Removal of pharmaceutically active compounds (PhACs) and bacteria inactivation from urban wastewater effluents by UVA-LED photocatalysis with Gd3+ doped BiVO4

Abstract

In this study, gadolinium doped bismuth vanadate powders were synthesized, characterized, and tested as a potential photocatalyst for the removal of pharmaceutically active compounds (PhACs) and bacterial inactivation in a real wastewater effluent using UVA as irradiation source. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies revealed that the bismuth vanadate system was successfully doped with 4% of gadolinium in molar mass leading to the formation of a heterostructured photocatalyst. Up to 98.3 % of diclofenac was removed from pure water after 120 min through photocatalysis. However, the photocatalytic performance of the photocatalyst on wastewater effluent was rather variable due to the complexity of the matrix where 22 different PhACs were detected by means of Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS). High photocatalytic removal efficiency (80–100%) was observed for some of the studied PhACs (e.g. naproxen and furosemide) whereas moderate efficiency (40–70%) was observed for others (e.g. acetaminophen and azithromycin) after 180 min (UVA dose = 139.5 Wh m−2, t30W = 279 min-1). Some of the studied PhACs like clarithromycin and Ibuprofen showed poor removal efficiency (< 30 %). In disinfection tests, Total coliforms, Escherichia coli, Enterococci, and Klebsiella pneumoniae showed inactivation after direct UVA LED photolysis. Nevertheless, higher inactivation was achieved for Enterococci in the presence of the synthesized photocatalyst showing an increase of 41.1 % in kmax.