Hydrothermal carbonization of pleco fish bones: Characterization and potential use as a fluoride adsorbent in water

Excessive fluoride levels in drinking water (> 1.5 mg L −1 ) pose a severe public health risk, necessitating the development of effective, sustainable water quality improvement methods. This study explored the use of pleco-fish bone hydrochar (HC) as a fluoride adsorbent. HC was produced via hydrothermal carbonization (210 °C for 6 h) and characterized. It exhibited increased specific surface area (43 to 113 m 2 g −1 ) and primarily consisted of Ca, P, C, and O, indicating hydroxyapatite presence. HC displayed a fluoride adsorption capacity of 4.68 mg g −1 at an initial 10 mg L −1 concentration, rising to 10 mg g −1 as the initial fluoride concentration increased from 2 to 60 mg L −1 . However, the removal percentage dropped from 87 to 36% due to HC saturation. These findings highlight HC’s potential as a promising adsorbent for fluoride removal from aqueous solutions, addressing a critical public health concern. Graphical abstract