Study On Pretreatment Technologies And Properties Of Moso Bamboo Dissolving Pulp

Dissolving pulp, one kind of chemical pulp that composed of high purity and qualitycellulose, is mainly applied to the preparation of regenerated cellulose fiber. Now, seriesproblems, like shortage of resources, serious pollution of environment and the great fluctuationof market price, are stunting the development of dissolving pulp industry. Fortunately, China islocated in the center of the world bamboo distribution region. And the level of bamboo species,area, accumulation, and output are all the highest in the world. China is usually called ofBamboo Kingdom. Moreover, moso bamboo takes up about70percentage of bamboo resourcearea in our country. So researching on the pretreatment technologies of dissolving pulp by usingmoso bamboo can not only relieve resource scarcity and reduce environment stress, but alsopromote the development of bamboo industry.In this paper, a kind of five years old moso bamboo, which came from Zhejiang anji, wasused to prepare dissolving pulp. Meanwhile, study on pretreatment technologies and propertiesof moso bamboo dissolving pulp.1. Explore the prehydrolysis rules of moso dissolving pulp.Firstly, in order to research the effect of each chemical composition that dissolved out fromthe raw material of moso bamboo, the main chemical compositions of moso bamboo should beanalyzed. The results shown that cellulose content was45.354%, pentosan content was21.942%,ash content was1.057%, Klason lignin content was22.918%, hot-water extractive content was6.052%,1%NaOH extractive content was26.692%, and benzene-alcohol extractive content was7.096%.Secondly, prehydrolysis experiments were carried out to discuss the effect of temperatureand time of water prehydrolysis on yield, pH of wasted liquid, and each composition’s retentionrate. Under the premise of keeping cellulose as much as possible, optimized the waterprehydrolysis process. The optimal conditions of moso bamboo were as followed: liquor ratio 1:8, holding temperature150℃, holding time120min, as a result, the prehydrolysis product withyield of90.35%, wasted liquid pH of3.85, cellulose content of48.33%, pentosan content of20.45%, Klason lignin content of22.36%, ash content of0.137%and with each composition’sretention rate as follows: cellulose retention rate was96.30%, pentosan retention rate was88.22%, ash retention rate was11.71%, Klason lignin retention rate was88.13%.2. Study on kraft pulping process for moso dissolving pulp’s preparation.By conducting the orthogonal experiments and single factor supplementary experiments, theoptimal conditions for kraft pulping process were obtained as follows: holding temperature155℃, holding time60min, alkali charge18%,sulfidity25%, liquor ratio1:4, heating rate4℃-5℃/10min, initial temperature90℃. As a result, themoso pulp with yield of31.36%,α-cellulose content of93.33%, kappa number of21.07, black liquor pH of12.33, cellulosecontent of92.98%, pentosan content of8.12%, Klason lignin content of1.37%, and averagedegree of polymerization of935was obtained.3. Study on properties and features of moso bamboo, the bamboo chips after prehydrolysisprocess and bamboo pulp.After prehydrolysis process, SEM results revealed that moso bamboo structure turnedloosely. And XRD analysis shown that the degree of crystallinity was increased from52.7%to64%. However, FTIR haven’t changed obviously. Analysis above revealed that part ofhemicellulose and lignin were dissolving out, which created a favorable environment for cookingliquor to penetrate.After kraft pulping process, SEM results shown that moso bamboo were completelyseparated into single fibers. Seen from FTIR, a lot of characteristic peaks which belong tohemicellulose and lignin disappeared. And the degree of crystallinity was substantially increased.The results shown that after the process of kraft pulping, most of hemicellulose and lignin wereremoved.