Improved method for evaluation of cellulose degradation
Use of a fundamental concept, henceforth referred to as the scission fraction of cellulose unit (SFCU), was suggested to clarify the cleavage reactivity of cellulose during oxygen delignification (OD). According to the SFCU theory, the cleavage activity of pulp cellulose remains relatively undisturbed provided the experimental conditions are maintained regardless of pulp origin. SCFU is a universal variable for evaluating how processes and additives affect the degree of pulp cellulose degradation. Specifically in this study, the effects of the protector additives MgSO4 and phenol on the oxygen delignification (OD) process were investigated. Both phenol and MgSO4 retard the cleavage rate of the cellulose chain, but the retarding effect of MgSO4 is greater than that of phenol. Phenol alone cannot significantly improve the selectivity of the OD process, whereas MgSO4 can decrease the cleavage rate of cellulose and increase the selectivity of OD. Moreover, synergistic selectivity enhancement for pulp using a combination of MgSO4 and phenol was observed. The protective effect of various chemical protectors was additive, whereas the retarding effect on delignification was not.
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