Julio César Aguilar

Extraction of Cu(II), Fe(III), Ga(III), Ni(II), In(III), Co(II), Zn(II) and Pb(II) with LIX® 984 dissolved in n-heptane

Abstract The solvent extraction of some metal ions with LIX ® 984 dissolved in n -heptane was studied. The extraction order observed as the pH of the aqueous solution increases is Cu(II) > Fe(III) > Ga(III) > Ni(II) > Co(II) > Zn(II) ≈ Pb(II). The experimental data obtained are explained considering hydroxyoxime association and metal complex solvation. Numerical analysis of the data with the LETAGROP-DISTR program suggested the presence of the CuR 2 , CuR 2 2HR, FeR 3 , GaR 3 , NiR 2 , InR 3 , CoR 2 HR, ZnR 2 3HR and PbR 2 HR species in the organic phase. Complex formation between the metal cations and the buffers used was considered in the calculations. The values of the equilibrium constants for the extraction reactions are reported.

Solvent extraction of Ga(III), Cd(II), Fe(III), Zn(II), Cu(II), and Pb(II) with ADOGEN 364 dissolved in kerosene from 1–4 mol dm−3 HCl media

Abstract Distribution equilibria of approximately 0.01 mol dm −3 Ga(III), Cd(II), Fe(III), Zn(II), 0.1 mmol dm −3 Cu(II) and Pb(II) from 1–4 mol dm −3 HCl media were studied using the commercial trialkylamine ADOGEN 364 (ADG) dissolved in kerosene as extractant. Self-association of this extractant in the organic phase was taken into account when analyzing the extraction reactions. Numerical analysis of the data with the LETAGROP-DISTR program allowed the evaluation of the equilibrium constants of the proposed equilibria. The dependence of the extraction constant values with ionic strength was analyzed using the specific interaction theory (SIT) treatment, from which the interaction coefficients of Ga(III), Cd(II), Fe(III), Zn(II), Cu(II), and Pb(II) with chloride anion were estimated. Data previously obtained for HCl and In(III) extraction were also analyzed in this form. Results obtained on the stoichiometry of extracted complexes are consistent with similar published work.

Adsorption of Metallic Cations on Silica Gel-Immobilized 8-Hydroxyquinoline

TLC-grade silica gel was functionalized with 8-hydroxyquinoline via a catalyzed Mannich amminomethylation reaction. The resulting solid was characterized by FT-IR and used as a sorbent for 0.05–5 mmol·L−1 Cu(II), Cd(II), Zn(II), Pb(II), and Fe(III) from aqueous solutions in the batch mode. Experiments were carried out in both single and multiple cation solutions. The influence of the aqueous media composition on the adsorption process, the possible adsorbed species, and the adsorption kinetics are discussed. Overall equilibrium constants for these processes are reported.

An SLM system for the extraction of In(III) from concentrated HCl media using ADOGEN 364 as carrier

The coupled transport of In(III) from concentrated HCl media (2.2-4 mol/dm 3 ) on a supported liquid membrane system using as carrier the commercial trialkylamine ADOGEN 364 dissolved in kerosene was studied. The effect of different parameters such as the stirring rates of feed and strip solutions, carrier concentration, solution volume/membrane area ratio and initial metal concentration on the system are discussed. The experimental results obtained are explained on the basis of a physicochemical model considering diffusion of the metal species in the feed solution, chemical reaction in the membrane surface and diffusion of species through the membrane phase. The values of the mass transfer coefficients in the aqueous and organic phases and the rate constants of the reactions were determined. The influence of the hydrochloric acid concentration on these parameters is established.

Complexation of ω-thiocaprolactam with heavy metals: terminal and bridging coordination modes in cadmium and silver compounds

The soft base w-thiocaprolactam (1-azacycloheptane-2-thione, Hthcl) reacts with Cd II and Ag I nitrate salts, giving two new coordination complexes, [Cd(NO 3 ) 2 (C 6 H 11 NS) 4 ] and [Ag 4 (C 6 H 11 NS) 8 ](NO 3 ) 4 . The first compound, tetrakis(1-azacycloheptane-2-thione-S)bis(nitrate-O)cadmium(II), presents a slightly distorted octahedral coordination geometry, with two η 1 -NO 3 fragments in a cis arrangement and four Hthcl molecules bonded via the S atom of the thiocarbonyl group; coordination bond lengths involving S atoms range from 2.5768 (19) to 2.6828 (18) A. The cationic moiety of the silver compound, tetrakis[μ-(1-azacycloheptane-2-thione-S)]tetrakis[(1-azacycloheptane-2-thione-S)silver(I)] tetranitrate, is a centrosymmetric tetranuclear cluster containing eight Hthcl molecules, four of which are in terminal positions [coordination distances 2.4850(19) and 2.478 (2) A], as in the Cd complex, while the other four bridge two metallic ions each, with coordination distances in the range 2.4608 (17)-2.6976(18) A.

Determination of germanium(IV) in sulphide ores by differential pulse polarography in pyrogallol-sulfuric acid media☆

Abstract The evaluation of the polarographic response (dpp) of Ge(IV) in several sulfuric acid media containing pyrogallol allowed to establish optimum conditions for the reduction of this ion. In the media studied, the reduction of Ge(IV) provides a signal that can be used for quantitative analysis. This research led to a method for the determination of Ge(IV) in sulphide ores that involves sepatation of interferences by a liquid-liquid extraction technique. Using a static mercury drop electrode the method yielded a calculated detection limit of 3 × 10−8 M.