Liquid membranes uranium recovery

Carrier (TOPO)-mediated transport of uranium(Vl) has been studied by Akiba and Hashrmoto [94] who have observed that uranium was extracted in the liquid membrane as U02(N03)2 2TOPO and stripped into the carbonate solutions as U02(C03)3. Using TOPO and HDEHP mixmre, liquid membrane technique was apphed for the recovery of uranium from WPPA [95]. Carrier-facilitated Pu(IV) pertraction through an SLM was standardized for its decontamination from oxalate wastes employing a commercially available Cyanex-923 (TOPO analog) in dodecane as the receptor [96,97]. More than 95% of plutonium could be easily recovered from Pu oxalate wastes solution during Pu reconversion operations. 

As a result, liquid-membrane processes have received a great deal of attention for the potential recovery of copper,uranium,1 11 and nickel.10,35,16... 

J>) reported on the application of emulsion liquid membrane technology to the recovery of uranium from wet process phosphoric acid. 

Pathak, P.N., Ansari, S.A., Prabhu, D.R., Kanekar, A.S., Mohapatra, P.K., and Manchanda, V.K. 2010. Selective recovery of uranium from THOREX feed by hollow fiber supported liquid membrane technique containing di(2-ethylhexyl) iso-butyramide (D2EHIBA) as the carrier. Radiochim. Acta 98 259-266. 

Apart from the work conducted by Li et al. at Exxon which is fully reported in the proceedings of a seminar on Liquid Membrane Applications in Waste Water Treatment and Metals Recovery held at UMIST in May 1980, investigations on applications of liquid membranes to metals recovery are conducted at a number of other places. Thus, extraction of copper is studied at UMIST (11, 12), Graz (13-15) and Bend Research (16). The last place is also active in the use of membranes for the extraction of uranium (17), whereas work on the extraction of copper, zinc, cadmium and lead is conducted by Boyadzhiev et al. (18). Extraction of different metals has also been studied by Stelmaszek (19) and Strzelbicki (20, 21) and of zinc alone at Imperial College (7). All the accumulated data point towards membrane extraction as a promising process for the solution of separation problems, particularly in dilute solutions. 

An especially intriraing use of liquid-membrane technology, reported for the first time recently by Fox and Hayworth et al.," is the recovery of uranium from wet process phosphoric acid (WPPA). In the manufacture of fertilizer fiom phosphate rock, the acid is solubilized by treatment with sulfuric acid. In addition to HjP04, this crude leachate can contain up to 0.18 g/L of uranium. Under oxidizing conditions this occurs as the uranate ion, UO . Solvent extraction (SX) processes have been developed to recover die uranium values. One of the most common of these uses a mixture of di-(2-ethylhexyl) phosphoric acid (D2EHPA) and trioctylpbosphine oxide (TOPO) in kerosene solution. The chemistry of solvent extraction is as follows ... 

Kulkami, PS. (2003) Recovery of uranium(VI) from acidic wastes using tri- -octylphosphine oxide and sodium carbonate based liquid membranes. Chemical Engineering Journal, 92,209-214. 

APPLICATIONS OF LIQUID MEMBRANES FOR URANIUM RECOVERY 8.4.1 Wet process phosphoric acid... 

Sifhiades, S., Largman, T., Ttmick, A.A. Koff, FW. (1981) Recovery of uranium from phosphoric acid by means of supported liquid membranes. Hydrometallurgy, 7 (3), 201-212. 

Singh, S.K., Misra, S.K., Sudersanan, M. Dakshinamoorthy, A. (2009) Studies on the recovery of uranium from phosphoric acid medium by D2EHPA/n-dodecane supported liquid membrane. Separation Science and Technology, 44 (1), 169-189. 

Table 9. Uranium Recovery in Double Emulsion Liquid Membrane (ELM)...

Table 31.3 gives a few typical examples on recovery of actinides by ELM. Myriad literature reports exist on the use of HDEHP for metal extraction involve ELMs. Comparative studies between column and batch liquid emulsion membrane techniques based on HDEHP/HCl system were carried out to develop a system for the isolation of Th from natural uranium, which showed that, kineticaUy, the equilibrium for thorium separation using batch technique is faster than the continuous column system [37]. The effective separation of Th from natural uranium was found to be independent of time. El-Sherif studied... 

El-Reefy, S.A., El-Sherif, E.A., and Aly, H.F., Recovery of Th from natural uranium using liquid emulsion membrane based on HDEHP-HCl system. J. Radioanal. Nucl. Chem., 1996, 207 129-136. 

KuUtami, P.S., Mukhopadhyay, S., Bellary, M.P., and Ghosh, S.K., Studies on membrane stability and recovery of uranium (VI) from aqueous solutions using a liquid emulsion membrane process. Hydrometallurgy, 2002, 64 49-58. 

El-Reefy, S.A., Selim, Y.T. Aly, H.F. (1998) Recovery of uranium from thorium in hydrochloric acid medium by liquid emulsion membranes containing trioctylphosphine oxide. Journal of Radioanalytical... 

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