Titania-coated nanosilica–cobalt ferrite composites: Structure and photocatalytic activity

•Novel magnetically operated effective TiO2-photocatalysts have been synthesized.•Nanosilica particles reduce the average size of cobalt ferrite particles.•Textural properties and morphology are characterized by distinct dependencies upon the content.•Synthesized nanocomposites are more active than commercial TiO2 (P25, Evonik).•Effectiveness of novel photocatalysts is proven on the practical level — in tap water.

In this study, a set of CoFe2O4/SiO2/TiO2 nanocomposites was synthesized. The total concentration of metals (Co + Fe) was varied from 3 to 9 mmol with respect to 1 g of SiO2. Titania was formed in two concentrations — 2 and 4 mmol/g. The structure of the samples was analyzed by application of XRD, UV–vis spectroscopy, magnetometry, SEM, low-temperature nitrogen adsorption–desorption and Mössbauer spectroscopy. Photocatalytic degradation of an organic model compound – carbamazepine (CBZ) – was studied in the presence of the nanocomposites under ultraviolet irradiation (λ = 254 nm) in a batch reactor. Two types of media (distilled and tap water) were used. The X-ray diffraction patterns demonstrate the formation of CoFe2O4 and TiO2 (anatase). The studied materials reveal a better activity than commercial sample of P25 (Evonik) during degradation of carbamazepine (CBZ). It has been found that the type of water medium affects the CBZ decomposition differently: there is residual CBZ observed in distilled water in 60 min of treatment. Contrastingly, in tap water the total decomposition of CBZ took place. This may be due to the occurrence of Fe3+ ions which stimulate the formation of active sites of chlorine dissolved in tap water.

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