Chemistry, Chemical Engineering, Physical and Theoretical Chemistry, Environmental Chemistry
59
Scopus Publications
Scopus Publications
Optimizing lignin cationization: Unveiling the impact of reaction conditions through multi-response analysis Catarina Fernandes, Leandro Cid Gomes, Diana Bernin, Luís Alves, Bruno Medronho, Maria Graça Rasteiro, Carla Varela Chemical Engineering Journal, 2025 Lignin, a natural and abundant biopolymer, holds great potential for cosmetic applications. However, its limited solubility and inherently negative charge restrict its use in certain formulations. This is particularly relevant for hair conditioning, where a positively charged polymer is preferred to effectively treat negatively charged damaged hair. To overcome this limitation, lignin extracted from acacia wood residues was chemically cationized, through an etherification reaction, using 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) as cationization agent. The cationization process was optimized through a full factorial design of experiments aiming to maximize both the degree of substitution (DS) and ζ-potential of the lignin derivatives, thereby obtaining more positively charged derivatives. The reaction parameters temperature and CHPTAC-to-lignin molar ratio were selected as independent variables to be optimized. Results revealed that the reaction temperature is the most relevant parameter for lignin cationization, showing a significant positive influence on lignin modification, while the CHPTAC-to-lignin ratio has no significant impact. Under optimal conditions, soluble derivatives with a DS of 0.61 ± 0.03 and a ζ-potential of 18.79 ± 0.30 mV were obtained, confirming the success of the reaction. This straightforward and efficient approach enhances acacia's lignin solubility and charge properties, broadening its application potential. In particular, it offers a promising alternative for hair conditioning, thus contributing to the sustainable development of bio-based cosmetic ingredients.
Innovative Approaches to Mitigating Microplastic Pollution in Effluents and Soils Solange Magalhães, Luís Alves, Bruno Medronho, Ida Svanedal, Magnus Norgren, Maria Graça Rasteiro Sustainability Switzerland, 2025 Microplastic pollution represents a significant environmental challenge, as microplastics accumulate in effluents and soils, causing serious risks to ecosystems and human health. Efficient removal of these contaminants is essential to mitigate their potential adverse effects. This review summarizes and critically analyses current methods for the removal of microplastics from effluents and soils, focusing on their effectiveness, advantages, and limitations. Conventional techniques—including filtration, flotation, chemical coagulation, flocculation, and adsorption—are discussed in the context of wastewater treatment and soil remediation. Emerging approaches, such as flocculation processes with special focus on the application of bio-based flocculants, are also highlighted as promising solutions. Key challenges in microplastic removal, including the diversity of microplastic types, their small size, and the complexity of environmental matrices, are addressed. This work intends to contribute to the urgent need for further research to develop more efficient and sustainable strategies for microplastic removal from environmental systems.
Effect of Chitosan Properties and Dissolution State on Solution Rheology and Film Performance in Triboelectric Nanogenerators Francisca Araújo, Solange Magalhães, Bruno Medronho, Alireza Eivazi, Christina Dahlström, Magnus Norgren, Luís Alves Gels, 2025 Chitosan films with potential application in triboelectric nanogenerators (TENGs) represent a promising approach to replace non-biobased materials in these innovative devices. In the present work, chitosan with varying molecular weights (MW) and degrees of deacetylation was dissolved in aqueous acetic acid (AA) at different acid concentrations. It was observed that the MW had a greater influence on the viscosity of the solution compared to either the acid concentration or deacetylation degree. Gel formation occurred in high-MW chitosan solutions prepared with low AA concentration. Films prepared from chitosan solutions, through solvent-casting, were used to prepare TENGs. The power output of the TENGs increased with higher concentrations of AA used in the chitosan dissolution process. Similarly, the residual AA content in the dried films also increased with higher initial AA concentrations. Additionally, hot-pressing of the films significantly improves the TENG power output due to the decrease in morphological defects of the films. It was demonstrated that a good selection of the acid concentration not only facilitates the dissolution of chitosan but also plays a key role in defining the properties of the resulting solutions and films, thereby directly impacting the performance of the TENGs.
Tailored cellulose-based flocculants for microplastics removal: Mechanistic insights, pH influence, and efficiency optimization Solange Magalhães, Magnus Norgren, Luís Alves, Bruno Medronho, Maria da Graça Rasteiro Powder Technology, 2025 This study explores the performance of novel cellulose-derived sustainable flocculants in the flocculation of different model microplastics (MPs), including polyethylene (PE), polyethylene terephthalate (PET) and polyvinyl chloride (PVC). The influence of key parameters, such as pH, flocculant structure and concentration was evaluated by Laser Diffraction Spectroscopy (LDS) and optical microscopy to access their effects on flocculation performance, kinetics and floc structure. The results reveal that a bioflocculant concentration of 0.001 g·mL −1 is ideal for effective flocculation, as lower concentrations lead to insufficient floc growth. While electrostatic interactions are a dominant factor in the flocculation process, the study also highlights the role of hydrophobic interactions, its contribution depending on the characteristics of the MPs. Overall, this research highlights the importance of understanding the key interactions governing the flocculation process. It further paves the way for designing and fine-tuning cellulose-based flocculants with improved efficiency and optimized dosages for effective MPs removal strategies. • Cellulose derivatives developed were used as flocculants in microplastics removal. • Bio-flocculants developed included both cationic and hydrophobic moieties. • MPs flocculation kinetics and evolution of flocs structure with time assessed by LDS. • It was possible to design the bio-flocculants to remove different types of model MPs.
Lignin-Furanic Rigid Foams: Enhanced Methylene Blue Removal Capacity, Recyclability, and Flame Retardancy Hugo Duarte, João Brás, El Mokhtar Saoudi Hassani, María José Aliaño-Gonzalez, Solange Magalhães, Luís Alves, Artur J. M. Valente, Alireza Eivazi, Magnus Norgren, Anabela Romano, Bruno Medronho Polymers, 2024 Worldwide, populations face issues related to water and energy consumption. Water scarcity has intensified globally, particularly in arid and semiarid regions. Projections indicate that by 2030, global water demand will rise by 50%, leading to critical shortages, further intensified by the impacts of climate change. Moreover, wastewater treatment needs further development, given the presence of persistent organic pollutants, such as dyes and pharmaceuticals. In addition, the continuous increase in energy demand and rising prices directly impact households and businesses, highlighting the importance of energy savings through effective building insulation. In this regard, tannin-furanic foams are recognized as promising sustainable foams due to their fire resistance, low thermal conductivity, and high water and chemical stability. In this study, tannin and lignin rigid foams were explored not only for their traditional applications but also as versatile materials suitable for wastewater treatment. Furthermore, a systematic approach demonstrates the complete replacement of the tannin-furan foam phenol source with two lignins that mainly differ in molecular weight and pH, as well as how these parameters affect the rigid foam structure and methylene blue (MB) removal capacity. Alkali-lignin-based foams exhibited notable MB adsorption capacity (220 mg g−1), with kinetic and equilibrium data analysis suggesting a multilayer adsorption process. The prepared foams demonstrated the ability to be recycled for at least five adsorption-desorption cycles and exhibited effective flame retardant properties. When exposed to a butane flame for 5 min, the foams did not release smoke or ignite, nor did they contribute to flame propagation, with the red glow dissipating only 20 s after flame exposure.
Stacking self-gluing cellulose II films: A facile strategy for the formation of novel all-cellulose laminates Christina Dahlström, Ran Duan, Alireza Eivazi, Solange Magalhães, Luís Alves, Magnus Engholm, Ida Svanedal, Håkan Edlund, Bruno Medronho, Magnus Norgren Carbohydrate Polymers, 2024 Cellulose laminates represent a remarkable convergence of natural materials and modern engineering, offering a wide range of versatile applications in sustainable packaging, construction, and advanced materials. In this study, novel all-cellulose laminates are developed using an environmentally friendly approach, where freshly regenerated cellulose II films are stacked without the need for solvents (for impregnation and/or partial dissolution), chemical modifications, or resins. The structural and mechanical properties of these all-cellulose laminates were thoroughly investigated. This simple and scalable procedure results in transparent laminates with exceptional mechanical properties comparable to or even superior to common plastics, with E-modulus higher than 9 GPa for a single layer and 7 GPa for the laminates. These laminates are malleable and can be easily patterned. Depending on the number of layers, they can be thin and flexible (with just one layer) or thick and rigid (with three layers). Laminates were also doped with 10 wt% undissolved fibers without compromising their characteristics. These innovative all-cellulose laminates present a robust, eco-friendly alternative to traditional synthetic materials, thus bridging the gap between environmental responsibility and high-performance functionality.
Customising Sustainable Bio-Based Polyelectrolytes: Introduction of Charged and Hydrophobic Groups in Cellulose Solange Magalhães, María José Aliaño-González, Pedro F. Cruz, Rose Rosenberg, Dirk Haffke, Magnus Norgren, Luís Alves, Bruno Medronho, Maria da Graça Rasteiro Polymers, 2024 Cellulose has been widely explored as a sustainable alternative to synthetic polymers in industrial applications, thanks to its advantageous properties. The introduction of chemical modifications on cellulose structure, focusing on cationic and hydrophobic modifications, can enhance its functionality and expand the range of applications. In the present work, cationization was carried out through a two-step process involving sodium periodate oxidation followed by a reaction with the Girard T reagent, yielding a degree of substitution for cationic groups (DScationic) between 0.3 and 1.8. Hydrophobic modification was achieved via esterification with fatty acids derived from commercial plant oils, using an enzyme-assisted, environmentally friendly method. Lipase-catalysed hydrolysis, optimised at 0.25% enzyme concentration and with a 1 h reaction time, produced an 84% yield of fatty acids, confirmed by FTIR and NMR analyses. The degree of substitution for hydrophobic groups (DShydrophobic) ranged from 0.09 to 0.66. The molecular weight (MW) of the modified cellulose derivatives varied from 1.8 to 141 kDa. This dual modification strategy enables the creation of cellulose-based polymers with controlled electrostatic and hydrophobic characteristics, customisable for specific industrial applications. Our approach presents a sustainable and flexible solution for developing cellulose derivatives tailored to diverse industrial needs.
Lignin extraction from acacia wood: Crafting deep eutectic solvents with a systematic D-optimal mixture-process experimental design Catarina Fernandes, M. J. Aliaño-González, Leandro Gomes, Diana Bernin, R. Gaspar, Pedro Fardim, Marco S. Reis, Luís Alves, B. Medronho, M. Rasteiro, Carla Varela International Journal of Biological Macromolecules, 2024 Lignin is a complex biopolymer whose efficient extraction from biomass is crucial for various applications. Deep eutectic solvents (DES), particularly natural-origin DES (NADES), have emerged as promising systems for lignin fractionation and separation from other biomass components. While ternary DES offer enhanced fractionation performance, the role of each component in these mixtures remains unclear. In this study, the effects of adding tartaric acid (Tart) or citric acid (Cit) to a common binary DES mixture composed of lactic acid (Lact) and choline chloride (ChCl) were investigated for lignin extraction from acacia wood. Ternary Cit-based DES showed superior performance compared to Tart-based DES. Using a combined mixture-process D-Optimal experimental design, the Lact:Cit:ChCl DES composition and extraction temperature were optimized targeting maximum lignin yield and purity. The optimal conditions (i.e., Lact:Cit:ChCl, 0.6:0.3:0.1 molar ratio, 140 °C) resulted in a lignin extraction yield of 99.63 ± 1.24 % and a lignin purity of 91.45 ± 1.03 %. Furthermore, this DES exhibited feasible recyclability and reusability without sacrificing efficiency. • Lignin extraction optimization via mixture-process experimental design • Ternary DES using lactic acid, citric acid and choline chloride • Lactic and citric acids content with high impact in extraction yield and purity • Synergistic effect of citric acid to improve extraction • Recovery and reuse of DES for three cycles without losing efficiency
Insights on Microplastic Contamination from Municipal and Textile Industry Effluents and Their Removal Using a Cellulose-Based Approach Solange Magalhães, Daniel Paciência, João M. M. Rodrigues, Björn Lindman, Luís Alves, Bruno Medronho, Maria da Graça Rasteiro Polymers, 2024 The rampant use of plastics, with the potential to degrade into insidious microplastics (MPs), poses a significant threat by contaminating aquatic environments. In the present study, we delved into the analysis of effluents from textile industries, a recognized major source of MPs contamination. Data were further discussed and compared with a municipal wastewater treatment plant (WWTP) effluent. All effluent samples were collected at the final stage of treatment in their respective WWTP. Laser diffraction spectroscopy was used to evaluate MP dimensions, while optical and fluorescence microscopies were used for morphology analysis and the identification of predominant plastic types, respectively. Electrophoresis was employed to unravel the prevalence of negative surface charge on these plastic microparticles. The analysis revealed that polyethylene terephthalate (PET) and polyamide were the dominant compounds in textile effluents, with PET being predominant in municipal WWTP effluents. Surprisingly, despite the municipal WWTP exhibiting higher efficiency in MP removal (ca. 71% compared to ca. 55% in textile industries), it contributed more to overall pollution. A novel bio-based flocculant, a cationic cellulose derivative derived from wood wastes, was developed as a proof-of-concept for MP flocculation. The novel derivatives were found to efficiently flocculate PET MPs, thus allowing their facile removal from aqueous media, and reducing the threat of MP contamination from effluents discharged from WWTPs.
Enhancing Cellulose and Lignin Fractionation from Acacia Wood: Optimized Parameters Using a Deep Eutectic Solvent System and Solvent Recovery Solange Magalhães, María José Aliaño-González, Mariana Rodrigues, Catarina Fernandes, Cátia V. T. Mendes, Maria Graça V. S. Carvalho, Luís Alves, Bruno Medronho, Maria da Graça Rasteiro Molecules, 2024 Cellulose and lignin, sourced from biomass, hold potential for innovative bioprocesses and biomaterials. However, traditional fractionation and purification methods often rely on harmful chemicals and high temperatures, making these processes both hazardous and costly. This study introduces a sustainable approach for fractionating acacia wood, focusing on both cellulose and lignin extraction using a deep eutectic solvent (DES) composed of choline chloride (ChCl) and levulinic acid (LA). A design of experiment was employed for the optimization of the most relevant fractionation parameters: time and temperature. In the case of the lignin, both parameters were found to be significant variables in the fractionation process (p-values of 0.0128 and 0.0319 for time and temperature, respectively), with a positive influence. Likewise, in the cellulose case, time and temperature also demonstrated a positive effect, with p-values of 0.0103 and 0.028, respectively. An optimization study was finally conducted to determine the maximum fractionation yield of lignin and cellulose. The optimized conditions were found to be 15% (w/v) of the wood sample in 1:3 ChCl:LA under a treatment temperature of 160 °C for 8 h. The developed method was validated through repeatability and intermediate precision studies, which yielded a coefficient of variation lower than 5%. The recovery and reuse of DES were successfully evaluated, revealing remarkable fractionation yields even after five cycles. This work demonstrates the feasibility of selectively extracting lignin and cellulose from woody biomass using a sustainable solvent, thus paving the way for valorization of invasive species biomass.
Probing cellulose amphiphilicity Bruno Medronho, Hugo Duarte, Luis Alves, Filipe Antunes, Anabela Romano, Björn Lindman Nordic Pulp and Paper Research Journal, 2015
