γ射线、电子束辐照处理对芦苇木质纤维素结构及酶解性能的影响

Effects ofγ-Ray and Electron Beam Irradiation Pretreatment on Structure and Enzymatic Efficiency of Lighocellulose in Phragmites australis

为更全面了解射线辐照对木质纤维素的影响,本试验利用扫描电子显微镜(SEM)、傅立叶红外光谱(FT-IR)、X射线衍射(XRD)、高效液相色谱(HPLC)等方法分析了γ射线和电子束辐照前后芦苇木质纤维素结构及酶解性能的变化。结果表明,γ射线和电子束辐照均能使芦苇木质纤维素发生降解,使部分纤维素、半纤维素降解为水溶性物质,且降解水平与吸收剂量呈正相关关系,当吸收剂量为500 kGy时,经γ射线和电子束辐照的芦苇水溶性组分含量分别是未辐照芦苇的2.44和1.98倍;γ射线和电子束辐照后芦苇的微观结构被破坏,芦苇木质纤维素体系中的分子数量增加,纤维素结晶指数降低,但纤维素晶型不改变;随着吸收剂量从200 kGy增加至500 kGy,芦苇纤维素、半纤维素酶解转化率逐渐提高,当吸收剂量为500 kGy时,γ射线和电子束辐照的芦苇纤维素酶解转化率分别为16.68%和18.84%,分别是未处理芦苇的2.32和2.62倍,芦苇半纤维素转化率分别为21.38%和21.74%,分别是未处理芦苇的3.82和3.88倍;同等吸收剂量的γ射线和电子束辐照对芦苇木质纤维素主要化学组分、物理化学结构的影响相似,在200~400 kGy剂量范围内,同等吸收剂量γ射线和电子束辐照对芦苇纤维素、半纤维素酶解转化的促进作用没有明显差异,当吸收剂量为500 kGy时,电子束辐照对芦苇纤维素酶解的促进作用显著优于γ射线。本研究为辐照技术应用于木质纤维素预处理提供了理论依据。

In order to understand the effects of radiation irradiation on lignocelluloses more comprehensively,the structure and enzymatic properties of Phragmites australis lignocelluloses(PAL)treated withγirradiation and electron beam were analyzed by SEM,FT-IR,XRD and HPLC.The results showed that bothγirradiation and electron beam could degrade PAL,in which some cellulose and hemicellulose were decomposed to watersoluble substances after irradiation,and the degradation level was positively correlated with the absorbed dose.When the absorbed dose was 500 kGy,the soluble fraction of PAL irradiated byγirradiation and electron beam were 2.44 and 1.98 times that of the control respectively.The microstructure of PAL was disrupted afterγirradiation and electron beam irradiation,the number of molecules in the PAL increased,and the cellulose crystalline index decreased,while the allomorph of cellulose remained unchanged.As the absorbed dose increased from 200 kGy to 500 kGy,the enzymatic conversion of cellulose and hemicellulose gradually increased.When the absorbed dose was 500 kGy,the enzymatic hydrolysis conversion rates of cellulose irradiated byγray and electron beam were 16.68%and 18.84%respectively,which were 2.32 and 2.62 times that of untreated PAL,and the hemicellulose conversion rates were 21.38%and 21.74%respectively,which were 3.82 and 3.88 times that of untreated PAL.The effects of equal absorbed dose ofγirradiation and electron beam irradiation on the main chemical components and physicochemical structure of PAL were similar.In the dose range of 200~400 kGy,there was no significant difference betweenγirradiation and electron beam in promoting the enzymatic efficiency of celluloseand hemicellulose,while when the absorbed dose was 500 kGy,the effect of electron beam irradiation on the enzymatic promotion of PAL cellulose was significantly better than that ofγirradiation.This study provides a theoretical basis for the application of irradiation technology in lignocellulose pretreatment.