Kinetics and mechanism of metal extraction with acidic organophosphorus extractants (I): Extraction rate limited by diffusion process

Separation of Cobalt and Nickel by Liquid Surfactant Membranes Containing a Synthesized Cationic Surfactant

“…Using LIX 65N, LIX 84, and LIX 860 as extractants in the liquid-liquid system, nickel ions were preferentially extracted over cobalt ions although only LIX 84 showed better selectivity. All the hydroxyoxime extractants appeared to have an affinity for forming chelate complexes with nickel ions, which is directly opposite of the results reported for organophosphorus extractants (1)(2)(3)8). Based on the relationship between the logarithm of metal distribution and pH, two protons are released from the extractant according to the valence of the reactants, cobalt(II) and nickel(II) cations.…”

“…This behavior is explained on the basis of an interfacial reaction model in which the decrease in the extraction rate is deduced to be due to the blocking effect of adsorbed surfactant molecules at the reaction interface. Further, the extraction rate also decreased in the surfactant concentration range of less than 20 mol/m 3 …”

“…Solvent extraction processes are among the most widely used techniques for the recovery of metal ions, and a huge collection of published research work is available. Although extensive studies on the extraction of cobalt and nickel have been conducted (1)(2)(3), in most of these studies either an organophosphorus compound such as di(2-ethylhexyl)phosphoric acid (D2EHPA) or 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) has been used as an extractant. Studies which have utilized hydroxyoxime extractants are relatively few.…”

Liquid membrane transport and separation of Zn2+ and Cd2+ from sulfate media using organophosphorus acids as mobile carriers

“…The SX of divalent metals (M 2+ ) from acidic sulfate solutions with an organophosphorus acid (HA) such as D2EHPA and PC88A has been widely investigated 13–18. When the concentration ratio of metal complexes to the total extractant in the organic phase (ie the organic loading) is low, the reaction stoichiometry can be written as follows: where the overbar refers to the organic phase.…”

Extraction equilibria and separation of phenylalanine and aspartic acid from water with di(2‐ethylhexyl)phosphoric acid

“…Taking aspartic acid as an example, the classical description of extraction reaction involving an acidic extractant is as follows: where (HX) 2 represents the D2EHPA dimers 13, 14. The mass‐action equilibrium constant K 1, Asp is written as Evidently, the parameters n and K 1, Asp can be obtained by plotting log ( D Asp+ [H + ]) versus log [(HX) 2 ].…”