Preparation of Halloysite/Ag2 O Nanomaterials and Their Performance for Iodide Adsorption

Abstract

Halloysite/Ag2 O (Hal/Ag2 O) nanomaterials were prepared by growing Ag2 O nanoparticles on the surface of nanotubular halloysite using silver nitrate solution under alkaline conditions. The nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption. Good dispersion of Ag2 O nanoparticles with average sizes of 6.07 ± 2.5 nm and 8.04 ± 3.8 nm was achieved in the nanomaterials when using different concentrations of alkali. The nanomaterial with 6.36% Ag2 O (Hal/Ag2 O-2) exhibited rapid adsorption to iodide (I−); adsorption equilibrium can be reached within 100 min. The adsorption capacity of I− on Hal/Ag2 O-2 is 57.5 mg/g, which is more than 143 times higher than that of halloysite. The nanomaterial also showed a better adsorption capacity per unit mass of Ag2 O due to the better dispersion and less coaggregation of Ag2 O in the nanomaterial than in the pure Ag2 O nanoparticles. Importantly, Hal/Ag2 O-2 exhibited high selectivity for I−, and its I− removal efficiency was hardly affected by the coexistence of Cl−, Br−, or SO42−, as well as the initial pH of the solution. With an excellent adsorption performance, the prepared Hal/Ag2 O nanomaterial could be a new and efficient adsorbent capable of the adsorption of radioactive I− from aqueous solution.