Development of a Nanostructured α-MnO2/Carbon Paper Composite for Removal of Ni2+/Mn2+ Ions by Electrosorption

Toxic metal ions, such as Ni2+ and Mn2+, in industrial waste streams are nonbiodegradable and can cause damage to the human body. Electrochemical cleaning techniques are attractive as they offer more control and produce less sludge than do chemical/biological approaches without the high pressures needed for membranes. Here, nanoneedle-structured α-MnO2/carbon fiber paper (CFP) composites were synthesized by a hydrothermal approach and used as electrodes for combined electroadsorption and capacitive deionization removal of nickel and manganese ions from pseudoindustrial waste streams. The specific performance of α-MnO2/CFP (16.4 mg Ni2+ per g of active material) not only shows a great improvement in comparison with its original CFP substrate (0.034 Ni2+ mg per g), but also is over 6 times that of activated carbon (2.5 mg Ni2+ per g). The high performance of α-MnO2/CFP composites is attributed to their high surface area, desirable mesoporosity, pore-size distribution that permits the further access of ions,...