Nanomaterials | Hydrolysis of Plant Waste

The worldwide cultivation of economic crops becomes more and more pronounced with a significant rate of growth year by year. These plants, however, do not only provide useful material, but also huge amounts of residues.


Magnetic carbonaceous acids were synthesized by pyrolysis of homogeneous mixtures of glucose and magnetic Fe3O4 nanoparticles with subsequent sulfonation.

The synthesis conditions were optimized to obtain a catalyst with high acid density and strong magnetism. Ball-milled cellulose was used as model material in order to evaluate the optimum hydrolysis conditions in terms of microwave heating
(temperature, time), substrate/weight ratio, and solvent/weight ratio.

With the optimized conditions at hand the catalyst was successfully applied to original plant wastes. Hydrolysis of tropical biomass resulted in high yields of total reducing sugar (TRS) and glucose:

80% and 58% for bagasse, 47% and 36% for Jatropha hulls, and 54% and
36% for Plukenetia hulls.

Key findings

  • Microwave-assisted heating
    Elevated temperatures are easily achieved with a Monowave reactor.Reaction time could be reduced from 24 h to 3.5 h.
  • Efficient hydrolysis of plant waste
    Bagasse, Jatropha and Plukenetia plants could be hydrolyzed with high TRS and glucose yields. Prior removal of fatty acids and phenols (via extraction) increases the hydrolysis yields.
  • Reusable catalyst
    Due to its magnetic properties the catalyst can be easily separated. The catalyst works efficiently in at least 7 cycles.

Good to know

Reaction Conditions

Hydrolysis Procedure:
- Monowave reactor with G30 vials
- 27 mg biomass
- 150 mg magnetic sulfonated catalyst
- 11.25 mL water
- 190 °C for 3.5 h 

Further reading:
- T.-C. Su et al., Sci. Rep. 2015, 5, 17538, doi: 10.1038/srep17538

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