Analysis Of Fermentation Inhibitors During The Radiation Pretreatment Of Lignocellulosics And Research On The Influence Of Ethanol Fermentation

Pretreatment is one of the key working procedure of lignocellulose extract fuel ethanol, because lignocellulose can’t be direct hydrolysised, it needs pretreatment process to break the physical and chemical structure, promote its hydrolysis. 60Co gamma irradiation is an effective pretreatment method, it can break the structure of lignocellulose, prompting cellulase enzyme digesting cellulose effectively, improve the ethanol conversion rate. But 60Coy irradiation will produce some fermentation inhibitors.The paper built an HPLC method identify the three types of fermentation inhibitors （benzene series compounds such as vanilli、vanillic acid、p-hydroxy benzoic acid、 4-hydroxy benzaldehyde、p-coumaric acid、syringic acid, furan derivatives such as furfural and organic acids such as formic acid, acetic acid） at the same time. Then the test used this method to separate and quantitative analyze the inhibitors of 60Coy radiated miscanthus, 60Coy radiated reeds and 60Coy radiated rape straw, in order to systematically compared the concentration change of the by-products of three kinds of material between 0-1200kGy 60Coy radiation. Finally the test choosed 1200kGy irradiated miscanthus do the experiment of Ca（0H）₂ alkalify and activated carbon adsorpt, analyzed the treatment effect of the inhibitors removing and the influence of inhibitors for ethanol production.The main results were summarized as follows:1、 According the properties of the target fermentation inhibitors, the test selected detection wavelength, mobile phase（type, pH, buffer salt）, flow velocity, column temperature and elut gradient. Then the separation was carried out on a C18 column with the mobile phase of acetonitrile-0.01mol （NH4）2HPO4 （phosphate adjust to pH=2.7） at 25℃ at a flow rate of 0.8mL/min and the detection wavelength was multi-wavelength, Under the optimized conditions, the correlation coefficients of the 9 compounds were between 0.9995 and 1.0000.The recoveries of the 9 compounds were all above 96%,the relative standard deviations being 1.5%-2.3% and detection limits being 0.1-0.89 mg/L. This method is suitable for the determination of the target fermentation inhibitors during the 60Coy radiation pretreatment of lignocellulosics.2、The test used the high performance liquid chromatography （HPLC） method find that the concentration of the inhibitors of material from high to low in turn was:organic acid（formic acid, acetic acid）, benzene series compounds, furan derivatives （furfural）.And with the increase of irradiation dose, the concentration of the by-products in three kinds of raw materials were overall increasing. In the water extraction of 3 kinds of raw materials after Doses of radiation, reed have the benzene series compounds was the highest, it was 149.38mg/L during 1200kGy irradiation.rape straw have the organic acid was the highest, it was 600mg/L during 1 OOOkGy irradiation.3、The test choosed 1200kGy irradiation miscanthus do detoxification treatment, the results showed that the overliming might remove a small amount of the by-products and activated carbon adsorption could remove most of by-products, but activated carbon also made the amount of sugar loss much, was 30%.Compared detoxification raw material with the non-detoxification raw material do fermentation experiment, found that after 24h,overliming treated miscanthus generate ethanol concentration was 3.22g/L, activated carbon adsorption of irradiation miscanthus generate ethanol concentration was 3.44g/L, and irradiation miscanthus generate ethanol concentration was 3.50g/L.