Here are brief descriptions of chemistries used to remove hydrogen sulfide (H2S) from water:

  1. Hydrogen Peroxide (H2O2): A strong oxidant that converts H2S to elemental sulfur or sulfate, depending on pH and dosage. It’s effective, environmentally friendly, and produces minimal byproducts. Reaction: H2S + H2O2 → S + 2H2O or H2S + 4H2O2 → H2SO4 + 4H2O.
  2. Chlorine-Based Oxidation (NaOCl or Cl2): Sodium hypochlorite or chlorine gas oxidizes H2S to sulfur or sulfate. It’s cost-effective but may form disinfection byproducts. Reaction: H2S + Cl2 → S + 2HCl.
  3. Ozone (O3): Ozone oxidizes H2S to sulfur or sulfate across a wide pH range. It’s effective without chlorinated byproducts but requires on-site generation. Reaction: H2S + O3 → S + H2O.
  4. Potassium Permanganate (KMnO4): Oxidizes H2S to sulfur or sulfate. It’s reliable but can leave a pink color if overdosed. Reaction: 3H2S + 2KMnO4 → 3S + 2MnO2 + 2H2O + 2KOH.
  5. Iron-Based Chemistries (FeCl3 or Fe2(SO4)3): Ferric chloride or sulfate precipitates H2S as iron sulfide (FeS), which is filtered out. Effective in low-oxygen settings. Reaction: Fe3+ + H2S → FeS + 2H+.
  6. Aeration (O2): Air or oxygen oxidizes H2S to sulfur or sulfate, best at high pH. It’s simple but slow for high H2S levels. Reaction: 2H2S + O2 → 2S + 2H2O.
  7. Nitrate Addition (NaNO3 or Ca(NO3)2): Nitrates enable bacteria to oxidize H2S to sulfate in anaerobic conditions, often used for odor control. Reaction: 5H2S + 8NO3- → 5SO42- + 4N2 + 4H2O + 2H+.
  8. Caustic Scrubbing (NaOH): Sodium hydroxide reacts with H2S to form sodium sulfide or hydrosulfide, typically used in gas-phase but adaptable for water. Reaction: H2S + NaOH → NaHS + H2O.

Selection depends on H2S concentration, water chemistry, and system scale.