Study On The Oxygen-alkali Pulping Properties Of Bagasse With Wet Stockpiling Pretreatmen

With the rapid development of paper industry,environmental issue and shortage of raw material increasingly have become serious.Eco-friendly oxygen-alkali pulping technology combined with wetstorage pretreatment and non-wood fiber was used as raw material,which was beneficial to alleviate the pressure of the shortage of raw material and environmental issue.In this paper,agricultural solid waste-bagasse was used as raw material,the effect of wetstorage pretreatment on the properties of bagasse,waste liquid and oxygen-alkali pulping was studied.Then the wetstorage of oxygen-alkali pulping was optimized.Morever,the related mechanism on oxygen-alkali pulping with wetstorage pretreatment was studied by XRD,XPS and IR.The results showed that microorganism can use bagasse itself and substances dissolved from bagasseas as nutrients,without additional nutrients in the process of bagasse wetstorage.During the process of wetstorage carbohydrates and degraded lignin were dissolved into storage waste liquid from bagasse.According to the properties of raw materials,pulping and paper strength,the optimal conditions of wetstorage pretreatment was pH of 6.0 for 16 days.After bagasse was treated under the optimized conditions,the chemical compositions of bagasse were as followed:pentosan content is 18.12%,cellulose content is 49.62%,holocellulose content is 76.09%,Klason lignin content is 20.48%,acid soluble lignin content is 1.41%,content of benzene-alcohol extractive is 1.10%;Compared with the control sample,contents of acid soluble lignin and benzene-alcohol extractive were reduced.Then the bagasse was cooked under the conditions:alkali charge was 23%,oxygen pressure was 0.6 MPa,MgSO4 dosage was 0.5%,pulp concentration was 12%,the highest temperature was 100℃,time at highest tempreture was 180 min,the properties of pulp were as followed:unscreened pulp yield was 60.00%,the kappa value was 14.1,viscosity was 704 mL/g,whiteness was 50.43%ISO,content of residual alkali was 2.48 g/L.Compared with control sample,pulp yield was increased by 2.93%,the viscosity was improved by 100 mL/g,the residual alkali content of pulping was also improved,while kappa value the pulp was increased by 0.9,whiteness was declined by 6.77%ISO.The properties of oxygen-alkali pulp were as followed:tensile index was 54.62 N·m/g,tear index was 4.32 mN·m2/g,burst index was 2.53 kPa·m2/g,folding degrees was 45 times;Compared with the control sample,tensile index was increased by 1.92 N·m/g,tear index was increased by 0.33 mN·m2/g,burst index was increased by 0.05 kPa·m2/g.The mechanism of bagasse oxygen-alkali pulping with wetstorage pretreatment showed that the wetstorage pretreatment before pulping was beneficial to the dissolution of small molecule lignin and sugar from bagasse.And it made the material structure more loose,which was beneficial to the improvement of the crystallinity of cellulose and enhancement of the delignification selectivity of subsequent pulping process.