Kinetics and mechanism of hemicelluloses removal from cellulosic fibers during the cold caustic extraction process.
The effective separation of hemicelluloses and cellulose is desirable for the production of high-purity cellulose, which is a sustainable raw material for many value-added applications. For this purpose, the kinetics and mechanism of hemicelluloses removal from the cold caustic extraction (CCE) were investigated in the present study. The hemicelluloses removal process consists of: 1) the bulk phase, characteristic of significant hemicelluloses removal; 2) the transition phase, hemicelluloses transferring from the inner to the outer region of the fiber wall, with negligible overall hemicelluloses removal; 3) the residual phase, presenting a weak but continuing hemicelluloses removal. Furthermore, the enzymatic peeling method was adopted to study the fundamentals of hemicelluloses removal. The results showed that the molecular weight of hemicelluloses is the main parameter governing their diffusion/dissolution processes, and that the low molecular weight hemicelluloses are preferentially removed.
College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada; Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education/Shandong Province, Qilu University of Technology, Jinan 250353, China.
Jianguo
J
Li
College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
Huichao
H
Hu
Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada; Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin 300457, China.
Hailong
H
Li
College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Liulian
L
Huang
College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Lihui
L
Chen
College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. Electronic address: yonghao@unb.ca.
Yonghao
Y
Ni
D002424:Caustics; D002482:Cellulose / Q000737:chemistry*; D004058:Diffusion; D007700:Kinetics; D008970:Molecular Weight; D011134:Polysaccharides
D002424:Caustics; D011134:Polysaccharides; D002482:Cellulose
Cold caustic extraction; Hemicellulose removal; Hemicelluloses distribution; Kinetics and mechanism; Molecular weight