Hollow-fiber nondispersive extraction

Lanthanide-actinide separation was also attempted by HFSLM (operated in the nondispersive extraction mode) method using diphenyldithiophosphinic acid derivatives. Geist et al. have employed a synergistic mixture of bis(chlorophenyl)-dithiophosphinic acid and TOPO in a hollow fiber module for the lanthanide-actinide separation [168]. About 99.99% Am... 

As a part of our comprehensive programme on membrane technology, we evaluated nondispersive solvent extraction (NDSX) with a hydrophobic microporous hollow fiber contactor (HFC) for the separation and removal of actinides [1,10-12]. As the separation and recovery of actinides from different sources is paramount to radiotoxicity, there is a constant need for advances in the field. Among recently developed technologies, membrane extraction using microporous hollow fibers is particularly... 

In other advanced SILMs technologies, though not essentially SILMs in themselves, they used a solid microporous barrier to separate the aqueous phase from the organic one. Including in this concept are the nondispersive solvent extraction (NDSX) and pseudo-emulsion-based hollow-fiber strip dispersion (PEHFSD). 

FIGURE 26.4 (a) Schematic of nondispersive solvent extraction technique 1, hollow fiber module 2, aqueous phase (from tube side) ... 

Patil, C.B., Mohapatra, P.K., Singh, R.R., Gurba, P.B., Janardan, P, Changrani, R.D., and Manchanda, V.K. 2006. Transport of uranium from nitric acid solution by nondispersive solvent extraction using a hollow fiber contactor. Radiochim. Acta 94 331-334. 

In what follows the methodology for the selection of the operating conditions of a nondispersive solvent extraction process will be developed. As an example the removal and recovery of Cr(VI) from an indnstrial effluent of a surface treatment plant will be considered. The kinetic modeling including the extraction reactions. Equation (6.17) and Equation (6.22), and the mass balances of chromium compounds to the three fluid phases and considering the hollow fiber modules and the homoge-neization stirred tanks. Equation (6.30) through Equation (6.50) were described in Sections 6.3 and 6.4. 

Almost all countercurrent extraction devices utilize dispersion of one immiscible phase as drops in another immiscible phase we will provide a brief introduction here. At the end, we will introduce porous hollow fiber membrane based nondispersive countercurrent solvent extraction devices. The dispersive devices may involve continuous agitation or no agitation at all. Dispersive devices without any agitation as such are of three types spray towers packed towers perforated plate towers. Spray towers were illustrated in Figure 8.1.2(b). 

Figure 8.1.35(f) illustrates a porous membrane based solvent extraction device. Figure 8.1.13(a) illustrated the basic design of such devices in greater detail The basic principle of nondispersive contact of two immiscible liquid phases at the mouth of the pore of a membrane has been described earlier (see Figure 3.4.11, Section S.4.3.2) (Kiani et ah, 1984 Prasad and Sirkar, 1988). Large-scale devices built based on such a principle and related patents (Sirkar, 1991, 1995) are being used. One of the liquids (liquid is brought in through a central liquid distributor with circumferential perforations, which allows the liquid to flow out radially through the hollow fiber bundle. The device has a central baffle, which turns around the shell-side liquid ti, to the second half of the device, where this liquid flows radially inward in the fiber bundle to the central liquid distributor tube, which is blocked in the middle to insulate inlet liquid from exiting liquid...

---