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Development and optimization of the production of first and second generation ethanol from sweet potato (Ipomoea batatas Lam. (L))

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Author(s):
Kallyana Moraes Carvalho Dominices
Total Authors: 1
Document type: Doctoral Thesis
Institution: Universidade Estadual de Campinas, Faculdade de Engenharia Química
Defense date:
Abstract

The demand for clean and renewable sources has stimulated the development of new technologies as alternative to the conventional processes, such as the biofuels production. The use of amylaceous sources and lignocellulosic materials appears as a promising alternative for the production of first (1G) and second (2G) generation ethanol due to their low cost and renewable and sustainable characteristics. In this context, the sweet potato (Ipomoea batatas) has been considered a potential substrate for the alcoholic fermentation since it presents high levels of starch, from 32 to 70%. Industrial sweet potatoes developed for the production of bioenergy are selected due to their higher level of starch and better yield of ethanol, such as the cultivar "Duda". Therefore, the aim of this work was to investigate, evaluate and optimize the production of 1G and 2G ethanol from root and branches of sweet potato, respectively. In order to obtain the 2G ethanol the acid hydrolysis of sweet potato branches was carried out varying the load of solids [10, 20 and 30% (w/w)], sulfuric acid concentration [1.0, 2.0 and 3.0% (w/v)] and time (15, 30, 60 and 90 min) at 121°C. Then, the experimental data were statistically investigated obtaining the optimized conditions of 22% (w/w) loading of solids, 2.5% (w/v) of sulfuric acid concentration and time of 30 min. For the production of 1G ethanol from sweet potato roots an experimental design was performed in order to obtain the optimization of two steps of enzymatic hydrolysis, liquefaction and saccharification, evaluating the load of solids, dose of enzymes, temperature and time. The optimized conditions for the liquefaction step were the following: 15% (w/w) load of solids, 0.76% (v/v) dose of ?-amylase, temperature of 79°C and time of 89 min. The optimization of the saccharification step was found in the condition of 0.50% (v/v) dose of amyloglucosidase, 50°C and 40 min. Under these conditions, sugar concentrations of 172.22 g.L-1 glucose, 21.04 g.L-1 sucrose, 53.59 g.L-1 fructose and 9.05 g.L-1 cellobiose were obtained. Thus, these results showed the potential of sweet potato as raw material for the production of first and second generation ethanol and its use would increase the biofuel production from renewable and sustainable sources (AU)

FAPESP's process: 08/57873-8 - An integrated process for total bioethanol production and zero CO2 emission
Grantee:Rubens Maciel Filho
Support type: Program for Research on Bioenergy (BIOEN) - Thematic Grants