An overview on the advanced oxidation processes applied for the treatment of water pollutants defined in the recently launched Directive 2013/39/EU.

Heterogeneous photocatalytic degradation of ibuprofen in ultrapure water, municipal and pharmaceutical industry wastewaters using a TiO2/UV-LED system

Heterogeneous activation of peroxymonosulfate by LaFeO3 for diclofenac degradation: DFT-assisted mechanistic study and degradation pathways

Degradation and mineralization of ibuprofen (IBU) were investigated using Ultraviolet (UV) Light Emitting Diodes (LEDs) in TiO 2 photocatalysis. Samples of ultrapure water (UP) and a secondary treated effluent of a municipal wastewater treatment plant (WWTP), both spiked with IBU, as well as a highly concentrated IBU (230 mg L −1 ) pharmaceutical industry wastewater (PIWW), were tested in the TiO 2 /UV-LED system. Three operating parameters, namely, pH, catalyst load and number of LEDs were optimized. The process efficiency was evaluated in terms of IBU removal using high performance liquid chromatography (HPLC) and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Additionally, the mineralization was investigated by determining the dissolved organic carbon (DOC) content. The chemical structures of transformation products were proposed based on the data obtained using liquid chromatography with a high resolution mass spectrometer ion trap/time-of-flight (LC-MS-IT-TOF). A possible pathway of IBU degradation was accordingly suggested. Bioassays were performed using the marine bacterium Vibrio fischeri to evaluate the potential acute toxicity of original and treated wastewaters. TiO 2 heterogeneous photocatalysis was efficient to remove IBU from UP and from PIWW, and less efficient in treating the wastewater from the municipal WWTP. The acute toxicity decreased by ca. 40% after treatment, regardless of the studied matrix.

Heterogeneous Photocatalytic Degradation of Ibuprofen in Ultrapure Water, Municipal and Pharmaceutical Industry Wastewaters Using a TiO2/UV-LED System

Potential risks from UV/H2O2 oxidation and UV photocatalysis: A review of toxic, assimilable, and sensory-unpleasant transformation products

Liquid chromatography time-of-flight mass spectrometry (UPLC/ESI–QToF–MS) was used for the elucidation of the main transformation products (TPs) resulting from the degradation of diclofenac (DCF) and ibuprofen (IBP) during the application of various advanced oxidation processes in aqueous matrices. The examined processes were TiO2 photocatalysis driven by UV-A or simulated solar irradiation, sonolysis, and UV-A photocatalysis integrated with ultrasound irradiation (sonophotocatalysis). A comparison between the applied treatment processes was performed with respect to the substrates first-order kinetic rate constant. When compared with sonolysis and UV-A photocatalysis, a higher degradation rate was observed for sonophotocatalysis in the presence of 500 mg L−1 TiO2. Seven TPs of IBP and ten TPs of DCF under UV-A and simulated solar irradiation photocatalysis and sonophotocatalysis, formed by consecutive attack of hydroxyl radicals (HO•) in concomitance with the degradation of the primary compounds, were tentatively identified. Overall, no differences were observed in the nature of TPs formed for each substrate among the experiments performed, indicating the involvement of similar reaction mechanisms. The degradation pathway of IBP includes mainly decarboxylation, demethylation and hydroxylation reactions, while the oxidation of DCF, mainly proceeded by oxidation and hydroxylation reactions between chloroaniline and phenylacetic acid. An important observation made during the experiments was that the hydroxylated species (1′-OH-IBP; 2′-OH-IBP; 4′-OH-DCF; 5′-OH-DCF) remained in the solution until 120 min. Finally, the results demonstrated the capacity of the sonophotocatalysis to reduce the initial toxicity of IBP and DCF aqueous solutions against the water flea Daphnia magna yielding 20% and 40% immobilization, respectively, at the end of the treatment.

V. Osorio Torrens

Papers

Proposed transformation pathway and evolution profile of diclofenac and ibuprofen transformation products during (sono)photocatalysis