The Extraction,Characterization And Degradation Of Lignin From Shells Of Quercus Variabilis BL

The study on acorn shell of Quercus variabilis was present.The chemical composition of acorn shell was measured.And then,Ethanol lignin（EL）,alkali lignin（AL）,milled wood lignin（MWL）and cellulase enzymatic lignin（CEL）were extracted from acorn shell ofQuercus variabilis Bl.,the extraction processes of AL were optimized by using the response surface method（RSM）.And then,the lignin preparations were studied by GPC,TG,SEM,FT-IR,¹³C-NMR,DEPT-135 NMR,2D-HSQC and functional groups measurement.Then the degradation of AL and MWL was taken out,the degradation product was analyzed by using FTIR,GC-MS,HPLC and SEM.The results were as follow:（1）The content of lignin in acorn shell of Quercus variabilis was 24.59%.（2）the extraction processes of AL were optimized by using RSM,optimized conditions were temperature of 64°C,time of 4.2 h,alkaline concentration of 0.8 mol/L and liquid-solid ratio of 25.The yields of the lignins preparation were 13.21±0.41%（EL）,16.63±0.30%（AL,optimized conditions）,13.17±0.12%（MWL）and 11.20±0.15%（CEL）.The yields were far away from the lignin content of shell.（3）The four lignin preparations exhibited analogous molecular weight distributions and polydispersity,CEL had a broader molecular weight distribution;it was proved the existence of a less thermally stable domain within the lignin polymer,The CEL was little more stable than others.（4）The isolation conditions of lignin samples had significant effects on the microstructures of the lignin samples.The appearance of lignin was round shaped.The aggregation dimension of CEL had a tendency to increase;four lignin preparations were all amorphous polymer;various functional groups and structural fragments in the lignin were characterized by FT-IR analysis;The contents of active groups of MWL and CEL were lower than those of AL and EL.（5）Proton and carbon chain structure and lignin fragments were analyzed by using ¹H-NMR,¹³C-NMR and DEPT-135-NMR;informations of lignin fragments and linkage were analyzed by using 2D HSQC,the relative content ofβ-O-4’linkage in MWLwas lower than that in EL,AL and CEL,AL had a higher S/G ratio than EL,MWL and CEL.（6）The alkaline peroxide treatment did not affect the benzene ring structure of lignin except for the increases of carboxyl and carbonyl groups in the lignin;the surface of lignin preparations were more“structured”and stable after degradation.（7）There were lots of aromatic aldehyde and ketone,and some aromatic acid and phenolics in bio-oil of degradation MWL;the contents of vanillic acid,syringaldehyde and acetosyringone in degradation MWL were higher than that in AL,when the content of p-hydroxybenzonic acid was rather lower;copper oxide and manganese oxide were provided to be good catalysts in the alkaline peroxide degradation of MWL.