Browsing by Issue Date, starting with "2022-04"
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- Structural and Optical Characterization of Mechanochemically Synthesized CuSbS2† [Abstract]Publication . Esperto, Luís; Figueira, Isabel; Mascarenhas, João; Silva, Teresa; Correia, J.B.; Neves, FilipeABSTRACT: The present work describes experimental studies related to the characterization of CuSbS2 directly synthesized after 2 h of mechanochemical synthesis (MCS) at 340 rpm, starting from mixtures of elemental powders. X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy were carried out to analyze the crystal structure, degree of crystallinity, crystallite size and optical properties of the mechanochemically synthesized CuSbS2 powders. Rietveld refinement was carried out using Diffrac. TOPAS (Bruker AXS). Thermal stability of the synthesized materials was evaluated by the vacuum thermal heat treatment of the mechanochemically synthesized CuSbS2 powders at 350 °C for 24 h. Furthermore, the CuSbS2 powders were also analyzed by field-emission scanning electron microscopy (FE-SEM), laser diffraction, and differential thermal analysis.
- Solid-gas reactors driven by concentrated solar energy with potential application to calcium looping: A comparative reviewPublication . Rivero, Mayra Alvarez; Rodrigues, Diogo; Pinheiro, Carla I.C.; Cardoso, João P.; Mendes, Luís FilipeABSTRACT: The calcium looping process, based on the reversible calcination-carbonation reaction cycle of CaCO3-CaO, is an emerging and promising technology for thermochemical energy storage in concentrating solar power plants. In this process, concentrated solar energy is used to carry out the endothermic solar-driven calcination of CaCO3 with formation of CaO and CO2 as products in a solid-gas reactor. In this review, a number of experimental studies of solid-gas reactors driven by concentrated solar energy are discussed, with a particular focus on solar reactors for calcination of CaCO3 or with that potential application. The solid-gas reactors for solar-driven calcination of CaCO3 reported in the literature achieved a total efficiency of 16.6%-88% for a mass flow rate up to 25 kg h(-1) and a power up to 55 kW. Also, a detailed comparison of the different types of solid-gas reactors driven by concentrated solar energy is provided by outlining their advantages and disadvantages according to several relevant criteria. This review is intended to be a valuable tool for the selection of a reactor configuration for future studies related to solar-driven calcination of CaCO3.
- Lithium metallurgical processing from primary resources [Comunicação oral]Publication . Nogueira, Carlos
- From Wind to Hybrid: A Contribution to the Optimal Design of Utility-Scale Hybrid Power PlantsPublication . Silva, Ana Rita; Estanqueiro, AnaABSTRACT: When a substantial number of wind parks are approaching the end of their lifespan, and developers of renewables are facing decisions about what to do with their assets, concepts such as hybrid power plants are emerging as a promising solution to enable renewable integration in a cost-effective and robust manner. This work proposes a decision-aid algorithm to perform a comprehensive analysis of hybrid power plants, focusing on the energetic contribution and economic feasibility of converting existing wind power plants into hybrid power plants (i.e., installing photovoltaic panels and a storage system). The analysis was performed by comparing the option of converting existing wind plants into hybrid plants with a pure repowering exercise or overplanting using wind technology only. The obtained results unequivocally demonstrate the added value of hybrid power plants as they promote: (i) a higher installed capacity and yearly capacity factor (up to 50%); (ii) an increased efficiency of existing electric infrastructures; and (iii) a positive contribution to a sustainable energy system with the ability to generate economic value.
- Panorama de medidas de adaptação e mitigação às alterações climáticas em edifícios na EuropaPublication . Simoes, SofiaRESUMO: Foi recentemente publicado o AR6 WG II Report: 6º Relatório de Avaliação do Grupo de Trabalho II do Painel Inter-governamental para as Alterações Climáticas (IPCC) que foca Impactos, Adaptação e Vulnerabilidade. O relatório foi aprovado em 27 fevereiro por 195 governos membros do IPCC e apela à ação urgente, necessária para lidar com os riscos crescentes. A principal mensagem é que as alterações climáticas são uma ameaça ao bem-estar humano e à saúde do planeta e que a ação atempada (mas urgente) pode garantir o nosso futuro comum.
- GeoERA Raw Materials Monograph : the past and the futurePublication . Wittenberg, Antje; de Oliveira, Daniel Pipa Soares; Flindt Jørgensen, Lisbeth; González, Javier; Heldal, Tom; Aasly, Kari Aslaksen; Deady, Eimear; Kumelj, Špela; Horvath, Zoltan; McGrath, Eoin; Ferreira, Maria João; Calabaça, Teresa; Arvanitidis, Nikolaos; Sadeghi, Martiya; Bertrand, Guillaume; Gloaguen, Eric; Decree, Sophie; Gautneb, Håvard; Törmänen, Tuomo; Reginiussen, Helge; Sievers, Henrike; Quental, Lídia; Pereira, Aurete; Medialdea, Teresa; Schiellerup, Henrik; Zananiri, Irene; Ferreira, Pedro Tavares; Somoza, Luis; Monteys, Xavier; Alcorn, Trevor; Marino, Egidio; Lobato, Ana Belén; Kuhn, Thomas; Nyberg, Johan; Malyuk, Boris; Magalhães, Vítor Hugo; Lunar, Rosario; Hein, J. R.; Cherkashov, Georgy; Brown, Teresa; Cassard, Daniel; Urvois, Marc; Pedersen, Mikael; Schjøth, Frands; Tulstrup, Jørgen; Eilu, Pasi; Hokka, Janne; Simoni, Mark; Carvalho, Jorge; Laskaridis, Kostas; Dedić, Željko; Habimana, Cyprien; Liinamaa-Dehls, AnneABSTRACT: GeoERA Minerals projects have produced data aimed at supporting Europe’s minerals sector and to assist the European Commission to realise its goals for raw materials. Data has been compiled on mineral occurrences and mineral provinces across Europe, in particular, areas with potential to host Critical Raw Materials. Anecdotal evidence from the minerals sector provides an indication of the likelihood of exploration leading to mine development. For every 1,000 mineral showings examined, only 100 may receive further exploration work and of those 100, only 10 may warrant more detailed sampling either through trenching, drilling or other means and of those 10 only 1 may proceed to an evaluation through a full feasibility study which itself has only 50% chance of being positive. Following this, any project for which a mine proposal is made must undergo a full evaluation and permitting by authorities including full public consultation. The proposal may or may not pass this scrutiny. In terms of a schedule, the generally accepted minimum time frame from discovery to production is 10 years and usually much more, up to 20 years.
- Hydrometallurgical recovery of platinum-group metals from spent auto-catalysts: Focus on leaching and solvent extractionPublication . Paiva, A. P.; Piedras, Francisco Vega; Rodrigues, Pedro G.; Nogueira, CarlosABSTRACT: To ensure the supply of raw materials for products of extreme importance in strategic sectors, the recovery of critical metals from secondary sources becomes increasingly urgent. Platinum group metals (PGMs), being rare and very valuable, fall into this demand, and the catalytic converters that contain them are recognized as one of the main sources. Hydrometallurgical processes have been proposed as an alternative to pyrometallurgical ones, with leaching and separation by solvent extraction being core operations in this type of processing. This article investigates these two operations, seeking to optimize conditions and propose new arrangements to improve them. Two different catalyst samples were considered in the experimental work. Leaching was carried out involving concentrated HCl solutions (with H2O2 as oxidant) and low liquid/solid ratios, seeking to maximize PGMs recovery, guaranteeing their high concentration in leachates and minimizing aluminum co-dissolution. Cerium leaching was also followed since this is a rare-earth metal with potential interest. Temperature, HCl concentration, liquid/solid ratio (L/S), time and particle size factors were evaluated, and the optimized conditions found were 11.6 mol L-1 HCl, 1%vol H2O2, 60 C, L/S = 2 L kg(-1) and 3 h, leading to PGM yields of 90-98% Pt, 99% Pd and 70-96% Rh, and leachate compositions of 0.41-0.78 g L-1 Pt, 1.6 g L-1 Pd, 0.062-0.066 g L-1 Rh, depending on the catalyst sample.& nbsp;For solvent extraction (SX), several commercial extractants dissolved/diluted in toluene were checked, firstly with a model solution, and then applied to the real spent auto-catalyst (SAC) leachates produced in-situ. The overall results showed that the most promising SX systems among those tested were Cyanex (R) 471X and Cyphos (R) IL 101. Cyanex (R) 471X allowed the quantitative extraction of Pd(II) and Fe(III), but the latter was conveniently scrubbed by water prior to Pd(II) stripping by an acidic thiourea solution. Pt(IV) and Pd(II) extraction values by Cyphos (R) IL 101 were very encouraging, as only Fe(III) and Zn(II) were appreciably co-extracted, however, scrubbing of the contaminating metals, and Pd(II) and Pt(IV) stripping, did not work. Hence, investigation to find proper scrubbing/stripping agents for Cyphos (R) IL 101 SX system, to recover PGMs from recycled SACs, is further needed.
- Protocolos de microalgas de la Red RENUWALPublication . Navarro Llorens, Juana María; Gouveia, LuisaRESUMEN: Las microalgas pueden ser utilizadas para la recuperación de nutrientes contenidos en diversos efluentes, contribuyendo de esta forma a la mejora de la sostenibilidad de multitud de procesos. Sin embargo, para poder conseguir procesos eficientes es necesario evaluar con detalle cada aplicación en función de los efluentes que se van a procesar. Dependiendo del proceso, la biomasa algal obtenida puede tener interés para su aplicación en distintos sectores y productos finales con diferente valor añadido, i.e., farmacéutico, cosmético, agroalimentario-ganadero-acuícola, ambiental, químico o incluso energético. En el año 2019, varios grupos de investigación pertenecientes a diferentes países iberoamericanos junto con 6 empresas que trabajan con microalgas se unieron para solicitar al programa de Redes de la CYTED (Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo; https://www.cyted.org/es/cyted) la creación de una red temática para el tratamiento de efluentes con microalgas. Las Redes Temáticas que subvenciona este organismo, son asociaciones de grupos de investigación y desarrollo (I+D) de entidades públicas o privadas y empresas de los países miembros del Programa CYTED, cuyas actividades científicas o tecnológicas están relacionadas dentro de un ámbito común de interés y enmarcadas en una de las Áreas del Programa. En nuestro caso, la red se solicitó por el área industrial. La red RENUWAL 320RT0005 fue concedida en esta convocatoria del 2019 para iniciarse en el año 2020 durante un periodo de 4 años que, con motivo de la Pandemia, se ha extendido hasta el 2024 (https://www.cyted.org/es/renuwal).
- Voa alto com o Copernicus para observar a Terra [Comunicação oral]Publication . Quental, Lídia
- Impact of high-pressure homogenization on the cell integrity of Tetradesmus obliquus and seed germinationPublication . Ferreira, Alice; Figueiredo, Daniel; Ferreira, Francisca; Ribeiro, Belina; Reis, Alberto; Lopes da Silva, Teresa; Gouveia, LuisaABSTRACT: Microalgae have almost unlimited applications due to their versatility and robustness to grow in different environmental conditions, their biodiversity and variety of valuable bioactive compounds. Wastewater can be used as a low-cost and readily available medium for microalgae, while the latter removes the pollutants to produce clean water. Nevertheless, since the most valuable metabolites are mainly located inside the microalga cell, their release implies rupturing the cell wall. In this study, Tetradesmus obliquus grown in 5% piggery effluent was disrupted using high-pressure homogenization (HPH). Effects of HPH pressure (100, 300, and 600 bar) and cycles (1, 2 and 3) were tested on the membrane integrity and evaluated using flow cytometry and microscopy. In addition, wheat seed germination trials were carried out using the biomass at different conditions. Increased HPH pressure or number of cycles led to more cell disruption (75% at 600 bar and 3 cycles). However, the highest increase in wheat germination and growth (40-45%) was observed at the lowest pressure (100 bar), where only 46% of the microalga cells were permeabilised, but not disrupted. Non-treated T. obliquus cultures also revealed an enhancing effect on root and shoot length (up to 40%). The filtrate of the initial culture also promoted shoot development compared to water (21%), reinforcing the full use of all the process fractions. Thus, piggery wastewater can be used to produce microalgae biomass, and mild HPH conditions can promote cell permeabilization to release sufficient amounts of bioactive compounds with the ability to enhance plant germination and growth, converting an economic and environmental concern into environmentally sustainable applications.