Investigation of hydrogen sulfide adsorption using cavity ring-down spectroscopy

Abstract H 2 S is a toxic pollutant that threatens human health and industrial integrity by causing respiratory irritation, metal corrosion, and equipment damage. Accurate, real-time monitoring is critical due to strict emission regulations, but challenges persist in detecting low concentrations and addressing adsorption effects on material surfaces, complicating measurement accuracy. This study investigates the adsorption of H 2 S under continuous-flow conditions, examining various gas parameters and surface materials. Real-time monitoring of the adsorption process is performed using cavity ring-down spectroscopy for quantitative analysis, with absorption spectra in the range of 6335.9–6337.2 cm –1 employed to determine H 2 S concentrations. System performance is assessed through dynamic dilution measurements, reproducibility tests, and Allan variance analysis. The influences of the H 2 S concentration, gas flow rate, H 2 O content, and surface area on adsorption are also investigated. The results show that H 2 S adsorption increases with higher concentrations and larger surface areas but decreases with greater gas flow rates and H 2 O content. Furthermore, material analysis reveals that polymers and quartz adsorb less H 2 S than 304 stainless-steel, with polytetrafluoroethylene exhibiting the lowest adsorption. In conclusion, this study reveals that H 2 S adsorption varies with concentration, flow rate, surface area, and humidity. These insights aid in material selection and measurement optimization for accurate trace H 2 S detection.