Sunil B. Zanje

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.

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.

A sensing behavior synergistic liquid–liquid extraction and spectrophotometric determination of nickel(II) by using 1-(2ˊ,4ˊ-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of foundry and electroless nickel plating waste water

ABSTRACT We report the sensing behavior of liquid–liquid extraction of nickel(II), which has been selectively determined from contaminated water samples by a simple UV-visible spectrophotometer. The method is based on synergistic extraction of nickel(II) by 1-(2ˊ,4ˊ-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2ˊ,4ˊ-dinitro APTPT] with pyridine. Nickel(II) reacts with 2ˊ,4ˊ-dinitro APTPT and forms a green-colored complex at pH 9.2. In addition, the Ni(II) ions were detected with the naked eye with the ligand. The absorbance of the coloured complex was measured at 660 nm and the colored complex is stable for more than 48 h even in the presence of other competing ions. The system obeyed Beer’s law in the concentration range of 5–50 μg mL−1 of nickel(II) and the optimum range evaluated by Ringbom’s plot method is 10–40 μg mL−1 with an excellent linearity and a correlation coefficient of 0.999. The molar absorptivity and Sandell’s sensitivity of the extractive species were found to be 1.64 × 103 dm3 mol−1 cm−1 and 0.0585 μg cm−2 in the presence of pyridine, and 7.4 × 102 dm3 mol−1 cm−1 and 0.78 μg cm−2 in the absence of pyridine, respectively. The composition of nickel(II)-2ˊ,4ˊ-dinitro APTPT-pyridine was established by the slope ratio method, the mole ratio method and Job’s method of continuous variation. It was found that the metal:ligand:synergent (M:L:Sy) ratio is 1:2:2. To assess the precision and accuracy of the developed method, determinations were carried out at n = 5. The relative standard deviation of all measurements does not exceed 0.16%. Excellent selectivity was found towards the Ni(II) ion due to a specific complex formation between the Ni(II) ion and the organic ligand. In the extraction of Ni(II), several affecting factors, including the solution pH, ligand concentration, equilibrium time, initial Ni(II) ion concentration and foreign ions, were investigated and the applicability of the method was checked by the analysis of synthetic mixtures and alloys. The developed method was successfully used for the determination of nickel(II) from waste water effluents from the foundry region and the nickel plating industry (Kolhapur city). The results obtained by the developed method were also confirmed by AAS. We claimed from this study that Ni(II) could be successfully determined by the spectrophotometric method developed in the current work. The present work is obviously much simpler than the conventional method comprising multistep processes.

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.