Synthesis and characterization of sargassum-based hydrochar for the removal of emerging contaminants in aqueous media

Abstract Water pollution from industrial dyes represents a serious environmental challenge. This study addresses the problem by valorizing Sargassum, a macroalgae that generates serious ecological and economic issues in the Mexican Caribbean. A hydrochar was synthesized from Sargassum spp biomass by hydrothermal carbonization (240 °C, 5 h) with chemical activation with KOH. The hydrochar was characterized by FTIR spectroscopy and scanning electron microscopy. The results show the chemical bonds, structure, and morphology of this carbonaceous material. Hydrochar was tested as an adsorbent for the removal of methylene blue and rhodamine B. The results showed a high affinity for methylene blue, with a maximum adsorption capacity of 52 ± 11 mg/g, typical of mesoporous materials. Adsorption was considerably lower for rhodamine B, a larger molecule, suggesting a molecular-size-exclusion mechanism. This work demonstrates that Sargassum spp. can be converted into an economical and efficient adsorbent for wastewater treatment. Graphical abstract