Application of manganese nodules leaching residue for adsorption of nickel(II) ions from aqueous solution

Deep ocean manganese nodules are significant futuristic resource of copper, nickel and cobalt. After recovery of these valuable metals, a huge quantity of residue (~70 % of ore body) is generated. In the present paper, investigations carried out for the application of washed manganese nodule leaching residue (wMNR) for the removal of nickel (Ni) ions from aqueous solution by adsorption are described. Several parameters have been varied to study the feasibility of using wMNR as potential adsorbent for remediation of Ni(II)-contaminated water. The adsorption kinetics followed pseudo-first-order equation, and the rate of adsorption increased with solution temperature. Kinetics data of Ni(II) adsorption were also discussed using diffusion models of Webber–Morris and Dumwald–Wagner models. The equilibrium data were best fitted into Langmuir adsorption isotherm, and the maximum adsorption capacity was found to be 15.15 mg g^-1 at pH 5.5 and temperature 303 K, which decreased to 10.64 mg g^-1 upon raising the solution temperature to 323 K. The activation energy for Ni(II) adsorption onto wMNR was 9.56 kJ mol^-1 indicated physical sorption. Desorption studies showed successful regeneration of adsorbent and recovery of Ni. This process can be utilized for removal and recovery of Ni from the industrial effluent.

Keywords
Adsorption; Manganese nodule leached residue; Heavy metals; Nickel; Diffusion