Sudanese Dicots as Alternative Fiber Sources for Pulp and Papermaking

The suitability of the stems from two Sudanese dicotyledonous annual plants, namely castor bean (Ricinus communis) and Leptadenia pyrotechnica (L. pyrotechnica) were investigated for pulp and papermaking. Chemical compositions, elemental analysis, fiber dimensions, paper physical properties and morphology revealed a relatively high α-cellulose content (46.2 and 44.3 %) and low lignin (19.7 and 21.7 %) in the stems of castor bean and L. pyrotechnica, respectively. The average fiber length of castor bean and L. pyrotechnica is 0.80 and 0.70 mm with fiber width of 16.30 μm and 18.20 μm, respectively, which makes them acceptable candidates. Soda-AQ pulping of castor bean stem led to a higher pulp yield of 43.2 % at kappa number 18.2 compared to 40.3 % at kappa 20.3 for L. pyrotechnica. This yield is less than that obtained for wood plants and similar to that observed for annual plants. Paper handsheets produced from castor bean showed better mechanical properties than L. pyrotechnica. SEM images indicated that the produced papers were quite homogeneous, compact, closely packed, and well assembled.