Diethylhexyl phosphoric acid

Note TBP = tributyl phosphate DEHPA = diethylhexyl phosphoric acid STTA = monothio-thenolytrifluoroacetone DMABR = 5-(4-dimethylaminobenzylidene)-rhodanine TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine LIX 63 = aliphatic a-hydroxyoxime LIX 65N = 2-hydroxy-5-nonylbenzophenoneoxime LIX 64N = a mixture of LIX 65N with approximately 1% (v/v) of LIX-63. 

Another commonly used extraction reagent for metal ions is diethylhexyl phosphoric acid (DEHPA) [55,56]. See Figure 12.3c. In this case a pH gradient must exist over the membrane, so the acceptor is kept more acidic than the donor (typically pH 1 and pH 3, respectively). Speciation of different chromium species (chromate and chromium ion) has been performed by the combination of two membrane extraction systems, one working with DEHPA for extraction of Cr + and the other with Aliquat-336 for extraction of the chromate anions [51]. Using the same principles, also organic compounds, such as amino acids [57] and polyamines [58], can be extracted. 

FIGURE 12.3 Membrane extraction schemes of metal ions (Me). HQ, 8-hydroxyquinoline DTPA, diethylenetriaminepentaacetic acid anion methyltrioctylammonium cation HD, diethylhexyl phosphoric acid. For a, b, and c, see the text. 

Leon G, Guzman MA. Facilitated transport of cobalt through bulk liquid membranes containing diethylhexyl phosphoric acid. Desalination 2004 162 211-215. 

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