Acid Concentration In Aqueous Phase Research Articles

Selective separation of zirconium(IV) from uranium(VI) using dioxoamide ligand present in ammonium based ionic liquid: An application towards spent metallic fuel reprocessing

The alloy of an actinide (U or Pu) with zirconium (6%) has been proposed as metallic fuel. The removal of zirconium from the dissolver solution is required prior to the separation of actinides during reprocessing. In this context, the extraction behavior of zirconium was studied in a solution of 2-ethylhexyl- and the decyl-derivative of benzodioxodiamide, abbreviated as BD and BDD, respectively, in ionic liquid medium. Instead of the conventional imidazolium ionic liquid that displayed several drawbacks, strongly hydrophobic ionic liquids such as methyltributylammonium bis(trifluoromethylsulfonyl)imide ([N1444][NTf2]) and methyltrioctylammonium bis(trifluoro-methylsulfonyl)imide ([N1888][NTf2]) have been employed, as a diluent, in conjunction with the BD and BDD ligands for the extraction of Zr(IV). The effect of nitric acid concentration in aqueous phase, duration of equilibration, interference of uranium and the effect of temperature on the extraction of Zr(IV) in BD present in ionic liquid was studied. The number of BD-ligands involved in the extraction of zirconium was determined. The results showed the possibility of removing zirconium from the bulk quantity of uranium present in the dissolver solution.

Reactive extraction of succinic acid using supercritical carbon dioxide

ABSTRACTReactive 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.

Studies on the adsorption behavior of americium and europium on radiolytically degraded solvent impregnated resin containing neutral and acidic extractants

The trivalent actinide selective neutral extractants such as carbamoylmethylphosphine oxide (CMPO) and bis-(2-ethylhexyl)diglycolamide (TEHDGA) in conjunction with an acidic extractant bis-2-ethylhexylphosphoric acid (HDEHP) have been impregnated in Tulsion ADS 400, and the resultant solvent impregnated resin (SIR) has been evaluated for the radiolytic stability towards gamma radiation. The extraction behavior of Am(III) and the loading behavior of Eu(III) in the SIR was studied as a function of absorbed dose up to 550 kGy, at different nitric acid concentrations in aqueous phase. The extraction isotherm of Eu(III) in various SIRs have been fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption models. The extraction results and modeling of extraction isotherms obtained at various absorbed dose levels have been reported in this paper.

Kinetics of Extraction of Tributyl phosphate (TBP) from Aqueous Feed in Single Stage Air-sparged Mixing Unit

Abstract The mass transfer studies involving kinetics of extraction of Tributyl phosphate (TBP) saturated in 0.3 M nitric acid using different organic extractants viz. normal paraffinic hydrocarbon (NPH), kerosene, dodecane etc. have been performed in a novel air-sparged single stage mixing unit. Based on the mechanism, a simple kinetic model (analogous to first order) is proposed and experimental data was analyzed. The optimization studies including the effect of diluent, % TBP in NPH, Organic to Aqueous phase (O/A), air flowrate and the nitric acid concentration in aqueous phase have been performed. The experimental and modeled kinetic results suggest that the optimized conditions for the extraction of TBP (174 ppm to 65.5 ppm) from aqueous 0.3 M HNO3 feed are found to be, 3 % TBP in NPH as extracting solvent, O/A is 1/1 and volumetric air flowrate is 15 LPM. However, if pure NPH used as an extractant with these operating conditions 100 % removal can be obtained.

Rhenium(VII) solvent extraction with mixtures of tertiary amine and oxygen-containing extractants from sulphate media

The extraction of rhenium(VII) from sulfate media by mixtures of tri-iso-octylamine (TIOA) and oxygen-containing reagents (2-octanol, 2-octanone, phenetole) has been examined. The synergistic effect for mixtures of TIOA and electron-donor reagents (ketone, ether) was established. The maximal synergistic enhancement factor (3.1) was observed for the “TIOA-2-octanone” mixture. Rhenium(VII) was extracted by this mixture as (R3NH)ReO4∙0.2B. The maximal rhenium(VII) extraction was found at weak acid concentrations in aqueous phase (pH~2–3), whereas the “TIOA-ketone” mixture could extract rhenium(VII) from weak alkaline media (pH~7–9) in contrast to the “TIOA-alcohol” mixture.Effective stripping from the loaded “TIOA-2-octanone” mixture was achieved with a 3mol/L NH4OH in 2–3 stages.

Liquid–Liquid Extraction of Sulfuric Acid from Aqueous Sulfate Waste Solution using Alamine 336/Kerosene/TBP Solvent

Generally the metallurgical industries generate huge amounts of harmful environmental wastes, which may be solids, liquids, or gases in their nature. The present study aims to recovery sulfuric acid (227 g/l) from wastes generated during hydrometallurgical digestion of titanium ores with sulfuric acid for TiO2 production. For this purpose Alamine 336/kerosene solvent was used. Various extraction parameters as Alamine 336 concentration, shaking time, type of diluent, and O/A phase ratio were studied and optimized. Under the optimum conditions, Mc-Cabe Thiele diagram results indicated that, after four extraction stages the acid concentration in aqueous phase was reduced from the initial value of 227 g/l to about 17 g/l. Stripping of the loaded sulfuric acid from the organic phase was done with warm water (60°C). Stripping parameters as water temperature, stripping time, and A/O phase ratio were studied. Under the stripping the loaded acid concentration in organic phase was reduced from 210 to 6 g/l which matched theoretically by McCabe Thiele diagram.

Studies on extraction and permeation of cadmium(II) using Cyphos IL 104 as selective extractant and ion carrier

In this work the comparative studies between solvent extraction and transport across polymer inclusion membranes (PIMs) have been carried out for the removal of cadmium(II) from aqueous chloride solutions. Cyphos IL 104 (trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate) was used as extractant/ion carrier in both processes. Effect of different parameters such as hydrogen ion concentration, chloride ion concentration as well as hydrochloric acid concentration in aqueous phase on cadmium(II) extraction has been investigated. Cellulose triacetate membranes with Cyphos IL 104 as carrier have been prepared and applied for removal of Cd(II) from HCl and NaCl solutions. Cd(II) ions were effectively removed from the source phase by transport through PIM into 1M H2SO4 as the receiving phase. Also separation of Cd(II) was carried out from 1M HCl solution containing Cu(II), Co(II) and Ni(II) and the separation coefficients were found in order of SCd/Cu<SCd/Co<SCd/Ni. The data generated from the transport of Cd(II) study were compared with that of conventional solvent extraction investigation.

Optimization and validation of a HPLC method for simultaneous determination of aflatoxin B1, B2, G1, G2, ochratoxin A and zearalenone using an experimental design

A reversed-phase HPLC optimization strategy is presented for investigating the separation and retention behavior of aflatoxin B1, B2, G1, G2, ochratoxin A and zearalenone, simultaneously. A fractional factorial design (FFD) was used to screen the significance effect of seven independent variables on chromatographic responses. The independent variables used were: (X1) column oven temperature (20–40°C), (X2) flow rate (0.8–1.2 ml/min), (X3) acid concentration in aqueous phase (0–2%), (X4) organic solvent percentage at the beginning (40–50%), and (X5) at the end (50–60%) of the gradient mobile phase, as well as (X6) ratio of methanol/acetonitrile at the beginning (1–4) and (X7) at the end (0–1) of gradient mobile phase. Responses of chromatographic analysis were resolution of mycotoxin peaks and HPLC run time. A central composite design (CCD) using response surface methodology (RSM) was then carried out for optimization of the most significant factors by multiple regression models for response variables. The proposed optimal method using 40°C oven temperature, 1 ml/min flow rate, 0.1% acetic acid concentration in aqueous phase, 41% organic phase (beginning), 60% organic phase (end), 1.92 ratio of methanol to acetonitrile (beginning) and 0.2 ratio (end) for X1–X7, respectively, showed good prediction ability between the experimental data and predictive values throughout the studied parameter space. Finally, the optimized method was validated by measuring the linearity, sensitivity, accuracy and precision parameters, and has been applied successfully to the analysis of spiked cereal samples.

Modeling and optimization of tartaric acid reactive extraction from aqueous solutions: A comparison between response surface methodology and artificial neural network

In the last decades, response surface methodology (RSM) and artificial neural network (ANN) has become the most preferred methods for non-parametric modeling and optimization of separation processes in chemical engineering. This paper presents a comparative study between RSM and ANN for reactive extraction optimization. Reactive extraction of tartaric acid from aqueous solution using Amberlite LA-2 (amine) has been chosen as the case study. The extraction efficiency was modeled and optimized as a function of three input variables, i.e. tartaric acid concentration in aqueous phase C AT (g/L), pH of aqueous solution and amine concentration in organic phase C A/O (% v/v). Both methodologies have been compared for their modeling and optimization abilities. According to analysis of variance (ANOVA) the coefficient of multiple determination of 0.841 was obtained for RSM and 0.974 for ANN. The optimal conditions offered by RSM and genetic algorithm (GA) have led to an experimental extraction efficiency of 83.06%. On the other hand, the ANN model coupled with GA has conducted to an experimental reactive extraction efficiency of 96.08% for the following optimal conditions of * C AT = 5.58 g/L; * pH 1.84 and * C A/O = 6.99 (% v/v). The value of 96.08% is the maximal value of extraction efficiency obtained throughout this work. Thus, ANN-GA has demonstrated the ability to overcome the limitation of quadratic polynomial model in solving optimization problem for this case study. Both models have been employed for construction of response/output surface plots in order to reveal the influence of input variables on extraction efficiency as well as to figure out the interaction effects between variables.

A comparison between TEHA and Cyanex 923 on the separation and the recovery of sulfuric acid from aqueous solutions

In this study, the separation of sulfuric acid with TEHA and Cyanex 923 from acidic solutions by solvent extraction method was investigated. Extraction of sulfuric acid with TEHA and Cyanex 923 is an exothermic reaction and the enthalpy changes of the reaction were found to be − 6.34 and − 2.24 kJ, respectively. Comprehensive study on determining the stoichiometric coefficients of sulfuric acid in the extraction equation, using slope analysis method, lead to a new approach for this procedure. This study showed that when organic phase extracts more than 100 g/L sulfuric acid, the number of extracted sulfuric acid molecules by TEHA, n, is estimated to be 1. While, each mole of TEHA extracts 2 mol of sulfuric acid when organic phase extracts less than 100 g/L sulfuric acid. In addition, the value of n, using Cyanex 923 as extractant, is estimated to be 1. Using McCabe–Thiele diagram results showed that after 4 stages, sulfuric acid concentration in aqueous phase was reduced from the initial value of 200 to the values of 30 and 5 g/L when octanol concentration in organic phase was 20 and 40%vol, respectively. While, using Cyanex 923 as extractant, 5 stages were needed to reduce the sulfuric acid concentration from 100 to 5 g/L.

Extraction and separation of neptunium(IV), plutonium(IV) and americium(III) by bidentate organophosphorus Extractant

This paper summarized the extraction and separation of Np(IV), Pu(IV) and Am(III) with dihexyl-N,N-diethyl carbamyl methylene phosphonate (DH-DECMP)-diethyl benzene (DEB) in nitric acid medium. The distribution ration of Np(IV), Pu(IV) and Am(III) was studied as a function of a number of parameters such as concentration of nitric acid, salting-out reagents in the aqueous phase, contact time, and temperature. Stripping and separation of Np(IV), Pu(IV) and Am(III) from pregnant organic phase were studied. The suitable stripping and separation conditions were obtained. The enthalpy changes ΔH Np, ΔH Pu, ΔH Am associated with their extraction process were estimated individually. The composition of extracted complex of Np(IV), Pu(IV) and Am(III) was determined. Effect of Contact Time and Temperature. The experiment shows that equilibrium for all extracted species is reached in approximately 30 seconds of contact. The distribution ratios of Np(IV), Pu(IV) and Am(III) decrease with increase of temperature, while the effect of temperature on distribution ratio (D) of nitric acid is negligible. Consequently, the extraction process of the metallic ions is considered as an exothermic and it is not desired to increase temperature during extraction. In the plot of logD vs. 1/T(K) the straight lines were obtained. According to the slope of line and Van't Hoff equation: Δ lg D/Δ(1/T) = −ΔH/2.303 R, the enthalpy changes ΔH associated with extraction process were estimated as follows: ΔH Np ⋍−3.7 Kcal/Mol ΔH Pu ⋍−7.9 Kcal/Mol ΔH Am ⋍−7.6 Kcal/Mol Effect of Concentration of Nitric Acid. The effect of nitric acid concentration in aqueous phase on extraction of trivalent and tetravalent actinides was investigated. The distribution ratios of Pu(IV), Np(IV) and Am(IV) increase with concentration of nitric acid, so it is capable of extracting these actinides in higher concentration of HNO 3. The data on the distribution ratios of these elements in 3 M HNO 3 medium are as follows: D Np(IV) = 221 D Pu(IV) = 101 D Am(III) = 2.2 Effect of Concentration of the Extractant. The distribution ratios(D) of these elements increase with DHDECMP concentration. The logarithmic plots of D Np, D Pu and D Am versus DHDECMP concentration are straight lines with slopes of 2.0, 1.9 and 2.9 respectively. Therefore, the extraction reaction for Np(IV), Pu(IV) and Am(III) with DHDECMP can be expressed as: Np 4+ aq + 4NO − 3 aq + 2DHDECMP org ⇌ Np(NO 3) 4·2DHDECMP org Pu 4+ aq + 4NO − 3 aq + 2DHDECMP org ⇌ Pu(NO 3) 4·2DHDECMP org Am 3+ aq + 3NO − 3 aq + 3DHDECMP org ⇌ Am(NO 3) 3·3DHDECMP org Effect of Concentration of Salting-Out Reagent. The experiment shows that the distribution ratios(D) of trivalent and tetravalent actinides increase obviously with concentration of Al(NO 3) 3 and NaNO 3 in aqueous phase. When the concentration of Al(NO 3) 3 is equal to 1.5 M in M HNO 3 aqueous phase, the distribution ratios for Np(IV) and Am(III) are 1.15 × 10 3 and 10 respectively. Back-Extraction. The stripping condition of Np, Pu and Am from the organic phase were investigated. It is shown that the Am(III) can recovered quantitatively after twice stripping with 0.01 M HNO 3. With (0.05–0.2 M) HNO 3–0.05 M H 2C 2O 4 for Pu(IV), Np(IV) to be stripped or with (0.05–0.2 M) HNO 3–0.05 M Fe(NH 2SO 3) 2 for Pu(IV) to be stripped, the back-extraction percentage is more than 97 after twice contacts. Separation of Americium from Neptunium or Plutonium by Back-Extraction. Experiments show that the Am(III) was quantitatively stripped from the organic phase with 0.05–0.2 M HNO 3, while most of the Np(IV) and Pu(IV) is remained in the organic phase (Table I). From Table I it can be seen that the separation factor of Am and Np or Am and Pu is more than 50. Consequently, this method may be applied to separating Am from Pu(IV) and Np(IV). t001 Stripping Data for Am, Np and Pu. a Stripping Solution 0.05 M HNO 3 0.2 M HNO 3 Back-Extraction Am 74 71 Percentage Pu 1.0 1.3 Np 1.2 1.2 Separation Factor Am/Pu 74 54 Am/Np 61 59 a Organic Phase: 30 Vol% DHDECMP-DEB pre-equilibrated with 3 M HNO 3 solution containing 239Np, 239Pu and 241Am tracer.: 30 °C ± 1 °C. Contact time: 5 min.

Calculation of Distribution Ratios of Rare Earth Elements in Multistage Counter Current Extraction with HDEHP

Extraction of rare earth elements with di (2-ethylhexyl) phosphoric acid (HDEHP) - tributyl-phosphate (TBP)-n-paraffin system was studied as functions of concentrations of the quantity of H+ released into aqueous phase. The ratio of rare earth elements extracted into organic phase was found to depend on the initial composition of the aqueous solution. The ratios determined for various concentrations of rare earth elements and acid were shown as a linear function of the concentrations of acid in aqueous phase and that of rare earth elements in organic phase after extraction. The acid concentration in aqueous phase after extraction can be estimated from any initial concentrations of acid and rare earth elements in aqueous solution by this equation. Also a graphic process of experimental results could give approximate values of distribution ratio for various initial concentrations of rare earth elements and nitric acid. For calculation of the distribution ratio of each stage in multi-stage counter current extraction, a computation code was programmed on the basis of the graphical process. The calculated values agreed well with those obtained experimentally in multistage extraction.

Calculation of Distribution Ratios of Rare Earth Elements in Multistage Counter Current Extraction with HDEHP

Extraction of rare earth elements with di (2-ethylhexyl) phosphoric acid (HDEHP) - tributyl-phosphate (TBP)-n-paraffin system was studied as functions of concentrations of the quantity of H+ released into aqueous phase. The ratio of rare earth elements extracted into organic phase was found to depend on the initial composition of the aqueous solution. The ratios determined for various concentrations of rare earth elements and acid were shown as a linear function of the concentrations of acid in aqueous phase and that of rare earth elements in organic phase after extraction. The acid concentration in aqueous phase after extraction can be estimated from any initial concentrations of acid and rare earth elements in aqueous solution by this equation. Also a graphic process of experimental results could give approximate values of distribution ratio for various initial concentrations of rare earth elements and nitric acid. For calculation of the distribution ratio of each stage in multi-stage counter current ex...