تاثیر اولتراسوند و تخلیه الکتریکی ولتاژ بالا بر خواص فیزیکی و شیمیایی لیگنین و پالپ چغندر قند کیک آفتابگردان

Delignification was improved by both physical pretreatments. US increased the extractability of hemicelluloses and HVED induced a partial degradation of cellulose. Best synergies were observed for HVED-soda and US-organosolv treatments. The obtained lignin fractions were characterized with 13C NMR and 2D 1H–13C HSQC. It was observed that the physical treatments affected the syringyl/guaiacyl (S/G) ratios. The values of S/G were ≈1.19, 1.31 and 1.75 for organosolv, HVED-organosolv and US-organosolv processes, suggesting recondensation reactions. The lignin fractions obtained from HVED-organosolv treatment contained less quantity of p-coumaric acid and ferulic acid as compared to those extracted by US-organosolv. Thermogravimetric analysis (TGA) revealed a better heat resistance of physically extracted lignins as compared to the control. The enzymatic digestibility increased by 24.92% when applying HVED to mild organosolv treatment.