The Comparative Research Of Reed Pulp Of Kraft And Ethanol After Prehydrolysis

The comparison of the effects of ethanol and kraft pulping after reed prehydrolysis was studied in this paper. The emphasises were the dissolution of the process of pre-hydrolysis of lignin and hemicellulose, the effect on the follow-up pulping by prehydrolysis, and the feasibility of dissolving pulp by ethanol and sulfate cooking.The results indicated that with the improvement of the maximum temperature, the pentosan, lignin and ash content of reed piece were constantly reducing in hot water pretreatment process. The pretreatment has greatest impact on pentosan of the reed piece, followed by acid-soluble lignin and ash. With the temperature of prehydrolysis increased, the yield of the half-stuff and the pH value of the pre-hydrolyzate significantly decreased. The effect of the maximum temperature on the pentosan, lignin, ash content, cellulose content, and yields of the semi material pulp as well as the value of pH of the pre-hydrolyzate was far greater than the holding time.The optimal conditions of this prehydrolysis experiment were as follows:liquid ratio1:8, maximum temperature170℃, heating time30min, holding time105min.76.4%of hemicellulose,20.3%of cellulose,42.1%of lignin and75.1%of ash can be dissolved out by hydrolysis treatment under the conditions. The reeds kraft and ethanol pulping were conducted after treatment in the best prehydrolysis conditions. The effect of the cooking temperature and holding time on the pulp properties were investigated, and ultimately got the best cooking conditions. The best cooking conditions of the kraft pulping experiment were as follows:cooking temperature150℃, holding time60min, liquid ratio1:6(alkali amount20%, sulfidity25%).In this cooking conditions, the unbleached pulp of the kraft pulping after prehydrolysis obtained91.91%of a-cellulose content,0.67%of ash content. Compared to the raw materials, the content of acid insoluble lignin removed in addition to84.57%. Under this cooking condition, the performance of the pulp was in line with dissolving pulp standard indicators. At the condition of maximum temperature190℃, insulation3h, liquid ratio1:8 and50%ethanol concentration, the unbleached pulp obtained by the ethanol cooking prepared a-cellulose content of80.07%, ash content of1.47%, gravimetric rate of29.13%and compared to the raw materials, acid insoluble lignin content off in addition to84.57%.Compared the properties of the reed pulp of kraft and ethanol after prehydrolysis through the comparison of data and observing by scanning electron microscopy (SEM), results showed that the a-cellulose content of the slurry obtained by ethanol pulping was lower and lignin content was high, and the ash content was higher than the standard indicators of dissolving pulp. In future studies, it may try to improve the performance of the slurry through the ethanol alkaline pulping. An acid treatment stage can be added in conventional bleaching process, reducing the ash content of the slurry.