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Projeto de investigação
A greener platform to design bio-based polymeric structures with therapeutic properties for biomedical applications
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Bacterial cellulose production through the valorization of waste apple pulp and stale bread
Publication . Esmail, Asiyah; Morais, Maria; Yilmazer, Ugur D.; Neves, Luísa A.; Freitas, Filomena; DQ - Departamento de Química; UCIBIO - Applied Molecular Biosciences Unit; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; LAQV@REQUIMTE; Springer Verlag
In this work, stale bread and waste apple pulp were used as feedstocks for the production of bacterial cellulose (BC). A glucose-rich solution was prepared from stale bread by dilute acid hydrolysis, while an extract comprising fructose and glucose was obtained from the waste apple pulp, which was used for cultivating Komagataeibacter xylinus DSM 2004, either as sole feedstocks or supplemented with Hestrin-Schramm medium. Supplementation significantly improved BC production: 3.38 ± 0.09 g/L for waste apple pulp extract and 2.07 ± 0.22 g/L for stale bread hydrolysate. There was no significant impact on BC chemical structure or fiber diameter, but the biopolymer produced from waste apple pulp extract had slightly higher crystallinity (CI = 59–69%) and lower thermal degradation temperature (Tdeg = 341–350 ℃) than that of the stale bread hydrolysate (CI = 55%; Tdeg = 316–320 ℃). Moreover, supplementation of the waste apple pulp extract led to the preparation of thicker membranes, with higher Young’s modulus, tension, and deformation at break but lower water uptake capacity and lower permeability to O2 and CO2. These results show that waste apple pulp and stale bread are suitable feedstocks for BC production and the cultivation conditions can be adjusted for tailoring the biopolymer’s mechanical and barrier properties to suit different applications.
A greener route to prepare PEBAX®1074 membranes for gas separation processes
Publication . Ortiz-Albo, Paloma; Alves, Vítor D.; Kumakiri, Izumi; Crespo, João; Neves, Luísa A.; DQ - Departamento de Química; LAQV@REQUIMTE; Elsevier
The solvent used in membrane fabrication is crucial for a potential industrial application, with a direct effect on its safety, environmental and economic impact. Thus, in the last years, the search for greener and safer solvents became of utmost importance aiming for a sustainable fabrication of highly performing membranes, since that also affects the final membrane morphology. Typically, solvent evaporation-based methods are used for the preparation of membranes for gas separation processes, such as dip-coating and spray coating methods. The advantage of this approach relies on the possibility of using greener non-toxic solvents, such as water and ethanol. However, an alternative route might involve the use of phase inversion methods. In this procedure, the selection of the solvent will play an even more important role, with an impact on the gas separation membrane properties. Small defects or structural changes will decisively alter the final membrane performance. In this work, it is presented for the first time the alternative use of a non-toxic and eco-friendly solvent, Rhodiasolv®Polarclean, for the preparation of CO2-selective PEBAX®-based membranes using a hybrid phase inversion method. This preliminary study evaluates the relationship between the fabrication protocol, with the resulting structural, thermal, and mechanical membrane properties for self-standing membranes. The gas separation performance was tested for different gases: H2, N2, O2, CO2 and CH4. This analysis also includes a comparison with the commonly used, although strongly restricted and hazardous, solvent N-Methyl-2-Pyrrolidone (NMP).
Extraction and Characterization of Cellulose Obtained from Banana Plant Pseudostem
Publication . Nascimento, Rosa E. A.; Carvalheira, Mónica; Crespo, João G.; Neves, Luísa A.; DQ - Departamento de Química; LAQV@REQUIMTE; UCIBIO - Applied Molecular Biosciences Unit; MDPI - Multidisciplinary Digital Publishing Institute
Each year, the amount of residue generated from food production increases, caused by the continuous population growth. Banana is one of the most consumed fruits in the world, with an annual production of 116.78 million tonnes. However, just 12 wt% of the plant, corresponding to the bunch, is effectively used. After the bunch is harvested, the rest of the plant is disposed of as residue, the pseudostem (PS) being the main constituent. Aiming to give an added-value application to the PS, this work is focused on the extraction of cellulose from this waste. For this, three different fractions of PS particles—a non-classified fraction (milled but without sieving), a fine fraction (≤180 μm), and a coarse fraction (≥2000 μm)—and three extraction methods—alkaline-acid hydrolysis, enzymatic hydrolysis, and TEMPO oxidation—were studied to determine the most promising method for the cellulose extraction from the PS. The alkaline-acid hydrolysis samples presented a higher number of amorphous compounds, resulting in lower crystallinity (13.50% for the non-classified fraction). The TEMPO-oxidation process, despite allowing the highest cellulose extraction yield (25.25 ± 0.08% on a dried basis), resulted in samples with lower thermal stability (up to 200 °C). The most promising extraction method was enzymatic, allowing the extraction of 14.58 ± 0.30% of cellulose (dried basis) and obtaining extracts with the highest crystallinity (68.98% for the non-classified fraction) and thermal stability (until 250 °C).
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
CEEC IND5ed
Número da atribuição
2022.00689.CEECIND/CP1725/CT0017