Structural characterization of cellulose nanofibers isolated from spent coffee grounds and their composite films with poly(vinyl alcohol): a new non-wood source
Structural characterization of cellulose nanofibers isolated from spent coffee grounds and their composite films with poly(vinyl alcohol): a new non-wood source
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DOI：
10.1007/s10570-020-03113-w
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发表时间：
2020-04-01
期刊：
影响因子：
5.7
通讯作者：
Kawamura, Izuru
中科院分区：
文献类型：
--
作者：
Kanai, Noriko;Honda, Takumi;Kawamura, Izuru
废咖啡渣（SCG），这是在世界各地获得大量的新的非木材来源的废物价值已被考虑。通过2，2，6，6-四甲基哌啶-1-氧自由基（克里思）介导的含10%纤维素（干重）的SCG的氧化，已经成功地制备了衍生自SCG的纤维素纳米纤维。通过扫描电子显微镜观察，TEMPO氧化纤维素纳米纤维（TOCNFs）为20-35 nm宽。X射线衍射显示TOCNF以纤维素晶型I存在。由衍射图案确定的对应于纤维宽度的平均晶体尺寸为4.2nm。固态NMR显示，半纤维素和木质素主要通过TEMPO介导的氧化从SCG中去除，但少量的三酰甘油仍留在TOCNFs中。TOCNFs的热重分析显示在251 ℃和267 ℃下热分解的两个主要步骤，其高于咖啡烘焙温度范围。此外，为了研究这些TOCNF与聚合物的相互作用，制备了具有聚（乙烯醇）作为水溶性聚合物的SCG衍生的TOCNF复合膜。我们发现TOCNFs成功地整合到聚合物中。本研究结果表明，SCGs可以用作木材作为生产TOCNFs的替代来源，从而有助于可持续绿色化学的发展。[图片]
The waste valorization of spent coffee grounds (SCGs), which are obtainable in large amounts worldwide for new non-wood source has been considered. Cellulose nanofibers derived from SCGs have been successfully produced by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation of SCGs containing 10% cellulose (dry weight). The TEMPO-oxidized cellulose nanofibers (TOCNFs) are 20-35 nm wide observed by scanning electron microscopy. X-ray diffraction showed that TOCNFs are present in a cellulose crystal form I. The average crystal size corresponding to a fiber width was 4.2 nm, as determined from the diffraction pattern. Solid-state NMR shows that hemicellulose and lignin were mostly removed from SCGs via TEMPO-mediated oxidation, but small amounts of triacylglycerols remained in the TOCNFs. Thermogravimetric analysis of TOCNFs showed two major steps of thermal decomposition at 251 degrees C and 267 degrees C, which were higher than the coffee roasting temperature range. Furthermore, in order to investigate an interaction of these TOCNFs with a polymer, a SCG-derived TOCNF composite film with poly(vinyl alcohol) as a water-soluble polymer was prepared. We found the TOCNFs were successfully integrated into the polymer. The outcome of this study indicated that SCGs could be used as well as wood as an alternative source for producing TOCNFs, thus contributing to the development of sustainable green chemistry.[GRAPHICS]