Production of hydroxyapatite‐based adsorbent for the removal of cobalt ions from the aqueous solution

Abstract The aim of the current study was to recover and separate cobalt ions from multielement solution, using hydroxyapatite (HAp) and magnetic nanocomposite of HAp/Fe 3 O 4 as adsorbents. Cobalt ion adsorption process was conducted batchwise within the temperature 25˗55°C, exposure duration 5˗120 min by applying a dose of 0.25–5 g/L as the adsorbent at pH 2 to 9. Adsorbent characterization was performed using advanced spectroscopic techniques such as Fourier Transform Infrared Spectroscopy, Scanning electron microscopy, and Energy‐dispersive X‐ray spectroscopy. The maximum ionic adsorption efficiency using HAp was 90.48% against 94.72% in the case of the magnetic nanocomposite of HAp, under optimal conditions. Various isotherm models were used to evaluate the adsorption capacity and equilibrium coefficients for adsorption of the cobalt ions by the prepared adsorbents. The isotherm models data showed that the adsorption process is desirable by the adsorbents and by adding nanoparticles of Fe 3 O 4 the adsorption capacity improves.