Browsing by Author "Mata, Teresa M."
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- Acid pretreatment of sugarcane biomass to obtain hemicellulosic hydrolisate rich in fermentable sugarPublication . Morais Júnior, Wilson Galvão; Pacheco, Thályta F.; Corrêa, Priscila S.; Martins, António A.; Mata, Teresa M.; Caetano, NídiaThe objective of this work was to find the ideal pretreatment conditions with high efficiency to obtain a hydrolyzate rich in fermentable sugars and low possible inhibitors levels. Thus, it was applied diluted phosphoric acid to pretreat the sugarcane biomass. Through a Central Composite Design, it was evaluated the influence of temperature, operating time and acid concentration. The pretreatment efficiency was verified by the concentration of total monosaccharides in the liquid fraction after the reaction. The phosphoric acid concentration of 4.95% at 80 °C, during 375 min, resulted in a hemicellulosic hydrolyzate with the highest concentration of fermentable sugars (saccharification greater than 99%), with the absence of HMF and furfural, and relatively low amounts of acetic acid.
- Bioethanol from Brewers’ Spent Grain: Pentose FermentationPublication . Mata, Teresa M.; Tavares, Tomás F.; Meireles, Sónia; Caetano, Nídia SáThis work aims to perform a preliminary optimization of the fermentation of brewers’ spent grain (BSG) sugars to bioethanol, focusing on the pentose sugars. Firstly, it was conducted the acid pre-treatment and enzymatic hydrolysis for studying different reaction times and amounts of enzymes in order to convert cellulose and hemicelluloses into simple sugars. The greatest amount of total sugars achieved experimentally is 5.56 g/ 25g of dry BSG, corresponding to a sugars maximum conversion of 22.24 % from a BSG sample with about 6 % cellulose and about 40 % hemicelluloses. This was obtained by sequentially adding the acids HCl and HNO3 with 1 wt% of concentration to BSG to perform the pre-treatment, simultaneously with 1.0657 g of Glucanex 100g and 2.0 mL of Ultraflo L for the hydrolysis. Secondly, it was studied the fermentation step, using both synthetic medium and BSG hydrolyzate, and the yeasts Pichia stipitis NCYC 1541 (P. stipitis) and Kluyveromyces marxianus NYCY 2791 (K. marxianus). Results show that the fermentation efficiency of all sugars in the synthetic media is higher than 80_% for both yeasts, but in the BSG hydrolyzate it is just 45.10 %for P. stipitis and 36.58 % for K. marxianus for a 72 h fermentation time at a 30 °C temperature. The theoretical ethanol yield from BSG hydrolyzates is 0.27 and 0.19 g ethanol/ g of sugars for respectively, P. stipitis and K. marxianus, but the actual ethanol yield obtained in this work is 0.0856 and 0.0308 g ethanol/ g of sugars, respectively that is three times smaller than the theoretical yield for P. stipitis and six times smaller for K. marxianus, which can be attributed to the presence of inhibitors resulting from the previous steps.
- Biofixation of CO2 emissions from natural gas combined cycle power plantPublication . Oliveira, Gisela M.; Caetano, Nídia; Mata, Teresa M.; Martins, António A.The growing impacts of climate change mainly due to the increasing emissions of GHG, especially carbon dioxide, has led to the development and implementation of specific strategies and policies to reduce them. Carbon capture and utilization (CCU) is currently seen as a good option, as it contributes to reduce the net carbon emissions and fulfil the goals of the Paris Agreement. This work analyses the economic potential of CO2 biofixation by microalgae from the exhaust gas of a Portuguese Natural Gas Combined Cycle (NGCC) power plant. Literature and real operational data are used, collected from reports of Portuguese power generation companies. A preliminary design and economic analysis of the carbon biofixation system was done. Results show that, although requiring a very large investment, the process is economically viable. In further studies a more in depth approach and detailed project combined with a sensitivity analysis, and a comparison with the chemical based CO2 fixation will be done.
- Biotechnological potential of Phaeodactylum tricornutum for biorefinery processesPublication . Branco-Vieira, Monique; San Martin, Sergio; Agurto, Cristian; Freitas, Marcos A.V.; Martins, António A.; Mata, Teresa M.; Caetano, NídiaMicroalgae are a rich source of proteins, carbohydrates and lipids, among other components, and thus, are considered to be the next generation biomass. However, in order to enhance the economic viability of its industrial production, all biomass components need to be valorized, requiring a multi-product biorefinery. Thus, this work proposes and conceptually analyses biorefinery processes for valorizing Phaeodactylum tricornutum for biofuels and high-value compounds, based on real data from a pilot-scale process. The algal biomass was biochemically characterized and the production was scaled-up to an industrial approach to analyze three biorefinery configurations, based on a 18 ton·year−1 of microalga biomass. The biomass revealed a composition of 7.85 wt% carbohydrates, 38.40 wt% proteins, 9.08 wt% lipids, 0.86 wt% fucoxanthin and 5.19 wt% biosilica. The biorefinery process addressed for biofuels production has an estimated annual production of 1.72, 0.35 and 1361 m3·year−1 of respectively biodiesel, bioethanol and biomethane. The biorefinery addressed for high-value compounds yields 0.18, 0.93 and 6.95 ton·year−1 of respectively fucoxanthin, biosilica and protein. The biorefinery designed for valorizing full microalgae biomass, showed to be more beneficial for promoting a circular economy. Biorefinery approach is useful for making sound and profitable decisions regarding microalgae bioproducts.
- Comparison of allocation approaches in soybean biodiesel life cycle assessmentPublication . Morais, S.; Martins, A. A.; Mata, Teresa M.This work shows the influence of using different allocation approaches when modelling the inventory analysis in a soybean biodiesel life cycle assessment (LCA). Results obtained using mass, energy and economic based allocations are compared, focusing on the following aspects: normalised potential environmental impact (PEI) categories, total PEI and relative contributions to the total PEI from each life cycle stage and environmental impact category. Similar results are obtained either using economic and energy based allocations. However, different results are obtained when mass based allocation is used when compared with the other two. This study also illustrates that using different allocation approaches in biodiesel LCA may influence the final conclusions, especially in comparative assertions, emphasising the need to perform a sensitivity analysis in the LCA interpretation step.
- Composition, cultivation and potential applications of Chlorella zofingiensis – A comprehensive reviewPublication . Gorgich, Malihe; Martins, António A.; Mata, Teresa M.; Caetano, NídiaChlorella zofingiensis has been in the center of attention due to its viability of cultivation, capability to yield various products, and applicability in various industrial sectors. Several research studies have evaluated this microalga as a bio-factory for carotenoids and lipids production, which are interesting compounds for industrial applications. The microalgae's robustness to various environmental and stress conditions such as light, temperature, salinity, and nutrients' deficiency/excess promotes its importance as a promising source of the mentioned valuable products. Hence, this study intends to review the most prominent contents of C. zofingiensis (i.e., lutein, astaxanthin, exopolysaccharides or EPS, lipids, etc.) and analyze the cultivation and stress conditions which directly influence the quality and quantity of the desired compounds. Upon review, discussions will be conducted to investigate the ability to combine stress factors to increase the contents of interest. Following an investigation over the composition and content induction approaches, several commercial applications of this microalga will be listed and explained, in particular, to obtain valuable products which have been discussed. These applications are chosen to cover multiple sectors, from medical and pharmaceutical, to food and feedstock, biofuel and energy, and wastewater treatment. The broad capability and robustness of C. zofingiensis make it a suitable investment to target more than one sector. Finally, it is discussed and presented a tentative design of a pipeline combining several applications to increase the economic viability of obtaining multiple products.
- Enhancing extraction and purification of phycocyanin from Arthrospira sp. with lower energy consumptionPublication . Gorgich, Malihe; Passos, Marieta L.C.; Mata, Teresa M.; Martins, António A.; Saraiva, M. Lúcia M.F.S.; Caetano, NídiaPhycocyanin is a light-blue water-soluble natural pigment with wide application in fields including pharmaceutical, cosmetic and food industry. Arthrospira platensis is considered a natural bio-factory for obtaining phycocyanin, and although suitable cultivation conditions can enhance the pigment content, the importance of extraction and purification should not be overlooked, because the chemicals used in those steps can affect the quality of phycocyanin. Further, changes in temperature, or approaches used to extract other protein types from biomass, have been reported to degrade phycocyanin, influencing its final quality, while also contributing to higher energy consumption in the extraction process. Hence, this work compares several approaches for phycocyanin extraction, and analyzed the effects of changes in operating conditions, such as exposure time, application of solvent buffer, and ultrasonication, on the extraction yield, the extracts purity, and the process energy use efficiency. Experimental results point to promising improvements in the extraction yield with high purity of phycocyanin (44.24 mg/g with purity ratio of 0.34), when suitable operating parameters were used (2 h exposure to potassium phosphate buffer with 20 min of ultrasonication).
- Evaluation of Areca palm renewable options to replace disposable plastic containers using life cycle assessment methodologyPublication . Gautam, Anirudh; Mata, Teresa M.; Martins, António A.; Caetano, NídiaIn spite of raising awareness of the environmental impacts associated to the production and utilization of plastics, in many situations, the use of plastics is advantageous, and options are still unavailable or under development, representing an opportunity to develop more sustainable options, such as less energy intensive solutions. In this work, the LCA methodology is used to evaluate the environmental impacts of boxes, bowls and plates produced using Areca palm (Areca catechu) sheath, a waste material common in southern India. The inventory is a combination of primary data from a company in India, complemented with secondary data from the Ecoinvent v2.1 (Simapro V7.3). Results show that the main contributors to the potential environmental impact categories and the most energy intensive life cycle steps, are transportation, shipping and electricity generation. Carbon footprints of 1180, 1033 and 1090 kg CO2eq/ton were obtained for Areca boxes, plates and bowls, respectively. Plates made from Areca palm sheath have lower environmental impacts than plastic plates, except in the ozone layer depletion and terrestrial toxicity impact categories.
- Fish Oil Enzymatic Esterification for Acidity ReductionPublication . Mata, Teresa M.; Correia, Daniela; Andrade, Soraia; Casal, Susana; Ferreira, Isabel M. P. L. V. O.; Matos, Elisabete; Martins, António A.; Caetano, NídiaThe reduction of the fish oil acidity is a significant problem in the rendering industry, as the oil’s range of applications and market value strongly depend on this parameter. In particular, the lower the acidity, the larger the oil’s market value. This work aims to study the potential of enzymatic esterification for reducing the fish oil acidity, by converting the free fatty acids into esters. Thus, four commercial lipases were used and a parametric study was performed to identify the best operating conditions, varying the reaction temperature, enzyme/oil mass ratio and alcohol/FFA mass ratio. All experiments were performed in duplicate with a very good reproducibility of results. Results showed that Lipozyme TL 100L contributed to greater acidity reduction (75% from an initial acid value of 10–14 mg KOH/g oil) for esterification at 40 °C, using ethanol 96% v/v, enzyme/oil and alcohol/FFA mass ratios of 0.01 and 3.24 w/w, respectively, reaching 3.13 mg KOH/g oil of final acid value or 1.57% FFA content. The reaction kinetics were also studied and it was found that a second order rate law as a function of the alcohol and oil concentrations is more adequate, with 35.44 kJ/mol of activation energy and 1.94 × 103 L mol− 1 min− 1 of pre-exponential factor. In conclusion, this work shows that the enzymatic esterification to reduce the fish oil acidity is technically feasible, increasing its market value.
- Indoor Air Quality Improvement Using Nature-Based Solutions: Design Proposals to Greener CitiesPublication . Mata, Teresa M.; Oliveira, Gisela M.; Monteiro, Helena; Silva, Gabriela Ventura; Caetano, Nídia; Martins, António A.Low indoor air quality is an increasingly important problem due to the spread of urbanization. Because people spend most of their time inside, poor indoor air quality causes serious human health issues, resulting in significant economic losses. In this work, the current state of affairs is presented and analyzed, focusing on the current problems and the available solutions to improve the quality of indoor air, and the use of nature-based solutions. These involve the cultivation of microalgae in closed photobioreactors. In these systems, photosynthetic organisms can capture CO2 and other pollutants generated in indoor environments, which they use to grow and develop biomass. Several possible layouts for the implementation of microalgae-based indoor air cleaning systems are presented, taking into account the systems that are currently available at a commercial scale. A critical analysis of the microalgae indoor purification systems is presented, highlighting their advantages and disadvantages, and suggesting potential improvements and future lines of research and development in the area
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