Synthesis and Application of Modified Zero-Valent Iron Nanoparticles for Removal of Hexavalent Chromium from Wastewater

Abstract

Zero-valent iron nanoparticles (nZVI) modified with sodium dodecyl sulfate (SDS) as an anionic surfactant were successfully synthesized and applied to Cr (VI) removal. The prepared nanoparticles were characterized by field emission scanning electron microscope (FSEM), energy-dispersive spectrometry (EDS), and Fourier transform infrared spectrophotometer (FT-IR). Meanwhile, the surface charges of the stabilized nanoparticles were also determined. In this study, the kinetics of particle aggregation and sedimentation were investigated. It was found that the modified nanoparticles had great stabilization. Effects of pH, contact time, dosage of nanoparticles, and initial Cr(VI) concentrations on removal efficiency of the heavy metal ions were investigated and optimized. The maximum removal efficiency of Cr(VI) was obtained at pH 3.0 and 25 °C, at the value of 98.919 %. Cr(VI) removal occurred fast, and achieved equilibrium after 120 min. The maximum removal capacity reached up to 253.68 mg g−1 dry nanoparticles at a 300-mg L−1 Cr(VI)-containing sample. Kinetics study showed a rapid removal dynamics fitting pseudo-second-order kinetic model. The equilibrium data was nicely fit to the Freundlich model and indicates the adsorption of Cr(VI) was highly favorable. The obtained results indicated that nZVI modified by SDS could be used as an efficient alternative for removal of heavy metals with enhanced removal capacity and application stability.