Fast and Efficient Piezo-Photocatalytic Mineralization of Ibuprofen by BiOBr Nanosheets under Solar Light Irradiation

In the present work, the piezoelectric-like behavior of BiOBr nanosheets was utilized to suppress the recombination of photoexcited charges. The piezo-photocatalytic properties of an easily synthesized photocatalyst were tested for the degradation of ibuprofen, a nonsteroidal anti-inflammatory drug. Under ultrasound and solar light irradiation, the reaction rate for ibuprofen mineralization was found to be higher in the BiOBr nanosheets compared with those from the individual photocatalysis and piezocatalysis approaches, respectively. A percentage of synergy higher than 60% was calculated, resulting in the achievement of complete mineralization in less than 30 min. Based on the results, a possible piezo-photocatalytic mechanism, based on the separation of photoinduced charges and the formation of highly active radicals, has been proposed. Furthermore, various scavengers were used to identify the active species by trapping holes and radicals generated during the piezo-photocatalytic degradation process. The main transformation products formed during both photo- and piezo-photodegradation processes were identified by ultraperformance liquid chromatography-mass spectrometry (UPLC/MS), and the ibuprofen degradation pathway was proposed. The very promising results offer an advantageous approach to drug mineralization without the need for costly materials or expensive processes.