Comparative Study on Reactive Extraction of Picolinic Acid with Six Different Extractants (Phosphoric and Aminic) in Two Different Diluents (Benzene and Decan-1-ol)

The equilibrium study on reactive extraction of picolinic acid by six different extractants (phosphoric and aminic) dissolved in two different diluents (benzene and decane-1-ol) is carried out to evaluate the performance of extractants and diluents. The extraction ability in terms of the distribution coefficient (K _D) is found to be in the order of tri-n-octylamine (TOA) ≥ tri-n-dodecylamine (TDDA) > di-2-ehylhexyl phosphoric acid (D2EHPA) > tri-n-butyl phosphate (TBP) > tri-octyl methyl ammonium chloride (Aliquat 336) > tri-n-octyl phosphine oxide (TOPO) with both diluents. Decan-1-ol is found to be the better solvating medium for the acid-extractant complexes. A mathematical model based on mass action law is employed to estimate the values of partition coefficient (P) and dimerization constant (D) in physical extraction, and equilibrium extraction constants (K _E) in chemical extraction. The values of loading ratios (Z) less than 0.5 imply the formation of (1:1) acid:extractant solvates in the organic phase. Decan-1-ol with TOA is the most effective solvation medium with K _{D, max} = 9 at 0.01 kmol · m^?3 of picolinic acid and K _E = 19.448 m³ · kmol^?1.     

Solvent Extraction of Li+ using Organophosphorus Ligands in the Presence of Ammonia

In this work, the selective extraction of Li⁺ with the aid of organophosphorus ligands (H-OP) including phenylphosphonic (H-PHO), phenylphosphinic (H-PHI) and bis(2-ethylhexyl) phosphoric (H-BIS) acids in the absence and presence of ammonia was studied. Adding NH₃ to the aqueous phase resulted in significant improvement in the % extraction of Li⁺ into the organic phase containing H-OP ligands. The highest % extraction values obtained in the case of H-PHO, H-PHI, and H-BIS were 43.2%, 45.7%, and 90.0%, respectively. Two mechanisms were inferred; the first was that the extraction equilibrium reaction of LiCl + H-OP ? Li-OP + HCl shifted forward due the reaction of the produced HCl with NH₃. The second mechanism was that the Li⁺/NH₄⁺ exchange of NH₄-OP (produced from the reaction of H-OP with NH₃) was easier than Li⁺/H⁺ exchange of H-OP itself. Competitive extraction experiments indicated that the selectivity factors of Li⁺ over Na⁺ and K⁺ were strongly dependent on the concentration of H-OP ligands which suggested that aggregation of ligand molecules via hydrogen bonding is the limiting factor for selectivity.     

Reactive Extraction of Pyridine Carboxylic Acids with N,N-Dioctyloctan-1-Amine: Experimental and Theoretical Studies

The paper represents the equilibrium study on reactive extraction of pyridine-3-carboxylic acid (NA) and pyridine-4-carboxylic (iNA) acid from aqueous solution by N, N-dioctyloctan-1-amine (TOA) dissolved in five different diluents [dodecane, methyl benzene, decan-1-ol, 4-methylpentan-2-one (MIBK), and chloroform] at constant temperature of 298 ± 1 K. According to an experimental study, the extraction ability of diluents with TOA is found to be in the order of chloroform > decan-1-ol > MIBK > methyl benzene > dodecane for both acids. The highest extraction efficiency in terms of the distribution coefficient (K _D) is found to be 45.15 and 25.79 for NA (0.12 mol · dm^?3) and iNA (0.03 mol · dm^?3), respectively. The values of loading ratio, Z (between 0.194 and 0.512) for both acids indicate the formation of 1:1 acid-TOA complexes in the organic phase. The values of the equilibrium constants (K ₁₁) are determined from the experimental data using mass action law. These estimated values of K ₁₁ are compared with the predicted values of K ₁₁ from relative basicity and linear solvation energy relationship (LSER) models. The LSER model predicts the K ₁₁ with an error limit of ±3% for NA and ±2% for iNA.     

Reactive separation of p-nitro phenol (PNP) from aqueous solution using tri-n-butyl phosphate: equilibrium and COSMO-RS studies

ABSTRACT

The present study is aimed to optimized diluent type, tri-n-butyl phosphate (TBP) composition and temperature for the reactive extraction of p-nitro phenol (PNP) in two different PNP concentration ranges [(0.00036–0.00646) kmol·m^?3 and (0.00646–0.01437) kmol·m^?3] as found in industrial effluents. 1-Octanol is investigated as the best diluent with TBP based on COSMO-RS theory. Equilibrium study based on mass action law is performed to find the insights of extraction mechanisms, equilibrium constant (K = 295.12 k·mol^?1) and stoichiometry (m:n = 1:1) as also confirmed by FTIR. Thermodynamic parameters, enthalpy (ΔH°), and entropy (ΔS°) are determined 27.51 K J mol^?1 and ?50.21 J mol^?1 K^?1, respectively.     

Synergistic Extraction of Trivalent Actinides by Mixtures of 1-Phenyl-3-methyl-4-benzoyl-pyrazolone-5 and Neutral Oxo Donors

Abstract

The synergistic extraction of trivalent actinides Am, Cm, Bk, and Cf with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and TBP or TOPO has been investigated in xylene at 30°C. With HPMBP alone, all four trivalent actinides form M(PMBP)₃· HPMBP-type self-adducts. Bk(III) shows an abnormally high extraction with HPMBP alone. With TBP or TOPO(S) as neutral donor, except in the Bk/HPMBP/TBP system where Bk(PMBP)₃· HPMBP·TBP was extracted, all metal ions were extracted as M(PMBP)₃·S and M(PMBP)₃·(S)₂ into the organic phase. The equilibrium constants (β₁, β₂, and K ₂ for the organic phase synergistic reactions have been calculated. The β₁, β₂ values for Bk(III)/HPMBP/TOPO system are much lower as compared to the corresponding values for other trivalent actinides. The reasons for this extraordinary behavior of Bk(III) have been discussed. The extraction behavior of the M(III)/HPMBP/S and the M(III)/HTTA/S systems has also been compared.     

Kinetics of Solvent Extraction of Iron(III) from Sulfate Medium by Purified Cyanex 272 using a Lewis Cell

Abstract

The kinetics of the forward and backward extraction of the title process have been investigated using a Lewis cell operated at 3 Hz and flux or (F) – method of data treatment. The dependences of (F) in the forward extraction on [Fe³⁺], [H₂A₂]_(o), pH, and [HSO₄ ^?] are 1, 0.5, 1, and ?1, respectively. The value of the forward extraction rate constant (k _f ) has been estimated to be 10^?7.37 kmol^3/2 m^?7/2 s^?1. The analysis of the experimentally found flux equation gives the following simple equation: F _f =10^0.13 [FeHSO₄ ²⁺] [A^?], on considering the monomeric model of BTMPPA and the stability constants of Fe(III)‐HSO₄ ^? complexes. This indicates the following elementary reaction occurring in the aqueous film of the interface as rate determining: [FeHSO₄]²⁺+A^?→[FeHSO₄.A]⁺. The very high activation energy of 91 kJ mol^?1 supports this chemical reaction step as rate-determining. The negative value of the entropy change of activation (?94 J mol^?1 K^?1) indicates that the slow chemical reaction step occurs via the S_N2 mechanism.

The backward extraction rate can be expressed by the equation: F _b =10^?5.13 [[FeHSO₄A₂]]_(o) [H⁺] [H₂A₂]_(o) ^?0.5. An analysis of this equation leads to the following chemical reaction step as rate-determining: [FeHSO₄A₂]_(int)→[FeHSO₄A]+A_(i) ^?. However, the activation energy of 24 kJ mol^?1 suggests that the backward extraction process is intermediate controlled with greater contribution of the diffusion of one or the other species as a slow process. The equilibrium constant obtained from the rate study matches well with that obtained from the equilibrium study.     

Extraction Equilibria of 4-Hydroxypyridine using Di (2-ethylhexyl) Phosphoric Acid

Extractions of 4-Hydroxpyridine (4HP) from aqueous solutions using Di(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant in 1-octanol and kerosene were studied. The factors that affected the distribution coefficient (D), such as equilibrium pH, the concentration of D2EHPA, and the type of diluents were discussed. The interaction mechanism between 4HP and D2EHPA was validated by infrared spectroscopic analysis. D increased with the increase of the concentration of D2EHPA and peak values appeared at equilibrium pH = 3.6–5.0. D in the polar diluent (1-octanol) was much higher than those in the non-polar diluent (kerosene). The extraction reaction was found to be a proton-transfer process and D2EHPA mainly reacted through its –OH with –N– of 4HP. The apparent reactive extraction equilibrium constants K ₁₁ and K ₁₂ were obtained by fitting the experimental data of extraction equilibrium. By comparing calculated D values from the proposed model with the experimental ones, the accuracy of the proposed model was examined.     

The Solvent Extraction of Heptavalent Technetium by Tributyl Phosphate

Abstract

The solvent extraction of heptavalent technetium from aqueous nitric or hydrochloric acid by tributyl phosphate in n-dodecane (TBP-NDD) has been studied over a wide range of TBP and acid concentrations at 25, 50, and 60°C. The extraction was found to proceed according to the reaction 3TBP + H⁺ + TcO₄ ^? → (HTcO₄ · 3TBP). A discussion of possible reaction mechanisms is presented, along with values for ΔG, ΔH, ΔS, and the equilibrium constant for the extraction reaction. Finally, evidence for the coextraction of technetium by uranyl ions is discussed.     

Synergistic interplay between D2EHPA and TBP towards the extraction of lithium using hollow fiber supported liquid membrane

Extraction of lithium (Li⁺) from synthetically prepared sea bittern using di-2-ethyl hexyl phosphoric acid (D2EHPA) and tri-n-butyl phosphate (TBP) as organic extractants has been studied. The equilibrium studies conducted show synergistic effect between D2EHPA and TBP. The equilibrium constant values for Li⁺, Na⁺ and K⁺ ions were found to be 95.4 × 10^?5 m³/kmol, 4.6 × 10^?5 m³/kmol and 3.69 × 10^?5 m³/kmol, respectively. Hollow fiber supported liquid membrane (SLM) experiments with low concentrations of Li⁺, Na⁺ and K⁺ ions in feed phase showed high flux for Li⁺ ions. However, at significantly high concentrations of Na⁺ and K⁺ in the feed phase, the flux of Li⁺ ions reduced. The model predictions were found to be in good agreement with the experimental data.     

Dissociation et hydratation de nitrates alcalins dans le carbonate de propylene aqueux

Dissociation of lithium, sodium, potassium and tetraethylammonium nitrates and perchlorates in propylene carbonate has been studied by conductometry. Dissociation constants of alkali nitrates are 3·14 × 10^?3 (LiNO₃), 8·35 × 10^?3 (NaNO₃ and 1·92 × 10^?2 (KNO₃) at 25°C. The perchlorates and tetraethylammonium nitrate are strong electrolytes. The solubility products are 4·1 × 10^?4 (LiNO₃), 1·2 × 10^?5 (NaNO₃ and 2·5 × 10^?5 (KNO₃). The conductivity of saturated solutions of nitrates in the aqueous solvent has been determined up to 0·6 M water. Results are used to calculate the equilibrium constants for the reaction I^± + H₂O = I^± H₂O; Li⁺ 6·5, Na⁺ 2·5, K⁺ 0·5 and NO^?₃ 2·4. Dissociation constants, solubility products and hydration constants are compared with values reported for other solvents.     

Reactive Extraction of Formic Acid by using Tri Octyl Amine (TOA)

Abstract

Distribution of formic acid (methanoic acid) between water and tri octyl amine (TOA) dissolved in various alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, decan-1-ol) as diluents, as well as the extraction capacity of pure diluent alone have been studied at isothermal conditions. All measurements were carried out at 298.15 K. The difference between the physical extraction and reactive extraction was studied. The loading factor, T _T, extraction efficiency, D _E, modified separation factor, S _F, and, distribution coefficients, K _D were calculated. The isoamylalcohol was found most effective solvent with maximum distribution value of 14.521. Possible equilibrium complexation constants for (acid:amine) (5:1), (6:1), and (7:1) have been determined as values of about 21.8 × 10³, 15.6 × 10⁴, and 11.1 × 10⁵ for K₅₁, K₆₁, and K₇₁, respectively with isoamylalcohol. Furthermore, Linear Solvation Energy Relationship (LSER) model equation has been obtained to calculate distribution coefficients for alcohols with regression coefficient of 0.981.     

Extraction Theory and Form of the Extraction Complex for the Metals Dysprosium,Holmium, Thulium,and Curium in the Synergistic System Kerosene/HTTA/TBP/Dilute HNO3

Abstract

Data were taken for the distribution of HTTA and the metals Dy, Ho, Tm, and Cm in the system kerosene/thenoyltrifluoroacetone (HTTA)/tributylphosphate (TBP)/dilute HNO₃. The theory first proposed by Tournier (1) and Tournier and Davis (2) for the HTTA distribution was modified and new values of the equilibrium constants resulting from the theory were determined by a least squares fit of the HTTA distribution data. The new values are K ₁ = 14 and K ₂ = 3.45.

An analysis of the HTTA distribution data indicates that one molecule of TBP associates with one molecule of (HTTA·H₂O) to form a complex. Analysis of distribution data for the metals, Dy, Ho, Tm. and Cm using the modified theory indicates that the form of the metal complex is M⁺³(TTA)₃(TBP)₂ reported by most investigators.

A log-log plot of q o/a as a function of [H⁺] under conditions of constant free TBP and HTTA and constant ionic strength indicates an inverse squared effect of [H⁺] on the metal distribution ration, q o/a. This in turn supports the indications that two (TTA) molecules are associated with the metal complex. No experimental data to verify the presence of (NO₃ ^?) in the complex have as yet been obtained.     

Ketone Extraction of Mixed Chloride-Bisulfate Complexes of Aluminum

Abstract

The partition ratio D of Al(III) between aqueous chloride/bisulfate solutions of constant ionic strength (5.0) and methyl ethylketone (MEK) or methyl isobutyl ketone (MIBK) was investigated radiometrically as a function of the chloride/bisulfate ratio and aqueous acidity. With MIBK, the plot of D vs chloride/bisulfate showed a maximum. Results may be explained by assuming the extraction of the following species: KtH⁺·AlCl₄-, KtH⁺-AlCl₂(HSO₄)₂- and KtH⁺·Al(HSO₄)₄, where KtH⁺ represents a solvated hydrogen ion. Formation constants for these complexes were calculated.     

Separation of Simulated Mixed Mo(VI) and V(V) From HNO3 and HCl Solutions by Selective Extraction and Stripping with Tri-N-Butyl Phosphate as Extractant

Equilibrium study was carried out to determine the optimum conditions required for Mo(VI) extraction from HNO₃ solutions and subsequently, simulated mixed Mo(VI), and V(V) were extracted from HNO₃ (pH = 1.0) and 6.0 mol L^?1 HCl solutions with TBP dissolved in n-hexane. The variation of pH (selective extraction) and selective stripping were investigated as methods of separation of Mo(VI) and V(V). The latter method was found inefficient for separations from HNO₃ solutions (pH = 1.0) except supplemented with selective stripping (back-extraction with 2.0 mol L^?1 H₂SO₄/14.5 mol L^?1 NH₄OH). While from 6.0 mol L^?1 HCl, selective stripping was adequate to quantitatively strip in turns the Mo(VI) and V(V) co-extracted into the TBP phase. About 100% of the co-extracted V(V) from the HCl medium was stripped in a two-stage process, in contrast to a single-stage required for Mo(VI) of the same result. The selective stripping method was found to be better because an initial appreciable co-extraction had occurred prior to stripping separation. Based on analytical and spectra data, the extracted complexes from HNO₃ and HCl media were formulated as ((MoO₂)_7–8n(VO₂)_2n · (NO₃)₁₆) ^(16–18)n- · m TBP (where n>m) and (MoO₂Cl₂ · VO₂ Cl) · xTBP, respectively.     

SELECTIVE EXTRACTION OF PALLADIUM(II) FROM CHLORIDE SOLUTIONS WITH NONYLTHIOUREA DISSOLVED IN CHLOROFORM

ABSTRACT

The extraction of Palladium(II) [Pd(II)] from hydrochloric acid solutions with nonylthiourea (NTH) dissolved in chloroform at a constant ionic strength of 1.0?M has been studied. The extraction of Pd(II) has been investigated as a function of the concentration of the extractant, chloride ion, and proton concentrations as well as extraction temperature. The distribution data have been treated graphically and numerically. The analysis of the experimental data has shown that Pd(II) is extracted as PdCl₂·(NTH) and PdCl₂·(NTH)₂ species with the respective extraction constants of log?K ₁₁=5.0±0.1 and log?K ₁₂=9.1±0.1. The back-extraction of Pd(II) from the organic phase using different stripping reagents has been examined. The selectivity of NTH for Pd(II) against Pt(IV), Rh(III), Cu(II), Fe(III), and Zn(II) has also been investigated.     

Complete Li+ exchange into zeolite X (FAU, Si/Al = 1.09) from undried methanol solution

Complete exchange of Li⁺ into zeolite Na-X, |Na₉₂|[Si₁₀₀Al₉₂O₃₈₄]-FAU, was accomplished using undried methanol solvent (water concentration 0.02 M). A crystal of Na-X was treated with 0.1 M LiNO₃ in the solvent at 333 K, followed by vacuum dehydration at 673 K and 1 × 10^?6 Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group $ Fd\overline{3} $ at 100(1) K. The 92 Li⁺ ions per unit cell are found at three different crystallographic sites. The 32 Li⁺ ions occupy at site I’ in the sodalite cavity: these Li⁺ ions are recessed 0.28 Å into the sodalite cavity from their 3-oxygens plane [Li–O = 1.903(5) Å and O–Li–O = 117.8(3)°]. Another 32 Li⁺ ions are found at site II in the supercage, being recessed 0.26 Å into the supercage [Li–O = 1.968(5) Å and O–Li–O = 118.3(3)°]. The remaining 28 Li⁺ ions are located at site III in the supercage [Li–O = 2.00(8) Å].     

Estimation of equilibrium parameters using differential evolution in reactive extraction of propionic acid by tri-n-butyl phosphate

The graphical and conventional optimization methods, used for the estimation of equilibrium parameters, do not guarantee the global optimum values. In this study, the equilibrium parameters are estimated using a well proven evolutionary based optimization routine [differential evolution (DE)]. For the estimation of stoichiometry and equilibrium constants, experiments are carried out for the reactive extraction of propionic acid using tri-n-butyl phosphate (TBP) dissolved in n-decane (inert diluent) and 1-decanol (modifier). The number of TBP molecules (n) in the acid:TBP complex and equilibrium extraction constant (K_E) using 1:1 volume ratio of 1-decanol and n-decane as a diluent, are determined through proposed mathematical model using graphical methods as well as the differential evolution algorithm (DE, an optimization routine) and found that the predicted values of distribution coefficient (K_D) using DE are closely matching with the experimental values of K_D. 1:1 complexes between TBP and acid are formed in most of the cases. The enthalpy and entropy of reactive extraction of propionic acid using TBP are also determined and found to be −12.47 kJ mol⁻¹ and −32.42 J mol⁻¹ K⁻¹, respectively. The results of present study will be useful to intensify the recovery of propionic acid from fermentation broth (bio-separation) and aqueous waste stream.     

Investigations on the Reactive Extraction of Glyoxylic Acid by Amberlite-LA2 Dissolved in Alcoholic Diluents

In this study, reactive extraction of glyoxylic acid (0.93 kmol·m^?3) using Amberlite-LA2 (0.24 to 1.67 kmol·m^?3) in five different alcoholic diluents is performed at 298 K. The extraction ability of Amberlite-LA2 is found to be in the order of isoamylalcohol (IAA) > nonan-1-ol > octan-1-ol > decan-1-ol > dodecanol. Maximum extraction efficiency, 98.92% is obtained at 1.67 kmol·m^?3 of Amberlite-LA2 in IAA. The values of stoichiometric coefficient (m), overall equilibrium constant (K_E) and individual constants (K₁₁, K₂₁, and K₁₂) are estimated. The effect of diluent on K_D is also quantified by applying LSER model using solvatochromic parameters of diluents.     

Separation of Carrier Free 90Y from 90Sr by Hollow Fiber Supported Liquid Membrane Containing Bis(2-ethylhexyl) Phosphonic Acid

The present article gives a comparative account of the efficiency of carrier-free ⁹⁰Y separation from ⁹⁰Sr by solvent extraction, flat sheet-supported liquid membrane (FSSLM) and hollow fiber-supported liquid membrane (HFSLM) methods using bis(2-ethylhexyl) phosphonic acid (PC88A) as the carrier extractant. The major focus of this work has been to develop the HFSLM method for the separation of Y(III) on a relatively large scale. The feed and receiver phase conditions were optimized by carrying out batch solvent-extraction studies. The extraction of Sr(II) by PC88A was negligible in the acidity range of 0.01–3 M HNO₃, whereas the extraction of Y(III) was significantly large at lower acidity (≤0.1 M HNO₃) with a separation factor (SF = D_Y/D_Sr) of 8.5 × 10⁴. HFSLM studies suggested selective and efficient transport of Y(III) into 3 M HNO₃ from a feed solution containing a mixture of Y(III) and Sr(II) at 0.1 M HNO₃. On the other hand, transport of Sr(II) was negligible in the receiver phase. The purity of the separated ⁹⁰Y was ascertained by paper chromatography and by half-life measurement. The radiation stability of the carrier was excellent as studied up to 1000 KGy dose.     

The Kinetics of Melting Crystallization of Poly-L-Lactide

The influence of non-isothermal melt crystallization on thermal behavior and isothermal melt crystallization kinetics of poly-L-lactide (PLLA) were investigated by differential scanning calorimetry (DSC), polarizing micrograph (POM) and x-ray diffraction (XRD). Crystallization performed at lower cooling rates (2°C·min^?1) is accompanied by a variation of the kinetics around 118°C. The glass transition temperature of PLLA decreases with increase of cooling rate, and the crystallinity at the end of crystallization increases with decreasing cooling rate. The size of PLLA spherulites increases with a decrease in the cooling rate, and PLLA becomes almost amorphous cooled at rapid rate (>10°C·min^?1). PLLA exhibits an Avrami crystallization exponent n = 3.01±0.13 in isothermal crystallization in the range from 90°C to 140°C. According to Hoffman-Lauritzen theory, two crystallization regime are identified with a transition temperature occurring at 118°C, and the value of K_g(II)/K_g(III) is 2.17 [K_g(II) = 6.025 × 10⁵K², K_g(III) = 1.307 × 10⁶ K²].