| Seawaters penetrate down along the fracture or fissure of the oceanic crust,and react with rocks during the infiltration process.After being heated and modified,endmember hydrothermal vent fluids are formed with rich chemical components such as H2S,Si,Fe,Mn.As an important acid gas,H2S plays an important role in the process of mineralization and microbialization in submarine hydrothermal systems.Quantitative analysis of H2S in hydrothermal vent fluids will help to better understand the formation mechanism of submarine polymetallic sulphide deposits and the distribution of microbial community near hydrothermal vents.As a relatively common analyzing method of dissolved gases,Raman spectroscopy enables rapid,in situ,real-time,contactless qualitative and semi-quantitative analysis.In this paper,In-situ Raman spectroscopy technology has been used to analyze the dissolution process of H2S in 3.2 wt%NaCl solutions under the experimental conditions of 0-300? and 0-40 MPa,in order to effectively determine physicochemical parameters of H2S and provide basic data support for the interpretation of corresponding key scientific issues.The main work of this paper includes the following two aspects:1)Establish an experimental platform for in-situ analysis of H2S.According to the volatility,toxicity and strong corrosive properties of H2S,combined with fused silica capillary tube technology,high pressure visualization reaction chamber and in-situ online visible Raman spectroscopy system,a platform suitable for in situ analysis of H2S under laboratory conditions was established;2)Establish a test method for semi-quantitative analysis of the dissolution process of H2S in NaCl solutions.Combining the measured Raman spectral data with the existing solubility model,the Raman spectroscopy characteristics of H2S and H2O components in NaCl solutions under specific conditions were investigated,and the empirical formulas between the solubility of H2S in NaCl solutions and the normalized Raman peak intensity were obtained.The experimental results show that:1)In the H2S-H2O-NaCl system,the Raman characteristic peaks of H2S and H2O had obvious responses to temperature changes,and had no obvious or almost no response to pressure changes.Under certain pressure conditions,the Raman characteristic peak of H2S had a tendency to move toward the lower wavenumber direction and then to the higher wavenumber direction as the temperature increased,and its FWHM tended to be gradually narrowed;the Raman characteristic peak of H2O had a tendency to move toward the higher wavenumber as the temperature increased,and its FWHM also tended to be gradually narrowed.2)In the H2S-H2O-NaCl system,the solubility of H2S had a linear relationship with its normalized Raman peak intensity.So,the peak area ratio or peak height ratio could be used to characterize the solubility of H2S in the system.Based on Akinfiev and Peng solubility models,empirical formulas between the Raman characteristic peak intensity and solubility of H2S in NaCl solutions were established:mH2s=-0.529599+3.271266HR-0.402038HR2(root mean square error = 0.1941 and correlation coefficient=0.9818);mH2s=0.005741+24.373869PAR(root mean square error?0.0456 and correlation coefficient=0.9985).The empirical formulas can be applied to predict the solubility of H2S in brine systems with a mass fraction of about 3.2 wt%under the experimental conditions(0-300 0C,0-40 MPa). |
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