Numerical simulation was made of transient mass transfer to a surfactant contaminated uoyancy-driven drop controlled by appreciable resistance in both liquid phases. For this purpose, the momentum equations were formulated and solved in a boundary-fitted orthogonal coordinate system. On the basis of resolved hydrodynamics of the contaminated drop, the transient mass transfer was formulated and solved in the same coordinate system. In order to check the applicability of the numerical scheme, single drop extraction experiments were conducted in a totally closed droplet file column with the terminal effect efficiently eliminated. The MIBK-acetic acid-water system was used with small quantities of SDS (sodium dodecyl sulphate), Trito X-100, or Tween 80 introduced into the continuous phase. For these experimental cases, the flow field and the drag coefficient of a contaminated drop were simulated first. The numerical prediction of the drag coefficient is found in good agreement with the correxponding experimental data. It illustrates that the behavior of a drop approaches that of a rigid sphere and that about 100 times higher bulk concentration of SDS than that of Triton X-100 is required for the same extent contamination of a MIBK drop of the same size. Then the information of the flow field of a contaminated MIBK drop was used in simulating the transient mass transfer of solute into the drop. The resulted extraction fraction and overall mass transfer coefficient are in reasonable coincidence with the experimental data. Both numerical results and experimental data show that overall mass transfer coefficient of a heavily contaminated drop is only about one third of that in the pure system. This can be explained well by the distribution of the local Sherwood number, which drops down abruptly along the rear stagnant surface. Also the interfacial resistance of adsorbed surfactant was incorporated in the mass transfer model and then estimated by the least square fitting the simulation with data. The numerical results also show that Tween 80 presents obvious interfacial resistance on the acetic acid diffusing across the interface, whereas SDS and Triton X-100 show no interfacial resistance. It is Suggested that the numerical simulation can be resorted in some solvent extraction systems containing surfactants to conduct numerical experiments and parametric study.

A new HPLC stationary phase, 1-methylnaphthalene modified Polystyrene-divinylbenzene resin (MNPSDVB), has been prepared to separate C60 and C70. High Column loading capacity and large separation factor of C60 and C70 were obtained in MNPSDVE column with the strong solvent, o-xylene, as the mobile phase.

The Pulsed packed column (PPC) uses pultation to enhance mass transfer. Systermat expertments (Spaay et al., 1971; Bender et al., However, only comentional packion such as Rasching rings and Pall rings were used in these experirenus. Packing types have been shown to inlluence the hydrodynumics and mass transfer characteristics of PPC (Bender et al., 1979; Simans et al., 1986). Several kinds of high efficiency packing, including randosn packing and structured packing, have been developed in recent years, but there are only a few studies on the characteristies of PPC (Hoting and Vogelpohl, 1996a, b) with these new packings. SMRs (Fei et al, 1991) are newfy devetoped mini rings with an elaborate geometrical design A photo of the SMR is shown in Figure 1. It has three afches and a lower height/diameter ratio (about 0.3), which has been shown to enhance the dispersion-coalescence cycle and contral the non-ideal flow of the two phases in the packing elements. Experiments (Fei et al., 1993) showed that the SMR has lower axial mixing and higher mass transfer etficiency than many corwentional packing, This, studies on the hydrodynamics and ruass transter characteristics of PPC with stainless steel SMR is presented in thas work. Experiments with cenamic and starless steel Rasching rings were also done for comparison.