Nickel(II) Extraction from Sulphate Media with Bis (2,4,4‐Trimethylpentyl)Dithiophosphinic Acid Dissolved in Nonane

Investigation of the State of Bis(2,4,4‐Trimethylpentyl)dithiophosphinic Acid in Nonane and Toluene Solutions

“…This contradicts the data from 746 N.A. Grigorieva et al other work that reported that the extractant is present mainly in the monomeric form when its total concentration is (0.1 M. [10,12,14] The vapor pressure osmometry (VPO) method was used to study the aggregation of unpurified Cyanex 301 in toluene (HR total 5 0.2-0.4 M) [7] and benzene (HR total 5 0.1 M), [15] and the method of small angle neutron scattering (SANS) was used to study the aggregation of purified Cyanex 301 in deuterated toluene (HR total 5 0.1 M). [16] All these experiments show that independent of the type of solvent (toluene, benzene, or deuterated toluene) and whether the extractant is purified or not, Cyanex 301 exists as a monomer in the organic phase across the studied extractant concentration range (up to 0.4 M in toluene).…”

“…It will suffice to refer to the papers on nickel extraction with Cyanex 301, in which the following compositions of the extracted complexes have been reported: Ni(HR 2 ) 2 (HR) 2 in xylene, [6] NiR 2 (H 2 O) 2 in toluene, [7] NiR 2 (H 2 O) 2 in Exxsol D-80 (a dearomatized aliphatic hydrocarbon), [8] NiR 2 (HR) 2 in hexane, [9] and NiR 2 in nonane. [10] In our opinion, such contradictory results were mainly caused by the views of different authors regarding the state of the extractant in the diluents. Thus, for example, in the studies referred to in references [6,8] dithiophosphinic acid is considered to be totally dimeric, whereas in other studies [7,9] the acid is considered to be monomeric.…”

“…The presented data are in good agreement with the results of earlier work, [20,21] where it was shown that diethyldithiophosphinic and diphenyldithiophosphinic, [20] as well as dipropyldithiophosphinic [21] acids in inert diluent solutions are predominantly monomeric up to a The monomeric form is present over all concentration ranges of dithiophosphinic acid studied, and on increasing the total extractant concentration the monomeric form fraction essentially decreases and does not exceed 40% for a 1.0 M HR solution. [10] By substituting the aliphatic diluent nonane for the aromatic one, namely toluene, the state of the extractant is noticeably changed, which is reflected in the IR spectra. As seen from Fig.…”

“…[10] and for the slope analysis of the experimental data, the least squares method was used. The accuracy of the calculated values was characterized by confidence bands for a confidence probability of 95% and similarly for equilibrium constants by standard deviation.…”

“…In our previous work, [10] the state of nonane diluted bis(2,4,4-trimethylpentyl)dithiophosphinic acid solutions was investigated. Taking into account the importance of the problem further, it was concluded that more extended investigations on this topic were necessary.…”