Promotion mechanisms of microwave and lightwave pretreatments on enzymatic saccharification of water hyacinth

The gas chromatography mass spectrometry (GC-MS) and scanning electron microscope (SEM) were used to study the effects of microwave time, power and combination with lightwave on the hyacinth (eichhornia crassipes) physicochemical properties, reducing sugar yields and hydrolysis byproducts. The reducing sugar yield of only 23.9 mg/100 mg hyacinth leave in the enzymatic hydrolysis was obtained when it was pretreated with the steam explosion and NaOH solution. The reducing sugar yield was increased by 30.1% to 31.1 mg/100 mg hyacinth leave when the microwave and lightwave pretreatments were additionally employed. The 55.4% of potential maximum sugars was released when the hyacinth leave was pretreated with the power ratio of microwave to lingtwave at 30:70 (total power is 700 W) for 1 min. When the microwave power was higher and time was longer, more hydrolysis byproducts such as acetic acid, butanone and furfural were produced due to the further decomposition of the xylose derived from the hemicellulose hydrolysis, which was harmful to the following enzymatic saccharification and fermentative ethanol fuel.