Probing Aqueous Electrolytes with Fourier Spectrum Pulse-Echo Technique

TL;DR

This study uses Fourier Spectrum Pulse-Echo technique to investigate how ultrasonic wave velocity and attenuation vary with concentration in aqueous NaCl, KCl, and CsCl solutions, revealing distinct behaviors and fitting viscosity models.

Contribution

It introduces the application of FSPE for precise measurement of ultrasonic properties in electrolyte solutions, highlighting differences among salts and correlating with viscosity models.

Findings

NaCl and KCl show abrupt changes in v and α at specific concentrations.

CsCl exhibits smooth variation in ultrasonic velocity across concentrations.

Velocity variations fit well with the Jones-Dole viscosity equation.

Abstract

The nature of variations of ultrasonic wave velocity(v) and attenuation constant({\alpha}) with the concentration(c) in aqueous solutions of NaCl, KCl and CsCl are investigated at room temperature(250C) at 1MHz and 2 MHz wave frequency. Fourier Spectrum Pulse-Echo (FSPE) technique is used to achieve better accuracy in measurement, particularly for {\alpha} measurement. In NaCl and KCl abrupt changes in the values of v and {\alpha} are noticed at particular solution concentrations whereas, for CsCl almost smooth variation in v is observed over the whole concentration range for both of the frequencies 1 and 2 MHz . The nature of variation in v and {\alpha} in these solutions are analyzed in view of other spectroscopic studies. The well-known Jones-Dole equation that explains the viscosity({\eta}) variation in many electrolyte solutions, offers satisfactory fits to the experimental velocity variation with parameter values characteristics of the sample.