Role of ethoxide ion in soda-ethanol pulping of Egyptian bagasse

Abstract EN

Role of ethoxide ion in alkaline-ethanol pulping was studied by the application of mild soda pulping conditions to prehydrolysed bagasse and monitoring the changes in pulp properties as a function of the concentration of ethanol.

Low concentration levels of ethoxide resulted in the cellulose supramolecular structure to become more amorphous and enhanced dissolution of shortchain carbohydrates by increasing the susceptibility of the pulp towards alkali.

Thus, high-alpha pulp with improved accessibility and chemical reactivity to xanthation were obtained.

Higher ethoxide concentration levels decreased the degree of pulping {de lignification), lowered the alpha-cellulose content and decreased the accessibility of the pulp.

These effects are attributed to a combination of: a) degradation of long-chain alpha-cellulose, b) the inability of ethoxide ion, compared to hydroxide ion to penetrate into the original native structure of the fibres thus leading to insufficient degree of pulping and, c) the self-condensation of lignin, catalysed by ethoxide ion.

The addition of anthraquinone (AQ) to the alkaline ethanol pulping liquors.

permitted the retention of different amounts of hemicellulose and lignin.