Effects of niobium and molybdenum impregnation on adsorption capacity and Fenton catalytic activity of magnetite

Abstract

In the present study, a number of modified magnetite samples were prepared by impregnating magnetite with Nb and Mo (Fe_3−x−yNb_xMo_yO₄, x + y = 0.2). The characteristics of the samples in terms of durability, crystalline phase, morphology, size, surface area and composition, and magnetic property were determined. Subsequently, the effect of Nb and Mo incorporation on adsorption capacity of magnetite and its activity in heterogeneous Fenton oxidation of methylene blue was investigated. The amount of MB adsorbed on the synthesized samples increased considerably, mainly due to the increase in their specific surface area. In addition, the presence of Nb and Mo significantly improved degradation of MB, especially at higher contents of Nb + Mo. About 90% of MB (100 mg L⁻¹) and 46% of TOC were removed under the studied conditions. MB adsorption and Fenton degradation using synthesized samples were well described by pseudo-second-order and pseudo-first-order equations in kinetics, respectively. The samples demonstrated good durability and insignificant loss of performance in three consecutive experiments. The obtained results verified that Nb and Mo co-incorporation could effectively improve magnetite properties towards higher adsorption and remarkable activity in heterogeneous Fenton process at neutral condition.