Quantitative Raman spectroscopic investigation of geo-fluids high-pressure phase equilibria: Part I. Accurate calibration and determination of CO2 solubility in water from 273.15 to 573.15 K and from 10 to 120 MPa

Quantitative Raman spectroscopic investigation of geo-fluids high-pressure phase equilibria: Part II. Accurate determination of CH4 solubility in water from 273 to 603 K and from 5 to 140 MPa and refining the parameters of the thermodynamic model

“…3) [44]. The quantitative factor (QF, PAR/mCH 4 ) is temperaturedependent and increases linearly with temperature from 273.15 to 603.15 K, while pressure shows little effects on it.…”

“…The procedures for preparation of CH 4 saturated solution for solubility measurements and preparation of CH 4 homogeneous aqueous solutions with constant CH 4 concentration for calibrating a Raman system are identical to those in Guo et al [44]. The temperature was measured by a K-type thermo couple with accuracy of AE0.…”

“…The limitation of temperature and pressure range of gas solubility data obtained from experimental measurements is mainly due to constraints on temperature-and pressure-tolerant capabilities of instruments and apparatus, and/or on the methodologies for accurately determining gas saturation concentrations under highpressure conditions [44].…”

“…In our previous work, Guo et al, [44] developed an accurate method to calibrate Raman system for in situ quantitative Raman spectroscopic study of high pressure phase equilibria of geo-fluids, and determined CO 2 solubility in water in a temperature range from 273.15 to 573.15 K and pressures from 10 to 120 MPa. The method can effectively avoid errors caused by the sampling process, and the equilibrium between aqueous solution and gasrich phase could be reached in a short time.…”

Temperature and salinity effects on the Raman scattering cross section of the water OH-stretching vibration band in NaCl aqueous solutions from 0 to 300 °C

“…Apart from application of Raman spectroscopy to molecular interactions, quantitative analytical application of Raman spectroscopy has been developed successfully in both laboratory and submarine environment at various temperature–salinity–pressure conditions because of its non‐destructive and non‐contact advantages. Indeed, the water stretching Raman band is often used as internal standard in the determination of aqueous dissolved species concentration in the molality scale . In our previous works, Ou et al found that the Raman peak area ratio (PAR = A CH4 / A H2O ) between the stretching bands of methane and water was affected by temperature and salinity, and the effect of dissolved NaCl on the PAR/mCH 4 (mCH 4 the concentration of CH 4 by mol/kg·H 2 O) became more and more significant with increasing temperature.…”