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2020
Cordeiro, T, Paninho AB, Bernardo M, Matos I, Pereira CV, Serra AT, Matias A, Ventura MG.  2020.  Biocompatible locust bean gum as mesoporous carriers for naproxen delivery. Materials Chemistry and Physics. 239:121973. AbstractWebsite

The work reports the impregnation of naproxen into locust bean gum mesoporous matrixes with different textural properties. The matrixes were prepared through the dissolution of the biopolymer in water and in two ionic liquids (ILs): [bmim][Cl] and [C2OHmim][Cl] and dried with scCO2. The poor water-soluble pharmaceutical drug naproxen was loaded into the matrixes and the composites were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy and by differential scanning calorimetry; the results were compared with neat ILs and drug. The naproxen release from the matrixes was attempted at pH 7.4. Sustained release of naproxen in the different composites occurs, and consequently the naproxen release has lower rates compared with neat crystalline naproxen dissolution. Nevertheless, it was possible to observe small differences on release profiles for the studied composites. The higher release rate was observed for the composite where [bmim][Cl] was used as solvent, for which the calorimetric analysis revealed full amorphization of the incorporated drug. Cytotoxicity assays reveal that cellular viability in Caco-2 cells is preserved. This fact allied with the biocompatibility of locust bean gum allow for the composites potential application as naproxen controlled/sustained delivery systems with higher drug bioavailability achieved through naproxen amorphization.

Rijo, B, Lemos F, Fonseca I, Vilelas A.  2020.  Development of a model for an industrial acetylene hydrogenation reactor using plant data – Part I. Chemical Engineering Journal. 379:122390. AbstractWebsite

In this work, a dynamic model of an industrial acetylene hydrogenation reactor with a front-end configuration was developed, based on plant operation data. This type of reactor operates in transient state, not only due to the natural fluctuations in operating conditions but also due to the effects caused by the deactivation of the catalyst. To develop the dynamic model of the acetylene hydrogenation reactor a thorough study of the effect of operating conditions was performed; the influence of variables such as the inlet temperature of the 1st reactor, the flowrate, carbon monoxide concentration, on the activity, selectivity and stability of the catalyst was examined by choosing adequate periods of the operation of the reactor. To understand the reaction mechanism of this system, several published kinetics were tested but only one was finally fitted to the industrial data, to interpret the operation of the acetylene hydrogenation reactor. A set of operation periods was used to develop the model which was then validated by applying the model to a different set of operation periods. As a conclusion, the dynamic model that was developed and validated, using actual plant operation data, was able to adequately describe the outlet temperatures of the three reactors in the system as well as the outlet acetylene concentration of the 3rd reactor.

Castanheiro, JE, Vital J, Fonseca IM, Ramos AM.  2020.  Glycerol conversion into biofuel additives by acetalization with pentanal over heteropolyacids immobilized on zeolites. Catalysis Today. 346:76-80. AbstractWebsite

Dodecamolydbophosphoric acid (HPMo) immobilized on USY zeolite was used as a catalyst for the acetalization of glycerol with pentanal at 70 °C. Catalysts were prepared with different amounts of heteropolyacid, and the most active sample was the HPMo2@Y catalyst (1.1 wt.%). The products of glycerol acetalization with pentanal were (2-butyl-1,3-dioxolan-4-yl)methanol, a five-member ring compound, and 2-butyl-1,3-dioxan-5-ol, a six-member ring compound. Good values of selectivity for the five-member ring compound (80–85%) were obtained with all materials. The reaction conditions were optimized using HPMo2@Y as a catalyst. The optimal conditions were determined to be 70 °C reaction temperature with 0.3 g catalyst and a 1:2.5 M ratio of glycerol to pentanal. The catalytic stability of HPMo2@Y was studied. The acetalization of glycerol with pentanal was performed using the same sample. High catalytic activity for HPMo2@Y was observed.

Agostinho, DAS, Paninho AI, Cordeiro T, Nunes AVM, Fonseca IM, Pereira C, Matias A, Ventura MG.  2020.  Properties of κ-carrageenan aerogels prepared by using different dissolution media and its application as drug delivery systems. Materials Chemistry and Physics. 253:123290. AbstractWebsite

This work reports the synthesis of kappa-carrageenan aerogels using different dissolution and crosslinking media in order to evaluate its effects on the textural properties of the matrixes and further on the drug loading and release performance. The different aerogel samples were produced through the dissolution of the biopolymer in water with addition of potassium salts as crosslinking agents and, in two different ionic liquids (ILs) derived from imidazolium ion, being further dried with supercritical CO2. The samples were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), Nitrogen Adsorption-Desorption Analysis, Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC). The synthesized samples presented surface areas similar to the carrageenan aerogels being their structure constituted mainly by meso and macropores. The absence of ionic liquid in samples was demonstrated by DSC analysis and was corroborated by the cytotoxicity assays which revealed that cellular viability in Caco-2 cells was preserved. Tetracycline was used as a model drug and loaded in two of the prepared aerogels samples. The release experiments were performed with the composites to test in vitro drug release at physiologic pH. With a higher macroporosity, the kappa-carrageenan aerogel prepared by dissolution into ionic liquid showed a higher loading capacity than the one prepared by dissolution into water and a slightly higher release rate. The matrixes were considered to present a good potential to be used as biocompatible carriers on drug controlled delivery.

2019
Castanheiro, JE, Vital J, Fonseca IM, Ramos AM.  2019.  Glycerol conversion into biofuel additives by acetalization with pentanal over heteropolyacids immobilized on zeolites. Catalysis Today. AbstractWebsite

Dodecamolydbophosphoric acid (HPMo) immobilized on USY zeolite was used as a catalyst for the acetalization of glycerol with pentanal at 70 °C. Catalysts were prepared with different amounts of heteropolyacid, and the most active sample was the HPMo2@Y catalyst (1.1 wt.%). The products of glycerol acetalization with pentanal were (2-butyl-1,3-dioxolan-4-yl)methanol, a five-member ring compound, and 2-butyl-1,3-dioxan-5-ol, a six-member ring compound. Good values of selectivity for the five-member ring compound (80–85%) were obtained with all materials. The reaction conditions were optimized using HPMo2@Y as a catalyst. The optimal conditions were determined to be 70 °C reaction temperature with 0.3 g catalyst and a 1:2.5 M ratio of glycerol to pentanal. The catalytic stability of HPMo2@Y was studied. The acetalization of glycerol with pentanal was performed using the same sample. High catalytic activity for HPMo2@Y was observed.

2018
Risso, R, Ferraz P, Meireles S, Fonseca I, Vital J.  2018.  Highly active Cao catalysts from waste shells of egg, oyster and clam for biodiesel production. Applied Catalysis A: General. 567:56-64. AbstractWebsite

Calcium oxide (CaO) catalysts derived from waste shells of egg, oyster and clam were prepared and used in the methanolysis of soybean oil. Eggshells were subjected to ultrasound irradiation and mollusc shells were subjected to calcination-hydration-calcination cycles to increase the surface area of CaO and improve its catalytic activity. The catalysts were characterized by XRD, TPD-CO2, TG-DSC, DLS and N2 adsorption, while the catalytic activity for the methanolysis of soybean oil was evaluated. Five hours of sonication reduced the CaO particle size by 34%, which resulted in a 56% increase in the activity. Two cycles of hydration-dehydration applied to the material obtained by calcination of oyster shells provided CaO with 27 m2 g−1. The transesterification rate was 2.5 times higher than that obtained with the untreated sample. After treatments, highly active CaO was obtained which indicates its enormous potential for biodiesel production. A kinetic model assuming the adsorption of methoxide anions on the surface of CaO particles was proposed.

Afonso, D, Ribeiro AFG, Araújo P, Vital J, Madeira LM.  2018.  Phenol in Mixed Acid Benzene Nitration Systems. Industrial & Engineering Chemistry Research. 57:15942-15953., Number 46 AbstractWebsite
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Madureira, J, Melo R, Verde SC, Matos I, Bernardo M, Noronha JP, Marga{\c c}a FMA, Fonseca IM.  2018.  Recovery of phenolic compounds from multi-component solution by a synthesized activated carbon using resorcinol and formaldehyde. Water Science and Technology. 77:456–466., Number 2: IWA Publishing AbstractWebsite

The adsorption of four phenolic compounds (gallic acid, protocatechuic acid, vanillic acid and syringic acid) is investigated using a synthesized mesoporous carbon on both single and multi-component synthetic solutions. Some correlation of the adsorption capacity of the carbon and the nature of adsorbate could be made, except for gallic acid whose concentration decrease seems to be not exclusively due to adsorption but also to polymerization reaction. In the multi-component mixture, negative effects in the adsorption capacity are observed probably due to competition for the active centers of the adsorbent surface. In desorption studies, ethanol presents better performance than water and acetonitrile. Vanillic acid is the compound with the higher adsorption and interestingly it is then possible to desorb a relatively high amount of it from the adsorbent, which may represent a possibility for a selective recovery of vanillic acid. These results present a potential way to treat the wastewater from the cork industry.

2017
Cordeiro, T, Castiñeira C, Mendes D, Florence Danède, Sotomayor J, Fonseca IM, Gomes da Silva M, Paiva A, Barreiros S, Cardoso MM, Viciosa MT, Correia NT, Dionisio M.  2017.  Stabilizing Unstable Amorphous Menthol through Inclusion in Mesoporous Silica Hosts. Molecular Pharmaceutics. 14:3164-3177., Number 9 AbstractWebsite
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Castanheiro, JE, Fonseca IM, Ramos AM, Vital J.  2017.  Tungstophosphoric acid immobilised in SBA-15 as an efficient heterogeneous acid catalyst for the conversion of terpenes and free fatty acids. Microporous and Mesoporous Materials. 249:16-24. AbstractWebsite

Alkoxylation of α−pinene, β−pinene and limonene was performed in the presence of SBA-15-occluded tungstophosphoric acid (HPW). The HPW was immobilised in SBA-15 using the sol-gel method. The catalysts were characterised by N2 adsorption, FT-IR, Raman spectroscopy, X-Ray diffraction, ICP-AES and TEM. A series of catalysts with different heteropolyacid loadings ranging from 1.8 to 19.3 wt. % were prepared. PW4-SBA-15 (with 10.8 wt. %) exhibited the highest catalytic activity for the alkoxylation of α-pinene with ethanol. An approximately 53% selectivity to α-terpinyl ethyl ether was observed over the PW-SBA-15 catalysts. PW4-SBA-15 was also used as a catalyst for the alkoxylation of other terpenes, including β-pinene and limonene. The PW4-SBA-15 catalyst exhibited high catalytic stability for the alkoxylation of α-pinene with ethanol. PW4-SBA-15 was also used as a catalyst for the esterification of free fatty acids (i.e., palmitic, stearic and oleic acids) with ethanol. Good catalytic activity was observed for the PW4-SBA-15 catalyst with the different substrates used in the esterifications.

2016
Cordeiro, T, Santos AFM, Nunes G, Cunha G, Sotomayor JC, Fonseca IM, Florence Danède, Dias CJ, Cardoso MM, Correia NT, Viciosa TM, Dionísio M.  2016.  Accessing the Physical State and Molecular Mobility of Naproxen Confined to Nanoporous Silica Matrixes. The Journal of Physical Chemistry C. 120:14390-14401., Number 26 AbstractWebsite

The pharmaceutical drug naproxen was loaded in three different silica hosts with pore diameters of 2.4 (MCM), 3.2 (MCM), and 5.9 nm (SBA), respectively: napMCM\_2.4 nm, napMCM\_3.2 nm, and napSBA\_5.9 nm. To access the guest physical state in the prepared composites, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy were used. The different techniques provided complementary information on a molecular population that was revealed to be distributed among different environments, namely the pore core, the inner pore wall, and the outer surface. It was found that naproxen is semicrystalline in the higher pore size matrix being able to crystallize inside pores; after melting it undergoes full amorphization. In the case of the lower pore size matrix, naproxen crystallizes outside pores due to an excess of filling while most of the remaining fraction is incorporated inside the pores as amorphous. Crystallinity in these two composites was observed by the emergence of the Bragg peaks in the XRD analysis, whereas for napMCM\_3.2 nm only the amorphous halo was detected. The latter only exhibits the step due to the glass transition by DSC remaining stable as amorphous at least for 12 months. The glass transition in the three composites is abnormally broad, shifting to higher temperatures as the pore size decreases, coherent with the slowing down of molecular mobility as probed by dielectric relaxation spectroscopy. For napSBA\_5.9 nm the dielectric response was deconvoluted in two processes: a hindered surface (S-) process due to molecules interacting with the inner pore wall and a faster α-relaxation associated with the dynamic glass transition due to molecules relaxing in the pore core, which seems a manifestation of true confinement effects. The drug incorporation inside a nanoporous matrix, mainly in 3.2 nm pores, was revealed to be a suitable strategy to stabilize the highly crystallizable drug naproxen in the amorphous/supercooled state and to control its release from the silica matrix, allowing full delivery after 90 min in basic media.