Abstract:
Heterogeneous photocatalysis using titanium dioxide (TiO2) and zinc oxide (ZnO) has
been widely studied in various applications, including organic pollutant remediation in aqueous
systems. The popularity of these materials is based on their high photocatalytic activity, strong
photosensitivity, and relatively low cost. However, their commercial application has been limited by
their wide bandgaps, inability to absorb visible light, fast electron/hole recombination, and limited
recyclability since the nanomaterial is difficult to recover. Researchers have developed several strategies
to overcome these limitations. Chief amongst these is the coupling of different semi-conductor
materials to produce heterojunction nanocomposite materials, which are both visible-light-active
and easily recoverable. This review focuses on the advances made in the development of magnetic
ferrite-based titanium oxide and zinc oxide nanocomposites. The physical and magnetic properties of
the most widely used ferrite compounds are discussed. The spinel structured material had superior
catalytic and magnetic performance when coupled to TiO2 and ZnO. An assessment of the range of
synthesis methods is also presented. A comprehensive review of the photocatalytic degradation of
various priority organic pollutants using the ferrite-based nanocomposites revealed that degradation
efficiency and magnetic recovery potential are dependent on factors such as the chemical composition
of the heterojunction material, synthesis method, irradiation source, and structure of pollutant. It
should be noted that very few studies have gone beyond the degradation efficiency studies. Very
little information is available on the extent of mineralization and the subsequent formation of intermediate
compounds when these composite catalysts are used. Additionally, potential degradation
mechanisms have not been adequately reported.
