Sorption of Nickel and Cobalt on a Size-Fraction of Unconsolidated Glaciofluvial Deposits and on Clay Minerals

Abstract

In earlier studies we investigated the sorption behaviour of cesium, barium and strontium on size fractions of glaciofluvial materials and on the clay minerals montmorillonite, illite and chlorite. Here, we report on sorption and desoiption experiments with nickel and cobalt in synthetic groundwater on the <32 μπι size-fraction of a glaciofluvial deposit, on the clay minerals montmorillonite and illite, and on synthetic Si0 2 and CaC0 3 . In general, sorption and desorption equilibrium is not reached for nickel and cobalt, which is in striking contrast to the behaviour observed for strontium and barium. A significant increase in the distribution ratios was observed for nickel and cobalt up to sorption times of 182 and 56 days, respectively. In most cases, the sorption process was largely irreversible. The sorptive power of the < 32 μπι materials with artificially changed mineralogies is considerably reduced as compared to that of the <32 μπι material with the original mineralogical composition, i. e., during the removal of the carbonates a significant decrease in the sorptive power occurred. A comparison of the sorption behaviour of nickel and cobalt with that of cesium, strontium and barium is also shown.

Metal Ion Sorption and Desorption on Zeolitized Tuffs from the Nevada Test Site

“…This assumption is often valid in the case of organic chemicals, but it is not always justified in the case of inorganic chemicals where sorption may be at least partly irreversible. Sorption and desorption experiments with zinc, nickel, cobalt, strontium, and cesium on natural soils and clay minerals were conducted to estimate the reversibility of sorption and the mobility of metals of concern in an aqueous solution (5,11,22,23). The reversibility of Pb sorption on clinoptilolite was examined as a function of other exchange cations present in the zeolite structure (20).…”

Speciation of Radionuclides in the Environment

“…They found a considerable mobility for "Tc, 60 Co and 233 U which they attributed to low molecular weight anionic complexing. Another plausible explanation could be based on batch laboratory experiments by Griitter et al [223], who found, with selected size fraction of clay minerals and glaciofluvial sediments, that the sorption kinetics of cobalt and nickel is very slow. In contrast, the concentrations of 90 Sr and 137 Cs were extremely low in the groundwater due to an artificial alkaline environment near the trench which enhanced sorption and precipitation of '"Sr, and the strong and selective sorption of 137 Cs to illite.…”