Optimization and comparison of induction heating and LPG assisted acid pretreatment of cocoa pod for ABE fermentation

Abstract

Rapid depletion of petroleum fuels with high fluctuating market prices have enforced mankind to switch for an alternate fuel. The present investigation reports a comparison on the effect of Induction heating and LPG heating for acid hydrolysis of cocoa pod biomass (CPB) to carryout ABE fermentation for the production of biobutanol. The effect of Sulphuric acid (H2SO4), CPB load and residence time on release of total sugar was studied and optimized using Central Composite Design (CCD). The optimum condition for the pretreatment by induction heating was found to be 3.05 (%v/v) of H2SO4, 11.51 (%w/v) of CPB and 41.43 min of residence time with 36.26 g/L of total sugar. Similarly for LPG heating an optimum of 25.66 g/L of total sugar released with pretreatment condition 4.03 (%v/v) of H2SO4, 6.53 (%w/v) of CPB and 64 min of residence time was observed. The treatment of high biomass load with low concentration of acid in lesser time makes induction heating energy efficient and cost effective. The CPB hydrolysate produced through Induction and LPG heating was allowed to undergo anaerobic fermentation, using Clostridium acetobutilicum MTCC11274. The ABE yield produced using induction assisted CPB hydrolysate was 5.04 ± 0.32 g/L of acetone, 11.73 ± 0.84 g/L butanol and 1.43 ± 0.04 ethanol in 312 h with total ABE of 18.25 ± 1.17 g/L. The resulted ABE fermentation yield was higher than the LPG assisted CPB hydrolysate with 1.69 ± 0.17 g/L acetone, 3.36 ± 0.27 g/L butanol and 0.22 ± 0.08 g/L ethanol with total ABE of 5.27 ± 0.51 g/L. The less energy consumption, higher conversion of carbohydrate and great fermentability of hydrolysate makes induction assisted acid pretreatment method significant in biofuel industry.