Biobutanol production from cocoa pod husk through a sequential green method: Depectination, delignification, enzymatic hydrolysis, and extractive fermentation

The effect of various treatments on the production of reducing sugar and biobutanol from cocoa pod husk (CPH) through depectination, delignification, enzymatic hydrolysis, and fermentation was studied to obtain the best strategy for sequential processes to valorize CPH to biobutanol. Surfactants of Tween 80, Polyethylene Glycol (PEG) 6000, and Sodium Dodecyl Sulfate (SDS) was added to enhance the performance of enzymatic hydrolysis, and L-cysteine addition to support fermentation by Clostridium saccharoperbutylacetonicum N1–4. The optimum activity of the cellulase was at 0.25 FPU/g. Depectination, microwave-assisted delignification, and 2.5 g/L PEG 6000 addition sequence produced the highest sugar concentration of 9.24 g/L. The highest butanol and acetone-butanol-ethanol (ABE) concentrations of 20.4 g/L and 54.4 g/L, respectively, were obtained using immobilized cells and L-cysteine supplementation. ABE production by extractive fermentation was enhanced using immobilized cells and L-cysteine supplementation.