Study on cellulose degradation induced by hydroxyl radical with cellobiose as a model using GC-MS, ReaxFF simulation and DFT computation

The (OH)-O-center dot induced cellulose degradation was examined by analyzing the reaction products of Fenton's regents with cellobiose. Many degradation products including C2-C5 compounds such as oxaldehyde, malonaldehyde and 2-hydroxysuccinaldehyde were detected by GC-MS analysis. Four reaction pathways for the formation of some degradation products were obtained from ReaxFF kinetics simulation and validated by the DFT quantum chemistry calculation at B3LYP/6-31+g(d,p) level. It was found that the H-abstraction from OH of the glucose unit by (OH)-O-center dot can cause saccharide ring open and breakage of the glycosidic bond. Pathways 1-4 showed that the glucose unit can react with (OH)-O-center dot consecutively to produce small molecular products with carbon atoms less than 6. This study indicated that ReaxFF reaction kinetics is a powerful tool for the exploration of the degradation mechanism of cellulose induced by (OH)-O-center dot at room temperature, which correlated well with the experimental results and was validated by DFT calculation.