Study of the structural modifications in activated clays by Mössbauer spectroscopy and X-ray diffractometry
In this work we study the changes induced on the structure of a smectite clay by chemical acid activation with HCl using X-ray diffractometry (XRD) and transmission Mössbauer spectroscopy (TMS) techniques. By XRD we were able to determine the mineralogical composition of the clay samples and measure the changes in the interplanar distance associated to the structural modifications in the clays. We measured a reduction in the interplanar distance and reflection intensity as the acid concentration in the activation process increased. TMS allowed us identify and characterize the structural sites occupied by ferric and ferrous iron cations. In addition, we were able to monitor the effects caused by the chemical acid activation on the valence state of the iron cations that occupy these structural sites in the clay. For the treatment at low acid concentration, keeping time and temperature of activation constant, our results showed a strong effect on the ferrous and ferric iron sites, reducing and increasing their adsorption relative areas respectively.
KeywordsSmectite Chemical acid activation X-ray diffractometry Interplanar distance Transmission Mössbauer spectroscopy
Unable to display preview. Download preview PDF.
- 1.Moore, D.M., Reynolds Jr, R.C.: X-Ray Diffraction and the Identification and Analysis of Clay Materials, 2nd edn. Oxford University Press, Oxford (1997)Google Scholar
- 2.Volzone, C., Porto Lopez, J.M., Pereira, E.: Acid activation on smectitic material: I. structural analysis. Rev. Latinoamericana. Ing. Quím. Apl. 16, 205–215 (1986)Google Scholar
- 3.Brand, R.A.: Normos Mössbauer Fitting Program, User’s Guide. Wissenschaftlich Elektronik GmbH, Starnberg (1995)Google Scholar
- 8.Volzone, C., Zalba, P.F., Pereira, E.: Activación ácida de esmectitas. II estudio mineralógico. An. Soc. Quím. Argent. 76, (1), 57–68 (1988)Google Scholar