Kinetic Study of the Acetylation of Cotton Linter Pulp

Peicheng Luo, Cuicui Cao, Yinchun Liang, Xiaolong Ma, Chuanxian Xin, Zhen Jiao, Jianhua Cao, Jie Zhang

Abstract


The kinetics of the reaction of cotton linter pulp with acetic anhydride catalyzed by sulfuric acid at temperatures ranging from 30 to 45 °C have been investigated. A kinetic model considering the dissolution of the sufficiently sulfated cellulose chains on the surface of the solid fibers, and the subsequent reactions in the liquid phase was proposed for the acetylation process. The kinetic parameters were regressed from the measured degree of substitution using a nonlinear regression method. With the optimum values of the rate constants, the proposed model can predict the acetylation process very well. The chemical activation energy of the reactions of the cellulose hydroxyl groups with acetic anhydride was estimated as 39.6 kJ/mol. The dissolution rate of the sulfated chains can be represented by the equation r/r0=1-kt. A similar equation, the Arrhenius expression, k=Aexp(-E/RT) was used to predict the dissolution rate constants. The corresponding activation energy for the dissolution was evaluated as 19.6 kJ/mol.

Keywords


Acetylation; Cotton linter; Cellulose acetate; Kinetics; Modeling; Dissolution

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