Probing aqueous electrolytes with Fourier Spectrum Pulse-Echo technique

Abstract

The nature of variations of ultrasonic wave velocity( ) and attenuation constant(α) with the concentration(c) in aqueous solutions of NaCl, KCl and CsCl are investigated at room temperature(25 0 C) at 1MHz and 2 MHz wave frequency. Fourier Spectrum Pulse-Echo (FSPE) technique is used to achieve better accuracy in measurement, particularly for α measurement. In NaCl and KCl abrupt changes in the values of and α are noticed at particular solution concentrations whereas, for CsCl almost smooth variation in is observed over the whole concentration range for both of the frequencies 1 and 2 MHz . The nature of variation in and α in these solutions are analyzed in view of other spectroscopic studies. The well-known Jones-Dole equation that explains the viscosity(η) variation in many electrolyte solutions, offers satisfactory fits to the experimental velocity variation with parameter values characteristics of the sample.

Study of the Optimal Waveforms for Non-Destructive Spectral Analysis of Aqueous Solutions by Means of Audible Sound and Optimization Algorithms

“…The nine frequencies of the combined classifier are located in the range (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) kHz. These frequencies have been highlighted in Figure 5 on the spectral information of the vibrational absorption bands for each concentration of Table 1.…”

“…This work has allowed us to reduce the problem to a set of only nine frequencies on (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) kHz able to classify samples with concentrations of any of the three sets described. In the most complex case, the proposed classifier was able to discriminate fructose concentrations with variations of ±0.01 g/L with an average accuracy of 98.65%.…”

“…Table 4 lists the frequencies (kHz) of the independent classifiers. Classifier 1 consists of 4 frequencies in the range (8-15) kHz, and Classifier 2 selects five frequencies in the range (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)) kHz. The two classifiers are combined into a single classification system.…”

“…However, there have been remarkable advances in recent years, as can be seen, for example, in [9][10][11][12]. The acoustic research of aqueous electrolytes was performed by Pal and Roy in [13] using the Fourier spectrum pulse-echo technique, which is discussed in detail in [14].…”

“…For a detailed review of ultrasound spectroscopy for particle size determination see [15]. In [16] Silva et al studied polydisperse emulsions by means of acoustic spectroscopy within the frequency range of (6)(7)(8)(9)(10)(11)(12)(13)(14) MHz in order to measure the droplet size distribution of water-in-sunflower oil emulsions for a volume fraction range from 10 to 50%. They concluded that the methodology was suitable for polydisperse particle size characterization for moderate concentrations up to 20% and the results were in good agreement with those obtained by laser diffraction analysis.…”