Examinando por Autor "Melero, Juan Antonio"

Mostrando 1 - 14 de 14

Carbonaceous materials from a petrol primary oily sludge: Synthesis and catalytic performance in the wet air oxidation of a spent caustic effluent
(Elsevier, 2024-08) Jerez, Sara; Ventura, María; Martínez, Fernando; Pariente, María Isabel; Melero, Juan Antonio
Oil refineries produce annually large quantities of oily sludge and non-biodegradable wastewater during petroleum refining that require adequate management to minimize its environmental impact. The fraction solid of the oily sludge accounts for 25 wt% and without treatment for their valorization. This work is focused on the valorization of these solid particles through their transformation into porous materials with enhanced properties and with potential application in the catalytic wet air oxidation (CWAO) of a non-biodegradable spent caustic refinery wastewater. Hence, dealing with the valorization and treatment of both refinery wastes in a circular approach aligned with the petrol refinery transformations by 2050. The obtained oily sludge carbonaceous materials showed improved surface area (260–762 m2/g) and a high Fe content. The good catalytic performance of these materials in CWAO processes has been attributed to the simultaneous presence of surface basic sites and iron species. Those materials with higher content of Fe and basic sites yielded the highest degradation of organic compounds present in the spent caustic refinery wastewater. In particular, the best-performing material ACT-NP 1.1 (non-preoxidated and thermically treated with 1:1 mass ratio KOH:solid) showed a chemical oxygen demand (COD) removal of 60 % after 3 h of reaction and with a higher degradation rate than that achieved with thermal oxidation without catalyst (WAO) and that using an iron-free commercial activated carbon. Moreover, the biodegradability of the treated wastewater increased up to 80% (from ca. 31% initially of the untreated effluent). Finally, this material was reused up to three catalytic cycles without losing metal species and keeping the catalytic performance
Contamination of N-poor wastewater with emerging pollutants does not affect the performance of purple phototrophic bacteria and the subsequent resource recovery potential
(2020) Martínez, Fernando; de las Heras, Igor; Molina, Raúl; Segura, Yolanda; Hülsen, Tim; Molina, María Carmen; Gonzalez-Benítez, Natalia; Melero, Juan Antonio; Mohedano, Ángel F.; Puyol, Daniel
Propagation of emerging pollutants (EPs) in wastewater treatment plants has become a warning sign, especially for novel resource-recovery concepts. The fate of EPs on purple phototrophic bacteria (PPB)-based systems has not yet been determined. This work analyzes the performance of a photo-anaerobic membrane bioreactor treating a low-N wastewater contaminated with 25 EPs. The chemical oxygen demand (COD), N and P removal efficiencies were stable (76 ± 8, 62 ± 15 and 36 ± 8 %, respectively) for EPs loading rate ranging from 50 to 200 ng L-1 d-1. The PPB community adapted to changes in both the EPs concentration and the organic loading rate (OLR) and maintained dominance with >85 % of total 16S gene copies. Indeed, an increment of the OLR caused an increase of the biomass growth and activity concomitantly with a higher EPs removal efficiency (30 ± 13 vs 54 ± 11 % removal for OLR of 307 ± 4 and 590 ± 8 mgCOD L-1 d-1, respectively). Biodegradation is the main mechanism of EPs removal due to low EPs accumulation on the biomass, the membrane or the reactor walls. Low EPs adsorption avoided biomass contamination, resulting in no effect on its biological methane potential. These results support the use of PPB technologies for resource recovery with low EPs contamination of the products.
Degradation of phenolic aqueous solutions by high frequency sono-fenton systems (US-Fe2O3/SBA-15-H2O2)
(Elsevier, 2009) Bremner, David H.; Molina, Raúl; Martínez, Fernando; Melero, Juan Antonio; Segura, Yolanda
The aim of this work is to establish the influence of different ultrasonic frequencies ranging from 20 to 1142 kHz on the efficiency of the US/Fe2O3/SBA-15/H2O2 (sono-Fenton) system. The frequency of 584 kHz has been established as the optimum ultrasonic irradiation for the degradation of aqueous phenol solutions by the sono-Fenton system and the effect of different variables, such as hydrogen peroxide concentration or catalyst loadings in the reaction was studied by factorial design of experiments. Catalyst loadings of 0.6 g/L and hydrogen peroxide concentration, close to the stoichiometric amount, show high organic mineralization, accompanied by excellent catalyst stability in a wide range of concentrations of aqueous phenol solutions (0.625 to 10 mM). Additionally, the catalyst can be easily recovered by filtration for reuse in subsequent reactions without appreciable loss of activity. The coupling of US (584 kHz)/Fe-SBA-15/H2O2 at room temperature is revealed as a promising technique for wastewater treatment. Additionally, a new sono-Fenton variant, the so-called latent remediation has also been studied, using ultrasonic irradiation only as pretreatment for 15 minutes in an attempt at reducing the cost of the degradation process. It has been observed that latent remediation provides TOC degradation of around 21 % after 15 min sonication followed by 6 h silent reaction while the typical sono-Fenton reaction affords 29 % TOC reduction after 6h sonication. Keywords: Ultrasound, Sono-Fenton; Phenol; SBA-15.
Effective pharmaceutical wastewater degradation by Fenton oxidation with zero-valent iron
(Elsevier, 2013) Segura, Yolanda; Martínez, Fernando; Melero, Juan Antonio
The pre-treatment of a pharmaceutical wastewater (PWW) by Fenton Oxidation with zero-valent iron (ZVI) and hydrogen peroxide was investigated to improve the degradation of the complex-mixture of organic compounds present in the wastewater. The influence of different crucial parameters such as the initial hydrogen peroxide concentration, the ZVI concentration and the capacity of the ZVI/H2O2 system to treat different organic loading have been evaluated. The optimal conditions for degradation led to TOC reductions of up to 80% in only one hour of treatment. This degree of organic mineralization was reached by using moderate loadings of ZVI and hydrogen peroxide (ZVI/TOC weight and H2O2/TOC molar ratios of 12 and 3.2, respectively). Moreover, the use of waste-metallic iron shavings in terms of TOC removal compared to commercial ZVI powder may be a promising and cheaper development.
Environmental life cycle assessment of polyhydroxyalkanoates production by purple phototrophic bacteria mixed cultures
(Elsevier, 2023) Martin-Gamboa, Mario; Allegue, Luis D.; Puyol, Daniel; Melero, Juan Antonio; Dufour, Javier
Bioplastics offer a promising sustainable alternative to petroleum-based plastics due to their biodegradability as well as favourable thermal and mechanical properties. Among different types of biobased polymers, the production of polyhydroxyalkanoates (PHA) using purple phototrophic bacteria (PPB) and low-value substrates has gained increasing interest. Despite the momentum, challenges regarding the scalability and environmental feasibility of this biopolymer production pathway remain. In response, this study employs an exploratory LCA approach to quantitatively assesses the potential environmental implications of PHA production in powder form and the joint management of the organic fraction of municipal solid waste (OFMSW) through a novel photobiorefinery system that uses PPB mixed cultures. Environmental impacts were tested under multiple improvement scenarios and benchmarked against the production of conventional fossil-based granulate or unprocessed plastics, including low density polyethylene (LDPE), polyethylene terephthalate (PET) and polyurethane (PU). The photobiorefinery stage was found to have the greatest contribution to the impact categories, particularly due to direct emissions, consumption of electricity and production of extractive chemical agents used. These factors accounted for over 70% of the photobiorefinery impact in all cases. Avoided impacts provided net favourable outcomes in terms of carbon footprint and fossil resources when comparing PHA production to conventional plastics, especially PET and PU, with impact reductions ranging from 30% to 60%, respectively. However, when considering other impact categories like eutrophication, this situation was less favourable. The exploration of alternative scenarios offered significant impact reductions, especially when renewable electricity or an environmentally friendly extraction agent is used. Moreover, minimizing methane losses or co-producing hydrogen in the photobiorefinery had a notably positive effect on the carbon footprint, reducing the impact by more than 2 t of CO2 eq per t of PHA powder compared to the base case. Therefore, the implementation of feasible improvement measures in the short term can position PHA produced by mixed cultures as a sustainable alternative to petroleum-based plastics.
Etherification of benzyl alcohols with 1-hexanol over organosulfonic acid mesostructured materials
(ELSEVIER, 2006) van Grieken, Rafael; Melero, Juan Antonio; Morales, Gabriel
Etherification of benzyl alcohols with 1-hexanol was performed in liquid phase over propyl- and arene-SO3H modified mesostructured SBA-15 silica. H2O TPD measurements indicate a stronger interaction of arenesulfonic acid sites with water molecules than that occurring in propylsulfonic groups. Hence, the higher catalytic activity of propylsulfonic modified SBA-15 material is related to the more hydrophobic microenvironment of -SO3H sites which reduces the acid site deactivation associated with adsorption of water generated during the reaction. Moreover, propyl- and arene-sulfonic functionalized SBA-15 material show a clear improvement of the catalytic performances as compared to other commercial homogeneous and heterogeneous acid catalysts in this particular reaction.
Exploring the effects of ZVI addition on resource recovery in the anaerobic digestion process
(2018) Puyol, Daniel; Flores Alsina, Xavier; Segura, Yolanda; Molina, Raúl; Padrino, Beatriz; Fierro, Jose Luis G.; Gernaey, Krist V.; Melero, Juan Antonio; Martínez, Fernando
The influence of Zero Valent Iron (ZVI) addition on the potential resource recovery during the anaerobic digestion (AD) of domestic waste sludge is assessed. Potentially recoverable resources analyzed were nutrients such as struvite to recover P, and energy as biogas to recover C. Short term (biochemical methane potential tests, BMP) and long term (AD1, AD2) experiments are conducted using two types of set-up (batch, continuous). Process data (influent, effluent and biogas) is continuously collected and the dry digested sludge is analyzed by XPS. A mathematical model is developed based on a modified version of the Anaerobic Digestion Model No 1 upgraded with an improved physicochemical description, ZVI corrosion, propionate uptake enhancement and multiple mineral precipitation. The results of all experiments show that ZVI addition increases methane production and promotes the formation of siderite (FeCO3) and vivianite (Fe3(PO4)2), which causes changes in the biogas composition (%CH4 versus %CO2) and reduces P release. The model can satisfactorily reproduce the dynamics of AD processes, nutrient release, pH and methanogenesis in AD1. The proposed approach also describes the changes in the overall performance of the process because of ZVI addition in AD2. A model-based scenario analysis is included balancing chemical-ZVI addition and increased methane production/struvite precipitation. This scenario analysis allows concluding that: (a) the improvement of methane production does not compensate the costs of ZVI purchase, and (b) ZVI dramatically decreases the P recovery potential in the digestate of the AD systems. This is the first study to experimentally and mathematically describe the effect of ZVI on biogas production/composition and on the fate of phosphorus compounds, and its potential implications for potential energy and phosphorus recovery in AD systems.
Heterogeneous Photo-Fenton Oxidation of Benzoic Acid in Water Effect of Operating Conditions, Reaction By-Products and Coupling with Biological Treatment
(ELSEVIER, 2008) Pariente, M. Isabel; Martínez, Fernando; Melero, Juan Antonio; Botas, Juan Ángel; Velegraki, Theodora; Xekoukoulotakis, Nikolaos P.; Mantzavinos, Dionissios
The heterogeneous photo-Fenton oxidation of benzoic acid, a precursor of several organic pollutants found in agro-industrial effluents, was studied in model aqueous solutions. UVA irradiation was provided by a 125 W medium pressure mercury lamp, while a nanocomposite material of crystalline iron oxides supported over mesostructured SBA-15 was used as the catalyst. Experiments were conducted at benzoic acid initial concentrations between 25 and 450 mg/L, catalyst concentrations between 0.3 and 1.2 g/L and hydrogen peroxide concentrations between 20% and 100% of the stoichiometric amount needed for complete mineralization. Conversion, which was found to be first order regarding benzoic acid concentration, generally increased with increasing the concentration of Fenton¿s reagents and decreasing substrate concentration. HPLC analysis showed that oxidation was accompanied by the formation of several by-products; of these, the three monohydroxybenzoic acids as well as oxalic acid were successfully identified and quantified. By-products were more resistant to oxidation than benzoic acid since COD reduction was generally lower than substrate conversion. Catalyst stability was assessed measuring the extent of iron leaching in the reaction mixture and was found to be excellent as dissolved iron never exceeded 5% relative to the initial iron content. The aerobic biodegradability of benzoic acid before and after photo-Fenton oxidation was assessed by shake flask tests. Chemical oxidation enhanced the biodegradability of benzoic acid although the oxidized solution was more ecotoxic to marine bacteria than the original one. The feasibility of coupling chemical and biological oxidation was also assessed for an actual olive oil mill effluent.
Increasing biodegradability of a real amine-contaminated spent caustic problematic stream through WAO and CWAO oxidation using a high specific surface catalyst from petcoke
(Elsevier, 2023) González, Carlos; Pariente, María Isabel; Molina, Raúl; Espina, L.G.; Masa, María; Bernal, Vicente; Melero, Juan Antonio; Martinez, Fernando
Different operating conditions of wet air oxidation and catalytic wet air oxidation have been studied for the treatment of highly concentrated methyldiethanolamine wastewater streams from amine units of acid gas recovery in petrol refineries. These units occasionally generate streams of high methyldiethanolamine content that require special actions to avoid undesirable impacts on the downstream biological process of the petrochemical wastewater treatment plant due to its inhibition effect. The wet air oxidation treatment achieved remarkable removals of methyldiethanolamine, sulfides, chemical oxygen demand and total organic carbon (99%, 95%, 65% and 38%, respectively). Likewise, activated petroleum coke materials from the own refinery plant were tested as catalysts in the process. These materials were prepared under different conditions (chemical activating agent and thermal carbonization process). The catalytic wet air oxidation treatment using an activated petroleum coke was able to remove the methyldiethanolamine at milder operation conditions keeping a similar performance in terms of wastewater treatment removals as compared to the non-catalytic experiments. This technology significantly increased the biodegradability of the treated effluents ranging from 25 to 70 % due to the formation of more biodegradable substrates (acetic acid and ammonium) for further biological treatment.
Liquid phase rearrangement of long straight-chain epoxides over amorphous, mesostructured and zeolitic catalysts
(ELSEVIER, 2004) Serrano, David P.; van Grieken, Rafael; Melero, Juan Antonio; García, Alicia
A variety of materials with different structural features and acid properties, including amorphous, mesostructured and zeolitic catalysts have been tested in the liquid-phase rearrangement of 1,2-epoxyoctane. The structure and acid strength of the catalysts influence strongly on the activity and product selectivity. The main rearrangement products are the aldehyde, allylic alcohols and diol. Acid sites in the amorphous materials show a poor catalytic activity. Al-TS-1 and Al-Ti-beta, zeolites with medium aluminium content, lead to significant activities and selectivities towards both the aldehyde and the octenols in comparison to those obtained with other zeolitic materials tested. Aluminium-containing mesostructured materials present much higher activities than amorphous and zeolitic catalysts. Al-MCM-41 synthesized by a sol-gel method at room temperature yielded selectivities to octaldehyde and octen-1ols of 40.6% and 44.7%, respectively with a high catalyst activity (TOF of ca. 30.5).
Mineralization of phenol by a heterogeneous ultrasound\Fe-SBA-15\H2O2 process: multivariate study by factorial design of experiments
(Elsevier, 2006) Molina, Raúl; Martínez, Fernando; Melero, Juan Antonio; Bremner, David H.; Chakinala, Anand G.
A novel heterogeneous catalyst has been used for the oxidation of aqueous solutions of phenol by catalytic wet peroxide oxidation assisted by ultrasound irradiation. This composite catalyst material that contains crystalline hematite particles embedded into a mesostructured SBA-15 matrix was used successfully in the oxidation of phenol by heterogeneous Fenton and photo-Fenton processes. Ultrasound is found to enhance the activity of the catalyst in the process, without prejudice to the stability of the iron supported species. The influence of different variables, such as hydrogen peroxide concentration or catalyst loadings in the reaction was studied by factorial design of experiments. Catalyst loadings of 0.6 g/L and a concentration of hydrogen peroxide close to twice the stoichiometric amount yield a remarkable organic mineralization, accompanied by excellent catalyst stability. The coupled US/Fe-SBA-15/H2O2 process at room temperature is revealed as a promising technique for wastewater treatment.
Production of Sorbitol via Catalytic Transfer Hydrogenation of Glucose
(MDPI, 2020-03-07) García, Beatriz; Moreno, Jovita; Morales, Gabriel; Melero, Juan Antonio; Iglesias, Jose
Sorbitol production from glucose was studied through catalytic transfer hydrogenation (CTH) over Raney nickel catalysts in alcohol media, used as solvents and hydrogen donors. It was found that alcohol sugars, sorbitol and mannitol, can be derived from two hydrogen transfer pathways, one produced involving the sacrificing alcohol as a hydrogen donor, and a second one involving glucose disproportionation. Comparison between short-chain alcohols evidenced that ethanol was able to reduce glucose in the presence of Raney nickel under neutral conditions. Side reactions include fructose and mannose production via glucose isomerization, which occur even in the absence of the catalyst. Blank reaction tests allowed evaluating the extension of the isomerization pathway. The influence of several operation parameters, like the temperature or the catalyst loading, as well as the use of metal promoters (Mo and Fe-Cr) over Raney nickel, was examined. This strategy opens new possibilities for the sustainable production of sugar alcohols.
Ru-ZrO2-SBA-15 as efficient and robust catalyst for the aqueous phase hydrogenation of glucose to sorbitol
(2020-02-05) Melero, Juan Antonio; Moreno, Jovita; Iglesias, Jose; Morales, Gabriel; Fierro, Jose Luis García; Sánchez Vázquez, Rebeca; Cubo, A.; García, Beatriz
The hydrogenation of aqueous solutions of glucose into sorbitol has been tackled in the presence of rutheniumfunctionalized catalysts using mesostructured pure-silica SBA-15 and ZrO2-coated SBA-15 materials as supports. The influence of the metal loading and the presence of ZrO2 in the supports on the catalytic activity of these materials have been evaluated. Metal loading is a major factor affecting the dispersion of the ruthenium active phase, but the presence of a zirconia layer onto the catalyst support revealed to be a key parameter to control not only the dispersion of Ru particles, but also their stability. Catalysts characterization and reaction tests to evaluate the catalytic performance of Ru-containing materials evidenced the beneficial influence of ZrO2-containing supports to prevent the agglomeration of Ru nanoparticles during hydrogenation tests, thus leading to more robust catalysts. This work proposes an approach to the preparation of active and stable catalysts for aqueous phase hydrogenation of biomass-derived carbohydrates.
Transformation of Glucose into Sorbitol on Raney Nickel Catalysts in the Absence of Molecular Hydrogen: Sugar Disproportionation vs Catalytic Hydrogen Transfer
(2019-03-01) García, Beatriz; Moreno, Jovita; Iglesias, Jose; Melero, Juan Antonio; Morales, Gabriel
Raney nickel catalysts have been tested in the transformation of glucose into sorbitol through a hydrogen transfer pathway in the presence of short chain alcohols. Comparison between different sacrificing alcohols evidenced that catalytic hydrogen transfer (CHT) was only possible from ethanol under the tested neutral conditions. Catalytic tests showed that together with CHT route, sorbitol was also produced by means of sugar disproportionation, with the simultaneous production of gluconolactone, which takes place easily in the presence of the Raney Ni catalysts. Studies on the influence of the catalyst loading on the production of sorbitol revealed the existence of a catalyst activation step, attributed to the generation of metal-hydride species, the truly catalytic sites for hydrogenation. However, a catalyst deactivation phenomenon was detected as well. In this case, TGA and FTIR analysis allowed ascribing the adsorption of organic species, coming from the oxidation of glucose (such as gluconic acid), onto the catalyst surface, to the most plausible cause for the deactivation of the catalyst. Catalyst recycling tests evidenced the deactivation occurred mainly during the first use of the Raney Ni catalyst.