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

Abstract

-The benefits of high-intensity ultrasound in diverse processes have stimulated many studies based on biomass pretreatment. In order to improve processes involving ultrasound, a calorimetric method has been widely used to measure the real power absorbed by the material as well as the cavitation effects. Peanut shells, a byproduct of peanut processing, were immersed in acidified aqueous solutions and submitted to an ultrasonic field. Acoustic power absorbed, acoustic intensity and power yield were obtained through specific heat determination and experimental data were modeled in different conditions. Specific heat values ranged from 3537.0 to 4190.6 J·kg -1 ·K -1 , with lower values encountered for more concentrated biomass suspensions. The acoustic power transmitted and acoustic intensity varied linearly with the applied power and quadratically with solids concentration, reaching maximum values at higher applied nominal power and for less concentrated suspensions. A power yield of 82.7% was reached for dilute suspensions at 320 W, while 6.4% efficiency was observed for a concentrated suspension at low input energy (80 W).

Effect of intermittent high-intensity sonication and temperature on barley steeping for malt production

“…The resulting average ultrasonic power density obtained by the relationship between the ultrasonic energy delivered and the volume of water (1000 mL) varied from 0.0495 to 0.0522 W/mL and from 0.0829 to 0.0864 W/mL at 750 W and W, respectively, at the range of temperatures studied. As this work took into account energy transfer throughout the liquid medium (not only at the point of maximum cavitation), relative lower delivered energy was obtained compared to other studies (Polachini et al, 2017;Ozuna et al, 2014 increase is taken into account. However, the resulting actual ultrasonic density was similar or higher than other similar studies involving hydration assisted by bath type ultrasound (Patero and Augusto, 2015;Yildirim et al, 2011), even considering the integral method used to obtain real acoustic power.…”

“…The absorption of part of the acoustic energy into heat, which is proportional to the intensity and attenuation of the ultrasonic waves traveling through the medium, should be investigated to avoid undesirable effects (Raso et al, 1999). Generally, this determination has been made through the measurements of punctual temperature variations during the first periods of ultrasound application in different processes (Polachini et al, 2017;Margulis and Margulis, 2003;Chivate and Pandit, 1995). However, the energy is dissipated throughout the liquid and may not reach all of the material of interest.…”

Ultrasound-assisted acid hydrolysis of cassava (Manihot esculenta) bagasse: Kinetics, acoustic field and structural effects

“…Moreover, heating is a consequence of the resistance forces against acoustic vibration. This effect is useful for measuring the real acoustic power applied and for determining the proportion of acoustic energy transferred to the medium, this being important information for the purposes of reproducing similar conditions and scaling up the process [19] .…”

Thermophysical properties of dilute acid slurries of cassava bagasse as a function of biomass loading, acid concentration, and temperature

“…The mixture of cassava bagasse in acid solution can be modified according to the solids concentration, acid concentration and working temperature in order to obtain adequate conditions for efficient pretreatment, hydrolysis, fermentation and/or distillation. Aiming at working under nonaggressive treatment conditions, a cold hydrolysis of the cassava starch granules can be performed at subgelatinization temperatures 17 —avoiding problems regarding impaired mixing properties and reduced mass transfer, mainly if ultrasound is used as an enhancing technology 18 …”

“…Aiming at working under nonaggressive treatment conditions, a cold hydrolysis of the cassava starch granules can be performed at subgelatinization temperatures 17 -avoiding problems regarding impaired mixing properties and reduced mass transfer, mainly if ultrasound is used as an enhancing technology. 18 For this, the cassava bagasse conversion process should be correctly designed to avoid over-and underestimation of the required energy for each unit operation involved-for example, temperature control and mixing. Pino et al 19 emphasizes how imperative the design is of bioreactors and processing conditions to improve heat and mass transfer with low energy consumption.…”