Separation of molybdenum (VI) by extraction withn-octylaniline from hydrochloric acid medium

n-Octylaniline in bezene was used for the extractive separation of molybdenum (VI) from hydrochloric acid medium. Molybdenum(VI) was extracted quantitatively from 10 ml aqueous solution 1.5M in hydrochloric acid and 10M in lithium chloride into 10 ml of 10%n-octylaninline in benzene. It was stripped from the organic phase with 5% aqueous ammonia solution and estimated spectrophotometrically with thiocyanate at 465 nm. The interference of various ions has been studied in detail and conditions have been established for the determination of molybdenum(VI) in synthetic mixtures and alloy samples.     

The sorption of molybdenum from solutions of nitric acid

The sorption of molybdenum(VI) on KU-2 × 8 and AV-17 × 8 ionites from 6 n solutions of nitric acid was studied. The sorption of molybdenum(VI) on the cationite and anionite changed depending on solution composition and nitric acid concentration. The sorption and electromigration data were used to determine the isoelectric point of molybdenum in solutions of nitric acid.     

Thermal decomposition of the solvent extracted molybdenum (VI) complexes from hydrochloric acid solutions with trioctylamine and trioctylmethylammonium chloride

The complexes of molybdenum(VI) with trioctylamine (TOA, R₃N) and trioctyl methylammonium chloride (TOMAC, R₃R'NCl) were prepared by drying in vacuo the organic solutions for the extraction of molybdenum(VI) from hydrochloric acid solutions at low and higher acidities, respectively, by TOA and TOMAC in benzene. The resulting complexes were examined by thermal analysis (TG and DTA) in air and under the atmosphere of nitrogen, and their thermally decomposed products such as volatile matters and residues by gas chlomatography, X-ray diffraction study and infrared spectrophotometry. It was found that their complexes decompose thermally to MoO₃ by cracking of alkyl groups combined with molybdenum(VI) ion. Accordingly the thermal decomposition process of those complexes is discussed and the probable structure of the complexes is proposed on the basis of the results obtained.

---

Zusammenfassung Komplexe von Molybdän(VI) mit Trioktylamin (TOA, R₃N) und Trioktylmethylammoniumchlorid (TOMAC, R₃R'NCl) wurden hergestellt, mittels TG und DTA in Luft und in Stickstoffatmosphäre untersucht. Die thermischen Zersetzungsprodukte der Komplexe (flüchtige Substanzen und Rückstände) wurden mittels Gaschromatographie, Röntgendiffraktion und IR-Spektroskopie untersucht. Es wurde gezeigt, daß die Komplexe thermisch zu MoO₃ zerfallen, indem die an das Molybdän(VI)-Ion gebundenen Alkylgruppen abgekrackt werden. Die Ergebnisse der thermischen Zersetzungsprozesse wird diskutiert und auf der Basis der erhaltenen Ergebnisse die wahrscheinliche Struktur der Komplexe dargelegt.

---

---

Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday

---

The author wishes to thank Dr. H. Watanabe and Mr. T. Takahashi for assistance with experimental work, and also the Koei Chemical Co., Ltd. for samples of TOA and TOMAC.     

Separation of molybdenum(VI) from other elements by solvent extraction with dibenzo-18-crown-6 from hydrochloric acid medium

DB-18-C6 was used for the extractive separation analysis of molybdenum(VI) from a range of other elements. Molybdenum(VI) was quantitatively extracted from 8M hydrochloric acid with 0.01M DB-18-C6 in nitrobenzene. It was stripped from the organic phase with 2M nitric acid and determined spectrophotometrically with Tiron at 390 nm. Molybdenum was separated from a large number of elements in binary mixtures, the tolerance limit for most elements being very high. Selective extraction of molybdenum permits its separation from barium, thorium, cesium, rubidium, strontium, lanthanum, chromium(III) and cerium(III). The method was extended for the analysis of molybdenum in a soil sample.     

二-(2-乙基己基)磷酸在不同稀释剂中对钼(VI)的萃取

考察了Mo(VI)在盐酸水相与-二(2-乙基己基)磷酸的不同稀释有机相间的分配平衡,观察到萃取平稀常数按正辛烷、四氯化碳、苯、氯信、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂性进行了关联,得到萃取平衡常数与稀释剂的极性参数E~T间良好的线性关系.此外,本文还提出了H~2MoO~4的酸、碱式解离常数分别为0.158和1.21×10^13.     

Sorptive separation of molybdenum(VI) from rhenium-containing solutions

It is shown that Purolite S957 cation-exchange resin containing phosphonic-acid and sulfonic groups is capable of selectively sorbing molybdenum(VI) in the presence of rhenium(VII) in solution.     

Sorption of molybdenum(VI) from mineral salt solutions

Changes in the ionic forms of molybdenum and conditions of sorption on the anionite AV-17 × 8 from mineral salt solutions at concentrations of 0.05–2 N and pH of medium 1–6 were revealed.     

One-electron oxidation of organic substrates by oxochloride complex of rhenium(VI) in hydrochloric acid solutions

Photoreduction reactions of Re(VII) in the presence of an electron donor — diphenylamine (DPA) and hydroquinone (HQ) in concentrated hydrochloric acid solutions — were studied using the pulse photolysis method. The short-lived complex of rhenium(VI) ReOCL₅ undergoes one-electron oxidation reactions with both DPA to form a cation-radical DPA^+. and with HQ to form a semiquinone radical. The decay of the cation-radicals DPA^+. proceeds by a second order reaction with the formation of a stable product (_max=590 nm)Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 3, pp. 365–368, May–June, 1987.     

Column chromatographic separation of molybdenum (VI) from alloys with poly-(dibenzo-18-crown-6) from a hydrochloric acid medium

A very simple column chromatographic separation method has been developed for molybdenum (VI) using poly-(dibenzo-18-crown-6). The separations are carried out from hydrochloric acid medium. The adsorption of molybdenum (VI) on a poly-(DB-18-C-6) was quantitative from 2.5 to 10.0M HCl. Amongst the various eluents tested, 0.5M ammonium hydroxide was found to be an efficient eluent. Molybdenum (VI) was separated from a large number of elements in binary form, as well as from multicomponent mixtures. The method was applied for the analysis of molybdenum from various alloy samples. The method is very simple, rapid, selective and reproducible. The reproducibility of the procedure is +/-2%.     

Solvation of thiocyanate complexes of tungsten(VI) by 5-(4-pyridyl) nonane from aqueous hydrochloric acid solutions

5-(4-Pyridyl)nonane has been evaluated as a solvent for trace amounts (<5·10^–5 M) of tungsten(VI) from aqueous chloride-thiocyanate solutions. Remarkable enhancements in metal extractability are observed on the addition of SCN^– to aqueous hydrochloric acid solutions. Extremal partition coefficients are obtained from 0.1 M HCl in 0.2 M KSCN. Diminutions of the metal extractability are produced by relatively high (>0.5 M) SCN^– concentrations and increased concentration of the supporting acid. Slope analysis data, under optimal parameters, indicates the most probable composition of the extractable species as WO₂(SCN)₂·2P_YN. Neutral anions do not have any significant effect on the D values. Behaviour of a number of metal ions has been checked using optimal aqueous conditions of extraction. The investigation shows that the reagent has a great potential for the preconcentration of a number of metal ions including the common toxins.     

The extraction of vanadium(IV) from hydrochloric acid solutions by di-(2-ethylhexyl)-phosphoric acid

The distribution of vanadium(IV) between hydrochloric acid solutions and solutions of di-(2-ethylhexyl)-phosphoric acid (DEHPA; HX) in organic solvent has been investigated under different conditions. Both the aqueous and organic phases have been examined spectrophotometrically. IR and electron spin resonance spectroscopies have been applied to the organic extracts. The mechanism of extraction is discussed on the basis of the results obtained.     

Electrodialytic recovery of chromium(VI) from hydrochloric acid solutions with liquid membranes based on tri-n-octylamine

A study of the process of electrodialytic recovery of chromium(VI) from a solution of 0.01 M K₂Cr₂O₇ in 0.1 M HCl with liquid membranes containing tri-n-octylamine with addition of di(2-ethyl hexyl)phosphoric acid in1,2-dichloroetrhane to dilute solutions of various acids determined the optimal process conditions: electrodialysis current density and the composition of the starting and receiving aqueous solutions and liquid membranes. It was found that all the liquid membranes studied provide a complete recovery of chromium(VI) anions from the starting solution.     

Extraction of iridium(IV) by dihexyl sulfoxide from hydrochloric acid solutions

The extraction of iridium(IV) by dihexyl sulfoxide from hydrochloric acid solutions was studied. Optimum conditions for the extraction of iridium(IV) were determined. It was found that an ion-association mechanism of iridium(IV) extraction took place in the test extraction systems at a phase contact time of 10 min. As the phase contact time was increased, the extraction took place by a mixed mechanism. One extractant molecule was incorporated into the inner coordination sphere of the iridium(IV) ion. This decreased the charge of the extracted complex to unity.     

The extraction of molybdenum(VI) from perchloric acid solution by tri-n-butyl phosphate

The extraction of molybdenum(VI) by tri-n-butyl phosphate (TBP) from 1 M NaClO₄ medium has been investigated as a function of molybdenum concen     

Extraction of phosphorus(V), molybdenum(VI), and tungsten(VI) from fluoride solutions

The influence of titanim(IV) and silicon(IV) on the extraction of phosphorus(V), molybdenum (VI), and tungsten(VI) fluoride complexes by tributyl phosphate was studied.

     

Extraction of molybdenum(VI) by 4-(5-nonyl)pyridine in benzene from aqueous mineral acid solutions containing thiocyanate ions

Extraction of Mo(VI) by 4-(5-nonyl)pyridine (NPy) in benzene from mineral acid solutions containing thiocyanate ions has been investigated at room temperature (23±2°C). From mineral acid (HCl, HNO₃, and H₂SO₄) solutions alone Mo(VI) is not extracted quantitatively while the presence of small amounts of KSCN in the system augments the extraction by a large factor. Stoichiometric studies indicate that ion-pair type complexes (NPyH)₂·[MoO₂(SCN)₄] are responsible for the extraction. Separation factors determined at fixed extraction conditions (0.1M Npy/C₆H₆–0.1M acid +0.2M KSCN) reveal that Ag(I), Cu(II), Co(II), Zn(II), Hg(II) and U(VI) are co-extracted while a clean separation from alkali metals, alkaline earths and some transition metals like Ln(III), Zr(IV), Hf(IV), Cr(III), Cr(VI) and Ir(III) is possible. Some of the complexing anions like oxalate, citrate, acetate, thiosulfate or ascorbate do not affect the degree of extraction of Mo(VI) allowing it to be recovered from diverse matrices.     

Extraction of chlororuthenium(III) complexes by triazole derivatives from hydrochloric acid solutions

The extraction of ruthenium(III) by triazole derivatives from hydrochloric acid solutions has been studied. The extraction of ruthenium(III) is implemented by the ion-association mechanism. The composition of the extraction compound has been determined using electronic, ¹H NMR, ¹³C NMR, and IR spectroscopy and elemental analysis.