Exploring Sudanese agricultural residues as alternative fibres for pulp and paper manufacturing

In this work, the chemical composition, fibre dimensions and morphology, elemental analysis and paper characterisation of sesame, millet, karkadeh and sorghum stalks were studied. Soda and soda-anthraquinone pulping as sulfur-free processes were applied. It was found that, the cellulose content of karkadeh, sesame, millet and sorghum stalks were 45.80, 42.30, 40.99 and 35.40%, respectively. Klason lignin was found to be highest in sesame 20.85% while it was 19.32, 18.20 and 10.32% in karkadeh, millet and sorghum, respectively. Moreover, karkadeh showed highest pulp yield (46.60% and 43.50%) with viscosity of (655 ml/g and 640 ml/g) and kappa number of (18.00 and 19.40) for soda-AQ and soda pulps, followed by sesame, okra and sorghum, respectively. Overall strength properties of the handsheet made from karkadeh pulp were significantly higher than those made from sesame, millet, and sorghum pulps. Morphological analysis and chemical composition of the studied fibrous materials showed their suitability for producing paper of various grades including writing and printing paper as well as packaging applications.