Carbon microspheres decorated with iron sulfide nanoparticles for mercury(II) removal from water

A new and simple method is developed to synthesize carbon microspheres decorated with iron sulfide nanoparticles for mercury ion removal from water. The synthesis is based on carbonizing polystyrene-divinylbenzene-based and iron(III) sulfate-loaded cation exchange resins between 500 and 1000 degrees C. The phase composition, surface area, and morphology of these materials are characterized by various spectroscopic and diffraction techniques, including Mossbauer spectroscopy, powder X-ray diffraction, Raman and scanning electron microscopy, and BET analysis. Pyrrhotite is found to be the dominant iron-containing phase. The adsorption performance of microspheres for mercury ion removal from water is studied as a function of adsorbent load and contact time at pH 6.5 using a solution of 40 mg dm(-3) mercury ion. Pyrrhotite nanoparticles played a key role in mercury ion removal amounting to 70-90% of the extracted amount. A high adsorption capacity of 104 mg of mercury/g of adsorbent at an adsorbent load of 0.33 g dm(-3) is achieved, and the removal kinetics could be well fitted with a pseudo-second-order kinetic model, indicating chemical sorption. The synthetic method is easy to scale up for large-scale production and materials are easy to handle, which is significant for large-scale environmental applications.