Novel sensor based on Ag/Ag2S electrode for in situ measurement of dissolved H2S in high temperature and pressure fluids

This H2S sensor, constructed from an Ag/Ag2S-based sensing element and coupled with a Zr/ZrO2 reference electrode, and YSZ/HgO/Hg electrode, had been tested for its potential response to H2S concentrations in fluids at temperatures from 0°C to 400°C and pressures up to 25 or 33MPa, and is well suited for determining dissolved H2S concentrations in aqueous media at elevated temperatures from 0°C to 400°C and at high pressures. The Ag/Ag2S electrode is made of an Ag wire with an Ag2S film coating, which can be pressurized and heated at high pressures and temperatures. The Nernstian response of the Ag/Ag2S–YSZ/HgO/Hg cell potential to H2S concentrations at 400°C and 25MPa is described as.ΔE (V)=0.625+0.0667 log mH2S. The Nernstian response of the Ag/Ag2S–Zr/ZrO2 potential to H2S at 1°C and 33MPa is described as:ΔE (V)=−0.261−0.02966 log mH2S.