Fatigue and Aeronautical Material Research Group, Department of Materials and Technology, São Paulo State University (Unesp), School of Engineering, Guaratinguetá, 12516-410, São Paulo, Brazil.
Fatigue and Aeronautical Material Research Group, Department of Materials and Technology, São Paulo State University (Unesp), School of Engineering, Guaratinguetá, 12516-410, São Paulo, Brazil.
Carbohydr Res. 2021 Jan;499:108227. doi: 10.1016/j.carres.2020.108227. Epub 2020 Dec 23.
Recently, the growing environmental concerns and economic demands have driven the need to develop effective solutions for the treatment of vegetal fibers to be used as renewable source for various industrial applications. The present study aimed to explore pineapple crown fibers (PCs) as an alternative source of cellulose. The three treatments (alcohol-insoluble residue (AIR), alkaline (AT), and organosolv) evaluated promoted chemical and morphological changes to the PCs. Fresh and treated PCs were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), thermogravimetric analysis (TG), and chemical composition. The XRD results showed that the Cellulose-I allomorph was not altered during extraction, and that the crystallinity index of the fibers treated with AT, first bleaching step, second bleaching step, and the second bleaching step followed by KOH treatment (2B_KOH) increased to 77.8; 83.2; 83.5 and 86% when compared with fresh PC (62.3%). Results from the thermal analysis revealed that thermal stability increased for the isolated cellulose, and the maximum degradation for (2B_KOH) is 350 °C. Chemical composition results showed a decrease in the content of hemicellulose, lignin and other soluble materials after alkaline treatment, suggesting high-quality 2B_KOH with 74.6% of cellulose. SEM revealed changes in the morphological structure on fibers. Alkaline treatment followed by HO bleaching is an excellent alternative for the removal of non-cellulosic material and facilitates the isolation of cellulose. These results suggested that there is a potential to isolate cellulose from PC via the sequence of treatment of a methodology by chlorite-free.
最近，不断增长的环境问题和经济需求推动了开发有效方法的需求，以便将植物纤维处理为可再生资源，用于各种工业应用。本研究旨在探索菠萝冠纤维（PCs）作为纤维素的替代来源。评估的三种处理方法（醇不溶残渣（AIR）、碱性（AT）和有机溶剂法）促进了 PCs 的化学和形态变化。新鲜和处理过的 PCs 通过傅里叶变换红外光谱（FTIR）、X 射线衍射（XRD）、扫描电子显微镜（SEM）、热重分析（TG）和化学成分进行了表征。XRD 结果表明，在提取过程中纤维素-I 同晶型没有改变，并且用 AT、第一漂白纸浆、第二漂白纸浆和第二漂白纸浆后用 KOH 处理（2B_KOH）处理的纤维的结晶度指数增加到 77.8%、83.2%、83.5%和 86%，而新鲜 PC 为 62.3%。热分析结果表明，分离纤维素的热稳定性提高，（2B_KOH）的最大降解温度为 350°C。化学成分结果表明，碱性处理后半纤维素、木质素和其他可溶性物质的含量下降，表明 2B_KOH 具有 74.6%的纤维素，质量较高。SEM 显示纤维的形态结构发生了变化。碱性处理后用 HO 漂白纸浆是去除非纤维素材料的极好方法，并有助于纤维素的分离。这些结果表明，通过无氯二氧化氯处理的方法序列，有可能从 PCs 中分离出纤维素。
