Studying the behaviors of cellulosic pulps through alkali refining in presence of anthraquinone

The role of anthraquinone (AQ) greatly depends on the nature of the cellulosic pulp during alkali refining. AQ acts in two ways; firstly penetration within the molecular chains separating them further apart leading to their decrystallisation; secondly stabilization of the polysaccharide chains. Cotton linter is known by its long macromolecular crystalline chains. The cold refining helps the swelling cotton linter and the penetration of AQ leads to decrystallisation of linter even at low AQ concentration (namely 0.025%). In comparison with paper Kraft pulp AQ does not reflect a considerable change on its characteristics, except on hot refining using higher AQ concentration (namely 0.2%). This is due to the nature opening structure of the paper Kraft pulp in addition to the hemicellulose content which preferentially stabilized by AQ giving a reasonable increase in the pentosan content. This is associated by improving in the reactivity towards xanthation.