Materials derived from a sulfur vulcanization of biochar

Area of Science:

• Materials Science
• Biomass Conversion
• Sustainable Chemistry

Background:

• Pyrolysis of lignocellulosic biomass produces biochar, a high-carbon material.
• Raw biochar is mechanically weak and unsuitable for structural applications.
• Enhancing biochar's mechanical strength and stability is crucial for its broader use.

Purpose of the Study:

• To improve the mechanical strength and chemical stability of biochar.
• To explore the use of elemental sulfur for biochar crosslinking.
• To develop sustainable structural materials from biomass.

Main Methods:

• A biochar-sulfur (BS) mixture was heated under pressure up to 185 °C.
• Elemental sulfur induced a vulcanization reaction, crosslinking the biochar's carbon network.
• Free-radical sulfur polymerization and addition to functional groups were key reactions.

Main Results:

• The synthesis method significantly enhanced biochar's mechanical strength.
• Compressive strength reached up to 382.5 MPa and Young's modulus up to 165 GPa.
• Synthesized materials exhibit properties comparable to structural steel at a low density of 1.4 g cm⁻³.

Conclusions:

• Crosslinked biochar-sulfur materials demonstrate remarkable mechanical properties.
• These materials offer potential for sustainable infrastructure and transport applications.
• The method also presents a pathway for biomass-derived carbon storage and climate change mitigation.