Sustainable Alternatives for the Development of Thermoset Composites with Low Environmental Impact

The current concerns of both society and the materials industries about the environmental impact of thermoset composites, as well as new legislation, have led the scientific sector to search for more sustainable alternatives to reduce the environmental impact of thermoset composites. Until now, to a large extent, sustainable reinforcements have been used to manufacture more sustainable composites and thus contribute to the reduction of pollutants. However, in recent years, new alternatives have been developed, such as thermosetting resins with bio-based content and/or systems such as recyclable amines and vitrimers that enable recycling/reuse. Throughout this review, some new bio-based thermoset systems as well as new recyclable systems and sustainable reinforcements are described, and a brief overview of the biocomposites market and its impact is shown. By way of conclusion, it should be noted that although significant improvements have been achieved, other alternatives ought to be researched.This research was funded by the Provincial Council of Bizkaia by its Technology Transfer Program 2021 (BIOKONP Project, Reference 6/12/TT/2021/) and by Department of Economic Development and Infrastructures of The Basque Government by its ELKARTEK 2022 Program (FRONTIERS Project, Reference KK-2022/00109)

Insights into the Nature of the Active Sites of Pt-WOx/Al2O3 Catalysts for Glycerol Hydrogenolysis into 1,3-Propanediol

The chemo-selective hydrogenolysis of secondary hydroxyls is an important reaction for the production of biomass-derived α,ω-diols. This is the case for 1,3-propanediol production from glycerol. Supported Pt-WOx materials are effective catalysts for this transformation, and their activity is often related to the tungsten surface density and Brönsted acidity, although there are discrepancies in this regard. In this work, a series of Pt-WOx/γ-Al2O3 catalysts were prepared by modifying the pH of the solutions used in the active metal impregnation step. The activity–structure relationships, together with the results from the addition of in situ titrants, i.e., 2,6-di-tert-butyl-pyridine or pyridine, helped in elucidating the nature of the bifunctional active sites for the selective production of 1,3-propanediol.This work was supported by the University of the Basque Country (UPV/EHU), European Union, through the European Regional Development Fund (ERDF) (Spanish MICIN Project: RTI2018-094918-BC43), and the Basque Government (IT993-16). Clara Jarauta Cordoba acknowledges financial support from the Spanish Government (BES-2014-069165 and EEBB-I-18-13018)

Integrated Environmental and Exergoeconomic Analysis of Biomass-Derived Maleic Anhydride

Life cycle analysis and exergy analysis are applied to compare the production of maleic anhydride from different feedstock, both biomass- and petrochemical-derived raw materials, in order to evaluate the sustainability of alternative biorefinery processes to conventional routes. The considered processes involve two options: gas and aqueous phase furfural oxidation with oxygen (air) and hydrogen peroxide as oxidants, respectively, considered as sustainable technologies because of the use of renewable feedstock. Conventional routes, used as benchmarks, include the current production processes using benzene or butane as raw materials. The results show that the aqueous phase process is far from being viable from an energy and environmental point of view due to the high exergy destruction and the use of H2O7 as oxidant (whose production entails important environmental drawbacks). On the contrary, the gas phase oxidation of furfural shows competitive results with petrochemical technologies. Nevertheless, the major environmental drawback of the new furfural-to-maleic anhydride production processes is detected on the environmental profile of the starting raw material. The results suggest that a better environmental footprint for maleic anhydride production in gas phase can be obtained if environmentally friendly furfural production technologies are used at the commercial scale.This research was funded by the Spanish Ministry of Science, Innovation and Universities (projects RTI2018-094918-B-C41, RTI2018-094918-B-C42, and RTI2018-094918-B-C43)

Oxidation of lignocellulosic platform molecules to value-added chemicals using heterogeneous catalytic technologies

Currently, much attention is being paid to the development of sustainable catalytic processes for the production of chemicals (biofuels, bioproducts, and so on) from lignocellulosic biomass. This minireview pursues to give an exhaustive overview about the heterogeneous catalytic technologies proposed for the oxidation of four key platform molecules (glucose, 5-hydroxymethylfurfural, furfural and levulinic acid) into important chemicals, such as gluconic acid and gluconates, glucaric and formic acids, 2-diformylfuran, 2,5-furandicarboxylic acid, maleic acid and anhydride, succinic acid, furanones, furoic acid, alkyl furoates, furan-2-acrolein, succinic acid, butanone and 3-hydroxypropanoic acid. The different mechanistic pathways will be highlighted, as well as the requirements in terms of catalytic sites and catalyst stability. The challenges and opportunities will be put forward for each type of oxidation process.Spanish Ministry of Science, Innovation and Universities (RTI2018-94918) and FEDER (European Union) funds. J. A. C. thanks University of Malaga for contracts of PhD incorporation

Modifying the magnetic response of magnetotactic bacteria: incorporation of Gd and Tb ions into the magnetosome structure

Magnetotactic bacteria Magnetospirillum gryphiswaldense MSR-1 biosynthesise chains of cube-octahedral magnetosomes, which are 40 nm magnetite high quality (Fe3O4) nanoparticles. The magnetic properties of these crystalline magnetite nanoparticles, which can be modified by the addition of other elements into the magnetosome structure (doping), are of prime interest in a plethora of applications, those related to cancer therapy being some of the most promising ones. Although previous studies have focused on transition metal elements, rare earth (RE) elements are very interesting as doping agents, both from a fundamental point of view (e.g. significant differences in ionic sizes) and for the potential applications, especially in biomedicine (e.g. magnetic resonance imaging and luminescence). In this work, we have investigated the impact of Gd and Tb on the magnetic properties of magnetosomes by using different complementary techniques. X-ray diffraction, transmission electron microscopy, and X-ray absorption near edge spectroscopy analyses have revealed that a small amount of RE ions, similar to 3-4%, incorporate into the Fe3O4 structure as Gd3+ and Tb3+ ions. The experimental magnetic characterisation has shown a clear Verwey transition for the RE-doped bacteria, located at T similar to 100 K, which is slightly below the one corresponding to the undoped ones (106 K). However, we report a decrease in the coercivity and remanence of the RE-doped bacteria. Simulations based on the Stoner-Wohlfarth model have allowed us to associate these changes in the magnetic response with a reduction of the magnetocrystalline (K-C) and, especially, the uniaxial (K-uni) anisotropies below the Verwey transition. In this way, K-uni reaches a value of 23 and 26 kJ m(-3) for the Gd- and Tb-doped bacteria, respectively, whilst a value of 37 kJ m(-3) is obtained for the undoped bacteria.This work was supported in part by the Spanish MCIN/AEI under Projects MAT2017-83631-C3-R and PID2020-115704RB-C33. The work of Elizabeth M. Jefremovas was supported by the "Concepci ' on Arenal Grant" awarded by Gobierno de Cantabria and Universidad de Cantabria. The work of Lourdes Marcano was supported by the Postdoctoral Fellowship from the Basque Government under Grant POS-2019-2-0017. The authors would like to thank "Nanotechnology in translational hyperthermia" (HIPERNANO)-RED2018-102626-T. We thank the ALBA (CLAESS beamline) synchrotron radiation facilities and staff for the allocation of beamtime and assistance during the experiments

Elucidating the role of shape anisotropy infaceted magnetic nanoparticles using biogenicmagnetosomes as a model

Shape anisotropy is of primary importance to understand the magnetic behavior of nanoparticles, but a rigorous analysis in polyhedral morphologies is missing. In this work, a model based on finite element techniques has been developed to calculate the shape anisotropy energy landscape for cubic, octahedral, and truncated-octahedral morphologies. In all cases, a cubic shape anisotropy is found that evolves to quasi-uniaxial anisotropy when the nanoparticle is elongated >= 2%. This model is tested on magnetosomes, similar to 45 nm truncated octahedral magnetite nanoparticles forming a chain inside Magnetospirillum gryphiswaldense MSR-1 bacteria. This chain presents a slightly bent helical configuration due to a 20 degrees tilting of the magnetic moment of each magnetosome out of chain axis. Electron cryotomography images reveal that these magnetosomes are not ideal truncated-octahedrons but present approximate to 7.5% extrusion of one of the {001} square faces and approximate to 10% extrusion of an adjacent {111} hexagonal face. Our model shows that this deformation gives rise to a quasi-uniaxial shape anisotropy, a result of the combination of a uniaxial (Ksh-u = 7 kJm(-3)) and a cubic (Ksh-c = 1.5 kJ m(-3)) contribution, which is responsible for the 20 degrees tilting of the magnetic moment. Finally, our results have allowed us to accurately reproduce, within the framework of the Landau-Lifshitz-Gilbert model, the experimental AC loops measured for these magnetotactic bacteria.Spanish Government is acknowledged for funding under the project number MAT2017-83631-C3. Basque Government is acknowledged for funding under the project number IT124519. HRTEM images were obtained in the Laboratorio de Microscopias Avanzadas at Instituto de Nanociencia de Aragon -Universidad de Zaragoza (LMA-INA). Authors acknowledge the LMA-INA for offering access to their instruments and expertise. Authors thank Prof. J. A. Garcia and I. Rodrigo for providing AC hysteresis loops

Nanoflowers Versus Magnetosomes: Comparison Between Two Promising Candidates for Magnetic Hyperthermia Therapy

Magnetic Fluid Hyperthermia mediated by iron oxide nanoparticles is one of the most promising therapies for cancer treatment. Among the different candidates, magnetite and maghemite nanoparticles have revealed to be some of the most promising candidates due to both their performance and their biocompatibility. Nonetheless, up to date, the literature comparing the heating ef ciency of magnetite and maghemite nanoparticles of similar size is scarce. To ll this gap, here we provide a comparison between commercial Synomag Nano owers (pure maghemite) and bacterial magnetosomes (pure magnetite) synthesized by the magnetotactic bacterium Magnetospirillum gryphiswaldense of hDi 40 45 nm. Both types of nanoparticles exhibit a high degree of crystallinity and an excellent degree of chemical purity and stability. The structural and magnetic properties in both nanoparticle ensembles have been studied by means of X Ray Diffraction, Transmission Electron Microscopy, X Ray Absorption Spectroscopy, and SQUID magnetometry. The heating ef ciency has been analyzed in both systems using AC magnetometry at several eld amplitudes (0 88 mT) and frequencies (130, 300, and 530 kHz).This work was supported in part by the Spanish "Ministerio de Ciencia, Investigación y Universidades'' under Project MAT2017-83631-C3-R, and in part by the Nanotechnology in Translational Hyperthermia (HIPERNANO) under Grant RED2018-102626-T. The work of Elizabeth M. Jefremovas was supported by the Beca Concepción Arenal through the Gobierno de Cantabria-Universidad de Cantabria under Grant BDNS: 406333. The work of Irati Rodrigo was supported by the Programa de Perfeccionamiento de Personal Investigador Doctor (Gobierno Vasco) under Grant POS-2020-1-0028 and Grant IT-1005-16. The work of Lourdes Marcano was supported by the Postdoctoral Fellowship from the Basque Government under Grant POS-2019-2-0017

Tuning the Magnetic Response of Magnetospirillum magneticum by Changing the Culture Medium: A Straightforward Approach to Improve Their Hyperthermia Efficiency

Magnetotactic bacteria Magnetospirillum magneticum AMB-1 have been cultured using three different media: magnetic spirillum growth medium with Wolfe’s mineral solution (MSGM + W), magnetic spirillum growth medium without Wolfe’s mineral solution (MSGM – W), and flask standard medium (FSM). The influence of the culture medium on the structural, morphological, and magnetic characteristics of the magnetosome chains biosynthesized by these bacteria has been investigated by using transmission electron microscopy, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism. All bacteria exhibit similar average size for magnetosomes, 40–45 nm, but FSM bacteria present slightly longer subchains. In MSGM + W bacteria, Co2+ ions present in the medium substitute Fe2+ ions in octahedral positions with a total Co doping around 4–5%. In addition, the magnetic response of these bacteria has been thoroughly studied as functions of both the temperature and the applied magnetic field. While MSGM – W and FSM bacteria exhibit similar magnetic behavior, in the case of MSGM + W, the incorporation of the Co ions affects the magnetic response, in particular suppressing the Verwey (∼105 K) and low temperature (∼40 K) transitions and increasing the coercivity and remanence. Moreover, simulations based on a Stoner–Wolhfarth model have allowed us to reproduce the experimentally obtained magnetization versus magnetic field loops, revealing clear changes in different anisotropy contributions for these bacteria depending on the employed culture medium. Finally, we have related how these magnetic changes affect their heating efficiency by using AC magnetometric measurements. The obtained AC hysteresis loops, measured with an AC magnetic field amplitude of up to 90 mT and a frequency, f, of 149 kHz, reveal the influence of the culture medium on the heating properties of these bacteria: below 35 mT, MSGM – W bacteria are the best heating mediators, but above 60 mT, FSM and MSGM + W bacteria give the best heating results, reaching a maximum heating efficiency or specific absorption rate (SAR) of SAR/f ≈ 12 W g–1 kHz–1.This work was supported by the Spanish MICINN/AEI/10.13039/501100011033 under Projects MAT2017-83631-C3-R and PID2020-115704RB-C3, the Basque Government under projects IT-1479-22 and IT-1500-22, and the BBVA Foundation under the Leonardo Fellowships for Researchers and Cultural Creators 2022. We thank the Helmholtz-Zentrum Berlin für Materialien und Energie for the allocation of synchrotron radiation beamtime and the support of the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. We thank the “Nanotechnology in translational hyperthermia” Network (RED2018-102626-T) funded by MCIN/AEI/10.13039/501100011033. Finally, we also thank A. Tato for her help in TEM and hysteresis loops measurements, R. Andrade and J.C. Raposo for technical and human support provided by SGIker (UPV/EHU/FEDER, EU), and A. García Prieto for her helpful comments and continuous support

Process design, kinetics, and techno-economic assessment of an integrated liquid phase furfural hydrogenation process

The integrated liquid phase process for producing furfuryl alcohol involves three stages: i) liquid–liquid extraction for recovering furfural from the aqueous solution obtained after a conventional steam-stripping hydrolysis reactor, ii) the hydrogenation reaction, and iii) the final purification. The reaction kinetics employed in the modelling are obtained experimentally. 2-methyltetrahydrofuran is the selected green solvent, and it has a high partition coefficient and stability under hydrogenating conditions. A commercial CuZnAl catalyst is used for the first time in the liquid phase furfural hydrogenation reaction, recording very high furfuryl alcohol selectivity even at complete conversion. A dual-site Langmuir-Hinshelwood model is developed and validated. An original aspect of this model is the kinetic effect of the low water content (0–5 wt%) remaining in the solvent after extraction. Water reduces the reaction rate by competing for active sites with furfural and furfuryl alcohol, without promoting other side-reactions. The optimization of the process leads to very high yields of furfuryl alcohol (97%) and a net production of 2-methyltetrahydrofuran even after recirculation and solvent losses. The process shows preliminary economic viability, with a minimum selling price for furfuryl alcohol of around 1,300 $/t; a competitive value only 30% higher than the furfural price considered in the analysis. Moreover, in contrast to current industrial processes that use copper chromite catalysts, the one developed here has environmental benefits, as it avoids the prior need for energy-intensive furfural-water distillation, eliminates toxic catalyst waste, and co-generates a green solvent.This work was supported by the University of the Basque Country (UPV/EHU), the European Union, through the European Regional Development Fund, the Spanish National Research Agency - Agencia Estatal de Investigación: PID-2021-122736OB-C43), and the Basque Government (Project IT1554-22)