TiO_2 films on CoFe_2O_4 nanoparticles for the Photocatalytic oxidation of Rhodamine B: Influence of the alcoholic solutions

摘要

In the present work, photocatalytic oxidation of Rhodamine B solutions were performed using a composite materialprepared by titanium dioxide films deposited onto cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were preparedby coprecipitation of Co(Ⅱ) and Fe(Ⅱ) ions in basic medium, followed by a controlled oxidation process carried out bynitrate ions in basic medium in inert atmosphere at 95°C. The effect of 2 alcohols (ethanol and 2-propanol) as solvents inthe deposition of TiO2 films was studied as a function of CoFe_2O_4/TiO_2 mass ratios. Cobalt ferrite nanoparticles exhibited(36 ± 20) nm diameter with spheroidal shapes as confirmed by SEM studies. TiO_2 films deposited onto CoFe_2O_4 werethicker using ethanol as solvent according to SEM and TEM studies. Cobalt ferrite nanoparticles exhibit a weak oxidationbehaviour since around 40% of Rhodamine is eliminated after 90 min of exposition. The 4 composite materials studiedoxidize 100% of Rhodamine B after 60 min of reaction and kinetics results fitted a second order degradation reactionequation. As Rhodamine B solution pH was 5.83, faster reactions occur when composite materials develop low surfacecharge (PZC closer to 5.83) due to small surface charge repulsion. Materials prepared with CoFe_2O_4/TiO_2 ratios between4 to 6 present higher kinetic constants which is confirmed by a faster Rhodamine B degradation