title: Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids.
abstract: 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.
authors.affiliation: 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.
authors.forename: Huiyang
authors.initials: H
authors.lastname: Bian
authors.affiliation: 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.
authors.forename: Liheng
authors.initials: L
authors.lastname: Chen
authors.affiliation: 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.
authors.forename: Ruibin
authors.initials: R
authors.lastname: Wang
authors.affiliation: Forest Products Laboratory, U.S. Forest Service, U.S. Department of Agriculture; jzhu@fs.fed.us.
authors.forename: Junyong
authors.initials: J
authors.lastname: Zhu
mesh_terms: D002483:Cellulose, Oxidized / Q000737:chemistry*; D003998:Dicarboxylic Acids / Q000737:chemistry*; D055772:Green Chemistry Technology; D006868:Hydrolysis; D053758:Nanoparticles / Q000737:chemistry*; D059027:Recycling
chemical_list: D002483:Cellulose, Oxidized; D003998:Dicarboxylic Acids