Enhanced activity and reusability of TiO2 loaded magnetic activated carbon for solar photocatalytic ozonation

• Optimized synthesis procedure of TiO2-coated magnetic activated carbon catalysts.
• The catalysts are highly active and stable upon photocatalytic ozonation of metoprolol.
• After 50 h reused catalyst led to the complete conversion of metoprolol and 80% mineralization.
• Simplified multi-step reaction pathway is proposed for photocatalytic ozonation process.

Magnetically separable photocatalysts with high activity under solar illumination were successfully synthesized from a commercial meso-to-microporous activated carbon. First magnetite and then titania (anatase) were deposited onto the activated carbon support by impregnation and sol–gel methods, respectively. Various catalyst samples were prepared with different iron and titania contents. The synthesized photocatalysts were characterized by nitrogen adsorption, XRD, SEM, EDX, XPS and SQUID magnetometer. Photocatalytic performance of some selected samples was examined under various irradiation conditions in the wavelength ranges of 300–800 nm, 320–800 nm and 390–800 nm. Metoprolol tartrate (MTP) in aqueous solution (50 mg L−1) was chosen as target compound for catalytic activity tests. The most efficient catalyst had TiO2 and Fe mass compositions of 64 wt% and 9 wt%, respectively. It showed high activity in photocatalytic ozonation with complete removal of MTP in less than 2 h reaction time and 85% mineralization after 5 h. This catalyst was also easily separable due to its developed magnetic properties. Catalyst reusability and stability was proved to be rather good after completing a series of 10 consecutive photocatalytic ozonation runs.

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