Characterization of Interlayer Cs⁺ in Clay Samples Using Secondary Ion Mass Spectrometry with Laser Sample Modification

Abstract

Ultraviolet laser irradiation was used to greatly enhance the secondary ion mass spectrometry (SIMS) detection of Cs(+) adsorbed to soil consisting of clay and quartz. Imaging SIMS showed that the enhancement of the Cs(+) signal was spatially heterogeneous: the intensity of the Cs(+) peak was increased by factors up to 100 for some particles but not at all for others. Analysis of standard clay samples exposed to Cs(+) showed a variable response to laser irradiation depending on the type of clay analyzed. The Cs(+) abundance was significantly enhanced when Cs(+)-exposed montmorillonite was irradiated and then analyzed using SIMS, which contrasted with the behavior of Cs(+)-exposed kaolinite, which displayed no Cs(+) enhancement. Exposed illitic clays displayed modest enhancement of Cs(+) upon laser irradiation, intermediate between that of kaolinite and montmorillonite. The results for Cs(+) were rationalized in terms of adsorption to interlayer sites within the montmorillonite, which is an expandable phyllosilicate. In these locations, Cs(+) was not initially detectable using SIMS. Upon irradiation, Cs(+) was thermally redistributed, which enabled detection using SIMS. Since neither the illite nor the kaolinite is an expandable clay, adsorption to inner-layer sites does not occur, and either modest or no laser enhancement of the Cs(+) signal is observed. Laser irradiation also produced unexpected enhancement of Ti(+) from illite and kaolinite clays that contained small quantities of Ti, which indicates the presence of microscopic titanium oxide phases in the clay materials.

Preparation of Highly Exfoliated Epoxy/Clay Nanocomposites by “Slurry Compounding”: Process and Mechanisms

“…In addition, the presence of organic adsorbates is observed as well. A relatively abundant example is observed at m / z 41, similar to the organic ions reported by Groenewold and co-workers with clay . When the clay was modified with APTMS, new ions with m / z 29 and 30 are observed in the ToF-SIMS spectrum, which corresponds to elemental compositions of CH 3 N and CH 4 N, respectively.…”

Study of Physical, Chemical and Morphological Alterations of Smectite Clay upon Activation and Functionalization via the Acid Treatment

“…Mineral acids like HCl and H 2 SO 4 can solve and separate the alumina layer of the clay. Eisele (1982) introduced the bleaching of the clay by mineral acids as a new method for producing aluminum metal [2,3].…”

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].…”