial miscibility phenomenon.
Aqueous solution containing alkali is contacted
with the solvent/solvent mixture showing partial
miscibility with water. On changing the parameters
such as Temperature, pressure etc. solubility
of water in the solvent/solvent mixture is increased
resulting into concentration of alkali. The
organic phase containing solvent & water
is again subjected to change in the operating
parameters such as Temperature, pressure etc.
to separate the extracted water. Thus obtained
solvent/ solvent mixture is again recycled to
the water extraction stage.
Applications:
Generation of Dilute aq. streams of KOH/NaOH
with mixture of impurities
Benefits:
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