| As an abundant renewable resource,lignocellulosic biomass has become an ideal substitute for fossil resources.At the moment,the application of converting lignocellulosic biomass resources into a series of green energy,chemicals and biomass-based materials has received extensive attention with the improvement of biomass refining process.Therefore,to improve value-added utilization of lignocellulosic biomass resources,their main components are preferentially separated cleanly and efficiently,and their structures are further analyzed comprehensively and systematically.In this work,the lignocellulosic biomass feedstocks（perennial ryegrass,poplar and Chinese parasol）were used as the research object,and the separation and extraction of their hemicelluloses and lignin with high yield and high purity were carried out by combining various pretreatment methods,which improved enzymatic hydrolysis efficiency of cellulose from lignocellulosic biomass and enhanced the subsequent production of biofuel.Meanwhile,by the systematic analysis of the chemical structures of three main components and the comprehensive understanding of their structural properties,the biomass-based functional adsorption materials were prepared,which provided a certain reference for the value-added utilization of lignocellulosic biomass resources in the field of water environment treatment.Aiming at the investigation of the perennial ryegrass feedstock,a comprehensive treatment process of ultrasonic-hydrothermal pretreatments and dilute alkali continuous extraction was put forward,and the yields,chemical compositions and structural transformations of hemicelluloses and the influences of the enzymatic hydrolysis efficiency of cellulose were elucidated in the comprehensive treatment process.It was known that more than 90%of the original hemicelluloses in the cell wall of ryegrass could be released by this comprehensive treatment process,and the obtained hemicelluloses mainly contained?-arabino-（4-O-methyl-?-glucurono）xylans,galactoarabinoxylans,andβ-glucans.In addition,the effective removal of amorphous hemicelluloses and lignin significantly increased the enzymatic hydrolysis efficiency of ryegrass cellulose from 43.8%to 91.1%.These results provide novel insights into the subsequent synergistic utilization of hemicelluloses and cellulose in ryegrass.To reveal the structural characteristics and physicochemical properties of perennial ryegrass lignin,a combined technology of ultrasonic-hydrothermal pretreatment coupled with dilute alkali continuous treatment/enzymatic hydrolysis was proposed.It was found that the total yield of alkali-soluble lignin obtained by ultrasonic-hydrothermal pretreatment coupled with diluted alkali continuous treatment was 13.5%,accounting for 89.4%of the original lignin release from ryegrass cell wall,compared with the double enzymatic lignin prepared by ultrasonic-hydrothermal pretreatment coupled with enzymatic hydrolysis（14.5%and 96.0%）.In addition,two kinds of lignins obtained were S-,G-,and H-type lignins,and contained different amounts of p-coumarates and ferulates.Meanwhile,except for the abundantβ-O-4 aryl ether bonds,there are also a small number ofβ-β,β-5 andβ-1 carbon-carbon bonds between the structural units of lignins.An integrated treatment method of microwave-assisted hydrothermal pretreatment（MW-HTP）and dilute alkali treatment was employed for the clean and efficient separation of lignin from poplar and revealing its structural characteristics.It was found that the yields of lignin obtained by the integrated treatment based on MW-HTP process were significantly increased to 52.6%,and their associated sugars contents were clearly decreased to 0.19-0.09%,as compared with the yield of lignin extracted without microwave treatment and its associated sugar content（29.8%and 0.29%）.At the same time,the integrated treatment based on MW-HTP process promoted the cleavage ofβ-O-4 aryl ether bonds in lignin macromolecules of poplar wood,resulting in the increase of their total phenolic hydroxyl contents from 1.87 mmol g-1 to 2.36 mmol g-1.Most importantly,it is known from various characterizations that the fractionated lignin was mainly S-and G-type lignins,as well as the structural units were mainly composed ofβ-O-4 aryl ether bonds and a certain amount ofβ-βandβ-5 carbon-carbon bonds.Generally,the completion of this work will provide useful information on the efficient utilization of lignin macromolecules during biomass refining.Considering the value-added utilization of lignocellulosic biomass resources,a neoteric wood-derived adsorbent material（WBP-COOH）was prepared by targeted delignification and subsequent chemical modification of Chinese sycamore wood,as well as its application was expanded in the field of water pollution treatment.It was found that the carboxyl groups were successfully introduced into the prepared WBP-COOH adsorbent after delignification and subsequent chemical modification,which increased the active sites for the adsorption of heavy metal ions.According to the analyses of adsorption isotherm and kinetic models,the adsorption process of Pb（II）ions by WBP-COOH adsorbent belonged to monolayer chemisorption,and its maximum adsorption capacity was 280.98 mg g-1.Additionally,due to its excellent stability and regeneration performance,the WBP-COOH adsorbent could not only effectively remove heavy metal ions in wastewater,but also react chemiluminescence in the reaction system of luminol reagent and hydrogen peroxide after the adsorption of heavy metal ions.In conclusion,the preparation of wood-derived adsorption materials with efficient adsorption performance for heavy metal ions and chemiluminescence after adsorption,which provides broad prospects and ideas for the development and value-added utilization of lignocellulosic biomass resources in the future. |
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