A rapid method for quantification of carboxyl groups in cellulose pulp

Abstract

Carbonyl and carboxyl groups are important components of bleached cellulosic pulp due to their significant effect on the mechanisms that cause paper aging. Pulp yellowing and the decrease in cellulose molecular weight during aging are usually linked to these two functional groups. Carbonyl groups initiate oxidative processes, but their effects are largely increased when carboxyl groups are also present in the pulp. This work presents an automated potentiometric method for quantitative determination of carboxyl groups in bleached kraft pulp. The results obtained were compared with those obtained by the TAPPI (T 237 om- 93) standard method using the same samples. A good correlation (r = 0.9956) was observed between the methods, where the automated potentiometric titration method is most attractive due to its simplicity of execution and a shorter time required for the analysis. This method can be easily applied to quality control of a large number of samples in an industrial environment.