International Journal of Materials Engineering and Technology
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Abstract: Charcoal, used for the removal of gaseous radioiodine
in the Filtered Air Discharge systems of nuclear power reactors, is impregnated
with triethylenediamine (TEDA) to increase its efficiency for trapping organic
iodides. The adsorption of on TEDA charcoal occurs through both
reversible physisorption and irreversible chemisorption. Under a specified flow
condition and filter geometry, the key parameters affecting filter efficiency
are the adsorption rate constant and adsorption capacity. Adsorption rate
constants were determined using a similar set-up to that recommended by the
ASTM, but monitoring both the 131I activity distribution along a bed
of TEDA charcoal, and the 131I activity release from the bed,
following a short-term small-mass loading with 131I-labeled Adsorption capacities were
determined from breakthrough measurements of the front during loading up to saturation, followed
by purging until no further release was observed. Using these methods, the rate
constants and the capacities of the physical and chemical adsorption were
established as a function of TEDA content of the charcoal and relative humidity.
Approximate analytical solutions of a mathematical model, consisting of transport and its adsorption-desorption
on TEDA charcoal, under the experimental conditions are also presented to relate
the measurements to the adsorption parameters.
Keywords and phrases: charcoal filter, radioiodine, adsorption, removal efficiency.
