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- Special issue CHEMPOR 2023 – 14th International Chemical and Biological Engineering ConferencePublication . Pinho, Simão; Barreiro, FilomenaThe 14th International Chemical and Biological Engineering Conference (CHEMPOR 2023), organized by Bragança Polytechnic University and the Portuguese Engineers Association, was held in Bragança, Portugal, on September 12–15, 2023. CHEMPOR 2023 focused on recent developments in various settings, including biorefinery, biotechnology, energy and environment, innovative materials, and the creation and design of novel reaction and separation processes, always foreseeing industrial applications for a sustainable future. The conference served as a melting pot to celebrate creativity, diversity, and friendship among participants, fostering the exchange of ideas and enabling fruitful interactions. It brought together professionals from the academic, industrial, scientific, and technological communities, uniting over 300 delegates from 12 countries. This collection of papers from CHEMPOR 2023 vividly illustrates how biological and chemical engineers are tackling the major societal challenges of our time. They highlight converging initiatives to promote sustainability through a circular economy where materials are valued and renewable. The papers present contemporary contributions in wastewater treatment, waste and biomass valorization, energy transition solutions, efforts to mitigate climate change, and bio-based approaches to produce, separate, and purify valuable compounds using ionic liquids or eutectic solvents. The selected works featured in this special issue represent an excellent reflection of the conference spirit. The attendees' dedication to seeking innovative solutions and producing high-quality scientific outputs also stood out. Finally, we want to express our profound appreciation to all the participants and our enormous gratitude to all our sponsors and associated scientific journals and publishers. In particular, we acknowledge the editorial team of Separation and Purification Technology, especially Bart Van der Bruggen and Raquel Aires-Barros, for their significant support and enthusiasm.
- Enhanced Antimalarial Activity of Extracts of Artemisia annua L. Achieved with Aqueous Solutions of Salicylate Salts and Ionic LiquidsPublication . Ferreira, Ana M.; Sales, Isabela; Santos, Sónia A.O.; Santos, Tiago; Nogueira, Fátima; Mattedi, Silvana; Pinho, Simão; Coutinho, João A.P.; Freire, Mara G.Artemisinin, a drug used to treat malaria, can be chemically synthesized or extracted from Artemisia annua L. However, the extraction method for artemisinin from biomass needs to be more sustainable while maintaining or enhancing its bioactivity. This work investigates the use of aqueous solutions of salts and ionic liquids with hydrotropic properties as alternative solvents for artemisinin extraction from Artemisia annua L. Among the investigated solvents, aqueous solutions of cholinium salicylate and sodium salicylate were found to be the most promising. To optimize the extraction process, a response surface method was further applied, in which the extraction time, hydrotrope concentration, and temperature were optimized. The optimized conditions resulted in extraction yields of up to 6.50 and 6.44 mg·g-1, obtained with aqueous solutions of sodium salicylate and cholinium salicylate, respectively. The extracts obtained were tested for their antimalarial activity, showing a higher efficacy against the Plasmodium falciparum strain compared with pure (synthetic) artemisinin or extracts obtained with conventional organic solvents. Characterization of the extracts revealed the presence of artemisinin together with other compounds, such as artemitin, chrysosplenol D, arteannuin B, and arteannuin J. These compounds act synergistically with artemisinin and enhance the antimalarial activity of the obtained extracts. Given the growing concern about artemisinin resistance, the results here obtained pave the way for the development of sustainable and biobased antimalarial drugs. © 2024 The Authors. Co-published by Zhejiang University and American Chemical Society.
- Special issue CHEMPOR 2023 – 14th International Chemical and Biological Engineering ConferencePublication . Pinho, Simão; Barreiro, FilomenaThe 14th International Chemical and Biological Engineering Conference (CHEMPOR 2023), organized by Bragança Polytechnic University and the Portuguese Engineers Association, was held in Bragança, Portugal, on September 12–15, 2023. CHEMPOR 2023 focused on recent developments in various settings, including biorefinery, biotechnology, energy and environment, innovative materials, and the creation and design of novel reaction and separation processes, always foreseeing industrial applications for a sustainable future. The conference served as a melting pot to celebrate creativity, diversity, and friendship among participants, fostering the exchange of ideas and enabling fruitful interactions. It brought together professionals from the academic, industrial, scientific, and technological communities, uniting over 300 delegates from 12 countries.
- Exploring the role of temperature on hydrotropyPublication . Abranches, Dinis O.; Soares, Bruna P.; Cordova, Isabella Weber; Benfica, Jordana; Ferreira, Olga; Pinho, Simão; Coutinho, João A.P.Aqueous solubility can be enhanced through hydrotropy, where an amphiphilic molecule (the hydrotrope) ag-gregates around the solute, boosting its solubility. To understand the impact of temperature on this phenomenon, the solubility of syringic acid was measured in aqueous solutions of different bio-based hydrotropes. Solubility curves were modelled using Gaussian processes, a powerful class of machine learning interpolators. This allowed for a thermodynamic analysis of excess solvation properties that was complemented using the COSMO-RS model. As expected, the absolute solubility of syringic acid increased with temperature. However, at low hydrotrope concentrations, this increase was not driven by interactions in the liquid phase. Thus, the solubility enhancement of syringic acid was found to be independent of temperature. Conversely, at high hydrotrope concentrations, increasing the temperature significantly decreased the solubility enhancement of the solute. These effects were interpreted considering different solubilization mechanisms, namely hydrotropy (low hydrotrope concentrations) and co-solvency (high hydrotrope concentrations).
- Thermodynamic description of aqueous solutions of silver nitrate: Experimental and modelingPublication . Arrad, Mouad; Aliyeva, Mehriban; Martins, Mónia A. R.; Thomsen, Kaj; Pinho, SimãoThe water activity of silver nitrate solutions was measured at 298.2 K and 313.2 K using a humidity sensor instrument. Concentrations of silver nitrate up to almost saturation were included. The thermodynamic properties of the system were described by the Pitzer model, the specific interaction theory (SIT), and the Extended UNIQUAC model. The interaction parameters for the models were estimated using experimental freezing points, osmotic coefficients, and solubility for silver nitrate aqueous solutions collected from the open literature, as well as the water activity data measured in this work. Pitzer and SIT parameters were applied by introducing a temperature dependency, enabling these models to cover a more comprehensive temperature range and extrapolate the calculation to higher molalities. Both approaches represent the data satisfactorily up to moderate molalities. The Extended UNIQUAC model, with its built-in temperature dependence, provides the best thermodynamic description of this binary system. It has a very satisfactory solubility diagram and a good description of the osmotic and activity coefficients.
- Extraction of phenolic compounds from Juglans regia L. leaves using aqueous solutions of eutectic solventsPublication . Cordova, Isabella Weber; Oludemi, Taofiq; Vieira, Vanessa; Pires, Tânia C.S.P.; Pinho, Simão; Barros, Lillian; Ferreira, OlgaThe leaves of Juglans regia L. (walnut tree) are a rich source of bioactive phenolic compounds, particularly flavonoids and phenolic acids, which can be used in cosmetic applications due to their antioxidant properties. Conventionally, these compounds are extracted using volatile organic solvents. This study focuses on a more sustainable approach by designing a heat-assisted extraction process using aqueous solutions of eutectic solvents (ES) composed of cosmetic-compatible ingredients aiming for direct incorporation into cream formulations. In this context, aqueous solutions of the ES betaine + urea and betaine + 1,3-propanediol (PPD) were selected, considering their potential as cosmetic ingredients. The screening process targeted the maximum extraction yield of phenolic compounds (phenolic acids and flavonoids), quantified by HPLC-DAD. The selected variables were water content (25, 50 and 75 % in weight) and the molar proportion of the ES components. For comparison purposes, pure water was used as a reference solvent. The total phenolic content ranged between 5.5 and 14.6 mg/g of dry plant. Betaine:urea (2:1), betaine:PPD (1:2), betaine, and PPD, all with 50 % water mass percentage, were among those resulting in higher extraction yields and were further selected for bioactivity analysis. The system containing betaine presented the best antioxidant capacity, analysed through ferric reducing power, DPPH radical scavenging, and TBARS assays. The extracts obtained with PPD presented the highest antimicrobial activity against gram-positive and gram-negative bacteria, and yeast. The results show the potential of using binary aqueous mixtures of betaine, or 1,3-propanediol, which are simple ingredients in cosmetics formulations, to efficiently extract phenolic compounds from a natural matrix. Moreover, the bioactivity results, particularly in the antioxidant dimension, support using J. regia leaves as a source of natural antioxidants.
- Experimental and theoretical studies on water activity: aqueous solutions of amino acids with electrolytesPublication . Fernandes, Isa Cristiana Moreira; Vilarinho, Mário F.; Pinho, SimãoIn the recent past a considerable body of work has been published on the measurement of activity coefficients and solubility data in aqueous amino acid solutions containing electrolytes [1]. However, no information on water activity in this type of system has yet been published [2]. In this work water activity (aw) in DL-alanine, glycine or L-serine aqueous systems with ammonium sulfate, at 298.15 K, was measured. The LabMASTER-aw water activity instrument (Novasina, Switzerland) was used to perform the measurements. The instrument, with a controlled chamber temperature (± 0.2 K), shows high precision (± 0.001 aw units). The new experimental data was used to test different theoretical schemes such as Zdanovskii-Stokes-Robinson (ZSR) model [3] and its extension, or the Clegg-Seinfeld-Brimblecombe (CSB) approach [4], in the calculation of amino acid and electrolyte activity coefficients in those solutions. Comparisons between the different approaches are given.
- Insights into the chloride versus bromide effecton the formation of urea quaternary ammonium eutectic solventsPublication . Martins, Mónia A.R.; Abranches, Dinis O.; Silva, Liliana P.; Pinho, Simão; Coutinho, João A.P.The intermolecular interactions of urea and quaternary ammonium salts relevant to their thermodynamic nonideality were here investigated by measuring the solid-liquid equilibria of their binary mixtures. The experimental data revealed that the anion transfer between the quaternary ammonium salt and urea increases with increasing alkyl chain lengths, leading to negative deviations from ideality in the urea-rich side for [N4,4,4,4]- based systems. However, the use of bromides instead of chlorides dampens the nonideality of urea because of larger size and lower electronegativity of the anion. The behavior of urea when mixed with ChCl or ChBr was found to be remarkably different, indicating that its nonideality in the ChCl/urea eutectic solvent is governed by urea-chloride rather than hydroxyethyl-urea interactions. The conclusions presented highlight the contribution of charge delocalization in the formation of deep eutectic solvents of type III.
- Erratum: Solubilities of biologically active phenolic compounds: Measurements and modelingPublication . Queimada, António; Mota, Fátima L.; Pinho, Simão; Macedo, Eugénia A.
- Representation of salt solubility in mixed solvents: a comparison of thermodynamic modelsPublication . Pinho, Simão; Macedo, Eugénia A.A simple and accurate apparatus for the measurement of salt solubilities in mixed solvents by an analytical method is presented. Salt solubility data have been measured for the systems water/methanol/NaCl, water/methanol/KCl at 298.15 and 323.15 K and for the system water/ethanol/NaCl at 298.15, 323.15 and 348.15K.