Fe3O4/TiO2:Eu composite nanoparticles for photocatalytic water purification
Authors: Maria Ștefan, Dana Toloman, Adriana Paula Popa, Ioan Ovidiu Pană
Keywords: composite nanoparticles, depollution, photocatalytic effect
Applications
Consumption of contaminated water containing organic contaminants, pathogenic microbes, and heavy metals has been linked to public health problems.
The photocatalytic effect, which is an alternative form of wastewater treatment, can degrade organic contaminants into CO2 and H2O.
Innovative aspects
To achieve large-scale wastewater depollution using photocatalysis, a reusable material that possesses enhanced photocatalytic capabilities, visible response, and ease of separation from the aqueous medium needs to be developed.
Doping with transient ions or rare earths increases photocatalytic activity. Thus, doping with Eu3+ ions promotes the transfer of excitonic electrons to the surface of TiO2 nanocrystallites, where they generate reactive oxygen species, which function as strong oxidizing agents, resulting in the degradation of organic contaminants.
To quickly extract the photocatalyst from the aqueous solution, it requires to be coupled with a magnetic substance that allows it to be easily manipulated using an external magnetic field.
Our group’s technological strategy is as follows: we combined the semiconductor (TiO2:Eu) and magnetite (Fe3O4) by optimizing the concentration of doped Eu3+ ions as well as the TiO2 to Fe3O4 ratio to obtain an efficient photocatalytic process.
Technology
Fe3O4 nanoparticles were obtained by the co-precipitation method starting from a mixture of iron chlorides in a basic medium. The Fe3O4/TiO2:Eu nanocomposite was realized by the seeding method in such a way that the growth of TiO2 crystallites occurs on the surface of magnetite nanoparticles.
Titanium dioxide was actually prepared using the sol-gel process. The resulting TiO2 nanoparticles have an average size of 20 nm.
The formation of the composite can be easily confirmed by X-ray diffraction. The photocatalytic activity of the obtained composite nanoparticles was evaluated by visible light irradiation in the presence of Rhodamine B synthetic solution.
Advantages
- The small size of the nanoparticles ensures a large contact surface with the pollutant molecules
- Composite nanoparticles absorb light in the visible range, with a maximum at 670 nm
- Composite nanoparticles preserve magnetite’s ferromagnetic property, therefore their separation from aqueous solutions can be easily performed using a magnet
- Preparation and separation technology do not require sophisticated infrastructure and can often be done at limited production costs