Journal of Advanced Materials Science and Engineering
Open AccessBio-Ethanol Production from Cocoyam (Xanthosoma Sagittifolium) Peels using Acid Hydrolysis
Authors: Nnaji AC, Mbah GO, Okorie O.
Abstract
This research explored bioethanol production from cocoyam peels using two acid hydrolysis methods— hydrochloric acid (HCl) and sulfuric acid (H2SO4) with acid concentrations ranging from 0.1 to 1 M. Before hydrolysis and fermentation, the cocoyam peels were pretreated, and their proximate composition was analyzed. The study investigated how hydrolysis time, pH, temperature, and acid concentration influenced ethanol yield. To optimize sugar yield from acid hydrolysis, the Box-Behnken design within Response Surface Methodology (RSM) was applied. Results showed that sugar yield increased with temperature up to 150°C but declined beyond this point, with a significant decrease observed at 170°C. At 150°C, sugar yield was notably higher than at 130°C and 170°C. The effect of hydrolysis time varied with temperature: below 170°C, maximum sugar yield was reached before 150 minutes, whereas at 170°C, the peak occurred after 60 minutes. Importantly, simple sugar yields from HCl and H2SO4 hydrolysis were almost identical. The highest ethanol yield obtained from the acid hydrolysate was 4.55% (v/v). These findings indicate that cocoyam peels, containing approximately 50% carbohydrates, are a promising raw material for bioethanol production.
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