Authors:Shitong Yang, Donglin Zhao, Guodong Sheng, Zhiqiang Guo and Yubing Sun
In this work, a series of batch experiments were carried out to investigate the effect of various environmental factors such
as contact time, pH, ionic strength, coexisting electrolyte ions, humic substances and temperature on the sorption behavior
of illite towards 64Cu(II). The results indicated that 64Cu(II) sorption on illite achieved equilibrium quickly. The pH- and ionic strength-dependent sorption suggested that 64Cu(II) sorption on illite was dominated by ion exchange or outer-sphere surface complexation at pH < 7, whereas the pH-dependent
and ionic strength-independent sorption indicated that the sorption process was mainly attributed to inner-sphere surface
complexation at pH > 7. A positive effect of humic substances on 64Cu(II) sorption was found at pH < 6.5, whereas a negative effect was observed at pH > 6.5. The Langmuir and Freundlich models
were used to simulate the sorption isotherms of 64Cu(II) at three different temperatures of 293, 313, and 333 K. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) of 64Cu(II) sorption on illite were calculated from the temperature dependent sorption isotherms, and the results indicated that
the sorption of 64Cu(II) on illite was endothermic and spontaneous. From the experimental results, it is possible to conclude that illite has
good potentialities for cost-effective treatments of 64Cu(II)-contaminated wastewaters.
Authors:Liu Xia, Chen Yuantao, Chi Yaling, Guo Zhijun and Cai Linsen
In this article, a series of batch experiments were carried out to investigate the effect of various environmental factors
such as contact time, solid content, pH, ionic strength, foreign ions, temperature and coexisting humic acid on the sorption
behavior radionuclide 60Co(II) on illite. The results indicated that the sorption of Co(II) was strongly dependent on pH, ionic strength and temperature.
At low pH, the sorption was dominated by outer-sphere surface complexation and ion exchange on illite surfaces, whereas inner-sphere
surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models
were used to simulate the sorption isotherms at three different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic
data (∆G0, ∆S0, ∆H0) were calculated from the temperature dependent sorption isotherms and the results suggested that the sorption process of
Co(II) on illite was an endothermic and spontaneous process. The sorption test revealed that the illite can be as a cost-effective
adsorbent suitable for pre-concentration of Co(II) from large volumes of aqueous solutions.
Adsorption of strontium on illite type clay has been studied as a function of shaking time, the ratio of solution volume to weight of clay and the concentration of adsorbate, using 90Sr as a tracer. The adsorption experiments were carried out using the batch method and initial Sr2+ ion concentrations ranged from 10–6 to 10–1 M. The influence of Ca2+ and Ba2+ cations on Sr adsorption were also studied. These effects are correlated with the ionic radii of alkaline earth ions present in the solution. The Freundlich and Dubinin Radushkevich (D-R) isotherm have been applied to the data and the parameters of the isotherm equations were calculated. The mean energy of adsorption, E was also calculated from the adsorption energy constant, K and maximum capacity Xm values were determined from linearized D-R equation. From empirical Freundlich parameters a site distribution function was calculated.
The sorption of Ba2+ ion on natural kaolinite and chlorite-illite clays was investigated at different initial concentrations and temperatures
using the radiotracer method. The sorption data were well described by Freundlich and Dubinin-Radushkevich isotherms. Ba2+ sorption on both clays showed an exothermic behavior with ΔH° (kJ/mol) values being -7 and -5 for sorption on kaolinite and chlorite illite mixed clay, respectively. The ΔG° values indicate that the sorption was spontaneous with sorption energies corresponding to ion-exchange type sorption. X-ray
diffraction studies showed that no significant change in the matrix of the clays occurred upon Ba2+ sorption.
Authors:Ivett Kovács, Tibor Németh, Gabriella B. Kiss and Zsolt Benkó
XRD analysis is difficult. Occasionally, due to the high value of the objects, no or only very limited sampling is permitted (e.g. archaeological artefacts or planetary materials). Structural characterization of clay minerals – e.g. illite polytypism
Authors:Andrea Varga, György Szakmány and Béla Raucsik
reflections of clay minerals. - Annual Report of Hung. Geol. Inst, for 1972, pp. 229-256. (In Hungarian).
Środoń, J. 1980: Precise identification of illite/smectite interstratifications by X-ray powder diffraction. - Clays and Clay
Authors:Young-Hwan Cho, Chan-Ho Jeong and Pil-Soo Hahn
The sorption behavior of137Cs onto kaolinite, bentonite, illite, and zeolite was studied at different ionic strengths of Na+, K+, Ca2+. A significant effect of ionic strengths on the sorption has been observed. Clay minerals with 21 structure (bentonite, illite) showed much higher sorption than that of 11 structure (kaolinite). Zeolite showed high selectivity for137Cs sorption. Sorption behavior of137Cs on clay minerals can be explained by their surface charge characteristics originated from mineral structure.
Authors:H. Göktürk, C. Eylem, S. Hatipoĝlu and H. Erten
The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.90Sr (29.1 y) and133Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioRd, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K+, Sr2+, Ca2+ and Al3+ ions, respectively, prior to sorption studies with Ba2+ ions. The results of Ca2+ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba2+ ion exchanges primarily with the Ca2+ ion on the clay minerals.