Synthesis and application of manganese dioxide coated magnetite for removal of metal ions from aqueous solutions

Manganese dioxide with magnetic properties has been synthesized by precipitation of MnO2 in the presence of magnetite. The adsorbent is almost exclusively a cation exchanger although sorption of oxoanions is also possible. Sorption experiment with Cd2+, Ni2+, and Pb2+ ions revealed a preferred sorption. Alkaline earth ions such as Ca2+ affect the uptake only at high concentrations. Because of the small particles and the respective large specific surface, sorption is fast.