Scholarlink

Abstract <p>The efficiency and stability of liquid–liquid extraction processes used in hydrometallurgy and nuclear fuel reprocessing are strongly dependent on the acidity of the aqueous phase. Variations in nitric acid concentration affect distribution coefficients, phase stability, and process selectivity, while deviations beyond allowable limits may lead to third-phase formation, precipitation, and operational shutdowns. These considerations make real-time monitoring of nitric acid concentration a critical technological task. In this work, a flow-through Raman spectroscopic setup is developed and experimentally tested for online determination of nitric acid concentration in aqueous solutions over a wide concentration range from 0.01 to 10 M. The method is based on the analysis of systematic changes in the shape and intensity of the broad OH stretching band of water in the 3000–3700 cm<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({}^{-1}\)</EquationSource> <!--BPhysMGU2670018Zherebtsov-m1--> </InlineEquation> region. Raman spectra were parameterized using a sum of Gaussian components associated with different hydrogen-bonding environments, and ratiometric spectral indicators based on their amplitudes were employed for calibration. Both linear and third-order polynomial calibration models were considered. Cross-validation using a leave-one-group-out scheme demonstrated that, for metal-free nitric acid solutions, the median absolute deviation of the predicted concentration is 0.14 M for the linear model and decreases to 0.07 M for the nonlinear model. The influence of matrix effects was studied by introducing uranyl ions at concentrations typical for extraction systems. In the presence of uranyl, the median deviation increases to approximately 0.35 M, remaining below 10<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\%\)</EquationSource> <!--BPhysMGU2670018Zherebtsov-m2--> </InlineEquation> for nitric acid concentrations above 3 M. The obtained results demonstrate that Raman spectroscopy with analysis of the OH stretching band provides a robust basis for online monitoring of nitric acid concentration in extraction-related aqueous streams and can be further extended to more complex technological media.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Online Monitoring of Nitric Acid Concentration in Extraction Process Streams Using Raman Spectroscopy

  • 期刊论文

  • 发表日期：

    2026年2月1日

查看全文
  • A. A. Zherebtsov,
  • M. A. Tarazanova,
  • G. A. Sharadze,
  • K. N. Dvoeglazov,
  • E. Yu. Pavlyukevich,
  • V. I. Panov,
  • V. A. Petrov,
  • G. S. Budylin

摘要

Abstract

The efficiency and stability of liquid–liquid extraction processes used in hydrometallurgy and nuclear fuel reprocessing are strongly dependent on the acidity of the aqueous phase. Variations in nitric acid concentration affect distribution coefficients, phase stability, and process selectivity, while deviations beyond allowable limits may lead to third-phase formation, precipitation, and operational shutdowns. These considerations make real-time monitoring of nitric acid concentration a critical technological task. In this work, a flow-through Raman spectroscopic setup is developed and experimentally tested for online determination of nitric acid concentration in aqueous solutions over a wide concentration range from 0.01 to 10 M. The method is based on the analysis of systematic changes in the shape and intensity of the broad OH stretching band of water in the 3000–3700 cm \({}^{-1}\) region. Raman spectra were parameterized using a sum of Gaussian components associated with different hydrogen-bonding environments, and ratiometric spectral indicators based on their amplitudes were employed for calibration. Both linear and third-order polynomial calibration models were considered. Cross-validation using a leave-one-group-out scheme demonstrated that, for metal-free nitric acid solutions, the median absolute deviation of the predicted concentration is 0.14 M for the linear model and decreases to 0.07 M for the nonlinear model. The influence of matrix effects was studied by introducing uranyl ions at concentrations typical for extraction systems. In the presence of uranyl, the median deviation increases to approximately 0.35 M, remaining below 10 \(\%\) for nitric acid concentrations above 3 M. The obtained results demonstrate that Raman spectroscopy with analysis of the OH stretching band provides a robust basis for online monitoring of nitric acid concentration in extraction-related aqueous streams and can be further extended to more complex technological media.