Optimization Of Pretreatment Conditions For Saccharification And Fermentation Of Maize Straw

This topic used Maize Straw as raw material to optimize the pretreatment conditions of Maize Straw,and the content of cellulose,hemicelluloses and lignin was measured to reduce environmental pollution,reduce production cost and increase yield in the production process.Some physical and chemical technologies,such as mechanical pulverization technology,high temperature hydrothermal technology,dilute acid and alkali treatment technology,steam blasting technology,etc.,using a combination of various pretreatment methods to separate cellulose,hemicelluloses,and lignin,and cut off the connection between them and destroyed the crystal structure,reduced the degree of polymerization,effectively removed lignin,and improved the conversion utilization of cellulose and hemicelluloses.The corn straw was immersed in a sodium bisulfite solution with a concentration of 0.14% at 85 °C.After rinsing with water,the two processes of squeezing and not squeezing were respectively carried out,and steam explosion and cooking were carried out under different pressure conditions,and the temperature control was controlled.At 180-200 °C,the treatment time was 15 min,soaked in a water-sealing condition of 5% ammonia water at 85 °C to separate solid matter and liquid.The liquid containing ammonia water was diluted with sulfuric acid to adjust the p H<4 and the lignin was extracted by suction filtration.After dry weighing,the filtered liquid was diluted and autoclaved,and then subjected to liquid chromatography analysis.The solid material was washed with water until the p H was neutral,dried and pulverized in a dry box,and subjected to autoclave and subjected to liquid chromatography analysis.The standard sample SRS was also subjected to liquid chromatography analysis.By examining the effects of soaking time,extrusion process,steam explosion cooking process and different pressures on cellulose,hemicelluloses and lignin,the experimental results were as follows:1.The optimum time for soaking sodium bisulfite solution was 24 h,and the optimum time for soaking ammonia solution was 2h.2.Under the condition of unsuited steam explosion,the pressure of 3.0MPa was better,and the cellulose,hemicelluloses and lignin content were reduced by 18.76%,19.95% and 14.54%,respectively.3.Under the condition of squeezed steam explosion,the pressure of 3.0MPa was better,and the cellulose,hemicelluloses and lignin content were reduced by 18.46%,18.91% and 13.10%,respectively.4.Under uncooked cooking conditions,the pressure of 3.0MPa was better,and the cellulose,hemicelluloses and lignin contents were reduced by 15.35%,20.16% and 15.84%,respectively.5.Under squeezed cooking conditions,the pressure of 3.0MPa was better,and the cellulose,hemicelluloses and lignin contents were reduced by 15.47%,20.04% and 14.94%,respectively.The experimental results showed that the use of various pretreatment methods could effectively reduce the lignin in corn straw and improve the conversion efficiency of cellulose and hemicelluloses.The optimum conditions were determined by the experimental results.The soaking time of sodium bisulfite solution was 24 h,the steam explosion was not squeezed,and the soaking time of ammonia solution was 2h under the pressure of 3.0MPa,which reduced the cellulose,hemicelluloses and lignin of the straw sample by 18.76%,19.95% and 14.54%.