Exploiting the Amazonian Açaí Palm Leaves Potential as Reinforcement for Cement Composites through Alkali and Bleaching Treatments

ABSTRACT

Recent investigations proposed alternatives for utilization of Açaí (Euterpe oleracea Mart.) fruit wastes, seeds, and lignocellulosic fibers. However, Açaí leaves may also be obtained without harvesting the palms and could be used in higher value-added products. Alkali reaction (1% and 5% of NaOH), different temperatures (70°C, 80°C, and 100°C), and bleaching were combined to produce fibres from the Açaí leaves. Scanning electron microscopy, X-ray diffraction, and thermogravimetry were used to evaluate the effect of treatments on fibers, whereas X-ray diffraction and calorimetry were employed to characterize Portland cement pastes containing fibers. Results indicated that Açaí leaves could be transformed into short-length fibers with improved degrading temperature. Alkali treatment at 5% sodium hydroxide (90°C) and bleaching increased fibers’ crystallinity and showed efficiency in removing non-cellulosic components. Cement paste evaluation also indicated that fibers treated at 5% NaOH solution caused fewer changes in calorimetric profile and therefore present a greater potential for cement-based composites.

摘要

最近的调查提出了一种新的能源利用方法Açaí (果实废料、种子和木质纤维。然而，也可以不收割棕榈而获得Açaí叶，并且可以用于高附加值产品. 碱反应（1%和5%氢氧化钠），不同温度（70°C、 80个°C、 和100°C），和漂白相结合，从Açaí 树叶. 扫描电子显微镜、X射线衍射和热重分析用于评估处理对纤维的影响，而X射线衍射和量热分析用于表征含有纤维的硅酸盐水泥浆体. 结果表明，Açaí 随着降解温度的提高，叶片可以转化为短纤维. 5%氢氧化钠（90%）碱处理°C） 漂白提高了纤维的结晶度，对非纤维素组分有较好的去除效果. 水泥浆体评价还表明，在5%NaOH溶液中处理的纤维对量热曲线的影响较小，因此对水泥基复合材料具有更大的潜力.

KEYWORDS:

• Biomass
• fiber morphology
• thermal stability
• biocomposite
• ceramic-matrix
• Portland cement

关键词:

• 生物量
• 纤维形态
• 热稳定性
• 生物复合材料
• 陶瓷基体
• 硅酸盐水泥

Acknowledgments

The authors are grateful to the Amapá Research Foundation (FAPEAP) for the financial support (First Projects Program – Process Number 250.203.044/2017), to the Coordination for the Improvement of Higher Level Personnel (CAPES) for the scholarships, the State University of Amapá (UEAP), Federal Rural University of Amazonia (UFRA), and to the Brazilian Agricultural Research Corporation (EMBRAPA), for the analyses and facilities.