Radon (Rn) is an important contributing factor to lung cancer. Activated carbon (AC) is currently the only Rn adsorbent for industrial applications. However, the effect of the key pore size of AC on Rn adsorption remains unclear, and enhancement of the Rn adsorption performance when using AC is still a challenge. In this work, grand canonical Monte Carlo (GCMC) simulations were performed to simulate the Rn adsorption ability of AC with different pore sizes. The adsorption selectivity of AC with pore sizes from 0.42 nm to 0.60 nm for Rn in the atmospheric environment was much greater than that for nitrogen and oxygen. The Rn adsorption performance was also investigated using KOH-modified activated carbon (KAC) with different pore sizes experimentally prepared using high-temperature roasting. The results showed that when the pore volume of KAC was significantly increased to approximately 0.55 nm, the Rn adsorption performance was obviously improved. Its adsorption coefficient reached 6.50 ± 0.11 m 3 kg −1 , which was 46.7 % higher than that of AC. After heating and regeneration in air, the Rn adsorption performance of KAC was basically unchanged. Combined with the comparative analysis using theoretical and experimental results, the relationship between the Rn adsorption performance of KAC and the pore volume at 0.55 nm is determined, and the accuracy of the GCMC calculation results was substantiated. This research provides a theoretical basis and an experimental method for improving the Rn adsorption performance of AC.
Radon (Rn) is a universally known indoor radioactive gas that poses a significant threat to human health. Activated carbon (AC) is the only commercial Rn adsorbent; its adsorption performance is extremely limited due to too few micropores. A series of nickel nanoparticles supported on AC (Ni/AC) composites, combining abundant micropores with open metal sites, is rationally designed for adsorbing Rn via a two-step process consisting of impregnation and high-temperature reduction. The Rn adsorption performance of the Ni/AC composites is obviously improved due to the introduction of nickel nanoparticles. The adsorption coefficient of Ni/AC calcined at 800 °C reaches 6.56 ± 0.14 m3 kg−1 at 25 °C and 1 bar, 48% higher than that of AC. The Ni/AC Rn adsorption coefficient is similar over five cycles. The fine and homogeneous dispersion of nickel nanoparticles, the appropriate chemical state of nickel and the high content of Ni0 synergistically promote Rn adsorption on Ni/AC. Experiments verify that Ni/AC composites are a promising candidate for the adsorption of Rn in the atmospheric environment.
Radon (Rn) is a radioactive noble gas and one of the primary culprits of lung cancer. Developing efficient adsorbents for Rn removal is of paramount importance, yet remains a daunting challenge due to the weak interaction between Rn and the adsorbent, particularly when low concentrations of Rn are present. Herein, a renewable biomass-derived carbon material consisting of rich ultramicropores was synthesized for record-high Rn adsorption under ambient condition. By meticulously selecting the carbonization precursor, chemical activator, and pyrolysis temperature, the optimized adsorbent, GC-700-2.4, exhibits a narrow pore distribution in the ultramicroporous range (<7 Å). The dynamic adsorption coefficient ( K d ) of GC-700-2.4 is determined to be 9.51 L/g based on radon breakthrough experiments, which is twice the value of the commercial Rn adsorbent, coconut shell activated carbon ( K d = 4.65 L/g), and outperforms all other reported Rn adsorbents under comparable conditions. The superior Rn adsorption performance of GC-700-2.4 is attributed to the narrow ultramicropores in GC-700-2.4 that show enhanced confinement effect toward Rn. Consequently, GC-700-2.4 shows promising potential for practical applications as an efficient and cost-effective Rn adsorbent.
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