Étude de l’intéraction nickel-oxyde de magnésium. propriétés et application de nanoparticules Ni-Mg et NiO-MgO.

Abstract

This work deals with Ni/MgO intended for use as antibacterial agents. The samples were prepared by impregnation (named NMI) followed either by irradiation under 60Co radiation (NMR) or calcined at T ≥ 100°C (NMC(T)). Various experimental techniques were used for their characterizations: UV-visible, XRD, SEM, TEM, HRTEM, SAED, FTIR, RAMAN, XPS. The structural study reveals the formation just after the impregnation step of magnesium hydroxide in addition to bimetallic Ni-Mg nanoparticles (Ni2Mg, NiMg2, Mg6.33) of size 2 to 4 nm. These phases are present both in the irradiated sample and in the samples calcined at T≤ 300°C. For T >300°C, they disappear to the detriment of a new phase NiMgO2. The study of the surface state by XPS shows that for all the samples the nickel is very dispersed and that it is in the oxidized state on the surface. MgO, Ni/MgO impregnated and impregnated and calcined samples were tested as antibacterial agents against E. coli (G-) and S. aureus (G+). This study revealed that MgO is toxic against E. coli and inactive against S. aureus. An opposite behavior is observed for NMC(400). NMC(300) has the highest toxicity against both bacteria, consistent with its large specific surface area. The antibacterial activity of these compounds is linked to Mg(OH)2 on the one hand and on the other hand to the synergistic effect of nickel and magnesium present in Ni-Mg and NiMgO2.