Examinando por Autor "Martínez, Fernando"

Mostrando 1 - 20 de 26

A double basic Sr-amino containing MOF as a highly stable heterogeneous catalyst
(Royal Society of Chemistry, 2019-07-03) Leo, Pedro; Orcajo, Gisela; Briones, David; Rodríguez-Dieguez, Antonio; Choquesillo-Lazarte, Duane; Calleja, Guillermo; Martínez, Fernando
A novel metal–organic framework (MOF) based on strontium alkaline-earth metal and 2-amino-1,4-benzenedicarboxylic acid (NH2-bdc) has been developed. This material is formed by a linear succession of face-sharing strontium polyhedra bridged by an organic ligand molecule to give a three-dimensional network with rhombohedral one-directional channels. This MOF is stable in polar organic solvents and up to 250 °C. The basic catalytic activity of both strontium metal nodes and amino groups of the ligand was tested in Knoevenagel condensation reactions. The influence of the temperature and reaction solvent over the catalytic performance of the MOF catalyst was demonstrated. The strontium/amino-containing MOF material evidenced a remarkable activity as compared to other conventional alkaline oxides typically used as reference basic solid catalysts. The novel MOF material showed remarkable activity and structural stability during five consecutive catalytic runs with no evidence of activity loss under the best reaction conditions found in this study.
A novel photoanaerobic process as a feasible alternative to the traditional aerobic treatment of refinery wastewater
(Elsevier, 2022) San Martín, Javier; Puyol, Daniel; Segura, Yolanda; Melero, Juan A.; Martínez, Fernando
Refinery wastewater (RWW) treatment is outdated since new wastewater management and reuse challenges require more environmental-friendly and cheap alternatives. Conventional biological treatments focused on activated sludge are highly energy-intensive and resource-dissipating processes. However, anaerobic treatments are an excellent alternative to reduce costs derived from aeration and carbon footprint. This work proposes a novel strategy for the treatment of RWW involving a photoanaerobic membrane bioreactor (PAnMBR) with a mixed culture of purple phototrophic bacteria (PPB). PPB upcycles the organic matter, nitrogen, and phosphorus in an assimilative way, leading to a much higher biomass yield and nutrient removal than aerobic cultures. The enriched PPB culture was generated from the RWW as the sole substrate without specific PPB inoculation. The RWW (exempted from sufficient nutrients) was successfully treated with additional ammonium and phosphates provided by domestic wastewater (DWW). Preliminary batch tests determined the best DWW/RWW volumetric mixing ratio at 25:75. The PAnMBR was operated for 144 days under different specific loading rates (SLR) by modifying hydraulic and solid retention times. The maximum specific loading rate (SLR) for the efficient RWW/ DWW mix treatment was 0.3 mgCODinlet/mgCODbiomass⋅d. The COD consumption was mainly mediated by Rhodopseudomonas sp. and Rhodobacter sp. PPB genera. The PPB-based photo-anaerobic membrane reactor was able to comply with regulated parameters for wastewater discharge for the more restrictive use of reclaimed water according to the European legislation in force.
Application of a Fenton process for the pretreatment of an iron-containing oily sludge: A sustainable management for refinery wastes
(Elsevier, 2021-12-03) Jerez, Sara; Ventura, Maria; Molina, Raul; Martínez, Fernando; Pariente, Maria Isabel; Melero, Juan Antonio
The feasibility of a Fenton-type process for the pretreatment of an oily refinery sludge has been explored taking advantage of the iron contained in the own sludge. This process reduces the content of total petroleum hydro-carbons (TPHs) accompanied by an increase in the total organic carbon concentration in the liquid phase. The effect of the temperature and the hydrogen peroxide loading was thoroughly studied in this work being the oxidant concentration the most critical parameter. Under 60 ◦C and 90 g/L of initial hydrogen peroxide concentration, the Total Organic Carbon (TOC) of the liquid phase was increased up values of 1336 mg/L and with a remarkable contribution of acetic acid as final oxidized compound (396 mgC/L). Additionally, nitrogen and phosphorous compounds were also dissolved in the aqueous phase achieving values of 250 mg/L and 7 mg/L for total Kjeldahl nitrogen and total phosphorous, respectively. Respirometry assays of the aqueous phase after the Fenton pretreatment have evidenced an increase of biodegradability up to 49% which makes this phase suitable for further biological processing in the refinery scheme. The reduction of the content of TPHs (61%) of the oily sludge, has also improved the settleability of the treated effluent (reducing the capillary suction time (CST) in ca. 88%).
Biodiesel and biogas production from Isochrysis galbana using dry and wet lipid extraction: A biorefinery approach
(Elsevier, 2020) Sánchez-Bayo, Alejandra; López-Chicharro, Daniel; Morales, Victoria; Espada, Juan José; Puyol, Daniel; Martínez, Fernando; Astals, Sergi; Vicente, Gemma; Bautista, Luis Fernando; Rodríguez, Rosalía
Wet lipid extraction combined with residual biomass anaerobic digestion are alternatives to reduce the overall energy consumption of biodiesel production from microalgae. Solvents with different polarities have been studied to assess dry and wet lipid extraction process from Isochrysis galbana microalga. Ethyl acetate (EA) and a chloroform:methanol (CM) mixture yielded the best lipid extraction results in the dry and wet route with suitable lipid compositions. Fatty acid methyl esters (FAMEs) conversion of dry and wet extracted lipids with these solvents was performed by using both homogeneous (H2SO4) and heterogeneous (resin CT 269) catalysts. FAME production from wet extracted lipids with the EA solvent using the CT-269 resin constitutes an advantageous process because it avoids the water elimination step, and the CT-269 is a heterogeneous commercial catalyst, readily to separate after reaction. Lipid-spent microalga was anaerobically digested, obtaining that waste biomass from the wet extraction with EA had the highest methane yield (310 mL CH4/g volatile solids (VS). Energy balance analysis for FAMEs production with EA solvent (wet route) and heterogeneous catalyst yielded an energy recovery of about 80% in terms of biodiesel and biogas. Therefore, this process constitutes a promising route under an energy-driven microalga biorefinery.
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
Catalytic activity and stability of sulfonic-functionalized UiO-66 and MIL-101 materials in friedel-crafts acylation reaction
(Elsevier, 2022-05-01) Leo, Pedro; Crespí, Neus; Palomino, Carlos; Martín, Antonio; Orcajo, Gisela; Calleja, Guillermo; Martínez, Fernando
Sulfonic-containing UiO-66 and MIL-101 MOF materials, prepared by direct synthesis with a sulfonic acid-including benzene dicarboxylate (SO3H-BDC) linker, have been evaluated as acid catalysts in Friedel–Crafts acylation of anisole with acetic anhydride. The catalytic activity of these materials was compared to other conventional acidic sulfonic heterogeneous catalysts, such as commercial Nafion-SAC-13 and Amberlyst-15. The catalytic performance of MOF materials was significantly dependent on their textural properties and the availability of sulphonic acid groups. MIL-101-SO3H material displayed a remarkable anisole conversion and specific activity per sulfonic acid centre due to its open structure and multimodal pore size distribution. The inherent properties of MIL-101-SO3H material allowed a more sustainable catalyst regeneration than those used for conventional heterogeneous catalysts due to the deposition of reagents and products, in particular poly-acetylated compounds. MIL-101-SO3H proved an easy recovery and reusability in successive runs without any loss of activity. These promising results evidenced the potential of MIL-101-SO3H as an alternative catalyst for acid-catalyzed reactions.
Catalytic Advantages of SO3H-Modified UiO-66(Zr) Materials Obtained via Microwave Synthesis in Friedel–Crafts Acylation Reaction
(American Chemical Society, 2024-09-03) Bauza, Marta; Leo, Pedro; Palomino Cabello, Carlos; Martín, Antonio; Orcajo, Gisela; Turnes Palomino, Gemma; Martínez, Fernando
The catalytic activity and stability of sulfonic-based UiO-66(Zr) materials were tested in the Friedel–Crafts acylation of anisole with acetic anhydride. The materials were prepared using microwave-assisted synthesis, producing microporous materials with remarkable crystallinity and physicochemical features as acid catalysts. Different ratios between both organic ligands, terephthalic acid (H2BDC) and monosodium 2-sulfoterephthalic acid (H2BDC–SO3Na), were used for the synthesis to modulate the sulfonic content. The sulfonic-based UiO-66(Zr) material synthesized with a H2BDC/H2BDC–SO3Na molar ratio of 40/60 exhibited the best catalytic performance in the acidic-catalyzed Friedel–Crafts acylation reaction. This ratio balanced the number of sulfonic acid sites and their accessibility within the UiO-66 microporous structure. The catalytic performance of this material increased remarkably at 200 °C, outperforming reference acids and commercial heterogeneous catalysts such as Nafion-SAC-13 and Amberlyst-70. Additionally, the best sulfonic-based UiO-66(Zr) material proved to be stable in four successive reaction cycles, maintaining both its catalytic activity and its structural integrity
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.
Development of an interactive online tool to improve the teaching-learning experience in experimental laboratories
(2022-07) Molina, Raúl; Paredes, Beatriz; García, Alicia; Martín-Rengel, Antonio; Martínez, Fernando
The FLUID-LABVIR platform (https://www.gid-simip.com/en/virtual-laboratory/) is an attempt to innovate in the experience of students who must carry out laboratory demonstrations, particularly in engineering and fluid mechanics subjects. This platform provides students with a tool (guide prepared as a website) adapted to the context of current electronic media, in a multi-platform web format (PC, mobile, tablet) in an iterative mode. This electronic platform will be able to provide the theoretical fundamentals and measurements for the performance of the demonstration practice, but also images, animations (to support fundamentals) and/or videos explaining the handling of the demonstration practice by specialized professors. This platform offers the opportunity to evaluate the influence of different operation conditions through an immersive simulator that reproduce the experimental installation and the handling devices that the students manipulate in the real demonstration practice in the lab. This platform would also give the opportunity to develop in the same virtual mode other demonstration activities that are not performed in the lab in those experimental set-ups for the limited schedule time of the demonstration practices. On the platform website, students can download or access the practice simulator via the MyApps platform of Rey Juan Carlos University. This simulator is accompanied by a short tutorial video showing how to use the simulator and the operation that they can virtually do to get measurements for application to their calculations. Currently, this electronic platform and simulator has been implemented for three demonstration practices: Head Drop in Pipes, Flow in Open Channel and Wind Tunnel.
Direct α-arylation of ketones efficiently catalyzed by Cu-MOF-74
(Elsevier, 2019-09-19) Leo, Pedro; Orcajo, Gisela; Briones, David; Martínez, Fernando; Calleja, Guillermo
The activity and reusability of Cu-MOF-74 as heterogeneous catalyst were studied in the Cu-catalyzed CeC crosscoupling reaction of 4-iodotoluene (4-IT) with acetylacetone (AcAc) to direct synthesis of α-aryl-ketones. CuMOF-74 is characterized by having unsaturated copper sites into its highly porous metal-organic framework that can play a crucial role in catalytic applications. The influence of critical reaction variables such as solvent, reaction temperature, AcAc/4-IT ratio, catalyst concentration and basic agent (type and concentration) were evaluated. High conversions were achieved at 140°C, 5mol % of catalyst, AcAc/4-IT ratio of 2:1, DMF as solvent and 1.5 equivalent of Cs2CO3 base. The C-arylation between 4-IT and AcAc proceeded only in the presence of CuMOF-74 material, being very low the transformation in absence of the solid catalyst. Cu-MOF-74 material displayed a remarkable structural stability, regarding its XRD patterns and solid recovery degree after several reaction cycles, which was also complemented by the negligible amount of copper leached in the reaction media. This catalyst showed promising results in comparison to other homogeneous and heterogeneous Cu-based catalysts. This work evidences the great potential of MOF materials as heterogeneous catalysts in fine chemistry applications.
Diseño de actividades con laboratorios virtuales para fomentar el trabajo autónomo y la adquisición de competencias relacionadas con prácticas de laboratorio experimentales
(2023-11) Cruz del Álamo, Ana; Megía, Pedro; Plaza, Jorge; Casado, Cintia; García, Alicia; Martín, Antonio; Paredes, Beatriz; Villajos, Beatriz; San Martín, Javier; Morales, Gabriel; van Grieken, Rafael; Martínez, Fernando; Molina, Raúl
En este trabajo se muestra el desarrollo de diferentes actividades realizadas con una plataforma online de laboratorios virtuales diseñada por profesores del Departamento de Tecnología Química y Ambiental de la Universidad Rey Juan Carlos. La plataforma incluye 4 prácticas, con una página web para cada una de ellas con diferentes contenidos audiovisuales, entre los que cabe destacar un video del manejo de la instalación experimental y un simulador que reproduce el funcionamiento de la práctica experimental. Durante tres cursos académicos (de 2020/21 a 2022/23), la plataforma se ha utilizado en las asignaturas de Ingeniería de Fluidos y Mecánica de Fluidos de varios grados de la Universidad Rey Juan Carlos como material de apoyo para la realización de las prácticas, como herramienta para complementar las practicas experimentales con actividades adicionales en modo online a través del uso de simuladores virtuales de las prácticas, o como guía para la realización de las prácticas y sistema de evaluación individual. Los estudiantes consideran que la plataforma es un buen complemento para la preparación de las prácticas, mejorando la experiencia posterior en el laboratorio experimental, opinión que es compartida también por los profesores responsables.
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.
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.
Fenton-like catalyst based on a reticulated porous perovskite material: Activity and stability for the on-site removal of pharmaceutical micropollutans in a hospital wastewater
(Elsevier, 2020) Martínez, Fernando; Cruz del Álamo, Ana; González, Carlos; Pariente, María Isabel; Molina, Raúl
Powdered LaCu0.5Mn0.5O3 perovskite was successfully conformed in a reticulated macroporous structure to be tested in an up-flow catalytic packed bed reactor as on-site pre-treatment of pharmaceutical micropollutants in a hospital wastewater. Initially, the effect of the pH, the temperature and the hydrogen peroxide were studied using the hospital wastewater fortified with carbamazepine (CZP) in order to determine the best operation conditions. The reticulated porous perovskite catalyst evidenced a remarkable activity and stability for 70 h on continuous operation in a catalytic packed bed reactor operated at initial pH of ca. 5.5, 70 °C and moderate dosage of hydrogen peroxide (700 mg/L). Under these conditions, the heterogeneous Fenton-like catalytic system achieved an effective removal of pharmaceutical micropollutants of the hospital wastewater in the real range of μg/L, such as antineoplastic drugs, antibiotics, X-ray contrast agent, etc. Most of them were eliminated with removal degrees above 90–95%, being their remaining concentration below the predicted non-effect concentration (PNEC) for aquatic organisms.
Gamificación de los seminarios de mecánica de fluidos computacional en aula de informática mediante Genially
(2024-07) Molina, Raúl; Gómez-Pozuelo, Gema; Casado, Cintia; Paredes, Beatriz; Martínez, Fernando
En este trabajo, se muestra la gamificación del seminario de Mecánica de Fluidos Computacional (CFD) en aula de informática con el objetivo de aumentar la motivación del alumnado y simplificar al aprendizaje de las herramientas CFD. Para ello, se ha dividido en dos partes: i) trabajo autónomo de los estudiantes, para lo que se les suministran video-tutoriales de los casos a simular con CFD, con el manejo específico del software y el tratamiento de datos necesario; y ii) trabajo en grupo en el aula de informática, donde, en un entorno de videojuego, el grupo toma el rol de un avatar que debe resolver retos relacionados con el caso simulado y desbloquear recompensas (elemento motivador y parte de la calificación), hasta llegar al final del juego. Con esta gamificación se pretende potenciar trabajo en equipo en el aula mediante la resolución de los retos planteados a partir de los casos estudiados.
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.
Hf/porphyrin-based metal-organic framework PCN-224 for CO2 cycloaddition with epoxides
(Elsevier, 2023) Carrasco, Sergio; Orcajo, Gisela; Martínez, Fernando; Imaz, Inhar; Kavak, Safiyye; Arenas-Esteban, Daniel; Maspoch, Daniel; Bals, Sara; Calleja, Guillermo; Horcajada, Patricia
Herein, we describe for the first time the synthesis of the highly porous Hf-tetracarboxylate porphyrinbased metal-organic framework (MOF) (Hf)PCN-224(M) (M ¼ H2, Co2þ). (Hf)PCN-224(H2) was easily and efficiently prepared following a simple microwave-assisted procedure with good yields (56e67%; spacetime yields: 1100e1270 kg m3 $day1 ), high crystallinity and phase purity by using trifluoromethanesulfonic acid and benzoic acid as modulators in less than 30 min. By simply introducing a preliminary step (10 min), 5,10,15,20-(tetra-4-carboxyphenyl)porphyrin linker (TCPP) was quantitatively metalated with Co2þ without additional purification and/or time consuming protection/deprotection steps to further obtain (Hf)PCN-224(Co). (Hf)PCN-224(Co) was then tested as catalyst in CO2 cycloaddition reaction with different epoxides to yield cyclic carbonates, showing the best catalytic performance described to date compared to other PCNs, under mild conditions (1 bar CO2, room temperature, 18 e24 h). Twelve epoxides were tested, obtaining from moderate to excellent conversions (35e96%). Moreover, this reaction was gram scaled-up (x50) without significant loss of yield to cyclic carbonates. (Hf)PCN-224(Co) maintained its integrity and crystallinity even after 8 consecutive runs, and poisoning was efficiently reverted by a simple thermal treatment (175 C, 6 h), fully recovering the initial catalytic activity.
MgO-based catalysts for selective delignification of lignocellulosic waste and carboxylic acids production under mild hydrothermal conditions
(Elsevier, 2025-08) Vidal, Nora; Ventura, María; Orfila, María; Martínez, Fernando; Melero, Juan Antonio
Lignocellulosic biomass offers a sustainable alternative to traditional raw materials. However, its complex structure, and particularly the presence of lignin, presents a significant challenge for its conversion into valuable products. This study explores the catalytic performance of magnesium oxide (MgO) based materials for the selective delignification of lignocellulosic waste and concomitant carboxylic acids production. Different MgO samples have been synthesized through various synthetical methods with the purpose of promoting the selective delignification of a lignocellulose waste while minimizing the degradation of other polymers (cellulose and hemicellulose). The resultant lignin-free holocellulose solid after selective depolymerization might be used in subsequent fermentation processes. The catalytic results demonstrated that MgO synthesized by a sol-gel method exhibited the highest catalytic activity, achieving ca. 90 % lignin conversion with minimal degradation of cellulose and hemicellulose and outstanding production of carboxylic acids (ca. 30 % of the carbon of the degraded polymers was converted into carboxylic acids). The high concentration of medium-strength base sites combined with significant macroporosity are crucial for enhancing the catalytic performance of MgO-based catalysts. Importantly, these results were achieved under mild conditions (120 ◦ C) using water as a solvent and without addition of external oxidant agents. Furthermore, the study observed a significant production of valuable (di) carboxylic acids, such as fumaric acid during the depolymerization process over optimized MgO catalyst. This research provides valuable insights into the potential of MgO as a sustainable catalyst for the selective conversion of lignin present in lignocellulosic biomass into valuable chemicals and biofuels.
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.