Evaluation performance of Fe–Mn–Ce–O mixed metal oxides and Fe–Mn–Ce–O/Montmorillonite for adsorption of azo dyes in aqueous solution and oxidation reaction

Abstract

The present study focused on synthesis of A–Fe–Mn–Ce–O, B–Fe–Mn–Ce–O and B–Fe–Ce–Mn–O/montmorillonite (B–Fe–Ce–Mn–O/MMT), (A and B differ in the method of preparation). The structure and morphology of the as-synthesized nanocomposites were characterized by FTIR, FESEM, XRD and EDX. The adsorption behavior of the prepared samples was tested through elimination of MB and RhB from aqueous solution. The effect of different parameters namely amount of adsorbent, pH, contact time, temperature, thermodynamics and equilibrium of adsorption were investigated. Based on the results, for A–Fe–Mn–Ce–O and B–Fe–Mn–Ce–O/MMT the adsorption process is endothermic, spontaneous and langmuier isotherm model best fitted the data. Comparison of the maximum adsorption capacity obtained for the adsorption of MB on synthetic adsorbents is as follows: B–Fe–Mn–Ce–O/MMT > A–Fe–Mn–Ce–O > B–Fe–Mn–Ce–O. In the next step, A–Fe–Mn–Ce–O, B–Fe–Mn–Ce–O and B–Fe–Ce–Mn–O/MMT were applied as catalysts in oxidation reaction. The investigation revealed that A–Fe–Mn–Ce–O catalyzed oxidation of benzyl alcohol with H2O2 as green oxidant yielded benzaldehyde (<99% selectivity) with 99% conversion. It was found that with B–Fe–Mn–Ce–O as catalyst, <99% conversion was achieved to <99% selectivity for 1-Phenyl-1,2-ethanediol. Comparison of the catalytic activity of the nanoparticles obtained in the oxidation reaction is as follows: A–Fe–Mn–Ce–O > B–Fe–Mn–Ce–O > B–Fe–Mn–Ce–O/MMT.