Pillaring of synthetic hectorite by mixed [Al_13-xFe_x] Pillars

Abstract

Abstract The pillaring of a Laponite by alumina pillars, iron pillars and mixed Al-Fe pillars was obtained by a simple in situ method starting from AlCl 3 and/or FeCl 3 solutions with different molar ratio Fe/(Fe + Al), and from NaOH solution added simultaneously to the clay suspension. The Al 13 pillars were evidenced by XRD and NMR spectra. The density and the charge of these pillars were calculated from the chemical analysis. The Fe pillars (in samples with Fe content >26%) are larger than Al 13 pillars and slowly reducible by hydrogen temperature programmed reduction (H 2 TPR), but we do not have any information on their structure. There is also an excess of non-pillar Fe retained by the pillared clays probably as oxyhydroxides. The isomorphic substitution in the mixed (Al-Fe) 13 pillars (in samples with an Fe content >26%) was evidenced by H 2 TPR results compared to the chemical analyses and by the interpretation of the 27 A1 peaks in the NMR spectra.