Individual Extraction Constants Research Articles

Reactive extraction for the recovery of primary amines from aqueous streams

Biotechnological transformations promise to be an ecologically and economically efficient alternative for the production of amines and amino alcohols. Limitations in the use of these transformations often arise from inhibitory effects due to amine toxicity or from unfavorable reaction equilibrium. One solution to overcome these limitations is the continuous recovery of the amine from the biotechnological reaction media via a suitable in situ product removal strategy such as liquid–liquid reactive extraction. In this study, we investigate liquid–liquid reactive extraction for the recovery of 3-methylbutylamine, 1-phenylethylamine and 3-amino-1-propanol from aqueous streams, using a mixture of oleic acid and 1-octanol. For all investigated amines, high extraction yields of up to 99% and back extraction yields of over 90% of the extracted amine were observed. Relevant parameters such as chemical structure of the amine, the aqueous pH and the oleic acid concentration were identified. Furthermore, a mass action law was used to derive individual extraction constants for each amine allowing a mathematical description of the extraction behavior. This mathematical description provides a tool for the design of a tailor made reactive extraction system for the efficient recovery of amines while respecting given biotechnological pH requirements.

Individual extraction constants of some divalent metal cations in the two-phase water-phenyltrifluoromethyl sulfone system

Individual extraction constants of some divalent metal cations in the two-phase water-phenyltrifluoromethyl sulfone system

Individual Extraction Constants of Some Univalent Organic Cations in the Two-Phase Water–Phenyltrifluoromethyl Sulfone System

Abstract From extraction experiments and γ-activity measurements, the extraction constants corresponding to the general equilibrium C+(aq) + I−(aq) ⇔ C+(org) + I−(org) taking place in the two-phase water–phenyltrifluoromethyl sulfone (abbrev. FS 13) system (C+ = organic cation; aq = aqueous phase, org = FS 13 phase) were evaluated. Furthermore, the individual extraction constants of 8 univalent organic cations in the mentioned two-phase system were calculated.

Individual extraction constants of some univalent cations in the two-phase water–phenyltrifluoromethyl sulfone system

From extraction experiments and c-activity measurements, the exchange extraction constants corre- sponding to the general equilibrium M 2þ aq ðÞ þSr 2þ org ðÞ , M 2þ org ðÞ þSr 2þ aq ðÞ taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (M 2? = Mg 2? ,C a 2? ,B a 2? ,C u 2? ,Z n 2? ,C d 2? ,P b 2? , UO 2þ 2 ,M n 2? ,F e 2? ,C o 2? ,N i 2? ;a q= aqueous phase, org = FS 13 phase) were evaluated. Furthermore, the indi- vidual extraction constants of the M 2? cations in this two- phase system were calculated; they were found to increase in the series of Mg 2? ,UO 2þ 2 \ Ca

Individual extraction constants of some organic cations in the two-phase water–nitrobenzene system

From extraction experiments and c-activity measurements, the exchange extraction constants corre- sponding to the general equilibrium C ? (aq) ? Cs ? (nb) , C ? (nb) ? Cs ? (aq) taking part in the two-phase water- nitrobenzene system (C ? = organic cation; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Further- more, the individual extraction constants of 15 organic cations in the mentioned two-phase system were calculated.

Individual extraction constants of some divalent metal cations in the two-phase water–nitrobenzene system

From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M(aq) ? Sr(nb) ¢ M(nb) ? Sr(aq) taking part in the two-phase water– nitrobenzene system (M = Mg, Ca, Ba, Cu, Zn, Cd, Pb, UO2þ 2 , Mn , Fe, Co, Ni; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the individual extraction constants of the M cations in the mentioned two-phase system were calculated; they were found to increase in the following cation order: UO2þ 2 \ Zn , Ni \ Cu, Cd \ Co \ Mg \ Ca \ Mn, Fe \ Sr \ Pb \ Ba.

Interpretation by the Solvophobic Theory on the Linear Additive Representation of the Logarithm of Ion-Pair Extraction Constant with Individual Contributions of Cation, Anion, and Organic Solvent

A theoretical basis was given for the linear additive representation of the logarithm of ion-pair solvent extraction constant (Kex) in terms of logarithmic values of three individual extraction constants (Kcation, Kanion, and Ksolvent) for cations, anions, and organic solvents constituting ion-pair extraction systems. The differences in extractability between cations and between anions were quantitatively discussed according to the thermodynamic cycle model of 1:1 ion-pair extraction. The increment of log Kcation and log Kanion of hydrophobic ions is explained by taking the increment of the free energy change of the hydration (ΔGhyd) of the ions into account. The order of the extractability of inorganic cations and anions was also interpreted using literature data of ΔGhyd of each inorganic ion. The free energy change of the solvation of a hypothetical ion-pair having a shape of spherical was calculated on the basis of the solvophobic theory. The difference in extracting powers of some extracting organic ...

Individual extraction constants of some dicarbollylcobaltate anions in the water-nitrobenzene system

Individual extraction constants of nine dicarbollylcobaltate anions in the two-phase water-nitrobenzene system were determined radiometrically assuming that the changes of Gibbs energy of the transfer of the tetraphenylarsonium cation, Ph4As+, and of the tetraphenylborate anion, BPh 4 − , from the aqueous into the nitrobenzene phase are equal. The constants obtained by this method were correlated with Hansch's constants of hydrophobity.

The Extraction of Strontium and Barium with a Solution of Bis-1,2-Dicarbollylcobaltate in Nitrobenzene in the Presence of 18-Crown-6

A study has been made of the extraction of Sr and Ba in an aqueous solution of perchloric acid-18-crown-6-bis-1,2-dicarbollylcobaltate-nitrobenzene. It was found that the organic phase contains complexes of the ML2+org type ( M = Sr2+, Ba2+) that are converted to ML22+org when the concentration of crown (cL) is greater than the concentration of bis-1,2-dicarbollylcobaltate (cB). The values of the corresponding extraction constants, individual extraction constants and stability constants of the extracted species in the organic phase were determined. The system can be utilized for separation applications at concentrations here cL < cB.

The Extraction Transfer of H+-18-Crown-6 Species across the Water-Nitrobenzene Phase Boundary in the Extraction of Aqueous Solutions of Perchloric Acid by Nitrobenzene in the Presence of 18-Crown-6

A study was made of the extraction of perchloric acid in water-nitrobenzene-18-crown-6 (hereafter L) systems. The experimental data was interpreted on the basis of the assumption that the extraction occurs according the equations H+aq + ClO4,aq- ↔ H+org + ClO4,org- and H+aq + Laq + ClO4,aq- ↔ HL+org + ClO4,org-. Crown is also protonated in the aqueous phase according to the equation H+aq + Laq ↔ HL+aq. The values of the corresponding extraction constants, the protonation constants of 18-crown-6 in nitrobenzene and water and the individual extraction constants of the HL+ species in the water-nitrobenzene system were determined, along with the magnitude of the molar free enthalpy for the transfer of these species across the given phase boundary.

EXTRACTION SYSTEMS USING BIS-1,2-0ICARBCILYLC0BALTATE ANO POLYOXONIUM COMPOUNDS FOR LANTHANIOE SEPARATIONS

ABSTRACT The extraction of rare earths (lanthanides, Y, Sc) by voluminous bis-1,2-dicarbollylcobaltate anions disolved in nitrobenzene and in a nitrobenzene - carbon tetrachloride mixture has been investigated and the exchange extraction constants for both solvents, individual extraction constants anddG for ion transfer across the water - nitrobenzene phase boundary has been determined. Extraction decreases with increasing atomic number of the lanthanide. The influence of several polyoxonium compounds on the distribution ratios and the extraction selectivity has been investigated. In the extraction systems with bis-1,2-dicarbollylcobaltate - 18-crown-6 in nitrobenzene, synergism was found for the light lanthanides but antagonism was observed for the heavy ones. The overall separation factor is Ctla/10 compared to in the absence of crown la/2

Thermodynamic parameters characterizing complexes of alkali metal cations with dibenzo-24-crown-8 in the water—nitrobenzene extraction system

By using known thermodynamic parameters, the Briggs logarithms of the individual extraction constants for the ML + complex cations (M + = Na +, K +, Rb +, Cs +; L = dibenzo-24-crown-8) in the water—nitrobenzene extraction system at 25 C have been evaluated. It has been found that these constants increase in the order Na + < K + < Rb + < Cs +, i.e. in the order of increasing crystallographic radii of the alkali metal cations.

Contribution to the thermodynamics of complexes of alkali metal cations with dibenzo-18-crown-6 in water-nitrobenzene extraction system

The stability constants for the ML+ complex species, where M+ is an alkali metal cation and L is dibenzo-18-crown-6, in nitrobenzene saturated with water were calculated by employing published equilibrium data. The stability is found to increase in the cation order Li+ &lt; Cs+ &lt; Rb+ &lt; K+ &lt; Na+. For the NaL+, KL+, RbL+, and CsL+ complex cations the individual extraction constants in the water-nitrobenzene system were determined; their values increase in the series Na+ &lt; K+ &lt; Rb+ &lt; Cs+.

The distribution of cerium (III) cations between aqueous and nitrobenzene phases in the presence of dicarbolide anions

Extraction of micro- and macroquantities of Ce 3+ (C° Ce = 10 6−−10 −1 mole/dm 3) with a nitrobenzene solution of dicarbolide (C° H +B − = 0.04−0.5 mole/dm 3) from a nitric acid solution (C° HNO 3 = 0.1−0.3 mole/dm 3) was investigated. Coextraction of water and simultaneous extraction of Ce 3+ and Ba 2+ ( C Ce + + C Ba = 0.3 mole/dm 3) from 0.3 and 0.5 M HNO 3 was also studied. It was found that the reaction Ce 3+ + 3H̄Ce⇌ 3+ + 3H (K Ce/3H) takes place in all cases. The dependence of the apparent exchange extraction constant K Ce/3H on the initial composition of both phases was determined and the effect of the composition of the aqueous phase on the values of K Ce/3H and K Ba/2H was discussed. The stability constant of the CeNO 2+ 3 complex and the hydration number of the Ce 3+ cation in the organic phase (h 3+ Ce = 16.2 ± 2) was determined and a linear correlation between individual extraction constants of mono-, bi- and trivalent cations and the hydration numbers in the nitrobenzene phase was found using data from the present paper and values given in literature.

Extraction constants of ion-pairs

It is assumed that the extraction constant, Kex, for the ion-pair extraction systems is made up of three independent constants (individual extraction constants), Ke, Ka and Ks, in accordance with the equation:log Kex=logKe+logKa+log Kswhere the subscripts c, a, and s denote cation, anion, and solvent, respectively. Log K values for several cations, anions, and solvents were calculated from experimental values of log Kex by tentatively assigning the log K values 1.0 and 0.0 to perchlorate and benzene, respectively, as reference values. The cations, anions and the solvents studied were Co (III) complexes of three 2-(2-pyridylazo)-5-diethylaminophenols, perchlorate and three anionic surfactants, and benzene, toluene, and chlorobenzene. The above equation is shown to be useful in estimating the unknown value of Kex from the constants assigned to each ion and the solvent.

The distribution of barium cations between aqueous and nitrobenzene phases in the presence of dicarbolide anions

The extraction of Ba 2+ from HNO 3 solutions into nitrobenzene containing H + [π-(3)-1,2-B 9C 2H 11] 2Co − was studied. The data obtained obey the exchange reaction Ba 2+ + 2H org + = Ba org 2+ + 2H + with log K Ba/2H = 0.67 to 0.94 for c HNO 3 ≤ 1 mole/1. The hydration of Ba 2+ ion in the nitrobenzene phase was determined experimentally. The average hydration number is h Ba 2+ = 11.5 ± 1. The individual extraction constants for the alkali and alkaline earth cations correlate well with their respective hydration numbers.

Individual extraction constants of univalent ions in the system water-nitrobenzene

Individual extraction constants of univalent ions in the system water-nitrobenzene