Valorization of tree leaves waste using microwave-assisted hydrothermal carbonization process

Kang Kang, Tianle Zhang, Guotao Sun, Mingqiang Zhu, Kankan Li, Dongbing Li

Research output: Journal PublicationArticlepeer-review

5 Citations (Scopus)


Fallen leaves of landscape trees, as an emerging biomass waste, were valorized using conventional hydrothermal carbonization (HC) and microwave-assisted hydrothermal carbonization (MHC) pretreatments, and were comparatively characterized for physicochemical properties and thermal degradation kinetics. The results show that MHC is superior to conventional HC operation, because at 200℃, the MHC process not only gives a higher hydrochar yield (45.09 vs. 39.47 wt%) with significantly reduced energy consumption (0.63 vs. 2.74 MJ g−1), but also is more effective in removing K and Si. For isoconversional kinetic analysis, the FWO method provides better results than the KAS method as the latter failed to fit the tree leaves sample (R2 < 0.9). The thermal degradation kinetics at high temperatures (>400℃) showed that the hydrochar obtained from the MHC process has a lower average activation energy of ~190 MJ kg−1 than the conventional HC process (~260 MJ kg−1). This study reveals the potential for valorization of the landscape tree wastes via the MHC process.

Original languageEnglish
Pages (from-to)1690-1703
Number of pages14
JournalGCB Bioenergy
Issue number10
Publication statusPublished - Oct 2021
Externally publishedYes


  • biomass
  • hydrochar
  • hydrothermal carbonization
  • isoconversional kinetic analysis
  • urban fallen leaves
  • valorization

ASJC Scopus subject areas

  • Forestry
  • Renewable Energy, Sustainability and the Environment
  • Agronomy and Crop Science
  • Waste Management and Disposal


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