Effect of temperature on air-water transfer of hydrogen sulfide

The extent of hydrogen sulfide transfer across the air-water interface plays a major role for odor and corrosion problems in sewer networks. One significant physical factor affecting the air-water transfer process is temperature. This study describes the temperature dependence of air-water transfer of hydrogen sulfide in terms of a temperature correction factor (temperature coefficient). The air-water transfer rate was found to increase with increasing temperature at a constant turbulence level. A mathematical expression for the transfer rate versus temperature was addressed following the Arrhenius equation. The temperature coefficient for air-water transfer of hydrogen sulfide was observed under acidic and neutral conditions (pH 4.5, 6.5, and 7.0), i.e., under conditions where only the molecular form of hydrogen sulfide was present (pH 4.5) and under conditions where both the molecular form and the ionized. form existed (pH 6.5 and 7.0). The effect of temperature on air-water transfer of hydrogen sulfide decreased with increasing pH. The temperature coefficients found in this study were within the range reported in the literature for other substances transferring across the air-water interface such as oxygen, ozone, and krypton-85.