Bioethanol Production from Residual Tobacco Stalks

Aims: In this work, bioethanol production from residual tobacco stalks was investigated.

Place and Duration of Study: Stalks sampling was in South Brazil crops and experiments in chemistry laboratories at Unisc, after tobacco leaf harvest.

Methodology: Pretreatments were conducted with sulfuric acid solution (1 to 3%) in an autoclave (121°C) for 30 to 90 min. Enzymatic hydrolysis was performed with two enzymes, CTec2 and HTec2 (Novozymes). Fermentation (Saccharomyces cerevisiae) was conducted with hydrolysate obtained in selected conditions of acid pretreatment and enzymatic hydrolysis.

Results: In enzymatic hydrolysis, 38.1% glucose was obtained from the pretreated solid. The ethanol yield was 0.06 to 0.19 g of ethanol per g of dried and milled tobacco stalk. The results showed that it is possible to use this biomass for the ethanol production; however, some saccharification variables can still be modified to increase the conversion.

Conclusion: Thus, tobacco stalk, which has no economic value, appears to be a source of monosaccharides for the fermentation and production of bioethanol. Furthermore, the exploitation of tobacco stalks may be of great importance to agriculture and industry as currently over 300,000 ha of land in Southern Brazil is used for tobacco production, and after harvesting, the stalks simply remain unused in the soil.