Three dimensional flower-like magnetic polyethyleneimine@MoS2 composites for highly efficient removal of Cr(VI) and Pb(II) ions.

Magnetic Fe3O4 nanoparticles were coated by polyethyleneimine (PEI), and then Fe3O4@PEI was further modified with MoS2 by the hydrothermal method to fabricate 3D flower-like structured magnetic polyethyleneimine@MoS2 (MP@MoS2) composites, and the composites were served as efficient adsorbents to capture Cr(VI) and Pb(II) from aqueous solution. The effects of temperature, pH, shaking time and environmental conditions on adsorption performance of MP@MoS2 towards Cr(VI) and Pb(II) have been conducted by batch adsorption experiments. The prepared MP@MoS2 exhibited high adsorption capacities (192.30 mg/g for Cr(VI) at pH 3.0 and 256.41 mg/g for Pb(II) at pH 6.0) and the adsorption equilibrium could be achieved in a short time. Moreover, MP@MoS2 composites with high saturation magnetization could be simply separated under an external magnet. Combined experiments and spectral analysis, the underlying adsorption mechanism for Cr(VI) on MP@MoS2 was mainly attributed to the reduction of Cr(VI) to Cr(III), and the removal of Pb(II) was due to the complexation with sulfur groups and amino-groups. Consequently, the prepared 3D flower-like structured MP@MoS2 has a great potential for the practical application in removing Cr(VI) and Pb(II) from the aquatic environment.