Performance of Nano-Magnetite for Removal of Selenium from Aqueous Solutions

摘要

Selenium (Se) is emerging as a contaminant that must be dealt with in many areas of the world, especially thosenareas impacted by past or current mining activities. In this study, we evaluate the effectiveness of synthesizednnano-magnetite when used as an adsorbent to remove anionic selenium species from aqueous solutions. Innconjunction with studies on the effects of pH, temperature, concentration, contact time, and presence of competingnanions on selenium removal efficiency, a series of batch adsorption experiments were conducted to studynadsorption isotherms and adsorptive thermodynamics. Compared with either natural magnetite ( < 5 lm) ornnano-iron (*10 nm), nano-magnetite (10–20 nm) was found to be a better adsorbent for selenite, while nano-ironnshowed better adsorption performance for selenate. From an initial selenium concentration of 100 lg-Se/L,nwhich is comparable to those commonly found in mine water or mining impacted streams, a final concentrationnof < 5 lg-Se/L could be achieved, using nano-magnetite. Low pH favored selenite adsorption, and elevatedntemperature enhanced selenium removal. Selenite adsorption followed the Freundlich isotherm model, and thenpresence of common anions did not significantly affect the adsorption capacity of nano-magnetite for selenite.nSelective adsorption demonstrated that nano-magnetite could be a very promising nano-sorbent to treat seleniumncontaminated water