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- Influence of Wood Chemical Composition on Liquefaction Efficiency and Polyurethane Foam Properties: A Study of Red Angico and MahoganyPublication . Emilly Silva; Gonçalves Oliveira Valente da Cruz-Lopes, Luísa Paula; Domingos, idalina; Fabricio Gonçalves; Bruna da Silva Cruz; Michelângelo Fassarella; Antônio Thiago de Almeida; Esteves, BrunoBiomass liquefaction is a thermochemical process that converts lignocellulosic materials into reactive liquid intermediates, enabling the production of bio-based polyols as a sustainable alternative to petroleum-derived chemicals. This study investigates the liquefaction of two lignocellulosic biomasses, Red Angico (Anadenanthera colubrina) and Mahogany (Swietenia macrophylla), using a glycerol–ethylene glycol polyalcohol system, chosen for its renewable origin and high solvating efficiency. The resulting polyols were used to produce polyurethane (PU) foams, and their properties were evaluated in relation to biomass composition. The chemical composition of each biomass significantly influenced its liquefaction behavior and polyol characteristics. Mahogany achieved higher liquefaction efficiency, whereas Red Angico polyols generated PU foams with superior mechanical performance, highlighting the influence of species-specific chemistry. Water content and isocyanate index were found to modulate foam structure and compressive strength. This work demonstrates how tailored liquefaction strategies using polyalcohol systems can optimize bio-based PU foam properties, providing a sustainable route for high-performance polymer materials.
- Olive Tree (Olea europaea) Pruning Autohydrolysis: FTIR Analysis, and Energy PotentialPublication . Domingos, idalina; Domingos Ferreira, Miguel; Ferreira, José; Esteves, BrunoOlive trees cultivated in the Viseu region (Portugal) were used in the present work. This study investigates the compositional characteristics and hydrothermal behavior of olive branches (OB) and olive leaves (OL) under autohydrolysis, aiming to assess their potential for biorefinery applications. Chemical analysis revealed that during autohydrolysis (140–180 ◦C, 15–30 min), OL exhibited greater solubilization than OB, consistent with their higher extractive content. Increasing the temperature promoted selective hemicellulose removal and partial cellulose degradation, leading to a relative enrichment of lignin in the solid residues. Nevertheless, the cellulose content of olive branches for 180 ◦C and 30 min hydrolysis increased. Fourier transform infrared spectroscopy confirmed progressive structural rearrangements, including enhanced hydroxyl exposure, carbonyl formation, and lignin condensation, indicating the transformation of the solid phase toward more aromatic and thermally stable structures. Autohydrolysis slightly increased the higher heating value of the solid residues while acid-catalyzed liquefaction markedly increased, exceeding those of both native and technical lignins. These results suggest extensive carbon enrichment and oxygen removal during liquefaction. Overall, autohydrolysis proved effective for hemicellulose solubilization and sugar recovery, while liquefaction favored energy densification and lignin condensation. The distinct behaviors of OB and OL highlight the importance of tailoring processing conditions to each feedstock type. Both materials show strong potential as renewable resources for bioenergy and value-added carbon-based products within an integrated olive biomass biorefinery framework
- From Invasion to Valorization: Adsorbent Applications of Acacia dealbata Biomass in PortugalPublication . Weber Macena, Morgana; Esteves, Bruno; Jackelline S. Pinto; Rui Novais; Ana P. F. Caetano; Lucas Grosche; Helena Pereira; Gonçalves Oliveira Valente da Cruz-Lopes, Luísa PaulaAcacia dealbata, an invasive species in Portugal, produces large amounts of residual biomass during control operations, thereby presenting challenges and opportunities for sustainable valorization. Heavy metal contamination, including zinc (Zn), remains a critical environmental challenge due to its widespread industrial release and potential ecotoxicological impacts. This study explores the potential use of A. dealbata biomass as a biosorbent for zinc removal from aqueous solutions, comparing the performance of natural biomass and A. dealbata charcoal fines. Adsorption isotherms, kinetics, and surface characterizations were conducted to evaluate their physicochemical properties and sorption efficiency. The A. dealbata charcoal fines exhibited a significantly higher specific surface area (33 m2 g −1 ) and total pore volume (0.030 cm3 g −1 ) compared with the untreated biomass (1.4 m2 g −1 and 0.004 cm3 g −1 , respectively). Despite these structural differences, both materials demonstrated similar maximum adsorption capacities (23.36 and 23.79 mg g−1 for natural and charcoal fines, respectively). These results indicate that untreated A. dealbata biomass can perform as a biosorbent comparably to its carbonized form, representing a simple, low-cost, and sustainable alternative for heavy metal removal, offering a low-energy and sustainable alternative for Zn remediation.
- Liquefaction of Ruscus aculeatus Branches into Bio-Polyols: Process Optimization and Polyol CharacterizationPublication . Yuliya Dulyanska; Gonçalves Oliveira Valente da Cruz-Lopes, Luísa Paula; Fábio Bernardo; Dmitry V. Evtuguin; de Pinho Ferreira Guiné, Raquel; Gonçalves, Fernando Jorge; Luís A. E. Batista de Carvalho; Maria João Barroca; Esteves, BrunoThe conversion of lignocellulosic biomass into bio-polyols through liquefaction has attracted increasing interest as a sustainable route for polymer feedstock production. The liquefaction of Ruscus aculeatus L. branches was investigated to identify optimal processing conditions and to evaluate the properties of the resulting bio-polyols. The effects of temperature, reaction time, particle size, and material-to-solvent ratio on liquefaction yield were systematically studied. Liquefaction yield increased markedly with temperature, reaching up to 92% at 180 °C after 60 min of reaction, while reaction time showed only a marginal effect beyond 15 min. Smaller particle sizes and higher solvent ratios improved liquefaction efficiency, with optimal conditions identified between 1:7 and 1:10 material-to-solvent ratios. The hydroxyl number decreases with increasing liquefaction temperature due to dehydration and condensation reactions. Thermal and rheological analyses indicated improved thermal stability and increased viscosity at higher liquefaction temperatures. These results highlight the potential of Ruscus aculeatus branches as a promising renewable feedstock for bio-polyol production and polyurethane applications.
- Estudos preliminares de Adsorventes Lenhocelulósicos para a Remoção de CefalosporinasPublication . Gonçalves Oliveira Valente da Cruz-Lopes, Luísa Paula; Araújo, R.; Lopes, Ana Rita Valente da Cruz; Weber Macena, Morgana; Esteves, BrunoIntrodução: A Acacia dealbata foi explorada como biosorvente para remover cefalosporina de soluções aquosas. Este estudo procura demonstrar a viabilidade de utilizar materiais lenhocelulósicos de baixo custona remoção de poluentes, valorizando resíduos de outras indústrias e reduzindo o impacto ambiental associado. Objetivo: O objetivo pretendeu avaliar a capacidade dos resíduos de acácia em adsorver a cefalosporina, analisando o seu potencial de adsorção e os modelos cinéticos envolvidos, de forma a explorar o seu uso no tratamento de águas. Métodos: Esta revisão foi conduzida utilizando uma abordagem sistemática para identificar, analisar e sintetizar a literatura relevante sobre a presença e o impacto dos antibióticos cefalosporínicos em ambientes aquáticos. Paralelamente, foram realizados testes de adsorção utilizando soluções de cefalosporina com concentração de 15 mg L⁻¹, variando o tempo de agitação entre 10 e 120 minutos. A cinética de adsorção foi avaliada com base nos modelos de pseudo-primeira ordem, pseudo-segunda ordem, Elovich e difusão intrapartícula. A adsorção foi analisada através de espectrometria UV-Vis, onde se identificou um pico de absorção característico a 240 nm. Resultados: Os resultados indicaram que o modelo de pseudo-primeira ordem apresentou o coeficiente de determinação mais elevado (R² = 0,991), sugerindo que o mecanismo predominante é a adsorção física. Esta análise confirmou a capacidade da acácia em adsorver cefalosporinas, evidenciando o seu potencial como biosorvente. Conclusão: Este estudo sublinha a relevância dos biosorventes, como a Acacia dealbata, no tratamento de poluentes da indústria farmacêutica. A utilização de materiais sustentáveis oferece uma solução promissora para o tratamento de águas, abrindo caminho para futuras aplicações no campo da biossorção.
- Chemical Modification of Pachira aquatica Oil for Bio-Based Polyurethane Wood AdhesivesPublication . Silva, Emilly; Esteves, Bruno; Domingos, idalina; Almeida, Margarida Lopes de; Araújo, Bruno; Chaves, Izabella; Fassarella, Michelângelo; et al.The development of biomass-based adhesives has attracted interest as an alternative to petroleum-derived synthetic and potentially toxic adhesives. Pachira aquatica oil is a renewable raw material that can be incorporated into an MDI-based polyurethane system. In this study, the chemical composition and reactivity of P. aquatica oil were characterized using GC–MS, FTIR, and hydroxyl index measurements. The oil showed a predominance of saturated fatty acids, particularly methyl hexadecanoate (64.80%), derived from palmitic acid, and exhibited a low initial hydroxyl value. To enhance reactivity, the oil was transesterified with glycerol under different conditions, producing polyols with substantially increased hydroxyl values (412–769 mg KOH g−1 ), as confirmed by the intensified O–H and C–O bands in the FTIR spectra. The polyurethane adhesives were formulated from the selected polyols (P3 and P4) and evaluated at different NCO/OH ratios and pressing temperatures, using ABES shear tests. The highest ABES shear strength recorded was approximately 3.6 MPa, obtained for isocyanate indices between 0.8 and 1.0 and temperatures around 115 ◦C. Although this value represents the best performance among the tested conditions, it remains below the industrial benchmarks typically associated with the EN 205 standard (≈10 MPa). It is important to note that the ABES and EN 205 methods are not directly comparable due to differences in testing protocols. Nevertheless, the results indicate that, under the evaluated conditions, the adhesives exhibit limited mechanical performance and require further optimization.
- Characterization of Lignocellulosic Byproducts from the Portuguese Forest: Valorization and Sustainable UsePublication . Macena, Morgana; Gonçalves Oliveira Valente da Cruz-Lopes, Luísa Paula; Grosche, Lucas; Santos-Vieira, Isabel; Esteves, Bruno; Pereira, HelenaThe increasing emphasis on environmental sustainability has placed biomass as a versatile and renewable resource, while the management and disposal of forest byproducts remain a significant challenge. This study explores the valorization of forest biomass residues derived from Pinus pinaster, Pinus pinea, and the invasive species Acacia dealbata, with a focus on their potential application as bioadsorbents. A comprehensive physicochemical characterization was conducted for different biomass fractions (leaves, needles, and branches of varying diameters). Leaves and needles contained higher amounts of extractives (from 7.7% in acacia leaves to 18.8% in maritime pine needles) and ash (3.4 and 4.2% in acacia leaves and stone pine needles, respectively), whereas branches contained more holocellulose (from 59.6% in P. pinea small branches to 79.2% in P. pinaster large branches). ATR-FTIR and pHpzc analyses indicated compositional and surface charge differences, with higher pHpzc values in A. dealbata relative to Pinus. TG analysis showed that acacia large branches degraded at a lower temperature (320 °C) compared to Pinus species (440–450 °C). Overall, the findings highlight the suitability of these underutilized forest byproducts as bioadsorbents, contributing to the advancement of circular economy practices.
- Environmental and Economic Assessment of Desktop vs. Laptop Computers: A Life Cycle ApproachPublication . Domingos Ferreira, Miguel; Domingos, idalina; Leite dos Santos, Lenise Maria; Barreto Ana; Ferreira, JoséThis study evaluates and compares the environmental and economic implications of desktop and laptop computer systems throughout their life cycles using screening life cycle assessment (LCA) and life cycle costing (LCC) methodologies. The functional unit was defined as the use of one computer system for fundamental home and small-business productivity tasks for over four years. The analysis considered the production, use, and end-of-life phases. The results showed the desktop system had a higher overall carbon footprint (679.1 kg CO2eq) compared to the laptop (286.1 kg CO2eq). For both systems, manufacturing contributed the largest share of the emissions, followed by use. Desktops exhibited significantly higher use phase emissions, due to greater energy consumption. Life cycle cost analysis revealed that laptops had slightly lower total costs (EUR 593.88) than desktops (EUR 608.40) over the 4-year period, despite higher initial investment costs. Sensitivity analysis examining different geographical scenarios highlighted the importance of considering regional factors in the LCA. Manufacturer-provided data generally showed lower carbon footprint values than the modeled scenarios. This study emphasizes the need for updated life cycle inventory data and energy efficiency improvements to reduce the environmental impacts of computer systems. Overall, laptops demonstrated environmental and economic advantages over desktops in the defined usage cases.
- Olive Tree (Olea europaea) Pruning: Chemical Composition and Valorization of Wastes Through LiquefactionPublication . Domingos, idalina; Domingos Ferreira, Miguel; Ferreira, José; Esteves, Bruno; MDPIOlive tree branches (OB) and leaves (OL) from the Viseu region (Portugal) were studied for their chemical composition and liquefaction behavior using polyalcohols. Chemical analysis revealed that OL contained higher ash content (4.08%) and extractives, indicating more bioactive compounds, while OB had greater α-cellulose (30.47%) and hemicellulose (27.88%). Lignin content was higher in OL (21.64%) than OB (16.40%). Liquefaction experiments showed that increasing the temperature from 140 ◦C to 180 ◦C improved conversion, with OB showing a larger increase (52.5% to 80.9%) compared to OL (66% to 72%). OB reached peak conversion faster, and the optimal particle size for OB was 40–60 mesh, while OL performed better at finer sizes. OL benefited more from higher solvent ratios, whereas OB achieved high conversion with less solvent. FTIR analysis confirmed that acid-catalyzed liquefaction breaks down lignocellulosic structures, depolymerizes cellulose and hemicellulose, and modifies lignin, forming hydroxyl, aliphatic, and carbonyl groups. These changes reflect progressive biomass degradation and the incorporation of polyalcohol components, converting solid biomass into a reactive, polyol-rich liquid. The study highlights the distinct chemical and processing characteristics of olive branches and leaves, informing their potential industrial applications.
- Life Cycle Assessment of Pig Production in Central Portugal: Environmental Impacts and Sustainability ChallengesPublication . Leite dos Santos, Lenise Maria; Domingos Ferreira, Miguel; Domingos, idalina; Oliveira Verónica; Rodrigues Carla; Ferreira António; Ferreira, José; MDPIPig farming plays a crucial socioeconomic role in the European Union, which is one of the largest pork exporters in the world. In Portugal, pig farming plays a key role in regional development and the national economy. To ensure future sustainability and minimize environmental impacts, it is essential to identify the most deleterious pig production activities. This study carried out a life cycle assessment (LCA) of pig production using a conventional system in central Portugal to identify the unitary processes with the greatest environmental impact problems. LCA followed the ISO 14040/14044 standards, covering the entire production cycle, from feed manufacturing to waste management, using 1 kg of live pig weight as the functional unit. The slurry produced is used as fertilizer in agriculture, replacing synthetic chemical fertilizers. Results show that feed production, raising piglets, and fattening pigs are the most impactful phases of the pig production cycle. Fodder production is the stage with the greatest impact, accounting for approximately 60% to 70% of the impact in the categories analyzed in most cases. The environmental categories with the highest impacts were freshwater ecotoxicity, human carcinogenic toxicity, and marine ecotoxicity; the most significant impacts were observed for human health, with an estimated effect of around 0.00045 habitants equivalent (Hab.eq) after normalization. The use of more sustainable ingredients and the optimization of feed efficiency are effective strategies for promoting sustainability in the pig farming sector.