The successive removal of Pb2+ and Congo red (CR) from aqueous solution by three magnetic phosphate nanocomposites (Fe3O4@Sr5(PO4)3(OH), Fe3O4@Ba3(PO4)2, and Fe3O4@Sr5xBa3x(PO4)3(OH), denominated FSP, FBP, and FSBP, respectively) was systematically investigated in comparison with Fe3O4 (denominated F) nanoparticle. FSP, FSBP, F, and FBP exhibited a high removal capacity of 351, 272, 76, and 23 mg/g for Pb2+, respectively. These materials could be reclaimed by magnetic separation and then used for successive CR remediation, showing a high CR removal capacity of 224, 163, 126, and 61 mg/g, respectively. The isothermal and kinetic behavior fitted well with the Langmuir model and pseudo-second-order model, respectively. The successive removal mechanism by these magnetic phosphates was proposed to be the ion exchange between Pb2+ and Sr2+ in the lattice and then the loaded Pb2+ could contact with anionic dye CR to form precipitation on the surface of materials, inhibiting the leaching of Pb2+ ions from the reclaimed materials back into water. In addition, these materials showed good reusability and practical application. This study demonstrated the potential of these low cost phosphate nanocomposites as promising materials for successive removal of Pb2+ and CR from water.
Bibliographical noteFunding Information:
This work was financially supported by the Natural Science Foundation of China (Grant No. 51402153 ), the Natural Science Foundation of Jiangsu Province (Grant No. SBK2017020336 ), and the Fundamental Research Funds for the Central Universities (Grant No. KYZ201747 ).
© 2018 Elsevier B.V.
- Heavy metal
- Magnetic phosphate nanocomposites
- Successive removal
- Water treatment