Synthesis of 8-Hydroxyquinoline/exchanged Montmorillonite Hybrids: Sorption, Luminescence and Thermal Stability Studies

Hybrids (H) prepared from 8-Hydroxyquinoline (8-HQ, "oxine") and exchanged montmorillonites (Na(I)-, Zn(II)- and Fe(III)-Mont) have been synthesized using solid-solid reactions at room temperature. The characterization of these hybrids by PPXRD has shown that the interlayer spaces swell (from 0.22 to 1.10 Å of d001 differences) after the inclusion of 8-HQ due to its complexation with the cations present. In the IR spectra, new bands corresponding to 8-HQ groups, appear in the regions 1244 - 1608 cm-1 and 574 - 826 cm-1. DSC measurement has shown the hybrids to be more stable than the precursor montmorillonites, 8-HQ and the simple metal oxinates. Zeta potential measurement on suspensions of the hybrids showed them to be negatively charged over the whole pH range (pH=2-10). As an application of our elaborated hybrids, sorption of the cationic dye methylene blue MB (CMB=200 mg.L-1) by the Na(I)-, Zn(II)- and Fe(III)-hybrids has been found to be rapid for the first two. At the same time, for the Fe(III) species, one month of sedimentation was required to adsorb 87 % of MB. The structural characterization of multi-hybrids MH (H+MB) by PXRD has shown a shift of d001 to higher values (Na-MH: 15.32 Å; Zn-MH: 16.61 Å; Fe-MH: 16.99 Å), signifying the intercalation of MB into interlayer spaces.