Isolation And Analysis Of Rice Straw Parenchyma Cells And The Study Of Their Film-forming Mechanism

Chinese paper industry has come in the first place with the largest production also consumption of paper products,but faces the dilemmas of high dependent on import of wood ray materials and frustrated development of straw pulping industry.In order to revitalize straw pulping industry,it is essential to eliminate silicone interference in alkali recovery of the black liquor,and remove parenchyma cells from straw pulp so as to improve its drainability greatly.Soda-oxygen pulping of straw can be said to an ideal way to reduce silicone content in the black liquor significantly,and what’s left of the work should focus on efficient separation of parenchyma cells from straw pulp and utilizing them well.It made the objective in this study.Mechanical screening,hierarchical sedimentation and overflow of fines from rice straw soda-oxygen pulp were individually attempted to separate the parenchyma cells in them.As a result,the highest proportion of parenchyma cells was obtained by the method hierarchical sedimentation.At the same time,it was found that microscopic observation was an intuitive,simple,and easy method to evaluate quantitatively the separation effect through counting parenchyma cells and fibrous cells.Based on the single factor experiments included in oven dry weight,dumping times,number of sedimentation,sedimentation time,volume of water taken and number of times water was taken,the latter four factors were optimized by response surface methodology in the separation process.The optimum conditions were volume of water taken 580 mL,number of times water was taken 24,sedimentation time 72 min,and number of sedimentation 4 times,when the minimum RFP was 9.70%.The morphology,specific surface area,and zeta potential of the separated parenchyma cells were characterized by means of SEM,BET,and Zeta potential.The results showed that they seem rectangular flake,rough surface,and their specific surface area(15.948 m2/g)were almost three times the fines,also had a zeta potential of-53.2 mV,being half of that of the fines.The membranes made from parenchymas were characterized by SEM,tensile strength,XRD,FTIR,and TG.It was found that the formed membranes had the compact combination of the parenchyma cells,and more evenly covered by them with the increase of the quantification,accordingly,resulting in significant increase of their tensile strength.The parenchyma cells treated by ultrasonic disperser with a power of 1000 W appeared more rough surface,more deformable tissue,and degressive crystallinity of the cellulose,with the increase of the dispersing time.The effect was to make the formed membranes more compact combination then fold increase of their strength,and better thermal stability.