Study Of Iodine Sorption And Diffusion On Minerals

In this paper ,the performance of adsorbing and retarding 125I (substituted for 129I) for mixed materials as buffer, backfill material was investigated, the distribution coefficient Kds by batch sorption experiments were determined for four kinds of minerals and one kind of bentonite under atmosphere ,iodine sorption and desorption on several mianerals were studied under low oxygen ambience at first time in the domestic, and apparent diffusion coefficient Da of 125I~ was determined for mixed minerals under atmosphere . The Results as follows:Distribution coefficient Kds of 125I" under atmosphere: bentonite is 3.23 ml ?g"1 , chalcopyrite is 72.42 ml ?g"1 , galenite is 118.9 ml ?g"1 , pyrite is 1.93 ml ?g"1 , cinnabar is 55.48 ml ?g"1 ; and the corrresponding Kds under low oxygen ambience: galenite is 88.48 ml ?g"1 , chalcopyrite is 6.47 ml ?g"1. when pH was in the range of 2.25-12.26, Kds of 125I" on chalcopyrite , galenite, pyrite and cinnabar decreased with increase of pH under atmosphere; but Kds of 125I" on galenite increased with increase of pH under low oxygen ambience. Kds of 125I~ on several minerals increased with increase of mineral ratio in mixed materials under atmosphere and low oxygen ambience ; and decreased with decrease of ratio of mixed materials and liquid under atmosphere. Under the same condition, Kds of 125I" on chalcopyrite and galenite were larger than Kds of 125IO3" . For same mineral, desorption of 125I" on it was weaker than 125IO3", and sorption of 125I\ I25IO3" on galenite is irreversible.Apparent diffusion coefficient Da of 125I" in the mixed material were determined by the pass-through diffusion way, Da values under atmosphere was given: Da=7.29X10-12m2 ?s-1 .