Surface interactions and degradation of a fluoroquinolone antibiotic in the dark in aqueous TiO2 suspensions

Abstract

Fluoroquinolone antibiotics (FQs) are important drugs used in human and veterinary medicine. Their detection in natural waters and waste water treatment plants, along with increased resistance to FQs among some bacteria, have generated an increased interest in the fate of these drugs in the environment. Partitioning of FQs between an aqueous solution and attendant substrates depends, in part, on the surface reactivity of the adsorbent, commonly a function of particle size, surface charge, and functional groups. This study investigated the surface interactions between the FQ drug ofloxacin (OFL) and titanium oxide (TiO2), a common catalyst and widely-observed constituent in many consumer products. Raman and fluorescence spectroscopic techniques, as well as LC/MS, were used to determine the OFL moieties present on TiO2 surfaces and in attendant solutions. Raman spectra indicate that the CO (ketone) group of the quinolone core, the NH(+) of the piperazinyl ring, and CH3 of benzoxazine core are the most active in sorption onto the TiO2 surface. Raman spectra also show that the sorbed benzoxazine-quinolone core and piperazinyl moieties are readily desorbed from the surface by re-suspending samples in water. Importantly, we found that OFL could be degraded by reacting with TiO2 even in the dark. Complementary LC/MS analysis of the attendant supernatants indicates the presence of de-piperazinylated and de-carboxylated OFL breakdown products in supernatant solutions. Together, both Raman and LC/MS analyses indicate that TiO2 breaks the compound into piperazinyl and carboxylate groups which attach to the surface, whereas de-carboxylated and hydroxylated quinolone moieties remain in solution. The present study thus identifies the sorption mechanisms and breakdown products of OFL during dark reactions with TiO2, which is critically important for understanding the fate and transport of OFL as it enters the soil and aquatic environment.

Superior photocatalytic properties of carbonized PANI/TiO2 nanocomposites

“…Also, during the carbonization process, the oxygen containing species (carboxyl group, ketone, quinone, phenol, pyrene ether, and pyridine oxide) could be created on the surface of carbonized PANI, Fig. 1d, [15][16][17][18][19][20][21][22]53,54] opening the possibility for more efficient interaction with TiO2 NPs [55][56][57]. Moreover, Li and coworkers find a possibility for Ti-O-N and Ti-O-C interactions between TiO2 NPs and N and O atoms in carbonized structures [58].…”

Adsorptive Removal of Fluoroquinolones from Water by Pectin-Functionalized Magnetic Nanoparticles: Process Optimization Using a Spectrofluorimetric Assay

“…Drugs used in both human and veterinary medicine have been detected in surface water and groundwater in concentrations ranging from ng/L to mg/L . Among these drugs are antibiotics and their metabolites which can reach the environment through different ways, such as pharmaceutical manufacturing plants effluents, human or animal wastes, hospital wastewater, and municipal wastewater treatment plants .…”

Enhanced visible-light-induced photocatalytic activity of anatase TiO2 nanocrystallite derived from CMK-3 and tetrakis(dimethylamino)titanium

“…For TiO 2 -600, the reection peaks at 25.3, 37.8, 48.04, 53.9, 55.1, 62.7, 68.8, 75.2 corresponded to the planes of (101), ( 004), ( 200), ( 105), ( 211), ( 204), ( 116), ( 220), (215), respectively, which can be well indexed to the tetragonalanatase crystal phase (JCPDS No. 84-1285), 14,[35][36][37][38] indicating that the prepared TiO 2 -600 mainly consists of anatase crystal structure. Nevertheless, unassigned peaks can be observed at approximately 14.5 and 33.3 , which are most likely attributed to TiO 2Àx , and can be further proved to be oxygen defects by the XPS and EPR measurements, indicating that the oxygen defects were produced during the annealing procedure.…”