Decontamination of sulfur contaminants from a vessel

1. A method for removing hydrogen sulfide, comprising:

(A) introducing a methylmorpholine-N-oxide solution to a vessel, wherein the vessel comprises a water layer and a gas layer, wherein the water layer and the gas layer comprise the hydrogen sulfide;

(B) introducing methylmorpholine-N-oxide into the water layer;

(C) treating the water layer by allowing the methylmorpholine-N-oxide to react with the hydrogen sulfide; and

(D) adjusting a hydrogen sulfide rate of condensation by reducing a vessel temperature.

2. The method of claim 1 , further comprising (E) treating the gas layer by allowing the hydrogen sulfide in the gas layer to react with the methylmorpholine-N-oxide.

3. The method of claim 1 , wherein the treating the water layer comprises converting the hydrogen sulfide to elemental sulfur.

4. The method of claim 3 , wherein the elemental sulfur is removed from the vessel.

5. The method of claim 1 , wherein the methylmorpholine-N-oxide comprises between about 0.01 weight volume % and about 60 weight volume % methylmorpholine-N-oxide of the water layer.

6. The method of claim 1 , wherein the methylmorpholine-N-oxide solution is introduced to the water layer in an amount to provide a mole ratio of methylmorpholine-N-oxide to hydrogen sulfide in the vessel from about 1.0 mole methylmorpholine-N-oxide: 1.0 mole hydrogen sulfide to 3.0 moles methylmorpholine-N-oxide: 1.0 mole hydrogen sulfide.

7. The method of claim 1 , further comprising introducing steam to the vessel.

8. The method of claim 7 , wherein the steam comprises 150 psig steam or less.

9. The method of claim 8 , further comprising introducing the steam to the vessel to increase the temperature of the water layer to a temperature from about 70° F. to about 150° F.

10. The method of claim 1 , wherein the water layer further comprises an iron oxide.

11. The method of claim 1 , wherein the water layer comprises from about 100 ppm iron oxide to about 1,000 ppm iron oxide.