Process Optimization For Sugars Production From Rice Straw Via Pretreatment With Sulfur Trioxide Micro-thermal Explosion

The wide use and increasingly exhausted of fossil fuels and oil, the energy andenvironment problem are increasing severity, seeking a new generation of renewablegreen energy become the focus of people to study. Straw, forestry waste, is the mostabundant renewable resources of the globe, annual capacity of nearly700milliontons by China alone, thus studying the use of straw get more and more researchers’attention. However, due to the elemental composition, the chemical bonds type andchemical composition of the crops straw are very complex, therefore, the refiningtransformation process, which from solid raw materials to the solid or the liquidproducts, is untoward compared to traditional oil refining process.This paper is based on the existing SO₃micro thermal explosion collaborativedilute alkali treatment method of the laboratory, further investigates the factorsaffecting of SO₃micro thermal explosion treatment and analyzes the causes andways of SO₃micro thermal explosion treatment. Based on all the results, get themain influence factors of SO₃micro thermal explosion collaborative dilute alkalitreatment by Plakett-Burman design screening experiment,, and optimize the mainfactors by Box-Behnken design and response surface methods. Over the course ofthe study and analysis, the key conclusions list following:1. Temperature of SO₃micro thermal explosion has a significant effect on thechemical structure and the subsequent saccharification of rice straw. Along with theincrease of temperature,1625cm-1place-C=O vibrating peaks disappear on the IRspectrum, and is not conducive to the improvement of the subsequentsaccharification rate.2. The effect of increase oleum volume is not obvious on the alteration of thechemical structure. Total sugar production rate of pretreated-straw increase afterrising dropped with the increase of micro thermal explosion solid-liquid ratio, andsolid-liquid ratio is1:4,30IU/g substrate, the saccharification rate attain to amaximum of93%. The yield of the pentosan is increase after rising dropped with theincrease of micro thermal explosion solid-liquid ratio, and solid-liquid ratio is1:2,50IU/g substrate, reaches the highest0.258. Enzyme solution in the fluid ofsaccharifying mainly contains two kinds of sugar, namely xylose and glucose.3. SO₃micro thermal explosion pretreatment is SO₃could generate sulfuric acid with water, at the same time release a lot of heat, then take place sulphate reactionwith the lignin on the straw surface, and respond quickly. The composition and GPCanalysis of washed-straw showed that with the passage of SO₃micro thermalexplosion time, SO₃can enter into the amorphous area of straw, and generatesulfuric acid with water, then occur esterification reaction with hydroxyl, or sulfuricacid directly hydrolyze polysaccharide substances. The result of the componentanalysis explains that with SO₃micro thermal explosion processing time, SO₃couldthrough the amorphous areas, destroy the link bonds of the crystal surface area, orformats mesh structure or cross linking content on the crystal structure surface.4. The conditions for pretreatment of rice straw were optimized by using PBD,BBD, and RSM. The optimal conditions were found as follows: STEX time at23.3min, liquid-solid ratio at13.3（V/m）, soak temperature at62.2°C. Under theseoptimum conditions, the SR increased by286.3%, compared to untreated rice straw,the SR of only lye treated one merely increased by93.2%. These results showed thatSTEX collaborative dilute lye is an efficient pretreatment method to enhance ricestraw digestion and reduce enzyme dosages.