Reduction of organic pollutants in a simple binary system catalyzed by mesoporous silica containing metal-metal oxide composites

In this work, the CTA-MCM-41 material was modified by solutions containing a binary mixture of metallic cations (Ag + /Ni 2+ , Ag + /Cu 2+ , and Cu 2+ /Ni 2+ ), then the resulting solids were calcined at 550°C. The obtained materials were characterized by several characterization techniques to determine their structural, textural, and morphological properties. The obtained materials were tested via the reduction reaction of organic pollutants such as methyl orange (MO), methylene blue (MB), and 4-nitrophenol (4-NP) as model reactions. The effects of the chemical composition of the catalyst, initial concentration of dye, catalyst mass, and chemical nature of the pollutants were assessed and discussed. To study the selectivity of the catalyst, binary systems containing MB+MO, MB+4-NP, and 4-NP+MO were evaluated. The obtained results showed that the calcination treatment promotes the formation of silver metal nanoparticles in a binary mixture, while copper and nickel are transformed into oxide forms having ultrafine sizes well dispersed in the MCM-41 framework. The ion exchange method used in this study between CTA + and the metal cation led to the deposition of low levels of metal or metal oxide on the surface of MCM-41. The catalytic tests showed good results via the reduction of MO, MB, and 4-NP, and the calculated rate constants were 0.0261, 0.0219, and 0.0107 s -1 , respectively. MCM-Ag-NiO was selected as the best catalyst based on its performance of reducing the MO dye in only 540s. In the binary systems comprising MB+MO and MB-4-NP, the MCM-Ag-NiO catalyst exhibited heightened selectivity for the MB. Conversely, within the binary system MO+4-NP, the catalyst demonstrated selectivity with MO. • Study of the catalytic performance of Ag-NiO, Ag-CuO, and NiO-CuO supported on MCM-41. • Good dispersion and ultrafine nanoparticle sizes were obtained. • Catalytic application via the reduction of MB, MO, and 4-NP in a simple binary system. • High performance and selectivity of the MCM-Ag-NiO catalyst via the MB dye.