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The photocatalytic degradation in distilled water of 15 selected emerging contaminants (ECs) has been evaluated in a solar pilot compound parabolic collector (CPC) plant by using TiO2 photocatalysts immobilized on glass spheres. The durability of the photocatalysts has been evaluated by measuring its performance during 4 consecutive cycles. TiO2 was prepared by the sol–gel method using titanium isopropoxide as precursor, combined with commercial TiO2 Degussa P25 and polyethylene glycol (PEG) as the pore generating agent. The following microcontaminants in a concentration of 100 μg L−1 have been studied: acetaminophen, antipyrine, atrazine, carbamazepine, diclofenac, flumequine, hydroxybiphenyl, ibuprofen, isoproturon, ketorolac, ofloxacin, progesterone, sulfamethoxazole and triclosan. The fluorine containing ECs, this is, flumequine and ofloxacin, are totally degraded under the studied reaction conditions. By contrary, a progressive decay of the photocatalytic activity is observed for the other contaminants. The contaminants with amine or amide groups but without halogen heteroatoms in the structure record the lowest degradation rates. In order to recover the photoactivity, different strategies using aqueous solutions containing H2O2 under UV irradiation, NaOH, NH4OH and direct heat treatment in air at 400 °C, were adopted. For the sake of simplicity, these experiments have been performed in a solar simulator at 765 W m−2. In order to determinate the nature of the species adsorbed on the titania active sites, the used and the regenerated photocatalysts were analyzed by XPS. Chemical treatment with NaOH results in the removal of the TiO2 layer. The ECs containing sulphate, fluoride or chloride groups are easily adsorbed on the photocatalyst active sites as compared to the ECs containing amide or amine groups and are easily desorbed by the regeneration treatments. Amongst the different pretreatment studied, calcination and H2O2/UV irradiation are the most efficient methods to recover the photocatalytic activity.

This article reports on degradation using TiO2 immobilized on glass spheres of 15 emerging contaminants (ECs) at low concentrations in simulated and real Municipal Wastewater Treatment Plant (MWTP) effluents. A sol containing titanium isopropoxide, commercial P25 and polyethylene glycol (PEG) was prepared, and a layer of the photoactive precursor was immobilized on glass spheres by dip-coating. The raw materials and the xerogels were characterized by N2 adsorption/desorption, XRD and TGA-DTA. The xerogel showed the TiO2 anatase, rutile and brookite crystal phases characteristic of the reference materials. The diffraction pattern showed no modification of the crystal size from incorporation of the PEG. Two different TiO2 anatase crystal sizes were identified, which was attributed to the different TiO2 precursors used in the synthesis route. Degradation of the emerging contaminants (acetaminophen, antipyrine, atrazine, carbamazepine, diclofenac, flumequine, hydroxybiphenyl, ibuprofen, isoproturon, ketorolac, ofloxacin, progesterone, sulfamethoxazole and triclosan), at an initial concentration of 100 μg L−1 each was determined by ultra-performance liquid chromatography (UPLC-UV) and mineralization was monitored by measuring the dissolved organic carbon (DOC). The experiments were performed in a pilot compound parabolic collector (CPC) solar plant at the Plataforma Solar of Almeria (Spain). 85% of the compounds were degraded within 120 min of illumination time depending on the water. The results show the potential application of this technology as a good alternative to suspension systems for the treatment of polluted water.

The purpose of this study was to develop a municipal wastewater treatment method based on a solar advanced oxidation process (AOP) permitting reuse of the treated wastewater. The photoactive layer of TiO 2 was deposited on glass spheres using the sol–gel dip-coating technique. The film was characterized by X-ray diffraction and scanning electron microscopy (SEM). Degradation of 15 emerging contaminants (ECs), each with an initial concentration of 100 μg L −1 was determined by ultra-performance liquid chromatography (UPLC–UV) and mineralization was monitored by measuring the dissolved organic carbon (DOC). The experiments were performed in a pilot compound parabolic collector (CPC) solar plant at the Plataforma Solar of Almeria. Five cycles of photocatalysis were studied for photocatalyst durability and activity. It was demonstrated that after five cycles, although photoactivity of the catalyst slowly decreases, it continues degrading contaminants.