Efficient and rapid removal of Pb2+ from water by magnetic Fe3O4@MnO2 core-shell nanoflower attached to carbon microtube: Adsorption behavior and process study

Abstract Designing highly efficient, recyclable and environmentally friendly adsorbent for the removal of heavy metal ions from wastewater plays a key role in sewage treatment system. In this study, a magnetic Fe3O4@MnO2 core-shell nanoflower attached to Aspergillus niger carbon microtube was developed as a perfect adsorbent for the removal of Pb2+ from water solution. Benefiting from the synergistic effect of high adsorption capacity of metal oxides, magnetism of Fe3O4 and large size of Aspergillus niger carbon, the synthesized adsorbent achieves an extremely high adsorption capacity of 934 mg/g and a faster adsorption speed of 5 min, which is a splendid performance among reported adsorbent of Pb2+ from water solution. Supported by FTIR spectra, a large amount of carbon dioxide and hydroxyl groups were proved to exist on the surface of the Fe3O4@MnO2/CT, where the functional groups with negative charges play a key role in facilitating the interface adsorption process. Moreover, the amorphous magnetically adsorbent with a size of about 300 nm have a specific surface area of 151 m2/g and the high saturation magnetization of the adsorbent is highly beneficial to the re-recovery of the adsorbent. After five cycles of testing, the adsorbent can still guarantee a maximum saturated adsorption capacity of more than 86%. The lead element is adsorbed on the surface of the adsorbent in the form of basic lead carbonate, which suggests that the basic adsorption mechanism is chemical adsorption.