Facile self-assembly synthesis of titanate/Fe3O4 nanocomposites for the efficient removal of Pb2+ from aqueous systems

Abstract

We report a novel process for the self-assembly of Fe₃O₄ nanoparticles (NPs) onto titanate nanotubes (TNTs), nanofibers (TNFs) and nanosheets (TNSs) to synthesize magnetic titanate nanocomposites. Both coulombic and van der Waals forces made important contributions to control the assembly process, in which the Fe₃O₄ NPs were uniformly dispersed onto the surfaces of the titanate nanostructures by a facile acid-induced method. The Fe₃O₄ NPs possessed unique magnetic properties for adsorbent separation, while the structures of the titanates determined the efficiency of Pb²⁺ removal. Interestingly, it was found that Pb²⁺ can be completely and quickly removed by the TNTs/Fe₃O₄ and TNSs/Fe₃O₄ nanocomposites. It is worth noting that the TNTs/Fe₃O₄ nanocomposite possessed the maximum adsorption capacity of 382.3 mg g⁻¹, displaying a high efficiency for Pb²⁺ removal. The effects of pH value and contact time at different initial Pb²⁺ concentrations have been investigated. Based on the characterization results of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, a possible removal mechanism was proposed. This work provides a facile and general approach to synthesize magnetic functional nanocomposites for water treatment.