LIQUID – LIQUID EXTRACTION AND COMPLEXATION PROPERTIES ...shodhganga.inflibnet.ac.in/bitstream/10603/4671/8/08_chapter 3.pdf · LIQUID – LIQUID EXTRACTION AND COMPLEXATION PROPERTIES

CHAPTER 3

LIQUID – LIQUID EXTRACTION AND

COMPLEXATION PROPERTIES OF

THORIUM (IV) WITH TETRA

FUNCTIONALIZED

AZO-CALIX[4]PYRROLE DERIVATIVES

Liquid Extraction of Th[IV]

Chapter 3 Page 110

RESUME

A new series of calix[4]pyrrole derivatives bearing azo-moiety at the meso-

position of the macrocycles have demonstrated the ability for liquid-liquid extraction,

preconcentration and transport of Th(IV) across a liquid membrane. Various

significant extraction parameters such as effect of pH, effect of solvent and effect of

reagent concentration were investigated, which showed high affinity and selectivity

towards Th(IV) in the presence of large quantities of associated metal ions. The

wavelengths of maximum extraction (λmax) and molar absorptivity (ε) have also been

determined. The stoichiometry of complex was evaluated by Job’s plot method, linear

concentration range obeying Beer’s law, effect of diverse-ions have also been studied.

Liquid membrane transport studies of Th(IV) were carried out from source to the

receiving phase under controlled conditions and a mechanism of transport is

proposed. The validity of the proposed method was checked by determination of

analyte ions in certain standard and natural geological samples.


Chapter 3 Page 111

TABLE OF CONTENTS

1. Introduction 112

2. Experimental Section 114

2.1. Instruments and measurements 114

2.2. Chemicals and reagents 115

2.3. UV/Vis titrations for preliminary complexation study 117

2.4. General procedure for the liquid-liquid extraction of Th(IV) 118

2.5. Liquid membrane transport studies 118

3. Results and Discussion 120

3.1. Preliminary complexation study 120

3.2. Spectral characteristics of Th(IV)–azo-calix[4]pyrrole complex 121

3.3. Effect of variables on the extraction 121

3.3.1. pH and shaking time for extraction

3.3.2. Effect of solvent

3.3.3. Reagent (DHPDPCP) concentration

3.4. Stoichiometry of complex 122

3.5. Liquid membrane transport studies 123

3.6. Preconcentration of Th(IV) 124

3.7. Effect of diverse ions 124

3.8. Applications 125

Conclusion 138

References 139


Chapter 3 Page 112

1. INTRODUCTION

Considerable effort has been focused on the preparation of supramolecular

host systems with the capability of recognizing specific chemical species through

weak, non covalent interactions [1]. The design and synthesis of a variety of host

molecules is a challenging topic in the field of molecular recognition chemistry

because of the promising new functions of these novel compounds or the fantastic

features attainable by forming supramolecular complexes from the host and guest

molecules [2]. Among representatives of a class of compounds that are the subject of

supramolecular chemistry, calixpyrroles are gaining increasing interest as new

macrocyclic receptor molecules [3]. Pioneering work in the area of calix[4]pyrroles

has been done by Sessler and co-workers, has evidenced that calix[4]pyrroles can

effectively be employed as suitable anion binding agents and may be used for the

detection and sensing purposes in new separation technologies [4-10]. The above

statement is furthered by the availability of various post macrocyclization

modifications [11, 12]. Synthetic chromo-ionophores that give rise to specific colour

changes on selective complexation with cations and anions, have attracted

considerable attention as efficient spectrophotometric analytical reagents for the

detection of particular species as well as the design of supramolecular devices having

recognition and optical sensing functions [13, 14]. Generally, the development of

most chromogenic reagents based on calixarenes have been achieved by attaching a

chromogenic moiety/chelating moiety. There have been few reports wherein

macrocycles such as calix[4]arene [15], calix[4]resorcinarene [16], thiacalix[4]arene

[17] and crown ether [18] are used as components for the preparation of azo dyes, but

the research in the area of calix[4]pyrrole based dyes [19] is still in infancy.


Chapter 3 Page 113

Detection and sensing of heavy, transition and rare earth metal ions via

synthetic receptors are topics of recent interest in supramolecular chemistry because

of their significant value in chemical, biological and environmental assays [20]. The

main source of Thorium Th(IV) is monazite sand, mainly associated with cerium,

lanthanum, yttrium and iron etc. Thorium is used in a wide array of products and

processes, for example in the production of ceramics, carbon arc lamps, alloys, in

mantles and also as a source of nuclear energy [21]. For all of these purposes,

development of analytical methodologies for separation and determination of these

elements becomes essential. Several analytical methods ranging from classical

methods to modern instrumental analytical techniques were developed for extraction

and determination of Th(IV) [22]. Although several preconcentration techniques are

available for the enrichment of thorium, the two most common traditional methods

are liquid–liquid extraction and ion exchange. Liquid–liquid extraction offers the

advantages of fast kinetics, high capacities and high selectivity [23]. There are several

reagents (thoron-I, arsenazo-III, arsenazo-I, p-bromochlorophosphoazo,

tribromoarsenazo etc.) that have been reported for spectrophotometric determination

of Th(IV) [24-26]. A large number of extranctants such as tributyl phosphate (TBP),

trioctyl phosphine oxide (TOPO), cyanex923 (a mixture of four trialkyl phosphine

oxides), tris-(2-ethyl hexyl) phosphate (TEHP)6 and triphenyl phosphine oxide

(TPPO) were reported for extraction of thorium [27].

The macrocycles can form the host-guest complex and can be used for the

complexation with several metal ions, however the complexation with Th(IV) is very

little [28]. Although a lot of chromogenic reagents [29] for detection of transition

metals have been reported, none of the reagents were prepared by attaching a

chromogenic moiety (–N=N–) at the meso-position of a macrocyclic compound, such


Chapter 3 Page 114

as calix[4]pyrrole. Recently, Chauhan et al. [30] have developed two novel octa

methyl calix[4]pyrroles by introducing the chromogenic group at two different

positions and studied them as potential anion binders due to their rich and unique

complexation behaviour.

In the present work, a preliminary complexation study of synthesized azo

calix[4]pyrrole dyes towards various metal ions [U(VI), Th(IV), La(III) and Ce(III)]

have been investigated by UV/Vis spectrophotometry. It was observed that only

Th(IV) to a larger extent and other metal ions to a smaller extent showed

complexation behaviour with all the dyes and out of all the dyes used, only meso-

tetra(methyl) meso-tetra{(3, 5-dihydroxy phenyl)- 4(2-diazenyl phenol)} calixpyrrole

2f (DHPDPCP) exhibit best sensitivity and selectivity for Th(IV). Therefore,

(DHPDPCP) was selected for the development of sensitive and selective

spectrophotometric method for the determination of Th(IV) by liquid-liquid

extraction. The extracted thorium complexes have been determined simultaneously by

spectrophotometry/ICP-AES. Various parameters for the extraction have been

studied. The validity of the proposed method was tested by analysing this Th(IV) in

certain natural and geological samples.

2. EXPERIMENTAL SECTION

2.1. Instruments and measurements

Inductively coupled plasma-atomic emission spectrophotometer Arcos model

by Spectro, Germany, with the plasma scan multitasking computer and a peristaltic

pump was used under optimum working conditions: R.F. Generator : Maximum of 1.6

KW, 27.12 MHz; Plasma: Radial plasma, having capability to analyse aqueous

solutions with high dissolved solid content; Spectrometer : Wavelength Range : 10


Chapter 3 Page 115

nm to 770 nm, Resolution : approx. 9 pico meter, having capability to scan full

spectrum; Detector : Charge Coupled Devices (CCD); Vertical Torch assembly

having fully demountable quartz torch with individual tubes; Nebulizers : Concentric,

cross flow, organic nebulizer (hydrocarbons, solvents) ; Spray Chambers : HF

Resistant cyclonic chamber and hydrocarbon solution spray chamber. UV/Vis

absorption studies were carried out on a JASCO 570 UV/VIS/NIR spectrophotometer

using 10 mm quartz cells. All pH measurements were performed using an Elico

digital pH meter, model L1 614, equipped with a combined pH electrode.

2.2. Chemicals and reagents

All the chemicals used were of analytical grade from E. Merck or BDH. All

aqueous solutions were prepared with quartz distilled deionized water, which was

further purified by a Millipore Milli-Q water purification system (Millipack 20, Pack

name: Simpak 1, Synergy) throughout the entire study. The pH was adjusted with the

following buffer solutions [31] : PO4-3/HPO4

-2 buffer for pH 2.0 and 3.0; CH3COO-1

/CH3COOH buffer for pH 4.0 and 6.0; HPO4-2/H2PO4

-1 buffers for pH 7.0 and 7.5.

Standard stock solutions (1000 μg mL-1) of U(VI), Th(IV), La(III) and Ce(III) were

prepared as given below.

Standard Stock Solutions

U(VI): Dissolve 0.2109 gm UO2(NO3)2.6H20 in water containing 1 mL

concentrated HNO3 and dilute upto 100 mL with water in volumetric flask.

Th(IV): Dissolve 0.25 gm Th(NO3)4.4H2O in water containing 1 mL

concentrated H2SO4 and dilute upto 100 mL with water in volumetric flask.

La(III): Dissolve 0.2345 gm La(NO)3.6H2O in water containing 1 mL



Chapter 3 Page 116

Ce(III): Dissolve 0.4541 gm Ce(NO3)3.6H2O in water containing 1 mL


Working solutions were subsequently prepared by appropriate dilution of the

stock solutions. Their final concentrations were then standardized

spectrophotometrically [32].

The six azo-calix[4]pyrrole dyes (Figure 1) were synthesized and

characterized as described in Chapter 2 and their stock solutions (0.1%) were

prepared in Iso-amyl alcohol and DMSO. Working solutions were subsequently

prepared by appropriate dilution of the stock solutions.

Figure 1. Synthesized azo-calix[4]pyrrole dyes :

NH

CH3

CH3 A

OH OHN

NR1

R2

4

Azo-calix[4]pyrrole dyes

a : R1= H , R2= -CH3

b : R1= -NO2 ,R2= -NO2

c : R1= H ,R2= -OH

d : R1= H , R2= -Cl

e : R1= H , R2= -NO2

f : R1= -OH , R2= H


Chapter 3 Page 117

Figure 2. Cyclic structure of dye 2f (DHPDPCP) used for liquid–liquid extraction of

Thorium.

2.3. General Procedure for preliminary complexation study by UV/Vis

spectrophotometer

Preliminary complexation studies for various azo-calix[4]pyrrole dyes with

rare earth metal ions were carried out at 25ºC using a JASCO 570 UV/VIS/NIR

spectrophotometer. Metal solutions [U(VI), Th(IV), La(III) and Ce(III)] were directly

injected by a precise syringe (Hamilton, 10 μL) into the cuvette having the solution of

azo-calix[4]pyrrole dyes in DMSO (2a-2f). The resulting solutions were allowed to

attain equilibrium for one minute before recording the spectra. Usually, 0.02 M (10

μL) metal solutions were added to 10-5 M solutions (3 mL) of azo-calix[4]pyrrole dyes

(2a-2f). The spectrophotometric data were collected over the range 200-800 nm for all

azo-calix[4]pyrrole dyes .

NHNH

NH

CH3

CH3

CH3

CH3

OHHOOH

HO

OHHOOH

HON

N

N

NN

N

N

NOH

OH OH

OH


Chapter 3 Page 118

2.4. General procedure for the liquid-liquid extraction of Th(IV)

An aqueous phase containing not more than 50 µg of Th(IV) was transferred

into a 25 mL separatory funnel and desired pH, 5.5 was adjusted with the appropriate

buffer solutions in a total volume of 10 mL. The mixture was shaken with 6 mL of

0.015 % reagents (azo-calix[4]pyrrole dyes) in Iso-amyl alcohol. The metal-reagent

complex was extracted into the organic phase. To ensure complete recovery, the

extraction was repeated with 2 mL of reagent solution; the organic extract was

separated, dried over anhydrous sodium sulphate and transferred into a 10 mL

volumetric flask. The combined extracts and washings were diluted to the mark (10

mL) with Iso-amyl alcohol. The absorbance of the organic phase was measured at 498

nm.

The concentration of the metal ion extracted into the organic phase [Th+4](org)

as complex was estimated by [Th+4](org) = [Th+4](aq, int) - [Th+4](aq), where [Th+4](aq, int)

is the initial concentration of the metal ion in the aqueous phase.

The percent extraction (%E), was calculated by

%E = 100

int),(4

)(4

aq

org

ThTh

The extracted thorium complex with azo-calix[4]pyrrole dye in Iso-amyl

alcohol after appropriate dilution was determined by spectrophotometry/ICP-AES.

2.5. Liquid membrane transport studies

Transport of Thorium was carried out in a specially fabricated glass assembly

as shown in Figure 3. The reaction cell was 6.6 cm in inner diameter and 9.0 cm in

height with a total capacity of 305 mL. U-tube (2.0 cm diameter, 20 cm length) was

fused from the base of the cell. The height of the tube inside the cell was 4.0 cm from


Chapter 3 Page 119

the basal plane. The transport experiments were performed with 50.0 mL of 1.0 10-5

M Th(IV) solutions at pH 5.5 from the source phase to the 50.0 mL, 0.1 M, HCl as the

receiving phase. The liquid membrane consisted of 75 mL of 1.0 10-5 M reagent (2f)

in Iso-amyl alcohol. A synchronous motor (200 rpm) provided constant reproducible

stirring from the top. The amount of thorium transported from the source phase to the

receiving phase was measured by spectrophotometry/ICP-AES. The transport data

were the average of 5 runs with an experimental error of less than 2%.

Figure 3. Apparatus for transport studies

Source Phase (SP) : 50.0 mL, pH 5.5, 1.0 x 10-5 M Th (IV)

Liquid Membrane Phase (LMP) : 75.0 mL, 1.0 x 10-5 M reagent (2f)

in Iso-amyl alcohol

Receiving Phase (RP) : 50.0 mL, 0.1 M HCl


Chapter 3 Page 120

3. RESULTS AND DISCUSSION

3.1. Preliminary complexation study

To examine the complexation of newly synthesized azo dyes with various rare

earths like U(VI), Th(IV), La(III) and Ce(III), titrations were carried out using

UV/Vis spectrophotometer.

The spectral bands (λmax) of the reagents (2a-2f) and their complexes were

measured using UV-Vis spectrophotometer. The spectra of the reagents are

characterized by an intense band in the range at 380-450 nm attributed to a n - π*

transition (–N=N–). In the spectra of their metal complexes, a new conspicuous

absorption band appears in the range of 400-500 nm. The results obtained for optical

response (∆λ) = [λmax(complex) - λmax(reagent)], are summarized in Figure 4.

The experimental results showed that the synthesized azo-calix[4]pyrrole dyes

exhibited optical response for each metal ion used for complexation study but it was

found maximum for Th(IV). To further check the selectivity for Th(IV), out of all

azocalixpyrrole dyes, used for complexation, only, azo dye 2f (DHPDPCP) gave

exceptional results and showed clear selectivity for Th(IV). These results indicated

that azo groups which may be circularly arranged on the meso-position of

calix[4]pyrrole cavity, construct novel cyclic metal receptors. These reasons were

sufficient to study the selective behaviour of reagent 2f (DHPDPCP) for Th(IV) by

liquid-liquid extraction.

In order to obtain the optimum conditions for the maximum extraction of

Th(IV) by 2f (DHPDPCP), different factors affecting this process have been studied


Chapter 3 Page 121

3.2. Spectral characteristics of Th(IV)-azo-calix[4]pyrrole complex

The synthesized azo-calix[4]pyrrole dyes (2a-2f) were used for the extraction

and spectrophotometric determination of Th(IV). It was observed that among all of

the synthesized azo-calix[4]pyrrole dyes (2a-2f), 2f (DHPDPCP) was most sensitive

for the Th(IV) (Table 1). The complexation of Th(IV) with DHPDPCP was studied

under optimum conditions of pH, shaking time, solvent and reagent (DHPDPCP)

concentration. The maximum absorbance of the dark red coloured complex was

measured at 498 nm and showed a bathochromic shift of 80 nm from that of the

reagent blank (Figure 5). The molar absoptivity (ε) was found to be 22,000 L mol-1

cm-1. The system obeys Beer’s law in the range of 0.5-10 µg mL-1 of Th(IV).

3.3. Effect of variables on the extraction

3.3.1. pH and shaking time for extraction

The pH of the medium is a significant factor in extraction process. A series of

experiments were carried out to study the effect of pH on the liquid-liquid extraction

of Th(IV), by DHPDPCP in Iso-amyl alcohol and the results are presented in Table

2. Maximum extraction of Th(IV) complex was obtained in range of pH 5.0 - 5.5

(Figure 6); at the lower and higher pH the extraction was incomplete. This may be

because the reagent remains protonated at pH lower than 4.5 and hydrolysis of

Thorium ions at pH higher than 6.5. So, pH 5.5 was chosen for the extraction of

Th(IV).

The extraction of Th(IV) was examined for various times of equilibration. The

extraction with 5, 10, 15 and 20 minutes of shaking was 96.0%, 99.1 %, 99.1 % and

99.3% respectively, hence, a 10 minute time of equilibrium was used in all the


Chapter 3 Page 122

experiments. The extraction was not affected by further shaking, indicating that the

equilibrium state had been attained.

3.3.2. Effect of diluents

The Th(IV)-DHPDPCP complex was extracted with various solvents like

ethyl acetate, chloroform, toluene, benzene, dichloromethane, carbon tetrachloride

and Iso-amyl alcohol. As compared to other solvents the molar absorptivity in Iso-

amyl alcohol was found to be maximum therefore it was chosen to be the solvent for

quantitative extraction (Table 3).

3.3.3. Reagent (DHPDPCP) concentration

The influence of DHPDPCP was studied by extracting a fixed amount of

Th(IV) with varying amounts of reagent (DHPDPCP) at 5.5 pH. A 6 mL, of 0.015%

DHPDPCP was found to be sufficient for the quantitative extraction of Th(IV)

whereas, the extraction was incomplete at the lower concentration of DHPDPCP

(Table 4). The excess of the reagent had no adverse effect on the extraction of

Th(IV).

3.4. Stoichiometry of complex.

The stoichiometric ratio of the Th(IV) complex was determined by the

modified Job’s method of continuos variation. The absorbance of complex Ac of a

series of solution having different concentration ratios of thorium ion (Th)(IV) a and

DHPDPCP b, keeping total concentration (a+b) constant, was measured at 498nm.

The absorbance of b was substracted from the observed absorbance Ac to obtain the

true absorbance ΔA.

ΔA = Ac-Ab


Chapter 3 Page 123

ΔA values were plotted against the molar ratio of Th(IV) ion a/a+b (Figure

7) . The maximum value for ΔA was clearly obtained at a/a+b = 0.65, indicating 2 : 1

stoichiometric ratio of Th (IV) and DHPDPCP. The accuracy of this result is possible

only if a single complex is formed. To verify this, measurements were taken at

different selected wavelength, which gave same value for a/a+b ratio.

To get more information about the nature of the extracted complex, the extract

was evaporated to dryness. A known weight of the dry complex was digested with a

nitric acid. It was centrifuged and after appropriate dilution the thorium content was

determined by ICP-AES, which also confirmed 2:1 (M : L) complex.

3.5. Liquid membrane transport studies

The transport of Th(IV) through the membrane containing 1.0 X 10-5 M,

DHPDPCP from source phase containing 1.0 x 10-5 M, Th(IV) to the receiving phase

of 1.0 M HCl was carried out. As evident from the Figure 8 the concentration of

Th(IV) in the source phase starts decreasing continuously and it took about 25

minutes to transport half of the Th(IV) from source phase to receiving phase (curve

A). On the other hand, concentration of Th(IV) in the receiving phase starts increasing

as shown in the (curve B). Therefore, it is clear that Th(IV) moved from the source to

receiving phase through the liquid membrane. Based on these facts and knowledge

obtained by the extraction equilibria, the proposed mechanism of transport of thorium

through the liquid membrane of DHPDPCP is as shown in Figure 9. The carrier in

the membrane reacts with Th(IV) in the source phase at the interface of these phases

and forms a complex [H4(Th+4)2L-8] while releasing 8 moles of proton into the source

phase. On the other hand, interface of the membrane and the receiving phase of the


Chapter 3 Page 124

complex reacts with 8 moles of protons while releasing 2 moles of Th(IV) in the

receiving phase.

3.6. Preconcentration factor of Th(IV)

The concentration of Th(IV) in natural water samples is too low for its direct

determination. Therefore, preconcentration or enrichment step is necessary to bring

the sample to the detectable limits of existing instrument method. The method was

studied for the preconcentration of Th(IV) in terms of its preconcentration factors.

The preconcentration study was carried out by extracting 20 μg Th(IV) in

1000 mL aqueous phase with 10 mL of 0.015% DHPDPCP in Iso-amyl alcohol . To

evaluate the efficiency of preconcentration, expressed as recovery, the concentration

of Th(IV) in organic phase and the aqueous phase was determined by ICP-AES .

Quantitative determination was possible with recovery up to 97-98% with a

preconcentration factor 100.

3.7. Effect of diverse ions

The extraction of single metal ion under controlled condition gives an

indiciation of potential sensitivity of the proposed method. In order to examine the

sensitivity and selectivity of the present method, the influence of alkali, alkaline

earths, transition metals and rare earths on the extraction of Th(IV) under its optimum

extraction conditions was studied. The tolerance limit was set as the amount of

foreign ion causing not more than ±2% change in the recovery of Th(IV). The results

presented in Table 5 indicate that Th(IV) can be quantitatively extracted in the

presence of large number of foreign ions including rare earth elements. Thus, the

method developed is specific for Th(IV).

solutionfeedinmetalofionconcentratInitialsolutionstrippinginmetalofionConcentratPF


Chapter 3 Page 125

3.8. Applications

Determination and Recovery of Th(IV) from Standard samples

Standard rock samples obtained from United States Geological Survey

(USGS), monazite sand, rocks were analysed to test the reliability of the present

method results are presented in Table 6. Matrix interference was verified by

comparison of the slopes of the calibration graphs with that using standard addition

method. The precision of preconcentration procedure when combined with ICP-AES

was expressed as relative standard deviation of 1.4 % with a recovery up to 98%.

.


Chapter 3 Page 126

Table 1. Spectral characteristics of azo-calix[4]pyrrole dyes for the

extraction of Th(IV).

Th(IV) : 4 mL, 25 μg mL-1

pH : 5.5

Reagent : 0.015 % Azo-calix[4]pyrrole dyes

Solvent : Iso-amyl alcohol

No Azo-calix[4]pyrrole based dyes λ max nm

Colour of

Complex

Molar absorptivity

(L mol-1 cm-1)

2a meso-tetra(methyl) meso-tetra{(3, 5-dihydroxy phenyl)- 4-(4-methyl

phenyl diazene)} calixpyrrole 450 Red 14,385

2b

meso-tetra(methyl) meso-tetra{(3, 5-dihydroxy phenyl)- 4-(2,4-

dinitrophenyl diazene)} calixpyrrole

473 Red 11,634

2c meso-tetra(methyl) meso-tetra{(3,

5-dihydroxy phenyl)- 4-(4-diazenylphenol)} calixpyrrole

481 Dark Red 18,987

2d

meso-tetra(methyl) meso-tetra{(3, 5-dihydroxy phenyl)- 4-chlorophenyl diazene)}

calixpyrrole

468 Red 14,305

2e

meso-tetra(methyl) meso-tetra{(3, 5-dihydroxy phenyl)- 4-nitrophenyl diazene)}

calixpyrrole

479 Red 16,846

2f meso-tetra(methyl) meso-tetra{(3,

5-dihydroxy phenyl)- 4-(2-diazenyl phenol}) calixpyrrole

498 Light Pink 22,000


Chapter 3 Page 127

Table 2. Effect of pH on the extraction of Th(IV) with DHPDPCP complex.


Reagent : 0.015 % DHPDPCP


λmax : 498 nm

pH % of Extraction Molar absorptivity

(L mol-1 cm-1)

2.0 11 2,420

2.5 24 5,280

3.0 36 7,920

3.5 47 10,340

4.0 61 13,420

4.5 70 15,400

5.0 78 17,160

5.5 100 22,000

6.0 63 13,860

6.5 45 9,900

7.0 13 2,860


Chapter 3 Page 128

Table 3. Effect of diluents on the extraction of Th(IV)-DHPDPCP complex.



pH : 5.5

λmax : 498 nm

Solvent Dielectric constant Molar absorptivity

(L mol-1 cm-1)

Extraction

(%)

Toluene 2.30 - -

Benzene 2.28 - -

Carbon tetrachloride 2.20 - -

Dichloromethane 8.90 7,040 32

Chloroform 4.80 11,220 51

Ethyl acetate 6.40 14,080 64

Iso-amyl alcohol 15.3 22,000 100


Chapter 3 Page 129

Table 4. Effect of reagent (DHPDPCP) concentration for the extraction of Th(IV)



pH : 5.5


λmax : 498 nm

DHPDPCP

(0.015%)(mL) Colour of Complex

Molar absorptivity

(L mol-1 cm-1)

1 yellow 11,634

2 yellow 14,560

3 Red 18,653

4 Red 20,865

5 Red 22,000

6 Red 22,000

7 Red 21,980

8 Red 21,973

9 Red 21,973

10 Red 21,972


Chapter 3 Page 130

Table 5. Effect of diverse ions on the extraction of DHPDPCP – Th(IV) complex.

Th(IV) : 10 mL, 3 µg mL-1

pH : 5.0

Reagent : 0.015% DHPDPCP


λmax : 498 nm

Ions Added as Amount Added (mg)

Recovery of Thorium (ppm)

Spectrphotometry ICP-AES

Ag+ AgNO3 65 3.0 3.0

Be+ BeCl2 70 2.94 2.95

Pb+2 Pb(NO3)2 70 2.93 2.92

Mn+2 MnCl2 65 2.98 2.99

Ni+2 NiCl2 75 2.97 2.97

Cu+2 CuCl2 75 2.98 2.98

Zn+2 ZnCl2 80 2.99 2.98

Cd+2 CdCl2 75 2.98 2.99

Hg+2 HgCl2 60 3.00 3.00

Pd+2 PdCl2 65 2.98 2.99

Al+3 AlCl3 65 2.97 2.98

Sn+2 SnCl2 70 2.99 2.98

Zr+4 Zr(NO3)4 80 2.98 2.99

Mo+6a (NH4)6Mo7O24 60 3.00 2.99

UO2+2 UO2(NO3)2 75 2.90 2.91

V+5b NH4VO3 80 2.98 2.97

Fe+3 FeCl3 85 2.99 2.98

Cr+3 Cr2O3 75 2.98 2.97

Mg+2 MgCl2 65 2.98 2.99


Chapter 3 Page 131

Table 6. Analysis of Th(IV) in standard samples from the United States

Geological Survey (USGS) and monazite sand.

Metal Ions Th(IV)

Sample Certified Amount(µg L-1)

Amount Found(µg L-1)

Natural geological samples

Monazite Sand, 8.41±0.009 8.40±0.011

Travancore, India (%)

USGS:BCR-1 (µg.gm-1) 6.1 ±0.009 6.1 ±0.007

USGR:GSP-1 (µg.gm-1) 105 ±0.01 104 ±0.025


Chapter 3 Page 132

Figure 4. Preliminary complexation of cations as a function of the

nature of the ligands.


Chapter 3 Page 133

Figure 5. Comparative spectra of reagent (DHPDPCP) and its complex

with Th(IV) in Iso-amyl alcohol

0

0.4

0.1

0.2

0.3

280 400 600

Abs

DHPDPCP

Th(IV) - DHPDPCP


Chapter 3 Page 134

Figure 6. Effect of pH on the extraction

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8

(%) E

xtra

ctio

n

pH

Effect of pH


Chapter 3 Page 135

Figure 7. Job’s plot for the mixture of DHPDPCP and Th[IV]

00.010.020.030.040.050.060.070.08

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

∆A

Mole fraction

Stoichiometry


Chapter 3 Page 136

Figure 8. Transport profile of Th(IV) through the liqiud membrane

containing DHPDPCP at 30°C.

00.5

11.5

22.5

33.5

4

0 20 40 60 80

µg/m

L

Time (minutes)

Transport Profile

RPSP


Chapter 3 Page 137

Figure 9. Proposed mechanism for transport of Th(IV) through a liquid membrane

containing DHPDPCP.

SP LMP RP

2 Th+4

8H+

H12 L

H4(Th+4)2L-8

2 Th+4

8H+

SP : Source phase;

LMP : Liquid membrane phase;

RP : Receiving phase


Chapter 3 Page 138

CONCLUSION

Six reagents synthesized by the introduction of azo (-N=N-) functionality on

the calix[4]pyrrole macrocycle resulted in a chelating system which was used

successfully for the liquid-liquid extraction and transport of Th(IV) across a liquid

membrane of iso-amyl alcohol. The described solvent extraction method is simple,

sensitive and specific for the determination of Th(IV) ion in presence of large

quantities of associated metal ions. The binding of Th(IV) with azo-calix[4]pyrrole in

the ratio 2:1 (Metal : Ligand) indicates the greater utility of the reagent. The results

obtained from the determination of analyte ions in certain standard and natural

geological samples established the reliability, simplicity and robustness of the

method.


Chapter 3 Page 139

REFERENCES

1. (a) Rebek, J. Acc. Chem. Res. (1984), 17, 258. (b) M. Takeuchi; M. Ikeda; A.

Sugasaki; S. Shinkai, Acc. Chem. Res. (2001), 34, 865. (c) J. L. Atwood; J.

W. Steed, Encyclopedia of Supramolecular Chemistry; Marcel Dekker: New

York, (2004); Vols. 1-2.

2. Z. Asfari, V. Bohmer, J. Harrowfield, and J. Vicens, Calixarene (2001), Ed.;

Kluwer Academic Publishers, (2001), Chapter 34, 627.

3. P. A. Gale, P. Anzenbacher, Jr.; J. L. Sessler, Coord. Chem. Rev., (2001),

222, 57.

4. P. A. Gale, J. L. Sessler, V. Kra’l, V. Lynch, J. Am. Chem. Soc.,(1996),

118, 5140.

5. W. E. Allen, P. A. Gale, C. T. Brown, V. M. Lynch, J. L. Sessler, J. Am.

Chem. Soc., (1996), 118, 12471.

6. P. A. Gale, J. L. Sessler, W. E. Allen, N. A. Tvermoes, V. Lynch, Chem.

Commun. (1997), 665.

7. R. Custelcean, L. H. Delmau, B. A. Moyer, J. L. Sessler, W.S. Cho, D.

Gross, G. W. Bates, S. J.; Brooks, M. E. Light, P. A. Gale, Angew. Chem.,

Int. Ed., (2005), 44, 2537.

8. P. A. Gale, J. L. Sessler, V. Kr’al, Chem. Commun., (1998), 1.

9. K. A. Nielsen, W.S. Cho, J. O. Jeppesen, V. M. Lynch, J. Becher, J. L.

Sessler, J. Am. Chem. Soc., (2004), 126, 16296.

10. H. Miyaji, D. An, J. L. Sessler, Supramol. Chem., (2001), 13, 661.

11. J. P. Hill, A. L. Schumacher, F. D’Souza, J. Labuta, C. Redshaw, M. R. J.

Elsegood, M. Aoyagi, T. Nakanishi, K. Ariga, Inorg. Chem., (2006), 45,

8288.

12. (a) K. Liu, Y. Guo, J. Xu, S. J. Shao, S. X. Jiang, Chin. Chem.Lett.,(2006),

17, 387. (b) R. Nishiyabu, M. A. Palacios, W. Dehaen, P. Anzenbacher Jr., J.

Am. Chem. Soc.,(2006), 128, 11496.

13. C. D. Gutsche, Calixarenes Revisited; Monographs in Supramolecular

Chemistry Ed.; J. F. Stoddart, RSC, Cambridge, (1998), 149.

14. V. Bohmer, and J. Vicens, Calixarenes; A Versatile Class of Macrocyclic

Compounds Ed.; Kluwer Academic Publishers, Dordrecht, (1991), 127.


Chapter 3 Page 140

15. (a) F. Oueslati, I. Dumazeat-Bonnamour and R. Lamartine, New J. Chem.,

(2003), 27, 644. (b) O. O. Karakus, and H. Deligoz, J. Incl. Phenom.

Macrocycl. Chem., (2008), 61, 289. (c) H. Deligoz, J. of Incl. Phenom.

Macrocycl. Chem., (2006), 55, 197.

16. (a) O. Manabe, K. Asakura, T. Nishi, and S. Shinkai, Chem. Lett., (1990),

1219. (b) V. K. Jain, and P. H. Kanaiya, J. Incl. Phenom. Macrocycl. Chem.,

(2008), 62, 111.

17. (a) P. Lhotak, J. Moravek, and I. Stibor, Tetrahedron Lett., (2002), 43, 3665.

(b) F. Oueslati, I. Dumazet-Bonnamour, and R. Lamartine, Supramol. Chem.,

(2005), 17(3), 227.

18. (a) E. Luboch, E. Wagner-Wysiecka, M. Fainerman-Melnikova, L. F.

Lindoy, and J. F. Biernat. Supramol. Chem., (2006), 18(7), 593. (b) U.

Harikrishnan, and S. K. Menon, Dyes and Pigments, (2008), 77(2), 462.

19. (a) R. Gu, S. Depretere, J. Koteck, J. Budka, E. Wangner-wysiecka, J. E.

Biernat, and W. Dehaen, Org. Biomol. Chem., (2005), 3, 2921. (b) R.

Nishiyabu, M. A. Palacious, W. P. Dehaen, and P. Jr. Anzenbacher, J. Am.

Chem. Soc., (2006), 128, 11496.

20. V.K.Jain, S.G. Pillai, R. A. Pandya, Y.K. Agrawal and P.S. Shrivastav,

Analytical Sciences, (2005), 21, 129.

21. M. Karve, C. Gaur, J. Radioanal. Nucl. Chem., (2006), 270(2), 461.

22. M. R. Buchmeiser, Rev. Anal. Chem., (2001), 20(3), 161.

23. C. J. Lewisin : Recent Developments in Separation Science, N.N. Li (Ed.),

clevand: CRC Press, (1972), 2, 47.

24. J. A. Dalzeil and A. K. Slawinski, Talanta, (1972), 19, 1190.

25. T. Yamamoto, Anal.Chim.Acta., (1973), 65, 63.

26. H. H. Perkampus ( translated by H. C. Grinter and T. L. Threlfall), “UV-VIS

Spectroscopy and its Applications” (1982), Springer-Verlag, Newyork.

27. (a) V. I. Volk, A. Yu.Varkhrushin, S.L. Mamaev , J. Radioanal. Nucl.

Chem., (2000) , 46, 697. (b) E. Hesford, H. A. Mckay, D. Scargill, J. Inorg.

Nucl. Chem., (1957) , 4 ,321. (c) J. C. Guyon and B. Madison , Mikrochim.

Acta., (1975), 1, 117. (d) Y. M. Reza and E. M. Ebrahim, Iranian J. Chem.

Eng., (2003), 22, 71. (e) B. Gupta, P. Malik, A. Deep , J. Radioanal. Nucl.

Chem., (2002), 251, 451. (f) G. S. Desai and V. M., Shinde, J. Radioanal.


Chapter 3 Page 141

Nucl. Chem., (1991), 154, 227. (g) N. G. Bhilare and V. M. Shinde, J.

Radioanal. Nucl. Chem., (1994), 185, 243.

28. G. W. Gokel (ed.) “Crown Ethers and Cryptand” (1991). The Royal Society

of Chemistry. London.

29. (a) T. Tilki, I. Sener, F. Karci, A. Gulce and H. Deligoz, Tetrahedron,

(2005), 61, 9624. (b) L. Lua, S. Zhub, X. Liua, Z. Xiec, and X. Yanc, Anal.

Chim. Acta., (2005), 535, 183.

30. B. Garg, T. Bisht and S. M. S. Chauhan, New J. Chem., (2010), 34, 1251.

31. J. A. Dean, Lange’s Handbook of Chemistry, 15th Ed., McGraw-Hill, New

York, (1999).

32. Z. Marczenko, Spectrophotometric Determination of Elements, Ellis-

Horwood Ltd., Chichester, (1976).

Documents

LIQUID – LIQUID EXTRACTION AND COMPLEXATION PROPERTIES ...shodhganga.inflibnet.ac.in/bitstream/10603/4671/8/08_chapter 3.pdf · LIQUID – LIQUID EXTRACTION AND COMPLEXATION PROPERTIES