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A direct in situ observation of water-enhanced proton conductivity of Eu-doped ZrO2: Effect on WGS reaction

Garcia-Moncada, N; Bobadilla, LF; Poyato, R; Lopez-Cartes, C; Romero-Sarria, F; Centeno, MA; Odriozola, JA
Applied Catalysis B-Environmental, 231 (2018) 343-356


Eu-doped ZrO2 solid solutions have been synthesized in order to prepare proton conductors as water-enhancer additives for the WGS reaction. Elemental characterization has been carried out revealing homogeneous dopant distribution resulting in fluorite-type solid solutions for Eu2O3 contents up to similar to 9 mol.%. Representative samples of the Eu-doped ZrO2 series have been analysed by Impedance Spectroscopy (IS) in inert, oxygen and wet conditions. The solid solution with 5 mol.% of Eu2O3 has presented the highest conductivity values for all tested conditions indicating an optimal amount of dopant. Moreover, the presence of vapour pressure results in an increment of the conductivity at temperatures lower than 300 degrees C, meanwhile at higher temperatures the conductivity is the same than that in inert conditions. To elucidate these results, in situ DRIFTS studies were carried out. These experiments evidenced the existence of water dissociation at oxygen vacancies (band at 3724 cm(-1)) as well as the presence of physisorbed water at temperatures up to similar to 300 degrees C where the band at 5248 cm(-1) characteristic of these species disappeared. These results points to a layer model where the physisorbed water interacts with surface hydroxyls generated by dissociated water that improves the proton conductivity through Grotthuss' mechanism in the RT-300 degrees C temperature range. These samples were successfully tested in WGS reaction as additive to a typical Pt-based catalyst. The presence of the mixed oxide reveals an increase of the catalyst' activity assisted by the proton conductor, since improves the water activation step.

Septiembre, 2018 | DOI: 10.1016/j.apcatb.2018.03.001

ZnO and Pt-ZnO photocatalysts: Characterization and photocatalytic activity assessing by means of three substrates

Jaramillo, N; Navio, J.A.; Hidalgo, M.C.; Macías, M.
Catalysis Today, 313 (2018) 12-19


ZnO nanoparticles have been previously synthesized by a facile precipitation procedure by mixing aqueous solutions of Zn(II) acetate and dissolved Na2CO3 at pH ca. 7.0 without the addition of a template. The as-prepared ZnO material was anealed at 400 °C in air for 2 h. The Pt-ZnO catalysts (0.5 or 1.0 Pt wt.%) were obtained by photochemical deposition method on the surface of the prepared ZnO sample, using hexachloroplatinic acid (H2PtCl6). It has been shown that Zn2+ is lost from the photocatalyst to the medium and a replacement of the cationic vacancies of Zn2+ by Pt4+ cations occurs during the platinization process of the ZnO samples, regardless of whether the platinum metal photodeposition process. The as-prepared catalysts were characterized by XRD, BET, FE-SEM, TEM, XPS and diffuse reflectance spectroscopy (DRS). Three different probe molecules were used to evaluate the photocatalytic properties under UV-illumination: Methyl Orange and Rhodamine B were chosen as dye substrates and Phenol as a transparent substrate. High conversion values (ca. 100%) and a total organic carbon (TOC) removal of 90–96%, were obtained over these photocatalysts after 160 min of UV illumination. In general, it was observed that the presence of Pt on ZnO affects the lattice parameters and the crystallite size. Although ZnO can completely degrade RhB, MO and Phenol totally in ca. 60 min, the process is more efficient for Pt–ZnO photocatalysts.

Septiembre, 2018 | DOI: 10.1016/j.cattod.2017.12.009

Graphene or carbon nanofiber-reinforced zirconia composites: Are they really worthwhile for structural applications?

Cano-Crespo, R; Moshtaghioun, BM; Gomez-Garcia, D; Moreno, R; Dominguez-Rodriguez, A
Journal of the European Ceramic Society, 38 (2018) 3994-4002


The use of allotropic phases of carbon (i.e. nanotubes, graphene or carbon nanofibers) as second phases to design ceramic composites is a hot topic at present. Researchers try to provide a remarkable improvement of the parent ceramic assuming that some of the outstanding mechanical properties of these phases migrate to the resultant composite. This reasonable idea has been questioned severely in the case of nanotubes addition but there is not any analysis for the other two phases cited previously. To elucidate this question, zirconia was selected as a model ceramic. This paper reports the mechanical properties of zirconia composites reinforced either with graphene or carbon nanofibers, with special emphasis on the high-temperature plasticity.

Septiembre, 2018 | DOI: 10.1016/j.jeurceramsoc.2018.04.045

Vitrification and derived glass-ceramics from mining wastes containing vermiculite and lithium aluminium phosphate

Rincon, JM; Callejas, P; Sanchez-Soto, PJ; Jordan, MM
Materials Letters, 227 (2018) 86-89


The waste vitrification of abandoned open sky vermiculite deposits has been considered by combining with a natural phosphate mineral residue. Several batches haven been designed from the composition system: Li2O-MgO-Al2O3-P2O5-SiO2 including some Fe2O3 and Fluoride. The resulting glasses are transparent and smooth green coloured, giving rise after TTT treatments to several opal, opaque glass-ceramics with iridescent surface. Full characterization has been carried out by XRD and electron microscopy with EDS, as well as by XPS spectroscopies, concluding that the main crystalline phases formed were alpha-cordierite and beta-spodumene. The surface of these glass-ceramics from vermiculiteamblygonite is enriched in Fe2O3. Compared to the parent glasses, the final glass-ceramics exhibited and improvement in fracture toughness.

Septiembre, 2018 | DOI: 10.1016/j.matlet.2018.05.001

Solar pilot plant scale hydrogen generation by irradiation of Cu/TiO2 composites in presence of sacrificial electron donors

Maldonado, MI; Lopez-Martin, A; Colon, G; Peral, J; Martinez-Costa, JI; Malato, S
Applied Catalysis B-Environmental, 229 (2018) 15-23


A Cu/TiO2 photocatalyst has been synthesised by reducing a Cu precursor with NaBH4 onto the surface of a sulphate pretreated TiO2 obtained by a sol-gel procedure. The catalyst, that shows a clearly defined anatase phase with high crystallinity and relatively high surface area, and contains Cu2O and CuO deposits on its surface, has been used to produce hydrogen in a solar driven pilot plant scale photocatalytic reactor. Different electron donor aqueous solutions (methanol, glycerol, and a real municipal wastewater treatment plant influent) have been tested showing similar or even higher energy efficiency than those obtained using more expensive noble metal based photocatalytic systems. The glycerol solutions have provided the best reactive environments for hydrogen generation.

Agosto, 2018 | DOI: 10.1016/j.apcatb.2018.02.005

Effect of milling mechanism on the CO2 capture performance of limestone in the Calcium Looping process

Benitez-Guerrero, M; Valverde, JM; Perejon, A; Sanchez-Jimenez, PE; Perez-Maqueda, LA
Chemical Engineering Journal, 346 (2018) 549-556


This work analyzes the relevant influence of milling on the CO2 capture performance of CaO derived from natural limestone. Diverse types of milling mechanisms produce contrasting effects on the microstructure of the CaO formed after calcination of the milled limestone samples, which affects crucially the kinetics of carbonation at conditions for CO2 capture. The capture capacity of CaO derived from limestone samples milled using either shear or impact based mills is impaired compared to as-received limestone. After calcination of the milled samples, the resulting CaO porosity is increased while crystallinity is enhanced, which hinders carbonation. Conversely, if the material is simultaneously subjected to intense impact and shear stresses, CaO porosity is promoted whereas CaO cristanillity is reduced, which enhances carbonation in both the reaction and solid-state diffusion controlled regimes.

Agosto, 2018 | DOI: 10.1016/j.cej.2018.03.146

On the determination of thermal degradation effects and detection techniques for thermoplastic composites obtained by automatic lamination

Martin, MI; Rodriguez-Lence, F; Guemes, A; Fernandez-Lopez, A; Perez-Maqueda, LA; Perejon, A
Composites part A-Applied science and manufacturing, 111 (2018) 23-32


Automatic lay-up and in-situ consolidation with thermoplastic composite materials is a technology under research for its expected use in the profitable manufacturing of structural aeronautical parts. This study is devoted to analysing the possible effects of thermal degradation produced by this manufacturing technique. 
Rheological measurements showed that there is negligible degradation in PEEK for the temperatures reached during the process. Thermogravimetric analysis under linear heating and constant rate conditions show that thermal degradation is a complex process with a number of overlapping steps. A general kinetic equation that describes the degradation of the material with temperature has been proposed and validated. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that there is no remarkable degradation. The use of a combination of in-situ and ex-situ experimental techniques, including kinetic modelling, not only provides reliable information about degradation but also allows setting optimal processing conditions.

Agosto, 2018 | DOI: 10.1016/j.compositesa.2018.05.006

Photonic structuring improves the colour purity of rare-earth nanophosphors

Geng, DL; Cabello-Olmo, E; Lozano, G; Miguez, H
Materials Horizons, 5 (2018) 661-667


Nanophosphor integration in an optical cavity allows unprecedented control over both the chromaticity and the directionality of the emitted light, without modifying the chemical composition of the emitters or compromising their efficiency. Our approach opens a route towards the development of nanoscale photonics based solid state lighting.

Julio, 2018 | DOI: 10.1039/c8mh00123e

Plant cuticle under global change: Biophysical implications

Heredia-Guerrero, JA; Guzman-Puyol, S; Benitez, JJ; Athanassiou, A; Heredia, A; Dominguez, E
Global Change Biology, 24 (2018) 2749-2751


Climatic stressors due to global change induce important modifications to the chemical composition of plant cuticles and their biophysical properties. In particular, plant cuticles can become heavier, stiffer and more inert, improving plant protection.

Julio, 2018 | DOI: 10.1111/gcb.14276

Structural, optical and X-ray attenuation properties of Tb3+: BaxCe1-xF3-x (x=0.18-0.48) nanospheres synthesized in polyol medium

Gonzalez-Mancebo, D; Becerro, AI; Genevois, C; Allix, M; Corral, A; Parrado-Gallego, A; Ocana, M
Dalton Transactions, 47 (2018) 8382-8391


Uniform Ba0.18Ce0.82F2.82 nanospheres have been obtained after aging a solution of barium and cerium nitrates and sodium tetrafluoroborate in a mixture of ethylene glycol and water at 120 degrees C for 20 hours. The diameter of the spheres could be tailored from 65 nm to 80 nm by varying the NaBF4 concentration while maintaining their colloidal stability in aqueous suspension. Increasing the aging temperature led to a phase transformation from hexagonal to cubic symmetry and to a concomitant increase of the Ba/Ce ratio, which reached a value close to the nominal one (50/50) at 240 degrees C. The same method was successful in obtaining Tb3+-doped nanospheres with homogeneous cation distribution and the same morphological features as the undoped material. An intense green emission was observed after the excitation of the Tb3+-doped samples through the Ce3+-Tb3+ energy transfer (ET) band. The ET efficiency increased with increasing Tb content, the maximum emission being observed for the 10% Tb-doped nanospheres. Aqueous suspensions of the latter sample showed excellent X-ray attenuation values that were superior to those of an iodine-based clinically approved contrast agent. Their fluorescence and X-ray attenuation properties make this material a potential dual bioprobe for luminescence bioimaging and X-ray computed tomography.

Julio, 2018 | DOI: 10.1039/c8dt01202d

Design of Ag/ and Pt/TiO2-SiO2 nanomaterials for the photocatalyti degradation of phenol under solar irradiation

Matos, J; Llano, B; Montana, R; Poon, PS; Hidalgo, MC
Environmental Science and Pollution Research, 25 (2018) 18894-18913


The design of hybrid mesoporous TiO2-SiO2(TS1) materials decorated with Ag and Pt nanoparticles was performed. The photocatalytic degradation of phenol under artificial solar irradiation was studied and the activity and selectivity of the intermediate products were verified. TiO2-SiO(2)was prepared by sol-gel method while Ag- and Pt-based photocatalysts (TS1-Ag and TS1-Pt) were prepared by photodeposition of the noble metals on TS1. Two series of photocatalysts were prepared varying Ag and Pt contents (0.5 and 1.0 wt%). An increase in the photocatalytic activity up to two and five times higher than TS1 was found on TS1-Ag-1.0 and TS1-Pt-1.0, respectively. Changes in the intermediate products were detected on Ag- and Pt-based photocatalysts with an increase in the catechol formation up to 3.3 and 6.6 times higher than that observed on TS1, respectively. A two-parallel reaction mechanism for the hydroquinone and catechol formation is proposed. A linear correlation between the photocatalytic activity and the surface concentration of noble metals was found indicating that the electron affinity of noble metals is the driven force for both the increase in the photoactivity and for the remarkable changes in the selectivity of products.

Julio, 2018 | DOI: 10.1007/s11356-018-2102-3

The effect of vitreous phase on mullite and mullite-based ceramic composites from kaolin wastes as by-products of mining, sericite clays and kaolinite

Sanchez-Soto, PJ; Eliche-Quesada, D; Martinez-Martinez, S; Garzon-Garzon, E; Perez-Villarejo, L; Rincon, JM
Materials Letters, 223 (2018) 154-158


Mullite precursors were prepared using kaolin waste, sericite clay containing kaolinite and industrial kaolin with addition of alumina in a wet medium to synthesize mullite (72 wt% Al2O3 and 28 wt% SiO2). Uniaxial pressed bars of the powdered mullite precursors were fired in the range 1400-1600 degrees C with soaking times 30-120 min. The resultant materials were studied by XRD and SEM-EDX. Bulk densities, apparent porosities and flexural strengths in four points were determined in the fired bars at 1500, 1550 and 1600 degrees C. It was concluded that the thermal behaviour of these mullite precursors was influenced by the presence of impurities in the raw materials. These impurities originate a liquid phase forming a glassy phase which produces a progressive and enhanced densification of the mullite materials by reaction sintering at 1500-1600 degrees C. The technical properties were also influenced by the relative proportion of vitreous phase. The microstructure of characteristic mullite crystals was revealed by SEM. It was emphasized the use of kaolin waste by-products of mining and sericite clays as valuable raw materials for mullite preparation.

Julio, 2018 | DOI: 10.1016/j.matlet.2018.04.037

Photo/Electrocatalytic Properties of Nanocrystalline ZnO and La–Doped ZnO: Combined DFT Fundamental Semiconducting Properties and Experimental Study

Ahsaine, A.H.; Slassi, A.; Naciri, Y.; Chennah, A.; Jaramillo‐Páez, C.; Anfar, Z.; Zbair, M.; Benlhachemi, A.; Navío, J.A.
Chemistry Select, 3 (2018) 77778-7791


This work reports the synthesis of nanocrystalline ZnO and 5% La‐doped ZnO (La/ZnO) materials for photo/electrocatalytic degradation of Rhodamine B. The samples were characterized by X‐Ray diffraction, scanning and transmission electron microscopy, X‐Ray photoelectron spectroscopy and diffuse reflectance spectra. The effect of La doping on electronic structure was investigated using density functional theory calculations (DFT), La‐doped ZnO showed an n‐type metallic nature compared to pristine ZnO and La doping creates occupied states within the band gap edge. Under UV light, La/ZnO showed higher kinetic constant and efficiency than ZnO. A possible mechanism was elaborated on the basis of DFT and active trapping measurements. Different initial Rhodamine B concentration were studied to assess the electro‐oxidation of RhB. The electrochemical degradation of RhB over La/ZnO spindles electrode was pronounced with three time's high kinetic constant. The superior electro/photoactivity of La/ZnO was due to its unique morphology, high charge separation of the charge carriers and higher conductivity induced by La‐doping (intermediary levels). Superoxide ions and holes were the main active species for the photodegradation. Whereas, synergetic effect of hydroxyl radicals and hypochlorite ions were responsible of the high RhB electrocatalytic degradation.

Julio, 2018 | DOI: 10.1002/slct.201801729

Comparison of solvent extraction and extraction chromatography resin techniques for uranium isotopic characterization in high-level radioactive waste and barrier materials

Hurtado-Bermudez, S; Villa-Alfageme, M; Mas, JL; Alba, MD
Applied Radiation and Isotopes, 137 (2018) 177-183


The development of Deep Geological Repositories (DGP) to the storage of high-level radioactive waste (HLRW) is mainly focused in systems of multiple barriers based on the use of clays, and particularly bentonites, as natural and engineered barriers in nuclear waste isolation due to their remarkable properties. 
Due to the fact that uranium is the major component of HLRW, it is required to go in depth in the analysis of the chemistry of the reaction of this element within bentonites. The determination of uranium under the conditions of HLRW, including the analysis of silicate matrices before and after the uranium-bentonite reaction, was investigated. The performances of a state-of-the-art and widespread radiochemical method based on chromatographic UTEVA resins, and a well-known and traditional method based on solvent extraction with tri-n-butyl phosphate (TBP), for the analysis of uranium and thorium isotopes in solid matrices with high concentrations of uranium were analysed in detail. 
In the development of this comparison, both radiochemical approaches have an overall excellent performance in order to analyse uranium concentration in HLRW samples. However, due to the high uranium concentration in the samples, the chromatographic resin is not able to avoid completely the uranium contamination in the thorium fraction.

Julio, 2018 | DOI: 10.1016/j.apradiso.2018.04.008

Unexpected Optical Blue Shift in Large Colloidal Quantum Dots by Anionic Migration and Exchange

Acebron, M; Galisteo-Lopez, JF; Lopez, C; Herrera, FC; Mizrahi, M; Requejo, FG; Palomares, FJ; Juarez, BH
Journal of Physical Chemistry Letters, 9 (2018) 3124-3130


Compositional changes taking place during the synthesis of alloyed CdSeZnS nanocrystals (NCs) allow shifting of the optical features to higher energy as the NCs grow. Under certain synthetic conditions, the effect of those changes on the surface/interface chemistry competes with and dominates over the conventional quantum confinement effect in growing NCs. These changes, identified by means of complementary advanced spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy), are understood in the frame of an ion migration and exchange mechanism taking place during the synthesis. Control over the synthetic routes during NC growth represents an alternative tool to tune the optical properties of colloidal quantum dots, broadening the versatility of the wet chemical methods.

Junio, 2018 | DOI: 10.1021/acs.jpclett.8b00741

Pressure Effect on the Multicycle Activity of Natural Carbonates and a Ca/Zr Composite for Energy Storage of Concentrated Solar Power

Sarrion, B; Sanchez-Jimenez, PE; Perejon, A; Perez-Maqueda, LA; Valverde, JM
ACS Sustainable Chemistry & Engineering, 6 (2018) 7849-7858


This work is focused on the use of the Calcium-Looping process (CaL) in Concentrated Solar Power (CSP) plants for Thermochemical Energy Storage (TCES). Cheap, abundant and nontoxic natural carbonate minerals, such as limestone and dolomite, can be employed in this application to store energy through the cyclic calcination/carbonation of CaCO3. In a recent work, a closed CO2 cycle has been proposed for an efficient CaL-CSP integration in which the CO2 in excess effluent from the carbonator is used to generate electricity by means of a gas turbine. Process simulations show that the thermoelectric efficiency is enhanced as the carbonator pressure and temperature are increased provided that the multicycle CaO conversion is not affected. On the other hand, the use of just one reactor for both calcination and carbonation has been suggested to reduce capital cost. However, the experimental results shown in the present work indicate that sintering is notably enhanced as the pressure in the reactor is increased. Such an adverse effect is mitigated for a ZrO2/CaCO3 composite with a low Zr content as compared to natural carbonates. These results are relevant to process simulations for better assessing the global efficiency of the CaL-CSP integration.

Junio, 2018 | DOI: 10.1021/acssuschemeng.8b00981

Room temperature synthesis of water-dispersible Ln(3+):CeF3 (Ln = Nd, Tb) nanoparticles with different morphology as bimodal probes for fluorescence and CT imaging

Gonzalez-Mancebo, D; Becerro, AI; Rojas, TC; Olivencia, A; Corral, A; Balcerzyk, M; Cantelar, E; Cusso, F; Ocana, M
Journal of Colloid and Interface Science, 520 (2018) 134-144


The singular properties of lanthanide-based inorganic nanoparticles (NPs) has raised the attention of the scientific community in biotechnological applications. In particular, those systems with two or more functionalities are especially interesting. In this work, an effective and commercially attractive procedure has been developed that renders uniform, water-dispersible Ln(3+):CeF3 (Ln = Tb, Nd) NPs with different shapes and size. The method consists of the homogeneous precipitation, in a mixture of polyol and water, of cations and anions using precursors that allow the controlled release of the latter. The advantages of the reported method are related to the absence of surfactants, dispersing agents or corrosive precursors as well as to the room temperature of the process. The obtained Tb:CeF3 NPs produce an intense emission after excitation through the Ce-Tb energy transfer band located in the UV spectral region, thus being potentially useful as phosphors for in-vitro imaging purposes. On the other hand, the synthesized Nd:CeF3 NPs are good candidates for in-vivo imaging because their excitation and emission wavelengths lie in the biological windows. Finally, the excellent X-ray attenuation efficacy of the Nd:CeF(3)NPs is shown, which confers double functionality to this material as both luminescence bioprobe and contrast agent for X-ray computed-tomography. 

Junio, 2018 | DOI: 10.1016/j.jcis.2018.03.007

Strong activation effect on a ru-co-c thin film catalyst for the hydrolysis of sodium borohydride

Arzac, GM; Paladini, M; Godinho, V; Beltran, AM; de Haro, MCJ; Fernandez, A
Scientific Reports, 8 (2018) art. 9755


In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported. This catalyst reached in the second cycle an activity 5 times higher than the initial (maximum activity 9310 ml.min(-1).g(CoRu)(-1) at 25 degrees C). Catalytic studies and characterization of the fresh and used samples permitted to attribute the strong activation effect to the following factors: (i) small column width and amorphous character (ii) the presence of Ru and (iii) dry state before each cycle. The presence of boron in the initial composition is detrimental to the durability. Our studies point out to the idea that after the first cycle the activity is controlled by surface Ru, which is the most active of the two metals. Apart from the activation effect, we found that catalysts deactivated in further cycles. We ascribed this effect to the loss of cobalt in the form of hydroxides, showing that deactivation was controlled by the chemistry of Co, the major surface metal component of the alloy. Alloying with Ru is beneficial for the activity but not for the durability, and this should be improved.

Junio, 2018 | DOI: 10.1038/s41598-018-28032-6

Effects of milling time, sintering temperature, Al content on the chemical nature, microhardness and microstructure of mechanochemically synthesized FeCoNiCrMn high entropy alloy

Alcala, MD; Real, C; Fombella, I; Trigo, I; Cordoba, JM
Journal of Alloys and Compounds, 749 (2018) 834-843


FeCoNiCrMn(Al)-based powdered high entropy alloys were synthesized by a short time mechanical alloying process in a high energy planetary ball milling from mixtures of elemental powders, and subsequently sintered by a pressureless procedure. The composition and microstructure of the HEA phases before and after the sintering process were studied by X-ray diffraction, energy dispersive X-ray analysis (EDX) and scanning electron microscopy. The microhardness and tensile strength values for Fe1,8Co1,8Ni1,8Cr1,8Mn1,8Al1,0 HEA sintered at 1400 degrees C sample were 3,7 GPa and 1011 MPa, respectively. Statistical Fisher-Pearson coefficient of skewness and kurtosis were played to determine the optimum synthesis milling time. The use of NaCl as additive led on to a reduction of the as-milled grain size. After sintering, SEM study confirmed a segregation of the initial HEA phase directly related to the melting temperature of the elements. Three melting temperature groups were described (Cr, FeCoNi and Mn) and they agree with the observation in the elemental mapping study. The presence of Al favored the segregation of Cr. 

Junio, 2018 | DOI: 10.1016/j.jallcom.2018.03.358

Heteroatom framework distribution and layer charge of sodium Taeniolite

Perdigon, AC; Pesquera, C; Cota, A; Osuna, FJ; Pavon, E; Alba, MD
Applied Clay Science, 158 (


The most advanced applications of clays depend crucially on their hydration state and swelling is probably the most important feature of expandable 2:1 layered silicate. Sodium Taeniolite, Na-TAE, a swelling trioctahedral fluormica, has been synthesized and studied using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and infrared and solid state NMR spectroscopies. The results indicated the formation of a swelling 2:1 phyllosilicate with actual layer charge lower than the nominal one. Herein, a new heteroatom distribution and more accurate composition could be deduced.

Junio, 2018 | DOI: 10.1016/j.clay.2018.03.036