A calorimetric study of energy conversion efficiency of a sonochemical reactor at 500 kHz for organic solvents

Abstract

It would seem that the economic viability is yet to be established for a great number of sonochemical processes, owning to their perfectible ultrasonic equipments. Industrial scale sonoreactors may become more important as a result of mastering the parameters with influence on their energy balance. This work related the solvent type to the energy efficiency as the first step of a complex study aiming to assess the energy balance of sonochemical reactors at 500 kHz. Quantitative measurements of ultrasonic power for water and 10 pure organic solvents were performed by calorimetry for a cylindrically shaped sonochemical reactor with a bottom mounted vibrating plate. It was found that the ultrasonic power is strongly related to the solvent, the energy conversion for organic liquids is half from that of water and there is a drop in energy efficiency for filling levels up to 250 mm organic solvents. Surface tension, viscosity and vapor pressure influence the energy conversion for organic solvents, but it is difficult explain these findings based on physical properties of solvents alone. The apparent intensity of the atomization process shows a good agreement with the experimentally determined values for energy conversion for water and the solvent group studied here. This study revealed that to attain the same ultrasonic power level, more electrical energy is need for organic solvents as compared to water. The energy balance equation has been defined based on these findings by considering an energy term for atomization.

Determination of acoustic fields in acidic suspensions of peanut shell during pretreatment with high-intensity ultrasound

“…The maximum yield (82.7%) was observed for less concentrated suspensions, which is in accord with the values obtained by Toma et al (2011) for water. This high yield could be justified by the high yields obtained for ultrasound application using an apparatus with the sonotrode immersed instead of an ultrasonic bath (Kimura et al, 1996;Wu et al, 2001).…”

“…An effect related to different pH was not observed, and could not be distinguished as observed for specific heat. Toma et al (2011) andCárcel et al (2007b) also recorded a linear increase of temperature for different solvents (both at 500 and 20 kHz of frequency) and for sucrose solutions, respectively. Using dT/dt values calculated by linear regressions, the real power transmitted (P) and the acoustic intensity (I) as a function of the nominal power applied (U) from 80 to 320 W, biomass concentration (X) from 4 to 12% and pH from 3 to 7 were determined by Equations (2) In Figure 4 (left), the measured power transmitted increased when an increase in nominal power was applied.…”

“…Among these variables, there are physical properties (specific heat, viscosity, surface pressure and vapor pressure), liquid volume and/or height, input power, sonotrode type and position, etc. (Toma et al, 2011).…”

Assessment of two immobilized lipases activity and stability to low temperatures in organic solvents under ultrasound-assisted irradiation

“…Based on these aspects, one should expect that other parameters might be influencing the results obtained here, such as the functional groups of the solvents [36]. Liu et al [37] showed that the activity of lipases in organic solvents is not only dependent on the hydrophobicity (log P) but also the functional group of the solvents.…”

Designing and characterizing a multi-stepped ultrasonic horn for enhanced sonochemical performance

“…These include optimizing the geometries of reactors [4,12,13], applying different operational conditions (e.g., frequency, power input, and pulsing the ultrasonic signal) [14][15][16][17], and modifying sonication media (e.g., additives and purging oxygen) [16,[18][19][20]. A redesign of the horn configuration provides an alternative solution that potentially increases energy-emitting surfaces, reactive areas, and cavitation volumes [2,6,21].…”