TOF-SIMS study of Cs + sorption on natural kaolinite

Abstract

The sorption of Cs q on natural kaolinite has been studied using time-of-flight secondary ion mass spectrometrẙ q Ž . TOF-SIMS . Depth profiling up to 70 A was performed to study the change in the amount of sorbed Cs as a function of depth in the kaolinite matrix. Quantitative determination of the amounts of primary cations in the kaolinite structure before and after sorption of Cs q ions was carried out to identify which cations are possibly taking part in the sorption process. The experimental results showed that large amounts of Cs q are sorbed onto the surface of kaolinite and that sorption decreases sharply over the first 10-A depth. The fact that kaolinite surface was negatively charged under the operating pH indicates that physisorption has an important contribution to the sorption process. The results also showed that Na, Mg 2q and Fe 3q were involved in the sorption process with Cs q and that the total decrease in the amounts of these cations is close to the amount of sorbed Cs q , suggesting that ion exchange is the dominant sorption mechanism. ᮊ

Removal of cesium ions from aqueous solution by adsorption onto local Taiwan laterite

“…This fact reflects the instinct that tight hydrogen bonding between kaolinite layers restricts diffusion of adsorbed Cs to the interlayer sorption sites. This finding is in good agreement with those in other studies, in which Cs adsorption is reported occurring only at the first ten angstroms on the kaolinite surface [19].…”

Physicochemical characterization of the retardation of aqueous Cs+ ions by natural kaolinite and clinoptilolite minerals

“…So far, a variety of studies have been devoted to characterizing various aspects of the sorption behavior of Cs + ion on kaolinite and on clinoptilolite, using a variety of characterization techniques [9][10][11][12][13][14][15][16][17][18]. In our earlier studies, the retention capacity of kaolinite toward Cs + was studied and compared with that of other clay minerals [9].…”

“…In our earlier studies, the retention capacity of kaolinite toward Cs + was studied and compared with that of other clay minerals [9]. A depth profiling study was also carried out to reveal the distribution of Cs + across the surface of kaolinite [10]. The applicability of kaolinite as a reactive barrier for Cs + retention was tested by other authors and the irreversibility of its uptake by kaolinite was discussed and compared with other clay minerals [11,12].…”

ToF–SIMS depth profiling analysis of the uptake of Ba2+ and Co2+ ions by natural kaolinite clay

“…The ideal formula of kaolinite is Al 2 Si 2 O 5 (OH) 4 , and most minerals of the kaolin group appear to be close to ideal in composition. The structure of kaolinite consists of stacked units, each composed of one octahedrally coordinated sheet of aluminum ions and one tetrahedrally coordinated sheet of silicon ions (a 1:1 clay mineral).…”

“…ToF-SIMS was applied earlier to study the sorption behavior of these ions on natural clay samples rich in chloriteillite and bentonite clays [2,3] and of Cs + on natural kaolinite [4]. In dealing with geological samples, the most important difficulty associated with the application of surfacesensitive techniques stems from the heterogeneous nature of such samples.…”