球形活性炭中氡的解吸附研究

Study of Radon Desorption in Globular Activated Carbon

由于存在与温度密切相关的解吸附现象,活性炭中的氡并不是按氡的衰变规律衰减,从而对活性炭测氡结果和活性炭降氡效果产生影响。为了测量活性炭氡解吸附速率随温度变化的规律,我们设计了一组实验,对不同温度(20℃~120℃)条件下球形活性炭氡的解吸附进行了测量与计算,结果表明:活性炭中的氡仍然以负指数规律衰减,该实测结果与理论计算相吻合;其中氡的解吸附速率(即解吸附系数λ D)随温度升高而增大,并且呈现较好的线性关系。可见,在进行活性炭测氡实践时,吸附了氡的活性炭在测量前和测量过程中一定要进行密封;在使用活性炭作为去氡吸附剂时,活性炭解吸附问题应该引起足够的重视。

The reduction of radon in activated carbon does not depend on radioactive decay alone due to the radon desorption which is closely related to temperature, which influences the radon measurement and radon reduction of activated carbon. Purpose： The experimental device is designed to investigate the temperature dependence on the radon desorption rate. Methods： A series of experiments were performed at the temperature range from 20~C to 120~C. Results： The result indicates that there are negative exponential function between the y counts of radon in activated carbon and time. This result agrees with the theoretical result. The desorption coefficient h D increases with the rise of the temperature. There is a good linear relationship between h D and temperature. Conclusions： The activated car- bon having adsorbed radon must be sealed before and during the measurement. When using activated carbon as a radon adsorbent, its desorption problem should be given enough atter/fion.