Idoneidad de las podas de naranjo como materia prima para la producción de pasta celulósica para diversos usos

En una fábrica integral de papel existen dos procesos: el de obtención de pasta y el de formación de la hoja de papel. El proceso de obtención de pasta consiste en la transformación de las materias primas en fibras celulósicas aisladas en una suspensión acuosa diluida, mediante la separación de la lignina, que es el agente que, a modo de cemento, aglomera las fibras y fija su posición. En el proceso de formación de la hoja de papel, la pasta, tratada convenientemente para desarrollar algunas propiedades características, se somete a operaciones que tienen por finalidad extenderla en forma de láminas y eliminar la mayor parte de su humedad. En la actualidad, la producción de pasta celulósica para papel u otros usos se encuentra con el problema del abastecimiento de materias primas clásicas (maderas frondosas y coníferas) que son escasas en diversas regiones del planeta. Por ello se está investigando la posibilidad de utilizar materias primas alternativas como pueden ser los residuos agrícolas, al mismo tiempo con la finalidad de dotarlos de un valor que como residuos no tienen, evitando además perjuicios económicos para las empresas agrícolas que han de deshacerse de ellos; por otra parte se consigue un beneficio ecológico al eliminar fuentes de contaminación. En Andalucía se producen grandes cantidades de residuos agrícolas, como las podas de naranjo, con producciones importantes y concentradas en ciertas zonas geográficas. Desde hace mucho tiempo, en la producción de pastas celulósicas, sólo la fracción principal de las materias primas, constituida por la madera de troncos y ramas (la más rica en α-celulosa), es aprovechada para tal fin, desechándose la fracción residual (mezcla de tallos y ramas de pequeño tamaño y hojas); pero además, de la fracción principal sólo se aprovecha la α- celulosa, desaprovechándose dos importantes componentes presentes en los materiales lignocelulósicos: la hemicelulosa y la lignina. Un intento de conseguir un aprovechamiento integral de los recursos naturales sugiere la necesidad de implantar nuevas líneas de producción de subproductos procedentes de la fabricación de pasta celulósica. Así, tras unas operaciones de acondicionamiento de las materias primas (descortezado, desmedulado, astillado, etc.), un modo de alcanzar el aprovechamiento integral de las mismas puede consistir en la separación de dos fracciones: una principal y otra residual. La primera puede someterse a un tratamiento hidrotérmico para degradar la hemicelulosa, cuyos productos de degradación pasan a una fracción líquida, de la que pueden obtenerse productos de alto valor añadido (aditivos alimentarios, fármacos, etanol, xilitol, furfural, etc.); posteriormente, la fracción sólida resultante del tratamiento hidrotérmico se somete a un pasteado adecuado, con la finalidad de separar la celulosa (empleada para la fabricación de pasta para papel u otros usos) de la lignina, que puede emplearse para la producción de diversos productos con elevado valor comercial, como resinas, poliuretanos, acrilatos, epóxidos, composites, etc. Por otra parte, la fracción residual de la materia prima puede utilizarse para la producción de energía mediante los procesos de combustión, pirolisis o gasificación. La empresa ECOPAPEL, S.L. de Écija (Sevilla) está muy interesada en la producción de pasta a partir de residuos agrícolas para diversos usos, y en el..

Chemical precipitation of nickel nanoparticles on Ti(C,N) suspensions focused on cermet processing

Ti(C,N)-based cermets are currently used in high speed cutting tools industry due to its high thermal stability. In previous works, Fe was proposed as metal matrix, however the use of iron as continuous matrix strongly affects the processing due to the low wetting capability of molten Fe with the reinforcement phase, Ti(C,N). To solve this problem, the use of alloys such as FeNi has been proposed, where Ni improves the wettability between the ceramic and the metal phases. This work proposes a bottom-up approach to build the cermet microstructure through the synthesis of metal nanoparticles (NPs) on the surface of Ti(C,N) micrometric particles, creating Ti(C,N)-Ni core-shell structures. For that purpose, the in-situ synthesis of Ni NPs through the chemical reduction of a Ni precursor onto the surface of micrometric Ti(C,N) particles, previously stabilized in an aqueous suspension, was proposed. Core-shell structures were characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), high resolution scanning electron microscopy (HRTEM), energy-dispersive X-Ray spectroscopy (EDX) and Raman Spectroscopy.The authors acknowledge the support of the projects S2013/MIT 2862 MAT2015 70780 C4 1 P and MAT2015 70780 C4 2 P. M. De Dios acknowledges MINECO through the grant BES 2013 065760 and Dr. Z González acknowledges to MINECO through the grant PTQ 13 05985

Development of lessons on chemical and biological reactors in Moodle platform

En este proyecto docente se han desarrollado una serie de actividades académicamente dirigidas dedicadas a los reactores químicos y biológicos, en concreto, se ha empleado una herramienta denominada lección que se encuentra disponible a través de la plataforma virtual Moodle, dichas lecciones se basan en una serie de ventanas secuenciales que permiten profundizar en todos los conceptos fundamentales de los reactores químicos y/o biológicos y, a través de diversas cuestiones complementarias sobre el tema, incluidas durante el desarrollo de dicha lección, permite al alumno realizar un aprendizaje más activo que favorece la consolidación de los conceptos de forma gradual. Previo al estudio de los reactores químicos y/o biológicos es necesario tener en cuenta diversos aspectos químicos, físicos, matemáticos, biológicos e ingenieriles que han de considerarse para desarrollar los aspectos fundamentales básicos para poder alcanzar dicho objetivo y se pretende facilitar esta labor al alumnado con el empleo de las lecciones elaboradas. Previamente a la elaboración de las lecciones se ha realizado una importante labor de preparación y síntesis de toda la información, posteriormente se han desarrollado diferentes lecciones para los conceptos tratados en cada uno de los temas implicados en la elaboración de este proyecto docente y tras una profunda revisión se han puesto a disposición de los alumnos.In this teaching project have developed a series of academic activities devoted to the chemical and biological reactors, in particular, it has been using a tool called lesson which is available through the Moodle virtual platform, these lessons are based on a series of sequential windows allowing to delve into all the fundamental concepts of chemical and/or biological reactors and through various complementary on the theme, including issues during the development of this lesson, students perform a more active learning that promotes the consolidation of concepts gradually. Prior to the study of chemical reactors and/or biological is necessary to take account of various chemical, physical, mathematical, biological and engineering aspects that are to be considered to develop the basic fundamentals to achieve the aim and is intended to facilitate this work to the students with the use of elaborate lessons. Important preparation work has been prior to the preparation of the lessons and synthesis of information, have subsequently developed different lessons for the concepts dealt with in each of the issues involved in the development of this educational project and after a thorough review have been available to the students

Understanding the effects of different microstructural contributions in the electrochemical response of Nickel-based semiconductor electrodes with 3D hierarchical networks shapes

[EN] It is well known that exposed surface area, nanoparticles connectivity and its consolidation level in a nanostructure are key points in the enhancement of the electrochemical performance in energy storage devices. The design and optimization of different electrodes with specific microarchitectures (based on the arrangement manipulation of NiO nanoplatelets, used as building blocks), has allowed distinguishing the effects of each microstructural contribution in their final electrochemical responses, overpassing thermal and mechanical mismatches between the semiconductor ceramic structure and the metallic collector. In all cases, the same electroactive material and the same coating technique were used, preventing the interference of secondary phenomena in the EIS studies, and allowing argue over the contribution of the microstructural features incorporated to the electrode (nature and shape of the collector, degree of sintering and consolidation of the ceramic microstructure, incorporation of non-noble metallic nanoparticles and the macro/meso/microposity effect) in the effective profiting of the Faradaic phenomena observed during their cycling. The modification of the Ni-based electrodes allows understanding how microstructural features infer the electron transport and the ion diffusion through the consolidated structure. The EIS analysis proves that the design of the porous hierarchical network of our semiconductors electrodes resulted in a good rate capability (with capacitance values of 1000 F g¿1 or 500 C g¿1), exhibiting a relaxation time constant (¿0 = 18 ms), while a slight increase of the charge-transfer resistance (Rct = 3.65¿) is negligible if the exposed surface is high enough to maintain a high ion transport. The inclusion of non-noble nanoparticles, such as Ni NPs, in the NiO semiconductor microstructure and the optimum deposited mass and sintering treatment create a metal-ceramic electrode that enhances both the charge transfer resistance (1.55 ¿) showing relaxation time in the range (¿0 = 11 ms) and maintaining an excellent capacitive behavior (750 F g¿1 or 375C g¿1) at quick charge/discharge rate.2018/NMT-4411(Comunidad de Madrid, Spain) and MAT2015-70780-C4-1(MINECO/FEDER, Spain). J. Yus acknowledges the Comunidad de Madrid for the support from the Youth Employment Initiative,CAMPD17_ICV_002. Z. Gonzalez acknowledges the Postdoctoral Fellowship: IJCI-2016-28538 (MINECO, Spain

Core-shell Ni-Ti(C,N) structures fabricated by precipitation of based-Ni nanoparticles on TiCN suspensions

Proceedings of: European Congress and Exhibition on Powder Metallurgy (Euro PM2015 Congress & Exhibition), Reims (France), 4-7 September 2015Ti(C,N)-based cermets are currently used in high-speed cutting tools industry due to their high thermal stability. In previous works, Fe was proposed as metal matrix, however the use of iron as continuous matrix strongly affects the processing due to the low wetting capability of molten Fe with the reinforcement phase, Ti(C,N). To solve this problem the use of alloys such as FeNi has been proposed, where Ni improves the wettability between the ceramic and the metal phases. This work proposes a bottom-up approach to build the cermet microstructure through the synthesis of metal nanoparticles on the surface of Ti(C,N) micrometric particles, creating core-shell Ti(C,N)-Ni structures. For that purpose, synthesis parameters to obtain Ni nanoparticles were optimized and then, a one-pot synthesis procedure was tested to obtain core-shell Ti(C,N)-Ni particles by the chemical precipitation of Ni nanoparticles onto the surface of micronic Ti(C,N) particles previously stabilized in an aqueous suspension. Nickel nanoparticles and subsequent core-shell were characterized by measuring the particle size by Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), field emission scanning electron microscopy (FE-SEM).The authors acknowledge the support of the projects S2013/MIT-2862 and MAT2012-38650-02-01, MAT2012-38650-C02-02. M. de Dios acknowledges MINECO through the grant FPI-2013 and Dr. Z González acknowledges to MINECO through the grant PTQ-13-05985

Exploitation of Lignocellulose Fiber-Based Biotemplates to Improve the Performance of an Immobilized TiO2 Photocatalyst

The performance of an immobilized photocatalyst has been successfully improved by colloidal processing of a heterostructure composed by TiO2 nanoparticles and lignocellulose nanofibers (LCNFs) obtained from biomass residues. The incorporation of 4 wt.% of biotemplate to the formulation increased the degradation rate and reduced the operating time to remove the 100% of methyl orange of a liquid solution. The reaction rate constant (k = 0.29–0.45 h−1) of the prepared photocatalytic coatings (using commercial particles and templates obtained from natural-derived resources) are competitive with other pure TiO2 materials (no composites), which were prepared through more complex methodologies. The optimization stages of deposition and sintering processes allowed us to obtain homogeneous and crack-free microstructures with controlled thickness and mass values ranging from 3 to 12 µm and 0.9 to 5.6 mg, respectively. The variation of the microstructures was achieved by varying the amount of LCNF in the formulated suspensions. The versatility of the proposed methodology would allow for implementation over the internal surface of photocatalytic reactors or as a photocatalytic layer of their membranes. In addition, the processing strategy could be applied to immobilize other synthetized semiconductors with higher intrinsic photocatalysis properties.This research was supported by the projects S2018/NMT-4411 (Comunidad de Madrid) and PID2019-106631GB-C42 (MINECO/FEDER). Z. Gonzalez acknowledges the Spanish Ministry of Economy and Competitiveness for the Postdoctoral Fellowship: IJCI-2016-28538.This work was supported by FCT-Fundação para a Ciência e a Tecnologia (project PEst-OE/QUI/UI0674/2019, CQM, Portuguese government funds), through the Madeira 14–20 Program, project PROEQUIPRAM Reforço do Investimento em Equipamentos e Infraestruturas Científicas na RAM (M1420-01-0145-FEDER-000008) by ARDITI-Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação, through project M1420-01-0145-FEDER-000005—Centro de Química da Madeira CQM + (Madeira 14–20). SM was supported by the postdoctoral fellowship granted by ARDITI CQM + project (ARDITI-CQM/2017/008-PDG). RP was supported by an FCT postdoctoral grant (SFRH/BPD/97387/2013).Peer reviewedPeer reviewe

Electrophoretic deposition of RGO-NiO core-shell nanostructures driven by heterocoagulation method with high electrochemical performance

A heterocoagulation route is proposed to prepare Reduced Graphene Oxide-Nickel Oxide (RGO/NiO) hybrid structures for their application as supercapacitor electrodes. The RGO intercalation among the NiO nanoplatelets was carried out by electrostatic interactions of the synthetized particles which were previously dispersed and stabilized in aqueous media to improve the assembly between both materials forming core-shell structures. The electrophoretic deposition (EPD) was used to shape the composite onto 3D collector (Ni foams) controlling their growth and homogeneity. Electrodes were thermal treated at 325 °C during 1 h to improve the electrochemical response since the formation of ceramic necks among NiO semiconductor nanoparticles preserves the microstructural integrity to enhance their connectivity avoiding the employment of binders, while RGO contributes with the electrochemical double layer effect to step up the specific capacitance by reducing the charge transfer resistance. FESEM results confirmed that RGO nanosheets were full-covered by the NiO nanoplatelets and suggested that ∼1 mg of the electroactive composite homogeneously covers the Ni foam and it is the optimum among of electroactive material to avoid microstructural defects that produce ohmic drops limiting the capacitance. The electrochemical characterization of the resulting binder-free RGO/NiO electrodes was compared with the bare-NiO electrode. The hybrid composite exhibited excellent performance with a high specific capacitance of 940 FThe authors thank the support to the projects S2018/NMT-4411 (Comunidad de Madrid) and MAT2015-70780-C4-1 (MINECO/FEDER). J. Yus acknowledges the Comunidad de Madrid for the support from the Youth Employment Initiative, CAMPD17_ICV_002. Z. Gonzalez acknowledges the Postdoctoral Fellowship: IJCI-2016-28538.Peer Reviewe

Electrophoretic deposition of Ni(OH)2 nanoplatelets modified by polyelectrolyte multilayers: Study of the coatings formation in a laminar flow cell

The electrophoretic deposition (EPD) of semiconductor ceramic nanoplatelets functionalized by self-assembled polyelectrolyte multilayers has been investigated. The influence of particle surface modification in the packing of the nanostructured film on a nickel cathode has been determined for different electrical conditions. A polymer multilayer shell has been fashioned onto β-Ni(OH) nanoplatelets surfaces by alternating the adsorption of Polyethylenimine (PEI) and Polyacrylic Acid (PAA). Two different core-shell systems with 1, 3 and 5 layers were considered using either linear or branched PEI as polycation to alternate with the anionic polyelectrolyte (PAA). The Layer by Layer, (LbL) build-up of polyanions and polycations was characterized both in terms of particle zeta potential measurements and in situ measurements of polyelectrolyte adsorption onto a flat substrate by optical fixed-angle reflectometry. The amount of polyelectrolyte required to build up each layer was determined from zeta potential measurements. Both data allowed the design of the in situ formation of the core-shell nanostructures as well as the shaping of the particulated coatings following the one-pot procedure, avoiding intermediate steps of drying or washing. The movement of the core-shell particles, their aggregation state and the coating growth during electrophoretic deposition were studied in situ using a laminar flow cell coupled to an optical microscope. The particle flux was calculated from the surface coverage of the cathode and compared to the values estimated by the EPD electrokinetic model, demonstrating the strong impact of the steric interactions between the core-shell particles in both the deposition rate of nanoplatelets and the coating morphology.The authors acknowledge the support to the European Ceramic Society through JECS 520 Trust funding. Also they acknowledge the support to the project S2013/MIT-2862 and 521 MAT2015-70780-C4-1.Peer Reviewe

Protective nature of nano-TiN coatings shaped by EPD on Ti substrates

The hardness and corrosion resistance of TiN coatings, processed by Electrophoretic Deposition (EPD) to cover polished and unpolished Ti substrates, have been evaluated. A deposition time of 5 min has been enough to obtain a cohesive layer of 7–8 μm in thickness. The coatings were thermally treated in vacuum atmosphere at 1200 °C for 1 h with heating and cooling rates of 5 °C min. The surfaces have been covered homogeneously optimizing the properties of the Ti substrates. Uniform and dense TiN coatings have been obtained onto polished substrates, while on unpolished Ti the nitrogen diffuses toward the substrate, moderately dissolving TiN coating. The nanohardness values of the polished samples have been increased from 2.8–4.8 GPa up to 6.5–8.5 GPa. Besides, the corrosion current density has been reduced more than one order of magnitude obtaining a protective efficiency of 82%. These values have been compared with other works in literature where authors used complex and costly processing techniques, demonstrating the strong impact of the colloidal processing over the specific properties of the material.The authors acknowledge the support to the projects S2013/MIT-2862 and MAT2015-70780-C4-1.Peer Reviewe

Electrochemical performance of pseudo-capacitor electrodes fabricated by Electrophoretic Deposition inducing Ni(OH)2 nanoplatelets agglomeration by Layer-by-Layer

The electrochemical behaviour of ceramic semiconductors not only depends on the characteristics of the electroactive material but also on the processing method, the nanoparticles arrangement and the consolidation degree of the formed microstructure. In this sense, the use of nanoparticles with plane morphologies (disc, platelets, etc.) results interesting due to the formation of conduction pathways produced as a consequence of their laminar structures. Electrophoretic Deposition (EPD) is a shaping methodology which allows achieving high degrees in nanoplatelets packing by controlling their alignment during the coating process specifically over 3D substrates. In this work, we have studied the effect of a moderate nanoplatelets agglomeration, by tuning their surfaces with a polyelectrolyte multilayer following a Layer-by-Layer (LbL) methodology and fixing the electric conditions of the EPD process. Overcoming the destructive effects of the full agglomeration of nanoplatelets, NiO films with a stable and extremely open macroporous structure were processed to coat Ni foams, improving the capacitive performance of pseudocapacitors leading to values of specific capacitances of 650 F/g. Results collected in this work also evidence that an efficient ordering and orientation of nanoplatelets in EPD mainly depends on tuning the suspension parameters (solid contents, conductivity, electrophoretic mobility, etc.) to avoid the massive flux and interactions among interparticles and electro-hydrodynamic forces, as well as the interference of collateral electrode phenomena.The authors acknowledge the support of the project S2013/MIT-2862 and MAT2015-70780-C4-1 and Dr. Z Gonzalez acknowledges to JECS-TRUST fund contract 201481.Peer Reviewe