Comparative Investigations on the Effects of Contamination and Mass Transfer Direction in Liquid−Liquid Extraction

Compensating effect of ultrasonic waves on retarding action of nanoparticles in drops liquid-liquid extraction

The influence of ultrasonic waves on liquid-liquid extraction of circulating drops and in the presence of magnetite nanoparticles was investigated. Experiments were conducted in a column equipped with an ultrasound transducer. The frequency and intensity of received waves, measured by the hydrophone standard method, were 35.40 kHz and 0.37 mW/cm², respectively. The recommended chemical system of cumene-isobutyric acid-water was used in which mass transfer resistance lies in the aqueous phase. Nanoparticles, within concentration range of (0.0003-0.0030) wt%, were added to the aqueous continuous phase. The presence of nanoparticles and ultrasonic waves provided no sensible change in drop size (within 2.49-4.17 mm) and measured terminal velocities were close to Grace model. However, presence of nanoparticles, caused mass transfer to decrease. This undesired effect was significantly diminished by using ultrasonic waves so that mass transfer coefficient increased from (73.0-178.2) to (130.2-240.2) µm/s, providing a 55.6% average enhancement. It is presumably due to disturbing the accumulated nanoparticles around the drops. The current innovative study highlights the fact that using ultrasonic waves is an interesting way to improve liquid-liquid extraction in the presence and absence of nanoparticles.

Experimental studies on the effect of ultrasonic waves on single drop liquid-liquid extraction

The influence of ultrasonic waves on hydrodynamics and mass transfer of circulating drops in liquid-liquid extraction process was studied. The recommended chemical systems of toluene-acetic acid-water with mass transfer resistance mainly in the organic phase, and cumene-isobutyric acid-water in the aqueous phase were used. An extraction column, equipped with an ultrasonic emitter of 35.40kHz real frequency and 0.37mW/cm² intensity, was employed. The ultrasound properties were measured using the hydrophone standard method. Drops terminal velocity was comparable with the Grace model. In mass transfer study, significant enhancement was revealed in overall mass transfer coefficient for different drop sizes and for the both mass transfer directions by using ultrasonic waves. The average and maximum enhancements were, respectively, 20.8 and 31.7% for toluene-acetic acid-water, and 40.3 and 55.1% for cumene-isobutyric acid-water. Small drops exhibited a higher enhancement percentage. Regarding the mass transfer direction, the system of cumene-isobutyric acid-water with continuous to dispersed phase direction, was benefited more as the consequence of creating effective agitation in continuous phase than in dispersed phase.