IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Experimental-theoretical study of Sr sorption in Na-montmorillonite
Autor/es:
A. GIL REBAZA; R. BASTIDAS BRINCEÑO; M. TAYLOR; V. DÍAS DE ROSA; L. A: ERRICO; L. MONTES; R. ALONSO
Lugar:
Cartagena
Reunión:
Conferencia; ICTP Caribbean School on Materials for Clean Energy; 2019
Institución organizadora:
International Centre for Theoretical Physicvs (ICTP)
Resumen:
Pollutant releases into the environment is an important issue related to modern life. Industries such as metallurgical, petrochemical, electronic, paint and pigment, and other human activities are a very important source of heavy metals in effluents. The pollution originated in these environmental matrices must be detected so early as possible and, if necessary, their remediation must be taking into account. In particular, cesium, cobalt and strontium are heavy metals that can be released into the environment during nuclear accidents. Their potential toxicity makes essential to removed them from contaminated effluents.A widely extended remediation technologies are based on the sorption of contaminants. Among the sorbent materials, clay minerals such as montmorillonite (MMT), are well ranked. Montmorillonite clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M=Na, Ca, Fe, etc.) in its interlayer space. The present work resumed the preliminary results of a theoretical-experimental approach study of Sr sorption in Na-MMT, Na0.41[(MgAl3O8(OH)4 (Si8O12)]2 .n(H2O). Experimentally, Sr adsorption tests were carried out under batch conditions (V = 25 mL, Sr concentration 100 mg/L, pH = 6, S/L=5 g/L). After the test, solid and liquid phases were separated by centrifugation and the solid one were analyzed using X-ray diffraction (Cu-Kα) to determine the position of the reflection peak d001 (partial diffractograms-semioriented samples). Sr adsorption was quantifying by difference between the initial and equilibrium concentration, using ICP- masses. The obtained adsorption percentage was 80 ± 4%.From the theoretical point of view, all calculations have been performed in the framework of the Density Functional Theory, using the pseudopotential and plane-wave method (Quantum Espresso code), exchange-correlation part has been described with GGA-PBE parameterization, and van der Waals corrections was considered (rVV10). In order to evaluate if the Sr sorption is favored, total energies and energies of formation were calculated. Furthermore, we have determinate the electric field gradient in different atoms using the GIPAW method. We have considered the MMT pristine (Na-MMT), and the model assumed was based on the replacement of Na atoms located in the inter-layers by Sr atoms coordinated with nH2O molecules (n=4, 6, 8, 10). For each case, atomic positions and cell parameters has been optimized in order to get the energy of formation at the equilibrium. The basal spacing d001 for the optimized structures were also calculated and compared with the experimental one, being the value well reproduced. Comparison of Sr sorption with Co sorption (previous study) was also discussed.