A new strategy for selective recovery of low concentration cobalt ions from wastewater: Based on selective chelating precipitation-flotation process

Background: A significant amount of low-concentration heavy metal ion wastewater is generated daily by the mining and metallurgy industry, endangering human health and the environment. A novel method of selective chelating precipitation-floatation of copper and cobalt ions is proposed for the recovery of cobalt from wastewater.Methods: Based on the chelation of cobalt and copper ions with alpha-nitroso-beta-naphthol (NN), the flotation process is adopted to solve the problem of fine particle separation from solution in low-concentration ions removal.Significant findings: Under the optimized precipitation flotation conditions, the flotation recovery ratios of the copper, cobalt, and zinc ions were found to be 98.47%, 42.48%, and 9.35%, respectively, and the separation effect of cobalt and zinc showed to be outstanding, as their separation factor reached 598. Industrial wastewater also has a good flotation separation effect. Based on the mechanism studies, Co2+/Co3+ and Cu2+ were selec-tively chelated by NN to form hydrophobic NN-Co/Cu precipitation particles. Moreover, electrostatic attraction is the main force in the proposed flotation process. Eventually, we tried calcination to recycle the flotation products to verify the potential of the cobalt-copper composite oxides in capacitor materials. The results prove that the precipitation-flotation method has great efficiency and potential for selectively recovering low -concentration metal ions and separating fine particles from solution.

Automated summary

Selective chelating precipitation-floatation method shows high efficiency and potential in the recovery of low-concentration cobalt ions from wastewater and the separation of cobalt and zinc.