Permeation of AuCl4− Across a Liquid Membrane Impregnated with A324H+Cl− Ionic Liquid

In the system Au(III)-HCl-A324H+Cl−, liquid-liquid extraction experiments were used to define the extraction equilibrium and the corresponding extraction constant; furthermore, the facilitated transport of this precious metal from HCl solutions across a flat-sheet supported liquid membrane was investigated using the same ionic liquid as a carrier, and as a function of different variables: hydrodynamic conditions, concentration of gold(III) (0.01–0.1 g/L), and HCl (0.5–6 M) in the feed phase, and carrier concentration (0.023–0.92 M) in the membrane. An uphill transport equation was derived considering aqueous feed boundary layer diffusion and membrane diffusion as controlling steps. The aqueous diffusional resistance (Δf) and the membrane diffusional resistance (Δm) were estimated from the proposed equation with values of 241 s/cm and 9730 s/cm, respectively. The performance of the present carrier was compared against results yielded by other ionic liquids, and the influence that other metals had on gold(III) transport from both binary or quaternary solutions was also investigated. Gold was finally recovered from receiving solutions as zero valent gold nanoparticles.

Permeation of AuCl4- across a Liquid Membrane Impregnated with A324H+Cl- Ionic Liquid

On the system Au(III)-HCl-A324H+Cl-, liquid-liquid extraction experiments were used to define the extraction equilibrium and the corresponding extraction constant, and the facilitated transport of this precious metal, from HCl solutions, across a flat-sheet supported liquid membrane was investigated, using the ionic liquid as carrier, as a function of hydrodynamic conditions, concentration of gold(III) (0.01-0.1 g/L), and HCl (0.5-6 M) in the feed phase, and carrier concentration (0.023-0.92 M) in the membrane. An uphill transport equation was derived considering aqueous feed boundary layer diffusion and membrane diffusion as controlling steps. The aqueous diffusional resistance (Δf) and the membrane diffusional resistance (Δm) were estimated from the proposed equation, being their values 241 s/cm an 9730 s/cm, respectively. The performance of the present carrier was compared against results yielded by other ionic liquids, and also it was investigated the influence that other metals had on gold(III) transport both from binary or quaternary solutions. Gold was finally recovered from receiving solutions as zero valent gold nanoparticles.

Transport of Indole 3-acetic Acid through Bulk Liquid Membrane Influence of Carrier in the Diffusion Process

The paper presents a study of the phenomena that take place at membrane system interfaces in the process of indole-3-acetic acid (IAA) transport. The results were obtained in a bulk liquid membrane system using trioctylamine, tributylphosphate, trioctilphosphine oxide as carriers in chloroform. The main equilibriums that take place at the interface feed phase% membrane phase were identified and the diffusion coefficient of the indole-3-acetic acid complex (DLS) and the extraction constant (Kex) were assessed. The influence of the chemical potential gradient on these parameters was considered.

A RESEARCH ON KINETIC MODELLING ON EXTRACTION OF TOTAL POLYPHENOL FROM OLD TEA LEAVES

In this study, kinetic modeling by investigating the effect of material sizes, water/material ratios and temperatures was conducted. Polyphenol concentration increased with reducing size, increasing the water/material ratio and temperature. The results showed that under extraction conditions such as the material size of 0.3 mm, the water/sample ratio of 15/1, the extracting temperature of 60 oC, and extracting time of 40 minutes, the polyphenol content obtained was of 77.33 mgGAE.g-1 with value of initial extraction rate reached 50.90 mgGAE.g-1.min-1 and the activation energy was determined as 16.162 kJ/mol. Polyphenol extraction dynamic model from the old tea leaves relied on the assumption of the quadratic function has been successfully constructed to predict the extraction process and mechanism. Based on the kinetic equation, extraction parameters, including Ce extraction ability, extraction velocity, extraction constant k, and activation energy E can be determined, facilitated optimization, designed, simulated and controlled significant industrial projects.

The development of methods for the determination of residues of the herbicide halauxifen-methyl in barley and rape

Optimal conditions for the extraction of halauxifen-methyl from grain, straw and green mass of barley; seeds, oil and green mass of rape, as well as the conditions for the purification of extracts were selected on the basis of the distribution constants (P) and distribution coefficients (D) experimentally determined at a temperature of (20 ± 1) °C. At the first stage, acetonitrile, or acidified acetonitrile, or a mixture of water and acetonitrile were used to extract the pesticide. Halauxi fen-methyl was found to be a weakly hydrophobic substance and it exhibits the properties of a weak base in aqueous solutions. For the purification of plant material extracts hexane – 1 mol/L aqueous solution of hydrochloric acid and hexane – 10 % K2HPO4 aqueous solution were successfully used (to neutralize the acid and increase the extraction constant due to the salting out effect). The samples obtained after purification are sufficiently pure. So, the residual amounts of halauxifen-methyl can be determined by widespread liquid chromatography with diode array (ultraviolet) detection at the level, which is equal or lower to the maximum allowable content of herbicide in barley and rape.

An extraction-chromogenic system for vanadium(IV,V) based on 2,3-dihydroxynaphtahlene

A liquid-liquid extraction-chromogenic system for vanadium(IV, V) containing 2,3-dihydroxynaphtahlene (DN), 2,3,5-triphenyl-2H-tetrazolium chloride (TTC), water and chloroform was studied in detail. When the vanadium is in the oxidation state of IV, the extracted species are aggregates containing three 1:2:1 (V:DN:TTC) ion-pair units composed of triphenyltetrazolium cations (TT+) and chelate anions {[VIVO(DN)(DNH)]− (I) and/or [VIV(OH)(DN)2]− (II)}. When the initial oxidation state of vanadium is V and the DN concentration is high, vanadium(V) is reduced by DN to a lower oxidation state, V(IV). However, at low DN concentration, vanadium(V) can enter the organic phase as a part of an ion-pair consisting of TT+ and [VVO2(DN)]− (III). The ground-state equilibrium geometries of the anions I, II, and III were optimized by quantum chemical calculations using BLYP/6-31++G⋆. The following characteristics were determined under the optimum conditions for VIV extraction: absorption maximum λmax = 333 nm, molar absorptivity ε333= 2.1x104 dm3 mol−1 cm−1, Sandell’s sensitivity SS = 2.4 ng cm−2, and fraction extracted E = 98%. The conditional extraction constant was calculated by two independent methods. The calibration graph was linear in the range 0.1-3.1 μg cm−3 (R2=0.9994) and the limit of detection was 0.03 μg cm−3.

Solvent extraction of trivalent actinides with di(2-ethylhexyl) phosphoric acid

We carried out solvent extraction on the trivalent actinides of Am, Cm, Cf, and Fm and the lanthanides (except Pm) using di(2-ethylhexyl)phosphoric acid (HDEHP) in benzene by a batch method. The extraction constants of the HDEHP complexes for these elements were determined systematically under identical conditions. The tetrad effect was clearly observed in the variation of the extraction constants of the lanthanide series. We found that the extraction constant for Fm(III) is much smaller than that for Dy(III), which have similar ionic radii. The extraction constants for Am(III), Cm(III), and Cf(III) are similar to those for corresponding Ln(III) having similar ionic radii. Two possibilities that account for the lower extraction constant of Fm(III) is suggested.

SYNERGISTIC EXTRACTION OF COBALT(II) WITH MIXTURE OF ACYL-PYRAZOLON AND CROWN-ETHER IN STRONSIUM(II) ENVIRONMENT

Synergistic extraction of cobalt(II) with mixture of acyl-pyrazolon (HL) and crown-ether (E) in the Sr(NO3)2 environment has been studied. In this research, HPMBP (phenyl-1-methyl-3-benzoil-4-pyrazolon-5) was used, with three different kinds of crown-ether, i.e. (benzo-15-crown-5), DB18C6 (dibenzo-18-crown-6) and DB24C8 (dibenzo-24-crown-8), in chloroform. In the bulk environment of stronsium, a cobalt coextraction and stronsium occured with species ESrNO3+,Co(PMBP)3-, and E = B15C5, while Co(PMBP)2E and ESr,Co(PMBP3)2, with E = DB18C6. There was no coextraction when using crown-ether DB24C8, with the extracted species Co(PMBP)2E. Values of extraction constant presented in log Kex were -6.08 (B15C5), - 4.51, -12.55 (DB18C6), and - 4.57 (DB24C8), respectively. Keywords: synergistic, cobalt (II), strontium (II), coextraction.

Study of the Gold Extraction Using Tetra N-Butyl Ammonium Chloride-Chloroform

The existence of the AuCl4- ion in the solution as the function of pH before performing the extraction of gold in the system of tetra N-butylammonium chloride (TBACI) -chloroform has been studied. The experimental data showed that AuCl4- ion was hydrolyzed at pH 5-10 and, an amorf dark-brown precipitate was appeared at pH 11-14. Amount of gold in the solution at pH 14 before extraction was around 70%. Study of the extraction has been carried out by investigating the influence of pH and TBACI concentration on the extraction efficiency. The experimental result indicated that TBACI was very efficient extractant for the extraction of gold from aqueous halide with the efficiency higher than 99%. The extraction of Gold in the TBACI-chloroform was effective at pH 0-4 with minimum concentration of TBACI 10-3 M, and the calculated Kex (extraction constant) was 5.07x10-4.