Preparation of Pyridinium-Functionalized Magnetic Adsorbent and Its Application for Nitrate Removal from Aqueous Solution

Abstract

A novel magnetic pyridinium-functionalized mesoporous silica adsorbent (Fe 3 O 4 @SiO 2 @Py-Cl) was synthesized for nitrate removal from aqueous solutions. The adsorption performances were investigated by varying experimental conditions such as pH, contact time, and initial concentration. The adsorbent was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and magnetic hysteresis loops. The results showed that the adsorption equilibrium could be reached within 30 min and the kinetic data were fitted well by pseudo-second-order and intraparticle diffusion model. The adsorbent exhibited a favorable performance, and its maximum adsorption capacity calculated by the Langmuir isotherm model was 1.755 mmol/g. The nitrate adsorption mechanism was mainly controlled by the material through ion exchange of nitrate with chloridion, as determined by XPS. This study indicated that this novel pyridinium-functionalized mesoporous material had excellent adsorption capacity. Meanwhile, compared with other adsorbents, it could remove nitrate fast and easy to be collected by magnetic separation, showing great potential application for nitrate removal from aqueous solution.