Ultrafine α-Fe2O3 nanoparticles grown in confinement of in situ self-formed “cage” and their superior adsorption performance on arsenic(III)

Abstract

Without the addition of surfactants or templates, ultrafine alpha-Fe(2)O(3) nanoparticles were successfully synthesized by a solvent thermal process at low temperature. During the synthesis, in situ self-formed "cage" of crystallized NaCl confined the growth of alpha-Fe(2)O(3) nanoparticles in both the precipitation and solvent thermal processes, resulting in the creation of well-crystallized alpha-Fe(2)O(3) nanoparticles with an average particle size about 4-5 nm and a high-specific surface area of similar to 162 m(2)/g. High resolution TEM investigations provided clear evidences of the in situ self-formation of NaCl "cage" during the synthesis and its confinement effect on the growth of alpha-Fe(2)O(3) nanoparticles. The superior performance of these alpha-Fe(2)O(3) nanoparticles on the adsorption of arsenite(III) (As) from aqueous environment was demonstrated with both lab-prepared and natural water samples at near neutral pH environment when compared with previously reported removal effects of As(III) by Fe(2)O(3). This unique approach may also be utilized in the synthesis of other ultrafine metal oxide nanoparticles for a broad range of technical applications.