Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9674433 | Journal of Hazardous Materials | 2005 | 7 Pages |
Abstract
The objective of the present study was to investigate the adsorption of the heavy metals mercury(II) and chromium(VI), from aqueous solutions, onto Moroccan stevensite. A mineralogical and physicochemical characterization of natural stevensite was carried out. In order to improve the adsorption capacity of stevensite for Cr(VI), a preparation of stevensite was carried out. It consists in saturating the stevensite by ferrous iron Fe(II) and reducing the total Fe by Na2S2O4. Then, the adsorption experiments were studied in batch reactors at 25 ± 3 °C. The influence of the pH solution on the Cr(VI) and Hg(II) adsorption was studied in the pH range of 1.5-7.0. The optimum pH for the Cr(VI) adsorption is in the pH range of 2.0-5.0 while that of Hg(II) is at the pH values above 4.0. The adsorption kinetics were tested by a pseudo-second-order model. The adsorption rate of Hg(II) is 54.35 mmol kgâ1 minâ1 and that of Cr(VI) is 7.21 mmol kgâ1 minâ1. The adsorption equilibrium time for Hg(II) and Cr(VI) was reached within 2 and 12 h, respectively. The adsorption isotherms were described by the Dubinin-Radushkevich model. The maximal adsorption capacity for Cr(VI) increases from 13.7 (raw stevensite) to 48.86 mmol kgâ1 (modified stevensite) while that of Hg(II) decreases from 205.8 to 166.9 mmol kgâ1. The mechanism of Hg(II) and Cr(VI) adsorption was discussed.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Health and Safety
Authors
A. Benhammou, A. Yaacoubi, L. Nibou, B. Tanouti,