Comparison of different pretreatment methods based on residual lignin effect on the enzymatic hydrolysis of switchgrass.

Three different pretreatment methods for switchgrass were studied. Aqueous sodium hydroxide (0.5-10% w/v, 90 degrees C, 1h), dilute H(2)SO(4) (0.5-6.0% v/v, 121 degrees C, 1h) and hot water (100 degrees C, 1h) were employed in this study to determine how each method affected the digestibility of switchgrass during enzymatic hydrolysis. Switchgrass pre-treated with 0.5% w/v sodium hydroxide generally produced glucose in higher concentrations than sulfuric acid and hot water pre-treated samples. SEM studies on the pre-treated samples revealed a great deal of pore formation in the NaOH pre-treated samples and little or no physical changes on the acid and hot water pre-treated samples. Lignin analysis carried out on the pre-treated samples showed a considerable decrease in lignin content in the NaOH pre-treated samples and only a slight decrease in lignin content for the other pretreatment methods studied.