Agitated‐pulsed column (APC) is a newly designed extraction column with excellent mass transfer performance. In this work, Sauter mean drop diameter d32 and drop size distribution was investigated under different operation conditions in a 25 mm diameter APC. The results show that with an increase in pulsation intensity and agitation speed the drop size distribution is narrowed and d32 is decreased significantly. With increasing dispersed‐phase velocity, d32 increased and drop size distribution become narrow, while there was no noticeable change with continuous velocity. The cumulative size distribution was found to be predicted well using the Inverse Gaussian function. A new correlation was proposed to predict the experimental d32 data of the APC column used in this study. Furthermore, population balance model was applied to predict the drop size distribution with refitted parameters in the breakage, coalescence kernels functions.
The agitated‐pulsed column (APC) is expected to exhibit good transfer. The dispersed‐phase holdup and characteristic velocity were measured using a 25‐mm diameter APC. The holdup declined at first and then escalated with the increase of pulsation intensity which was in contrary to the trend of the characteristic velocity change. The pulsation intensity corresponding to minimum holdup was found, and it increased with higher agitation speed. The interfacial area was also calculated. Correlations were developed for the holdup and characteristic velocity prediction within 5.34 % and 9.54 % deviation, respectively. Flooding lines were calculated by the characteristic velocity method and operating regimes were determined by the experimental results.
Replacement
of volatile organic compound solvents by greener or
more environmentally sustainable solvents is becoming increasingly
important due to the increasing health and environmental concerns.
In the present work, a bioderived solvent, soybean oil methyl ester,
which is better known as biodiesel and is a nonvolatile organic compound,
was used as a solvent to replace the fossil solvent (kerosene) for
phenol extraction. First, biodiesel was selected as an optional solvent
to replace kerosene based on Hansen solubility parameter calculation
results. Second, the effects of solvent concentration, equilibrium
pH of the aqueous phase, temperature, extraction time, etc. on phenol
extraction were examined. The results show that biodiesel has strong
extraction ability on phenol extraction than that of kerosene. An
acidic environment decreases the phase disengagement time. Phenol
extraction reached equilibrium in 30 s of contact time at room temperature. McCabe–Thiele
diagram calculation results show that the phenol extraction efficiency
can reach 98% in three theoretical stages at an A/O ratio of 10:1
(Cyanex923 + biodiesel). Finally, the extraction mechanism indicated
that biodiesel could reduce the intermolecular hydrogen bond forces
in the extractant so as to improve the extraction efficiency.
In this work, the residence
time distribution (RTD) of the dispersed
phase (aqueous phase) and continuous phase (organic phase) in an agitated–pulsed
extraction column (APC) was measured online with a step tracer injection
technique and the axial dispersion was subsequently calculated via
RTD analysis. It was found that both the agitation speed and the pulsation
intensity had noticeable effects on the axial dispersion of the dispersed
phase, which escalates with the increase in the agitation speed and
this is especially authentic at high pulsation intensity. The dispersed-phase
axial dispersion coefficient also becomes higher with the increase
in the dispersed-phase velocity. Compared with the dispersed-phase
axial dispersion in the APC, the continuous-phase axial dispersion
is 2–3 times higher. Empirical equations have been proposed
to correlate the dispersed- and continuous-phase axial dispersion
coefficients for variation of both agitation and pulsation conditions
in APC. This study could be valuable for assessing the dispersed-phase
axial dispersion in liquid–liquid extraction columns.
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