Rapid removal of low concentration Hg(II) from water by iron nanoparticles: Excellent performance and unique mechanism

Mercury is highly toxic. It is a great threat to human health even with low-concentration mercury ingestion. Herein, we systematically explored the performances and mechanisms of nano zero-valent iron (nZVI) and sulfurized nano zero-valent iron (S-nZVI) for low concentration Hg(II). The S⁰ produced in the sulfidation process has a strong immobilization effect on Hg⁰ and reduces the volatilization of Hg⁰ into the air, which prevents secondary pollution. We discovered some unique mechanisms that occur only in the rapid treatment of low concentrations of mercury: the theory that sulfidation will inhibit the formation of FeOOH and thus enhance the reduction properties of S-nZVI was proposed for the first time; The formation of Fe(OH)_x is no longer able to promote adsorption and coprecipitation for Hg(II) but instead hinders reduction on Hg(II). These findings provide insights into the purification of water containing low concentrations of Hg(II) by iron nanoparticles.