Promotion effects of potassium permanganate on removal of Pb(II), Ni(II) and Cd(II) from hydrous manganese dioxide

Surface properties of Hydrous manganese dioxide (HMO) can be described by Zeta potential (ZP), which is used to determine the performance of Pb(II), Ni(II) and Cd(II) removal. HMO with the highest ZP value (-51 mV) has been proved to have superior heavy metals removal ability. A novel discovery is that KMnO4 can facilitate HMO removing heavy metal. The results showed that residual Pb(II), Ni(II) and Cd(II) in pH similar to 8 were 0.01 mg/L, 0.02 mg/L and 0.05 mg/L after depth reaction, respectively. The mechanism of oxidation of Pb(II) in alkaline solution by KMnO4 with HMO catalyst was studied. The XPS results demonstrated that HMO improved oxidation efficiency of KMnO4 and the products Pb(IV) content increased by 50 percent approximately. The mechanism of Ni(II) removal was similar to Pb(II). Cd(II) could be absorbed but not be oxidized, while KMnO4 accelerated Cd (II) removal effect of HMO as well. KMnO4 promotion was still existing in the acidic conditions, which showed KMnO4 could promote HMO adsorption of heavy metal, and reaction mechanism is required for further study.