| Dissolving pulp is a high-quality pulp product with very high cellulose content?>90%?,low hemicellulose content?<4%?,very little ash and extracts,which can be used to produce viscose rayon,acetate,nitrocellulose,and nanocellulose materials.Nanopaper is self-assembled by removing the solvent from nanocellulose by drying,etc.It can be widely used in many fields such as flexible electronic devices,supercapacitor electrodes,packaging barrier materials.In this paper,the biomass conversion concept of biomass refining is used to prepare the dissolving pulp from the common grass plant Eulaliopsis binata,in southwestern China.First,the first step of pretreatment is to treat the Eulaliopsis binata by pre-hydrolysis of dilute sulfuric acid.By optimizing the reaction time and reaction temperature of the pretreatment,the hemicellulose removal rate is 89.5%when treated at 160°C and 0.2 wt%dilute sulfuric acid.The yield of the pigment was 70.4%,and the content of the remaining hemicellulose was about 4%.The morphology,structure and composition of Eulaliopsis binata were analyzed by IR,XRD,SEM and elemental analysis.The concentration of xylose in the dilute sulfuric acid pretreatment sugar solution was 21.84 g/L;the content of inhibitors such as phenols and furfural was about0.79 g/L;after detoxification by Sigma laccase,70%of the phenols were removed;After electrodialysis purification,most of the inhibitors such as furfural are removed;and the high concentration of xylose sugar liquid is obtained by membrane concentration technology;the total conversion rate of the sugar liquid by hydrogenation catalytic conversion is as high as 63.7%,which is purer than related literature.The conversion of diol is 14%higher than glucose.The second step of pretreatment was carried out by ammonium sulfite?AS?treatment and KOH treatment,and the experimental conditions were optimized to obtain a?liquid-solid ratio was 8?of 30 wt%AS at a?liquid-solid ratio was 6?of 160°C for 2.5h,and then a of 6 wt%KOH at 140°C.Under the condition for 2h,the total removal rate of lignin can reach 91.7%,and the residual lignin content is less than 5%.The solid and black liquors were characterized by IR,XRD,SEM,SEM-EDS and elemental analysis.The results showed that the black liquor after ammonium sulfite and KOH treatment contained a large amount of C,O,N,S,K and other elements,and almost no heavy metal salt ions such as Cr,Hg,Pb,fully prove that the lignin black liquor after AS and KOH treatment can produce nitrogen and potassium fertilizer through subsequent oxidative ammoniation.In the third step of pretreatment,the asparagus fiber was further purified by bleaching and refining.After optimization of the bleaching process,the content of cellulose in the obtained dissolving pulp was 92.2%,the degree of polymerization was544,and the reactivity was 53.8%,which was consistent with the quality of the viscose produced by the dissolving pulp.And exhibits higher reactivity than the market common commercial pulp.The morphology and structure of the dissolving pulp were analyzed by IR,XRD,SEM,elemental analysis,etc.The crystallinity of the dissolving pulp was as high as 76.7%,which is the highest value of the crystallinity of Eulaliopsis binata in the existing literature.Both dissolving pulp and unbleached fibers can be used to prepare nanocellulose.Nanocellulose?CNF?with different lignin content can be prepared by formic acid hydrolysis combined with high pressure homogenization method,and then dried by suction filtration.Cellulose nanopaper was obtained.The particle size distribution,thermal stability and mechanical properties of CNF and nanopaper were tested by TEM,TG and tensile test.It was found that nanopaper has high thermal stability and superior mechanical properties(tensile strength and the toughness is 254.8 MPa and 19.5 MJm-3,respectively,which is much higher than ordinary nano paper),and has potential application value in the field of membrane water treatment technology.In this paper,the concept of biomass refining adopts the cheap,clean and efficient three-step process for the pulping process of Eulaliopsis binata.It not only produces highly reactive dissolving pulp,but also lignin organic fertilizer and high added value.The diol product,and the dissolving pulp and Eulaliopsis binata fiber can further prepare nanocellulose and nanopaper with excellent performance,thereby establishing a medium-pilot process platform for comprehensive utilization of various components of Eulaliopsis binata,for realizing biomass three Separation and comprehensive utilization provide a new approach. |
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