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Your search keyword '"Rebelo, Luís Paulo N."' showing total 247 results
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247 results on '"Rebelo, Luís Paulo N."'

2. one-step extraction and separation of betalains and chlorophylls using thermoreversible aqueous biphasic systems

Author

Rosa, Marguerita E., Ferreira, Ana M., Neves, Catarina M. S. S., Almeida, Mafalda R., Barros, Rafael, Cristovão, Ana C., Sousa, Ana C. A., Reis, Patrícia M., Rebelo, Luís Paulo N., Esperança, José M. S. S., Coutinho, João A. P., Freire, Mara G., LAQV@REQUIMTE, and DQ - Departamento de Química

Subjects
Environmental Chemistry, SDG 8 - Decent Work and Economic Growth, SDG 12 - Responsible Consumption and Production, Pollution
Abstract

This work was partly developed within the scope of the projects CICECO-Aveiro Institute of Materials, LA/P/0006/2020 and the Associate Laboratory for Green Chemistry-LA/P/0008/2020, financed by national funds through the FCT/MCTES (PIDDAC). Publisher Copyright: © 2023 The Royal Society of Chemistry. Globally, up to 50% of root crops, fruits and vegetables produced is wasted. Beetroot stems and leaves fit into this scenario, with only a small fraction being used in cattle food. One way of approaching this problem is through their valorisation, by extracting and recovering valuable compounds present in this type of waste that could be used in other applications, while contributing towards a circular economy. In this work, a new integrated process using thermoreversible aqueous biphasic systems (ABS) composed of quaternary ammonium-based ionic liquids (ILs) and polypropyleneglycol 400 g mol−1 (PPG) is shown to allow the one-step extraction and separation of two pigment classes—betalains and chlorophylls—from red beet stems and leaves. The pigment extraction was carried out with a monophasic aqueous solution of the IL and PPG, whose phase separation was then achieved by a temperature switch, resulting in the simultaneous separation of chlorophylls and betalains into opposite phases. A central composite design was used to optimise the extraction parameters (time, temperature, and solid : liquid (S/L) ratio) of both pigment extraction yields, reaching at 20 °C, 70 min and a S/L ratio of 0.12 a maximum extraction yield of 6.67 wt% for betalains and 1.82 wt% for chlorophylls (per weight of biomass). Moreover, it is shown that aqueous solutions of ILs better stabilise betalains than the gold standard solvent used for the extraction method. Among the studied systems, the ABS comprising the IL N-ethyl-N-methyl-N,N-bis(2-hydroxyethyl) bromide ([N21(2OH)(2OH)]Br) presented the best separation performance, with an extraction efficiency of 92% and 95% for chlorophylls and betalains, respectively, for opposite phases. The pigments were removed from the respective phases using affinity resins, with high recoveries: 96% for betalains and 98% for chlorophylls, further allowing the IL reuse. Finally, the cyto- and ecotoxicities of the quaternary ammonium-based ILs were determined. The obtained results disclosed low to negligible toxicity in the thousands of mg L−1 range, with [N21(2OH)(2OH)]Br being harmless from an ecotoxicological point of view. Overall, it is shown here that the developed process is an innovative approach for the one-step extraction and selective separation of pigments contributing to the valorisation of waste biomass. publishersversion published

Published
2023

3. Valorisation of red beet waste: one-step extraction and separation of betalains and chlorophylls using thermoreversible aqueous biphasic systems

Author

Rosa, Marguerita E., primary, Ferreira, Ana M., additional, Neves, Catarina M. S. S., additional, Almeida, Mafalda R., additional, Barros, Rafael, additional, Cristovão, Ana C., additional, Sousa, Ana C. A., additional, Reis, Patrícia M., additional, Rebelo, Luís Paulo N., additional, Esperança, José M. S. S., additional, Coutinho, João A. P., additional, and Freire, Mara G., additional

Published
2023
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14. Isotope Effects

Author

Wolfsberg, Max, primary, Hook, W. Alexander, additional, Paneth, Piotr, additional, and Rebelo, Luís Paulo N., additional

Published
2009
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16. Simultaneous Separation of Antioxidants and Carbohydrates From Food Wastes Using Aqueous Biphasic Systems Formed by Cholinium-Derived Ionic Liquids

Author

Neves, Catarina M. S. S., primary, Figueiredo, Marcos, additional, Reis, Patrícia M., additional, Sousa, Ana C. A., additional, Cristóvão, Ana C., additional, Fiadeiro, Mariana B., additional, Rebelo, Luís Paulo N., additional, Coutinho, João A. P., additional, Esperança, José M. S. S., additional, and Freire, Mara G., additional

Published
2019
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26. Mutual Solubility of Water and Structural/Positional Isomers of N-Alkylpyridinium-Based Ionic Liquids

Author

Freire, Mara G., Neves, Catarina M. S. S., Shimizu, Karina, Bernardes, Carlos E. S., Marrucho, Isabel M., Coutinho, João A. P., Lopes, José N. Canongia, and Rebelo, Luís Paulo N.

Abstract

Despite many previous important contributions to the characterization of the liquid−liquid phase behavior of ionic liquids (ILs) plus water systems, a gap still exists as far as the effect of isomers (of ILs) is concerned. Therefore, in this work, a comprehensive study of the liquid−liquid equilibria between water and isomeric pyridinium-based ionic liquids has been performed. Atmospheric pressure mutual solubilities between water and pyridinium-based ionic liquids combined with the common anion bis[(trifluoromethyl)sulfonyl]imide were experimentally determined between (288.15 and 318.15) K. The main goal of this work is to study the isomeric effects on the pyridinium-based cation, namely, the structural and positional isomerism, as well as the alkyl side chain length. To the best of our knowledge, the influence of both structural and positional isomerism on the liquid−liquid behavior in ionic-liquid-water-containing systems is an unexplored field and is here assessed for the first time. Moreover, from the experimental solubility data, several infinite dilution molar thermodynamic functions of solution, namely, the Gibbs energy, the enthalpy, and the entropy, were estimated and discussed. In addition, aiming at gathering a broader picture of the underlying thermodynamic solvation phenomenon, molecular dynamics simulations were also carried out for the same experimental systems.

Published
2024
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30. Antitumor Activity of Ionic Liquids Based on Ampicillin

Author

Ferraz, Ricardo, primary, Costa-Rodrigues, João, additional, Fernandes, Maria H., additional, Santos, Miguel M., additional, Marrucho, Isabel M., additional, Rebelo, Luís Paulo N., additional, Prudêncio, Cristina, additional, Noronha, João Paulo, additional, Petrovski, Željko, additional, and Branco, Luís C., additional

Published
2015
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39. Unveiling the dual role of the cholinium hexanoate ionic liquid as solvent and catalyst in suberin depolymerisation

Author

Ferreira, Rui, primary, Garcia, Helga, additional, Sousa, Andreia F., additional, Guerreiro, Marina, additional, Duarte, Filipe J. S., additional, Freire, Carmen S. R., additional, Calhorda, Maria José, additional, Silvestre, Armando J. D., additional, Kunz, Werner, additional, Rebelo, Luís Paulo N., additional, and Silva Pereira, Cristina, additional

Published
2014
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