Hemida Mohamed H, Moustafa Hesham, Mehanny Sherif, Morsy Mohamed, Dufresne Alain, Abd El Rahman Eid N, Ibrahim M M
Agricultural Engineering Department, Faculty of Agriculture, Cairo University, Egypt.
Department of Polymer Metrology & Technology, National Institute of Standards (NIS), Tersa Street, El Haram, P.O Box 136, Giza, 12211, Giza, Egypt.
Heliyon. 2023 May 25;9(6):e16436. doi: 10.1016/j.heliyon.2023.e16436. eCollection 2023 Jun.
Extraction of cellulose nanocrystals (CNCs) from agro-residues has received much attention, not only for their unique properties supporting a wide range of potential applications, but also their limited risk to global climate change. This research was conducted to assess Nile roses () fibers as a natural biomass to extract CNCs through an acid hydrolysis approach. Nile roses fibers (NRFs) were initially subjected to alkaline (pulping) and bleaching pretreatments. Microcrystalline cellulose (MCC) was used as control in comparison to Nile rose based samples. All samples underwent acid hydrolysis process at a mild temperature (45 °C). The impact of extraction durations ranging from 5 to 30 min on the morphology structure and crystallinity index of the prepared CNCs was investigated. The prepared CNCs were subjected to various characterization techniques, namely: X-ray diffraction (XRD), FT-IR analysis, Transmission electron microscopy (TEM), and X-ray Photoelectron spectroscopy (XPS). The outcomes obtained by XRD showed that the crystallinity index increased as the duration of acid hydrolysis was prolonged up to 10 min, and then decreased, indicating optimal conditions for the dissolution of amorphous zones of cellulose before eroding the crystallized domains. These data were confirmed by FT-IR spectroscopy. However, a minor effect of hydrolysis duration on the degree of crystallinity was noticed for MCC based samples. TEM images illustrated that a spherical morphology of CNCs was formed as a result of 30 min acid hydrolysis, highlighting the optimal 20 min acid hydrolysis to obtain a fibrillar structure. The XPS study demonstrated that the main constituents of extracted CNCs were carbon and oxygen.
从农业废弃物中提取纤维素纳米晶体（CNCs）备受关注，这不仅是因为其独特性能支持广泛的潜在应用，还因其对全球气候变化的风险有限。本研究旨在评估尼罗玫瑰（）纤维作为天然生物质，通过酸水解方法提取CNCs。尼罗玫瑰纤维（NRFs）最初经过碱性（制浆）和漂白预处理。与基于尼罗玫瑰的样品相比，微晶纤维素（MCC）用作对照。所有样品在温和温度（45℃）下进行酸水解过程。研究了5至30分钟的提取时间对制备的CNCs的形态结构和结晶度指数的影响。对制备的CNCs进行了各种表征技术，即：X射线衍射（XRD）、傅里叶变换红外光谱分析（FT-IR）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）。XRD获得的结果表明，随着酸水解时间延长至10分钟，结晶度指数增加，然后下降，这表明在侵蚀结晶区域之前，纤维素无定形区域溶解的最佳条件。这些数据通过FT-IR光谱得到证实。然而，对于基于MCC的样品，水解时间对结晶度的影响较小。TEM图像表明，30分钟酸水解后形成了CNCs的球形形态，突出了20分钟酸水解以获得纤维状结构的最佳效果。XPS研究表明，提取的CNCs的主要成分是碳和氧。
