Qiangbin Zhang

Synergistic Extraction of Lanthanides(III) with N‐p‐Methoxybenzoyl‐N‐Phenylhydroxylamine and Neutral Nitrogen Donors

Abstract We investigated the extraction equilibrium behavior of a series of trivalent lanthanide ions, (M3+), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions using a chloroform solution containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA or HL) combined with an adductant, 1,10‐phenanthroline (phen) or 2,2′‐bipyridyl (bipy). The synergistic species extracted were found to be {ML2(phen)(HL)}+(1/2)Tar2− and {ML2(bipy)(HL)2}+(1/2)Tar2−, where Tar2− is the tartrate ion. The stoichiometry, the extraction constants, and the separation factors of these systems were determined. We discuss the extractability and the separation factors in comparison with self‐adduct chelates, ML3(HL)2,(o), which were formed in the absence of phen or bipy.

Solvent Extraction of Lanthanides(III) with N‐p‐Phenylbenzoyl‐N‐phenylhydroxylamine

Abstract N‐p‐Phenylbenzoyl‐N‐phenylhydroxylamine (phenyl‐BPHA) was newly synthesized. The acid‐dissociation constant and distribution constant between chloroform and 0.1 mol dm−3 potassium chloride solution of phenyl‐BPHA were spectrophotometrically determined. The solvent extraction of lanthanides(III) (Ln) with phenyl‐BPHA was investigated. The representative lanthanides (Yb, Ho, Eu, Pr, and La) were all found to extract with compounds as self‐adducts of the form, LnL3(HL)2, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constant and separation factor were compared with those of the other derivatives of N‐benzoyl‐N phenylhydroxylamine (BPHA) previously reported. As the results, it was found that the separation factors for lanthanides(III) pairs represented by Pr/Eu, Eu/Yb, and Pr/Yb, with phenyl‐BPHA have moderate values by the comparison of those of other hydroxamic acids and other extractants.

Steric effect of substituents on the extraction of lanthanoids(III) with N-p-(n-, iso- and tert-)butylbenzoyl-N-phenylhydroxylamine.

N-p-(n-, iso- and tert-)Butylbenzoyl-N-phenylhydroxylamine (HL) was synthesized to evaluate the steric effect of the substituent on the mutual extraction separation of representative lanthanoids(III) (Ln). Lanthanoids(III) were all found to be extracted with compounds as self-adducts of the form LnL(3)(HL)(2). It was found that the structure of the substituents in N-p-butylbenzoyl-substituted N-phenylhydroxylamine is closely related to the separation factor for the pair of Yb/Eu. The separation factors for a pair of Eu/Yb with these compounds decreased in the order of tert-butyl derivative>iso->n-, with a decreasing Tafts E(s) value, that is, with an increasing steric effect of the substituent group. The correlation between the separation factor and the stereochemical shape of the substituent was also investigated.

DISTRIBUTION EQUILIBRIUM OF LANTHANIDE(III) COMPLEXES WITH N-BENZOYL-N-PHENYLHYDROXYLAMINE IN SEVERAL INERT SOLVENT SYSTEMS

ABSTRACT The distribution equilibrium of lanthanides(III) (Ln) with N-benzoyl-N-phenylhydroxylamine (BPHA, HL) in several inert solvent systems was studied. The representative lanthanides(III) (Yb, Eu and Pr) were all found to extract as self-adduct chelates of the form, LnL3(HL)m, (m = 1–3), containing a different number of neutral adduct molecules in extracted species. The differences in the number of neutral adduct molecules in extracted species with each solvents are attributed to the difference in the solvation trend for BPHA. The extraction constant and separation factor were determined in several inert solvent systems. It was found that the distribution ratio of lanthanide(III) tends to decrease with increases in the distribution constant of BPHA. Relationship between the polarity of the solvent and the extractability are also discussed.

Synergistic Extraction of Lanthanides(III) by Mixtures of N‐p‐Methoxybenzoyl‐N‐phenylhydroxylamine and 1,10‐Phenanthroline

Abstract We conducted a study on the equilibrium extraction behavior of the trivalent lanthanide ions (M3+), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions into chloroform solutions containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA, HL) and 1,10‐phenanthroline (phen). The synergistic species extracted was found to be {ML2(phen) (HL)}+(1/2)Tar2−, where Tar2− is tartrate ion. The extraction constants were calculated. The extraction separation behavior and extractability of lanthanides are discussed in comparison with the self‐adducted chelate, ML3(HL)2, which was extracted in the absence of phen, and synergistic extraction by mixtures of other extractants such as 2‐thenoyltrifluoroacetone, and neutral donors.

Spectrophotometic Determination Of Tin In Steels With2-(5-Nltro-2-Pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl)Amino]phenol

ABSTRACT A highly sensitive azo dye, 2-(5-nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (Nitro-PAPS), is used as a colorimetric reagent for the determination of tin(IV) content. Nitro-PAPS reacts with tin(IV) to form a water-soluble complex in 1.0 M acetic acid. Full color development is attained within 5 minutes, and maintains constant absorbance for at least 24 hours. The apparent molar absorptivity is 7.7 x 104 dm3 mol−1 cm−1 at a maximum wavelength of 580 ran. Beers law is obeyed for tin(IV) in the range of 0-1.2 μg ml−1. The proposed method is successfully applied to the determination of trace amounts of tin in steels.

Solvent Extraction of Lanthanides(III) with N‐Cinnamoyl‐N‐phenylhydroxylamine and Its Trifluoromethyl Derivative

Abstract N‐m‐Trifluoromethylcinnamoyl‐N‐phenylhydroxylamine (CF3‐CPHA) was synthesized. The acid‐dissociation constant and distribution constant between chloroform and water of CF3‐CPHA and N‐cinnamoyl‐N‐phenylhydroxylamine (CPHA), which was the mother compound of CF3‐CPHA, were determined spectrophotometrically. The extraction behavior of tervalent lanthanides (Ln), Pr, Eu, and Yb into chloroform solution containing CPHA or CF3‐CPHA was studied. They are extracted as self‐adduct chelates, LnL3(HL)3, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constants and separation factors for the lanthanides with CPHA and CF3‐CPHA were evaluated. The extraction constant with CPHA are smaller than that obtained with CF3‐CPHA. However, it is observed that CPHA possesses higher selectivity than CF3‐CPHA.

Pre-ashing of biological samples : a sample preparation technique for solid sampling ZAAS

SummaryA pre-ashing method by a conventional electrothermal furnace was used as a concentration technique for powdered biological samples in the solid sampling technique with GF-ZAAS. A relationship equation between the concentration factors and the concentrations of main inorganic components in biological samples has been established, and it has become possible to calculate the concentration factors, if the total concentration of K, Na, Mg and Ca, or total concentration of K and Mg, or the concentration of K only are known. The proposed method has been successfully applied to the direct determination of Co, Ni, Mn and Pb at the μg/kg levels in biological samples.