Vinhas Silvia, Sarraguça Mafalda, Moniz Tânia, Reis Salette, Rangel Maria
LAQV, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal.
LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
Polymers (Basel). 2023 Dec 20;16(1):20. doi: 10.3390/polym16010020.
An enormous interest in the development of efficient protocols for cellulose extraction has been demonstrated in the last few years, although usually based on non-sustainable chemical and thermal approaches. In this work, we propose a new and more sustainable method for cellulose extraction from eucalyptus and pine tree wood waste products exclusively performed using microwave-assisted radiation. The methodology includes three main steps: (i) alkaline treatment; (ii) bleaching I, using HO; and (iii) bleaching II, an acidic treatment. Samples obtained in each step were characterized by Fourier-transform Infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results were compared with the structural and thermal profile of the starting materials, a commercially available microcrystalline cellulose and with an industrial paper pulp sample. Results confirmed that for both types of wood wastes, cellulose was retained during the extraction procedures and that the removal of hemicellulose and lignin was mainly achieved in the last step, as seen by the FTIR spectra and TGA curves. The developed protocol is innovative, as it constitutes an easy and quick approach for extracting cellulose from eucalyptus and pine tree wood waste. Mild chemical and thermal conditions are used during the three extraction steps (microwave irradiation, aqueous solutions, maximum of 120 °C in a total of 3 h). Moreover, environmentally friendly purification steps are applied based on the use of water and ethanol. This approach offers the possibility of a future scale-up study to potentially apply the developed protocol to the extraction of cellulose on an industrial scale.
在过去几年中，人们对开发高效的纤维素提取方案表现出了极大的兴趣，尽管这些方案通常基于不可持续的化学和热方法。在这项工作中，我们提出了一种全新且更具可持续性的从桉木和松木废料中提取纤维素的方法，该方法完全采用微波辅助辐射进行。该方法包括三个主要步骤：（i）碱处理；（ii）使用过氧化氢进行第一次漂白；（iii）第二次漂白，即酸性处理。对每个步骤中获得的样品进行了傅里叶变换红外光谱（FTIR）、粉末X射线衍射（PXRD）、热重分析（TGA）和差示扫描量热法（DSC）表征。将结果与起始材料、市售微晶纤维素以及工业纸浆样品的结构和热特性进行了比较。结果证实，对于这两种类型的木材废料，在提取过程中纤维素得以保留，并且如FTIR光谱和TGA曲线所示，半纤维素和木质素的去除主要在最后一步实现。所开发的方案具有创新性，因为它是一种从桉木和松木废料中提取纤维素的简便快捷方法。在三个提取步骤（微波辐射、水溶液、总共3小时内最高120°C）中使用了温和的化学和热条件。此外，基于水和乙醇的使用应用了环保的纯化步骤。这种方法为未来的扩大研究提供了可能性，有可能将所开发的方案应用于工业规模的纤维素提取。
