The Preparation And Application Research Of Cellulose Nanocrystals

In this study, CNCs were prepared from corncob cellulose hydrolyzed by ammonium persulfate. Then D-limonene Pickering emulsions and β-carotene were successful prepared by sonicating D-limonene(β-carotene)and CNCs aqueous dispersion, Furthermore, effects of different environmental factors on the stability of Pickering emulsion were analyzed in detail.CNCs were prepared by ammonium persulfate hydrolysis of corncob cellulose. The effects of different reaction conditions on CNCs yield were then investigated:reacting time, the input amount of corncob, different concentrations of APS and reacting temperate. As indicated by the experiment data, when the starting biomass material (1g) was added to100mL of1M ammonium persulfate solution and the mixture was heated to60℃for16h, the yield of CNCs was68%.And then the carboxyl content of CNCs was then determination.Then CNCs were investigated by Fourier transform infrared (FTIR) spectroscopy, X ray diffraction (XRD), thermogravimetric analysis (TGA). The dimensions of CNCs were investigated by Malvern dynamic light scattering.D-limonene Pickering emulsions were generated by ultrasonic (high shear method or high pressure homogenization method) method, and then stability of emulsion prepared by three methods was compared. The morphology and size of the prepared emulsions were studied by optical microscopy and laser light diffraction. In addition, factors that may affect the stability of emulsions such as ionic concentration, pH and temperature were also studied. As indicated by the experiment data, stability of emulsions prepared by high shear method was worst, stability of emulsions prepared by high homogenization method was the best, but more starting materials were needed by this method. Stability of D-limonene Pickering emulsions prepared by ultrasonic method were better, and little starting materials were needed. As indicated by the experiment data of stability, when temperature rose, the stability of emulsions would be increased, and the stability of emulsions was reduced with low pH or high salt concentration due to electrostatic screening of the negatively charged CNC particles. Adding planet oil in the oil phase can improve the stability of the emulsion.P-carotene Pickering emulsions were generated by ultrasonic method. The effects of different reaction conditions on stability of β-carotene were then investigated:ultrasonic time, ultrasonic power, temperature, pH, illumination time, ionic concentration, oxidizing agent and antioxidant. As indicated by the experiment data, when ultrasonic time increased, the stability of (3-carotene would be increased. When ultrasonic power increased, the stability of β-carotene would be increased during0.1kW to0.6kW, and then decreased when ultrasonic power was0.7kW. When temperature rose, the stability of emulsions would be decreased. Addition of EDTA-2Na did not increased the stability of β-carotene. It revealed that hydrogen peroxide induced (3-carotene degradation, and the stability of emulsions would be decreased. And β-carotene was degraded with salt concentration increasing. So β-carotene should be stored in shade and closed environment.