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Scientific Papers in SCI



2022


Materiales de Diseño para la Energía y Medioambiente

Transparency of polymeric food packaging materials

Guzman-Puyol, Susana; Benitez, Jose J; Heredia-Guerrero, Jose A
Food Research International, 161 (2022) 111792

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Transparency is a very important technical parameter to evaluate and validate certain food packaging materials. In the recent scientific literature, several methods (i.e. transmittance, opacity, haze, and absorbance) have been used and such variety hinders a direct comparison of results from different authors. In this Review, we describe and discuss the most widely employed methods to measure transparency, with special emphasis on two main parameters: transmittance and opacity. Moreover, a comparison of the different techniques is addressed and the typical values of transmittance and opacity of common transparent food packaging materials are provided. Our current opinion is that transparency should be expressed as transmittance in the visible range due to both the quickness and easiness of the measurement and the standardization of data. This information should be accompanied by the thickness value and a graphical image of the analysed samples for a useful and complete characterization.


November, 2022 | DOI: 10.1016/j.foodres.2022.111792

Fotocatálisis Heterogénea: Aplicaciones

Effective photocatalytic conversion of formic acid using iron, copper and sulphate doped TiO2

Zouheir, M; Tanji, K; Navío, JA; Hidalgo, MC; Jaramillo-Paez, CA; Kherbeche, A
Journal of Central South University, 29 (2022) 3592-3607

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In this paper, the combined addition of copper or iron and sulphate ions onto TiO2 prepared by a simple sol-gel method is studied for formic acid photocatalytic conversion. A wide structural and morphological characterization of the different photocatalysts was performed by X-ray diffraction (XRD), N2-physisorption for BET surface area measurements, scanning and transmission electronic microscopies (SEM and TEM), UV-Vis diffuse spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS), in order to correlate the physico-chemical properties of the materials to their photocatalytic efficiencies for formic acid oxidation. Results have shown important differences among the catalysts depending on the metal added. Sulphated TiO2/Cu (1%Cu) was the best photocatalyst obtaining about 100% formic acid conversion in only 5 min. The appropriate physico-chemical features of this photocatalyst, given by the addition of combined copper and sulphate ions, explain its excellence in photocatalytic reaction.


November, 2022 | DOI: 10.1007/s11771-022-5172-9

Monitoring the Simultaneous Implantation of Ti and Tb Cations to a Sacrificial Template and the Sol-Gel Synthesis of Tb-Doped TiO2 (Anatase) Hollow Spheres and Their Transition to Rutile Phase

Colomer, MT; Vattier, F
International Journal of Molecular Sciences, 23 (2022) 13162

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Tb-doped TiO2 (anatase) micro-hollow spheres (HSs) with nano-shells, in the range 0.00-3.00 at.% Tb, were successfully synthesized by a simultaneous chemical implantation route of both Ti and Tb cations from chlorides to a poly-styrene (PST)-co-poly-divinyl benzene (PDVB) sacrificial template, followed by controlled hydrolysis and polycondensation reactions. After water addition to the mixture of the precursors with the template, a decrease in the intensity and a shift to lower wavenumbers of the C=O absorption band in the IR spectra can indicate not only the anchoring of Ti and Tb ions to the carbonyl group of the template but also the hydrolysis of the implanted precursors. This latter process can involve a proton attack on the Ti-Cl, Tb-Cl and C=O bonds, the occupation of a vacant site by a water molecule, and then the dissociation of the dangling Ti-Cl, Tb-Cl ligands and C=O bonds. It gives rise to Ti1-xTbx[(OH)(4-u)Cl-v]@PST-PDVB and Ti1-xTbx[(OH)(4-y)]@PST-PDVB complexes (x = 0.00, 0.0012, 0.0170 and 0.030). Finally, polycondensation of these species leads to Ti1-xTbxO2-w'@PST-PDVB compounds. After subsequent thermal removal at 550 degrees C of the template, the IR bands of the core (template) totally vanished and new bands were observed in the 400-900 cm(-1) region which can be attributed to the metalloxane bondings (M-O, M'-O, M-O-M, M-O-M' and/or M'-O-M', being M and M' = Ti and Tb, respectively, i.e., mainly vibration modes of anatase). Then, micron-sized HSs of TiO2 and Tb-doped-TiO2 (anatase) were obtained with nano-shells according to field emission gun scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) observations. Furthermore, X-ray photoelectron spectroscopy (XPS) measurements confirmed the presence of Tb4+ (38.5 and 41.2% for 1.70 and 3.00 at.% Tb, respectively) in addition to Tb3+ in the resulting HSs, with increasing Tb4+ content with both Tb doping and higher calcination temperatures. Then, these HSs can be considered as rare earth (RE) co-doped systems, at least for 1.70 and 3.00 at.% Tb contents being the transition to rutile phase favored by Tb doping for those compositions. Finally, diffusion of Tb from the inner parts to the surface of the HSs with the calcination treatments was also observed by XPS.


November, 2022 | DOI: 10.3390/ijms232113162

Materiales Nanoestructurados y Microestructura

Morphologically diverse CaCO3 microparticles and their incorporation into recycled cellulose for circular economy

Guerra-Garces, J; Garcia-Negrete, CA; Pastor-Sierra, K; Arteaga, GC; Barrera-Vargas, M; de Haro, MJ; Fernandez, A
Materials Today Sustainability, 19 (2022) 100166

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The main raw material for manufacture of paper is cellulose fibers that can be virgin or recycled. Globally, 70% of the Tetra Pak packages sold are not recycled and remain as unused wastes. Therefore, the development of alternatives to promote greater recycling and sustainable use of these packages is of great interest. In this study, the formation of precipitated calcium carbonates (PCC) in the presence of carboxymethyl cellulose (CMC) is studied at different temperatures, and the morphologically diverse particles obtained are explored as filler for composites based on cellulosic fibers recovered from Tetra Pak containers. It was found that the addition of filler does not lead to deterioration of either tensile strength or thermal and stability of the obtained composite samples. Results also suggest that the morphological diversity of the filler contributes to a more efficient filling of the interfibrillar spaces of cellulosic fibers and, in turn, to the fiber and filler compatibility.


November, 2022 | DOI: 10.1016/j.mtsust.2022.100166

Materiales Ópticos Multifuncionales

Enhanced red-UC luminescence through Ce3+ co-doping in NaBiF4:Yb3+/Ho3+(Er3+)/Ce3+ phosphors prepared by ultrafast coprecipitation approach

Giordano, L; Du, H; Castaing, V; Luan, F; Guo, D; Viana, B
Optical Materials X, 16 (2022) 100199

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Series of Yb3+/Ho3+(Er3+)/Ce3+ co-doped NaBiF4 phosphors were synthesized through an ultrafast co-precipitation reaction technique at room temperature. The effect of the Ce3+ ions on the crystal structure and upconversion (UC) luminescence properties of the studied samples were investigated in detail. FTIR and XPS demonstrated the pre-formation of NaBiF4 and the introduction of Yb3+, Ho3+, Er3+ and Ce3+ all as dopants in the host materials. Under 980 nm excitation, NaBiF4:Yb3+,Ho3+(Er3+),Ce3+performed the characteristic emission of the activator ion, and the introduction of Ce3+ did not change the emission wavelengths, only the relative intensities. Due to partial good energy overlap when 2F7/2 Ce3+ manifold is populated, raising Ce3+ ions concentration enhanced the red UC emission versus green UC emission but also lead to significant decrease in the average lifetimes of all monitored emissions for Ho3+ and Er3+. These lifetime decreases are explained by the energy loss in non-radiative pathways after the introduction of Ce3+. In addition, the green to yellow color emission change through addition of Ce3+ was explored in NaBiF4: Yb3+,Ho3+,Ce3+ to propose a novel application in two-level anti-counterfeiting.


October, 2022 | DOI: 10.1016/j.omx.2022.100199

 

 

 

 

 

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