Etude d’une argile locale du Burkina Faso à des fins de décontamination en Cu2+, Pb2+ et Cr3+

Journal de la Société Ouest-Africaine de Chimie 06/2011; 031:49 - 59.


Water and wastewater studies in Burkina Faso have revealed high levels of heavy metals in most streams and other water bodies particularly within urban areas and mining society’s area. The metals are produced and released by anthropogenic source during industrial and agricultural activities, and also in vehicular emissions. These metals may pose serious threats to both human health and the environment. This study investigated the potential of natural mixed clay, KORO, from Burkina Faso, in removing, Cu2+, Pb2+, and Cr3+ cations from aqueous solutions using batch equilibrium technique. Qualitative mineralogical characterisation of the clay by XRD revealed that the clay contains montmorillonite, quartz, albite, illite, kaolinite, goethite and orthose. pHpzc for the clay, as determined by potentiometric titrations, was 7.31. pH metal sorption dependence of the clay revealed that for an aqueous solution of 0.06 mol/l, 0.048 mol/l and 0.096 mol/l respectively in Cu2+, Pb2+ and Cr3 removal of 96.76 %, 96.59 % et 100 % respectively are obtain at the following pH: for Cu2+ at pH 8.5, pH 8.4 for Pb2+ and pH 5,96 for Cr3. More than 52.7 %, 96 % et 86 % of the removal of Cu2+, Pb2+ and Cr3+ are attributable to adsorption on the clay while the remaining, hydroxides precipitation as well as complexation phenomenon may contribute to the removal of the heavy metal cation. Inner sphere complex formation is expected.

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    ABSTRACT: Clay–polypyrrole–silver hybrid material was synthesized via one pot photopolymerization of pyrrole using silver nitrate as a photosensitizer in the presence of clay (montmorillonite, MMT). We have silanized the clay using a pyrrolyl-functionalized silane to provide anchor sites for the polypyrrole/silver composite coating (PPyAg). The silanized clay was effective in the making of a ternary hybrid material (MMT–Sil–PPyAg) which exhibits a PPyAg-rich surface. The polypyrrole and silver mass loadings were estimated to 19 and 27 wt.%, respectively. Interestingly, silanization by pyrrole functionalized silane permits to fully exfoliate the clay upon the photopolymerization process. In contrast, without silanization, the surface of the ternary hybrid material MMT–PPyAg is rather aluminosilicate-rich despite a black colour of the final product. We demonstrate that the anchored Ag particles are in the metallic state. We evaluated the propensity of the PPyAg-modified silanized clay to catalyse the reduction of methylene blue by NaBH4 and found it levels off to 94% within a few minutes only.This work conclusively demonstrate that UV-induced polymerization of pyrrole in the presence of a layered silicate is simple and fast; in addition, it permits to design novel hybrid materials with high catalytic performances
    Full-text · Article · Dec 2013 · Colloids and Surfaces A Physicochemical and Engineering Aspects