玉米芯木质素的低共熔溶剂解聚、表征及分子模拟OA

Corncob lignin was used as raw material to investigate the effects of depolymerization parameters such as solvent system,treatment method and time on the yield and relative molecular mass of lignin oligomer.The obtained depolymerized lignin was characterized and quantitatively analyzed by Fourier transform infrared spectroscopy,and nuclear magnetic resonance hydrogen spectroscopy.Molecular dynamics simulation was employed to elucidate the role of deep eutectic solvent(DES)in lignin depolymerization,and to explore the universality of this method for lignin from different sources.The results showed that the optimal depolymerization effect was achieved by using a choline chloride-lactic acid solvent system combined with ultrasonic-assisted treatment for3 h at room temperature(25℃water bath).At this time,the yield of lignin oligomer reached 73.50%,the weight-average relative molecular mass decreased significantly from the initial 6 091 to 1 663,and the polydispersity index decreased from 4.12 to 1.97.The depolymerization process well retained the fundamental structural units and main functional groups of lignin molecules,and the hydroxyl content increased by 72%.Molecular dynamics simulations clarified the effect of hydrogen bond donors and acceptors in DES on promoting lignin depolymerization.At the same time,DES exhibited excellent depolymerization effect on lignin of various raw materials under ultrasonic assistance.