By growing the population over the world and the industrialization of countries, the energy demand has been increased. At the same time, shortage and depletion of oil resources, has increased attentions towards biofuel production as a clean and renewable energy resources. Lignocellulosic materials are one of the renewable and cheap sources which are abundantly available. In this study, after physical treatments, alkaline pretreatment were performed with 8% (w/v) NaOH and 0.5 molar Sodium carbonate. This means that some of the substrate were treated with 8% (w/v) NaOH at three different temperatures (0, 25 and 93 °C) for 2 h on pine and poplar woods and rice straw. The rest were treated with 0.5 molar Sodium carbonate at three different temperatures (0, 25 and 93 °C) for 3 h on pine and poplar woods and rice straw. Alkaline pretreatment by increasing hydrolytic enzymes accessible surface area and decreasing the cellulose crystallinity, degree of acetylation of hemicelluloses, and delignification, can modify the structure of lignocellulosic materials. To study the effect of the pretreatment, enzymatic adsorption-desorption was conducted on the untreated and pretreated samples at 4 °C for 2 h. Also enzymatic hydrolysis was performed on these samples at 45 °C for 72 h. with 20 FPU cellulose. In this step used 20 FPU cellulose per grams of substrates. XRD analysis of samples showed amount of structural uniformity and crystallinity. SE test and BET analysis was done for examine pores of samples that represent alkaline pretreatment positive effect at 93 °C on pore formation and increase surface area. Although no logical relation obtained from BET and XRD analysis. For both kinds of wood and rice straw, maximum water swelling in water adsorption capacity was observed for the pretreated samples at 0 °C. As well as alkaline pretreatment had been a significant effect on resistance to buffering capacity of pine and poplar woods and rice straw. The enzymatic hydrolysis results show that Most sugar release have been for pretreated pine and poplar woods and rice straw at 93 °C were values of 4.29, 9.19 and 54.38 mg per ml, respectively. Maximum inaccessible water conducted to pretreated samples at 93 °C. In most cases amount of lignin in pretreated samples at 93 °C is minimum. The greatest amount of enzyme desorption is related to the rice straw pretreated at 93 °C. In this study, the best model for enzyme adsorption onto the substrate was Langmuir.
