Artigos de Revista

Info Electrodialytic removal of tungsten and arsenic from secondary mine resources Deep eutectic solvents enhancement

Tungsten is a critical raw material for European and U.S. economies. Tungsten mine residues, usually considered an environmental burden due to e.g. arsenic content, are also secondary tungsten resources. The electrodialytic (ED) process and deep eutectic solvents (DES) have been successfully and independently applied for the extraction of metals from different complex environmental matrices. In this study a proof of concept demonstrates that coupling DES in a two-compartment ED set-up enhances the removal and separation of arsenic and tungsten from Panasqueira mine secondary resources. Choline chloride with malonic acid (1:2), and choline chloride with oxalic acid (1:1) were the DES that in batch extracted the average maximum contents of arsenic (16%) and tungsten (9%) from the residues. However, when ED was operated at a current intensity of 100 mA for 4 days, the extraction yields increased 22% for arsenic and 11% for tungsten, comparing to the tests with no current. From the total arsenic and tungsten extracted, 82% and 77% respectively were successfully removed from the matrix compartment, as they electromigrated to the anolyte compartment, from where these elements can be further separated. This achievement potentiates circular economy, as the final treated residue could be incorporated in construction materials production, mitigating current environmental problems in both mining and construction sectors.

Ano: 2020

Autor(es): Almeida, J.; Craveiro, R.; Faria, P.; Santos Silva, A.; Mateus, E.; Barreiros, S.; Paiva, A.; Ribeiro, A.

Revista: Science of The Total Environment

Editor: Elsevier

Volume: Volume 710.

DOI: https://doi.org/10.1016/j.scitotenv.2019.136364

Keywords: Choline chloride/oxalic acid; Choline chloride/malonic acid; Electro-based technology; Secondary resource; Harmful compound; Critical raw material

Info Enhancing estuarine flood risk management: comparative analysis of three estuarine systems

Estuarine flood risk management is a challenge for coastal managers since this type of system is usually complex due to the presence of multiple trigger combinations that can induce flood events affecting different types of human occupation. Furthermore, legal directives demanded countries to have flood risk assessment tools therefore enhancing knowledge on estuarine triggers and flood damage typologies is useful for coastal managers. In this study three different flood events are compared and contrasted, each one having occurred in a different estuarine system chosen based on a set of criteria (temporal proximity, occurrence of human damages and at least three flood triggers identified in each database). The diversity of data sources that characterizes each database was examined, for the three events, which are described in terms of triggers and damages. The comparison highlighted that the local context was important in the estuarine flood combination of triggers and disclosed two categories (one category comprising infrastructure economic and human damages; and another category involving circulation interruption and functions disruption) of flood damages common between the studied systems corresponding to different levels of relevance for management. The enhanced knowledge acquired allowed the construction of a conceptual framework for damages that can contribute to more adequate estuarine flood risk frameworks.

Ano: 2020

Número Páginas: 935-939pp.

Autor(es): Rilo, Ana; Tavares, A.; Freire, P.; Zêzere, J. L.; Haigh, I.

Revista: Journal of Coastal Research

Editor: Coastal Education and Research Foundation (CERF)

Volume: SI 95.

DOI: https://meridian.allenpress.com/jcr/issue/95/SI

Keywords: flood risk management; triggers; damages; Estuaries

Info Exploring teenagers' spatial practices and needs in light of new communication technologies

Info Flooding occurrences in the portuguese continental coastal zone: a database for the period 1980-2018

The Portuguese continental coastal zone is characterized by its lithological, morphological, biological and landscape diversity. With a coastline extension of approximately 987 km, this zone has great importance in the national context. The increasing anthropic occupation of the coastal zone in the last seven decades led to a conflict with the natural dynamics of these areas. The project MOSAIC.pt emerges from the need of a comprehensive flood risk management framework for the Portuguese coastal zones, including estuaries. One of the innovative challenges of this project is to identify the coastal critical typologies affected by flooding, based in historical data. Hence, a historical database of coastal flood occurrences was created for the period 1980-2018. Historical data was collected in national and regional newspapers. The database includes relevant information such as flood triggering factors and impacts. For the period 1980-2018, a total of 398 occurrences of coastal overtopping and flooding were identified. The analysis shows that the vast majority of occurrences are located on the Portuguese western coast. In terms of impacts, the typologies associated with material, natural, environmental and lastly human impacts stand out. Results provide relevant temporal and spatial information about coastal historical flood occurrences and contribute for the design of a risk framework.

Ano: 2020

Número Páginas: 7p.

Autor(es): Barros, J.; Freire, P.; Perdiz, L.; Tavares, A.

Revista: e-proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL2020 PSAM15), 01 06 November 2020 Venice, Italy. Edited

Editor: Research Publishing Services

DOI: https://www.rpsonline.com.sg/proceedings/esrel2020/html/4202.xml

Keywords: Occurrences; Impacts; Database; Flood; Coastal zone

Info Hybrid monitoring-modelling analysis on the storm induced sediment dynamics of a structure-controlled beach

Info Importance of infragravity waves in a wave-dominated inlet under storm conditions

The processes associated with infragravity waves (IGW) and their role on the hydro-sedimentary dynamics of a wave-dominated inlet are investigated using field observations collected at the Albufeira Lagoon (Portugal) during storm Leslie in October 2018. During the storm, significant IGW heights reached up to 1.0 m in the surf zone and 0.4 m inside the lagoon. IGW frequencies were blocked by ebb currents at the flood-delta and this effect was stronger for higher IGW frequencies. Therefore, low-frequency IGW were able to propagate further into the inner lagoon. The application of a 1D energy balance equation suggests that depth-induced breaking and bottom friction contributed equally to dissipate IGW energy at the flood-delta and that this dissipation was stronger during the flood than during the ebb. Large horizontal velocities under IGW crests increased the instantaneous suspended sediment transport rate by up to two orders of magnitude during flood at the flood-delta. The net suspended sediment transport rate and its variability, associated with the wave motion, was positive (landward) during flood and negligible during ebb. These positive values were associated with large wave-induced orbital velocities, suggesting that waves were more effective than tidal currents in inducing suspended sediment transport. The oscillatory suspended sediment transport rate was directed towards the lagoon and dominated by IGW frequencies. The observed sediment accretion of the northern channel occurred during the most energetic IGW. The measurements presented in this study and their analyses demonstrate how IGW play a major role in the sedimentary dynamics of wave-dominated inlets during storm conditions.

Ano: 2020

Número Páginas: 1-15pp.

Autor(es): Mendes, D.; Fortunato, A. B.; Bertin, X.; Martins, K.; Lavaud, L.; Silva, A. N.; Pires Silva, A.; Coulombier, T.; Pinto, J.

Revista: Continental Shelf Research

Editor: Elsevier

Volume: 192.

DOI: https://doi.org/10.1016/j.csr.2019.104026

Keywords: Waves; Infragravity

Info Influence of laboratory aggregate compaction method on the particle packing of stone mastic asphalt

The type of aggregates and their packing characteristics under compaction are key factors for the design of asphalt mixtures with improved performance, namely, with respect to resistance to permanent deformation. A good example is Stone Mastic Asphalt (SMA), known by its stoneonstone structure. In the U.S.A., the aggregate particles packing characteristics in a SMA, specially the stoneonstone effect, are normally assessed using the manually dryrodded method. However, this method may not be representative of field aggregate particle packing conditions, which may compromise the SMA performance. This article presents new findings regarding aggregate laboratory compaction methods to optimise the coarse aggregate structure in a SMA. Particle breakage, bulk density, air voids (compacted & uncompacted skeleton) in the aggregate / coarse aggregate were assessed for existing methods as well as for new methods using existing compactors, but with different procedures and/or specific devices, e.g. Proctor hammer. The assessed methods were: (1) noncompaction; (2) manually dryrodded method; (3) established Proctor compaction; (4) modified Proctor compaction (light and heavy compaction) and (5) steel roller compaction. The 2 latter new methods aimed at mechanically simulating the dry-rodded method and the effect of field compactors, respectively. The results highlight that the new laboratory compaction methods developed with Proctor and steel roller compactor, provide a particle packing that is more representative of the field conditions, comparatively to other aggregate compaction methods.

Ano: 2020

Número Páginas: 10.

Autor(es): Miranda, H.; Batista, F. A.; Antunes, M. L.; Neves, J.

Revista: Journal homepage: www.elsevier.com/locate/conbuildmat

Editor: Construction and Building Materials

Keywords: Stone mastic asphaltParticle packingStoneonstoneAggregate compaction methodsAir voids in coarse aggregate mixture

Info Influence of the aggregate skeleton matrix and volumetric composition on the resistance of stone mastic asphalt to permanent deformation

Info Macrobiological degradation of esterified wood with sorbitol and citric acid

There is a need for new solutions in wood protection against marine wood borers and termites in Europe. A new solution could be the esterification of wood with sorbitol and citric acid (SCA) since these are inexpensive and readily available feedstock chemicals and have shown protective properties against fungal wood degradation in earlier studies and prevented macrobiological degradation, as shown in this study. Protection of wood products in the marine environment lacks available wood preservatives that are approved for marine applications. Termite infestation is opposed mainly by biocide treatments of wood. Several wood modification systems show high resistance against both marine borers and subterranean termites. However, the existing commercialized wood modification products are costly. Both macrobiological forms of degradation represent a great threat for most European wood species, which are rapidly and severely degraded if not properly treated. This study investigated esterified wood in standard field trials against marine wood borers, and against subterranean termites in laboratory trials in a no-choice and choice test. The treatment showed good resistance against wood borers in the marine environment after one season and against subterranean termites in the laboratory after eight weeks. The low termite survival rate (SR) in the no-choice test during the first week of testing indicates a mode of action that is incomparable to other wood modification treatments.

Ano: 2020

Número Páginas: 11p.

Autor(es): Treu, A.; Lina Nunes; Larnoy, E.

Revista: Forests

Editor: MPDI

Volume: 11, 776.

DOI: https://doi.org/10.3390/f11070776

Keywords: Subterranean termites; Marine wood borers; Polyesterification; Wood protection

Info Mechanical performance of glulam products made with Portuguese poplar