International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | March -2017
p-ISSN: 2395-0072
www.irjet.net
Towards Bioethanol Production in Kenya – Enhanced Pretreatment of Prosopis Juliflora Using Ionic Liquids Florence Ajiambo1, Charles Nzila2, Saul Namango1 Department of Chemical & Process Engineering, Moi University, P.O Box 3900-30100, Eldoret Kenya Department of Manufacturing, Industrial & Textile Engineering, Moi University, P.O Box 3900-30100, Eldoret Kenya 1
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Abstract - Lignocellulosic biomass especially from nonfood
crops is widely regarded as a sustainable second-generation bioethanol raw material. However, production of bioethanol from the abundant and inexpensive sources of lignocellulosic biomass such as Prosopis Juliflora requires that the latter undergo pretreatment processes. A new pretreatment method by use of Ionic Liquids has shown to be promising. This research work analyzed pretreatment of Prosopis Juliflora stem using 1-butyl-3-methylimidazolium chloride ([BMIM]Cl),1-butyl-4-methylpyridinium chloride ([4MBP]Cl) and trihexyltetradecylphosphonium chloride ([P66614]Cl). Regeneration of cellulose from the Ionic Liquids was carried out and the performance of the Ionic Liquids established through analysis of glucose concentrations upon hydrolysis. Pretreatment of Prosopis Juliflora was carried out at varied temperatures (80°C–140°C), pretreatment periods (40min– 160min) and a biomass loading of 6%wt. Simple acid hydrolysis was then performed at a temperature of 130°C for a duration of 10 minutes. Finally glucose measurement was done using a Shimadzu UV–Vis Spectrophotometer at a wavelength of 520nm. Pretreatment of the biomass with the ionic liquids resulted in an increase in glucose yield of 1.78 times with phosphonium IL, 18.1 times with imidazolium IL and 15.21 times with pyridinium IL as compared to the unpretreated biomass. Ionic liquid pretreatment is therefore an effective and viable process that can be applied towards unlocking lignocelluloses recalcitrance. However [BMIM]Cl and [4MBP]Cl showed better performance generally as compared to P66614]Cl with respect to maximum glucose yield obtained with each of the ILs (7.19% in the P66614]Cl pretreated case, 73.27% in the [BMIM]Cl pretreated case and 61.63% in the [4MBP]Cl pretreated case. Prosopis Juliflora yielded a substantial amount of glucose hence qualifying as a potential non food-based biomass substitute suitable for bioethanol production. Key Words: Pretreatment, Ionic Liquids, Lignocellulosic Biomass, Prosopis Juliflora, bioethanol, Kenya.
1. INTRODUCTION Energy availability, supply and use play a central role in the way societies organize themselves, from individual welfare to social and industrial development. By extension, energy accessibility and cost is a determining factor for the
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economical, political and social interrelations among nations. Considering energy sources, human society has dramatically increased the use of fossil fuels in the past 50 years in a way that the most successful economies are large consumers of oil. However, geopolitical factors related to security of oil supply, high oil prices and serious environmental concerns (1) have led to a push towards decreased fossil fuel consumption. Given this reality, nations around the world are investing in alternative sources of energy, including bioethanol. The leading nations in bioethanol production (Table 1) are Brazil and the USA (2). Asian countries altogether account for about 14% of world’s bioethanol production. Table-1: Leading Bioethanol Producers In the World (3) Country/Group of countries
Ethanol Production Million litres
MTOE
USA
26,500
14.55
Brazil
19,000
10.44
European Union
2,250
1.24
China
1,840
1.01
Canada
1,000
0.55
India
400
0.22
Others
1,017
0.56
World (Total)
52,007
28.57
MTOE: million tones of oil equivalents
1.1 Lignocellulosic biomass and ethanol production Bioethanol production from sugarcane and starch rich feedstock such as corn, potato, etc., is considered first generation process and it has already been developed. However, the long-term viability of this process is in question because it will require significantly increased amounts of cultivatable land and significant hike in food prices that will ultimately lead to food insecurity (4). Estimates clearly point to the fact that first generation ethanol production process cannot sufficiently meet the
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