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Gabriel Ovejero  - - - 
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Silvia Álvarez-Torrellas

9 shared publications

Catalysis and Separation Processes Group, Chemical Engineering and Materials Department, Faculty of Chemistry, Complutense University, Avda. Complutense s/n, 28040 Madrid, Spain

Juan García

4 shared publications

Catalysis and Separation Processes Group, Chemical Engineering and Materials Department, Faculty of Chemistry, Complutense University, Avda. Complutense s/n, 28040 Madrid, Spain

José Antonio Delgado

1 shared publications

Catalysis and Separation Processes Group, Chemical Engineering and Materials Department, Faculty of Chemistry, Complutense University, Avda. Complutense s/n, 28040 Madrid, Spain

Marcos Larriba

1 shared publications

Catalysis and Separation Processes Group, Chemical Engineering and Materials Department, Faculty of Chemistry, Complutense University, Avda. Complutense s/n, 28040 Madrid, Spain

V. Ismael Águeda

1 shared publications

Catalysis and Separation Processes Group, Chemical Engineering and Materials Department, Faculty of Chemistry, Complutense University, Avda. Complutense s/n, 28040 Madrid, Spain

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Article 1 Read 0 Citations Optimization Parameters, Kinetics, and Mechanism of Naproxen Removal by Catalytic Wet Peroxide Oxidation with a Hybrid I... Ysabel Huaccallo-Aguilar, Silvia Álvarez-Torrellas, Marcos L... Published: 20 March 2019
Catalysts, doi: 10.3390/catal9030287
DOI See at publisher website ABS Show/hide abstract
This work presents a study of the assessment of the operating parameters of the catalytic wet peroxide oxidation (CWPO) of naproxen (NAP) using magnetite/multi-walled carbon nanotubes (Fe3O4/MWCNTs) as a catalyst. The effect of pH, temperature, and H2O2 dosage on CWPO process was evaluated by using the response surface model (RSM), allowing us to obtain an optimum NAP removal of 82% at the following operating conditions: pH = 5, T = 70 °C, [H2O2]0 = 1.5 mM, and [NAP]0 = 10.0 mg/L. Therefore, NAP degradation kinetics were revealed to follow a pseudo-second-order kinetic model, and an activation energy value of 4.75 kJ/mol was determined. Adsorption and using only H2O2 experiments, both considered as blank tests, showed no significant removal of the pollutant. Moreover, Fe3O4/MWCNTs material exhibited good recyclability along three consecutive cycles, finding an average NAP removal percentage close to 80% in each cycle of 3 h reaction time. In addition, the scavenging tests confirmed that the degradation of NAP was mainly governed by •OH radicals attack. Two reaction sequences were proposed for the degradation mechanism according to the detected byproducts. Finally, the versatility of the catalyst was evidenced in the treatment of different environmentally relevant aqueous matrices (wastewater treatment plant effluent (WWTP), surface water (SW), and a hospital wastewater (HW)) spiked with NAP, obtaining total organic carbon (TOC) removal efficiencies after 8 h in the following order: NAP-SW > NAP-HW > NAP-WWTP.
PROCEEDINGS-ARTICLE 10 Reads 0 Citations Removal of isoproturon from aqueous solution by adsorption onto a commercial activated carbon Silvia Alvarez, Gabriel Ovejero, Araceli Rodríguez, Juan Gar... Published: 16 November 2016
Proceedings of The 1st International Electronic Conference on Water Sciences, doi: 10.3390/ecws-1-c004
DOI See at publisher website ABS Show/hide abstract
INTRODUCTION Nowadays the number of hazardous compounds occurring in the water environment is increasing. The substances called as priority compounds, detailed in the Water Framework Directive (2000/60/CE), are of special concern; pesticides such as isoproturon are included in this category. The objective of this experimental work was to evaluate the removal of isoproturon from water by adsorption onto a commercial activated carbon. Equilibrium and dynamic adsorption experiments were carried out. MATERIALS AND METHODS Isoproturon was used in the experiments without any further purification. Ultrapure water was used in the adsorption tests. Granular activated carbon supplied by Calgon was used in the study. Batch adsorption experiments were accomplished, in order to study the kinetic and equilibrium adsorption data. Therefore, fixed-bed adsorption tests were carried out, obtaining the breakthrough curves of the system. Isoproturon concentration in the samples was determined by HPLC technique. RESULTS AND DISCUSSION The equilibrium time onto Calgon F400 activated carbon was achieved after 300 hours. The obtained equilibrium adsorption isotherm could be classified as L1-type, according to Giles classification, with a maximum adsorption capacity of 316 mg.g-1. As a result of the fixed-bed adsorption experiments, isoproturon breakthrough curves onto F400 activated carbon at different initial concentration (50-150 µg.L-1), volumetric flow rate (2.0-3.0 mL.min-1) and mass of adsorbent (0.1-0.3 g) were obtained. The breakthrough curves showed a low slope-profile, indicating a slow mass transport rate due to a high diffusional resistance, probably attributed to the orientation of the molecule in the inner pores and/or to the high microporous nature of the adsorbent. CONCLUSIONS A batch adsorption capacity of 316 mg.g-1 and saturation adsorption capacities from 9.6 to 21.6 mg.g-1 were obtained onto the commercial activated carbon. The hydrophobic nature and low water solubility of isoproturon molecule could enhance the affinity towards the hydrophobic surface of the carbon. The presence of an aromatic ring on its structure contributes to a higher interaction with the carbonaceous surface. ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support from Ministerio de Economía y Competitividad Contract CTM2014-53485-REDC-TRAGUANET, CTQ2014-59011-R REMEWATER and by Comunidad de Madrid through REMTAVARES Network S2013/MAE-2716.
PROCEEDINGS-ARTICLE 6 Reads 0 Citations Catalytic wet air oxidation of caffeine by using a Pt based-catalyst supported on a lignocellulosic activated carbon Silvia Alvarez, Araceli Rodríguez, Gabriel Ovejero, Juan Gar... Published: 16 November 2016
Proceedings of The 1st International Electronic Conference on Water Sciences, doi: 10.3390/ecws-1-c001
DOI See at publisher website ABS Show/hide abstract
Introduction Wastewater usually contains a great variety of hazardous organic compounds, being of special concern the so-called emerging compounds. Among these substances, the priority compounds are considered as especially toxic, showing most of them endocrine disruption effects. The objective of this work was to evaluate the removal of caffeine from water by catalytic wet air oxidation (CWAO), using a Pt based-catalyst supported on a lignocellulosic activated carbon. The effect of the operation conditions, e.g., pressure, temperature and weight of catalyst on the removal of the contaminant and Total Organic Carbon was studied. MATERIALS AND METHODS The tested catalytic support was based on a mesoporous activated carbon synthesized from peach stones by chemical activation using H3PO4 solution. The active phase of the catalyst was platinum with a metallic content of 3%, using H2PtCl6x6H2O as precursor. The metal was incorporated to the support by incipient wetness impregnation. The textural and morphological properties of the catalyst were explored. The tested operation conditions were the total pressure (20-40 bar), temperature (130-170 ºC) and the weight of catalyst (0.1-0.3 g). The sample analysis were carried out by using HPLC technique. RESULTS AND DISCUSSION N2 adsorption-desorption isotherm of the catalyst can be classified as IV-type, characteristic of mesoporous solids. The specific surface area of the catalyst was of 1100 m2.g-1. BET area decreased after the CWAO process until 900 m2.g-1, probably due to the formation of a carbon deposit on the catalyst surface. Referring to the CWAO process, caffeine and TOC concentration gradually decreased along the reaction time, reaching to a final conversion, after 180 min, of 78-94% and 14-72%, respectively and depending on the reaction temperature. CONCLUSIONS The results of the study showed that CWAO of caffeine and TOC in water was successfully carried out using Pt(3%)/activated carbon as catalyst at the tested conditions. This material provides an efficient removal of caffeine, a trace compound of the domestic wastewater pollution. ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support from Ministerio de Economía y Competitividad Contact CTM2014-53485-REDC TRAGUANET, CTQ2014-59011-R REMEWATER and by Comunidad de Madrid through REMTAVARES Network S2013/MAE-2716.
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