Examinando por Autor "Segura, Y."

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Chemically activated hydrochars as catalysts for the treatment of HTC liquor by catalytic wet air oxidation
(Elsevier, 2023) Mora, A. de; Diaz de Tuesta, J.L.; Pariente, M.I.; Segura, Y.; Puyol, D.; Castillo, E.; Lissitsyna, K.; Melero, J.A.; Martínez, F.
Hydrothermal carbonization (HTC) is a highly efficient and valuable technology for treating wet solid wastes and producing solid carbon-based materials named hydrochar. In this work, a hydrochar coming from the HTC of an anaerobic digestion sludge of wastewater treatment plant was used to assess the influence of several activation agents, a base (KOH) and different chloride salts (FeCl3, ZnCl2, and CuCl2) with the exact molar quantities, to develop materials with enhanced surface area and potential inclusion of metal active species for application in wet air oxidation processes. The KOH as an activating agent increased the surface area of hydrochar up to ca. 1000 m2/g of BET surface area. The employment of CuCl2 and FeCl3 as activating agents allows Cu- and Fe-rich doped materials of remarkable surface areas with 49.1 and 42.5 wt% of each metal, respectively. Likewise, the catalytic behavior of the different synthesized carbon-based materials as metal-free and metal-doped catalysts was evaluated for the Catalytic Wet Air Oxidation (CWAO) of a HTC aqueous liquor from a HTC process of animal manure to produce a valuable stream of higher biochemical methane potential in anaerobic digestion. CWAO effluents increased the proportion of carboxylic acids as final by-products due to the oxidation of more complex organic compounds of the initial effluent (ketones, phenols, aromatics and olefins). The CWAO treatments improve the anaerobic digestion rate in biochemical methane potential tests, although the methane production was limited by the lower TOC concentration of the treated streams after CWAO. This research contributes to developing sustainable and efficient strategies for the HTC-liquor treatment, using its solid hydrochar as catalysts, closing the loop of a Circular Economy.
Coupling membrane separation and photocatalytic oxidation processes for the degradation of pharmaceutical pollutants
(Elsevier, 2013) Martínez, F.; López-Muñoz, M.J.; Aguado, J.; Melero, J.A.; Arsuaga, J.; Sotto, A.; Molina, R.; Segura, Y.; Pariente, M.I.; Revilla, A.; Cerro, L.; Carenas, G.
The coupling of membrane separation and photocatalytic oxidation has been studied for the removal of pharmaceutical pollutants. The retention properties of two different membranes (nanofiltration and reverse osmosis) were assessed. Comparable selectivity on the separation of pharmaceuticals were observed for both membranes, obtaining a permeate stream with concentrations of each pharmaceutical below 0.5 mg/L and a rejected flux highly concentrated (in the range of 16-25 mg/L and 18-32 mg/L of each pharmaceutical for NF-90 and BW-30 membranes, respectively), when an initial stream of six pharmaceuticals was feeding to the membrane system (10 mg/L of each pharmaceutical). The abatement of concentrated pharmaceuticals of the rejected stream was evaluated by means of heterogeneous photocatalytic oxidation using TiO2 and Fe2O3/SBA-15 in presence of hydrogen peroxide as photo-Fenton system. Both photocatalytic treatments showed remarkable removals of pharmaceutical compounds, achieving values between 80 and 100 %. The nicotine was the most refractory pollutant of all the studied pharmaceuticals. Photo-Fenton treatment seems to be more effective than TiO2 photocatalysis, as high mineralization degree and increased nicotine removal were attested. This work can be considered an interesting approach of coupling membrane separation and heterogeneous photocatalytic technologies for the successful abatement of pharmaceutical compounds in effluents of wastewater treatment plants.
Enhancement of the Advanced Fenton process (Fe0/H2O2) by ultrasound for the mineralization of Phenol
(ELSEVIER, 2012-02) Segura, Y.; Martínez, F.; Melero, J.M.; Molina, R.; Chand, R; Bremner, D.H.
In this study, a successful mineralization of phenol was achieved by means of coupling zero-valent iron (ZVI) particles, hydrogen peroxide and a short input of ultrasonic irradiation. This short Sono-Advanced Fenton process (AFP) provided a better performance of ZVI in a subsequent silent degradation stage, which involves neither extra cost of energy nor additional oxidant. The short input of ultrasound irradiation enhanced the activity of the Fe0/H2O2 system in terms of the TOC removal. Then, the TOC mineralization continued during the silent stage, even after the total consumption of hydrogen peroxide, reaching values of ca. 90% TOC conversions over 24 hours. This remarkable activity was attributed to the capacity of the ZVI/iron oxide composite formed during the degradation for the generation of oxidizing radical species and to the formation of another reactive oxidant species, such as the ferryl ion. The modification of the initial conditions of the sono-AFP system such as the ultrasonic irradiation time and the hydrogen peroxide dosage, showed significant variations in terms of TOC mineralization for the ongoing silent degradation stage. An appropriate selection of operation conditions will lead to an economical and highly efficient technology with eventual large-scale commercial applications for the degradation organic pollutants in aqueous effluents.