ADSORPTION OF TRITIUM FROM AQUEOUS SOLUTIONS BY PALYGORSKITE

Abstract

The results of experiments using palygorskite from the Cherkasy deposit (Ukraine) and tritiated water (“HTO”) are highlighted. The performed studies provide an assessment of the adsorption of tritium from an aqueous solution and the effect of hydrogen isotope fractionation in a stationary closed system “HTO – palygorskite”. The mechanisms of retention of the superheavy hydrogen isotope in the structure of a natural clay mineral are explained. It is established that the accumulation of tritium is a multi-stage process. It was determined that the adsorption capacity of palygorskite is due to uncompensated charges on the surface of mineral particles, the presence of zeolite and coordination-bound water in the channels, where molecular HTO → H2O exchange between the mineral and tritiated water occurs, as well as ionic OT– → OH– substitution in the octahedral layers of the mineral. The distribution of tritium in four structural positions was determined – in surface-adsorbed, coordination-bound, zeolite and strongly bound forms. The predominance of the strongly bound form (22% of the total tritium content in the mineral) over channel water was revealed. The rationality of using palygorskite for the accumulation of tritium from aqueous solutions was determined.