Photocatalytic decomposition of pharmaceutical ibuprofen pollutions in water over titania catalyst

Due to the growing importance of low concentrated pollution of surface, ground and drinking, the photocatalytic decomposition of ibuprofen down to low ppm concentrations over titania catalyst has been investigated in detail. The catalyst was characterized by XRD, TEM, diffuse reflection UV–Vis and nitrogen adsorption measurement. The photocatalytic abatement of ibuprofen was monitored by UV–Vis spectrometry, chromatographic by GC/MS, and HPLC coupled electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). Catalytic performance has been studied by varying the catalyst and substrate concentration as well as decreasing the catalyst-to-substrate mass ratio over a wide range. The photocatalytic treatment with titania catalyst leads to rapid mineralization of ibuprofen. Formation of intermediate reaction products has been investigated. It is proposed that intermediates in part form oligomeric species, which are responsible for catalyst poisoning. Additional, the influence of the pH value, oxygen supply and catalyst re-use have been checked.

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► The photocatalytic decomposition of ibuprofen over TiO2 was studied at low concentration.
► IBP and catalyst concentration and catalyst-to-substrate ratio were varied over a wide range.
► Rapid depollution under UV–Vis light is accompanied by formation of temporary by-products.
► ESI-TOF-MS analysis points to the formation of recalcitrant oligomeric intermediates.
► Re-use experiments show catalyst poisoning and increase of reaction intermediates.