Assessing Reuse Potential of TEDA-Impregnated Activated Carbon Through Physicochemical Characterization and CH3I Breakthrough Test

Triethylenediamine (TEDA)-impregnated activated carbon (AC) is widely used in the air purification systems of nuclear power plants to retain gaseous radioactive species. Regeneration and reuse of spent AC may reduce radioactive waste management burdens, but the recovery of adsorption-relevant properties after treatment requires experimental evaluation. This study evaluated whether a single thermochemical treatment followed by TEDA re-impregnation could recover adsorption-relevant properties and CH3I-capture functionality. Four AC states were comparatively characterized using N2/CO2 physisorption, elemental analysis, XPS, XRD, and TGA, with one determination per applicable sample condition. Thermochemical treatment restored approximately 95% of the BET surface area and micropore volume relative to fresh AC. Nitrogen-based TEDA-equivalent loadings were 5.96 wt% for the initially impregnated Sample 2 and 5.30 wt% for the re-impregnated Sample 4. In single-run CH3I breakthrough tests under modified laboratory-scale conditions, the 5% breakthrough times were 3861 and 4949 min/g respectively. These results indicate first-cycle recovery of measurable CH3I-capture functionality after thermochemical treatment and re-impregnation. However, the results do not constitute ASTM D3803 qualification, and further replicate, control, multi-cycle, and long-term validation is required before practical reuse can be assessed.