高温高压下水溶液中硫酸根离子浓度的拉曼光谱定量测定研究

摘要

当前，拉曼光谱通常被应用于定性研究，拉曼光谱的定量研究明显不足。通过理论分析，拉曼光谱的定量研究应当基于其相对强度来进行。据此，通过对三种不同浓度的Na2 SO4溶液进行拉曼光谱分析，得到了常温常压下水溶液中SO2－4离子浓度的定量方程为：c（SO2－4）＝4.7796R（r2＝0.9994）。此外，对高温高压下硫酸根水溶液的拉曼光谱也进行了研究。光谱分析表明，温度和压力将影响拉曼谱峰强度比值与SO2－4浓度的关系。高温高压下水溶液中SO2－4浓度的定量方程为：c（SO2－4）＝4.7796（R＋1.469×10－4ΔT ＋1.340×10－4ΔP ），式中 c（SO2－4）为待测溶液中SO2－4的浓度， R为拉曼谱峰强度的比值R （SO2－4／H2 O ），ΔT为相对于常温（23℃）时的温度差，ΔP 为相对于常压（0.1 M Pa）时的压力差。该方程适用的温度范围为23℃≤ T≤360℃，浓度范围为0.5～1.5 mol · L －1，测量的相对误差为6.5％。对于具有拉曼活性的物质，拉曼光谱实验技术可以用来进行水溶液中物质浓度的定量研究。%In the present work ,the Raman spectra of SO2 -4 ions in aqueous solutions were studied .The quantitative analysis shows that there is a significant correlation between the Raman intensity ratio (R) and the SO2 -4 concentration .The SO2 -4 concen‐tration in aqueous solution at ambient temperature and pressure can be determined by the Raman intensity according to the linear fitting equation c(SO2 -4 )=4.779 6R(r2 =0.999 4) .Furthermore ,the research proves that the temperature and pressure will af‐fect the relationship between the Raman intensity ratio and the concentration of SO 2 -4 ions .The quantitative equation for measur‐ing the SO2 -4 concentration in aqueous solution at high temperature and high pressure is c(SO2 -4 )=4.779 6(R+1.469 × 10-4ΔT+1.340 × 10-4ΔP ) ,where R is defined as the ratio of the SO2 -4 ions band intensity to the OH stretching single band intensity ,ΔT is the temperature relative to 23 ℃ ,ΔP is the pressure relative to 0.1 M Pa ,23 ℃ ≤ T≤390 ℃ ,the concentration range of the SO2 -4 ions is 0.5~1.5 mol · L -1 ,and the uncertainty of the equation is 6.5% .Raman spectroscopy can be used to measure the concentration of the Raman‐active species in aqueous solutions .