Evaluating the Role of Hydrochars as Sustainable Adsorbents for Pollutant Removal

Hydrothermal carbonization (HTC) produces biomass-derived hydrochar, a promising adsorbent for environmental remediation. Lignocellulosic biomass serves as the primary feedstock, and adsorption performance depends on biomass structure and HTC conditions, especially carbonization temperature. This review highlights hydrochar’s adsorption capabilities and modification strategies, including physical treatments to increase surface area and chemical treatments to introduce oxygen-containing functional groups. Heteroatom doping and acid-base modifications notably enhance the removal of metal ions and dyes. Hydrothermal treatment is key to producing tailored hydrochars for specific applications. Future research should focus on combining physico-chemical modifications, deepening understanding of adsorption mechanisms, and broadening hydrochar applications. These efforts will advance the use of biomass hydrochars as effective, sustainable adsorbents for pollution control while addressing waste management.