Fe Foam/Electroactivated Peroxydisulfate: A Highly Efficient Method to Remove Elemental Mercury

The removal of elemental mercury (Hg0) from simulated flue gas using the method of Fe foam/electroactivated peroxydisulfate (EA PDS) was carried out in an electrocatalytic reactor. Various factors including the voltage level, PDS concentration, temperature, electrolyte, initial pH, NO, and SO2 were considered to obtain optimized experimental parameters. It was found that approximately 95% of Hg0 was removed under optimal conditions: a voltage of 3 V, 2 mM of PDS, a reaction temperature of 20 °C, and pH = 7. NO would enhance the EA performance, while SO2 slightly inhibited the Hg0 removal activity. In addition, the stability of the Fe foam electrode was confirmed by a long-term experiment and indicated that the Fe foam electrode is efficient. The electrical energy consumption in the Fe foam/EA PDS system for Hg0 oxidation was estimated to be low. Meanwhile, scanning electron microscopy, energy-dispersive spectrometry, and X-ray diffraction obviously revealed the consumption of Fe foam and the production of Fe3O4. Scavenger experiments identified that SO4•– and •OH were the main reactive radicals. Based on characterizations and experiments, the pathway and mechanism for enhanced Hg0 removal were proposed.