Removal of cobalt ions from waste water by Friedel's salt

In this study, the adsorption behaviors of the Friedel's salt for Co(II) from aqueous solution at different concentrations and various initial pHs are investigated. The adsorption process follows the pseudo-second-order model and can be described by the Langmuir adsorption isotherm. The experimental results demonstrate that Friedel's salt has a high Co (II) adsorption (up to capacity 3.682 mmol Co(II)/g) and a strong adsorption efficiency (>99.98% Co(II) adsorption at [Co] < 16.00 mM with 4.0 g L-1 of adsorbent). Due to isomorphic substitution behavior, less than 0.2% Co(II) will be leached from the newly formed Co-adsorbed hydrocalumite during the ions stability tests. The present study reveals that Friedel's salt could be applied as a low cost and high efficiency adsorbent for the removal of cobalt from waste water.