Bian Huiyang, Chen Liheng, Wang Ruibin, Zhu Junyong
Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University; Forest Products Laboratory, U.S. Forest Service, U.S. Department of Agriculture.
State Key Lab of Pulp and Paper Engineering, South China University of Technology; Forest Products Laboratory, U.S. Forest Service, U.S. Department of Agriculture.
J Vis Exp. 2017 Jan 9(119):55079. doi: 10.3791/55079.
Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils (CNF) from bleached eucalyptus pulp (BEP) and unbleached mixed hardwood kraft pulp (UMHP) fibers using highly recyclable dicarboxylic solid acids. Typical operating conditions were acid concentrations of 50 - 70 wt% at 100 °C for 60 min and 120 °C (no boiling at atmospheric pressure) for 120 min, for BEP and UMHP, respectively. The resultant CNCs have a higher thermal degradation temperature than their corresponding feed fibers and carboxylic acid group content from 0.2 - 0.4 mmol/g. The low strength (high pKa of 1.0 - 3.0) of organic acids also resulted in CNCs with both longer lengths of approximately 239 - 336 nm and higher crystallinity than CNCs produced using mineral acids. Cellulose loss to sugar was minimal. Fibrous cellulosic solid residue (FCSR) from the dicarboxylic acid hydrolysis was used to produce carboxylated CNFs through subsequent mechanical fibrillation with low energy input.
在此，我们展示了使用高度可回收的二羧酸固体酸，从漂白桉木浆（BEP）和未漂白混合硬木硫酸盐浆（UMHP）纤维中，以潜在低成本且绿色的方式生产高热稳定性的羧化纤维素纳米晶体（CNCs）和纳米纤维（CNF）。典型的操作条件是，BEP和UMHP分别在100°C下酸浓度为50 - 70 wt% 60分钟，以及在120°C（常压下不沸腾）下120分钟。所得的CNCs具有比其相应原料纤维更高的热降解温度，羧酸基团含量为0.2 - 0.4 mmol/g。有机酸的低强度（高pKa为1.0 - 3.0）还导致所得CNCs的长度约为239 - 336 nm，比使用无机酸生产的CNCs更长，结晶度更高。纤维素向糖的损失最小。二羧酸水解产生的纤维状纤维素固体残渣（FCSR）通过后续低能量输入的机械原纤化用于生产羧化CNF。
