Synthesis and characterization of coated zero-valent iron nanoparticles and their application for the removal of aqueous Pb2+ ions

摘要

Three types of coated nanoscale zero-valent iron (C-nZVI) with different coatings, agar, starch, and carboxyl methyl cellulose, were synthesized using a rheological phase reaction method. The structure and morphology of C-nZVI particles were characterized by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. Batch tests of Pb(II) removal showed that the sample dosage, initial pH, initial Pb(II) concentration, and reaction time have significant effects on Pb(II) removal efficiency. Experimental results proved that an optimized pH value of 5, Pb(II) concentration of 100 mg/L, and C-nZVI dosage of 1 g/L are beneficial to Pb(II) removal. Kinetic study revealed that Pb(II) removal by C-nZVI in aqueous solution complies with quasi-first-order reaction kinetics, and the reaction rate constant of Pb(II) removal using W-nZVI is 6-27 higher than using unwrapped nZVI.