Efficient removal of Hg²⁺ in aqueous solution with fishbone charcoal as adsorbent

The Hg²⁺ removal performance of fishbone charcoal prepared from discarded fishbone has been investigated in this work. The XRD, FTIR, and BET results demonstrated that the main composition of fishbone charcoal was hydroxyapatite and the specific surface area was 117 m²/g. The adsorption experiments indicated that fishbone charcoal had an extremely high adsorption capacity for Hg²⁺ (243.77 mg/g). The excellent Hg²⁺ adsorption capacity might be ascribed to the ion exchange of Hg²⁺ to the Ca²⁺ in the structure of fishbone charcoal, complexation of Hg²⁺ with ≡Ca(OH)²⁺ on the surface of fishbone charcoal, as well as electrostatic interaction between electronegative fishbone charcoal surface and cation Hg²⁺. This work transformed kitchen garbage (i.e., fishbone) into an effective mercury adsorbent with considerable capacity, giving a perspective sight for the utilization of solid waste.