Using Surface Response Method and Central Composite Design in Optimizing Sugar Production from the Pruning Poplar Tree Waste in Bioethanol Process by Dilute Acid Hydrolysis

Limited fossil fuel resources and increasing need for fuel, air pollution and the need for green fuels have led to bioethanol being considered as a renewable energy source. This fuel is mainly produced from plants and crops. In order to determine the effective parameters on the production of fermentable sugar, dilute acid hydrolysis of Poplar waste in the bioethanol process has been used as a surface response method and central composite design. The wood was first washed with distilled water and dried in air and sunlight, ground by a vibrating disc grinder up to 50 μm and stored in zipped plastics in room air and then hydrolyzed at certain temperatures in an acidic solution in an autoclave. To investigate the effect of the three main variables of acid concentration, temperature, and time on the fermentable sugar produced, temperature at 3 levels of 140, 160, and 180 ° C acid concentration at 3 levels of 0.5,1, and 1.5% and time in 3 levels of 5, 10, and 15 min were selected. By using Molisch, Barford, and Resorcinol quality tests, the major constituents of the refined product were identified as glucose. Glucose concentration was measured using the line anion method and modeled by a two-squared equation. The results showed that in the defined range glucose production was affected by the second power of temperature and then the concentration of acid and to a small extent is affected by time. At high temperatures and concentrations of acid and medium time, most of the glucose products can be produced.