Characterization Utilization And Optimization Of Ethiopian Sugarcane Bagasse (saccharum Officinarum L.) For Pulp And Paper Making

The current global awareness about the use of non-wood biomass for pulp and paper production rnhas resulted in significant reduction of deforestation. Based on this, the dissertation investigated rnthe suitability of Ethiopian sugarcane bagasse (ESCB) (Saccharum officinarum L.) for the pulp rnand paper production. The study is focused toward the physical fractionation pretreatment of the rnEthiopian sugarcane bagasse aiming at the reduction of its lignin, extractive, silica, and ash rncontents to improve the pulping process. In this regard, chemical compositional analysis was rncarried out in order to determine the cellulose, lignin, holocellulose, ash and silica contents. rnFurthermore, cold, and hot water solubility, 1% NaOH solubility and the ethanol-toluene extractive rncontents were measured. The chemical composition analysis of Ethiopian sugarcane bagasse rnrevealed a good level of cellulose (50%) and Klason lignin content (18%). The measurement of rnthe bagasse fiber dimensions (fiber length of 1.86 mm, fiber diameter of 30.02 µm, cell-wall rnthickness of 2.53 µm) advocates its suitability for pulp and paper production. The physical rnfractionation pretreatment had a significant effect on reducing the lignin, ethanol-toluene rnextractive, ash, and silica contents in the Ethiopian sugarcane bagasse, as evidenced from the rnFourier Transform Infrared Spectroscopy analysis. rnBased on the above results, the physical fractionation pretreated Ethiopian sugarcane bagasse rn(ESCB-B) was further delignified by using soda and Kraft pulping methods followed by a single rnstage hydrogen peroxide bleaching. Multilevel categoric experimental design was used to assess rnthe effects of three independent process variables (pulping temperature, chemical concentration, and time) on the pulp yield and kappa number during the soda and Kraft pulping processes. rnResponse surface methodology with central composite experimental design was used to assess the rneffect of independent bleaching variables (bleaching temperature, H2O2 concentration and time) rnon the pulp yield, brightness, and whiteness during the bleaching process. For the optimal pulping rnoutputs, the pulp yield was 35.99% with 16.73 kappa number and 38.41% with 17.68 kappa rnnumber for soda and Kraft delignification, respectively. The bleaching response for soda pulp with rnkappa number of 16.73 and 8.27 were pulp yield of 88.07% and 85.17%, brightness of 62.02% rnand 71.86% and whiteness of 84.43% and 90.47%, respectively. The bleaching response for Kraft rnpulp with kappa number of 17.68 and 8.41 were pulp yield of 84.12% and 83.91%, brightness of rn61.92% and 68.35% and whiteness of 85.36% and 91.43%, respectively. Paper from soda pulp rnwith kappa number of 16.73 and Kraft pulp with kappa number of 17.68 had higher burst, tensile rnand tear strength than paper from soda pulp with kappa number of 8.27 and Kraft pulp with kappa rnnumber of 8.41. Results suggest that the utilization of Ethiopian sugarcane bagasse using soda and rnKraft delignification at the optimum conditions of 130 rnornC cooking temperature, 10% sodium rnhydroxide concentration at 60 min followed by single stage hydrogen peroxide bleaching is a rnpromising approach. rnFurthermore, the black liquors generated from the untreated and physical fractionation pretreated rnEthiopian sugarcane bagasse by using soda and Kraft delignification processes were characterized. rnThe lignin, chemical oxygen demand, biochemical oxygen demand and total dissolved solid rncontents of pretreated sugarcane bagasse soda and Kraft black liquor were found to be (28.45 g/L, rn50000 mg/mL, 328 mg/mL, 145.83 mg/L) and (23.29 g/L, 74100 mg/mL, 192 mg/mL, 157.49 rng/L), respectively. On the other hand, the lignin, chemical oxygen demand, biochemical oxygen rndemand and total dissolved solid contents of untreated sugarcane bagasse soda and Kraft black liquor were (40.53 g/L, 54300 mg/mL, 356 mg/mL, 157.88 g/L) and (36.51 g/mL, 77400 mg/mL, rn200 mg/mL, 164.86 g/L), respectively. The untreated sugarcane bagasse soda and Kraft black rnliquor present higher contents of lignin, chemical oxygen demand, biochemical oxygen demand rnand total dissolved solid than pretreated soda and Kraft black liquor. The physical fractionation rnpretreatment had a significant effect on reducing the lignin, chemical oxygen demand, biochemical rnoxygen demand and total dissolved solid contents of the black liquor. The results clearly rndemonstrate the efficacy of physical fractionation pretreatment for Ethiopian sugarcane bagasse rnfor pulp and paper production.

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