High saturation magnetization MnO₂/PDA/Fe₃O₄ fibers for efficient Pb(II) adsorption and rapid magnetic separation

The functionalized MnO₂/PDA/Fe₃O₄ fibers were synthesized to removal Pb(II) from wastewater. MnO₂ nanosheets were in-situ loaded on the high saturation magnetization Fe₃O₄ fibers matrix through a polydopamine (PDA) intermediate platform. The high Fe₃O₄ content enabled the composite fibers to achieve rapid magnetic separation. The perpendicularly orientated MnO₂ nanosheets coated on the fibers could avoid agglomeration and give full play to their outstanding adsorption performance. The maximum Pb(II) adsorption capacity at 300 K, 308 K and 318 K calculated by Langmuir model could reach 196.67, 200.45 and 205.07 mg/g, respectively; all of which were higher than those of most reported MnO₂ based adsorbents. Thermodynamics showed that the fibers had spontaneously physicochemical adsorption of Pb(II). The composite fibers adsorbents had excellent Pb(II) selective adsorption and reusability. In addition, under the laboratory simulation test conditions, the fibers exhibited an excellent Pb(II) treated capacity of ~2500 and 6500 kg wastewater per kg adsorbents. This could dramatically purify wastewater from 10 mg/L to below 0.01 mg/L and 0.1 mg/L. The prepared MnO₂/PDA/Fe₃O₄ fibers had excellent adsorption capacity and actual treated capability for Pb(II), which could bring about rapid magnetic separation and offer great application potential in Pb(II) adsorption removal.