Selenium functionalized magnetic nanocomposite as an effective mercury (II) ion scavenger from environmental water and industrial wastewater samples

A novel core-shell magnetic-selenium nanocomposite (Fe3O4@SiO2@Se) was synthesized for fast and effective removal of Hg (II) ions from various industrial and environmental water samples. The composition, property, and structure of Fe3O4@SiO2@Se were characterized by spectral and microscopic techniques. The key parameters affecting the removal were evaluated and optimized. The concentration of residual Hg (II) ions in the solution was measured using a cold vapor atomic absorption spectrometer. At pH = 3.0, Fe3O4@SiO2@Se was capable to remove Hg (II) ions ranged from 100 mu g L-1 to 10 mg L-1 within 20 min with the efficiency of approximately 99% in a way that residual concentration levels matched international standards. This level of removal efficiency was well maintained up to salinity of 25 g L-1. Kinetic investigations revealed compliance with a second-order kinetic model. The linear regression coefficient suggested the adsorption of Hg (II) ions by the adsorbent followed the Langmuir isotherm model (R-2 > 0.997). The maximum capacity of the adsorbent obtained through investigating the isotherms was 70.42 mg g(-1). The Fe3O4@SiO2@Se adsorbent effectively removed the Hg (II) ions spiked to different samples, including tap water, river water, seawater, and industrial wastewater. Therefore, this nano-adsorbent can be used as a good alternative for Hg (II) removal, in practical applications.