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Microstructure and activity of Pd catalysts prepared on commercial carbon support for the liquid phase decomposition of formic acid

Arzac, GM; Montes, O; Fernández, A
International Journal of Hydrogen Energy, 48 (2023) 2628-2639
Materiales Nanoestructurados y Microestructura


In this work, a series of Pd catalysts supported on commercially available activated carbon (Norit (R)) were prepared by employing different metal precursors (Pd(NO3)2 and Na2PdCl4) by the impregnation-reduction method at different pH. Catalysts were tested for the liquid phase decomposition of formic acid to generate hydrogen. The best results, in terms of small particle size and high catalytic activity were achieved for the Pd/C sample prepared by using Pd(NO3)2 salt impregnated at pH = 2.5, and reduced with sodium borohydride. The particle size of the best Pd/C catalyst is (4.1 +/- 1.4) nm with initial TOFs of 2929 and 683 h-1 at 60 and 30 degrees C respectively and an apparent activation energy of 40 kJ mol-1. Samples prepared by using Na2PdCl4 precursor, consisted of particles with higher size and thus lower activity than the ones prepared with Pd(NO3)2. Regardless the Pd precursor employed, the best results in terms of particle size and activity were achieved at the point of zero charge of the support when the Pd species and the carbon surface were both neutral. The impregnation pH not only determines the particle size, but also the nature of the reducing agent does. The catalytic activity was shown to be size-dependent and it was shown that a mixture of surface Pd0 and PdII oxidation states is beneficial for the activity. When comparing with literature catalysts with similar composition, we found that our best catalyst is competitive enough and that Norit (R) support could be promising for future studies on this reaction.

Enero, 2023 | DOI: 10.1016/j.ijhydene.2022.10.149

Selective hydrodeoxygenation of levulinic acid to gamma-valerolactone over Ru supported on functionalized carbon nanofibers

Bounoukta, CE; Megias-Sayago, C; Rendon, N; Ammari, F; Penkova, A; Ivanova, S; Centeno, MA; Odriozola, JA
Sustainable Energy & Fuels, 7 (2023) 857-867
Química de Superficies y Catálisis


In this work, carbon nanofibers (CNFs) have been successfully functionalized by using different approaches and finally used for the preparation of Ru based catalysts. The organometallic approach has been demonstrated to be suitable for CNF functionalization, leading to well-defined Ru NPs (by adding organosilane, amino or mercapto functionalities, among others) in comparison with mineral acid treatments conventionally used to activate and/or functionalize carbonaceous solids. All catalysts have been tested in levulinic acid hydrodeoxygenation to γ-valerolactone under mild conditions, with the impact of CNF functionalization on the catalysts' performance fully discussed in comparison with unmodified commercial CNFs.

Enero, 2023 | DOI: 10.1039/d2se01503j

Collective plasmonic resonances enhance the photoluminescence of rare-earth nanocrystal films processed by ultrafast annealing

Cabello-Olmo, E; Higashino, M; Murai, S; Tanaka, K; Lozano, G; Miguez, H
Chemical Communications, 59 (2023) 1289-1292
Materiales Ópticos Multifuncionales


Herein, we demonstrate that rapid thermal annealing allows achieving close-to-one photoluminescence quantum yield while preserving the transparency of rare-earth nanocrystal films, which further enables their integration with nanophotonics. The combination with periodic arrays of aluminum nanodisks that support collective plasmonic resonances leads to enhanced directional emission.

Enero, 2023 | DOI: 10.1039/d2cc04779a

Highly Nonstoichiometric YAG Ceramics with Modified Luminescence Properties

Cao, WW; Becerro, AI; Castaing, V; Fang, X; Florian, P; Fayon, F; Zanghi, D; Veron, E; Zandona, A; Genevois, C; Pitcher, MJ; Allix, M
Advanced Functional Materials
Materiales Ópticos Multifuncionales - Materiales Coloidales


Y3Al5O12 (YAG) is a widely used phosphor host. Its optical properties are controlled by chemical substitution at its YO8 or AlO6/AlO4 sublattices, with emission wavelengths defined by rare-earth and transition-metal dopants that have been explored extensively. Nonstoichiometric compositions Y3+xAl5-xO12 (x not equal 0) may offer a route to new emission wavelengths by distributing dopants over two or more sublattices simultaneously, producing new local coordination environments for the activator ions. However, YAG typically behaves as a line phase, and such compositions are therefore challenging to synthesize. Here, a series of highly nonstoichiometric Y3+xAl5-xO12 with 0 <= x <= 0.40 is reported, corresponding to <= 20% of the AlO6 sublattice substituted by Y3+, synthesized by advanced melt-quenching techniques. This impacts the up-conversion luminescence of Yb3+/Er3+-doped systems, whose yellow-green emission differs from the red-orange emission of their stoichiometric counterparts. In contrast, the YAG:Ce3+ system has a different structural response to nonstoichiometry and its down-conversion emission is only weakly affected. Analogous highly nonstoichiometric systems should be obtainable for a range of garnet materials, demonstrated here by the synthesis of Gd3.2Al4.8O12 and Gd3.2Ga4.8O12. This opens pathways to property tuning by control of host stoichiometry, and the prospect of improved performance or new applications for garnet-type materials.

Enero, 2023 | DOI: 10.1002/adfm.202213418

Responsive Optical Materials Based on Ligand-Free Perovskite Quantum Dots Embedded in Mesoporous Scaffolds

Romero-Perez, C; Zanetta, A; Fernandez-Delgado, N; Herrera-Collado, M; Hernandez-Saz, J; Molina, SI; Calio, L; Calvo, ME; Miguez, H
ACS Applied Materials & Interfaces 15 (2023) 1808-1816
Materiales Ópticos Multifuncionales


Herein we show that dispersing inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) in optical quality films, possessing an accessible and controlled pore size distribution, gives rise to fluorescent materials with a controlled and highly sensi t i v e response to ambient changes. A scaffold-based synthesis approach is employed to obtain ligand-free QDs, whose pristine surface endows them with high sensit i v i t y to the presence of different vapors in their vici n i t y . At the same time, the void network of the host offers a means to gradually expose the embedded QDs to such vapors. Under these conditions, the luminescent response of the QDs is mediated by the mesostructure of the matri x , which determines the rate at which vapor molecules will adsorb onto the pore walls and, eventually, condensate, filling the void space. With luminescence quantum yields as high as 60%, scaffold-supported ligand-free perovskite nanocrystals display intense photoemission signals over the whole process, as well as high photo-and chemical stabi l i t y , which allows illuminating them for long periods of time and recovering the original response upon desorption of the condensed phase. The results herein presented open a new route to explore the application of perovskite QD-based materials in sensing.

Enero, 2023 | DOI: 10.1021/acsami.2c16867

New Types and Dosages for the Manufacture of Low-Energy Cements from Raw Materials and Industrial Waste under the Principles of the Circular Economy and Low-Carbon Economy

Martinez-Martinez, S; Perez-Villarejo, L; Eliche-Quesada, D; Sanchez-Soto, PJ
Materials, 16 (2023) 802
Materiales Avanzados


The cement manufacturing industry is one of the main greenhouse gas emission producers and also consumes a large quantity of raw materials. It is essential to reduce these emissions in order to comply with the Paris Agreement and the principles of the circular economy. The objective of this research was to develop different types of cement clinker blends using industrial waste and innovative design to produce low-energy cement. Several types of waste have been studied as alternative raw materials. Their main characteristics have been analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD), Attenuated total reflectance Fourier trans-form infrared spectroscopy (ATR-FTIR), thermal analysis (TG-DTG-DSC) and scanning electron microscopy and energy dispersive X-ray spectroscopy analysis (SEM-EDS). The results obtained from the experimental work carried out in this research focused on the study of crude blends for low-energy cement created from industrial waste. The effect of the addition of different industrial waste types, as a substitution for raw materials, in the production of low-energy cement with high dicalcium silicate content has been investigated. Thus, the dosage design has been performed using modified Bogue equations and quality indexes (LSF, AM, and SM). The calculations of both the modified Bogue equations and quality indexes necessitate knowledge of the weight percentages of CaO, SiO2, Al2O3, and Fe2O3, determined via XRF. In this theoretical design of the different blends, it has been established that a dicalcium silicate ratio of 60-65 wt % and an LSF of 78-83% as the limit are values common to all of them. The calculation basis for the crude blends has been based on calcined materials. Therefore, the chemical composition was established, following this premise. Thus, it was possible to develop cement clinker blends with compositions of 50 wt % and 100 wt % using industrial wastes. This research has shown that the clinkerization process is one of the main options for the valorization of waste and its consideration for inclusion as a raw material within the circularity of the cement industry's production process. Thus, waste is used as a raw material for the production of a more useful substance, taking into account the fundamental principles of the circular economy.

Enero, 2023 | DOI: 10.3390/ma16020802

Thermal arrest analysis of the reverse martensitic transformation in a Ni55Fe19Ga26 Heusler alloy obtained by melt-spinning

Vidal-Crespo, A; Manchon-Gordon, AF; Blazquez, JS; Ipus, JJ; Svec, P; Conde, CF
Journal of Thermal Analysis and Calorimetry, (2023)
Reactividad de Sólidos


Ni55Fe19Ga26 ribbons obtained by melt-spinning technique exhibit a martensitic transformation from L2(1) cubic austenite phase to 14 M martensite phase above room temperature. We have taken advantage of the existence of thermal hysteresis of the martensitic phase transition (similar to 11 K) to analyze the effect of isothermal treatments on the reverse martensitic transformation, which has been analyzed by means of interrupted heating using differential scanning calorimetry. The experimental findings clearly indicate a time-depending effect in the martensitic transformation at temperatures between the austenite start and finish temperatures. Moreover, it has been observed that two successive martensitic transformations take place after the isothermal arrest was performed.

Enero, 2023 | DOI: 10.1007/s10973-022-11889-1

A novel, green, cost-effective and fluidizable SiO2-decorated calcium-based adsorbent recovered from eggshell waste for the CO2 capture process

Imani, M; Tahmasebpoor, M; Sanchez-Jim, P; Valverde, J; Garcia, VM
Separation and Purification Technology, 305 (2023) 122523
Reactividad de Sólidos


The reduction, storage, and reuse of greenhouse gas carbon dioxide (CO2) is a crucial concern in modern society. Bio-waste adsorbents have recently aroused the investigator's attention as auspicious materials for CO2 capture. However, the adsorption capacity decaying and poor fluidizability during carbonation/calcination cycles of all natural adsorbents used in the calcium-looping process (CaL) are important challenges. The current study ex-plores the performance of a novel SiO2-decorated calcium-based adsorbent recovered from eggshell waste in terms of both CO2 capture capacity and fluidity. Two preparation methods of hydration and sol-gel were used to obtain Ca-based adsorbents with different pore configurations and volumes. Modification of the adsorbents was applied by dry physically mixing with different weight percentages of hydrophobic SiO2 nanoparticles (NPs), in order to maintain stability and fluidity. The adsorbent prepared by the sol-gel method exhibited a fluffier structure with smaller grain sizes and higher porosity than that of prepared by the hydration method, leading to a 6.9 % increase in conversion at the end of the 20th cycle. Also, with the optimal amount of SiO2 nanoparticles, i. e. 7.5 wt%, the amount of CaO conversion obtained by sol-gel derived adsorbent was 27.59 % higher than that by pristine eggshell at the end of the 20th carbonation/calcination cycles. The fluidizability tests showed that the highest bed expansion ratio (2.29) was achieved for sol-gel derived adsorbent in the presence of 7.5 wt% silica nanoparticles which was considerably higher than the amount of 1.8 and 1.6 belonged to sol-gel derived adsorbent and pristine eggshell without silica at the gas velocity of approximate to 6.5 cm/s, respectively. The high adsorption capacity and proper fluidity of this novel and green calcium-based adsorbent promise its wide application.

Enero, 2023 | DOI: 10.1016/j.seppur.2022.122523


Pd supported on defective TiO2 polymorphic mixtures: Effect of metal-support interactions upon glycerol selective oxidation

Rinaudo, MG; Beltran, AM; Fernandez, A; Cadus, LE; Morales, MR
Results in Engineering, 16 (2022) 100737
Materiales Nanoestructurados y Microestructura


Palladium catalysts supported on defective mixes of anatase, TiO2 (II) and rutile crystalline phases, previously obtained by high-energy ball milling, were synthesized and tested for glycerol selective oxidation. A deep characterization of these unusual materials was carried out to elucidate catalytic and physicochemical features. Electron density transfer from support to metal or vice versa, depending on the polymorphs present, could not only alter palladium particle sizes and its surface oxidation state but also reducibility and oxygen mobility of catalysts. Furthermore, acid-base properties achieved also influenced catalytic activity under mild conditions of liquid-phase glycerol oxidation. A conversion of 94% and a selectivity to glyceric and lactic acids of 48% and 22% respectively were obtained for the Pd catalyst supported on mechanochemically activated anatase. The presence of several polymorphs in a metal oxide support could therefore benefit or handicap catalytic cycle for a particular reaction. Metal-support interactions play a key role in heterogenous catalysts and thus the rational design of supports comes on the scene.

Diciembre, 2022 | DOI: 10.1016/j.rineng.2022.100737

Theoretical Analysis of Polynuclear Zinc Complexes Isolobally Related to Hydrocarbons

Ayala, R; Galindo, A
International Journal of Molecular Sciences, 23 (2022) 14858
Reactividad de Sólidos


Based on the isolobal analogy of ZnCp (Cp = eta(5)-C5H5) and ZnR (R = alkyl or aryl group) fragments with hydrogen atom and fragment [Zn(CO)(2)] with a CH2 carbene, the following complexes [(ZnCp)(2){mu-Zn(CO)(2)}], 1, [(ZnPh)(2){mu-Zn(CO)(2)}], 2, [(ZnPh){mu-Zn(CO)(2)}(ZnCp)], 3, [(ZnCp)(2){mu-Zn-2(CO)(4)}], 4, [(ZnPh)(2){mu-Zn-2(CO)(4)}], 5, [(ZnPh){mu-Zn(CO)(2)}(2)(ZnCp)], 6, [Zn-3(CO)(6)], 7 and [Zn-5(CO)(10)], 8, were built. These polynuclear zinc compounds are isolobally related to simple hydrocarbons (methane, ethane, cyclopropane and cyclopentane). They have been studied by density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) to compare the nature and topology of the Zn-Zn bond with previous studies. There are bond critical points (BCPs) between each pair of adjacent Zn centers in complexes 1-8 with Zn-Zn distances within the range 2.37-2.50 angstrom. The nature of the Zn-Zn bond in these complexes can be described as polar rather than pure covalent bonds. Although in a subtle way, the presence of different ligands and zinc oxidation states introduces asymmetry and polarity in the Zn-Zn bond. In addition, the Zn-Zn bond is delocalized in nature in complex 7 whereas it can be described as a localized bond for the remaining zinc complexes here studied.

Diciembre, 2022 | DOI: 10.3390/ijms232314858

Materials challenges and opportunities to address growing micro/ nanoplastics pollution: a review of thermochemical upcycling

Parrilla-Lahoz, S; Mahebadevan, S; Kauta, M; Zambrano, MC; Pawlak, JJ; Venditti, RA; Reina, TR; Duyar, MS
Materials Today Sustainability, 20 (2022) 100200
Química de Superficies y Catálisis


Micro/nanoplastics have sparked attention in recent years due to their widespread presence in the environment. Currently, several waste valorization approaches are under development in order to upcycle micro/nanoplastics. Thermal conversion technologies such as pyrolysis, gasification, liquefaction, or hydrothermal carbonization can yield high-value solid products, oil, and gases from plastics waste. The common thermal conversion technologies investigated focus on maximizing the production of oil and gases (such as H2 and CH4) for use as fuel. Except for hydrogen, when these products are used to generate energy, the carbon emissions generated are comparable to those produced by traditional fossil fuels. Herein, we present a review of the current efforts to capture and convert plastic waste into valuable products with an emphasis on identifying the need to develop processes specifically for micro/nano-plastics while also preventing the release of CO2 emissions. We identify the development of efficient catalytic materials as a critical research need for achieving economically viable thermochemical con-version of micro/nanoplastics.

Diciembre, 2022 | DOI: 10.1016/j.mtsust.2022.100200

Development of Power-to-X Catalytic Processes for CO2 Valorisation: From the Molecular Level to the Reactor Architecture

Bobadilla, LF; Azancot, L; Luque-Alvarez, LA; Torres-Sempere, G; Gonzalez-Castano, M; Pastor-Perez, L; Ramírez-Reina, T; Ivanova, S; Centeno, MA; Odriozola, JA
Chemistry-SWITZERLAND, 4 (2022) 1250-1280
Química de Superficies y Catálisis


Nowadays, global climate change is likely the most compelling problem mankind is facing. In this scenario, decarbonisation of the chemical industry is one of the global challenges that the scientific community needs to address in the immediate future. Catalysis and catalytic processes are called to play a decisive role in the transition to a more sustainable and low-carbon future. This critical review analyses the unique advantages of structured reactors (isothermicity, a wide range of residence times availability, complex geometries) with the multifunctional design of efficient catalysts to synthesise chemicals using CO2 and renewable H-2 in a Power-to-X (PTX) strategy. Fine-chemistry synthetic methods and advanced in situ/operando techniques are essential to elucidate the changes of the catalysts during the studied reaction, thus gathering fundamental information about the active species and reaction mechanisms. Such information becomes crucial to refine the catalyst's formulation and boost the reaction's performance. On the other hand, reactors architecture allows flow pattern and temperature control, the management of strong thermal effects and the incorporation of specifically designed materials as catalytically active phases are expected to significantly contribute to the advance in the valorisation of CO2 in the form of high added-value products. From a general perspective, this paper aims to update the state of the art in Carbon Capture and Utilisation (CCU) and PTX concepts with emphasis on processes involving the transformation of CO2 into targeted fuels and platform chemicals, combining innovation from the point of view of both structured reactor design and multifunctional catalysts development.

Diciembre, 2022 | DOI: 10.3390/chemistry4040083

CO2 methanation on Ni/YMn1-xAlxO3 perovskite catalysts

Safdar, M; Gonzalez-Castano, M; Penkova, A; Centeno, MA; Odriozola, JA; Arellano-Garcia, H
Applied Materials Today, 29 (2022) 101577
Química de Superficies y Catálisis


Seeking for advanced catalytic systems for the CO2 methanation reaction, the use of Ni supported catalysts over redox materials is often proposed. Profiting the superior redox properties described for layered perovskite systems, this work has investigated a series Ni supported YMn1-xAlxO3 (x = 0, 0.2, 0.5, 0.8, 1) perovskite catalysts. The obtained results evidenced the impact of the support nature on the systems redox properties and Ni-support interactions. Within the catalysts series, the greater methanation rates displayed by Ni/YMn0.5Al0.5O3 catalyst (0.748 mmol(CO2,conv.)s(-1) g(Ni)(-1) at 400 ? and 60 L/gh) were associated to the interplay between the support redox properties and superior Ni dispersion. The improved redox behavior attained through the Al-incorporation (up to x = 0.5) was associated to the layered perovskite structures which, being distorted and constituted by smaller crystal sizes, facilitated the behavior of Mn redox couples as surface species readily interconverted. Exhibiting catalytic performances comparable to precious metals based catalysts, this work proposes the Ni/YMn0.5Al0.5O3 catalyst as an effective system for the CO2 methanation reaction.

Diciembre, 2022 | DOI: 10.1016/j.apmt.2022.101577

Assessment of pilot-plant scale solar photocatalytic hydrogen generation with multiple approaches: Valorization, water decontamination and disinfection

Ruiz-Aguirre, A; Villachica-Llamosas, JG; Polo-Lopez, MI; Cabrera-Reina, A; Colon, G; Peral, J; Malato, S
Energy, 260 (2022) e10272
Materiales y Procesos Catalíticos de Interés Ambiental y Energético


The main goal of the present study was to explore pilot-scale combination of H-2 generation with simultaneous water disinfection or decontamination. Performance of a TiO2-CuO mixture for solar-to-hydrogen (STH) con-version was studied, focusing on treatment optimization (catalyst dose, proportion of semiconductors in the mixture and concentration of the sacrificial agent). Experiments were performed in a 25-L compound parabolic collector (2 m(2)) solar pilot plant specifically designed for photocatalytic hydrogen generation. The best operating conditions were 100 mg L-1 TiO2-CuO (10:1) with 0.075 M glycerol as the sacrificial agent. The best STH conversion attained was 0.9%. 25 mg L-1 imidacloprid was completely degraded (over 99%). The synergetic effect of anoxic conditions, TiO2:CuO and solar radiation caused a significant reduction (> 5 Log) in concen-tration of E. coli, used as a model waterborne pathogen, in less than 10 min.

Diciembre, 2022 | DOI: 10.1016/

High-Quality SiO2/O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry

Canas, J; Reyes, DF; Zakhtser, A; Dussarrat, C; Teramoto, T; Gutierrez, M; Gheeraert, E
Nanomaterials, 12 (2022) 4125
Tribología y Protección de Superficies


Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap. In this work, the heterojunction of atomic-layer-deposited silicon oxide and (100)-oriented p-type oxygen-terminated diamond is studied using scanning transmission electron microscopy in its energy loss spectroscopy mode and X-ray photoelectron spectroscopy. The amorphous phase of silicon oxide was successfully synthesized with a homogeneous band-gap of 9.4 eV. The interface between the oxide and diamond consisted mainly of single- and double-carbon-oxygen bonds with a low density of interface states and a straddling band setting with a 2.0 eV valence band-offset and 1.9 eV conduction band-offset.

Diciembre, 2022 | DOI: 10.3390/nano12234125

Nanoantennas Patterned by Colloidal Lithography for Enhanced Nanophosphor Light Emission

Viana, JM; Romero, M; Lozano, G; Míguez, H
ACS Applied Nano Materials, 5(11) (2022) 16242-16249
Materiales Ópticos Multifuncionales


Transparent coatings made of rare-earth doped nanocrystals, also known as nanophosphors, feature efficient photoluminescence and excellent thermal and optical stabi l i t y . Herein, we demonstrate that the optical antennas prepared by colloidal lithography render thin nanophosphor films with a brighter emission. In particular, we fabricate gold nanostructures in the proximity of GdVO4:Eu3+ nanophosphors by metal evaporation using a mask made of a monolayer of polymer beads arranged in a triangular lattice. Optical modes supported by the antennas can be controlled by tuning the diameter of the polymer spheres in the colloidal mask, which determines the shape of the gold nanostructure, as confirmed by numerical simulations. Confocal microscopy reveals that metallic antennas induce brighter photoluminescence at specific spatial regions of the nanophosphor film at targeted frequencies as a result of the coupling between gold nanostructures and nanophosphors. Patterning of nanophosphor thin layers with arrays of metallic antennas offers an inexpensive nanophotonic solution to develop bright emitting coatings of interest for color conversion, labeling , or anti-counterfeiting.

Noviembre, 2022 | DOI: 10.1021/acsanm.2c03258

Reactive flash sintering of SrFe12O19 ceramic permanent magnets

Manchon-Gordon, AF; Sanchez-Jimenez, PE; Blazquez, JS; Perejon, A; Perez-Maqueda, LA
Journal of Alloys and Compounds, 922 (2022) 166203
Reactividad de Sólidos


Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This technique allows preparing sintered SrFe12O19 at a furnace temperature of just 973 K during just 2 min by applying a modest field of 40 V cm(-1), instead of the conventional sintering process employed in ferrite magnet manufacturing that demands high temperature and long dwell times. Analysis of structural and magnetic properties were performed as a function of time in which the flash event was held. Mossbauer spectra show the existence of five different kinds of local environments, confirming the formation of strontium hexaferrite. The resulting samples exhibit comparable magnetic properties to the state-of-the-art ferrite magnets. In particular, produced samples reach a coercivity of 0.4 T and a specific saturation magnetization of 70 Am-2 kg(-1).

Noviembre, 2022 | DOI: 10.1016/j.jallcom.2022.166203

Exploring the local environment of the engineered nanoclay Mica-4 under hydrothermal conditions using Eu(3+)as a luminescent probe

Martin-Rodriguez, R; Aguado, F; Alba, MD; Valiente, R; Pavon, E; Perdigon, AC
Journal of Alloys and Compounds, 921 (2022) 166086
Materiales de Diseño para la Energía y Medioambiente


High charge mica Na4Al4Si4Mg6O20F4 , Mica-4, is a promising candidate as a filling material to immobilize high-level radioactive waste in deep geological repositories due to its extraordinary adsorption capacity. In contrast to traditional clay materials, the structural composition of this mica, with a high content of alu-minum in the tetrahedral sheet, enhances its chemical reactivity, favoring the formation of new crystalline phases under mild hydrothermal conditions, and thus providing a definitive isolation of the radionuclides in the engineered barrier. Moreover, this synthetic clay has some features that allow its use as an optical sensor by doping with luminescent rare earth cations such as Eu3+. In this paper we discuss the local structure of the nanoclay Mica-4 using Eu3+ as a local probe to track the physical and chemical modifica-tions under hydrothermal conditions. For that purpose, a set of hydrothermal experiments has been carried out heating Mica-4 and an aqueous Eu(NO3)(3) solution in a stainless steel reactor at different temperatures and times. Optical properties of the as-treated samples were characterized by spectroscopic measurements. The fine peak structure of emission and the relative intensity of different Eu3+ transitions as well as the luminescence lifetime have been correlated with the structure and composition of this nanoclay, and the interaction mechanisms between the lanthanide ions and the clay mineral at different temperatures and times. Special attention has been paid to understanding the role of the aluminum content, which may act as either an aggregating or dispersing agent, in the optical features and reactivity of the system.

Noviembre, 2022 | DOI: 10.1016/j.jallcom.2022.166086

Improvement in cyclic CO2 capture performance and fluidization behavior of eggshell-derived CaCO3 particles modified with acetic acid used in calcium looping process

Imani, M; Tahmasebpoor, M; Sanchez-Jimenez, PE; Valverde, JM; Moreno, V
Journal of CO2 Utilization, 65 (2022) 102207
Reactividad de Sólidos


Although calcium-based materials are the most promising adsorbents used in calcium looping process for carbon dioxide removing, their CO2 capture capacity decaying besides poor fluidization, still are the important challenges. In the present investigation, eggshell as a cheap, easily available and unpolluted source of calcium carbonate was used for CO2 capturing in calcium looping process. Eggshell particles were treated with various volume concentrations of acetic acid to improve its sorption capacity. According to the TGA results after 20 carbonation/calcination cycles, the effective carbonation conversion of modified eggshell with 5%, 20%, 30% and 40%. v/v acetic acid was 21.33%, 24.26%, 25.97% and 28.97%, respectively, which is considerable compared to 20.54% for untreated eggshell. The effect of initial eggshell particle size on the adsorption behavior of final adsorbent was also investigated by using two different sizes including dp < 45 mu m and dp > 320 mu m. The results showed that the effective conversion of the adsorbent containing 40%. v/v acetic acid derived from small particle size eggshells was 9.32% higher than that from larger particle size eggshells. In terms of fluidization behavior, surprisingly the addition of acetic acid to the eggshell particles also increased the bed expansion ratio as 8% and 36.2% at gas velocities of 0.27 and 6.67 cm/s, respectively. Further improvement in the fluidity of eggshell modified with 40% acid was performed by manually mixing of SiO2 nanoparticles at different weight percentages. According to the results, adding 7.5 wt% SiO2 leaded to the homogeneous and agglomerate particulate fluidization.

Noviembre, 2022 | DOI: 10.1016/j.jcou.2022.102207

Biopolymer-Based Films Reinforced with FexOy-Nanoparticles

Abdullah, JAA; Jimenez-Rosado, M; Benitez, JJ; Guerrero, A; Romero, A
Polymers, 14 (2022) 4487
Materiales de Diseño para la Energía y Medioambiente


Nowadays, natural polymer-based films are considered potentially environmentally friendly alternatives to conventional plastic films, due to many advantageous properties, including their easy processability, high flexibility, non-toxicity, low cost, high availability, and environmental safety. However, they are limited in their application by a number of shortcomings, including their high water solubility and vapor permeability as well as their poor opacity and low mechanical resistance. Thus, nanoparticles, such as green FexOy-NPs, can be used to overcome the drawbacks associated with these materials. Therefore, the aim of this study was to develop three different polymer-based films (gelatin-based, cellulose acetate-based and chitosan-based films) containing green synthesized FexOy-NPs (1.0% w/w of the initial polymer weight) as an additive to improve film properties. This was accomplished by preparing the different films using the casting method and examining their physicochemical, mechanical, microstructural, and functional characteristics. The results show that the incorporation of FexOy-NPs into the different films significantly enhanced their physicochemical, mechanical, and morphological properties as well as their antioxidant characteristics. Consequently, it was possible to produce suitable natural polymer-based films with potential applications across a wide range of industries, including functional packaging for food, antioxidants, and antimicrobial additives for pharmaceutical and biomedical materials as well as pesticides for agriculture.

Noviembre, 2022 | DOI: 10.3390/polym14214487