About a Novel Production Method for N-Doped Magnetic Nanocore Nanoparticles of Titania by Means of a Spinning Disk Reactor

This study reports a novel approach to produce nitrogen doped magnetic core TiO2 nanoparticles (NTiO2/FM). The treatment of wastewater streams by photocatalysis appears a feasible pre-treatment for many subsequent purification steps, such as membranes. In order to keep high efficiencies in dealing with the wastewater streams, the photocatalyst requires to be suspended in order to reach the water surface for proper irradiation and operation. A main drawback is the recovery of the suspended photocatalyst, that may be accomplished by magnetic filters (up to 99.9%) as soon as the titania nanoparticles are attached to magnetic nanocores (FM). Moreover, the photocatalyst should react to visible light and not only to UV (as pure titania), to operate with a high energy efficient process that may use LED lamps instead of UV lamps. This property can be acquired through nitrogen doping. Therefore, the production of NMTNP may represent a general solution to all these problems. The N-TiO2/FM were synthesised starting with the production of magnetic nanocores by SDR and their coating of silica by using the Stroeber method. Finally, FM particles were dispersed in Urea solution and then titanium tetraisopropoxide (TTIP) is added to produce N-TiO2/FM, respectively. In the final stage of production, the N-TiO2/FM solution is washed and calcinated at higher temperatures. The final product is a core-shell-shell nanoparticle of FM/silica and titania. The experimental runs performed in an aerated photoreactor for phenol degradation shows the efficiency of NMTNP for purification purposes and its easily recovery by magnets.