Absorption of H2S in NaOCl caustic aqueous solution

Pilot plant experimental data were collected to study the feasibility of H2S removal from air streams utilizing aqueous solutions. Solutions of NaOCl/NaOH were tested in a packed bed scrubber and found to be effective. An efficiency of 99.2% H2S removal was achieved at a gas flow rate of 790 lb/f2 ‐hr and liquid‐gas ratio of 5.06. Sodium hydroxide was found to be the active ingredient in the absorption process. A minimum alkalinity of pH 11 in the scrubbing solution was required for the H2S to be efficiently absorbed in the packed bed scrubber. For gas flow rates up to 2,100 lb/f2 hr, the height of a transfer unit (HTU) varied from 1.8 ft to 2 ft with different proportions of NaOCl and NaOH in the solution.