Soda-CT-1 Additive Pulping And TCF Bleaching Of Bagasse With Black Liquor Pretreatment

Bagasse is an important kind of non-timber fiber material for pulping and paper making . Pulping and TCF bleaching of Bagasse were studied in this thesis in following respects: (1) Soda-CT-1 additive pulping of bagasse with black liquor pretreatment. (2) The technological process of OP and OOP bleaching. (3) Synthesis of p-acetoxybenzensulfonate sodium and its application in TCF bleaching. The main conclusions are as the follows.Improved alkaline cooking with black liquor pretreatment as the first stage has better delignification selectivity and rate than conventional alkaline cooking. And the pulp from the former has high yield , viscosity , brightness and lower potassium permanganate number than from the latter obviously.The optimal technical parameters in the first stage cooking are as follows : cooking temperature 115℃, time to cooking temperature 45min , additive CT-1 dosage 0.06%. And in the second stage are : max temperature 153℃, alkaline charge 14.5%, retention time 30min . the properties of the bagasses pulp from this cooking are : yield 59.64% , KMnO4 number 9.00, brightness 42.6%ISO, viscosity 1099ml/g.two-stage oxygen delignification of bagasse alkaline cooking pulp with black liquor pretreatment could reach 75% delignification rate, pulp of which has better properties. The optimal technical parameters are: temperature 100℃ and NaOH charge 1.8% in the first stage; temperature 115℃ and NaOH charge 1.2% in the second stage, oxygen pressure 0.8 MPa , retention time 40min , time to temperature 40min in the oxygen delignification stage. One-stage oxygen delignification could reach 70% delignification rate by strengthening technical conditions, the viscosity of the pulp is little lower but could be accepted . Theoptimal technical parameters are: oxygen pressure 0.8 MPa , temperature 115, NaOH charge 3%, retention time 40min ,time to temperature 40min.OP and OOP are two feasible TCF sequent to bleach bagasse pulp to high brightness. H2O2 bleaching of one-stage-oxygen-delignification bagasse pulp could reach 81.2% ISO brightness and 781ml/g viscosity under the condition of bleaching temperature 86 , time 150min, H2O2 dosage 1.0%. however, H2O2 bleaching of two-stage-oxygen-delignification bagasse pulp could gain 83.9%ISO brightness under the same bleaching condition. When H2O2 dosage increased to 1.2% ,the bleached pulp with 84.3%ISO brightness and 736ml/g viscosity could be obtained.P-acetoxybenzenesulfonate sodium is an effective activator in H2O2-bleaching. The bleached pulp has a higher brightness at a lower bleaching temperature and shorter reaction time compared with the conventional H2O2 bleaching process when it is added in H2O2-bleaching of bagasse pulp. The addition method of activator has important influence on bleached pulp brightness. It should be added by several batch when demanded much activator charge.P-acetoxybenzensulfonate sodium was also synthesized using 4-phenolsulfonate sodium and acetic anhydride in the presence of pyridine and water as solvent, which yield reached 71%. The structure of p-acetoxybenzensulfonate was characterized by FT-IR spectra analysis, which showed the product was p-acetoxybenzensulfonate . The suitable synthesis conditions are: reaction temperature 30 ℃ , time 2.5h, molar ratio of 4-phenolsulfonate sodium to acetic anhydride 0.5.FT-IR spectra analysis shows that aromatic ring vibration gradually decreased ,comparing activated bleaching with the conventional method .The fragmentation ofresidual lignin and conversion of chromophoric groups were most mechanism ofactivated bleaching .