Characterization And Role Of Oxygen Free Radicals In Bagasse Oxygen-alkali Pulping Process

With the rapid development of national economy and the great increase in the demand for paper products,shortage of raw materials has become one of the most important issue in the paper industry.Bagasse,sugar industry by-product,could be use for the raw material for pulping mill because of its fiber shape are similar to the hardwood.It is an effective way to impove the shortage of raw materials,reduce environmental pollution,increase local economic that bagasse is cooked by alkali-oxygen pulping method.This paper aimed to develop the degradation of carbohydrate in the process of alkali-oxygen cooking.Firstly,the chemical compositions,FT-IR,XRD,SEM,BET and pulping properties were analyzed.Then the pulp was treated by self-made oxygen free radical system and pulping selectivity of different stage pulp were investigated.At last,the effect of the radicals control agents on pulping properties were studied.The results of pulping selectivity in the process of alkali-oxygen cooking were shown as follows:there is a high effective stage of delignification and excellent selectivity pulping in the process of heating stage.The lignin and hemicellulose were dissolved impactful,the porosity and crystallinity of materials were increased and the fiber fasciculus was observed.The pulping selectivity is good in the early stage of max temperature,and the porosity and crystallinity of materials were increased futher and the fibers with a little of fasciculus was observed.The pulping selectivity is poor in the latter stage of max temperature,the pulped is bleached and the fibers with little of fasciculus was observed.The results of Characterization and delignification selectivity of oxygen free radicals were shown as follows:hydroxyl radicals were prepared by the alkaline Fenton reaction and the superoxide anion free radicals were prepared by atuo-oxidation of 1,2,3-trihydroxybenzene.The ability and selectivity of delignification were different when the pulp were treated by hydroxyl radicals or the superoxide anion free radicals.The delignification selectivity is excellent of the pulp before the max temperature by hydroxyl radicals treated,and the viscosity of treated pulp is similar to that of untreated pulp.While the delignification selectivity of the pulp from the max temperature stage were decreased.Compared with hydroxyl radicals treatment,the pulp from the latter stage of max temperature with better delignification selectivity when treated by superoxide anion free radicals.The results of the effect of the radical control agents on pulping properties were shown as follows:ascorbic acid is a good scavenging agent for hydroxyl radical and anthraquinone-2-sodium sulfonate is a good promoter for superoxide anion free radicals.The addition of agent is benefited for the alkali-oxygen pulping.To ascorbic acid,when it was added at the early stage of cooking about 0.3%,the pulping properties was improved obviously,The screened yield increased by 6.25%.While to anthraquinone-2-sodium sulfonate,when it was added at the middle stage of cooking about 0.2%,the pulping properties was better,The screened yield increased by 3.43%,kappa lower 2.4,increased by 4%ISO brightness.