Iranian Journal of Chemical Engineering (IJChE)

Abstract The droplet size distribution in the column is usually represented as the average volume to surface area, known as the Sauter mean drop diameter. It is a key variable in the extraction column design. A study of the drop size distribution and Sauter-mean drop diameter for a liquid-liquid extraction column has been presented for a range of operating conditions and three different liquid-liquid systems. The effects of rotor speed, and dispersed and continuous phase velocities on drop size are investigated. Drop size distribution are appropriately described using the normal and log-normal probability density functions. The mathematical approach is used to determine the constant parameters in these functions and to provide the fit of the experimental data with them. and empirical expressions are derived to predict the parameters of the distribution curve as a function of operating variables, and physical properties of the systems. Good agreement between the prediction and experiments was achieved for all investigated operating conditions. An empirical correlation is also proposed to predict the Sauter-mean drop diameter with mean deviation of 9.8%.

Abstract Adsorption of Ce(III) from aqueous solution by amino phosphate modified nano TiO2 was investigated. Effects of pH of solution, adsorbent dose, contact time, initial metal concentration and temperature were examined. Experimental data were fitted well by the pseudo second order model. Adsorption was well described by Freundlich isotherm model with a maximum adsorption capacity of 25 mg g-1. According to the obtained thermodynamic parameters, the adsorption was a spontaneous and endothermic process. Effect of interfering cations was studied. The presence of Ca and Mg ions up to 150 mg L-1 showed no considerable effect on the adsorption of Ce(III). Regeneration of adsorbent was performed using HNO3 with efficiency greater than 84%. The quantities of distribution coefficient (Kd), the affinity of metal for retention onto solid phase, was the higher for Ce(III) than La(III). Due to the high sorption capacity, being plentiful and low cost it is concluded that the use of amino phosphate mofified nano titania as an appropriate adsorbent is promising for the removal of lanthanides especially Ce(III) from contaminated sites.

Abstract Drop size distribution and Sauter-mean drop diameters have been measured in a pilot scale Hanson mixer-settler extraction column for two different liquid-liquid systems. The experiments were carried out for both mass transfer directions. The effects of agitation speed and dispersed phase and continuous phase flow rates have been investigated under a variety of operating conditions. Mean drop diameter axial profiles show a strong nonuniformity, while drop size distribution does not change significantly with the column height. Sauter mean diameter and drop size distribution are strongly affected by agitation speed and interfacial tension. Significant, but weaker are the effects of continuous phase and dispersed phase flow rates. An empirical correlation for mean drop size as a function of Weber number, dispersed phase holdup, and viscosities ratio is suggested. In a further correlation, the dispersed phase holdup is replaced by flow rates which will certainly be known in a practical case.

Abstract Sauter mean drop sizes have been measured in a pulsed packed extraction column for two liquid systems with and without mass transfer conditions. The effects of pulsation intensity, phase flow rates, and interfacial tension on drop size have been investigated under a variety of operating conditions. The drop size is influenced mainly by pulsation intensity and interfacial tension. Significant, but weaker, are the effects of continuous and dispersed phase flow rates. A precise correlation is proposed for predicting mean drop size in terms of operating variables, physical properties of the liquid systems and mass transfer direction. Good agreement between prediction and experiments is found for all operating conditions that were investigated.