A method for solubilizing a carbonaceous feedstock. The method includes steps of reacting a mixture of the carbonaceous feedstock with a metal oxide including a metal at a first, higher oxidation state to reduce the metal of the metal oxide to a second, lower oxidation state by releasing at least one oxygen atom from the metal oxide. The released oxygen from the metal oxide is used to oxidize the carbonaceous feedstock. At least a portion of the metal or metal oxide containing the metal at the second, lower oxidation state is then oxidized to the metal oxide containing the metal at the first, higher oxidation state for reuse in the reaction step.

An oxidizing composition for removing hydrogen sulfide (H.sub.2S) from a gaseous or liquid stream includes mixture products of water, sodium hypochlorite, a chelating agent, and a transition metal compound. The chelating agent can be etidronic acid; the transition metal compound can be an iron (III) compound, such as ferric sulfate. The oxidizing composition is formed by (i) combining water, chelating agent, and transition metal compound to form an activator composition and (ii) mixing the activator composition with a sodium hypochlorite solution to adjust the pH, such as for a particular use. Some embodiments include various apparatuses and methods for treating different treatment sites with the oxidizing compositions disclosed herein. Examples of suitable treatment sites include, without limitation, natural gas pipelines, bubble towers, oil wells, gas wells, sewer wet wells, air scrubbers, saltwater disposal pipelines, and saltwater disposal wells.

An oxidizing composition for removing hydrogen sulfide (H.sub.2S) from a gaseous or liquid stream includes mixture products of water, sodium hypochlorite, a chelating agent, and a transition metal compound. The chelating agent can be etidronic acid; the transition metal compound can be an iron (III) compound, such as ferric sulfate. The oxidizing composition is formed by (i) combining water, chelating agent, and transition metal compound to form an activator composition and (ii) mixing the activator composition with a sodium hypochlorite solution to adjust the pH, such as for a particular use. Some embodiments include various apparatuses and methods for treating different treatment sites with the oxidizing compositions disclosed herein. Examples of suitable treatment sites include, without limitation, natural gas pipelines, bubble towers, oil wells, gas wells, sewer wet wells, air scrubbers, saltwater disposal pipelines, and saltwater disposal wells.