【作者】 沈志强；

【导师】 杨春平； 王建龙；

【作者基本信息】 湖南大学 ， 环境工程， 2008， 硕士

【摘要】 可再生能源是一个应对能源短缺和环境恶化的有效途径之一。而生物质能源作为储量最为丰富的可再生能源之一,近年来受到了越来越多的关注。利用木质纤维素生成生物乙醇或其它生物制品的瓶颈是如何有效的破坏原料的结构以增加其反应性能。很多方法被广泛的应用于木质纤维素原料的预处理,如物理、化学、物理-化学、生物方法等。本文研究了γ射线辐射预处理麦秸的辐照效应及辐照后效应。实验结果表明,辐照预处理能明显破坏麦秸的结构。随辐照剂量增加,麦秸质量损失增大,粒度分布向细颗粒方向迁移。辐照与粉碎结合预处理有明显的协同效应,较适宜的预处理条件为500 kGy、粒度为140目,葡萄糖得率为10.2%。辐照后效应对麦秸酶解产糖有明显的影响,以50、100、200、300和400 kGy辐照的麦秸酶解,其辐照后效应与初始效应的比值分别为12.9%、14.9%、8.9%、9.1%(产还原糖)和20.1%(产葡萄糖)。通过考察辐照剂量、辐照与NaOH组合顺序、NaOH浓度、NaOH浸泡时间等因素,研究了用100 kGy剂量辐照与NaOH温和浸泡协同预处理工艺。通过对还原糖得率、组分改变、表面形态、结晶度等的分析,对该协同工艺的作用机理进行了探讨。实验结果表明,辐照与NaOH协同预处理,可以大大提高还原糖得率,协同效应明显。较适宜的组合预处理工艺为100 kGy辐照加2%NaOH浸泡1 h后,其酶解还原糖得率达到理论产率的78.2%。单纯用100 kGy剂量辐照对麦秸的组分、表面形态及结晶度的改变不明显,但可以大大降低后续碱浸泡所需的用量和时间。对100 kGy辐照加2%NaOH浸泡1 h的小麦秸秆的酶解条件进行了优化,其最佳酶解参数为:酶的用量为50 mg/g底物,底物量为1 g/50 ml缓冲液,温度为50℃,pH为4.8,酶解时间为48 h。在此条件下,小麦秸秆的酶解还原糖得率为80.15%。更多还原

【Abstract】 The renewable energy is an alternative way to cope with the current energy shortage and the climate change. The biomass energy, as one of the renewable energy source, has received increasing attention in recent years. The bottleneck of the utilization of biomass for the production of biofuel or bioproducts is the disruption of cellulose, usually the chemical hydrolysis, mechanical abrasion methods have been used. However, there are some drawbacks, such as low efficiency and the negative effect of hydrolysis products on the further bioconversion. Therefore it is necessary to develop the new technology. This paper reported a pretreatment technology, that is, the application of ionizing irradiation technology for the pretreatment of wheat straw to improve their enzymatic hydrolysis. It is shown that irradiation can cause significant breakdown of the structure of wheat straw. The weight loss of wheat straw increased and the size distribution after crushing moved to fine particles at elevated irradiation doses. A synergistic effect between irradiation and crushing was observed, with a glucose yield of 10.24% at a dose of 500 kGy with powder of 140 mesh. The aftereffect of irradiation had important impact on enzymatic hydrolysis of wheat straw. The aftereffect (at 22nd day) of 400 kGy irradiation accounted for 20.0% of the initial effect for glucose production, and the aftereffects of 50, 100, 200 (at 9th day) and 300 kGy (at 20th day) accounted for 12.9%, 14.9%, 8.9% and 9.1%, respectively, for reducing sugar production.Gamma ray irradiation and alkali solution pretreatment of wheat straw and its effect on enzymatic hydrolysis were also studied in this paper. The result showed that irradiation can significantly decrease the concentration of alkali solution and shorten the pretreated time, though the changes in the physical and chemical properties of only irradiated wheat straw are indistinctively. A synergistic effect between irradiation and alkali solution pretreatment was observed, with a reducing sugar yield of 78.2% (accounted for theoretical yield) after irradiation at a dose of 100 kGy and then with2% NaOH pretreated for 1 h. And the optimum conditions for saccharification this pretreated wheat straw were 50 mg/g (cellulose/substrate), 50℃, 1 g/50 ml (substrate/buffer), pH 4.8, 48 h.更多还原