Irradiation Pretreatment For Enzymatic Hydrolysis Of Wheat Straw

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.