TiO2-modified zeolites for fluoroquinolones removal from wastewaters and reuse after solar light regeneration

• TiO2-modified zeolites are efficient for removing fluoroquinolones from wastewaters.
• Solid-state photodegradation of sorbed FQs is investigated for the first time.
• TiO2 coating increases the photodegradation rate of sorbed pollutants.
• The photodegradation is effective under natural solar light.
• The materials can be recycled with no loss of efficiency.

Adsorption and photocatalytic removal from water of marbofloxacin (MAR) and enrofloxacin (ENR), two fluoroquinolone (FQ) antibiotics widely present in surface waters, were investigated on zeolite Y derivatized with three different TiO2 catalysts (P25 Degussa and TiO2 obtained by optimization of a sol–gel method). The prepared materials were characterized by X-rays powder diffraction (XRPD), scanning electron microscopy (SEM), BET analysis and diffuse reflectance spectroscopy (DRS). TiO2-derivatization improved the adsorption capacities of zeolite Y for FQs and promoted the sunlight-induced degradation of FQs adsorbed (solid-state photodegradation), not investigated in literature yet. A large FQs removal (3 mg g−1) occurred in about 2 h (residual adsorbed FQs < 0.03%). The degradation curves of FQs and the evolution profiles of the photoproducts were monitored, after microwave-assisted extraction, by high-performance liquid chromatography coupled to UV detection (HPLC-UV), thus proving the effectiveness of solar radiation in the photocatalytic removal of the drugs adsorbed on TiO2-modified zeolites, that can be recycled for further adsorption/photodegradation cycles, with no loss of sorption capability and photocatalytic activity. A complete removal of FQs from the outlet of a wastewater treatment plant samples, spiked with MAR and ENR at the micrograms per litre levels, was obtained with the best performing modified zeolite.

Figure optionsDownload as PowerPoint slide