From unavoidable food waste to advanced biomaterials: microfibrilated lignocellulose production by microwave-assisted hydrothermal treatment of cassava peel and almond hull

Allyn P. Sulaeman, Yang Gao, Tom Dugmore, Javier Remón, Avtar S. Matharu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Lignocellulose based nanomaterials are emerging green biosolids commonly obtained from wood pulp. Alternative feedstocks, such as as unavoidable food waste, are interesting resources for nano/microfibers. This research reports the production and characterization of microfibrillated lignocellulose (MFLC) from cassava peel (CP) and almond hull (AH) via acid-free microwave-assisted hydrothermal treatment (MHT) at different temperatures (120–220 °C). During processing, the structural changes were tracked by ATR-IR, TGA, XRD, 13C CPMAS NMR, zeta potential, HPLC, elemental analysis (CHN; carbon, hydrogen and nitrogen), TEM and SEM analyses. The microwave processing temperature and nature of feedstock exerted a significant influence on the yields and properties of the MFLCs produced. The MFLC yields from CP and AH shifted by 15–49% and 31–73%, respectively. Increasing the MHT temperature substantially affected the crystallinity index (13–66% for CP and 36–62% for AH) and thermal stability (300–374 °C for CP and 300–364 °C for AH) of the MFLCs produced. This suggested that the MFLC from CP is more fragile and brittle than that produced from AH. These phenomena influenced the gelation capabilities of the fibers. AH MFLC pretreated with ethanol at low temperature gave better film-forming capabilities, while untreated and heptane pretreated materials formed stable hydrogels at solid concentration (2% w/v). At high processing temperatures, the microfibrils were separated into elementary fibers, regardless of pretreatment or feedstock type. Given these data, this work demonstrates that the acid-free MHT processing of CP and AH is a facile method for producing MFLC with potential applications, including adsorption, packaging and the production of nanocomposites and personal care rheology modifiers. Graphic abstract: [Figure not available: see fulltext.]

Original languageEnglish
Early online date28 Jun 2021
Publication statusE-pub ahead of print - 28 Jun 2021

Bibliographical note

Funding Information:
APS would like to thank Lembaga Pengelola Dana Pendidikan (LPDP) scholarship, Ministry of Finance, Indonesia, for financial support for PhD study under the guidance of ASM. JR would like to express his gratitude to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva fellowships (FJCI-2016-30847 and IJC2018-037110-I) awarded. ASM acknowledges the EPSRC (Whole systems understanding of unavoidable food supply chain wastes for re-nutrition EP/P008771/1) for funding TD for Postdoctoral study.

Publisher Copyright:
© 2021, The Author(s).


  • Almond hull
  • Cassava peel
  • Microfibrillated lignocellulose
  • Microwave hydrothermal

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