Carbon-containing bone hydroxyapatite obtained from tuna fish bone with high adsorption performance for Congo red

Abstract

The carbon-containing bone hydroxyapatite (CBHA) has been obtained from tuna fish bone in which the carbon derived from the organics inside the bones acts as a dispersant. The XRD and TEM results indicated that the obtained HA is on the nanoscale and the N₂ adsorption/desorption isotherm showed that CBHA has mesoporous structure with an enhanced specific surface area (1129.0 m² g⁻¹). Moreover, CBHA as an adsorbent for removal of Congo red (CR) from aqueous solution exhibited high adsorption capacity (329.0 mg g⁻¹) and the adsorption pattern fitted well with Langmuir model (R² > 0.96). The adsorption kinetics of CBHA for CR followed the pseudo-second-order model. Thermodynamic parameters, including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), indicated that the adsorption of CR onto CBHA was feasible, spontaneous, and endothermic at the temperature range of 303–323 K. Thus, CBHA as an efficient and low-cost adsorbent can be applied to the treatment of industrial effluents contaminated with CR.