ME - Artigos em revistas internacionais
Permanent URI for this collection
Browse
Browsing ME - Artigos em revistas internacionais by Field of Science and Technology (FOS) "Engenharia e Tecnologia::Engenharia Química"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Exploring Marine Biomineralization on the Al-Mg Alloy as a Natural Process for In Situ LDH Growth to Improve Corrosion ResistancePublication . Marques, Maria João; Mercier, Dimitri; Seyeux, Antoine; Zanna, Sandrine; Tenailleau, Christophe; Duployer, Benjamin; Jeannin, Marc; Marcus, Philippe; Basséguy; BASSEGUY, RegineABSTRACT: This study provides a detailed characterization of the AA5083 aluminum alloy, surface, and interface over 6 months of immersion in seawater, employing techniques such as SEM/EDX, GIXRD, mu-Raman and XPS. The purpose was to evaluate the evolution of the biomineralization process that occurs on the Al-Mg alloy. By investigating the specific conditions that favor the in situ growth of layered double hydroxide (LDH) during seawater immersion as a result of biomineralization, this research provides insights into marine biomineralization, highlighting its potential as an innovative and sustainable strategy for corrosion protection.
- New Modified SPEEK-Based Proton Exchange MembranesPublication . Teixeira, Fatima; Teixeira, António Paulo Silva; Rangel, Carmen M.ABSTRACT: A decarbonized society demands cleaner and sustainable energy sources based on well-established or emerging technologies with the potential to make a significant contribution to energy storage and conversion, such as batteries, fuel cells and water and/or CO2 electrolyzers. The performance of these electrochemical devices relies on key components such as their separators/ion-exchange membranes. The most common commercial membrane, Nafion (R), has several technological limitations. In this study, it is proposed the incorporation of bisphosphonic acid (BP) dopants into membrane matrices to improve their properties. Following this strategy, we prepared new membranes based on sulfonated poly(etheretherketone) (SPEEK) polymer, a reliable and effective alternative membrane polymer, through the incorporation of the BP dopants, to obtain low-cost membranes with improved properties. These membranes were structural, thermal and morphological, characterized by AT-FTIR, TGA and SEM. Their proton conductivity was evaluated over a temperature range between 30 degrees C and 60 degrees C, using Electrochemical Impedance Spectroscopy, and their stability during this process was also observed. The best proton conductivity was observed for the SPEEK membrane doped with BP1 at 2.0 wt% load at 60 degrees C, with a proton conduction of 226 mS cm-1.
- New proton exchange membranes based on ionic liquid doped chitosanPublication . Naffati, Naima; Teixeira, Fatima; Teixeira, António Paulo Silva; Rangel, Carmen M.ABSTRACT: The development of new proton exchange membranes (PEM) for electrochemical devices have attracted researcher's attention in the pursuit for more sustainable and cost-effective technologies for clean energy production and conversion. In this work, new doped chitosan (CS) membranes were prepared by the casting method. Chitosan is an abundant, biodegradable and non-toxic material, and as a membrane, a sustainable and cheaper alternative to those perfluorinated and commonly used, such as Nafion. Three different ionic liquids were employed as dopants, ([EMIM][OTf], [EMIM][FSI] and [MIMH][HSO4]), in various concentrations and up to 50 wt% load. The new membranes were characterized by ATR-FTIR, thermogravimetry, using TGA and DSC techniques to assess their thermal properties, and by SEM, to analyse their surface morphology. Proton conduction properties of the new membranes were assessed by Electrochemical Impedance Spectroscopy (EIS). The new doped membranes showed an increase in the proton conduction compared with pristine chitosan membranes. The incorporation of ionic liquids into chitosan membranes improved their proton conductivity and thermal properties, with [EMIM][OTf] and [MIMH][HSO4] showing the most promising results. A 2-fold increment in the proton conduction was generally observed with the increase of the temperature from 30 to 60 degrees C. The best proton conductivity was found at 60 degrees C for the membrane doped with [EMIM][OTf], with a value of 47 mS.cm(-1).
- Tetrahedrite Nanocomposites for High Performance ThermoelectricsPublication . Coelho, Rodrigo; Moço, Duarte; Sá, Ana; Luz, Paulo P. da; Neves, Filipe; Cerqueira, Maria de Fátima; Lopes, E.B.; Brito, Francisco; Mangelis, Panagiotis; Kyratsi, Theodora; Pereira Gonçalves, AntonioABSTRACT: Thermoelectric (TE) materials offer a promising solution to reduce green gas emissions, decrease energy consumption, and improve energy management due to their ability to directly convert heat into electricity and vice versa. Despite their potential, integrating new TE materials into bulk TE devices remains a challenge. To change this paradigm, the preparation of highly efficient tetrahedrite nanocomposites is proposed. Tetrahedrites were first prepared by solid state reaction, followed by the addition of MoS2 nanoparticles (NPs) and hot-pressing at 848 K with 56 MPa for a duration of 90 min to obtain nanocomposites. The materials were characterized by XRD, SEM-EDS, and Raman spectroscopy to evaluate the composites' matrix and NP distribution. To complement the results, lattice thermal conductivity and the weighted mobility were evaluated. The NPs' addition to the tetrahedrites resulted in an increase of 36% of the maximum figure of merit (zT) comparatively with the base material. This increase is explained by the reduction of the material's lattice thermal conductivity while maintaining its mobility. Such results highlight the potential of nanocomposites to contribute to the development of a new generation of TE devices based on more affordable and efficient materials.