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The Chemistry of H2S Mitigation. We capitalize on 3 important properties of the H2S molecule during the process of H2S mitigation.

H2S is an acidic gas and will salt many amines to the aminium hydrosulphide. The reaction is however reversible and forms the basis of an amine recycling unit; the salt being dissociated back to H2S and free amine by heat. This process does also remove CO2 since it is also an acidic gas.

H2S is a reducing agent and thus can be readily oxidized. The valence state of sulphur is -2 in H2S and can be oxidized to 0, elemental sulphur (e.g. alkaline sodium nitrite or hydrogen peroxide) or +6, sulphate by chlorine dioxide, hypohalites etc.

H2S is a powerful nucleophile due to the sulphur atom which is a soft Lewis base. The electrons are in the 3 electron shell, further from the nucleus, more mobile and easily displaced. A perfect example of this is the fact that H2O is a liquid with a boiling point of 100 C whereas H2S, a heavier molecule, is a gas with boiling point -60 C. The hard Lewis basic property of the oxygen atom forms very strong hydrogen bonds, more so than H2S, hence the huge boiling point difference. The nucleophilic potential of the sulphur atom is used in the reaction with triazine, formaldehyde and hemiformal or formaldehyde releasers, acrolein and glyoxal.