THE EFFECT OF ELEPHANT GRASS (Pennisetum purpureum) PRETREATMENT BY MICROWAVE ASSISTED ORGANIC SYNTHESIS (MAOS) AND ITS COFERMENTATION TO THE PRODUCTION OF BIOETHANOL

• Main Author: MARIA DOLFI KOLO (NIM : 20513080), SEFRINUS
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/24243
• Institution: Institut Teknologi Bandung

The increase in population led to the increase in the needs of transportations and industrial activities resulting in the increase in the consumption of fuel. The increase in the consumption of fuel is not in line with the production of oil, therefore the needs to convent the use of fossil fuels into biofuels are increased as well. One alternative biofuels to replace fossil fuels, such as petroleum, is bioethanol. In this study, bioethanol was derived from the biomass conversion of elephant grass (Pennisetum purpureum) as lignocellulosic material that is very potential for the production of bioethanol. The lignocellulosic content of elephant grass can be converted to hexose and pentose sugars (glucose and xylose) through the combination of delignification techniques and acid hydrolysis by Microwave Assisted Organic Synthesis (MAOS) method. The optimum sugar mixtures of hydrolysis product were subsequently converted into ethanol employing two types <br /> <br /> <br /> of yeast, which are Saccharomyces cerevisiae ITB-R58 and Pichia stipitis cerevisiae ITB-R89. The cofermentation of hydrolysis products was carried out by varying the concentrations of inoculum (5, 10 and 20% (v/v)) for 5 days at temperature of 30 °C and pH 4.5. The analysis of lignocellulose content was conducted according to Cheson Datta method. The analysis of the surface morphology of elephant grass powder was determined using scanning electron microscopy (SEM). The reducing sugar analysis was performed by dinitrosalicylic (DNS) method. The analysis of the xylose sugar, ethanol and acetic acid was performed by high performance liquid chromatography (HPLC). The results showed that the pretreatment employing delignification resulted 47,4% cellulose, 24,3% hemicellulose, 10,8% lignin and 10,7% ash and dilute acid hydrolysis techniques using MAOS method at optimum microwave reaction conditions, in which the irradiation power was 400 W, the setting temperature was <br /> <br /> <br /> 95 °C, the microwave duration was 30 minutes and the reaction was held in 2% (v/v) H2SO4 solution, resulted the optimum reducing sugars concentration of about <br /> <br /> <br /> 26,63 g/L that corresponds to 66,57% hydrolysis efficiency. According to the result of HPLC analysis, the optimum inoculum concentration used in the <br /> <br /> <br /> cofermentation process using this inoculum concentration the substrate (glucose and xylose) utilization was about 76,15% resulting ethanol concentration about 10.79 g/L (34.74% yields), with the optimal ethanol productivity rate about 0.45 g/L.days. These result correspond to the fermentation efficiency about 69.48%. This study thus has successfully to obtain bioethanol trough cofermentation technic with two types of yeast, which are Saccharomyces cerevisiae ITB-R58 and Pichia stipitis cerevisiae ITB-R89 by inoculum concentration 10%.