STUDY OF THE SORPTION PROPERTIES OF NEUTRON-IRRADIATED SILICA GEL

Previous studies on the effect of gamma radiation on silica gel yielded contradictory results; therefore the changes caused by exposure to gamma rays and neutron beam in the sorption capacity of the material, were investigated. The gel, which was washed with HCl and HNO/sub 3/ and dried at 170 deg C, contained 8.4 micromoie/m/sup 2/ of structural water. It was exposed simultaneously to a 2 x 10/sup 12/ n/cm sec neutron beam and to gamma radiation of about 10/sup 7/ r/hr. The duration of the test series was 2.1 and 20 hours. The samples were heated up to 50 deg C during the exposure. After the irradiation the samples acquired an activity of 1.5 microcurie. caused by the Si/ sup 31/ formed. The gel became strongly yellowish, keeping the coloration for more than 5 months. The sorption capacity was measured by comparing the adsorbed Ca/sup 2+/ and methyl blue before and after the irradiation. It was found that the sorption capacity decreased proportionally with the duration of the exposure. The effect was attributed to the irreversible dehydration of the silica gel by the radiation. (TTT)