Kraft lignin from Jackfruit waste as an adsorbent for the selective recovery of biobutanol from the Acetone-Butanol-Ethanol fermentation broth

Abstract

Lignin, a naturally occurring aromatic heteropolymer can be used for the selective recovery of biobutanol from fermented broth due to the presence of functional groups such as hydroxyl and carbonyl. In the present work, kraft lignin was extracted from Jackfruit (Artocarpus heterophyllus Lam) waste (JFW), characterized and tested for the selective recovery of butanol from model solutions and Acetone-Butanol-Ethanol (ABE) fermented broth by adsorption-desorption. Fourier Transform Infra-Red (FTIR) spectra of the extracted kraft lignin displayed characteristic bands of the aromatic rings and monomeric functional groups. X-ray diffraction (XRD) analysis demonstrated lignin diffraction peaks at 25° and 32°. Jackfruit waste kraft lignin recorded a high thermal decomposition temperature (Td) and glass transition temperature (Tg) of 180 °C and 145 °C denoting high thermal stability. Isotherm and kinetics experiments disclosed a maximum butanol adsorption capacity (Qmax) and equilibrium time of 214.59 mg/g and 55 min of Jackfruit waste kraft lignin. Ex-situ recovery of biobutanol from the Acetone-Butanol-Ethanol fermented broth using Jackfruit waste kraft lignin recorded a 25% increase in butanol titre compared with the initial solvent concentration in the broth. The present results confirm the selective adsorption of butanol by the isolated Jackfruit waste kraft lignin from the Acetone-Butanol-Ethanol fermented broth. Using lignin as an adsorbent to selectively recover biobutanol will solve the long-standing bottleneck of Acetone-Butanol-Ethanol fermentation.