Study on the Adsorption Mechanism of Cobalt and Nickel in Manganese Sulfate by δ-MnO.

Manganese has excellent performance in removing metal ions from aqueous solutions, but there are few studies on the adsorption and removal of heavy metal impurities in metal salt solutions. In this paper, the adsorption of cobalt and nickel ions in MnSO solution by δ-MnO prepared from two different manganese sources was studied. The optimum adsorption conditions were as follows: When the concentration of Mn was 20 g/L, δ-MnO addition was 10 g/L, Co concentration was 80 mg/L, Ni concentration was 80 mg/L, reaction time was 60 min, reaction temperature was 80 °C, and pH value was 7, the adsorption rate of Co and Ni reached more than 80%.

Relationship between Surface Hydroxyl Complexation and Equi-Acidity Point pH of MnO and Its Adsorption for Co and Ni.

MnO has shown great potential in the field of adsorption and has a good adsorption effect on heavy metal ions in aqueous solution, but there have been problems in the adsorption of heavy metal ions in high-concentration metal salt solutions. In this paper, different crystal forms of MnO (α-MnO, β-MnO, γ-MnO, δ-MnO, δ-MnO, and ε-MnO) were prepared and characterized by XRD, SEM, EDS, XPS, ZETA, and FT-IR. The reasons for the equi-acidity point pH change of MnO and the complex mechanism of surface hydroxylation on metal ions were discussed.