Extraction of Cellulose Nanofibrils (CNFs) from Pomelo Peel via a Green and Simple Method

ABSTRACT

Pomelo is cultivated worldwide due to its unique taste. Most of the pomelo peel is discarded, thus, wasting the beneficial ingredients contained in it. In order to effectively utilize these ingredients, a green and low-consumption method has been reported here to extract the cellulose nanofibrils (CNFs) from the pomelo peel by employing the sequential alkaline treatment, bleaching, acid hydrolysis, and ball milling. The results demonstrate that the impurities in the pomelo peel, such as hemicellulose and lignin, are gradually removed. The obtained CNFs still maintain their natural cellulose structure. The degree of crystallinity and thermal stability of CNFs are noted to be significantly improved as compared to the raw pomelo peel. The CNF diameter is observed to range between 6 and 47 nm. Compared with 10–17.5% NaOH/KOH and 60–65% HNO₃/H₂SO₄ used in previous studies, the developed method requires a low concentration of the alkali solution and bleaching agent. Further, the lemon juice, used as an acidolysis agent, is inexpensive and environmentally friendly. The ball milling purifies the CNFs and effectively reduces the size of CNFs without consuming a significant amount of energy. This study lays a foundation for an effective use of the agricultural solid waste based on pomelo peel.

摘要

柚子因其独特的口感而在世界范围内被广泛种植。大部分柚子皮都被丢弃了,从而浪费了其中所含的有益成分. 为了有效利用这些成分,本文报道了一种绿色、低消耗的方法,通过依次采用碱处理、漂白、酸水解、球磨等处理步骤从柚皮中提取纤维素纳米纤维 (CNF). 结果表明,柚皮中的半纤维素和木质素等杂质逐渐被去除. 得到的纤维素纳米纤维仍然保持其天然纤维素结构。与柚皮原料相比,CNF的结晶度和热稳定性显著提高. 制得的CNF直径在6-47 nm之间. 与先前研究中使用的10-17.5%NaOH/KOH和60-65%HNO3/H2SO4相比,开发的方法所需的碱溶液和漂白剂浓度较低. 此外,柠檬汁用作酸解剂,价格低廉且环保. 球磨可纯化CNF,并在不消耗大量能量的情况下有效减小CNF的尺寸. 该研究为柚子皮农业固体废弃物的有效利用奠定了基础.

KEYWORDS:

• Pomelo peel
• extraction
• cellulose nanofibrils
• lemon juice hydrolysis

关键词:

• 关键词
• 柚子皮
• 提取
• 纤维素纳米纤维
• 柠檬汁水解

Acknowledgments

This work was financially supported by　National　Key　Technology　R&D　Program (2019YFC1521302), Zhejiang Provincial Natural Science Foundation of China (LY19D030001), Zhejiang Provincial Administration of Cultural Heritage (No.2018012 and No. 2021015), The National Key Research and Development Program of China (2019YFC1521302), Scientific and Creative Personnel Special Support Program from ZheJiang Province (2017R52054).

Additional information

Funding

This work was supported by the National　Key　Technology　R&D　Program [2019YFC1521302]; Scientific and Creative Personnel Special Support Program from ZheJiang Province [2017R52054]; Zhejiang Provincial Natural Science Foundation of China [LY19D030001]; Zhejiang Provincial Administration of Cultural Heritage [No.2018012 ; No. 2021015]; The National Key Research and Development Program of China [2019YFC1521302].