Pretreatment Of Wheat Straw Using Maleic Acid

The effects of conditions of maleic acid pretreatment of wheat straw were investigated onxylose yield and furfural yield. Maleic acid-catalyzed hemicellulose hydrolysis reaction inwheat straw was analyzed by kinetics. In addition, the filtercake after pretreatment was alsoanalyzed by enzymatic hydrolysis. All the above is to improve the comprehensive utilization ofxylose and glucose in wheat straw.The optimal condition of maleic acid pretreatment of wheat straw was as follows: ratio ofsolid to liquid70g/L, reaction time40min, temperature150℃, maleic acid concentration0.1mol/L. Xylose yield reached75%while furfural yield only1.6%on the optimal condition.In the course of reaction, from high to low of sensitivity to xylose yield to the four factorswas temperature, maleic acid concentration, reaction time and ratio of solid to liquid; From highto low of sensitivity to furfural yield to the four factors was temperature, reaction time, maleicacid concentration and ratio of solid to liquid.The effect of maleic acid was lower than that of sulfuric acid on the conversion processfrom xylose to furfural at higher temperatures. On the condition of temperature170℃, maleicacid concentration0.1mol/L, time40min, ratio of solid to liquid70g/L, the furfuralconcentration after maleic acid pretreatment was0.52g/L while it was1.49g/L after sulfuric acidpretreatment.The formation courses of xylose and furfural were satisfactorily described by Saemanmodel. The production rate constant and the decomposition rate constant at differenttemperatures were determined by curve fitting. Meanwhile, the activation energy of xyloseformation was determined120.43kJ/mol using Arrhenius equation.When the filtercakes were treated using cellulase, the glucose yield of the filtercake bymaleic acid was a little higher than that of the filtercake by sulfuric acid.The FT-IR spectra indicated that hemicellulose was mainly removed during maleic acidpretreatment. The SEM showed that obvious cracks and lots of pores appeared in the surfacesof wheat straw after the pretreatment.Therefore,pretreatment of wheat straw using maleic acid can effectively removehemicellulose and reduce the yield of the fermentation inhibitors such as furfural. Meanwhile,itcan also insure the high glucose yield after the filtercake is treated using cellulase.