Electrochemical sensors for H2S determination

Electrochemical techniques anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) for determining trace elements, and potentiometric sensors for determining dissolved gases (C02, N02, S02, NH3, H2S, HCN, and HF) as well as chloride, fluoride, cyanide, and sulfide. 

Determination of pollutants in the air. For the determination of SO2, H2S, NO, N02 CO, 02 O3, HCN, HCl, HF in the air many electroanalytical methods were published. Commercially produced instruments based on poten-tiometry, coulometry, voltammetry, conductometry, or using as sensor an electrochemical cell are available on the market. The application range is mostly from 0.1 to 10 ppm are available. Pocket size "personal" dosimeters for 02> CO, HCN, NO2, H2S which signal acoustically if the takehold concentration has been reached. It can also be expected that personal monitors... 

Fig. 15.4 ScatlCT plots of the gas mixing ratios derived from the electrochemical sensor data of Fig. 15.3, shown as X vctsus SO2 where X is H2, CO or H2S. The estimate of H2S from N02-A1 sensor is preferred over that of H2S-A1 sensor which exhibits enhanced scatter see text for explanation. Linear regression is used to determine the characteristic gas ratios in the Aso volcano fumarole emission...

Shinohara performed a UAV-based characterisation of the plume from Shinmoedake, Kirishima volcano, Japan, using electrochemical and other in situ sensors. Due to ongoing explosive eruptive activity, access to the volcano summit area 4 km around the volcano was restricted (even for manned aircraft). Therefore this study demonstrates UAVs as a viable method to obtain plume gas measurements under hazardous summit conditions. Several molar gas ratios were determined during a period with Vulcanian eruptions in May 2011, including CO2/ S02 = 8, H20/C02 = 70 and H2/S02 = 0.03. It was found that plume SO2/H2S showed a decrease over March to May 2011 from 8 to 0.8, which is interpreted as resulting from an increase in degassing pressure of the volcano. 

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