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Obesity causes systemic inflammation, hepatic and renal damage, as well as gut microbiota dysbiosis. Alternative vegetable sources rich in polyphenols are known to prevent or delay the progression of metabolic abnormalities during obesity. Vachellia farnesiana (VF) is a potent source of polyphenols with antioxidant and anti-inflammatory activities with potential anti-obesity effects. We performed an in vivo preventive or an interventional experimental study in mice and in vitro experiments with different cell types. In the preventive study, male C57BL/6 mice were fed with a Control diet, a high-fat diet, or a high-fat diet containing either 0.1% methyl gallate, 10% powdered VFP, or 0.5%, 1%, or 2% of a polyphenolic extract (PE) derived from VFP (Vachellia farnesiana pods) for 14 weeks. In the intervention study, two groups of mice were fed for 14 weeks with a high-fat diet and then one switched to a high-fat diet with 10% powdered VFP for ten additional weeks. In the in vitro studies, we evaluated the effect of a VFPE (Vachellia farnesiana polyphenolic extract) on glucose-stimulated insulin secretion in INS-1E cells or of naringenin or methyl gallate on mitochondrial activity in primary hepatocytes and C2C12 myotubes. VFP or a VFPE increased whole-body energy expenditure and mitochondrial activity in skeletal muscle; prevented insulin resistance, hepatic steatosis, and kidney damage; exerted immunomodulatory effects; and reshaped fecal gut microbiota composition in mice fed a high-fat diet. VFPE decreased insulin secretion in INS-1E cells, and its isolated compounds naringenin and methyl gallate increased mitochondrial activity in primary hepatocytes and C2C12 myotubes. In conclusion VFP or a VFPE prevented systemic inflammation, insulin resistance, and hepatic and renal damage in mice fed a high-fat diet associated with increased energy expenditure, improved mitochondrial function, and reduction in insulin secretion.

In this research work, boron-doped titanium oxide (B-TiO2) was prepared by the sol-gel method to investigate its behavior in the degradation of the recalcitrant hormone estriol (E3). The doped photocatalyst was synthesized at different boron/titania ratios of 2, 3, and 5 wt.% of boron with respect to the TiO2 content. The obtained materials were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The textural properties, specific surface area, and porosity were obtained from N2 adsorption–desorption isotherms by BET and BJH methods, respectively. The photocatalytic performance of each synthesized catalyst was evaluated on the degradation of an aqueous solution (10 mg/L) of estriol (E3) under simulated solar radiation. The variation in the hormone concentration was determined by the HPLC technique, and the mineralization was evaluated by the quantification of total organic carbon (TOC). The obtained results indicated that the catalyst with 3 wt.% of boron incorporation exhibited the best performance on the degradation and mineralization of estriol, achieving its complete degradation at 300 kJ/m2 of accumulated energy and 71% of mineralization at 400 kJ/m2 (2 h) obtaining a non-toxic effluent.

A new synthesis method to prepare the heterostructured catalyst MIL-101(Fe) derived Fe2O3 with TiO2 via microwave-assisted sol-gel route followed by pyrolysis was carried out. The mixed oxide catalyst was characterized by high-resolution transmission electron (HRTEM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis DRS spectroscopy, N2 physisorption, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), photoluminescence (PL), and zetametry. The photocatalytic activity was evaluated in the degradation of the nonsteroidal anti-inflammatory drugs (NSAIDs), ibuprofen (IBP), and naproxen (NPX) in a mixture (10 mg/L/each one) at pH 3, using 1 g/L of the catalyst under visible light. The synthesized Fe2O3/TiO2 showed higher surface area, smaller average crystallite size, absorption in the visible range, and narrower band gap than TiO2, which enhanced the photocatalytic performance of TiO2 under visible radiation, allowing 91 and 100% degradation of IBP and NPX within 240 and 15 min of reaction, respectively. Moreover, 79.0% of mineralization of the mixture of NSAIDs in 240 min was achieved using the derived Fe2O3/TiO2 showing good reusability and stability even after three cycles of usage. In the photocatalytic process, holes were the dominant species for NSAIDs degradation.

An automated methodology (SPE-HPLC-UV) is proposed in this work for the determination of plasticisers in water samples collected at different stages of two wastewater treatment plants (WWTPs). Bisphenol A (BPA) and 4-tert-butylphenol (4tBP) were chosen as model pollutants. The 33−1 fractional factorial experimental design (FFED) was used to determine more significant variables associated with the preconcentration procedure. The factors studied were the adsorbent composing the SPE membrane disk, sample volume and pH of the sample. Three SPE membranes disks were evaluated: (1) C18 octadecyl bonded silica (C18), (2) styrenedivinylbenzene‐extra clean (SDB‐XC) copolymer, and (3) styrenedivinylbenzene‐reversed-phase sulphonated (SDB‐RPS) copolymer. The preconcentration conditions selected were the SDB-RPS membrane disk as the sorbent, a sample volume of 30 mL and a solution pH of 7. HPLC-UV analysis was achieved isocratically using a C18 column with CH3CN:H2O, 60:40% v v−1, at a flow rate of 1.0 mL min−1. The linearity range was between 5 and 80 μg L−1 with determination coefficients (R2) higher than 0.9989. The limits of detection (LODs) were 0.77 and 1.46 μg L−1 for BPA and 4tBP, respectively. Furthermore, the intraday and interday precisions expressed in terms of relative standard deviation (RSD) were found between 2.5–5.0% and 4.6–6.0%, respectively. Excellent recovery rates (72.2–99.8%) were demonstrated by spiking known concentrations of BPA and 4tBP in the WWTP samples. The proposed methodology was successfully applied to determine BPA and 4tBP in water samples of two WWTPs from the metropolitan area of Monterrey, Mexico. BPA was found in wastewater influent ranging from 5.9 to 16.6 μg L−1, while 4tBP was detected in samples from different stages of WWTPs in concentrations ranging from 4.9 to 21.5 μg L−1.

The novel [Cuphen(VBA)2H2O] complex (phen: phenanthroline, VBA: vinylbenzoate) was prepared and used as a functional monomer to preorganize a new ion-imprinted polymer (IIP). By leaching the Cu(II) from the molecular imprinted polymer (MIP), [Cuphen(VBA)2H2O-co-EGDMA]n (EGDMA: ethylene glycol dimethacrylate), the IIP was obtained. A non-ion-imprinted polymer (NIIP) was also prepared. The crystal structure of the complex and some physicochemical, spectrophotometric techniques were also used for the MIP, IIP, and NIIP characterization. The results showed that the materials are nonsoluble in water and polar solvents, which are the main features of polymers. The surface area of the IIP is higher than the NIIP demonstrated by the blue methylene method. The SEM images show monoliths and particles smoothly packed together on spherical and prismatic-spherical surfaces in the morphology of MIP and IIP, respectively. Moreover, the MIP and IIP could be considered as mesoporous and microporous materials, shown by the size of the pores determined by the BET and BJH methods. Furthermore, the adsorption performance of the IIP was studied using copper(II) as a contaminant heavy metal. The maximum adsorption capacity of IIP was 287.45 mg/g at 1600 mg/L Cu2+ ions with 0.1 g of IIP at room temperature. The Freundlich model was found to best describe the equilibrium isotherm of the adsorption process. The competitive results indicate that the stability of the Cu-IIP complex is higher than the Ni-IIP complex with a selectivity coefficient of 1.61.

Porous carbon derived from amine-functionalized MIL-125 metal-organic framework (C-MIL-125-NH2) was prepared by carbonization at high temperature under inert atmosphere, and used for adsorption of bisphenol A (BPA) and 4-tert-butylphenol (4-tBP). The obtained carbon showed bimodal porosity and fast extraction of both pollutants in batch conditions following a pseudo-second-order model. The adsorption mechanism was studied by the measurement of zeta potential, and the results suggested that π-π stacking interactions between the carbon material and the phenol molecules probably are the main sorption mechanism. The prepared C-MIL-125-NH2 was incorporated into mechanically stable membranes for flow-through solid-phase extraction of studied phenols prior to HPLC analysis. The hybrid material showed excellent permeance to flow, easy regeneration and good performance for the simultaneous enrichment of mixtures of BPA and 4-tBP, facilitating their determination when present at low concentration levels.

The photocatalytic activity of boron-doped ZnO with varying concentration (1, 1.5 and 2% wt of B) synthesized by sol-gel method was evaluated on cyanide (CN−) degradation in aqueous solution under simulated solar radiation. The obtained catalysts were characterized by XRD, UV–vis/DRS, ICP-OES, FT-IR, and XPS. The photocatalytic experiments were carried out in a quartz batch reactor using 300 mL of cyanide solution adjusted at pH 11, evaluating different parameters such as the amount of B dopant, catalyst loading and initial concentration of cyanide solution. A 23 central composite faced design was used to maximize CN− photocatalytic degradation. The cyanide concentration was measured by ISE potentiometric method and the content of intermediate ions (OCN−, NO3−, and NH4+) was determined by UV–vis spectrophotometry. The boron incorporation into ZnO lattice (ZnO-B) reduced wurtzite crystallite size (25 nm) and narrowed the band gap (3.0 eV) compared to bare ZnO (43 nm and 3.2 eV, respectively). The ZnO-B 1.5 wt% showed better photocatalytic performance by degrading 89% of a 10 mg L-1 CN− solution compared to 75% that was reached by undoped ZnO; using in both cases 1.4 g L-1 of catalyst loading at accumulated energy of 400 kJ m-2.

In this work, a novel P-doped Fe2O3-TiO2 mixed oxide was successfully prepared by a microwave assisted sol-gel method. The synthesized catalyst was characterized by N2 physisorption, SEM, XRD, XPS, and FTIR, UV–vis DRS, and PL spectroscopies. The iron and phosphorus content in the catalyst samples were quantified by AAS and ICP-OES, respectively. The photocatalytic activity of P-doped Fe2O3-TiO2 powders were evaluated in the photocatalytic degradation of sulfamethazine (SMTZ). The Box Behnken design (BBD) and response surface methodology (RSM) were applied for modeling the effect and optimizing of the operational parameters levels on the degradation percentage of SMTZ. The complete degradation and mineralization percentage of 30% of SMTZ solution at pH 9 was achieved within 300 min of reaction, with the optimum P doping amount of 1.2 wt % and 1.25 g/L of catalyst loading. The 1.2 wt % P-doped Fe2O3-TiO2 mixed oxide showed considerably higher photocatalytic activity than Fe2O3-TiO2 or TiO2. This enhanced performance could be attributed to the small crystallite size, narrow band gap, high specific surface area and increased number of surface hydroxyls on TiO2 nanoparticles. Additionally, the stability and reusability of this catalyst was demonstrated during three cycles of SMTZ degradation.

A fully automated on-line system for monitoring the TiO2-based photocatalytic degradation of dimethyl phthalate (DMP) and diethyl phthalate (DEP) using sequential injection analysis (SIA) coupled to liquid chromatography (LC) with UV detection was proposed. The effects of the type of catalyst (sol–gel, Degussa P25 and Hombikat), the amount of catalyst (0.5, 1.0 and 1.5 g L−1), and the solution pH (4, 7 and 10) were evaluated through a three-level fractional factorial design (FFD) to verify the influence of the factors on the response variable (degradation efficiency, %). As a result of FFD evaluation, the main factor that influences the process is the type of catalyst. Degradation percentages close to 100% under UV-vis radiation were reached using the two commercial TiO2 materials, which present mixed phases (anatase/rutile), Degussa P25 (82%/18%) and Hombikat (76%/24%). 60% degradation was obtained using the laboratory-made pure anatase crystalline TiO2 phase. The pH and amount of catalyst showed minimum significant effect on the degradation efficiencies of DMP and DEP. Greater degradation efficiency was achieved using Degussa P25 at pH 10 with 1.5 g L−1 catalyst dosage. Under these conditions, complete degradation and 92% mineralization were achieved after 300 min of reaction. Additionally, a drastic decrease in the concentration of BOD5 and COD was observed, which results in significant enhancement of their biodegradability obtaining a BOD5/COD index of 0.66 after the photocatalytic treatment. The main intermediate products found were dimethyl 4-hydroxyphthalate, 4-hydroxy-diethyl phthalate, phthalic acid and phthalic anhydride indicating that the photocatalytic degradation pathway involved the hydrolysis reaction of the aliphatic chain and hydroxylation of the aromatic ring, obtaining products with lower toxicity than the initial molecules.

The potential ecological risk of five residual endocrine-disrupting compounds (EDCs) in four wastewater treatment plants (WWTPs) was studied. The wastewater samples were collected in WWTPs of the Metropolitan Area of Monterrey, Mexico (designed as Monterrey City hereinafter) and 17β-estradiol (E2), 17α-ethinylestradiol (EE2), bisphenol A (BPA), 4-nonylphenol (4NP), and 4-tert-octylphenol (4TOP) were studied by SPE/GC-MS method. Results showed that all EDCs are widely distributed in WWTPs, finding high concentrations of BPA (450 ng/L) and EE2 (407.5 ng/L) in influents, while EE2 and 4TOP were the most abundant in effluents at levels from 1.6–26.8 ng/L (EE2) and

The presence of pharmaceuticals classified as emerging contaminants (EC) in surface water, groundwater, and drinking water generates uncertainty concerning the interactions that could be occurred with aquatic organisms and living beings. Thus, the monitoring of hospital wastewater is of great importance to identify the main classes of pharmaceuticals that could be discharged to the municipal sewage system and wastewater treatment plants (WWTPs). This work described the implementation and validation of a highly selective and sensitive analytical method using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the detection and quantification of these emerging compounds. The solid-phase extraction (SPE) method was employed using Oasis HLB cartridges. For LC-MS/MS analysis, the chromatographic separation was conducted in a C-18 Kinetex column (Phenomenex), and detection was achieved in an AB SCIEX QTrap 3200 tandem mass spectrometer (MS/MS) in the multiple reaction monitoring (MRM) mode. The quantitative analysis was performed by using the internal standard (IS) method with isotopically labeled analogs. The implemented method presented good linearity within the concentration range of 0.1–400 µg L-1 showing correlation coefficients (R2) ranged from 0.991 to 0.999. The limits of detection (LODs) were from 0.02 to 0.59 µg L-1, while the limits of quantification (LOQs) ranged from 0.07 to 1.80 µg L-1. The analytical method was successfully applied to the analysis of wastewater samples discharged by a public hospital in San Nicolas de los Garza, Nuevo Leon, Mexico, in two sampling periods: May 2017 and March 2018. Resumen. La presencia de fármacos, clasificados como contaminantes emergentes, en agua superficial, subterránea y potable, genera incertidumbre sobre las interacciones que podrían ocurrir con organismos acuáticos y los seres vivos. Por lo tanto, el monitoreo del agua residual hospitalaria es de gran importancia para identificar los principales productos farmacéuticos que podrían descargarse al sistema de alcantarillado municipal y por lo tanto, estar presentes en el agua a tratar en las plantas de tratamiento de agua residual (PTAR). Este trabajo describe la implementación y validación de un método analítico altamente selectivo y sensible utilizando extracción en fase sólida (SPE) y cromatografía líquida acoplada a espectrometría de masas tándem (LC-MS/MS) para la detección y cuantificación de estos compuestos emergentes. Se empleó el método de extracción en fase sólida utilizando cartuchos Oasis HLB. Para el análisis LC-MS/MS, la separación cromatográfica se realizó en una columna Kinetex C-18 (Phenomenex), y la detección se realizó en un espectrómetro de masas en tándem AB SCIEX QTrap 3200 (MS/MS) en el modo de monitoreo de reacciones múltiples (MRM). El análisis cuantitativo se llevó a cabo utilizando el método de estándar interno (IS) con análogos marcados isotópicamente. El método presentó una buena linealidad dentro del rango de concentración de 0.1 a 400 µg L-1, con coeficientes de correlación (R2) que oscilaron entre 0.991 y 0.999. Los límites de detección (LOD) fueron de 0.02 a 0.59 µg L-1, mientras que los límites de cuantificación (LOQ) variaron de 0.07 a 1.80 µg L-1. El método analítico se aplicó con éxito al análisis de muestras de agua residual vertidas por un hospital público de San Nicolás de los Garza, Nuevo León, México, en dos períodos de muestreo: mayo de 2017 y marzo de 2018.

The presence of emerging contaminants (EC), such as antibiotics in water bodies, is considered an environmental issue. In this work, the iron sources FeC2O4•2H2O (FOD), complexes of iron/oxalate (Fe2+/Ox), and FeSO4 as reference were evaluated as catalysts on the degradation of pyrazinamide (10 mg L−1) antibiotic by the photo-Fenton process. Different parameters were studied such as initial pH value (3, 4.5, and 6), Fe2+/H2O2 molar ratio (1:20, 1:30, and 1:40), and Fe2+/Ox with different molar ratios (1:3, 1:6, and 1:9). The best performance was achieved with a 1:20 Fe2+/H2O2 molar ratio using FeSO4 and FOD showing similar results as FeSO4 catalyst at pH 3 and 4.5. The degradation rate at pH 6 was enhanced using Fe2+/Ox (1:3) compared to FeSO4, and this behavior was explained by Fenton reactants consumption and the oxalate use. The iron source FOD exhibited a poor performance at pH 6 compared with FeSO4; however, FOD activity was notably increased at pH 6 using a greater amount of catalyst, reaching 86.8% of pyrazinamide degradation in 60 min, even higher than using Fe2+/Ox 1:3 complex (68.9%), which makes it a suitable catalyst for the degradation of pyrazinamide by the photo-Fenton process.

In this work, the dispersive solid-phase extraction of sulfonamide antibiotics was evaluated using magnetic porous carbons derived from cobalt(ii)-based metal-organic frameworks. By direct carbonization under the inert atmosphere of Co-SIM-1, Co-MOF-74 and Co-DABCO MOFs, different magnetic porous carbons were prepared and characterized to study their structural, morphological, chemical and textural properties. Their performance for the simultaneous extraction of three sulfonamides (sulfadiazine, sulfamerazine and sulfamethazine), prior to HPLC analysis, was also evaluated, obtaining the best results (>95%) in the case of C/Co-SIM-1 carbon, probably due to its bimodal pore structure, high surface area and large amount of surface defects. Using this adsorbent, the effect of the solution pH and contact time on the adsorption of the sulfonamides, and the reusability of the carbon were studied.

A solid-phase extraction methodology using a MIL-101(Fe)/PVDF membrane was proposed as a useful alternative for the simultaneous determination of naproxen, diclofenac, and ibuprofen, three anti-inflammatory drugs (NSAIDs), in wastewater samples by HPLC-CCD analysis. The MIL-101(Fe) was prepared by a rapid microwave-assisted method and supported in a polymeric PVDF membrane. The prepared material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). The factors that affect the extraction of the NSAIDs using the MIL-101(Fe)/PVDF membrane as the sample volume, the solution pH and the elution solvent were studied in detail. The selected conditions were 50 mL of sample solution at pH 3 and 5 mL of methanol: acetone (30:70, v v−1) acidified with formic acid at 2% as elution solvent. The analytical method was linear with determination coefficients (r2 ≥ 0.998) in the calibration ranges from 2 to 100 ng mL−1 for naproxen, 20–200 ng mL−1 for diclofenac, and 100–300 ng mL−1 for ibuprofen. The intra and inter-day precision (repeatability and reproducibility, respectively) of the method (RSD%, n = 5) were lower than 4.8% and 7.1%, respectively. The accuracy reported as recovery percentages ranged from 82 to 118%, and the limits of detection were between 1.8 and 32.3 ng mL−1. Moreover, MIL-101(Fe)/PVDF membrane exhibited improved adsorption efficiency compared to that of its analog MIL-101(Cr)/PVDF and the pristine PVDF membranes, obtaining in an easy and rapid (60 min) way a low-cost and low-toxic adsorbent with excellent stability, reusability, mechanic resistance, and simple operation which shows excellent performance.

Oxcarbazepine (OXC) an antiepileptic drug, has been detected in wastewater treatment plant (WWTP) effluents, surface, and groundwater in concentrations ranged from µg L−1 to ng L−1. The presence of this drug and its transformation products (TPs) in the aquatic environment creates uncertainty concerning the potential risks to aquatic species and living beings. In this work, the removal of OXC from the water was conducted by photolysis process and heterogeneous photocatalysis using different ZnO-based catalysts. The TPs formed in both reactions were monitored by LC-MS/MS and UPLC-qTOF-MS. The results showed that the OXC was entirely degraded after 30 min of photolysis and photocatalytic reactions. The formation of the main TPs was similar in both processes: nine TPs were detected in the photolysis, while ten products were identified during the heterogeneous photocatalysis. The photolysis reaction was the main responsible for the formation of TPs in both processes, nevertheless, these TPs remained during the photolysis treatment, while its rapid decomposition was achieved in the photocatalytic process. Different degradation pathways were elucidated based on the detection of the generated products. The main degradation reactions were hydroxylation of OXC, heterocyclic ring photo-oxidation, intramolecular ring closure, and HO• radical attack, which led the destruction of the parent compound oxcarbazepine.

The preparation of hierarchical porous carbon sponges (HCS) from metal oxide nanoparticle@metal‐organic frameworks is reported. ZnO nanoparticles are partially converted to zeolitic imidazolate framework‐8 (ZIF‐8) crystals in presence of n‐butylamine to obtain ZnO@ZIF‐8 porous hybrids. After direct carbonization, followed by ZnO acidic etching, ZnO@ZIF‐8 crystals were converted to submicrometric HCS. Due to the high surface area and accessible porosity, combining micro‐ and mesoporosity of HCS, their application for the extraction of water pollutants was studied by preparing HCS/polymer membranes, and showed a high efficiency for the fast (650 L m−2 h−1) removal of plastic degradation by‐products (DBP, dibutyl phthalate. DEHP, bis(2‐n‐ethylhexyl)phthalate). DBP and DEHP breakthroughs were lower than 3 % after the filtration of 100 mL of water containing simultaneously both phthalates at a high concentration level (300 μg L−1, each). HCS/polymer membranes were reusable up to 5 times, maintaining their extraction capacity, with relative errors of 6 % for DBP, and

The sulfamethoxazole (SMX) mineralization through the solar photo electro-Fenton (SPEF) process in a pilot plant containing 20 L of 50 mg L−1 SMX solution was investigated. The process was carried out at pH 3 under different operational conditions varying temperature, volumetric flow and applied current density. Box-Behnken experimental design and response surface methodology (RSM) were used to optimize the experimental variables of the SPEF process. Under the optimal conditions, the SPEF was compared with electro-Fenton (EF) and anodic oxidation (AO- H2O2) processes. Under optimum design variables of 47 mA cm−2, 45 °C and 571 L h−1, SPEF was more efficient yielding 90% of TOC removal after 360 min of reaction with a maximum of 83% of mineralization current efficiency (MCE). The main by-products detected on the final solution treated by SPEF were oxalic, maleic, oxamic and fumaric acids, while NH4+ and NO3− were the main inorganic nitrogen ions released during the process.

A method for the analysis of phthalic acid esters or phthalates (PAEs) in polyethylene terephthalate (PET) bottles based on the use of microwave-assisted extraction (MAE) and liquid chromatography with UV detection (LC-UV) was developed. The microwave-assisted extraction procedure was optimized by a three factors Box–Behnken response surface design. High PAEs recoveries were obtained by microwave-assisted extraction using 70% of acetonitrile at 140 °C during 30 min. Moreover, some physical properties of PET samples as thickness, and crystallization and melting temperatures were determined by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. Those parameters were correlated, through Pearson correlation coefficient, with the content of PAEs determined in PET containers (dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP)) and with the content of PAEs in water obtained from a migration test in PET. The migration procedure was based on a standardized procedure (EU 82/711/EEC and 85/572/EEC directives) stipulated by the European Union (EU). The concentrations of PAEs found in PET bottles were between 1.1 and 14.8 mg kg−1 for DMP, 9.3 and 63.6 mg kg−1 for DBP and DEP was only detected in one of the 10 analyzed samples at a concentration of 3.1 mg kg−1. The analysis of the samples obtained by applying the migration test showed that DBP was found in five of the ten analyzed samples reaching concentrations from 14.5 up to 25.6 μg L−1. DMP was found in five of the ten analyzed samples, with concentrations from 4.1 to 50.6 μg L−1, whereas DEP was not detected in any of the analyzed samples. The results of the Pearson correlation coefficient indicated that there was a significant correlation between the thickness and the total concentration of PAEs in the PET samples (95% confidence interval), as well as the DBP content in PET samples and the concentration of DBP migrated from bottles to the water (90% confidence interval), indicating that the content of PAEs in the samples and the migration rate of these compounds was related to the physical characteristics of PET bottles.

Mesoporous phosphorous-doped TiO2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol–gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV–Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O–H bond were observed by FTIR analysis compared with bare TiO2. The P was substitutionally incorporated in the TiO2 lattice network as P5+ replacing Ti4+ to form Ti–O–P bonds and additionally present as PO43− on the TiO2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO2 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.

Photocatalytic degradation of p-Cresol was evaluated using the mixed oxide Bi2O3/TiO2 (containing 2 and 20% wt. Bi2O3 referred as TB2 and TB20) and was compared with bare TiO2 under simulated solar radiation. Materials were prepared by the classic sol-gel method. All solids exhibited the anatase phase by X-ray diffraction (XRD) and Raman spectroscopy. The synthesized materials presented lower crystallite size and Eg value, and also higher surface area as Bi2O3 amount was increased. Bi content was quantified showing near to 70% of theoretical values in TB2 and TB20. Bi2O3 incorporation also was demonstrated by X-ray photoelectron spectroscopy (XPS). Characterization of mixed oxides suggests a homogeneous distribution of Bi2O3 on TiO2 surface. Photocatalytic tests were carried out using a catalyst loading of 1 g L-1 under simulated solar light and visible light. The incorporation of Bi2O3 in TiO2 improved the photocatalytic properties of the synthesized materials obtaining better results with TB20 than the unmodified TiO2 under both radiation sources.

In this study, samples of ZnO modified with copper (II) phthalocyanine (CuPc) (0.1% and 0.5% wt) were synthesized via the sol-gel method. The catalysts were characterized by DTA-TGA analysis, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Ultraviolet diffuse reflectance spectroscopy (DRS-UV) was used to estimate the band gap energy (Eg) of the prepared materials, and the textural properties of the solids were determined from N2 adsorption isotherms. The photocatalytic activity of the ZnO-CuPc catalysts was evaluated on the degradation of the methylene blue (MB) and potassium cyanide (KCN) under UV and visible light. The dye concentration was determined spectrophotometrically at 665 nm during the treatment. The CN- content during the photocatalytic reaction was analyzed potentiometrically using a cyanide ion-selective electrode. Both pollutants were completely degraded under both light sources; however, the highest degradation rate was observed for MB decomposition achieving complete degradation in 150 min.

Nickel-doped TiO2 (0.1, 0.5, 1.0, 2.5, 5.0, and 10.0 wt%) photocatalysts were prepared by the sol–gel method. Physicochemical properties were determined by the characterization using X-ray diffraction, Raman and UV–vis diffuse reflectance spectroscopies, N2 physisorption, and zeta potential determination (PZC). The synthesized materials exhibited the photocatalytically active anatase crystalline phase and the catalysts exhibited stronger absorption in the visible light region with a red shift in the adsorption edge with the increase of Ni doping. The photocatalytic evaluation of TiO2−Ni materials was carried out on p-arsanilic acid (p-ASA, 10 mg L−1) degradation in aqueous suspension under visible radiation. Compared with bare TiO2, the TiO2–Ni 1.0 material (1 wt% Ni-doped TiO2) exhibited higher photocatalytic activity on p-ASA degradation under visible light irradiation allowing a 76% degradation percentage in 180 min reaction time while 60% degradation percentage was achieved with undoped TiO2. The TiO2–Ni 1.0 material showed the highest surface area in comparison with the other prepared materials. Meanwhile, the photocatalytic activity of TiO2–Ni 1.0 can keep even after three cycles with not loss of activity since nickel was not leached from the TiO2-based catalyst into the solution during photocatalytic reaction. Therefore, the doping of the nickel into the TiO2 lattice by the sol–gel method allowed its activation under visible radiation and an efficient photoexcited charge separation to prevent electron-hole recombination showing high chemical stability.

In this work, heterogeneous photocatalysis under visible light was applied as treatment to degrade bisphenol A (BPA) using Ni-TiO 2 catalysts with different Ni contents (0.5 and 1.0 wt%). The materials were synthesized by rapid microwave assisted sol-gel process (MW). For comparison, 1.0% Ni-TiO 2 by conventional sol-gel method (CM) was prepared. Semiconductors were characterized by various analytical techniques. Diffuse reflectance spectroscopy studies indicated a red shift in the band gap absorption to the visible region when nickel was incorporated while results from powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed the substitution of sites of Ti 4+ ions by Ni 2+ ions into the crystal lattice of anatase TiO 2 . The best results in BPA degradation were obtained at solution pH 9 in the follow order 1.0% Ni-TiO 2 MW > 0.5% Ni-TiO 2 MW > 1.0% Ni-TiO 2 CM > TiO 2 MW. This behavior was explained by the lower band gap (Eg) value, smaller crystallite size and the inhibition in recombination of the electron/hole pairs, caused by nickel incorporation. Using 1.0% Ni-TiO 2 MW as catalyst, complete BPA degradation, and 77% mineralization were achieved in 210 min. The toxicity of the final solution was also evaluated by means of the marine bacteria Vibrio fischeri .

In the present work, an alternative system of 5-hydroxymethylfurfural (HMF) oxidation was studied, in an effort to avoid the use of expensive precious metal catalysts, high pressures and systems not environmentally friendly. The catalysts tested were Co (II), Fe (II) and Cu (II) Salen complexes supported on SBA-15 (Co Salen/SBA-15, Fe Salen/SBA-15 and Cu Salen/SBA-15 respectively). The reaction was carried out in aqueous medium at room temperature (25 °C ± 1) and atmospheric pressure, using hydrogen peroxide (H 2 O 2 ) as the only oxidant agent. The effect of various reaction conditions such as H 2 O 2 content, oxidant agent amount, different transition metals present in the catalyst and temperature were evaluated. The HMF and the reaction products such as; 2,5-diformylfuran (DFF), 2,5-furandicarboxylic acid (FDCA), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) and 5-formyl-2-furancarboxylic acid (FFCA) were followed by high performance liquid chromatography (HPLC) measurements. The selectivity and reaction kinetics under different reaction conditions was studied. The different synthesized catalysts were extensively characterized by UV–vis spectroscopy, subsequently by FTIR, DR-UV–vis, AA and XPS spectroscopy and through nitrogen physorption, which was related to its catalytic activity. The successful synthesis of SBA-15 support was confirmed by its textural properties and STEM. From the experimental data obtained a reaction mechanism with parallel reactions was proposed founding that the oxidation route of the alcohol group in HMF is favored over of the oxidation of the aldehyde group on the other side of the molecule.

The development of a new method to determine the presence of the organoarsenic additives p -arsanilic acid (ASA), roxarsone (ROX) and nitarsone (NIT) in livestock feeds by high performance liquid chromatography coupled to ultraviolet oxidation hydride generation atomic fluorescence spectrometry (HPLC-UV/HG-AFS) after microwave assisted extraction (MAE) was proposed. Chromatographic separation was achieved on a C18 column with 2% acetic acid/methanol (96:4, v/v) as the mobile phase. The limits of detection (LODs) were 0.13, 0.09 and 0.08 mg L −1 , and the limits of quantification (LOQs) were 0.44, 0.30 and 0.28 mg L −1 . The relative standard deviations (RSDs) for ASA, ROX and NIT determined from five measurements of the mixed calibration standard were 3.3, 5.3, and 5.4%, respectively. MAE extraction of phenylated arsenic compounds using 1.5 M H 3 PO 4 at 120 °C for 45 min allowed for maximum recoveries (%) of total arsenic (As) and organoarsenic species, with no degradation of these compounds. The extraction of total As was approximately 97%, and the As species recoveries were between 95.2 and 97.0%. The results of the analysis were validated using mass balance by comparing the sum of extracted As with the total concentration of As in the corresponding samples. The method was successfully applied to determine the presence of these compounds in feed samples. ASA was the only As species detected in chicken feed samples, with a concentration between 0.72 and 12.91 mg kg −1 .

Several compounds of the phthalate family are widely applied as additives for polymers as polyvinyl chloride (PVC) and polyethylene terephthalate (PET). These compounds are not part of the polymer chains, and therefore, they can be released easily from products and migrate into beverages that come into direct contact causing environmental and human health impacts. Because of this, certain phthalates (PAEs) have been identified as priority pollutants by the European Union (EU), US Environmental Protection Agency (EPA) and other international organizations. Due to that the concentration of these compounds in beverages is found at very low level, a pretreatment step prior to their analysis is necessary; thus, several sample preparation methods have been described, such as liquid–liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), and liquid-phase microextraction (LPME). Chromatographic techniques such as gas chromatography (GC) coupled to mass spectrometry (MS) or liquid chromatography (LC) with UV detector, diode array detector (DAD), and MS have been used to analyze PAEs. Additionally, non-chromatographic techniques such as electrochemical sensors and immunoassay-based techniques have been described for PAE analysis in beverages. This review provides an overview of the different analytical techniques for PAE quantification in beverages and their plastic containers, focused in the last 10 years published works, covering the sample preparation and determination, as well as the legislation and the evaluation of main factors that could promote the migration of these plasticizers from polymers into beverages.

The catalyst FeTiO3/ZnO was prepared by ultrasound-assisted chemical precipitation method. The material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). FeTiO3/ZnO (1, 5, and 10%wt. FeTiO3) was evaluated on photocatalytic degradation of ciprofloxacin (CPX) in an aqueous solution (10 mg L−1) under UV-Vis irradiation. The heterojunction between FeTiO3 and ZnO, the presence of Fe2O3 impurities, and the formation of oxygen vacancies allowed the coupled material FeTiO3/ZnO (1%wt.) showed a better photocatalytic performance (100% degradation CPX and 27% of mineralization) than bare ZnO. Although ZnO also attained complete degradation of CPX, the antibiotic was not mineralized under the same operating conditions. A scavenger study determined that h+ and OH were the principal reactive species involved in the CPX photocatalytic degradation. The heterostructured material showed high stability and reusability during three cycles of use.

In this work, BiOBr photocatalyst co-doped with Fe and N (Fe–BiOBr–N) was synthesized by a microwave-assisted solvothermal method. This material was characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, N2 adsorption-desorption, X-ray photoelectronic spectrometry, UV–Vis diffuse reflectance spectroscopy, atomic absorption spectroscopy, elemental analysis, and photoluminescence techniques. The characterization of this material revealed the formation of flower-like structures and the successful incorporation of Fe and N in BiOBr. The incorporation of Fe and N in BiOBr caused a decrease of the band gap (from 2.87 to 1.92 eV), the crystal size (from 12.93 to 8.43 nm), and the recombination rate of photogenerated charges compared with unmodified BiOBr. Likewise, these dopants caused an increase in specific surface area (from 7 to 16 m2/g). The photocatalytic activity was assessed on the elimination of bisphenol A (BPA) under visible radiation. Fe–BiOBr–N exhibited higher photocatalytic activity than pristine BiOBr on the BPA degradation, allowing complete degradation and 65% of mineralization in 240 min, while using pristine BiOBr 40% of degradation and 20% of mineralization were obtained. Fe–BiOBr–N is a promising option for the effective elimination of persistent contaminants such as BPA in the aqueous medium, under visible radiation.

In this research study, WO3/NaNbO3-coupled photocatalysts were synthesized at three WO3 mass ratios (15, 85, and 95 wt%) and characterized. These composites were characterized via X-ray powder diffraction, N2 physisorption, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and photoluminescence techniques. For comparison, bare WO3 and NaNbO3 were also synthesized and characterized. 2,4-Dichlorophenoxyacetic acid (2,4-D) was degraded under visible light to evaluate its photocatalytic performance. The WO3 (95 wt%)/NaNbO3 composite showed higher photocatalytic activity than pure WO3 and NaNbO3 and even than the 15 and 85 wt% coupled materials; thus, the combination with the highest ratio of WO3 with respect to NaNbO3 showed increased photocatalytic activity compared with the bare materials.

The use of semiconductor photocatalysis is a promising, green, and sustainable technology to address solar energy conversion and environmental remediation issues. Among photocatalytically active semiconductors, considerable attention has been given to the visible-light active tungsten oxide (WO3, Eg value ≈ 2.7–3.1 eV). This semiconductor has several advantages: strong absorption in the visible spectrum range, stability in acidic and oxidative conditions, low cost, and low toxicity. However, WO3 presents fast recombination of charge carriers’ and exhibits low photocatalytic activity for reduction reactions due to its conduction band potential (+0.5 V versus NHE). Many strategies have been applied to enhance photocatalytic activity and solar energy utilization of WO3 by modifying the energy band position and reducing the charge carrier recombination. In this review, several approaches, such as designing with exposed facets and specific morphologies, doping with transition metals and non-metals, deposition of noble metals, and heterojunction construction, are summarized. Moreover, the photocatalytic properties of the reviewed WO3-based photocatalysts are discussed based on their environmental applications such as degradation of organic pollutants, air purification, CO2 photoreduction, hydrogen production from water splitting and recently, simultaneous wastewater treatment and electric energy generation by photocatalytic fuel cells. Finally, the summary, future perspectives, and challenges of design novel WO3-based photocatalysts with high efficiency are pointed out to meet the urgent demands of highly efficient technologies that use visible or solar energy for environmental applications.

In this study, the photocatalytic removal of an emerging contaminant, diclofenac (DCF) sodium, was performed using the nitrogen-doped WO3/TiO2-coupled oxide catalyst (WO3/TiO2-N). The catalyst synthesis was accomplished by a sol–gel method using tetrabutyl orthotitanate (C16H36O4Ti), ammonium p-tungstate [(NH4)10H2W12O42·4H2O] and ammonium nitrate (NH4NO3) as the nitrogen source. For comparison, TiO2 and WO3/TiO2 were also prepared under similar conditions. Analysis by X-ray diffraction (XRD), N2 adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV–Vis spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the synthesized materials. The photocatalytic efficiency of the semiconductors was determined in a batch reactor irradiated with simulated solar light. Residual and mineralized DCF were quantified by high-performance liquid chromatography, total organic carbon analysis and ion exchange chromatography. The results indicated that the tungsten atoms were dispersed on the surface of TiO2 as WO3. The partial substitution of oxygen by nitrogen atoms into the lattice of TiO2 was an important factor to improve the photocatalytic efficiency of WO3/TiO2. Therefore, the best photocatalytic activity was obtained with the WO3/TiO2-N0.18 catalyst, reaching 100% DCF transformation at 250 kJ m−2 and complete mineralization at 400 kJ m−2 of solar-accumulated energy.

Photocatalytic degradation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution using Cr(III)-doped TiO2 under UV and visible light was investigated. The semiconductor material was synthesized by a microwave-assisted sol–gel method with Cr(III) doping contents of 0.02, 0.04, and 0.06 wt%. The catalyst was characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption, UV–Vis diffuse reflectance spectroscopy (DRS), and atomic absorption spectroscopy (AAS). The photocatalytic activity for the photodegradation of MCPA was followed by reversed-phase high-performance liquid chromatography (HPLC) and total organic carbon (TOC) analysis. The intermediates formed during degradation were identified using gas chromatography–mass spectrometry (GC–MS). Chloride ion evolution was measured by ion chromatography. Characterization results showed that Cr(III)-doped TiO2 materials possessed a small crystalline size, high surface area, and mesoporous structure. UV–Vis DRS showed enhanced absorption in the visible region as a function of the Cr(III) concentration. The Cr(III)-doped TiO2 catalyst with 0.04 wt% of Cr(III) was more active than bare TiO2 for the degradation of MCPA under both UV and visible light. The intermediates identified during MCPA degradation were 4-chloro-2-methylphenol (CMP), 2-(4-hydroxy-2-methylphenoxy) acetic acid (HMPA), and 2-hydroxybuta-1,3-diene-1,4-diyl-bis (oxy)dimethanol (HBDM); the formation of these intermediates depended on the radiation source.

A simple, inexpensive and rapid method was proposed for the determination of bioaccessible arsenic in corn and rice samples using an in vitro bioaccessibility assay. The method was based on the preconcentration of arsenic by cloud point extraction (CPE) using o,o-diethyldithiophosphate (DDTP) complex, which was generated from an in vitro extract using polyethylene glycol tert-octylphenyl ether (Triton X-114) as a surfactant prior to its detection by atomic fluorescence spectrometry with a hydride generation system (HG-AFS). The CPE method was optimized by a multivariate approach (two-level full factorial and Doehlert designs). A photo-oxidation step of the organic species prior to HG-AFS detection was included for the accurate quantification of the total As. The limit of detection was 1.34μgkg(-1) and 1.90μgkg(-1) for rice and corn samples, respectively. The accuracy of the method was confirmed by analyzing certified reference material ERM BC-211 (rice powder). The corn and rice samples that were analyzed showed a high bioaccessible arsenic content (72-88% and 54-96%, respectively), indicating a potential human health risk.

The improved photocatalyst carbon-doped WO 3 /TiO 2 mixed oxide was synthesized in this study using the sol–gel method. The catalyst was thoroughly characterized by X-ray diffraction (XRD), diffuse reflectance UV–vis spectroscopy, N 2 adsorption desorption analysis, scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic efficiency of the prepared materials was evaluated with respect to the degradation of sodium diclofenac (DCF) in a batch reactor irradiated under simulated solar light. The progress of the degradation process of the drug was evaluated by high-performance liquid chromatography (HPLC), whereas mineralization was monitored by total organic carbon analysis (TOC) and ion chromatography (IC). The results of the photocatalytic evaluation indicated that the modified catalyst with tungsten and carbon (TWC) exhibited higher photocatalytic activity than TiO 2 (T) and WO 3 /TiO 2 (TW) in the degradation and mineralization of diclofenac (TWC>TW>T). Complete degradation of diclofenac occurred at 250 kJ m −2 of accumulated energy, whereas 82.4% mineralization at 400 kJ m −2 was achieved using the photocatalytic system WO 3 /TiO 2 -C. The improvement in the photocatalytic activity was attributed to the synergistic effect between carbon and WO 3 incorporated into the TiO 2 structure.

Five endocrine-disrupting compounds (EDCs) were determined in four urban wastewater treatment plants (WWTPs) of the Metropolitan Area of Monterrey (MAM) in two seasonal periods (winter and summer). The MAM, one of the most urbanized areas in Mexico, is characterized by high industrial activity and population density, leading to extensive use of several EDCs. In the MAM, ∼90% of urban and industrial wastewater is treated in WWTPs, where EDCs can be partially eliminated. In this work, dissolved levels of 17β-estradiol (E2), 17α-ethinyl estradiol (EE2), bisphenol A (BPA), 4-nonylphenol (4NP), and 4-tert-octylphenol (4TOP) in wastewater were determined. The EDCs' determination was carried out through solid-phase extraction (SPE) and gas chromatography coupled to mass spectrometry (GC-MS). High EDCs levels (0.4-450 ng/L) were found in the influents of WWTPs, while concentrations in the effluents ranged from 0.2 to 26.8 ng/L, with E2, EE2, and 4TOP being the most persistent. The Spearman correlation analysis revealed the association between E2 and EE2 (r = 0.4835, p 0.05), and between BPA and 4NP (r = 0.5180, p 0.05), suggesting that these EDCs have similar sources. Also, E2, BPA, and 4TOP were positively correlated with the chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) (r = 0.4080-0.5694, p 0.05), indicating the association of the EDCs with the organic matter in the wastewater. The factor analysis confirmed the significant correlation of COD, BOD, TSS, temperature, and pH with the high occurrence of 4TOP during the summer. It was also confirmed that summer warmer temperatures favored the removal of BPA and 4NP in the studied WWTPs. Finally, the studied sites were classified by cluster analysis in three groups, revealing the impact that seasonality has on the behavior of the selected EDCs.

The mercury pollution of the soil and water environments in a mining area of Villa Hidalgo, San Luis Potosi, Mexico, and its effects on the area's soil characteristics were evaluated. Soil and water were collected from seven localities in Villa Hidalgo in the autumn of 2016. The physicochemical and mineralogical characteristics of the soil samples were analyzed. Water samples were obtained from wells used for human activities, such as irrigation, housework, and human consumption. The total mercury (THg) content in the water at the monitoring sites was lower than the threshold value and related to some physicochemical water quality parameters. Regarding soil characteristics, the samples were mainly composed by O, Si, Ca, Al, and Fe, and the associated minerals included grossularite, labradorite, and orthoclase. The distribution of the Hg fractions and Hg species in the soil samples were investigated; the THg content ranged from 0.34 to 41.76 mg kg−1, which exceeded the national regulations for a single site. The residual mercury was the main Hg fraction in the soils, and methylmercury was not detected. The relationships between the mercury fractions and the physicochemical and mineralogical characteristics of the soils demonstrated that low organic carbon content and high concentrations of iron, aluminum, and calcium are the most important factors that affect the soil fraction distribution and low mercury mobility in the area. These results could indicate the association of mercury with sulfides, silicates, and crystalline oxides of iron and manganese. A relatively low degree of potential risk for the population (children and adults) was corroborated with the results of the hazard indexes (HI: 3.0 × 10−2 – 2.1 × 10−1); however, these values can be underestimated, since there could be other Hg exposure sources.

Phosphorous-doped Ti-Fe mixed oxide (P-TiO2-αFe2O3) catalysts were prepared by the microwave-assisted sol-gel route and characterized using XRD, SEM, N2 physisorption, UV–vis diffuse reflectance, FTIR, and XPS. P-TiO2-αFe2O3 was evaluated during the degradation of a sulfonamide mixture (5 mg/L, each) under visible light. The photocatalytic process was optimized with a face-centered central composite design. Under optimal conditions (0.5 wt% of αFe2O3, pH 10, and 0.75 g/L of catalyst loading), the sulfate radical advanced oxidation process was carried out using 5 mM K2S2O8 (PS). P doping shifted the light absorption of P-TiO2-αFe2O3 in the visible light range owing to substitutional doping, while the coupling of P-TiO2 with α-Fe2O3 enhanced the absorption in the visible range, which resulted in an increase in the lifetime of the charge carriers and in a superior photoactivity of the P-TiO2-αFe2O3 catalyst in comparison to that of TiO2. The mineralization yield of the sulfonamides (SNs) mixture was enhanced in the presence of an electron acceptor (SO4− ), allowing nearly 69 % within 300 min with the P-TiO2-αFe2O3/PS system, while P-TiO2-αFe2O3 and K2S2O8 oxidation achieved only 27 % and 21 %, respectively. The biodegradability index was 0.48 using the P-TiO2-αFe2O3/PS system, indicating a less toxic effluent than the original compounds. Recycling tests demonstrated that P-TiO2-αFe2O3 exhibits good stability in activating PS for SNs degradation during three cycles. Two main intermediates (pyrimidine and hydroquinone) and their hydroxylated re-arrangements were detected during the degradation of the SNs by the coupled process. Oxalic, oxamic, sulfonic, and acetic acids were also identified as by-products from the degradation of the SNs.

The photocatalytic degradation of a sodium diclofenac (DCF) solution (10 mg/L) under simulated solar radiation was evaluated using a ZnO semiconductor modified by the incorporation of 10, 15, and 20 wt.% fluorine (ZnO-F10, ZnO-F15 and ZnO-F20). The ZnO-F catalysts were synthesized by the sol-gel method using zinc acetate as a precursor of zinc oxide and NH4F as a fluorine source. The photocatalytic performance of the F-doped ZnO material was compared to that of bare ZnO. The obtained photocatalysts were characterized using X-ray diffraction (XRD), Scanning electron microscopy with Energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) techniques. The Brunauer-Emmett-Teller (BET) surface area, pH of zero charge (pHpzc), and band gap of the solids were also evaluated. An experimental Box-Behnken design combined with response surface methodology was applied to establish the optimal conditions for the photocatalytic degradation of the DCF solution. Complete DCF degradation, total release of chloride ions, and approximately 90% mineralization were achieved during degradation of the drug at an accumulated energy of 400 kJ/m2 under the optimized experimental conditions (1 g/L of ZnO-F20 catalyst with the pH of the DCF solution maintained at 6.5).

A fully automated on-line system for monitoring the TiO2-based photocatalytic degradation of dimethyl phthalate (DMP) and diethyl phthalate (DEP) using sequential injection analysis (SIA) coupled to liquid chromatography (LC) with UV detection was proposed. The effects of the type of catalyst (sol-gel, Degussa P25 and Hombikat), the amount of catalyst (0.5, 1.0 and 1.5 g L-1), and the solution pH (4, 7 and 10) were evaluated through a three-level fractional factorial design (FFD) to verify the influence of the factors on the response variable (degradation efficiency, %). As a result of FFD evaluation, the main factor that influences the process is the type of catalyst. Degradation percentages close to 100% under UV-vis radiation were reached using the two commercial TiO2 materials, which present mixed phases (anatase/rutile), Degussa P25 (82%/18%) and Hombikat (76%/24%). 60% degradation was obtained using the laboratory-made pure anatase crystalline TiO2 phase. The pH and amount of catalyst showed minimum significant effect on the degradation efficiencies of DMP and DEP. Greater degradation efficiency was achieved using Degussa P25 at pH 10 with 1.5 g L-1 catalyst dosage. Under these conditions, complete degradation and 92% mineralization were achieved after 300 min of reaction. Additionally, a drastic decrease in the concentration of BOD5 and COD was observed, which results in significant enhancement of their biodegradability obtaining a BOD5/COD index of 0.66 after the photocatalytic treatment. The main intermediate products found were dimethyl 4-hydroxyphthalate, 4-hydroxy-diethyl phthalate, phthalic acid and phthalic anhydride indicating that the photocatalytic degradation pathway involved the hydrolysis reaction of the aliphatic chain and hydroxylation of the aromatic ring, obtaining products with lower toxicity than the initial molecules.

An automated method for the analysis of methylparaben, propylparaben, benzophenone-3, and benzophenone-4 in water effluents via on-line solid-phase extraction coupled with high-performance liquid chromatography/ultraviolet detection was proposed. The preconcentration parameters were studied using Plackett-Burman and Box-Behnken experimental designs using a C18 sorbent material. The results demonstrated that the eluent volume, composition, and sorbent amount were statistically significant. Optimal conditions for these variables were an eluent volume of 1.55 mL, eluent composition of acetonitrile 100% v/v, and sorbent amount of 100 mg. The eluted sample was analyzed on-line using high-performance liquid chromatography equipped with a reversed-phase C18 column and ultraviolet detection. Separation of the analytes was achieved in 15 min using gradient elution with acetonitrile/water. A simple, sensitive, and rapid analytical method was proposed for personal care compounds without sophisticated or expensive equipment. The limits of detection were 1.20, 1.73, 2.51, and 4.67 μg/L for propylparaben, methylparaben, benzophenone-3, and benzophenone-4, respectively. The analysis time was 48 min, consuming only 1.59 mL of eluent acetonitrile for the solid phase extraction step, with minimal sample handling. The method was applied to the analysis of spiked swimming pool and wastewater, with recoveries between 65-107%. These results indicate the reliability of the flow-based procedure.