Pretreatment of cocoa waste using ionic liquid for bioethanol production

Abstract

Bioethanol is a fuel derived from renewable sources of feedstock typically plants and agricultural waste such as cocoa waste. It has improved 'Lifecycle CO2' performance because the plants used as feedstock take CO2 from the atmosphere as they grown. This means that almost all the CO2 produced by burning the fuel is balanced by CO2 taken from the air. The reduced CO2 emissions indicate that bioethanol is good for the environment. But unfortunately most of the chemicals used in the pretreatment processes for bioethanol production are not environmentally benign. In this study we employed the used of ionic liquid which is environmentally friendly in the pretreatment of coca waste, so that the whole process will be “green” (environmentally benign). To determine how effective Ionic liquid pretreatment is, it was compared to the untreated cocoa waste, sulphuric acid pretreatment and sodium hydroxide pretreatment. Ionic liquid pretreatment was found to showed minimal biomass destruction of 30.77% after pretreatment while H2SO4 showed 61.18% and NaOH 78.89% of biomass destruction after pretreatment. The untreated biomass has 10.23% amount of cellulose but pretreatment with ionic liquid exposed this amount up to 47.30%, H2SO4 to 49.13% and NaOH reduced this amount to 7.150%. Two types of yeast were also isolated from Tapai Ubi to do the fermentation. Using DNS method for determining reducing sugar, Ionic liquid pretreatment produced 6.3*10-2g/L of reducing sugar and untreated, H2SO4 pretreatment NaOH pretreatment produced 2.87 *10-2 g/L, 7.4*10-2g/L and 3.37*10-2g/L respectively at the end of 24 hours of incubation. Bioethanol produced during the fermentation was analysed using gas chromatography. Ionic liquid produced a total of 7.885g/L, H2SO4 produced 7.911g/L NaOH produced 6.824g/L and untreated cocoa waste produced 5.116g/L of ethanol at the end of 24 hours