Removal of cobalt (II) by dithizone-immobilized nickel slag

In this study, activated nickel slag waste was modified with dithizone to remove Co(II) metal ions in the water. Dithizone was confirmed to have successfully been immobilized on an activated nickel slag using SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-ray), FTIR (Fourier-Transform Infrared Spectroscopy), and XRD (X-ray Diffraction). Studies on the adsorption of Co(II) metal ions in water were conducted by varying the solution's pH, adsorption mass, contact time, and Co(II) ion solution concentration. The findings revealed that the optimum pH conditions for adsorption occurred at pH 5 for 120 min and the adsorption kinetics followed a pseudo-second-order kinetics model. Meanwhile, the Langmuir isotherm model was used for Co(II) ion adsorption. The desorption study revealed that ion exchange interactions dominate activated nickel slag while hydrogen bonding and electrostatic interactions dominate nickel slag immobilized with dithizone.