Person: Ovejero Escudero, Gabriel
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First Name
Gabriel
Last Name
Ovejero Escudero
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
Ingeniería Química
Identifiers
3 results
Search Results
Now showing 1 - 3 of 3
Item Degradation Kinetics of Bisphenol A by Catalytic Wet Oxidation with Ruthenium-Impregnated Carbon Nanosphere Catalysts(chemistry proceedings, 2022) Serra-Pérez, Estrella; Ovejero Escudero, Gabriel; García Rodríguez, JuanDifferent countries in Europe have proposed some restrictions about bisphenol A (BPA), considered an endocrine disruptor, for the production of food packing and toys for children, for example, Denmark, France, Sweden, Belgium, Austria and Norway. However, it is still being found in wastewater effluents. In this study, BPA was degraded by catalytic wet air oxidation employing ruthenium-impregnated carbon nanosphere catalysts (CNS). The catalyst was synthesized with a mixture of resorcinol and formaldehyde and later, a pyrolysis treatment was impregnated by 1, 2, 5, 7 and 10% of ruthenium and activated with hydrogen at 350 °C. The experimental installation was a batch Hastelloy high-pressure reactor of 100 mL of volume with an electrical jacket and a variable-speed magnetic drive. The concentration of BPA was followed by high-performance liquid chromatography. After the study of different experiment variables (temperature (110–150 °C), pressure (20–50 bar), initial concentration of BPA (5–30 mg L−1) and catalyst mass (50–300 mg)) in a batch reactor of 100 mL of volume, two different potential models (r = k CaBPA and r = k CaBPA Pb Cc Ru) were used for simulating the kinetic behavior of BPA from the adjustment of the experimental data obtained for CWAO reactions. It also tested different loads of ruthenium (1–10%) in BPA degradation. Both adjustments had a correlation factor of 0.98 and reproduced all the experiments well, being better than those ones with 20 mg L−1 of initial concentration of BPA. BPA degradation was above 97% at 90 min of reaction time from 2% of Ru in the catalyst.Item Enhancement of p-nitrophenol adsorption capacity through N2-thermal-based treatment of activated carbons(Applied Surface Science, 2017) Álvarez-Torrellas, S.; Martin-Martinez, M.; Gomes, H.T.; Ovejero Escudero, Gabriel; García González, JuliánIn this work several activated carbons showing different textural and chemical properties were obtained by chemical and physical activation methods, using a lignocellulosic material (peach stones) as precursor. The activated carbon resulting from the chemical activation, namely as CAC, revealed the best textural properties (SBET = 1521 m2 g−1, pore volume = 0.90 cm3 g−1) and an acidic character. It was found that the activated carbon obtained at 300 °C (under air atmosphere, PAC_air), and those synthesized at 750 °C in presence of N2 flow with bubbling of water/12 M H3PO4 solution (PAC_N2(H2O)/PAC_N2(H3PO4)), respectively, revealed worse textural properties, compared to CAC. Two functionalization treatments, by using sulphuric acid at boiling temperature (PACS) and nitric acid-urea-N2 heating at 800 °C (PAC-NUT), were applied to PAC_air, in order to enhance the adsorption ability of the carbon material. Several techniques were carried out to characterize the physical and chemical properties of the obtained carbon materials. The modification treatments had influence on the carbon surface properties, since the nitric acid-urea-N2 heating treatment led to a carbon material with highly-improved properties (SBET = 679 m2 g−1, pHIEP = 5.3). Accordingly, the original and modified-carbon materials were tested as adsorbents to remove 4-nitrophenol (4-NP), assessing batch and fixed-bed column adsorption tests. PAC-NUT carbon offered the best adsorption behavior (qe = 234 mg g−1), showing a high ability for the removal of 4-NP from water.Item Magnetite-Based Catalyst in the Catalytic Wet Peroxide Oxidation for Different Aqueous Matrices Spiked with Naproxen–Diclofenac Mixture(Catalysts, 2021) Huaccallo-Aguilar, Ysabel; Álvarez-Torrellas, Silvia; Martínez-Nieves, Johanny; Delgado-Adámez, Jonathan; Gil, María Victoria; Ovejero Escudero, Gabriel; García, JuanMagnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and naproxen (NAP) from an aqueous solution at different conditions (pH, temperature, and hydrogen peroxide) to determine the optimum conditions for chemical oxidation. The optimization of the process parameters was conducted using response surface methodology (RSM) coupled with Box–Behnken design (BBD). By RSM–BBD methodology, the optimal parameters (1.75 mM H2O2 dosage, 70 °C and pH 6.5) were determined, and the removal percentages of NAP and DCF were 19 and 54%, respectively. The NAP–DCF degradation by catalytic wet peroxide oxidation (CWPO) was caused by •OH radicals. In CWPO of mixed drug solutions, DCF and NAP showed competitive oxidation. Hydrophobic interactions played an important role during the CWPO process. On the other hand, the magnetic catalyst reduced its activity after the second cycle of reuse. In addition, proof of concept and disinfection tests performed at the operating conditions showed results following the complexity of the water matrices. In this sense, the magnetic catalyst in CWPO has adequate potential to treat water contaminated with NAP–DCF mixtures.