Zinc Oxide/Iron Oxide Nanocomposites for Photodegradation and Adsorption of Pollutants in Water

The presence of different pollutants in water bodies has increased over the years with population and industrial activity growth. This phenomenon produces a deterioration in water quality. In this context, improved, low-cost, and green strategies to remediate water from different sources are currently mandatory. This paper deals with the evaluation of three synthetic pathways to obtain nanocomposites (NCs) based on zinc oxide (Z) and iron oxide (M) nanoparticles. An exhaustive characterization was performed on the three NCs achieved. X-ray diffraction and Fourier transform infrared data determined that synthetic method 3 did not lead to NC formation. The synthetic pathways determined the NC structure, as is demonstrated by the transmission electron microscopy and scanning electron microscopy data from MZ1 and MZ2, respectively. Eg values between 2.3 and 2.9 eV were achieved, suggesting the formation of a heterojunction structure. Superparamagnetic behavior was confirmed for MZ1 and MZ2, giving magnetizations of saturation of 51.3 and 64.0 emu/gFe, respectively. Because the aim was to design materials able to function by dual adsorption–photodegradation mechanisms, their performance was evaluated from batch assays using ammonium as a model of an inorganic pollutant and methylene blue (MB) as an organic one. The adsorption of ammonium was effective and reached efficiencies of 48.5% for MZ1 and 53.1% for MZ2. The maximum efficiency in MB photodegradation (98%) was reached using MZ2. Antibacterial properties were also assayed, finding satisfactory responses against Escherichia coli and Bacillus thuringiensis for both NCs. The data collected within this work positioned MZ materials as suitable tools to remediate sewage, which mostly contains the group of pollutants evaluated in this paper.