Influence of Sequential Acid-alkali Treatment on Palm Biomass Waste Properties

ABSTRACT

Palm biomass (Archontophoenix alexandrae) is a natural crop of the food industry, even with a high potential to produce sustainable and innovative products. Thus, the purpose of this work was to evaluate the effect of sequential acid-alkali treatment followed by precipitation with concentrated H₂SO₄ on fiber’s microstructure, chemical, and physical properties. So, the raw fiber, the pre-treated fiber, and the precipitated lignin were characterized by scanning eléctron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Results indicated changes in lignocellulosic structure by SEM analysis, which confirms the defibrillation due to the reduction of the average diameter and lengths of treated fiber compared to raw fiber (~50%). FTIR and XRD also proved the partial removal of amorphous structures such as hemicellulose and lignin components, with changes in the intensity of absorption bands and the increase in the crystalline index after the sequential treatment (~58%). TGA and DTG analysis provided evidence of an enhancement in treated fiber and lignin’s thermal stability compared to raw fiber, confirming the adopted methodology’s efficiency to isolate the main lignocellulosic structures and disrupting the biomass recalcitrance.

摘要

芦苇（Phragmites spp.）和木荷（Hyphaene spp.）天然纤维; 博茨瓦纳本土建筑材料; 由于其理想的重量轻、机械性能和可回收性，是制造复合材料的潜在增强材料. 然而，对这些纤维的表面改性机理及其对其质量特性的影响尚不清楚. 本研究比较化学和热化学表面处理对纤维性能的影响. 此外，还确定了制备天然纤维增强聚合物复合材料（NFRPCs）的合适处理方法和纤维. 与化学处理相比，热化学处理能更有效地提高纤维的耐热性和力学性能. 水芦苇纤维经1.5wt.%NaOH溶液处理15d，然后在80°C下热处理24h，其质量特性（即抗拉强度（76.41mpa）、CI（59.2%）、CS（21.44nm）和降解温度范围288-598°C）最适合于建筑保温应用. 化学处理对纤维的表面改性机理是半纤维素的溶解，增加了纤维间的区域，而热处理的引入进一步促进了纤维素与半纤维素间键的断裂.

KEYWORDS:

• Biomass
• palm fiber
• lignocellulosic material
• treatment sequential
• diluted acid/alkaline pretreatment
• characterization

关键词:

• 莫柯尔万棕榈树
• 芦苇
• 纤维素纤维特性
• 碱处理
• 表面改性
• 红外光谱分析
• 扫描电镜分析
• 热重分析
• 射线衍射分析
• 单纤维拉伸试验

Acknowledgments

This research was funded by FAPERJ (E-26/010.101232/2018 and E-26/010.001800/2015).

Additional information

Funding

This work was supported by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro [(E-26/010.101232/2018 and E-26/010.001800/2015)].