EGU2020-1394
https://doi.org/10.5194/egusphere-egu2020-1394
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cr6+ adsorption by modified vermiculite

Valeria Medoro1, Celia Marcos Pascual2, Giacomo Ferretti1, Giulio Galamini1, and Massimo Coltorti1
Valeria Medoro et al.
  • 1University of Ferrara , Department of Physics and Earth Sciences, Ferrara, Italy (valeria.medoro@unife.it)
  • 2University of Oviedo. Department of Geology, Oviedo, Spain (cmarcos@uniovi.es)

Abstract: Cr6+ adsorption by modified vermiculite

 

Valeria Medoro- University of Ferrara , Department of Physics and Earth Sciences, Italy

Celia Marcos Pascual-University of Oviedo, Department of Geology, Spain

Giacomo Ferretti- University of Ferrara , Department of Physics and Earth Sciences, Italy

Giulio Galamini- University of Ferrara , Department of Physics and Earth Sciences, Italy

Massimo Coltorti- University of Ferrara , Department of Physics and Earth Sciences, Italy

 

This work aimed at investigating the adsorption of Cr6+ in water by exfoliated vermiculite. The adsorbant tested in this experiment was a vermiculite (from China) which has been subjected to heating at 1000 °C for 1 minute, resulting in an exfoliated vermiculite.

Three effects were studied: 1) contact time; 2) initial concentracion of Cr6+; 3) adsorbent mass. Samples were analysed by X Ray Fluorescence (XRF), X Ray Diffraction (XRD) and the solutions with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to quantify the adsorbed Cr6+ by the vermiculite.

Results from XRD diffraction showed a conversion of vermiculite into flogopite  after heating at 1000°C for 1 minute because of: 1) high content of potassium, 2) dehydration and 3) structural re-ordering; after the contact of vermiculite with Cr6+, the mineral structure did not change. The adsorption of Cr6+ was studied by Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. DKR model, indicative of a cooperative process, described adsorption equilibrium better than the other two models and the maximum adsorption capacity obtained was of 2.81 mol/g. Kinetic was studied using pseudo-first and pseudo-second order kinetic models, with a better description of the process by pseudo-second order model with correlation coefficient almost unitary (R2=0.9984; other kinetic parameters were k2=0.0015 and the absorption initial rate of 0.2x10-8 mg g-1 h-1). 

The present study demonstrates the effectiveness of modified vermiculite adsorbents for the treatment of hexavalent chromium-contaminated waters and that its adsorption depends on the experimental conditions (such as contact time, initial concentracion of Cr6+ and adsorbent mass).

How to cite: Medoro, V., Marcos Pascual, C., Ferretti, G., Galamini, G., and Coltorti, M.: Cr6+ adsorption by modified vermiculite, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1394, https://doi.org/10.5194/egusphere-egu2020-1394, 2019

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