低共熔溶剂预处理毛竹制备无醛木材胶黏剂和可发酵糖试验OA

In this study,bamboo was used as raw material and pretreated with a ternary deep eutectic solvent(DES)system consisting of choline chloride(ChCl),oxalic acid(OA),and 1,4-butanediol(BDO).This innovative pretreatment approach was designed not only to efficiently fractionate the main components of lignocellulose but also to preserve the native structural features of lignin.The objective was to achieve effective lignin separation while maintaining a low degree of polycondensation,thereby enhancing substrate accessibility and evaluating the feasibility of utilizing low-polycondensation lignin as an environmentally friendly plywood adhesive.The rationale behind selecting this specific ternary combination lies in the synergistic effects among the constituents:ChCl acts as an effective hydrogen bond acceptor,OA serves as an acidic catalyst for cleaving ether bonds,and BDO enhances solubility and mass transfer during pretreatment.After pretreatment,the obtained samples were subjected to the gel permeation chromatography(GPC),X-ray diffraction(XRD),and nuclear magnetic resonance(NMR)methods for comprehensive structural elucidation.These advanced analytical techniques were employed to explore the influence and interaction mechanism of the ternary DES on the structure of raw material.The results showed that the lignin removal rate could reach 66.9%under 110℃pretreatment for 4 h,and the cellulose and xylan recovery rates were maintained at 92.1%and 7.5%,respectively.Such high delignification efficiency alongside high carbohydrate retention underscores the selectivity of the solvent system.The glucose and xylose yielded after enzymatic hydrolysis could reach 100%,indicating significantly enhanced digestibility of the pretreated biomass.Structural analysis revealed that the aryl ether bond(β-O-4)content of the recovered lignin was as high as 32.6/100Ar,and the polycondensation reaction maintained as low as 19.54/100Ar.This high retention of native linkages is crucial for the subsequent adhesive application,as it improves the reactivity and binding capability of lignin.The dry and wet bonding strengths of the recovered lignin as a plywood adhesive reached 1.59 and 1.43 MPa,respectively,far exceeding the national standard.Moreover,the reusability of the DES system was evaluated to assess its economic and environmental feasibility.At the same time,DES can still maintain a lignin removal rate of more than 60%and a saccharification efficiency of 85.25%after being recycled 4 times.This demonstrates remarkable recyclability,reducing both operational costs and environmental impact.Therefore,this study presents a green and efficient pretreatment strategy for the high-value utilization of lignocellulose and establishes a technical foundation for the development of bio-based adhesives.The results underscore the potential of ternary DESs in biorefinery applications and pave the way for sustainable adhesive production from renewable resources.