X. Wei, S. Bhojappa, L.-S. Lin, R.C. Viadero
selenium, magnetite nanoparticles, adsorption isotherm, adsorption thermodynamics
Selenium (Se) is an emerging contaminant for many regions worldwide especially for areas impacted by past or current mining activities. The objective of this study was to evaluate the effectiveness of synthesized magnetite nanoparticles as an adsorbent in removing Se from aqueous solutions. In this study, a series of batch adsorption experiments were conducted to study adsorption kinetics, isotherms, and adsorptive thermodynamics in conjunction with studies on the effects of pH, temperature, concentration, contact time, and presence of competing anions on Se removal efficiency. As opposed to either natural magnetite (<5µm) or nano-iron (~10 nm), magnetite nanoparticles(10-20 nm) were found to be a better adsorbent for selenite, while nano-iron showed better adsorption performance for selenate (Figure 1). A final concentration of < 5 µg-Se/L could be achieved in removing selenite using magnetite nanoparticles from initial Se concentrations of 100 µg-Se/L or lower, comparable to those commonly found in mine water or mining impacted streams. The selective Se adsorption demonstrated magnetite nanoparticles could be a very promising nano-sorbent in treating Se laden waters and wastewaters.