| Wood characteristics of A.crassicarpa, A.mangium and A.cincinata such as fiber morphology,chemical composition, basic density, mechanical properties etc, which have significant impacton strength and optical properties of pulp made by chemi-mechanical pulping process, weredetermined and analyzed in this study. The pulping properties of three Acacia wood specieswere evaluated by testing specific energy consumption, strength properties and opticalproperties special for brightness of P-RC APMP pulp. Subsequently, process condition wasoptimized based on the previous experimental results and woodchips were pulped under theoptimization process to investigate the improvement on pulp properties and make a comparisonbetween Acacia species pulp properties. Meanwhile, contamination characteristics of effluentsfrom P-RC APMP pulping process using different chemical charges.In the study on wood characteristics, it is found that the mean fiber length of A.crassicarpawood is the longest and the shortest one is that of A.mangium wood, which are 1179.60μm and1066.44μm individually. A.mangium wood is of the greatest width of vessel 248.0μm, and thesmallest value of 199.4μm is measured from A.cincinata wood specimens. The Ruwkel ratiosof Acacia wood ranges from 0.48 to 0.75, in which A.mangium wood was tested for thesmallest volume of 0.48. Mmicrofibril angle of A.cincinata wood was found to be the highestwith the value of 18.86°and the lowest value of 11.94°was tested from A. crassicarpa wood. Inthe terms of chemical composition, the cellulose content of A. cincinata wood was more thanthe other two species but less for the lignin content. Meanwhile, the most contents of variousextractives were also evaluated for A.cincinata wood, except for its Alcohol-benzenesextractive. The testing results of basic density were 617 Kg/m3 of A.cincinata wood, 489Kg/m3 of A.crassicarpa wood and 415 Kg/m3 of A.mangium wood. Great discrepancy ofmechanical properties was found among Acacia wood samples, and the results indicated thatA.cincinata wood was of the highest values of mechanical indices; however the indices ofA.mangium wood were lowest.Strength properties of P-RC APMP pulp made from Acacia wood were found to arise with anincrease in the charge of NaOH, H2O2, meanwhile, energy consumption was reduced. Pulpproperties such as burst index, tensile index, tear index was improved after optimization ofprocess condition. Brightness of A.crassicarpa pulp went up to 78%ISO, 81%ISO for A. cincinata and 82％ISO for A. mangium. It was found that the lowest energy consumption,best strength properties and highest brightness was evaluated for A. mangium pulp bycomparison on pulp properties of,4cacia pulp made from the same process. Therefore, it couldbe concluded that P-RC APMP pulping properties of A. mangium is better than A. crassicarpaand A. cincinata.The study on contamination characteristics of effluents showed that COD load, BOD load, SSload and Chromaticity were prone to rise with the increase in the chemical charges. Under thesame condition, all the pollution charges of effluents from pulping process of A. cincinata woodwere highest, and the loads originating from A. mangium pulping were lowest besides its BODin proximity to that of A. crassicarpa and SS a little more than that of A. crassicarpa. Thus,from the point of environmental protection, A. mangium wood is more applicable to produceP-RC APMP pulp. |
