Complex formation and liquid-liquid extraction of the cobalt(II) by 2-hydroxythiophenol and its derivatives in the presence of hydrophobic amines system Текст научной статьи по специальности «Химические науки»

ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)

541.49:543.4:542.28:546:82

COMPLEX FORMATION AND LIQUID-LIQUID EXTRACTION OF THE COBALT(II) BY 2-HYDROXYTHIOPHENOL AND ITS DERIVATIVES IN THE PRESENCE OF

HYDROPHOBIC AMINES SYSTEM

A.Z.Zalov1, N.A.Verdizade\ G.V.Babayeva1, Sh.A.Ibrahimova2

Azerbaijan State Pedagogical University 2Baku State University [email protected] Received 25.10.2017

Mixed-ligand complexes of cobalt(II) with hydroxythiophenols (OP) {2-hydroxythiophenol (HTP) and its derivatives (2-hydroxy-5-aminthiophenol (HATP), 4-hydroxy-3-thiolsulfonic acid (HTSA), 4-hydroxy-3-thiolbenzoic acid (HTBA), 4-Nitro-2-hydroxythiophenol (HNTP)} in the presence of hydro-phobic amines (Am) have been studied by spectrophotometric methods. Extraction of mixed ligand complexes is maximal at pH 3.6-6.3. The optimum conditions for the formation and extraction of mixed-ligand compounds have been found and the ratios of components the complexes have been determined. The Beer's law was applicable in the range of 0.05-3.2 ^g/ml. The effect of foreign ions and reagents on the extraction was studied. The new method is free from common interferences. A procedure has been developed for extraction - spectrophotometry determination of cobalt in different objects.

Keywords: cobalt, solvent, spectrophotometry, ion-associate, hydrophobic amines, hydroxythiophenol.

doi.org/10.32737/0005-2531-2019-4-39-47

Introduction

Cobalt is a transition element of high industrial importance because of its valuable alloying, dyeing, magnetic, catalytic and plating properties. It is also of biological significance due to its ability to be an active center of coenzymes, e.g. vitamin B12 [1]. A great variety of photometric reagents is known for the determination of cobalt. However, the studies aiming to find and investigate new photometric reagents with different functional groups are still going on. For photometric determination of cobalt there are quite selective reagents o-nitrozofenole group or a similar structure with the oxime group [2].

Oxyphenolate, oxythiophenolate and di-thiophenolate complexes of cobalt are insoluble in chloroform, while mixed-ligand complexes with hydrophobic amines and aminophenols easily dissolve in various organic solvents [3-9]. In this respect, a very promising reagent is oxythio-phenol (OP), which contains one hydroxyl and one sulphohydryl groups and is a sulfur-containing analogue of mononuclear polyphenols with one oxygen atoms replaced with sulfur atoms. The present work is devoted to studying the reaction of a complex formation of Co(II) with oxythiophenol (OP) in the presence of hydro-phobic amines (Am). Oxythiophenols 2-hydroxy-thiophenol (HTP) and its derivatives (2-hydr-

oxy-5-aminthiophenol (HATP), 4-hydroxy-3-thiolsulfonic acid (HTSA), 4-hydroxy-3-thiol-benzoic acid (HTBA), 4-Nitro-2-hydroxythio-phenol (HNTP) were used in the presence of hy-drophobic amines (Am). As hydrophobic amine 2(N, N-dimethyl aminomethyl)-phenol (APi) and 2(N,N-dimethylaminomethyl)-4-methylphe-nol (AP2) were used.

Experimental part

Reagents and apparatus. A stock solution (1p,g/ml) of cobalt(II) was prepared by dissolving in water an exact linkage CoSO4 7H2O in water containing 2 ml concentrated H2SO4, and diluted by water to 1 liter [10]. The concentration of the cobalt solution was adjusted grav-imetrically [11]. Solutions of OP and Am in chloroform (0.01M) were used. OP were synthesized according to the procedure [12]. Their purity was verified by melting point determination and paper chromatography. The synthesized compound was identified by NMR and IR spectroscopy (Table 1). To create the optimal acidity, 0.1M solutions of KOH and HCl or ammonium acetate buffers were applied. The extractant was purified chloroform.

The absorbance of the extracts was measured using a SF 26 spectrophotometer and KFK-2 photocolorimeter. Glass cells with optical path

Table 1. The research results of IR and NMR spectroscopy

Reagent IR (KBr) 'H NMR (300,18 MT^ CsD6)

HTP 3470 cm-1 v(OH), 3050 cm-1 v(CH), 2580 cm-1 v(SH), 1580 cm-1 (C6H5). 5 5.48 (s, 1H - OH), 5 3.57 (s, 1H, - SH ), 5 7.8 (s, 2H Ar-H), 5 6.95 (s, 1H, Ar-H), 5 7.05 (s, 1H, Ar-H).

HATP 3460 cm-1 v(OH), 3050 cm-1 v(CH), 2570 cm-1 v(SH), 1418 and 1130 cm-1 v(-NH2), 1555 cm-1 v (CH). 5 5.24 (s, 1H- OH), 5 3.32(s, 1H, - SH), 5 7.11 (s, 2H, Ar-H), 5 2.38 (s, 2H, -NH2), 5 7.05 (s, 1H, Ar-H).

HTSA 3465 cm-1 v(OH), 3050 cm-1 v(CH), 2572 cm-1 v(SH), 1210 and 1130 cm-1 v(SO3H), 1565 cm-1 v(C6H5). 5 5.39 (s, 1H,- OH), 5 3.42(s, 1H, 1SH), 5 7.21 (s, 2H, Ar-H), 5 2.59 (s, H, - SO3H ), 5 7.15 (s, 1H, Ar-H).

HTBA 3458 cm-1 v(OH), 2568cm-1 v(SH), 3040 cm-1 v(CH), 1420 and 1300 cm-1 v(COOH), 1535 cm-1 v(CsH5). 5 5.15 (s, 1H,- OH), 5 3.28 (s, 1H, -SH), 5 7.05 (s, 2H, Ar-H), 5 1.42 (s, 1H, COOH ), 5 7.26 (s, 1H, - Ar-H).

HNTP 3462 cm-1 v(OH), 2564 cm-1 v(SH), 3045 cm-1 v(CH), 1700 cm-1 v(NO2), 1535 cm-1 v^gHs). 5 5.16 (s, 1H,- OH), 5 3.25(s, 1H, - SH), 5 7.18 (s, 2H, Ar-H), 5 7.41 (s, 1H, - Ar-H).

of 5 or 10 mm were used. pH of aqueous phase was measured using an I-120.2 potentiometer with a glass electrode. Muffle furnace was used for dissolution of the samples.

General procedure

General procedure for the Determination of Cobalt(II). Portions of stock solutions of cobalt(II) varying from 0.1 to 1.0 ml with a 0.1-ml step, a 2.2 ml portion of a 0.01 M solution of OP, and a 2.5 ml portion of a 0.01M solution of Am were placed into calibrated test tubes with ground-glass stoppers (the volume of the organic phase was 5 ml). The required value of pH was adjusted by adding 1M HCl. The volume of the aqueous phase was increased to 20 ml by using distilled water. In 15 minnute after the complete separation of the phases, the organic phase was separated from the aqueous phase and the absorbance of the extracts was measured on KFK-2 at room temperature and 540 nm (£=0.5 cm).

Determination of cobalt(II) in steel [Steel M 441(0.012%Co) and HM^.5/M 627x (0.055% Co)]. A weighed sample of 0.2 g was dissolved in 20 ml of H2SO4 (1:1) was oxidized with a few drops of concentrated nitric acid and evaporated twice lo vapor SO3. The precipitated salt was dissolved in 20 ml of 15% tartaric acid under heating, the solution was cooled, adjusted with water to 100 ml in a volumetric flask, stirred and filtered. An aliquot of 5 ml was put into a separatory funnel then , was added 1 ml of 10% hydroxylamine solution, 1

ml of 3% ascorbic acid were added andthere was determined cobalt used in the proposed procedures.

Determination of Co(II) in sewage water and bottom sediments. 1 l taken for analysis of waste water is evaporated to obtain a precipitate, it is not boiled. The precipitate was dissolved in 5 ml of HNO3, was transferred to a 50 ml flask and diluted to the mark with water.

Determination of Co(II) in plant. A portion of beans (10 g) was crushed and dried in a porcelain dish at 1200C. The dry residue is heated in a muffle furnace at 5000C. The ash was dissolved in diluted (1:1) HNO3 and evaporate to moist salts, which are then dissolved in water, filtered into a volumetric flask of 100 ml. The cobalt content is determined with OP and AP.

Results and discussion

Charge of the complexes. The charge of the Co(II)-OP binary complexes was determined by electromigration and ion-exchange. Experiments on electromigration in a U-shaped tube and on sorption on EDE-10P anion exchanger demonstrated the anionic nature of the complexes. Under the experimental conditions, these red binary complexes were insoluble in nonpolar organic solvents. However, when AP were introduced the formation of electroneutral chloroform extractable ternary complexes was observed.

Choice of organic solvent. For the extraction of complexes we used CHCl3, CCl4, C6H6, C6H5CH3, C6H4(CH3)2, C6H5O, C2H4Q2,

isobutanol and isopentanol. The extractivity of the complexes was estimated by the distribution coefficient and recovery. CHCl3, C6H5CI, C2H4CI2 appeared to be the best extractants. All the further investigations were carried out with chloroform. The concentration of cobalt in the organic phase was determined with 2-nitroso-1-naphtol [11] by photometric measurements after back extraction, while in the aqueous phase it was determined by the difference. The basicity of Am hardly influences the recovery of niobium. After a single extraction with chloroform, 96.9-99.2% of cobalt was extracted as an ion associate.

Effect of pH of the aqueous phase. The effect of pH on the formation of Co(II)-OP-AP complex was studied, in order to find a suitable pH that can be adopted in the determination of cobalt(II) (Figure 1). The absorbance was found to be maximum in the pH range 2.3-7.3. Hence further analytical investigations were carried out in media of pH 3.6-6.3 (Table 1). Extraction of Co(II) enhanced with the increase in the acidity of the initial solution; the further increase in acidity led to the gradual decrease of recovery, which was obviously associated with

a decrease in the concentration of the ionized form of OP. Probably, it is present in the solution in the non-dissociated state. At pH > 7.2, the complexes were hardly extracted, obviously because of the decrease in the degree of Am protonation.

Influence of reagent concentration and incubation time. For the formation and extraction of mixed-ligand complex (MLC), a 20-25-fold excess of complexing reagents is required; for example, the optimal conditions for formation and extraction of these compounds are provided by (1.10-2.25) xio-3 M OP and (0.921.24) 10-3 M AP. A large excess of hydropho-bic amine interferers with the determination. However it was found that the presence of excess of the reagent solution does not alter the absorbance of the color reaction. Unlike single-ligand complexes, mixed-ligand complexes of Co(II) with OP and AP were stable in aqueous and organic solvents and did not decompose for two days, or over a month after extraction. The required duration of the phase contact was 10 min (Figure 2).

0.6 0.5

I 0.4

•e

o

j§ 0.3 <

0.2 0.1

—

D—O-O-0 4

r n - 3 —0 2 2

1

T 1 1 1 1 1 1 1

2 3 4 5 6 7 8

pH

Fig. 1. Absorbance of Co-HITP-OP extracts function of the pH of the aqueous phase: 1 - Co-HATP-AP2, 2 - Co-HTP-AP2, 3 -Co-HTST-AP2, 4 - Co-HNTP-AP2; Cco(n) = 1.7 10-5mol/l, COP = 2.0 10-3mol/l-1, CAP = 2.5 10-3 mol/l-1; X=540 nm, KFK-2, /=0.5 cm.

J

0 600 1200 1800 2400 Shaking time, s

Fig. 2. Effect of shaking time on the absorbance: 1 - Co-HATP-AP2, 2 - Co-HTP-AP2, 3 - Co-HTST-AP2, 4 - Co-HNTP-AP2; CCo(n) = 1.7 10-5 mol/l, pH 4.0-6.0, X=540 nm, KFK-2, /=0.5 cm.

Electronic absorption spectra. Neither the metal ion nor the reagent has appreciable absorbance at specified wave lengths. Hence further studies were carried out at 540-565 nm (Figure 3). The reagent has minimum absorbance at the maximum absorbance of the complex. Hence further absorbance measurements were made at 540 nm.

Stoichiometry of the complexes and the mechanism of complexation. Starik-Barbanel relative yield method, equilibrium shift method, crossed lines method and Asmus' method were employed to elucidate the composition of the complex [13]. The results suggest the complex composition of 1:2:2 (Co:OP:AP). The formation of MLC can be presented in the following way. When cobaltion interact with two molecules of OP, they form doubly-charged anionic

complexes, which are extracted with two molecules of protonated AP. Formed ion-association complex between anionic chelates of cobalt(II) with OP and hydrophobic aromatic amines.

Calculation of extent of polymerization of complexes was carried out on the equation [9]. The made calculations showed that MLC in an organic phase won't be polymerized and are in a monomelic form (y=1.05-1.12). The values of the molar absorption coefficients (sk= (2.62-3.01)104 l mol-1 cm-1), biphase stability constants (lgP= 10.02-10.79), the extraction constants of the complexes (lg^ex = lgP + lgD = 12.50-13.68) and the distribution coefficient (lgD= [Co]org/ [Co]aq = 2.19-2.90), as well as the recovery of cobalt (R = D/100+ Vaq/Vorg = 97.5 - 99.5) are determined [13] (Table 1) [14].

e

I 0.4 bar o

M 0.3

3

0.2 0.1

Fig. 3. Absorption of mixed-ligand complexes: 1 - Co-HATP-AP2, 2 - Co-HTP-AP2, 3 - Co-HTST- AP2, 4 - Co-HNTP- AP2; CCo(n) = 1.7 10-5mol/ l, COP = (1.10-2.25)-10-3mol/ l, CAP = (0.92-1.24)- 103 mol/ l; X=540 nm, pH 4.0-6.0, KFK-2, 1=0.5 cm.

520 530 540 550 560 570 580 590 Wave length, nm

Table 1. Optical characteristics, precision and accuracy of the spectrophotometric determination of Co(II) with OP and AP

Compound The pH range of education and extraction The pH range of maximum extraction R,% lgD T, ^max, nm e-10-4 lgP lg^ex Working range / ^g 5 ml

Co-HATP-AP1 3.5-7.2 4.8-6.2 97.5 2.19 540 2.62 10.65 12.84 1.40-95

Co-HATP-AP2 3.6-7.3 4.9-6.3 97.7 2.23 542 2.68 10.79 13.02 1.38-95

Co-HTP-AP1 3.3-7.0 4.5-5.9 97.9 2.27 545 2.70 10.42 12.69 1.36-96

Co-HTP-AP2 3.5-7.2 4.7-6.0 98.0 2.29 548 2.76 10.57 12.86 1.35-98

Co-HTST-AP1 2.8-6.6 4.2-5.6 98.4 2.39 550 2.85 10.21 12.50 1.34-100

Co-HTST-AP2 3.0-7.0 4.5-5.9 98.5 2.42 555 2.84 10.35 12.79 1.34-97

Co-HTBT-AP1 2.5-6.4 3.8-5.3 98.8 2.52 558 2.90 10.07 12.59 1.32-100

Co-HTBT-AP2 2.8-6.7 4.0-5.5 98.9 2.55 560 2.93 10.22 12.77 1.30-100

Co-HNTP-AP1 2.3-6.1 3.6-4.9 99.3 2.75 562 2.96 10.93 13.68 1.25-100

Co-HNTP-AP2 2.5-6.2 3.8-5.0 99.5 2.90 565 3.01 10.02 12.92 1.25-100

i'ave number, cm"' Wave number.

Fig.4. IR spectra of HATP (a) and the Co(II)-HATP-APi (b).

The existence of clearly defined absorption bands at 2410-2415 cm1 in the IR spectrum of the complex indicates the coordination of the Am in the protonated form [15]. The disappearance of the band at 2580 cm-1, characteristic for the spectrum of HATP, and appearance of corresponding bands in the spectrum of the complex, which are shifted toward lower frequency, suggests that the sulphur atoms are involved in complex formation. The observed de-

crease in the intensity of the absorption bands at 3200-3600 cm-1 with a maximum at 3460 cm-1 and the appearance of a broad band in the region of 3050-3150 cm-1 shows that the hydrox-yl group participates in the formation of a coordination bond (Figure 4).

Proceeding from the obtained data, we propose the following structure for the extracted ternary complex:

(H3Q2

OH

h2n

O

XC0 /

s/ N

•nh2

OH

+

n-№)2

Influence of interfering ions. The influence of elements, often accompanying cobalt in various objects, as well as the influence of masking substances, is considered. The influence of the It has been found that the determination of cobalt with OP and AP is not adversely affected by alkali and alkaline-earth metals, W(VI), Mo(VI), Mn(II), Pb(II), V(V), Cr(III) etc. In the optimal conditions, the complex-formation strongly interferes with Fe(III), Cu(II), Zn(II), Ni(II). To eliminate the effect of zinc, cobalt can be determined in phosphate buffer media, with zinc completely masked. To eliminate the influence of iron and nickel, the possibility of acidification after complex formation under optimal conditions has been studied, since cobalt with OP and AP forms kineti-cally inert complexes. It turned out that acidification up to a pH of 0.8 does not affect the optical density of the solution. In acidic media, iron and nickel complexes are unstable, and as a result the selectivity of the reaction during acidification significantly recourses. Complexes of copper in acid media are stable, therefore, to

O

eliminate its influence, the possibilities of using masking agents have been studied. It turned out that the definition of cobalt with OP and AP2 does not contain up to 250 mg of oxalate, tartrate, citrate and fluoride ions, thiourea, ascorbic acid, 0.8 g of pyrophosphate, up to 0.2 g of hydrogen peroxide, up to 0.05 g of EDTA and hydroxylamine unitol interfere. The presence of thiourea greatly increased the selectivity factor in the presence of copper. The results are shown in Table 2.

Effect of Co(II) Concentration. The adherence to Beer's law was studied by measuring the absorbance value of the series of solutions containing different concentrations of the metal ion. A linear calibration graph drawn between absorbance and the metal ion concentration indicates that Co(II) may be determined in the range 0.05-4.0 ^g/ml (Table 1). The pertaining calibration graph is shown in the Figure 5. Table 3 shows the data allowing to compare the analytical characteristics of the methods for determining cobalt with some methods already known [16-27].

S

Analytical applications. The proposed method under the already established optimum conditions was applied for the determination of

Co(II) in various objects. The results presented in Table 4 indicate the successful applicability of the proposed method to real sample analysis.

Table 2. Effect of concomitant ions on the results of the photometric determination of cobalt(II) (40 ^g/25 ml of cobalt)

Concomitant ions Admissible weight excess of concomitant ions by weight

HATP +AP2 HTP +ap2 HTST +ap2 HTBT +ap2 HNTP +AP2

Mg 1900 1950 1930 1800 1900

Cu(II) 40 50 50 45 60

Ti(IV) 75 80 85 70 70

Ni(II) 50 60 50 65 60

Mn(II) 110 100 110 110 90

Zn(II) 85 95 80 75 75

Cd(II) 80 85 80 80 70

Pb(II) 120 125 130 120 110

Al(III) 150 160 160 155 140

Fe(III) 80 75 70 85 60

Bi(III) 160 170 165 160 140

Ga(III) 150 140 130 135 120

In(III) 120 125 125 110 110

Sc(III) 120 100 120 125 90

Cr(III) 130 135 120 90 100

Zr(IV) 150 160 160 150 145

Hf(IV) 140 130 145 140 145

Nb(V) 75 75 75 75 75

Ta(V) 75 75 75 75 75

V(V) 90 80 90 95 100

Mo(VI) 100 120 110 100 90

W(VI) 120 120 120 110 100

F- 200 180 190 200 180

HPO42- 300 280 290 300 300

C2O42- 130 140 150 130 120

SCN 250 260 260 240 245

Ascorbic acid 200 210 200 180 190

Tartaric acid 200 180 170 200 190

1. -

0.5 1.0

2.0 2.5 3.0 Co(II), ^g/ml

4.0

Fig. 5. Analytical determination of Co(II): 1 - Co-HATP-AP2, 2 -Co-HTP-AP2, 3 - Co-HTST-AP2, 4 - Co-HNTP-AP2 ; COP = (1.10-2.25)10-3 mol/ L-1, CAP = (0.92-1.24)- 10-3 mol/ L, X=540 nm, pH 4.0-6.0, SF-26, /=1.0 cm.

4

3

Table 3. Comparative characteristics of the methods for determining cobalt

Reagent (5) pH X, nm e-10-4 Beer's law range, ^gml-1 Ref.

1-hydroxy-2-naphthoic acid + aniline 6.0-8.0 575 1.08 0.25-110 [16]

diantypyrilmethane+naphthalene-2-sulfonic acid 0.5M HCl 615 1.9 20-150 [17]

^-methylisonitroasetophenone 6.8-7.8 380 2.3 0.1-4.0 [18]

4-(2-pyridylazo)resorcinol+xylometazoline hydrochloride 7.0-8.0 535 4.2 0-1.6 [19]

4-(2-pyridylazo)resorcinol+2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride 4.7 515 5.0 2.6 [20]

4-(2-thiazolylazo)resorcinol+2,3,5-triphenyl-2H-tetrazolium chloride 5.2-5.8 525 4.26 0.2-1.5 [21]

Nitrotetrazolium chloride 2.5-4.5 630 [22]

4-(2-thiazolylazo)resorcinol + zephyramine 6.7-10 550 3.42 2.0-5.0 [23]

4-(2-pyridylazo)resorcinol+1,4-diphenyl-l-(3 -phenylamino)-1H-1,2,4-triazolol 5.3 520 6.0 1.7 [24]

2,4-dihydroxyasetophenone 9.5 390 2.7 0.12-1.77 [25]

Bromopyrogallol red + Tiven 80 2.0 388 0.06 0.25-40 [26]

1-allyl-3- (5-chloropyridyl) 3.5 495 1.7 [27]

OP + AP see Table 1

Table 4. Results of cobalt determination in industrial and natural materials (n = 6, P = 0.95)

Found cobalt X + tpS / 4n , %; (Sr)

Reagent Analyzed material

Steel M 441 (0.012% Co) Steel HM^,5/M 627x (0.055% Co) Plant* Sewage water Bottom sediments

HATP-AP2 0.014±0.0071 (2.1±0.61)10-4 0.45±0.02 1.34±0.07

(0.057) (0.043) (0.024) (0.012)

htp-ap2 0.055±0.1200 (0.023) 0.485±0.083 (0.032)

htst-ap2 0.015±0.0011 (0.029) 1.30±0.09 (0.044)

hntp-ap2 0.012±0.0015 (0.036) 0.053±0.0019 (0.034) 0.512±0.01 (0.053)

nAP-TX* (9.43±0.56)10-4 (0.054) 1.29±0.05 (0.019)

^AM-HCK* 0.013±0.0011 (0.043) (8.95±0.47)10-4 (0.035) 0.490±0.050 (0.041)

OHK-An* 0.054±0.102 (0.016) (9.15±0.63)T0-4 (0.047) 1.26±0.05 (0.024)

* Note: The cobalt content in natural objects is in mg/kg; tetrazolium chloride; DAM - Diantypyrilmethane; Ni naphthalene acid; An - aninlin.

Conclusions

1. Mixed-ligand complexes of cobalt(II) with OP and Am have been studied by spectro-photometry. Extraction of mixed ligand complexes is maximum at pH 3.6-6.3. The optimal conditions for the formation and extraction of mixed-ligand compounds have been found.

2. The molar ratio of the reacting Co(II), OP and AP species is 1:2:2. The general formula

.R - 4-(2-pyridylazo)resorcinol; TX - 2,3,5-triphenyl-2H-- naphthalene-2-sulfonic acid; HNA - 1-hydroxy-2-

of the ternary complexes is [Co(OP)2](APH)2. They can be regarded as ion-associates between doubly charged anionic chelates [Co(OP)2] -and protonated AP species.

3. The developed method retains specific interaction of cobalt(II) with OP and AP to form a colored complex and has good sensitivity at room temperature. The proposed method has significant advantage over the other spec-trophotometric methods in terms of simplicity

and sensitivity. This proposed method provides good precision and accuracy. A procedure has been developed for extraction-spectrophotomet-ric determination of cobalt in various objects.

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KOBALTIN(П) HIDROFOB AMiN i§TiRAKINDA 2-HiDROKSiтiOFENOL УЭ ONUN TбRЭMЭLЭRI ЛЭ KOMPLEKS ЭMЭLЭGЭLMЭSi УЭ EKSTRAKSiYASI

N.A.Verdizadэ, §.ЭЛЬгаЫтоуа, G.V.Babayeva

Spektrofotometrik metodla коЬаНт hidrofob amin i§tirakinda oksitiofenol (OF) {2 -hidroksitiofenol (ИТБ) уэ опип tбrэmэlэri (2-hidroksi-5-amintiofenol (ИАТБ), 4-hidroksi-3-tiosulfotur§u (HTST), 4-hidroksi-3-tiolbenzoy tur§usu (ИТВТ), 4-nitro-2-hidroksitiofenolа (NHTF)} ilэ muxtэlifliqandh kompleks (MLK) этэ1э gэtirmэsi уэ ekstraksiyasl tэdqiq edilmi§dir. MLK этэ1э gэ1mэsi рИ 3.6-6.3 intervallnda ba§ verir. Komplekslэrin эmэ1эgэ1mэ уэ ekstraksiya §эшй, tэrkibi, fiziki-kimyэyi уэ ana1itik xassэ1эri muэyyэn edilmi§dir MLK ekstraktl kobaltln 0.05-3.2 mkq/ml qatlllq intervallnda Вег qanununa tabe olur. Yeni i§lэnilmi§ metodika muxtэ1if obyekt1эrdэ kobaltln ekstraksiyall-spektro-fotometrik tэyininэ tэtbiq edilmi§dir.

Адаг sдzlэr: kobalt, ekstraksiya, spektrofotometriya, ion-assosiat, hidrofob ammlэr, hidroksitiofenol.

КОМПЛЕКСООБРАЗОВАНИЕ И ЭКСТРАКЦИИ КОБАЛЬТА (II) С 2-ГИДРОКСИТИОФЕНОЛОМ И ЕГО ПРОИЗВОДНЫХ В ПРИСУТСТВИИ ГИДРОФОБНЫХ АМИНОВ

А.З.Залов, Н.А.Вердизаде, Ш.А.Ибрагимова, Г.В.Бабаева

Спектрофотометрическими методами изучены реакции образования разнолигандные комплексы кобальта (II) с окситиофенолом (ОР) {2-гидрокситиофенолом (ИТР) и его производными (2-гидрокси-5-аминтиофенол (ИАТР), 4-гидрокси-3-тиолсульфоновая кислота (ИTSA), 4-гидрокси-3-тиолбензойной кислоты (ИТВА), 4-нитро-2-гидрокситиофенола (ИКТР)} в присутствии гидрофобных аминов (Am). Оптимальный интервал кислотности, при котором оптическая плотность максимальна и постоянна, находится прирН 3.6-6.3. Определены условия образования и экстракции, состав, физико-химические и аналитические свойства комплексов. Экстракты ионных ассоциатов кобальта подчиняются основному закону светопоглощения при концентрациях 0.05-3.2 мкг/ мл. Разработана методика экстракционно-спектрофотометрического определения кобальта в разных объектах.

Ключевые слова: кобальт, экстракция, спектрофотометрия, ион-ассоциат, гидрофобные амины, гидрокси-тиофенол.