Chemical Engineering

The present work shows the application of the UV-vis/H 2 O 2 process, Fenton-and photo Fenton-like reactions in presence of zeolite material ZSM5 in the degradation of a pharmaceutical pollutant recently found in environmental aquatic systems, the anti-inflammatory drug naproxen (NPX). Three commercial iron oxide powders (hydrated hematite, hematite, and magnetite) for Fenton-like reaction were tested against 10 mg L À1 of NPX. An UV-vis simulator source was employed in order to contrast the performance of the photo Fenton-like reaction during 120 min of irradiated conditions in a no-buffered almost neutral pH 6.5 ± 0.5. ZSM5 zeolite was tested as adsorbed material in mechanical mixtures with or without iron oxide powders in order to improve the physical removal along with the oxidative stress. Effects of non-photocatalytic control test (such as UV-vis photolysis, H 2 O 2 oxidation, and oxide iron complex formation) were previously evaluated. Negligible effect was evidenced for Fenton-like reaction and adsorption in dark conditions by the use of neither iron oxide species nor zeolite (<0.01 mmol NPX L À1 min À1). In contrast, the photo-Fenton-like reaction promotes the total elimination of initial 10 mg L À1 of NPX with a concomitant 50-60% of mineralization by the use of Fe 2 O 3 and Fe 3 O 4 , respectively, with 18 and 14 mmol L À1 min À1 initial NPX degradation rate. Improvement of dissolved organic carbon (DOC) reduction by adsorption due to the presence of ZSM5 was not observed under illuminated conditions and biodegradable character of the final effluent was not improved. The presence of a heterogeneous material such as zeolite ZSM5, promotes only a benefit effect on DOC removal in absence of H 2 O 2 reagent and results are antagonist to Fenton-like and photo-Fenton-like reactions due to the well-differentiated reaction mechanism and the concomitant likely dissimilar by-products generated. Residual by-products are not suitable for a post-biological operation due to the formation of recalcitrant polymers not further degraded by photo-Fenton-like reaction with iron oxides.

Degradation of the biorecalcitrant pharmaceutical micropollutant ibuprofen (IBP) was carried out by means of several advanced oxidation hybrid configurations. TiO 2 photocatalysis, photo-Fenton and sonolysis-all of them under solar simulated illuminationwere tested in the hybrid systems: sonophoto-Fenton (FS), sonophotocatalysis (TS) and TiO 2 /Fe 2þ /sonolysis (TFS). In the case of the sonophoto-Fenton process, the IBP degradation (95%) and mineralization (60%) were attained with photo-Fenton (FH). The presence of ultrasonic irradiation slightly improves the iron catalytic activity. On the other hand, total removal of IBP and elimination of more than 50% of dissolved organic carbon (DOC) were observed by photocatalysis with TiO 2 in the presence of ultrasound irradiation (TS). In contrast only 26% of mineralization was observed by photocatalysis with H 2 O 2 (TH) in the absence of ultrasound irradiation. Additional results showed that, in the TFS system, 92% of DOC removal and complete degradation of IBP were obtained within 240 min of treatment. The advanced oxidation hybrid systems seems to be a promising alternative for full elimination/mineralization for the recalcitrant micro-contaminant IBP.

In this study the degradation of the worldwide Non-Steroidal Anti-Inflammatory Drug (NSAID) ibuprofen (IBP) by photo-Fenton reaction by use of solar artificial irradiation was carried out. Non-photocatalytic experiments (complex formation, photolysis and UV/Vis-H 2 O 2 oxidation) were executed to evaluate the isolated effects and additional differentiated degradation pathways of IBP. The solar photolysis cleavage of H 2 O 2 generates hydroxylated-IBP byproducts without mineralization. Fenton reaction, however promotes hydroxylation with a 10% contamination in form of a mineralization. In contrast photo-Fenton in addition promotes the decarboxylation of IBP and its total depletion is observed. In absence of H 2 O 2 a decrease of IBP was observed in the Fe(II)/UV-Vis process due to the complex formation between iron and the IBP-carboxylic moiety. The degradation pathway can be described as an interconnected and successive principal decarboxylation and hydroxylation steps. TOC depletion of 40% was observed in photo-Fenton degradation. The iron-IBP binding was the key-point of the decarboxylation pathway. Both decarboxylation and hydroxylation mechanisms, as individual or parallel process are responsible for IBP removal in Fenton and photo-Fenton systems. An increase in the biodegradability of the final effluent after photo-Fenton treatment was observed. Final BOD 5 of 25 mg L À1 was reached in contrast to the initial BOD 5 shown by the untreated IBP solution (BOD 5 < 1 mg L À1). The increase in the biodegradability of the photo-Fenton degradation byproducts opens the possibility for a complete remediation with a final post-biological treatment.

The aim of this work is to evaluate and compare the degradation achieved for three nonsteroidal anti-inflammatory drugs (NSAIDs) by heterogeneous TiO 2 photocatalytic means in aqueous solution at laboratory scale. The selected pharmaceutical compounds were diclofenac (DCF), naproxen (NPX) and ibuprofen (IBP). These compounds were used in their sodium salt chemical form. Previous experiments (adsorption, photolysis and thermodegradation) were developed to evaluate non-catalytic degradation for each NSAID. Photocatalytic experiments were carried out in a Xe-lamp reactor in order to study the influences of different operational conditions (catalyst load, temperature and dissolved oxygen concentration). These results showed that the optimum amount of TiO 2 , to achieve maximum degradation, of IBP was 1 g/L. In contrast, the maximum degradation for DCF or NPX was observed at a TiO 2 loading of 0.1 g/L. Temperature had a significant effect only for NPX degradation, achieving almost 99% phototransformation. No significant differences were observed for DCF and IBP at 20, 30 and 40 1C. Dissolved oxygen concentration was an important parameter to increase the degradation for NPX and IBP. However, it was observed that its rate of mineralization did not increase. Intermediate metabolites were detected in all cases. Hydroxyl metabolites were the most important residual compounds after the photocatalytic treatment of IBP. The inhibition percentage of bioluminescence from Vibro fischeri-as a toxicity parameterincreased during the irradiation time due to the residual concentration of the hydroxyl metabolites generated. However, after 120 min, in experiments with 40 mg/L of dissolved oxygen, a decrease of the % inhibition was observed. Only photocatalytic treatment of IBP drives to a satisfactory biodegradability index BOD 5 /COD (between 0.16 and 0.42) and, only in this case, a post-biological treatment could be suggested.

From a technical point of view, currently, one of the most important problems to be solved in solar heterogeneous photocatalytic processes is related to the impractical use of the photocatalytic material in suspension form. In this study, we propose and develop 3D-printed hierarchical structures of entirely TiO 2 consistency in order to investigate their effective photochemical and structural performance. Robocasting and deposition processes assisted the extrusion process through a syringe-type nozzle, dispensing, layer-by-layer, fine filaments of the catalytic paste and manufactured solid square-lattice double-diagonal (SLDD) structures. The concentration effect of SLDD solid pieces and nanopowder suspensions of TiO 2 were compared for acesulfame (ACE) degradation as a model pollutant. 99% and 79% removal of 20 mg/L of ACE in solution were reached in 60 min of UV-Vis irradiation by use of 0.500 and 22 g/L of TiO 2 in slurry and SLDD form, respectively. Long-term periods of use of SLDD pieces showed that the photocatalytic activity, pH and DO evolution remain unaltered after several cycles of reuse without macrostructure deformation or deterioration of the SLDD pieces. The optimal geometry of 3D printed structures of entirely TiO 2 composition with optimum photonic flow distribution in solar reactors is a promising assignment to be achieved for the incoming commercial use of photocatalytic technologies at large scale for environmental sustainable applications.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) has been widely used as organic arsenic additive in animal industry. In this study, the adsorption of roxarsone on TiO 2 under dark conditions, the photocatalytic decomposition of roxarsone under UV/TiO 2 , and the possible photocatalytic pathway were investigated. At the initial concentration of 5-35 mg/L, the adsorption of roxarsone fitted well with the pseudo-second-order kinetics. The isotherms analysis showed that the Langmuir model was better than the Freundlich and Dubinin-Radushkevich models for describing the adsorption process. After 7 h of photocatalytic decomposition, a complete disappearance of roxarsone was achieved. The pH value has a significant effect on both adsorption and photocatalytic decomposition of roxarsone. The results of high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) and gas chromatography-mass spectrometry (GC/MS) analyses proved the cleavage of the As-C bond during the photocatalytic decomposition process by TiO 2 and the intermediates of the decomposition. Based on the results, a possible photocatalytic decomposition pathway was proposed.

The aim of this study was to investigate and compare the effect of an advanced oxidation process, the photocatalysis, on the removal of two emerging contaminants in water; the pharmaceuticals metoprolol tartrate salt (MET) and propranolol hydrochloride (PRO). The analyzed parameters were pharmaceutical removal, total organic carbon (TOC), specific UV absorbance (SUVA), chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ), toxicity and formed intermediates. Besides, the optimal photocatalyst concentration was determined. Afterwards, photocatalytic experiments were carried out with 0.4 g L −1 of TiO 2 as suspended catalyst and a Xenon lamp (Philips XOP 15-OF, 1000 W) as irradiation source. According to the results, after 240 min of irradiation, a removal near to 94% was obtained for both compounds. After 360 min of treatment, a mineralization degree in the vicinity of 55% was observed. Biodegradability index (BOD 5 /COD) improved from values close to zero (raw solution) up to 0.4 and 0.6 for MET and PRO. The acute toxicity measured by the inhibition percentage of bioluminescence from Vibro fischeri indicates that the photocatalytic treatment of this kind of compounds promotes toxicity reduction. According to the experimental results, photocatalysis appears as a useful technique for the degradation of both ␤-blockers.