Huang Deyuan, Hong Haoqun, Huang Weilong, Zhang Haiyan, Hong Xiaobin
School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China.
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China.
Polymers (Basel). 2021 Sep 15;13(18):3119. doi: 10.3390/polym13183119.
Waste paper is often underutilized as a low-value recyclable resource and can be a potential source of cellulose nanofibers (CNFs) due to its rich cellulose content. Three different processes, low acid treatment, alkali treatment and bleaching treatment, were used to pretreat the waste paper in order to investigate the effect of different pretreatments on the prepared CNFs, and CNFs obtained from bleached pulp boards were used as control. All sample fibers were successfully prepared into CNFs by 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) oxidation. It was quite obvious that the bleached CNFs samples showed dense fibrous structures on a scanning electron microscopy (SEM), while needle-like fibers with width less than 20 nm were observed on a transmission electron microscopy (TEM). Meanwhile, the bleaching treatment resulted in a 13.5% increase in crystallinity and a higher TEMPO yield (e.g., BCNF, 60.88%), but a decrease in thermal stability. All pretreated CNFs samples showed narrow particle size distribution, good dispersion stability (zeta potential less than -29.58 mV), good light transmission (higher than 86.5%) and low haze parameters (lower than 3.92%). This provides a good process option and pathway for scalable production of CNFs from waste papers.
废纸通常作为一种低价值的可回收资源未得到充分利用，由于其富含纤维素，它可能成为纤维素纳米纤维（CNF）的潜在来源。采用低酸处理、碱处理和漂白处理三种不同工艺对废纸进行预处理，以研究不同预处理对制备的CNF的影响，并将从漂白纸浆板获得的CNF用作对照。所有样品纤维均通过2,2,6,6-四甲基哌啶-1-氧基（TEMPO）氧化成功制备成CNF。很明显，在扫描电子显微镜（SEM）下，漂白的CNF样品呈现出致密的纤维结构，而在透射电子显微镜（TEM）下观察到宽度小于20nm的针状纤维。同时，漂白处理使结晶度提高了13.5%，TEMPO产率更高（例如，BCNF为60.88%），但热稳定性降低。所有预处理的CNF样品均表现出窄的粒度分布、良好的分散稳定性（zeta电位小于-29.58mV）、良好的透光率（高于86.5%）和低雾度参数（低于3.92%）。这为从废纸中规模化生产CNF提供了良好的工艺选择和途径。
