[Removal of Fe(Ⅱ), Mn(Ⅱ), and NH 4 + -N by Using δ -MnO 2 Coated Zeolite].

δ -MnO ₂ /zeolite nanocomposites were prepared with natural zeolite, potassium permanganate, and manganese sulfate by oxidation-reduction precipitation, which were used to simultaneously remove Fe ²⁺ , Mn ²⁺ , and NH ₄ ⁺ -N from groundwater. To investigate the performance and mechanism of Fe ²⁺ , Mn ²⁺ , and NH ₄ ⁺ -N removal from groundwater by δ -MnO ₂ /zeolite nanocomposites, static batch experiments were conducted under different environmental conditions in a zero-oxygen atmosphere using SEM, TEM, Zeta potential, FTIR, and XPS techniques. The experimental results showed that the manganese-oxide-coated natural zeolite was δ -MnO ₂ , and Fe ²⁺ , Mn ²⁺ , and NH ₄ ⁺ -N adsorption on the δ -MnO ₂ /zeolite nanocomposites could be best described with the pseudo-second-order kinetic model and the Langmuir model. In addition, the maximum adsorption capacities of Fe ²⁺ , Mn ²⁺ , and NH ₄ ⁺ -N were calculated to be 215.1, 23.6, and 7.64 mg·g ^-1 , respectively. The removal mechanism of NH ₄ ⁺ -N from the solutions by zeolite was via the action of ion exchange, and the adsorption and oxidation catalysis of δ -MnO ₂ -coated zeolite were responsible for the removal of Fe ²⁺ and Mn ²⁺ . This research indicates that δ -MnO ₂ /zeolite nanocomposites could be used as highly efficient adsorbents to simultaneously remove Fe ²⁺ , Mn ²⁺ , and NH ₄ ⁺ -N from water.