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- Eco-friendly methods for extraction and modification of cellulose: an overviewPublication . Magalhães, Solange; Fernandes, Catarina; Pedrosa, Jorge F. S.; Alves, Luís; Medronho, Bruno; Ferreira, Paulo J. T.; Rasteiro, Maria da GraçaCellulose is the most abundant renewable polymer on Earth and can be obtained from several different sources, such as trees, grass, or biomass residues. However, one of the issues is that not all the fractionation processes are eco-friendly and are essentially based on cooking the lignocellulose feedstock in a harsh chemical mixture, such as NaOH + Na2S, and water, to break loose fibers. In the last few years, new sustainable fractionation processes have been developed that enable the obtaining of cellulose fibers in a more eco-friendly way. As a raw material, cellulose’s use is widely known and established in many areas. Additionally, its products/derivatives are recognized to have a far better environmental impact than fossil-based materials. Examples are textiles and packaging, where forest-based fibers may contribute to renewable and biodegradable substitutes for common synthetic materials and plastics. In this review, some of the main structural characteristics and properties of cellulose, recent green extraction methods/strategies, chemical modification, and applications of cellulose derivatives are discussed.
- On hair care physicochemistry: From structure and degradation to novel biobased conditioning agentsPublication . Fernandes, Catarina; Medronho, B.; Alves, Luís; Rasteiro, Maria GraçaHair is constantly exposed to various adverse external stimuli, such as mechanical or thermal factors, that may cause damage or cause it to lose its shine and smooth appearance. These undesirable effects can be minimized by using hair conditioners, which repair the hair and restore the smooth effect desired by the consumer. Some of the currently used conditioning agents present low biodegradability and high toxicity to aquatic organisms. Consumers are also becoming more aware of environmental issues and shifting their preferences toward natural-based products. Therefore, developing novel, sustainable, natural-based derivatives that can act as conditioning agents in hair care products and thus compete with the traditional systems obtained from non-renewable sources is highly appealing. This paper presents the key physicochemical aspects of the hair conditioning process, including hair structure and degradation, and reviews some of the new alternative conditioning agents obtained from natural resources.
- Enhancing cellulose and lignin fractionation from acacia wood: optimized parameters using a deep eutectic solvent system and solvent recoveryPublication . Magalhães, Solange; Aliaño González, María José; Rodrigues, Mariana; Fernandes, Catarina; Mendes, Cátia V. T.; Carvalho, Maria Graça V. S.; Alves, Luís; Medronho, Bruno; Rasteiro, Maria da GraçaCellulose 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 degrees 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.
- Lignin extraction from acacia wood: crafting deep eutectic solvents with a systematic D-optimal mixture-process experimental designPublication . Fernandes, Catarina; Aliaño González, María José; Gomes, Leandro Cid; Bernin, Diana; Gaspar, Rita; Fardim, Pedro; Reis, Marco S.; Alves, Luís; Medronho, Bruno; Rasteiro, Maria Graça; Varela, CarlaLignin 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 degrees 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.