Optimization of Ultrasonic Assisted Alkaline Hydrogen Peroxide Extraction and Structural Characterization of Cellulose from Young Fruit of Guanxi Honey Pomelo

The extraction of cellulose from the young fruit of Guanxi honey pomelo was studied by ultrasonic assisted alkaline hydrogen peroxide method. On the basis of single factor experiments, taking the cellulose purity as the index, the combination experiment of Design-Expert 8.0 design center was used to optimize the extraction process of cellulose by response surface analysis, the cellulose was analyzed by IR and SEM. The results showed that the change of ultrasonic power had no significant effect on the purity and yield of cellulose, but water bath temperature, ultrasonic time, volume fraction of hydrogen peroxide solution and mass concentration of sodium hydroxide solution had significant effects on the purity and yield of cellulose. The optimum extraction conditions were as follows: Ultrasonic power 200 W, ultrasonic time 40 min, water bath temperature 80 ℃, H₂O₂ volume fraction 0.9%, NaOH mass concentration 9%. Under these conditions, the predicted value of cellulose purity was 88.48%, and the measured value was 88.95%, under this condition, the yield of cellulose was 17.65%. Infrared analysis showed that cellulose was successfully prepared. SEM analysis showed that the surface structure of cellulose was looser and the gully was deeper than that of Guanxi honey pomelo young fruit before treatment. X-ray diffraction analysis showed that cellulose had type I structure and the crystallinity was 44.26%. This experiment optimized the ultrasonic assisted alkaline hydrogen peroxide extraction process of cellulose from young fruits of Guanxi honey pomelo. It was an efficient and easy to popularize cellulose preparation method, which would provide a reference for the utilization of young fruits of Guanxi honey pomelo and the development of cellulose.