Research On The Preparation Of Ethanol By Utilizing Of Crop Straw

Biomass (fuel ethanol) with its unique advantages is usually referred to as themost promising renewable alternative energy.There are a large amount of strawsresources in China，promote the rationalization of the use of them，which has an veryimportant significance on the slow energy issues，reduce pressure on the environmentand promote the development of agriculture.In this topic，select the crop straw(cornstalks) as the object of the study，conducted research related to the process(dilutesulfuric acid pretreatment，enzymatic hydrolysis and simultaneous saccharificationand fermentation of treated straw)of using straw to prepare ethanol by fermentation.Using dilute sulfuric acid to pretreat straw，explore the impact of changes intemperature、sulfuric acid concentration、time and solid-liquid ratio on the process，and optimized using response surface methodology and get：the solid-liquid ratio is10%，dilute sulfuric acid concentration is1.07%，temperature is121.59°C and time is60.84min，treatment is better，reducing sugar rate is31.98%，Reducing sugar yieldreach32.6%in the experimental verification of this condition.Characterization the treated straw，SEM images show that straw occurs differentdegree of fracture，the surface becomes fluffy and has a lot of voids，such ashoneycomb shape.FT-IR analysis:the strength of hemicellulose characteristic peaks1740.5cm-1is weakened，know it occurs degradation；the characteristic peak of ligninis1648.9cm-1and1513.6cm-1，intensity of them are slightly reduced，indicating partialdecomposition；characteristic peak of cellulose peak is1421.7cm-1、1384.7cm-1and898.1cm-1，Changes before and after treatment is not very clear，and slightly decreased，explain that a very small part of it is degraded. XRD display:the degree of crystallinityof straw becomes smaller， more susceptible to degradation.Thermogravimetricanalysis found that the degradation temperature of straw is decreased，the role ofactivity is increased,ie the peak moves to the left.Examine the enzymatic hydrolysis process，get the optimum parameters:enzymedosage is25FPU/g(substrate),substrate concentration is65.28g/L，temperature is48.7°C，pH is4.78and time is38.64h，enzymatic hydrolysis rate of up to41.97%，verify the enzymatic hydrolysis rate is40.8%.Non-ionic surface active agent Tween20、Tween80and PEG6000have different degrees of strengthening effect onthe enzymatic hydrolysis，ionic surfactant SDS is not conducive to enzymatic.Whentween reagent dosage is small，enhancement effect of Tween80than Tween20isobvious；when the amount is more，they have little difference stimulative effect onEnzymatic hydrolysis.Tween80in the amount of0.05g/g(substrate),enzymatichydrolysis rate reach up to50.4%and Tween20in the number of0.06g/g(substrate)，enzymatic hydrolysis rate is best reach49.2%，followed by an increase of9.6%and8.4%respectively.It is found that SSF better condition:fermentation temperature is37°C，inoculumscale is10%，continued time is72h，the cellulase dosage is30FPU/g and rotate speedis120r/min，ethanol yield can reach0.132g/g.Gas chromatographic analysis showedthat the retention time of standard sample of anhydrous ethanol’s peak(#1) is1.853min，which of product’s peak (#1) is1.879min，the difference between them is0.026min，both in1.8min around，can determine the product is ethanol.