Biphasic pretreatment for energy and carbon efficient conversion of lignocellulose into bioenergy and reactive lignin

Md Khairul Islam, Shazia Rehman, Jianyu Guan, Chun Yin Lau, Ho Yin Tse, Chi Shun Yeung, Shao Yuan Leu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Lignocellulosic biomass is an emerging resource of carbohydrates and bio-based aromatics derived from biorefinery. However, pretreatment of biomass to fractionate building-block chemicals is an energy-intensive process affecting the sustainability of the whole process. This study aims to investigate the energy and carbon benefits of a novel biphasic pentanol-water pretreatment. To compare, three different pretreatment scenarios i.e., dilute acid, conventional ethanosolv, and biphasic pentanol-water pretreatments were investigated for the conversion of Acacia Confusa wood chips to produce benchmark fuel and reactive lignin. The results showed that the proposed biphasic pretreatment yielded 70.3% lignin dissolution in the organic phase while leaving cellulose as an insoluble solid residue. Simultaneous saccharification and fermentation resulted in 92.2% cellulose digestibility of pretreated substrates and ethanol yield of 0.41 g/g-glucan in the fermentation broths. Biphasic pretreatment also preserved 42.5% of reactive β-aryl ether linkages in fractionated lignin which is higher than ethanosolv pretreatment (31.1%). Carbon balance showed that the biphasic process recovered 50.3% wood carbon in the product streams as ethanol and reactive lignin, which is higher than the dilute acid (17.1%) and ethanosolv (49.6%) approaches. The overall energy balance showed that the biphasic process yielded net positive energy of 1.1 MJ/kg-wood which was much higher than the dilute acid (−0.16 MJ/kg) and ethanosolv (−1.6 MJ/kg) processes. This was due to the physical separation of dissolved sugars and lignin which reduced about 32.4% of the total energy consumption compared to ethanosolv biorefinery indicating the feasibility of the proposed biphasic process.

Original languageEnglish
Article number117653
JournalApplied Energy
Volume303
DOIs
Publication statusPublished - 1 Dec 2021

Keywords

  • Bioethanol
  • Biphasic pretreatment
  • Carbon balance
  • Energy footprint
  • Pentanol-water
  • Reactive lignin

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering
  • Energy(all)
  • Management, Monitoring, Policy and Law

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