Quantification of surface area and intrinsic mass transfer coefficient for ultrasound-assisted dissolution process of a sparingly soluble solid dispersed in aqueous solutions

Abstract

The efficacy of power ultrasound of 20 kHz in enhancing the volumetric mass transfer coefficient was investigated in this study. Breakage and dissolution of sparingly soluble benzoic acid dispersed in either water or 24% aqueous glycerol was monitored as a function of time and ultrasound power input. Particle size measurements were carried out at intermediate times during the experiment to estimate the mean particle size and surface area. Linear combination of lognormal distributions was found to fit the experimental particle size distribution data. The De Brouckere mean diameters (d(43)) obtained from the particle size distributions decreased with increase in the ultrasonic power level. Empirical correlations were developed for the evolution of surface area as a function of ultrasonic energy input per unit mass. The effect of ultrasound on the intrinsic mass transfer coefficient (k(c)) could be decoupled from the volumetric mass transfer coefficient (k(c)a) as the surface area was also estimated. Different approaches involving either constant or variable intrinsic mass transfer coefficients were employed when carrying out the delineation. Mass transfer rates were enhanced due to both higher ultrasound induced intrinsic convective mass transfer coefficient and additional surface area created from particle breakage. To delineate the effects of particle breakage from solid dissolution, experiments were also carried out under non-mass transfer conditions by pre-saturating the solvents with benzoic acid. Both the solid-liquid systems examined in the present study attained saturation concentration when the ultrasonic energy input per unit mass was approximately 60 kJ/kg, irrespective of the ultrasonic power level setting.

Using solid-phase microextraction during ultrasound reveals higher aqueous PAHs release from contaminated sediment

“…Comparing [PAH] at the 20 min time point of ultrasonic treatment, the measured concentrations of phenanthrene, anthracene, and fluoranthene were higher than in the mixing only condition ( Table 3 ). This enhanced desorption during sonication is consistent with many other studies showing this effect [8] , [14] , [20] , [52] . Treatment may cause PAHs embedded in the sediment to be subjected to acoustic microstreaming which can reach pore spaces and facilitate diffusional mass transfer [46] .…”

In vitro and computational studies of transdermal perfusion of nanoformulations containing a large molecular weight protein

“…Ultrasonication is utilized due to the inherent mechanisms of micro-stirring, compressions and decompressions that occur within the material [25]. The resulting heating and/or cavitation that also occurs contributes to the enhanced mass transfer and the ultimate formation of the nano scaled dispersions [26][27][28]. The homogenization phase of this process allows the formation of a homogeneous and stable surfactant-protein complex, which is then separated by lyophilization.…”

Construction of mathematical model of dissolution process of solids under action of ultrasound

“…There are studies of the effectiveness of ultrasonic irradiation frequency of 20 kHz to increase the mass transfer coefficient and dissolution of benzoic acid in water or in 24 % aqueous solution of glycerol [9]. In [10] the influence of ultrasonic irradiation is studied at a frequency of 19 kHz and power of 475 W on solid dispersion and increase of the solubility of insoluble drugs in water.…”

“…The next equation for dissolution processes of spherical granules under free convection is proposed in the literature [9]:…”