Vishal J. Suryavanshi

2-Octylaminopyridine assisted solvent extraction system for selective separation of palladium(II) ion-pair complex from synthetic mixtures and real samples

Herein, 2-octylaminopyridine (2-OAP) amine is used in the liquid–liquid extraction of palladium(II) from aqueous salicylate media. It is found that pH does not affect the metal extraction process in the pH range of 1.8–2.4. Palladium(II) complex formation was verified by a log–log plot, whereas from the slope analysis, the ion pair complex stoichiometry 1:1 (metal:ligand) and 1:3 (metal:acid) was confirmed. The extraction system was optimized for the choice of diluent (xylene) as well as for the effective stripping agent (5.0 M ammonia). The selectivity for palladium(II) was found to be maintained when the organic phase (0.03 M 2-OAP in xylene) is used to extract the palladium(II). The extraction saturation capacity of palladium(II) was determined from 0.02 M sodium salicylate solution with 10 mL 0.03 M 2-OAP, and its experimental value exceeds 2.5 mg under the experimental conditions. Stripping of palladium(II) from the loaded organic phase was performed with 5.0 M ammonia. The extraction with varying parameters like equilibrium time, temperature, diluents, concentration of extractant, loading capacity, regeneration power and stability of extraction was also studied. The extraction behavior of associated metals, namely, noble metals and base metals, has been investigated, and the conditions for binary separation involving these metal ions have been optimized. Based on the extraction protocol, palladium(II) has been recovered from real samples.

Liquid–liquid extraction and separation of lead(II) by using N-n-octylcyclohexylamine as an extractant: analysis of real samples

A method for the determination of micro amounts of lead(II) is described. N-n-Octylcyclohexylamine (N-n-OCA) was employed as an ion-pair forming a neutral [N-n-OCAH+PbCl3−] complex in hydrochloric acid medium. The quantitative extraction of lead(II) was observed with N-n-OCA (0.03 to 0.055 M) in a dichloromethane (DCM) and xylene mixture (1 : 4), from hydrochloric acid medium (3.0 to 5.0 M). The extracted ion-pair complex was back stripped with 0.5 M nitric acid and determined spectrophotometrically with PAR. The quantitative extraction of lead(II) was found in the DCM : xylene ratio of 1 : 4 as a mixed solvent system. The various parameters studied, such as concentration of acid, N-n-OCA concentration, equilibrium time, solvent study, back stripping agents and loading capacity were optimized for the quantitative extraction of lead(II). The stoichiometry of the extracted ion-pair complex was determined on the basis of the slope analysis method, and it was found to be 1 : 3 : 1 (metal : chloride : extractant). The proposed method was successfully applied to the analysis of diverse ions, binary mixtures of associated metal ions, ternary mixtures, alloys, ayurvedic samples and water samples, by using N-n-OCA and lead(II) was determined using PAR and the results of analysis were confirmed by ICP-OES.

Liquid–liquid extraction of thorium(IV) with N-n-heptylaniline from acid media

The extraction behavior of thorium(IV) from sulphuric acid medium with N-n-heptylaniline in xylene. Various parameters like reagent concentration, acid concentration, equilibration time, diverse ions and effect of diluents were studied. Thorium(IV) was selectively extracted and separated from many metal ions. The nature of the extracted species was determined. Thorium(IV) was analyzed from monazite ore and gas mantle.

Development of a reliable analytical method for the precise extractive spectrophotometric determination of osmium(VIII) with 2-nitrobenzaldehydethiocarbohydrazone: Analysis of alloys and real sample

The proposed method demonstrates that the osmium(VIII) forms complex with 2-NBATCH from 0.8molL(-1) HCl at room temperature. The complex formed was extracted in 10mL of chloroform with a 5min equilibration time. The absorbance of the red colored complex was measured at 440nm against the reagent blank. The Beers law was obeyed in the range of 5-25μgmL(-1), the optimum concentration range was 10-20μgmL(-1) of osmium(VIII) as evaluated by Ringboms plot. Molar absorptivity and Sandells sensitivity of osmium(VIII)-2NBATCH complex in chloroform is 8.94×10(3)Lmol(-1)cm(-1) and 0.021μgcm(-2), respectively. The composition of osmium(VIII)-2NBATCH complex was 1:2 investigated from Jobs method of continuous variation, Mole ratio method and slope ratio method. The interference of diverse ions was studied and masking agents were used wherever necessary. The present method was successfully applied for determination of osmium(VIII) from binary, ternary and synthetic mixtures corresponding to alloys and real samples. The validity of the method was confirmed by finding the relative standard deviation for five determinations which was 0.29%.

Extraction of iridium(III) by ion-pair formation with 2-octylaminopyridine in weak organic acid media

ABSTRACT To extract iridium(III), various physicochemical parameters were studied. 2-Octylaminopyridine was used for the extraction of iridium(III) from acetate medium at 8.5 pH. Quantitative extraction of iridium(III) was achieved via ion-pair formation of cation [2-OAPH+] and anion [Ir(CH3COO)4]−. The stripping of iridium(III)-laden organic phase was carried out 2 M HCl (3 × 10 mL) . The stoichiometry of the extracted ion–pair complex was found to be 1:4:1 (metal: acetate: extractant). The extracted species [2-OAPH+. Ir(CH3COO)4−] is assumed to be an ion association product of [Ir(CH3COO)4] − and [2-OAPH]+. The proposed method was successfully used in the separation of iridium(III) from binary and ternary mixtures. Analysis of various alloy samples was also carried out.

2-Nitrobenzaldehyde Thiocarbohydrazone Assisted Precise Extraction Spectrophotometric Method for the Determination of Ruthenium(III) in Alloy and Catalysts

A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)‒2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1‒6 g/mL of ruthenium(III), the optimum concentration range was 2‒5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 104 L/mol/cm and 0.0075 μg/cm2, respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.

Development of liquid-liquid extraction and separation method for ruthenium(III) with 2-octylaminopyridine from succinate media: Analysis of catalysts

Ruthenium(III) has been efficiently extracted from 0.05 M sodium succinate at pH 9.5 by 2-octylaminopyridine in xylene and stripped with aqueous 10% (w/v) thiourea solution and determined spectrophotometrically. Various parameters viz., pH, weak acid concentration, reagent concentration, stripping agents, contact time, loading capacity, aq.: org. volume ratio, solvent has been thoroughly investigated for quantitative extraction of ruthenium(III). The utility of method was analyzed by separating the ruthenium(III) from binary mixture along with the base metals like Cu(II), Ag(I), Fe(II), Co(II), Bi(III), Zn(II), Ni(II), Se(IV), Te(IV), Al(III) and Hg(II) as well as platinum group metals (PGMs). Ruthenium(III) was also separated from ternary mixtures like Os(VIII), Pd(II); Pd(II), Pt(IV); Pd(II), Au(III); Pd(II), Cu(II); Fe(II), Cu(II); Ni(II), Cu(II); Co(II), Ni(II); Se(IV), Te(IV); Rh(III), Pd(II); Fe(III), Os(VIII). The stoichiometry 1: 2: 1 (metal: succinate: extractant) of the proposed complex was determined by slope analysis method by plotting graph of logD[Ru(III)] versus logC[2-OAP] and logD[Ru(III)] versus logC[succinate]. The interference of various cations and anions has been studied in detail and the statistical evaluations of the experimental results are reported. The method was successfully applied for the analysis of ruthenium in various catalysts, synthetic mixtures corresponding to the composition of alloys and minerals.

Development of a rapid and reliable liquid-liquid extractive method for the effective removal of chromium(VI) from electroplating waste water and tannery effluents

A rapid and selective liquid-liquid extractive system is developed for extraction of Cr(VI) by employing N-n-OCA reagent and xylene as solvent. Quantitative extraction of Cr(VI) is observed in the concentration range of 0.4 to 0.7 M HCl. The extracted [Cr(VI)-N-n-OCA] complex from the organic phase was back extracted by 6.0 M ammonia (3 × 10 mL) and spectrophotometrically quantified. Various parameters were explored to study their influence on quantitative extraction of Cr(VI) by varying N-n-OCA concentration, equilibration time, effect of diluents, acid concentration and diverse ions. Stoichiometry of the extracted complex showed 1: 1 ratio of acid and amine. The relative standard deviation of the developed method is 0.09 with respect to calibration range 0.2 to 0.8 μg mL–1. The validity of the proposed method was checked by applying it to the associated and toxic metals in binary, synthetic mixtures and ternary effluents.

Solvent extraction studies of rhodium(III) by using n-octylaniline from malonate media: Analysis of synthetic mixtures and alloys

Abstract Herein, we have developed the solvent extraction method for the selective separation of precious rhodium(III). Various physicochemical parameters like pH, malonate concentration, n-octylaniline concentration, equilibrium time, aq: org phase ratio, and loading capacity of n-octylaniline are optimized for the quantitative recovery of the rhodium(III). The composition of the extracted species was determined by plotting the log–log graph of Log D[Rh(III)] vs. Log C[n-octylaniline] and Log D[Rh(III)] vs. Log C[malonate]; the stoichiometry was found to be (metal: acid: extractant) 1:2:1. The proposed method was successfully applied for the separation of rhodium(III) from various binary and ternary mixtures of associated metal ions. The separation of the rhodium(III) from real samples was also carried out with the proposed method. The proposed method was applied for analysis of synthetic mixture corresponding to alloys such as pseudo-palladium, iron–rhodium alloy, platinum–rhodium alloy, and rhodium–platinum catalyst.