DOI : 10.5281/zenodo.21372777
- Open Access
- Authors : Sanjay Kumar
- Paper ID : IJERTV15IS070208
- Volume & Issue : Volume 15, Issue 07 , July – 2026
- Published (First Online): 15-07-2026
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Studies on Synergism in the Extraction of Fe (III) with Anthranilic Acid in the Presence of Heterocyclic Amines using Spectrophotometric Technique
Sanjay Kumar #
#Associate Professor, Department of Chemistry, Patna Science College, Patna University, Patna, INDIA
ORCID iD: https://orcid.org/0000-0003-0617-1743
ABSTRACT: Using Solvent Extraction Technique extraction of Fe(III) with anthranilic acid in the presence of pyridine and b-picoline into Benzene have been studied with the help of Spectrophotometric method. Mathematical computation based on equilibrium treatment for Distribution Coefficient has been employed on the experimental data. The effect of various variables such as pH of the aqueous phase, metal ion concentration, anthranilic acid concentration, and base concentration have been reported. Synergistic effect of pyridine and b-picoline in the extraction of Fe(III) with anthranilic acid have been established and the effectiveness of pyridine and b-picoline as synergist has been compared. The most probable composition of the synergistic adduct as [Fe(OH)2A.2B] where A = anthranilate ion and B = pyridine or b-picoline, has been postulated on the basis of Slope analysis method.
Keywords: Solvent extraction, Synergism, Spectrophotometric method, Anthranilic acid, Pyridine, b-picoline, Slope analysis method
-
INTRODUCTION
Solvent extraction, as one of the most useful separation techniques, can be safely extended from microlevels to macro-concentrations. In solvent extraction, certain combinations of two extractants under well-defined conditions, results in the extraction of a metal ion species with a significantly enhanced efficiency compared to the additive effect observed when they are used separately. This phenomenon is referred to as Synergism. Carboxylic acids either singly [1-6] or in conjunction with some synergists such as organophosphorus compounds and nitrogen containing bases, have been used for the effective separations of metal ions by the Solvent extraction [7, 8]. Anthranilates of some metals show poor extraction into non-polar solvents like Chloroform and Benzene. However, the addition of neutral donors such as heterocyclic nitrogen containing organic bases to such systems increases the extraction significantly [9]. The present study embodies work on the extraction of Fe (III) in aqueous phase, with anthranilic acid in the presence of pyridine and into benzene. The heterocyclic organic base ligand B is added to the species formed between the metal ion, Mn+ and the anthranilic acid, HA. The synergistic adduct [. ] moves across the aqueous-organic phase boundary into organic phase until an
equilibrium is established such as:
+ + + [. ] + +
According to Distribution Law:
=
Where = Distribution Coefficient, = Concentration of the solute in the organic phase, = Concentration of the solute in the aqueous phase.
If any type of interaction takes place between the extractable species and component in either of the two phases, instead of , the Distribution ratio D is used.
Therefore, = [] = [.] [] [+]
The concentration of Fe(III) in the aqueous phase has been determined spectrophotometrically using Sulphosalicylic acid as the colorimetric reagent and 495 nm as the working wavelength. The concentration of Fe(III) in the organic phase was determined by difference.
The equilibrium constant for extraction is given by:
[. ]. [+]=
[+]. [] . []Hence,
log = log + [] + log [] +
Assuming that the metals do not form any other complex with excess of ligand, the mass balance for base is given by:
[] = [] + [] + [. ] + [+]Hence, is given by,
[] = [] . [. ]+ 1 + [+]
+
Where and + are the partition coefficient and ionization constant of B and +, respectively.
[]and
=
+ =
[] [+]. [] [+]+ and values have been taken from literature [10, 11]. + values for pyridine and are
105.15 and 105.63, respectively. The average values of partition coefficient for pyridine and are
1.95 and 1.85, respectively. The effect of change in variables such as pH of the aqueous phase, metal ion concentration, anthranilic acid concentration, and base concentration, keeping other variables constant, have been studied for each of the two systems (i) Fe (III), anthranilic acid, pyridine, and (ii) Fe(III), anthranilic acid,
by measuring Distribution ratio, D. From the plots log D vs pH, log D vs log [ANTHRA]TOTAL, log D vs log [B]TOTAL, using Slope analysis method, the most probable composition of the synergistic adduct has been postulated as [()2. 2] where B = pyridine or . The equilibrium constant for extraction, of Fe(III) with pyridine and have been calculated as 5.05 and 7.15, respectively. This suggests the effectiveness of pyridine and as synergist in the sequence as:
>
-
MATERIALS AND METHOD
Chemicals used in the investigation were of AR/GR grade. Fe (III) solutions of various concentrations as per requirement, were obtained by dissolving Ferric chloride in doubly distilled water and standardization using EDTA titrations. Anthranilic acid was recrystallised and freshly prepared solutions of anthranilic acid were used throughout the investigations. Standardization of anthranilic acid solution was carried out using acid-base titration.
In each set equal volumes (10 ml) of aqueous phase and benzene were shaken in separating funnel at room temperature (30 ± 2) for 5 minutes to achieve complete equilibration. The aqueous phase contained Fe (III), anthranilic acid, and organic base pyridine or -picoline. The ionic strength of the aqueous phase was maintained constant at 0.1M by adding Sodium perchlorate. The pH of the aqueous phase was adjusted with perchloric acid or sodium hydroxide. After equilibration, the two phases were separated and pH of the aqueous phase was determined. The pH measurements of aqueous phase before and after equilibration were made on an expanded scale pH-meter (ECIL, India). The concentration of Fe(III) in the aqueous phase after equilibration was determined spectrophotometrically by Calibration curve method using BECKMAN DU-6 SPECTROPHOTOMETER, Sulphosalicylic acid as the colorimetric reagent and 495 nm as the working wavelength. The concentration of Fe(III) in the organic phase was determined by difference.
The distribution ratio (D) and the percent extraction (%E) of the metal ion has been calculated as:
=
% =
Analytical Procedure
× 100
In order to investigate the effect of pH of the aqueous phase on the extraction of Fe (III), the extraction studies were carried out at constant metal ion (1.0 × 103), anthranilic acid (0.05M), and pyridine (0.25M) or – picoline (0.5M) concentrations in the pH range 0.5-3.2.
In order to investigate the effect of metal ion concentration on the extraction of Fe (III), the extraction studies were carried out at cnstant anthranilic acid (0.05M) and pyridine (0.25M) or -picoline (0.5M) concentrations and pH of the aqueous phase = 3.2, and varying the Fe (III) concentrations in the range 5.0 × 105
1.0 × 103.
In order to investigate the effect of acid concentration on the extraction of Fe (III), the extraction studies were carried out at constant metal ion (1.0 × 103) and pyridine (0.25M) or -picoline (0.5M) concentrations and pH of the aqueous phase = 3.2, and varying the anthranilic concentration between 0.003-0.035M.
In order to investigate the effect of base concentration on the extraction of Fe(III), the extraction studies were carried out at constant metal ion (1.0 × 103), anthranilic acid (0.025M/0.015M) concentrations and pH of the aqueous phase = 3.2, and varying the pyridine or -picoline concentrations between 0.01-0.25M.
-
RESULTS AND DISCUSSION
-
EFFECT OF pH OF THE AQUEOUS PHASE
The percent extraction of Fe (III) with anthranilic acid is found to increase with pH of the aqueous phase and becomes almost quantitative at pH 3.2, in both the cases of pyridine and -picoline as synergists.
-
EFFECT OF METAL ION CONCENTRATION
The effect of metal ion concentration in the range 5.0 × 105 1.0 × 103M on the extraction of Fe (III) is found to be practically insignificant (±3%). This rule out the possibility of extraction of any polymeric species in the abovementioned concentration range. A concentration of 1.0 × 103M for Fe (III) was chosen to carry out the present investigation.
-
EFFECT OF ACID CONCENTRATION
The experimental data [TABLE-1] of distribution ratio for Fe (III) between aqueous phase and benzene as a function of anthranilic acid concentration at constant Fe (III) concentration, constant pH and constant pyridine concentration (0.25M) or -picoline concentration (0.5M), respectively were obtained. In both cases of pyridine and -picoline as synergists, the extraction of Fe (III) increases with the increase in concentration of anthranilic acid in aqueous phase before equilibration.
TABLE 1. Distribution ratio for Fe (III) between aqueous phase and benzene as a function of anthranilic acid concentration at constant pH and base concentration.
[ANTH]T log [ANTH]T
D
log D
(a)
[Fe]T = 1.0 × 103 , [pyridine]T = 0.25M, pH = 3.2 5.000 × 103
-2.301
6.586
0.819
1.101 × 102
-1.958
12.882
1.109
1.901 × 102
-1.721
19.952
1.299
2.600 × 102
-1.585
27.461
1.439
3.303 × 102
-1.481
35.424
1.549
(b)
[Fe]T = 1.0 × 103 , [-picoline]T = 0.5M, pH = 3.2 3.006 × 103
-2.522
6.046
0.781
6.814 × 103
-2.166
15.342
1.186
8.924 × 103
-2.049
20.657
1.315
1.200 × 102
-1.920
24.618
1.391
1.428 × 102
-1.845
36.054
1.557
1.6
1.5
Slope = 0.9 Pearson's r = 0.99
1.4
1.3
1.2
1.1
1.0
0.9
0.8
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
log [ANTHRA]TOTAL
log D
Plots of log D vs log of total anthranilic acid concentration has been drawn from the extraction data. The plots log vs log[] with pyridine and -picoline give straight line with slope near one. This suggests that in each case of pyridine and -picoline there is utilisation of one acid molecule per metal atom releasing one proton during formation of extracting species [Figure. 1,2].
FIGURE 1: Variation of Distribution ratio for Fe (III) as a function of anthranilic acid concentration at constant pH = 3.2 and at constant pyridine concentration (0.25M)
FIGURE 2: Variation of Distribution ratio for Fe (III) as a function of anthranilic acid concentration at constant pH = 3.2 and at constant -picoline concentration (0.5M)
-
EFFECT OF BASE CONCENTRATION
From the extraction studies, distribution ratio D for Fe (III) between aqueous phase and benzene as function of base concentration at constant pH, total metal ion concentration and acid concentration, has been calculated and reported in [TABLE 2]. The log-log plot of distribution ratio versus base concentration has been drawn at constant pH and acid concentration for each of pyridine and -picoline [Figure 3,4].
TABLE 2. Distribution ratio for Fe (III) between aqueous phase and benzene as a function of base concentration at constant pH and anthranilic acid concentration.
[BASE]T log [BASE]T
D
log D
(a)
[Fe]T = 1.0 × 103 , [anthranilic acid]T = 0.025M, pH = 3.2 5.000 x 102
-1.301
1.000
0.000
7.500 x 102
-1.125
2.636
0.421
1.250 x 101
-0.903
8.749
0.942
1.450 x 101
-0.839
10.116
1.005
1.750 x 101
-0.757
17.179
1.235
2.500 x 101
-0.602
35.399
1.549
(b)
[Fe]T = 1.0 × 103 , [anthranilic acid]T = 0.015M, pH = 3.2 1.000 x 102
-2.000
1.426
-0.154
4.000 x 102
-1.397
6.397
0.806
7.014x 102
-1.154
18.030
1.256
1.000 x 101
-1.000
22.542
1.353
1.300 x 101
-0.886
43.351
1.637
1.6
1.4
1.2
Slope = 2.2 Pearson's r = 0.99
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-1.4 -1.3 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5
log [Pyridine]Total
log D
FIGURE 3: Variation of Distribution ratio for Fe (III) as a function of Pyridine concentration at constant
pH (3.2) and Anthranilic acid concentration (0.025M)
FIGURE 4: Variation of Distribution ratio for Fe (III) as a function of -picoline concentration at constant pH (3.2) and Anthranilic acid concentration (0.015M)
It is observed that with the increase in the concentration of organic bases the extraction of Fe (III) increases. The plot of log D versus log [Base]Total with both the bases gives straight line with slope near two [Figure 3,4]. This suggests the incorporation of two molecules of pyridine or -picoline per metal atom in the extracting species.
-
CALCULATION OF EXTRACTION CONSTANTS (Kex)
Using the equation:
[] = [] . [. ]+ 1 + [+]
+
[B] is calculated. Putting the values of , log [HA], log [B], pH and n = 1, x = 2 in the following equationlog = log + [] + log [] +
Extraction constant, K is computed [TABLE 3, 4].
TABLE 3. Variation of [pyridine] for Fe (III) at constant anthranilic acid concentration (0.025M) and pH = 3.2
[Fe}Total [B] log D
log [B]
log K
Mean of
log K
1.0 × 103M
5.000 x 102
0.000
-3.274
5.00
5.05
7.500 x 102
0.421
-3.097
5.01
1.250 x 101
0.942
-2.874
5.09
1.450 x 101
1.005
-2.808
5.02
1.750 x 101
1.235
-2.726
5.08
2.500 x 101
1.549
-2.569
5.09
TABLE 4. Variation of [ picoline] for Fe (III) at constant anthranilic acid concentration (0.015M) and pH
= 3.2
[Fe}Total [B] log D
log [B]
log K
Mean of
log K
1.0 × 103M
1.000 x 102
-0.154
-4.489
7.75
7.15
4.000 x 102
0.806
-3.851
7.13
7.014x 102
1.256
-3.602
7.08
1.000 x 101
1.353
-3.442
6.86
1.300 x 101
1.637
-3.327
6.92
Computed values of log Kex for pyridine and -picoline are 5.05 and 7.15, respectively. This suggests -picoline as better synergist in comparison to pyridine. This, also, suggests that the stability of the extracting complex of – picoline is higher than those of pyridine.
Plots for log D vs log[B] are drawn using data from TABLE. 3 and TABLE. 4 for pyridine [Figure 5] and – picoline [Figure 6]. The plot gives straight line with a slope nearly two in each case of pyridine and -picoline
1.6
1.4
Slope = 2.19 Pearson's r = 0.99
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-3.3 -3.2 -3.1 -3.0 -2.9 -2.8 -2.7 -2.6 -2.5
log [B]aq
log D
which again suggests incorporation of two base molecules per metal atom during the formation of extracting species.
log D
FIGURE 5: Plot of [] for variation of pyridine concentration at constant Fe (III) concentration, pH, and anthranilic acid concentration
1.8
1.6
1.4
1.2
1.0
Slope = 1.6 Pearson's r = 0.99
0.8
0.6
0.4
0.2
0.0
-0.2
-4.6
-4.4
-4.2
-4.0
-3.8
-3.6
-3.4
-3.2
log [B]aq
FIGURE 6: Plot of [] for variation of -picoline concentration at constant Fe (III) concentration, pH, and anthranilic acid concentration
-
EXTRACTED SPECIES
On the basis of the extraction data, assuming coordination number of Fe (III) to be six the representation of extracting species may be proposed as
().
-
-
CONCLUSION
The reported extracting species in the present investigation is [(). ]
which contains hydroxyl group in the coordination sphere of the metal ion. Considering the pH of aqueous phase, it is expected. Comparing the value of extraction constant (Kex), the effectiveness of pyridine and -picoline as synergist is in the sequence as
>
-
ACKNOWLEDGEMENT
The author is grateful to the Department of Chemistry, Indian Institute of Technology, Roorkee for providing research facilities to complete this work.
-
CONFLICT OF INTEREST
The author declares that there is no conflict of interest.
-
REFERENCES
-
F. Miller, Carboxylic acids as metal extractants, Talanta, 1974, 21(7), 685 703.
-
N. M. Rice, Recent developments and potential uses for carboxylic acid extractantsA review, Hydrometallurgy, 1978, 3(2), 111 133.
-
J.S. Preston, Solvent extraction of metals by carboxylic acids, Hydrometallurgy, 1985, 14(2), 171 188.
-
Hiromichi Yamada; Motoharu Tanaka, Solvent Extraction of Metal Carboxylates, Advances in Inorganic Chemistry, 1985, 29, 143 168.
-
Isao Kojima; Masao Uchida; Motoharu Tanaka, Extraction of copper (II) with aliphatic carboxylic acids, Journal of Inorganic and Nuclear Chemistry, 1970, 32 (4), 1333 1340.
-
J.M. Singh; S.K. Gogia; S.N. Tandon, Study of the extraction of zinc (II), cadmium (II) and mercury (II) with caprylic acid, Hydrometallurgy, 1982, 9 (1), 97-102.
-
Kyu Sun Bai, Equilibrium studies of U(VI) extraction with anthranilic acid and tri-n-butyl phosphate, Journal of Inorganic and Nuclear Chemistry, 1981, 43 (10), 2525 2528.
-
J.M. Singh; Bina Gupta; S.N. Tandon, Studies on the extraction of Mn (II) with anthranilic acid in the presence of -picoline, pyridine and quinoline, Journal of Inorganic and Nuclear Chemistry, 1981, 43 (8), 1863-1865.
-
Bina Jain; J. M. Singh; R. N. Goyal, S. N. Tandon, Extraction of Zn(I1) and Cd(I1) with anthranilic acid in the presence of nitrogen-containing organic bases, Can. J. Chem., 1980, 58, 1558 1561.
-
R. J. L. Andon; J. D. Cox; E. F. G. Herington, The Ultra-Violet Absorption Spectra and Dissociation Constants of Certain Pyridine Bases in Aqueous Solution, Trans. Faraday Soc., 1954, 50, 918.
-
J. M. Singh; S. N. Tandon, Extraction of cadmium salicylate with some nitrogen-containing organic bases, Canadian Journal of Chemistry, 1978, 56 (23), 2922 2926.
