(198a) Effect of Stirring Ball Milling on Structure and Hydrolysis of Camphorwood Sawdust
Mechanical activation can destroy the crystal structure of cellulose and promote its degradation. Camphorwood sawdust was mechanically activated with a stirring ball mill to study its change of structure and hydrolyzation catalyzed by CO2 in hot water. The effects of milling time, mass ratio of ball to biomass, ball grinding rotation speed on the crystal structure, particle size distribution, surface topography and hydrolysis of biomass were studied. The structural changes and particle size distribution of camphor wood chips were characterized by scanning electron- microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and laser granularity analyzer. The results show that stirring ball mill can remarkably reduce the particle size of camphorwood sawdust and make the crystal structure of sawdust cellulose destroyed at the ball grinding rotation speed 450rpm, milling time 2h and mass ratio of ball to biomass 30:1. The crystallinity declines from 60.9% to 21.4%. D50 decreases from 25.07μm decreased to 9.29μm,and the corresponding specific surface area increases from 1.79 m2 ·g-1 to 4.88 m2 ·g-1. After activation, hydrolysis was conducted at temperature of 180 °C, pressure of 8 MPa CO2 and reaction time of 60 minutes. Cellulose conversion reaches 37.75%, which is nearly four times of that of unactivated raw biomass. Reducing sugar content in hydrolysate was determined by the dinitrosalicylic acid (DNS) method. The concentration of reducing sugar content in the hydrolysate is 6.02 g/L after activation, which increases by 31.15% compared to unactivated raw material.