The Effect of Weathering on Charcoal Filter Performance: II. The Effect of Contaminants On The CH₃I Removal Efficiency of Teda Charcoal

The effect of various contaminants, namely NO₂, SO₂, 2-butanone [methyl-ethyl-ketone (MEK)], and NH₃, on the radioiodine removal efficiency of triethyl-enediamine (TEDA)-impregnated charcoal filters has been studied, and an attempt was made to characterize and quantify the weathering process of TEDA charcoal by these contaminants. The effects of the contaminants on the CH₃I removal efficiency of TEDA charcoal under dry and humid conditions are described. Based on our results, the efficiency of TEDA charcoal is degraded most by NO₂ and SO₂, NH₃ has a negligible effect, and MEK produces a mild degradation. The degree of degradation parallels the contaminant’s ability to be chemisorbed on the TEDA impregnant. The combined effect of water vapor and a contaminant on the charcoal efficiency is different for each contaminant. Nitrogen dioxide adsorbed under dry conditions is more effective in degrading the CH₃I removal efficiency of the charcoal than when adsorbed under humid conditions. On the other hand, a completely opposite result is observed for SO₂. The MEK contaminant behaves similarly to SO₂, but the effect of humidity was less significant than for SO₂. Ammonia has no effect on the efficiency of the charcoal regardless of humidity.