Adsorption characteristics of radon on pre-oxidized nitrogen-doped activated carbon

Abstract

Radon (Rn) is an important carcinogenic factor, and activated carbon (AC) is a commonly used industrial adsorbent for Rn removal at present. However, the adsorption efficiency of conventional activated carbon is relatively low, and is greatly affected by its pore size distribution and chemical functional groups. Therefore, enhancing the adsorption capacity of AC remains a challenge. In this study, the performance of urea-oxidation modified AC as an adsorption material for removing radon gas in the environment is investigated. Urea is an environmentally friendly primary amine. Pretreatment with oxidants (K₂FeO₄ and H₂O₂) promotes the incorporation of nitrogen into activated carbon, and heat treatment changes the pore size distribution of activated carbon, thereby effectively capturing radon gas. The radon adsorption coefficients of the optimized FeN-AC and HN-AC are 173.9% and 140.9% higher than those of the unmodified AC, and 28.7% and 13.2% higher than those of the nitrogen-doped modified N-AC, respectively. Through the comparative analysis of theoretical and experimental results, the adsorption mechanism of radon was analyzed, the relationships between the radon adsorption performance of samples and pore size, specific surface area and nitrogen and oxygen contents were determined, and the scientific effectiveness of pre-oxidation treatment in improving nitrogen doping efficiency was verified. This study provides a theoretical basis and experimental methodology for enhancing the radon adsorption performance of AC.