Hydrothermally sulfonated single-walled carbon nanohorns for use as solid catalysts in biodiesel production by esterification of palmitic acid

- Carbon nanomaterials were prepared as acid catalysts by sulfonation reaction.
- Single-walled carbon nanohorns (SWCNHs) have great effect from sulfonation.
- Sulfonation effects on morphology and acidity of carbon-based catalysts.
- SWCNHs show high performance in esterification of palmitic acid.