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Recovery of Nd3+ and Dy3+ from E-Waste Using Adsorbents from Spent Tyre Rubbers
Publication . Nogueira, Miguel; Matos, Inês; Bernardo, Maria; Pinto, Filomena; Fonseca, Isabel; Lapa, Nuno; LAQV@REQUIMTE; Faculdade de Ciências e Tecnologia (FCT); MDPI - Multidisciplinary Digital Publishing Institute
This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO2 activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. The study also examines the efficiency of leaching rare earth elements from NdFeB magnets using optimised acid leaching methods, providing insights into recovery processes. The adsorption capacity of the materials was assessed through batch adsorption assays targeting neodymium (Nd3⁺) and dysprosium (Dy3⁺) ions. Results highlight the superior performance of activated carbon derived from tyre rubber following CO2 activation, with the best-performing adsorbent achieving maximum uptake capacities of 24.7 mg·g⁻1 for Nd3⁺ and 34.4 mg·g⁻1 for Dy3⁺. Column studies revealed efficient adsorption of Nd3⁺ and Dy3⁺ from synthetic and real magnet leachates with a maximum uptake capacity of 1.36 mg·g⁻1 for Nd3⁺ in real leachates and breakthrough times of 25 min. Bi-component assays showed no adverse effects when both ions were present, supporting their potential for simultaneous recovery. Furthermore, the adsorbents effectively recovered rare earth elements from e-waste magnet leachates, demonstrating practical applicability. This research underscores the potential of tyre rubber-derived adsorbents to enhance sustainability in critical raw material supply chains. By repurposing waste tyre rubber, these materials offer a sustainable solution for rare earth recovery, addressing resource scarcity while aligning with circular economy principles by diverting waste from landfills and creating value-added products.
Effect of Bark Biochars on Properties of Steam-Activated Carbons
Publication . Şen, Umut; Nobre, Catarina; Martins, Marta; Gonçalves, Margarida; Pereira, Helena; DQ - Departamento de Química; MEtRICS - Centro de Engenharia Mecânica e Sustentabilidade de Recursos; MDPI AG
Bark is a heterogeneous solid material comprising mainly of phloem and cork fractions. These fractions differ in chemical composition and anatomical structure, and value-added activated carbons produced from these fractions have different surface properties. Low-temperature pyrolysis was shown to be a promising method for producing activated carbon precursors from bark fractions at higher yields than conventional slow pyrolysis. Here, we produced mesoporous activated carbons (ACs) from cork and phloem fractions of Quercus cerris bark by low-temperature pyrolysis followed by steam activation at 900 °C. The results showed steam-activation of biochars from Q. cerris bark fractions yielded ACs with acceptable surface properties. The ACs contained 9.9% and 23.3% ash content, and specific surface areas of 201 m2 g−1 and 512 m2 g−1 for cork and phloem fractions, respectively. Calcium was the principal inorganic component of ACs, followed by potassium, silicon, and iron. Surface functional groups of bark fractions and biochars were lost during steam activation, as evidenced by FT-IR spectroscopy. The burnout temperatures of cork and phloem ACs were 726 °C and 736 °C, respectively. The ACs showed a high methylene blue and methyl orange adsorption capacity, with the removal of 80% and 90% of methylene blue and 58% and 68% of methyl orange after 48 h for cork and phloem ACs, respectively.
Removal of Paracetamol and Cu2+ from Water by Using Porous Carbons Derived from Agrowastes
Publication . Ferreira, Regiane C.; de Araújo, Thiago Peixoto; Dias, Diogo; Bernardo, Maria; Lapa, Nuno; Fonseca, Isabel M.; de Barros, Maria A. S. D.; DQ - Departamento de Química; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Dende and babassu coconuts are largely used in tropical countries, namely in Brazil, for the extraction of oils from kernels. The remaining biowastes are industrially processed to produce porous carbons (PCs). PCs derived from dende and babassu biowastes and produced at an industrial scale have been characterized by textural, chemical, and ecotoxicological parameters. A commercial activated carbon (CC) of mineral origin has been used as a benchmarking material. Although the CC sample presented a higher surface area (SBET = 1083 m2/g), the PCs derived from the biowastes were richer in micropores (Vmicro = 0.25–0.26 cm3/g), while the CC carbon presented wider pore size distribution with a higher mesopore volume (Vmeso = 0.41 cm3/g). All the adsorbents used in this work have shown a non-acute ecotoxic behavior for the bacterium Vibrio fischeri (EC50-30 min > 99% v/v). The adsorbents have been tested for paracetamol and Cu2+ adsorption in mono- and bicomponent solutions. The uptake capacities of paracetamol (qe, 98–123 mg g−1) and Cu2+ (qe, 15–18 mg g−1) from monocomponent solutions were similar to the ones obtained in the bicomponent solutions, indicating no competition or cooperative effects but a site-specific adsorption. This finding represents an advantage for the removal of these adsorbates when present in the same solution as they can be adsorbed under similar rates as in the single systems. Paracetamol adsorption was related to micropore filling, π-π interactions, and H-bonding, whereas Cu2+ removal was attributed to the cation exchange mechanism and complexation to the hydroxyl groups at the carbons’ surface.
Prediction of Carbon Dioxide and Methane Adsorption on UiO-66 Metal–Organic Framework via Molecular Simulation
Publication . Maia, João M. M.; Ribeiro, Rui P. P. L.; Mota, José P. B.; DQ - Departamento de Química; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
The adsorption equilibrium of methane (CH4) and carbon dioxide (CO2) on the metal–organic framework (MOF) UiO-66 is studied via molecular simulation. UiO-66 is a versatile MOF with vast potential for various adsorption processes, such as biogas upgrading, CO2 capture, and natural gas storage. The molecular simulations employ the grand canonical Monte Carlo (GCMC) method, covering a temperature range of 298–343 K and pressures up to 70 bar for CH4 and 30 bar for CO2. The accuracy of different forcefields in describing the adsorption equilibria is evaluated. Two modelling approaches are explored: (i) lumping each hydrogen atom in the MOF framework to the heavy atom it is bonded to (united atom approximation) and (ii) considering explicit hydrogen atoms. Additionally, the influence of electrical charges on CO2 adsorption is also evaluated. The findings indicate that the most effective forcefield to describe the adsorption equilibrium is a united atom forcefield based on the TraPPE parametrization. This approach also yields an accurate calculation of the isosteric heat of adsorption. In the case of CO2, it is observed that the use of electrical charges enhances the prediction of the heat of adsorption, especially in the low-coverage region.
Horizontal migration of zooplankton in lake–wetland interfaces. Can temperature-driven surface exchange flows modulate its patterns?
Publication . Pereira, Joana Luísa; Lopes, Ana Sofia; Silva, Júlia; Vidal, Tânia; Abrantes, Nelson; Santos, Daniela; Brito, Moisés; Ferreira, Rui M. L.; Gonçalves, Fernando J. M.; Ricardo, Ana Margarida; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; Springer Science and Business Media Deutschland GmbH
Lake ecology can be affected by exchange flows driven by horizontal temperature gradients in lake–wetland interfaces. In this work, we investigate the hypothesis that thermally driven flows modulate the horizontal migration patterns of freshwater zooplankters. A 48-h field campaign in a shallow lake (Lake Vela, Quiaios, Portugal) was carried out to test this hypothesis. Thermal differences between the littoral and limnetic areas were measured along two transects featuring a Schoenoplectus lacustris and a Myriophyllum aquaticum stand in the littoral. In parallel, the physiochemistry and chlorophyll a, as a proxy for food availability differences between the littoral and the limnetic zones, were monitored. Zooplankton samples were collected for assessing overall and group-specific number-density differences. The diel period (day or night) and the site (littoral or limnetic zone) did not interact significantly to modulate the variation patterns for the studied physiochemical variables, indicating that these parameters should not explain horizontal zooplankton distribution patterns. The expected patterns for zooplankton diel horizontal migration as driven by the presence of visual predators were occasionally confirmed by our limnetic versus littoral abundance records through time, depending on the transect. Group-specific abundance patterns indicate particular features: copepods always preferred the littoral over the limnetic zone regardless of the diel period; chydorids always preferred the littoral zone regardless of the macrophyte stand involved; bosminids tended to preferentially concentrate in the limnetic zone. No consistent relationship was identified between the expected flow direction due to temperature differences and zooplankton abundance changes, although it occasionally occurred through the dataset.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
DL 57/2016
Número da atribuição
DL 57/2016/CP1482/CT0134