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

[Display omitted] •Loading the MnO2 nanosheet on the fibers could avoid agglomeration.•The Fe3O4 fibers carrier made the absorbent magnetic separation rapidly.•The maximum adsorption capacity was very high among MnO2 based Pb(II) adsorbents.•The adsorbent exhibited Pb(II) treated capacity of ~6500 kg wastewater/kg sorbent.•The adsorption efficiency remained 83% after six adsorption cycles. 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.