Extraction equilibrium of m-cresol by tri-n-octylamine sulfate salts

The influence of the extraction conditions on the distribution coefficient of m-cresol were investigated. The equilibria of m-cresol extraction from an aqueous solution by the tri-n-octylamine sulfate salts (TOA salts) in an organic solvent were examined. Sulfuric acid first reacted with tri-n-octylamine (TOA) to form TOA salts; then m-cresol was extracted into the organic phase from the aqueous phase by the TOA salts. The model of the equilibrium of the chemical reaction of TOA and sulfuric acid to form the TOA salts was constructed by modifying the Wilson model (Wilson, 1967). The predictions of the developed model were fairly consistent with the experimental data, and it was applied to the reaction systems in benzene at various temperatures to predict the extraction of m-cresol. The number of water molecules associated with the various TOA salts, which reflect the extraction capability of m-cresol, was determined.     

Equilibrium studies on reactive extraction of lactic acid with an amine extractant

Equilibrium studies on the extraction of lactic acid from aqueous solutions with tri-n-octylamine (TOA) in xylene were made in the temperature range 293–323 K. The formulation of the extracted species in the organic phase and the corresponding equilibrium constants were numerically determined at different temperatures. Also, the apparent thermodynamic functions were calculated. Finally, the effect of a water-insoluble organic acid, di(2-ethylhexyl)phosphoric acid (D2EHPA), on this extraction was investigated. Synergistic and antagonistic effects were observed in the presence of D2EHPA, mainly depending on the concentration ratio of D2EHPA to TOA.     

Synergistic Extraction of Some Rare Earths(III) from Nitrate Media by Thenoyltrifluoroacetone and Tri-n-octylamine

Abstract

The synergistic action of tri-n-octylamine (TOA) in the selective extraction of the rare earths La, Nd, Tm, Lu, and Y with thenoyltrifluoroacetone (HTTA) was studied in a nitrate media (0.6 M HNO₃ + 11.6 g/L CaO). The synergism enhances the REE extraction and separation. The [HTTA], [TOA], diluent, complexing agents, and calcium ion effects were also studied.     

Efficacy of tri-n-octylamine,tri-n-butyl phosphate and di-(2-ethylhexyl) phosphoric acid for reactive separation of protocatechuic acid

ABSTRACT

Owing to its chemical and pharmacological significances, the efficacy of reactive separation of protocatechuic acid (0.001–0.01 kmol m^?3) from aqueous stream by means of tri-n-octylamine (TOA), di-2-ethylhexyl phosphoric acid (D2EHPA) as well as tri-n-butyl phosphate (TBP) in octanol has been investigated, in terms of extraction efficiency, loading ratio, equilibrium complexation constants, and distribution coefficients. Extraction ability was obtained in the order TOA (91.2%) > TBP (88.64%) > D2EHPA (86.43%). In all cases, 1:1 protocatechuic acid:extractant complex is obtained. Further, diffusion coefficients, number of stages for extraction systems, and relative basicity model were used for relating the efficacy.     

INFLUENCE OF SOLVENT POLARITY ON INTERFACIAL MECHANISM AND EFFICIENCY OF SUCCINIC ACID REACTIVE EXTRACTION WITH TRI-n-OCTYLAMINE

This article presents the results of a comparative study of reactive extraction of succinic acid with tri-n-octylamine (TOA) dissolved in solvents with different dielectric constants (dichloromethane, n-butyl acetate, and n-heptane), with and without octan-1-ol addition as phase modifier. The positive effect of octan-1-ol on extraction efficiency was quantified by means of amplification factors. For all studied systems, the addition of octan-1-ol into the solvent phase led to an increase of extraction efficiency, the most important effect being recorded for the solvent with the lowest polarity, namely n-heptane. The maximum value of amplification factor was reached for pH = 6 and indicated an increase of reactive extraction yield of about 1.26 times for dichloromethane, 1.55 times for n-butyl acetate, and 2.88 times for n-heptane.     

Extraction of Uranium from “Abu-Tartur” Phosphate Aqueous Leachate Solution

Abstract

Uranium was effectively extracted from a synthetic aqueous monocalcium phosphate/phosphoric acid mixture (MCP/H₃PO₄) by tri-n-octylamine dissolved in different solvents and the presence of low concentrations of some counteranions (oxalate, citrate, chloroacetate) in the aqueous phase. The extraction efficiency was markedly enhanced by the salting out action of the concentration of calcium ions in the MCP/H₃PO₄ solution.     

Extraction–electrodeposition (EX–EL) process for the recovery of palladium from high-level liquid waste

Extraction–electrodeposition (EX–EL) process has been developed for the quantitative recovery of palladium from nitric acid medium and fast reactor-simulated high-level liquid waste (FR-S-HLLW). The process exploits some characteristic properties of room temperature ionic liquid, tri-n-octylmethylammonium nitrate (TOMAN), for quantitative and favorable recovery of palladium. Extraction of palladium (II) from FR-S-HLLW and nitric acid medium by a solution of 0.5 M TOMAN in chloroform has been studied in detail. More than 60% of palladium was extracted in a single contact of equal volumes of organic and aqueous phases and nearly five contacts were required for quantitative extraction. The electrochemical behavior of palladium (II) present in the organic phase was investigated at stainless steel electrode by cyclic voltammetry. A surge in cathodic current occurring at a potential of –0.5 V (vs. Pd) was due to the reduction of palladium (II) to palladium (0). The kinetics of electrodeposition was followed by the UV–VIS absorption spectrum of palladium present in organic phase and under the given conditions nearly 20 and 35 h were required for the quantitative deposition of palladium from organic phase, which was obtained after extraction of palladium from 4 M nitric acid and FR-S-HLLW, respectively. Decontamination of palladium from other fission products during extraction and electrodeposition was studied and the results are reported in this article.     

Reactive extraction of succinic acid using supercritical carbon dioxide

Reactive extraction using supercritical carbon dioxide (scCO₂) and tri-n-octylamine (TOA) was evaluated as a separation method of succinic acid from an aqueous solution. The reactive extraction of succinic acid was performed at varying initial acid concentrations in aqueous solution (0.07–0.45 mol?dm^?3), temperature (35–65°C) and pressure (8–16 MPa). The succinic acid separation was conducted in both batch mode and semi-continuous mode. The highest reactive extraction efficiency of approx. 62% was obtained for the process conducted in semi-continuous mode at 35°C and 16 MPa for the initial acid concentrations in aqueous phase of 0.39 mol?dm^?3.     

Effect of a water-insoluble organic acid on amine extraction of acetic acid from aqueous solutions. Equilibrium studies

The effect of a water-insoluble organic acid, di(2-ethylhexyl)phosphoric acid (D2EHPA), on the extraction equilibrium of acetic acid from aqueous media with xylene solutions of tri-n-octylamine (TOA) was systematically investigated. In the absence of D2EHPA, the formulation of the extracted species in the organic phase and equilibrium constants for the formation of these species were numerically determined. Synergistic and antagonistic effects on the extraction of acetic acid were observed in the presence of D2EHPA, mainly depending on the concentration of TOA and the concentration ratio of D2EHPA to TOA. Finally, the influence of temperature on the extraction of acetic acid with TOA and/or D2EHPA was investigated.     

Effect of Br− on the Adsorption Rate of Palladium(II) Ions onto Condensed-Tannin Gel in Chloride Media

Abstract

In chloride media, chloropalladium(II) species are adsorbed onto tannin gel particles through an inner-sphere redox reaction mechanism containing the intermediate step, formation of a ligand-substituted Pd(II)-tannin complex. In this Pd(II) adsorption process, it was observed that the adsorption rate can be increased by introducing Br^?, a softer ligand than Cl^?, into the aqueous chloride solution. The formation of mixed-ligand palladium(II) complexes accelerates the rate of ligand-substitution reactions with the hydroxyl groups of tannin gel by the trans effect. The adsorption condition can be optimized by controlling the [Br_tot]/[Cl_tot] ratio, in which the predominant Pd(II) species are bromo-chloro palladium(II) complexes, the favorable species for the trans effect.     

Adsorption Behaviors of Platinum Group Metals in Simulated High Level Liquid Waste Using Macroporous (MOTDGA-TOA)/SiO2-P Silica-based Absorbent

As fundamental research for separation of platinum group metals (PGMs) from high level liquid waste (HLLW) by macroporous silica-based adsorbent, (MOTDGA-TOA)/SiO₂-P adsorbent was prepared by impregnation of N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (MOTDGA) and Tri-n-octylamine (TOA) into silica/polymer composite support (SiO₂-P). The adsorption behavior of Ru(III), Rh(III), and Pd(II) in simulated HLLW onto the adsorbent were investigated by the batch method to obtain their corresponding equilibrium and kinetic data. The adsorbent showed strong adsorption for Pd(II) and the adsorption reached equilibrium within 2 hr. High distribution coefficient (K _d) values for Pd(II) were obtained in 0.1–1 M HNO₃ concentration. In addition, the use of both MOTDGA and TOA improved adsorption of Ru(III) and Rh(III) better than individual use of them. Especially, the K _d value for Ru(III) towards (MOTDGA-TOA)/SiO₂-P adsorbent was three times larger than that in the adsorption using only with MOTDGA or TOA as extractant. The adsorptions of Ru(III), Rh(III), and Pd(II) followed the Langmuir adsorption model, and were found to be controlled by the chemisorption mechanism.     

Synergistic Extraction of Rhodium(III) from Hydrochloric Acid Solution with Tri-n-octylamine and Sulfide-type Extractants

Synergistic extraction of Rh(III) from relatively concentrated HCl solution was studied using two mixed solvents (di-n-hexyl sulfide (DHS)–tri-n-octylamine (TOA) and N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (TDGA)–TOA) in chloroform. The Rh(III) extraction efficiency is poor when 0.5 M TOA, DHS, or TDGA is used independently. In contrast, the 0.5 M TDGA–0.5 M TOA and 0.5 M DHS–0.5 M TOA mixed solvents extract ?90% and ?70% of Rh(III), respectively, at maximum. Slope analyses and Job’s plots for the distribution ratios of Rh(III) at 2 M HCl show that the apparent stoichiometry of Rh(III):TOA:(DHS or TDGA) in the extracted complex is 1:2:1.     

Highly Efficient Extraction of Rhodium(III) from Hydrochloric Acid Solution with Amide-Containing Tertiary Amine Compounds

Extraction of Rh(III) from a HCl solution with N,N-disubstituted amide–containing tertiary amine (ACTA) compounds (N,N-di-n-hexyl(N-methyl-N-n-octyl-ethylamide)amine (MonoAA), N-n-hexyl-bis(N-methyl-N-n-octyl-ethylamide)amine (BisAA), and tris(N-methyl-N-n-octyl-ethylamide)amine (TrisAA)) was investigated. The ACTAs extract Rh(III) more efficiently than tri-n-octylamine (TOA), and the extraction efficiency increases with increasing number of amide groups: TrisAA > BisAA > MonoAA ? TOA. For all ACTAs, the predominant Rh(III) complex extracted from 2 M HCl is probably {[RhCl₅(H₂O)]·(ACTA·H)₂}. The apparent basicity of the ACTAs and TOA varies in the opposite order from that observed for the Rh(III) extraction efficiency. Rh(III) can be readily back-extracted using 10 M HCl solution possessing a high selectivity over similarly loaded Pd(II) and Pt(IV).     

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.     

Chelating resins for mercury extraction based on grafting of polyacrylamide chains onto styrene–divinylbenzene copolymers by gamma irradiation

Chelating resins for mercury adsorption were prepared by grafting polyacrylamide chains onto styrene–divinylbenzene (Sty–DVB) copolymers by applying gamma radiation. Sty–DVB copolymers were synthesized by aqueous suspension polymerization employing different synthesis conditions. The copolymers were characterized by apparent density, surface area, pore size distribution and swelling capacity. The copolymers were irradiated using a ⁶⁰Co-γ source at room temperature in the presence of acrylamide solution in methanol. The grafting reaction was evaluated with the aid of elemental analysis, FTIR and thermogravimetric analysis (TGA). Hg(II) uptake measurements were carried out in batch experiments. The results showed that these resins can be successfully used for Hg(II) adsorption at ppm levels. The porosity degree of the copolymers influences the grafting yield as well as the Hg(II) complexation capacity of the chelating resins.     

STRIPPING RATE OF PROPIONIC ACID FROM STYRENE-DIVINYLBENZENE COPOLYMERIC MICROCAPSULES WITH TRI-W-OCTYL AMINE AS CORE MATERIAL

ABSTRACT

The stripping rate of propionic acid from microcapsules containing tri-n-octyl amine was investigated using distilled water and aqueous NaOH as stripping solutions. The experiments were conducted at 303K. The stripping rate was found to be controlled by diffusion through porous microcapsule membrane and increased with an increase in the concentration of propionic acid in the microcapsules for each solution system. It was found that the stripping rates in aqueous NaOH solution system was higher than in distilled water at the same concentration of propionic acid in microcapsules. The experimental results in the NaOH solution system could be analyzed using a permeation model considering mass transfer accompanied by irreversible instantaneous neutralization reaction between NaOH and the propionic acid/tri-n-octyl amine complex in the microcapsule membrane.     

Modeling and Optimization of Reactive Extraction of Gallic Acid Using RSM

Reactive extraction was experimentally investigated for recovery of gallic acid (GA) from the aqueous solution using tri-n-octylamine (TOA) as extractant in hexanol. All experiments were carried out according to statistical design in order to develop a regression model used to optimize the extraction of GA. Two independent variables were selected as: initial concentration of GA (C_GA0) in aqueous phase and concentration of TOA (C_TOA) in organic phase. The statistical analysis showed that both the independent variables had significant effect on response value, followed by the quadratic and interactive effect on response. A five-level central composite rotatable design (CCRD) was employed. Analysis of variance (ANOVA) showed a high coefficient of determination (R²?=?99.0%). The optimal extraction conditions of GA were determined as: C_GA0?=?2.01?g/L, C_TOA?=?6.8% v/v. At the optimum conditions, the experimental yield of GA was 91.9%, which was in close agreement with the predicted value of 93.2%.     

Preparation of trioctylamine-impregnated polystyrene–divinylbenzene porous resins for the collection of precious metals from water

A water-insoluble extracting solvent, trioctylamine (TOA), was solubilized in the aqueous micellar solution of a polyoxyethylene-type nonionic surfactant, polyethyleneglycol (10)-mono-4-nonylphenyl ether (PONPE-10). By mixing the solution and a polystyrene–divinylbenzene porous resin (Amberlite XAD-4), TOA was successfully impregnated into the resin. Gold(III), platinum(II), and palladium(II) were well extracted from hydrochloric acid to the TOA-impregnated resins. The extents of the extraction of platinum(II) and palladium(II) increased with increasing the amount of TOA impregnated. The TOA-impregnated filter disk was also prepared by passing aqueous mixture of PONPE-10 and TOA through an Empore disk involving polystyrene–divinylbenzene. The disk was useful for concentrating precious metals in water prior to their graphite furnace atomic absorption spectrometric analysis.     

EXTRACTION MECHANISM OF PALLADIUM WITH DIDODECYLMONOTHIOPHOSPHORIC ACID IN HEPTANE DILUENT

ABSTRACT

Kinetic study of the extraction of palladium(D) with didodecylmonothiophosphoric acid in n-heptane diluent was carried out using a stirred transfer cell to clarify the extraction mechanism. The effect of surfactants on the kinetics of palladium extraction was also investigated, to elucidate the role of surfactants used in liquid surfactant membranes. Moreover, the interfacial tension between the organic and aqueous phases was measured to elucidate the adsorption equilibrium of the surfactants. It was found that the interfacial activity of each surfactant is higher than that of the extractant. In the kinetic study of palladium extraction, the experimental results of the extraction rate was analyzed by the interfacial reaction model, taking into account of the adsorption of the surfactant and extractant. The rate-determining step of palladium extraction was the complex formation between four chloro-palladium complexes and the extractant at the interface, and the extraction rate constants of each palladium species were obtained. The extraction rate of palladium in n-heptane diluent was much faster than that in toluene. Additionally, it was suggested that there was particular interaction between the surfactant and extractant at the interface. The effect of the surfactant on the extraction rate was explained by taking into account the adsorption of the surfactant at the interface.     

Extraction and Separation Studies of Tin(IV) with Tri-n-octylamine

Abstract

A selective method is developed for the separation of tin(IV) from copper, manganese, zinc, cadmium, mercury, nickel, lead, aluminum, bismuth, and molybdenum with tri-n-octylamine either from hydrochloric or acetic acid media. The metal ion from the organic phase is stripped with nitric acid solution and determined photometrically in the aqueous phase. The method is shown to be applicable to synthetic mixtures.