Synthesis of Bioethanol from duckweed

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Addis Ababa University


Duckweed can be utilized to produce ethanol, butanol and biogas, which are promising alternative energy sources to minimize dependence on limited crude oil and natural gas. The advantages of this aquatic plant include high rate of nutrient (nitrogen and phosphorus) uptake, high biomass yield and great potential as an alternative feed-stock for the production of fuel ethanol, butanol and biogas. This study involved ethanol production from duckweed and optimization of acid hydrolysis for maximizing glucose concentration and ethanol yield. The conversion of duckweed to ethanol can be achieved mainly by four process steps, pretreatment of duckweed to remove different contaminates, dried at 60 °C for 24h and ground to the particle size of 2 mm, After soaking in diluted acid hydrolysis of pretreated duckweed to convert starch into reducing sugar (glucose), fermentation of the sugars to ethanol using Saccharomyces cerevisiae and finally distillation. Duckweed washed in order to remove the different contaminates, hydrolysis was carried out. In order to obtain ethanol yield, optimal value of factors for hydrolysis was determined by Response Surface Methodology (RSM) using Central Composite Design (CCD). The optimum combination of temperature, acid concentration, and time was determined. Twenty runs for each sample were carried out and analyzed using Design Expert 7.0 software, to investigate the effects of hydrolysis parameters on yield of ethanol. High yield of bioethanol 4.57ml/20g (0.18g/g) as obtained at the optimum, temperature of 1000C, acid concentration 0.8M and time 120min. ANOVA (statistical analysis) showed that an ethanol yield of 4.332211/20g sample (0.17g/g) was obtained at a temperature of 103.59 0c ,0.91M and 2.45 hr. generally The production of bioethanol from duckweed could be an option for energy and other uses. Keywords: Bioethanol, duckweed, hydrolysis, fermentation and Saccharomyces cerevisiae



Bioethanol; duckweed; hydrolysis; fermentation and Saccharomyces cerevisiae