Ferrate(VI): A green molecule in odorous gas treatment

The odorous gaseous emissions from industrial and wastewater treatment plant processes pose risk for natural ecosystem and human health. This chapter presents an assessment of the potential of ferrate(VI) (Fe^VIO₄^2-, Fe(VI)) to remove gaseous odor. Organosulfur compounds are usually predominate constituents of the odor and the kinetics, stoichiometry, and products of their oxidation by Fe(VI) is summarized. The second-order rate constants, k, of the oxidation reactions under alkaline conditions were in the range of ∼ 10¹ - 10⁵ M^-1s^-1. At a 10 mg L^-1 K₂FeO₄ dose, half-lives of the oxidation reaction would be in seconds or less at pH 9.0. The stoichiometry of the reactions of Fe(VI) with sulfur compounds generally varied from 1:2 to 2:3 and Fe(II) and Fe(III) were the reduced products of Fe(VI). Oxygen-containing products of the sulfur compounds were formed. Examples of case studies showed the efficient removal of odorous gases by Fe(VI).