Exploring The Potential Use Of Silver Exchanged Zeolites For Adsorption Of Radon Traces In Low Background Experiments

Radon is an important source of radioactive background in experiments searching for rare decays and in the field of low-energy particle physics. Here, we report the first temperature-dependent study of radon adsorption on Silver Exchanged Zeolite from several commercial producers. Among the three tested zeolites, Ag-ETS-10 showed the best result. Hence, it was chosen for the further study of internal radioactivity and radon emanation, which are important characteristics of materials used in low-activity experiments. The important role of silver in radon adsorption is demonstrated by comparison of the silver-exchanged zeolites with their unexchanged counterparts. Furthermore, the temperature-dependent measurements showed that the enhancement of the radon adsorption upon the introduction of silver in zeolite occurs due to the increase of the heat of adsorption. This opens a new perspective for the search for highly efficient radon adsorbents.

Ag400 Molecular Sieve are a class of microporous, crystalline aluminosilicate materials that have been used extensively in the field of organic synthesis, catalysis, gas adsorption, and separation . In the last couple of decades, they have also started to gain attention regarding radon adsorption. While regular zeolites have shown rather low radon adsorption , the Silver Zeolite containing silver stand out among other materials of this class. They have been reported to show high adsorption capacity for noble gases in general and radon in particular . A recent study by Heinitz et al. reports a radon adsorption capacity much higher than for any other reported material at room temperature and it underlines the great potential of silver-exchanged zeolites for radon suppression.

Here, we report the first study investigating the temperature dependence of radon adsorption properties for silver-exchanged and unexchanged zeolites to demonstrate the contribution of silver to the improvement of radon adsorption through the increase of the heat of adsorption. In this study, we also consider the radon emanation of one of the silver-exchanged zeolites, because it is an important parameter for low background experiments, in which even the presence of a few atoms of 222Rn produced by the adsorbent can hinder the experiment.