The combination of KMnO4 with HMO for cyclic adsorption of heavy metal ions and regeneration of adsorbents

Abstract

In this experiment, three kinds of hydrous manganese dioxide (HMO) with different Zeta potentials were synthesized, and combined with KMnO4 for deep removal of Pb2+, Cd2+ and Ni2+. The competitive adsorption of three heavy metal ions was also investigated. The results indicated that the stronger the acidity, the higher the Zeta potential (-54.3) of the synthesized HMO. After regenerating HMO with acidic KMnO4 as eluent, the removal rates of Pb2+, Cd2+ and Ni2+ could still reach 79.25%, 80.13% and 60.43% after five cycles of adsorption. The promoting mechanism of KMnO4's effect on HMO was analyzed by SEM, TEM, EDS, FTIR, XRD, XPS, BET, and UV-vis. After absorbing heavy metal ions, HMO will release part of Mn (II), and the released Mn (II) reacts with KMnO4 to form a small amount of highly active in-situ HMO. The ‘HMO + KMnO4’ system can not only improve the removal rate of heavy metal ions by HMO, and reduce the amount of adsorbent, but also remove the released Mn (II). Because of its reproducibility, efficiency and simplicity, the research on water purification materials and technologies is of significance. HIGHLIGHTS A novel mesoporous δ-MnO2 nanoparticle with high Zeta potential, large specific surface area and high hydroxyl content was prepared.; Low cost, simple preparation and high adsorption capacity.; Competitive adsorption of heavy metal ions.; Regeneration and cyclic adsorption of adsorbents.; Adding KMnO4 can greatly improve the removal efficiency of heavy metals and remove the residual Mn (II) in the solution.;

Keywords

• competitive adsorption
• cyclic adsorption
• in-situ reaction
• regeneration
• water chemistry