Radon Adsorption Performance of Metal-Loaded Bamboo Activated Carbons with Different Pore Structures

Radon (Rn) is a radioactive inert gas, a major source of natural radiation exposure to humans, and a leading cause of lung cancer in nonsmokers. In this study, a method combining micropores and metal sites was employed. Bamboo activated carbon, modified with alkali treatment to create different pore structures, was selected as the carrier, onto which silver and nickel metals were loaded. The goal was to optimize the loading amount and improve the Rn adsorption performance of the bamboo activated carbon, developing a highly efficient Rn adsorbent. Nickel nitrate impregnation treatment created micropores in the carrier, while silver nitrate obstructed the micropore structure. The optimal impregnation concentration varied depending on the pore structure of the carrier. After nickel was loaded onto the unmodified BC, the Rn adsorption coefficient increased. For the alkali-modified BCK0.75, which has the highest proportion of key pore volume for Rn adsorption, silver loading led to a decrease in the Rn adsorption coefficient. However, for the alkali-modified BCK1.5, which has pore sizes larger than the key size for Rn adsorption, the Rn adsorption coefficients increased after loading with nickel and silver, reaching 11.36 ± 0.21 and 9.25 ± 0.12 L/g, respectively representing improvements of 75.58 and 42.97%. Additionally, the proportion of micropore volume at 0.77 nm in Ni_0.3@BCK1.5 was higher than that in BCK0.75. After five cycles of heating regeneration under nitrogen, Ni_0.3@BCK1.5 and Ag_0.6@BCK1.5 maintained 93.88 and 92.48% of their original Rn adsorption coefficients, respectively. Ni_0.3@BCK1.5 not only contains metal sites but also retains the key pore size for Rn adsorption, which has good application value in Rn removal.