This work aims to quantify sulfate ion concentrations in the system Na_2SO_4-H_2O using Raman micro-spectroscopy.Raman spectra of sodium sulfate solutions with known concentrations were collected at ambient temperatur...This work aims to quantify sulfate ion concentrations in the system Na_2SO_4-H_2O using Raman micro-spectroscopy.Raman spectra of sodium sulfate solutions with known concentrations were collected at ambient temperature（293 K） and in the 500 cm^（_1）-4000 cm^（-1） spectral region.The results indicate that the intensity of the SO_4^（2-） band increases with increasing concentrations of sulfate ion.A linear correlation was found between the concentration of SO_4^（2-）（c） and parameter I_1,which represents the ratio of the area of the SO_4^（2-） band to that of the O-H stretching band of water（A_s/A_w）：I_1=-0.00102＋0.01538 c.Furthermore,we deconvoluted the O-H stretching band of water（2800 cm^（-1）-3800 cm^（-1）） at 3232 and 3430 cm^（-1） into two sub-Gaussian bands,and then defined Raman intensity of the two sub-bands as A_（Bi）（3232 cm^（-1）） and A_（B2）（3430 cm^（-1））,defined the full width of half maximum（FWHM） of the two sub-bands as W_（B1）（3232 cm^（-1）） and W_（B2）（3430 cm^（-1））.A linear correlation between the concentration of SO_4^（2-）（c） and parameter I_2,which represents the ratio of Raman intensity of SO_4^（2-）（A_s）（in 981 cm^（-1）） to（A_（B1）＋A_（B2））,was also established：I_2=-0.0111＋0.3653 c.However,no correlations were found between concentration of SO_4^（2-）（c） and FWHM ratios,which includes the ratio of FWHM of SO_4^（2-）（W_s） to W_（B1） W_（B2） and W_（B1＋B2）（the sum of W_（B1） and W_（B2））,suggesting that FWHM is not suitable for quantitative studies of sulfate solutions with Raman spectroscopy.A comparison of Raman spectroscopic studies of mixed Na_2SO_4 and NaCI solutions with a constant SO_4^（2-） concentration and variable CI^- concentrations suggest that the I／ parameter is affected by CI^-,whereas the I_2 parameter was not.Therefore,even if the solution is not purely Na_2SO_4-H_2O,SO_4^（2-） concentrations can still be calculated from the Raman spectra if the H_2O band is deconvoluted into two sub-bands,making this method potentially applicable to analysis of natural fluid inclusions.展开更多
The phase diagram of system Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O has been investigated by many authors. The left part （Al<sub>2</sub>O...The phase diagram of system Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O has been investigated by many authors. The left part （Al<sub>2</sub>O<sub>3</sub>·3H<sub>2</sub>O as solid phase） of the diagram of Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O system is of no problem, but the right part （hydrated sodium aluminates as solid phases） is in controversies. Jucaitis concluded that there were two hydrated sodium aluminates, i.e. Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2.5H<sub>2</sub>O and 3Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·6H<sub>2</sub>O. Kuznetsov suspected the existence of the latter and believed that it was actually a mixture of Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2.5H<sub>2</sub>O展开更多
文摘This work aims to quantify sulfate ion concentrations in the system Na_2SO_4-H_2O using Raman micro-spectroscopy.Raman spectra of sodium sulfate solutions with known concentrations were collected at ambient temperature（293 K） and in the 500 cm^（_1）-4000 cm^（-1） spectral region.The results indicate that the intensity of the SO_4^（2-） band increases with increasing concentrations of sulfate ion.A linear correlation was found between the concentration of SO_4^（2-）（c） and parameter I_1,which represents the ratio of the area of the SO_4^（2-） band to that of the O-H stretching band of water（A_s/A_w）：I_1=-0.00102＋0.01538 c.Furthermore,we deconvoluted the O-H stretching band of water（2800 cm^（-1）-3800 cm^（-1）） at 3232 and 3430 cm^（-1） into two sub-Gaussian bands,and then defined Raman intensity of the two sub-bands as A_（Bi）（3232 cm^（-1）） and A_（B2）（3430 cm^（-1））,defined the full width of half maximum（FWHM） of the two sub-bands as W_（B1）（3232 cm^（-1）） and W_（B2）（3430 cm^（-1））.A linear correlation between the concentration of SO_4^（2-）（c） and parameter I_2,which represents the ratio of Raman intensity of SO_4^（2-）（A_s）（in 981 cm^（-1）） to（A_（B1）＋A_（B2））,was also established：I_2=-0.0111＋0.3653 c.However,no correlations were found between concentration of SO_4^（2-）（c） and FWHM ratios,which includes the ratio of FWHM of SO_4^（2-）（W_s） to W_（B1） W_（B2） and W_（B1＋B2）（the sum of W_（B1） and W_（B2））,suggesting that FWHM is not suitable for quantitative studies of sulfate solutions with Raman spectroscopy.A comparison of Raman spectroscopic studies of mixed Na_2SO_4 and NaCI solutions with a constant SO_4^（2-） concentration and variable CI^- concentrations suggest that the I／ parameter is affected by CI^-,whereas the I_2 parameter was not.Therefore,even if the solution is not purely Na_2SO_4-H_2O,SO_4^（2-） concentrations can still be calculated from the Raman spectra if the H_2O band is deconvoluted into two sub-bands,making this method potentially applicable to analysis of natural fluid inclusions.
文摘The phase diagram of system Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O has been investigated by many authors. The left part （Al<sub>2</sub>O<sub>3</sub>·3H<sub>2</sub>O as solid phase） of the diagram of Na<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O system is of no problem, but the right part （hydrated sodium aluminates as solid phases） is in controversies. Jucaitis concluded that there were two hydrated sodium aluminates, i.e. Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2.5H<sub>2</sub>O and 3Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·6H<sub>2</sub>O. Kuznetsov suspected the existence of the latter and believed that it was actually a mixture of Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2.5H<sub>2</sub>O
