Effect of acidity in the removal-degradation of benzene in water catalyzed by Co-MCM-41 in medium containing hydrogen peroxide

In this manuscript, MCM-41 and Co-MCM-41 were synthesized to evaluate the effect of the metal incorporated in the structure of the mesoporous material used in the benzene removal in aqueous medium containing hydrogen peroxide (H2O2). The decomposition of H2O2 in the medium containing MCM-41 and Co-MCM-41 was investigated. The techniques used to characterize these materials showed satisfactory results, proving that the synthesis was effective. The decomposition of hydrogen peroxide carried out in the ultraviolet/visible molecular absorption spectrophotometer revealed that the pH of the medium and the presence of cobalt influence its decomposition. In the reaction containing benzene + Co-MCM-41 + H2O2, it was possible to confirm this information, because there was practically no decomposition at pH = 1.5, 3.0 and 5.0, whereas decomposition was considerable at pH = 7.0 and 10.0 and all H2O2 was decomposed at pH = 12. Tests containing benzene + H2O2 + MCM-41 resulted in a higher removal of analytes in an alkaline medium. The last catalytic tests contained benzene + Co(II) + H2O2 in the aqueous reaction medium; compared to benzene + Co-MCM-41 + H2O2, it was found that the influence of Co-MCM-41 can be better viewed in pH = 10.0 and 12.0, because 82.1% of benzene was removed after 5 h. (C) 2017 Elsevier Inc. All rights reserved.