Study of the catalytic iron oxidation of hydrogen sulfide by air oxygen in a reactor with a membrane separator

Summary

The results of studies of the catalytic iron oxidation of hydrogen sulfide by air oxygen in a reactor with a membrane separator are presented. The studies were carried out in a laboratory setup. An artificially prepared model hydrogen sulfide-containing water served as the object of study. The laboratory setup was a reactor vessel where hydrogen sulfide was oxidized by air oxygen in the presence of iron hydroxide that acted as a catalyst for the process. The separation of purified water and Fe (OH)₃ was carried out by ultrafiltration. All the experiments were executed under the conditions recommended for the iron catalytic oxidation of hydrogen sulfide: concentration of iron (III) hydroxide 2 g/dm₃, pH 7–8, residence time in the reactor 1 hour, air consumption 2 m³/m³, temperature 20–23 ºС. The oxidizing ability of the method has been experimentally confirmed at the above standard values of the indicators. A regression equation has been obtained that describes the catalytic oxidation of hydrogen sulfide by air oxygen in a reactor with a membrane separator. The presented method can be recommended in the process flow schemes of natural hydrogen sulfide-containing water purification for the purposes of drinking water supply.

Key words

ultrafiltration , sulfide-alkaline wastewater , hydrogen sulfide , membrane separation , air oxygen , iron hydroxide

Removing hydrogen sulfide from water with air oxygen
by the method of «dry» filtration in anthracite media

Summary

One of the causes that limit the widespread use of artesian waters is the presence of hydrogen sulfide. The method of removing hydrogen sulfide from water by converting the ionic forms HS^- and S^2- into molecular H₂S (acidification of water to pH ≤ 5) with subsequent degassing is not environmentally friendly due to air pollution with hydrogen sulfide blown away in the degasser. Oxidation of hydrogen sulfide to elemental sulfur or its oxides is carried out with the use of expensive oxidants that while being applied require special safety measures. An effective chemical free method of removing hydrogen sulfide from water can be the use of an oxidizing filter consisting of a sealed housing partially filled with non-submerged catalytic electrically conductive anthracite media with a grain size of 0.8–2 mm. Air is injected into the distribution perforated water feeding system located above the media. Herewith, the tightness of the filter eliminates the emission of hydrogen sulfide into the atmosphere and pollution of the room, whereas the entire volume of the catalytic media is residing in an oxygen-containing environment in the most active mode of catalytic oxidation of hydrogen sulfide. Purified water is collected at the bottom of the filter in a collector with an air outlet connected to it. After 2–4 days of operation, the filter is removed from the filtration mode to regenerate the catalytic media by back air washing with the removal of elemental sulfur S⁰ formed during the oxidation of hydrogen sulfide.

Key words

liquid-phase oxidation , «dry» filtration , hydrogen sulfide-containing underground water , anthracite filtering media , air oxygen