Isolation, optimization, liquefaction, and characterization of lignin from agricultural wastes

Authors

  • Alaba Joseph Adebayo Olusegun Agagu University of Science and Technology, Okittipupa, Nigeria.
  • Joseph Kolawole Ogunjobi Federal University of Technology Akure
  • Olugbenga O Oluwasina Federal University of Technology Akure
  • Labunmi Lajide Federal University of Technology Akure

DOI:

https://doi.org/10.48422/IMIST.PRSM/ajees-v8i4.34570

Keywords:

Bio-polyol, Renewable-chemicals, Plant-Biomass, Delignification

Abstract

Environmental concerns have triggered the search for green chemicals for the replacement of fossil-based chemicals. The need for a cleaner environment is the pivot for the search for green chemicals from biomass as a replacement for the fossil-based chemicals. Thus, the present study focuses on the isolation, optimization, liquefaction, and characterization of lignin from agricultural wastes namely:  ground nutshell (GNS), palm front base (PFB), palm kernel shell (PKS), male palm fruit (MPF) and baobab pod shell (BPS). Lignin yield was optimized by varying concentrations of sodium hydroxide, biomass to liquor ratio, time, and temperature. From the results, PKS had the highest lignin yield (100 %) while GNS gave the lowest yield (13.7%). The best optimization condition was 25% w/v NaOH concentration, 130 oC, and biomass to liquor ratio 1:40 for PKS for a period of 120 min. The lignin obtained from PKS was liquefied, using polyethylene glycol 400 (PEG400) and ethylene glycol (EG) as liquefying solvents. However, the lignin for gas chromatography-mass spectrometer (GC-MS) analysis was isolated using the copper alkaline extraction method.  Lignin samples were characterized using Fourier Transform Infrared (FTIR) spectroscopy and gas chromatography-mass spectrometer (GC-MS). The results obtained from the characterization showed monomeric phenolic products with fewer ether bonds present. Similarly, the extent of liquefaction and the quality of liquefied products (bio-polyol) from the respective solvents used were observed. The two bio-polyols (PEG400 and EG) had hydroxyl numbers: 450 mg KOH/g and 445 mg KOH/g, liquefaction yield: 93.22% and 92.22%, and residue contents: 3.39% and 3.49% respectively. The qualities of the obtained bio-polyol are suitable for rigid bio-based foam synthesis.

Author Biographies

Alaba Joseph Adebayo, Olusegun Agagu University of Science and Technology, Okittipupa, Nigeria.

Department of Chemistry 

PhD Student 

Joseph Kolawole Ogunjobi, Federal University of Technology Akure

Lecturer/Researcher 

Department of Chemistry 

Olugbenga O Oluwasina, Federal University of Technology Akure

Lecturer/Researcher 

Department of Chemistry 

Labunmi Lajide, Federal University of Technology Akure

Professor of Chemistry 

Department of Chemistry 

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Published

30-12-2022

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Section

Articles