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Scientific Papers in SCI

2018


Selective CO methanation with structured RuO2/Al2O3 catalysts


Munoz-Murillo, A; Martinez, LM; Dominguez, MI; Odriozola, JA; Centeno, MA
Applied Catalysis B-Environmental, 236 (2018) 420-427

ABSTRACT

Active and selective structured RuO2/Al2O3 catalysts for CO methanation using a flow simulating CO2-rich reformate gases from WGS and PROX units (H-2 excess, CO2 presence and 300 ppm CO concentration) were prepared. Both, the RuO2/Al2O3 powder and the slurry prepared from it for its structuration by washcoating of the metallic micromonolithic structure, were also active and selective. Both the slurry (S-RuAl) and micro monoliths (M-RuAl) were able to completely and selectively methanate CO at much lower temperatures than the parent RuAI powder. The optimal working temperature in which the CO conversion is maximum and the CO2 conversion is minimized was determined to be from 149 degrees C to 239 degrees C for S-RuAl and from 165 degrees C to 232 degrees C for M-RuAl, whilst it was from 217 degrees C to 226 degrees C for RuAI powder. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity for CO methanation among the considered catalysts can be related with modifications in the surface particle size of ruthenium and its reducibility. These were ascribed to the metallic substrate, the presence of PVA and colloidal alumina in the slurry preparation, the aqueous and acidic media and the thermal treatment used, resulting in a more active and selective catalysts than the parent powder.


November, 2018 | DOI: 10.1016/j.apcatb.2018.05.020

Photocatalytic H2 production from glycerol aqueous solutions over fluorinated Pt-TiO2 with high {001} facet exposure


V. Vaiano; M.A. Lara; G. Iervolino; M. Matarangolo; J.A. Navío; M.C. Hidalgo
Journal of Photochemistry and Photobiology A-Chemistry, 365 (2018) 52-59

ABSTRACT

An optimized fluorinated TiO2 catalyst with high {001} facet exposure loaded with platinum (TiO2-PtFAC) was tested in the photocatalytic hydrogen production from glycerol solution under UV light irradiation. The samples were synthesized by direct hydrothermal treatment starting from two different types of precursors that are titanium tetraisopropoxide (I) or titanium butoxide (B), while platinisation was performed by photodeposition method. The obtained catalysts were characterised by different techniques (XRD, FESEM, TEM, BET, UV–vis DRS, XRF and XPS) and the results evidenced that anatase is the only crystalline phase present in all TiO2 samples. The morphology of the samples was seen as rectangular platelets particles where Pt particles were was observed all over the surface. The presence of Pt and F in the platinised samples was also confirmed by XRF and XPS analysis. The photocatalytic results have shown that the presence of Pt on TiO2{001}facet surface remarkably enhanced the hydrogen production from aqueous solution at 5 wt % of glycerol. Comparing the results obtained from the photocatalysts prepared by the two different precursors, it was found that the best performances in terms of H2 production was achieved with TiO2-PtFAC(I) (about 13 mmol L−1 after 4 h of irradiation time), while the H2 production was lower for TiO2-PtFAC(B) (about 9 mmol L−1 after 4 h of irradiation time). The effect of the operating conditions using TiO2-PtFAC(I) evidenced that the highest H2 production was obtained with a photocatalyst dosage equal to 1.5 g L−1, initial glycerol concentration at 5 wt% and a pH value equal to 7. Finally, a photocatalytic test was also performed on glycerol solution prepared with a real water matrix. Despite the presence of ions scavengers (chlorides and carbonates) in solution, TiO2-PtFAC(I) was able to reach a photocatalytic H2production of about 6 mmol L−1 after 4 h of UV light irradiation.


October, 2018 | DOI: 10.1016/j.jphotochem.2018.07.032

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

ABSTRACT

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.


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

A comprehensive and in-depth analysis of the synthesis of advanced adsorbent materials


Osuna, FJ; Cota, A; Pavon, E; Alba, MD
Journal of Cleaner Production, 194 (2018) 665-672

ABSTRACT

Na-Mica-4, a synthetic fluorophlogopite, is an attractive adsorbent. However, the synthesis at large scale demands an economically prized, feasible scalable and sustainable synthesis method, which requires a deep knowledge of the influence of each synthesis step. A set of Na-Mica-4 were synthesized by methods that had one synthesis parameter as variable. The purity, crystallinity and heteroatoms distribution were analysed thorough X-ray diffraction and nuclear magnetic resonance. The results shed a light on the main factors for the design of the final product and indicated that an environmental friendship synthesis could be possible. 


September, 2018 | DOI: 10.1016/j.jclepro.2018.05.179

Performance improvement in olive stone's combustion from a previous carbonization transformation


Gomez-Martin, A; Chacartegui, R; Ramirez-Rico, J; Martinez-Fernandez, J
Fuel, 228 (2018) 254-262

ABSTRACT

Under the framework of circular economy, agricultural wastes are an interesting carbon-based feedstock for thermal energy and power generation. Their use could extend the availability of biomass-based fuel and, at the same time, would reduce negative environmental effects. However, depending on the residues' characteristics, their direct combustion in boilers presents some challenges which could be overcome with a carbonization pretreatment. In this paper, the main mechanisms of thermochemical transformation of an abundant agricultural waste, olive stone, into biochar products via slow carbonization are analyzed, with emphasis on the effect of peak carbonization temperature. Thermogravimetric and differential scanning calorimetry analysis are used to evaluate the performance of the resulting biochars compared to raw olive stone in combustion processes and to assess the correlation between the peak carbonization temperature and compositional and fuel properties. Results show that with a prior treatment up to an optimum temperature of 800 degrees C the energy density is increased up to three times compared to the raw material. These findings suggest that carbonization of olive stones reduces the barriers to their direct use in current biomass boiler technology.


September, 2018 | DOI: 10.1016/j.fuel.2018.04.127

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


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

ABSTRACT

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.


September, 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

ABSTRACT

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.


September, 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

ABSTRACT

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.


September, 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

ABSTRACT

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.


August, 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

ABSTRACT

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.


August, 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

ABSTRACT

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.


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

Synthesis and characterization of SiC/Si3N4 composites from rice husks


Real, C; Cordoba, JM; Alcala, MD
Ceramics International, 44 (2018) 14645-14651

ABSTRACT

SiC-Si3N4 composites have been obtained by carbothermal reduction of rice husk under a nitrogen-argon atmosphere at 1450 degrees C, which is a lower temperature than those used by other authors. On the other hand, tailoring the argon/nitrogen ratio led to the obtained of SiC-Si3N4 composites across the whole range of compositions. Phosphoric acid treatment permited the synthesis of the composite without a pyrolysis step. The final products were characterized by X-ray diffractometry, IR spectroscopy and scanning electron microscopy.


August, 2018 | DOI: 10.1016/j.ceramint.2018.05.090

Electrical conduction mechanisms in graphene nanoplatelet/yttria tetragonal zirconia composites


Poyato, R; Osuna, J; Morales-Rodriguez, A; Gallardo-Lopez, A
Ceramics International, 44 (2018) 14610-14616

ABSTRACT

Yttria tetragonal zirconia polycrystalline (3YTZP) ceramic composites with 5, 10 and 20 vol% graphene nano-platelets (GNPs) were prepared by spark plasma sintering (SPS) and their electrical conductivity as a function of temperature was characterized. The composites exhibit anisotropic microstructures so the electrical conductivity studies were carried out in two directions: perpendicular (sigma(perpendicular to)) and parallel (sigma(parallel to)) to the SPS pressing axis. The composites with 5 and 10 GNP vol% showed high electrical anisotropy, whereas the composite with 20 GNP vol % exhibited nearly isotropic electrical behavior. sigma(perpendicular to) shows metallic-type behavior in the composites with 10 and 20 vol% GNP revealing that charge transport takes place through defect-free GNPs. For the composite with 5 vol % GNP the observed semiconductor-type behavior was explained by a two dimensional variable range hopping mechanism. sigma(parallel to)shows metallic-type conductivity in the composite with 20 GNP vol% and positive d sigma(parallel to)/dT slope in the composites with 5 and 10 GNP vol%.


August, 2018 | DOI: 10.1016/j.ceramint.2018.05.082

Mechanochemical synthesis, structural, magnetic, optical and electrooptical properties of CuFeS2 nanoparticles


Dutkova, E; Bujnakova, Z; Kovac, J; Skorvanek, I; Sayagues, MJ; Zorkovska, A; Kovac, J; Balaz, P
Advanced Powder Technology, 29 (2018) 1820-1826

ABSTRACT

The rapid mechanochemical synthesis of nanocrystalline CuFeS2 particles prepared by high-energy milling for 60 min in a planetary mill from copper, iron and sulphur elements is reported. The CuFeS2 nanoparticles crystallize in tetragonal structure with mean crystallite size of about 38 ± 1 nm determined by XRD analysis. HRTEM study also revealed the presence of nanocrystals with the size of 5–30 nm with the tendency to form agglomerates. The Raman spectrum confirms the chalcopyrite structure. Low temperature magnetic data for CuFeS2 support the coexistence of antiferromagnetic and paramagnetic spin structure. Moreover, the hysteresis loops taken at temperatures from 5 K to 300 K revealed a presence of very small amount of ferromagnetic phase, which seems to be associated with the non-consumed elemental Fe in as-prepared nanoparticles. The optical band gap of CuFeS2nanoparticles has been detected to be 1.05 eV, larger than band gap of the bulk material. The wider gap possibly resulted from the nano-size effect. Photoresponses of CuFeS2nanoparticles were confirmed by I-V measurements under dark and light illumination. It was demonstrated that mechanochemical synthesis can be successfully employed in the one step preparation of nanocrystalline CuFeS2 with good structural, magnetic, optical and electrooptical properties.


August, 2018 | DOI: 10.1016/j.apt.2018.04.018

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

ABSTRACT

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.


July, 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

ABSTRACT

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.


July, 2018 | DOI: 10.1111/gcb.14276

Hydrodeoxygenation of vanillin over carbon supported metal catalysts


Santos, JL; Alda-Onggar, M; Fedorov, V; Peurla, M; Eranen, K; Maki-Arvela, P; Centeno, MA; Murzin, DY
Applied Catalysis A-General, 561 (2018) 137-149

ABSTRACT

Different carbon supported metal catalysts were synthesized, and characterized with various physico-chemical methods and tested in vanillin hydrodeoxygenation under 30 bar total pressure in water as a solvent at 100 degrees C. The catalysts exhibited high specific surface area and the metal dispersion decreased in following order: Pt/ C > Pd/C > Au/C > Rh/C > Ru/C. The most active catalyst was Pd/C followed by Ru/C. Vanillin hydrodeoxygenation proceeded via hydrogenation forming vanillyl alcohol further to its hydrogenolysis forming p-creosol. Both hydrogenation and hydrogenolysis were promoted by Pd/C, which exhibited rather high dispersion. The highest selectivity to p-creosol, 95% at complete vanillin conversion, was obtained with Pd/C. Kinetic modelling of vanillyl alcohol selectivity as a function of vanillin conversion was performed.


July, 2018 | DOI: 10.1016/j.apcata.2018.05.010

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

ABSTRACT

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.


July, 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

ABSTRACT

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.


July, 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

ABSTRACT

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.


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

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