Study On Upgrading Of Bamboo Paper-grade Pulp To Dissolving Pulp

As one of the widely used natural polymers, cellulose has a universal application in theChemical industry, Food industry, Pharmaceutical industry and other applications. Recently,due to the rapid development of economy, industrial production has consumed a lot of oilresources, leading to an increasing shortage situation. Therefore, as a new source of bioenergy,the market demand for biomass cellulose is becoming larger and larger. Meanwhile, sinceChina has the most abundant bamboo resources, the research is heated in the area of usingbamboo fiber to make the biomass cellulose.The focus of this study was to use bamboo paper-grade pulp to make the dissolving pulpby alkali extraction and enzyme treatment. It included analyzing the main chemicalcomponents of the paper-pulp and dissolving pulp, finding the optimum process conditions ofalkali extraction process, exploring the method of improving the reactivity of the cellulose byenzyme treatment, and studying the process and mechanism of enzyme treatment.With regard to the comparison of main chemical components between paper-pulp anddissolving pulp, eucalyptus paper making pulp, bamboo paper making pulp, eucalyptusdissolving pulp and bamboo dissolving pulp were used in this study. The basicphysic-chemical properties of the fibers were analyzed and the structure was characterized byFTIR and WAXD. Compared with paper making pulp, the dissolving pulp contained more α—cellulose (up to95%) while had a lower viscosity, ash, organic extract and alkali solubility.The results of the FITR showed that the differences of FITR crystallite between paper makingpulp and dissolving pulp. The main cause was the structural changes of hydrogen bond due todifferent pulping processes which changed the fiber morphology. The results of WAXDrevealed that the crystallite and crystal size of dissolving pulps were much higher than that ofpaper-making pulps.Paper-grade pulp of bamboo was extracted by NaOH in order to produce cellulose. Theextraction conditions were optimized by using an orthogonal experiment design. The effectsof alkaline concentration, extraction time and temperature, liquor to pulp ration on the extraction yield, pulp pentosan content, pulp viscosity and the solubility of pulp in10%and18%NaOH were investigated. The experiment results showed that the optimum parameterswere as followed: liquor to pulp ration8:1, temperature60℃, extraction time90min andalkaline concentration10%. These conditions allowed82.85%of pentosan present in thepaper-grade pulp of bamboo to be extracted. The pulp properties under these optimumconditions were as followed: α-cellulosecontent of98.92%, the viscosity of8.8mpa.s,pentosan content of3.33%,92.30%ISO of whiteness, the ash content of0.11%,the extractionof0.06%.The experimental results showed that the optimum parameters of enzyme treatmentprocess were as followed: enzyme dosage500UI/g, pH8.0, the pulp concentration of4.0%,the reaction time of120min. The pulp properties under these optimum conditions were asfollowed: the reactivity increased to75.8%, the viscosity decreased to7.55mPa.s. Thebamboo dissolving pulp with high whiteness, high alpha cellulose content, low viscosity andhigh reactivity could be made by the method of enzyme treatment.