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INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)
ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue V, May 2026
Extraction of Fe (III) Salicylates using Tris (2-Ethyl hexyl) Phosphate.
Astha Singh, Sumit Jaiswal & Supriya Deshmukh*
Department of Chemistry Jai Hind College Churchgate, Mumbai-400020.
DOI:
https://doi.org/10.51583/IJLTEMAS.2026.150500127
Received: 29 April 2026; Accepted: 04 May 2026; Published: 08 June 2026
ABSTRACT
Iron is one of the most essential elements for life, playing a crucial role in both biological systems and industrial
development.
From a biological perspective, iron is vital for the formation of haemoglobin, which is responsible for
transporting oxygen in our body. Without adequate iron, the body cannot produce enough healthy red blood cells,
leading to conditions such as Iron Deficiency Anaemia.
From an industrial point of view iron is the backbone of modern civilization. It is the primary component of
steel, which is used extensively in construction, transportation, machinery, and infrastructure. From buildings
and bridges to automobiles etc.
The Solvent extraction of Fe (III) from hydrochloric acid can be accomplished with various neutral
organophosphorus compounds such as TBP, TOPO and other oxygen containing solvents such as alcohols, esters,
ketones, dichloroether.
The paper describes the extractive determination of iron using sodium salicylate with TEHP as the extractant.
Iron Fe³⁺ is a hard Lewis acid (high charge density) and TEHP has a phosphoryl oxygen (P=O) that acts as a
strong donor ligand. The bulky 2-ethylhexyl groups in TEHP increase electron donation to the P=O group,
enhancing its complexation ability with Fe³⁺. Compared to other organophosphorus extractants such as tributyl
phosphate (TBP) and acidic extractants (e.g., D2EHPA), TEHP exhibits higher extraction efficiency and
selectivity toward Fe³⁺, particularly under moderate acid conditions. Its enhanced hydrophobicity and branched
structure contribute to improved phase separation, reduced third-phase formation, and higher metal loading
capacity. These properties make TEHP more suitable for the present extraction system.
Experimental Procedure
The stock solution of Fe (III) was prepared by dissolving 4.3 g of ferric ammonium sulphate in 5 cm
3
of sulphuric
acid followed by heating and diluting to 100 cm
3
with distilled water. The solution was standardized by known
method and test solutions of lower concentrations were prepared by appropriate dilution of stock solution.
Potassium thiocyanate (20%) is used for colour development and absorbance is measured using a
spectrophotometer.
To an aliquot (25 cm
3
) of solution containing 70 μg of Fe (III) and 0.008-0.009 M sodium salicylate was adjusted
to pH 3.0-3.3 and equilibrated for 45 sec with 5 cm
3
of 18% tris(2-ethylhexyl) phosphate in toluene. After
stripping with two 5cm
3
portions of water the metal ions were determined spectrophotometrically using 20%
potassium thiocyanate at 480 nm against the reagent blank.
RESULTS AND DISCUSSION
The variation in concentration of TEHP (10% -20%), pH (1.8-4.0) and concentration of sodium salicylate
(0.0007-0.01M) on the extraction of Fe (III) was studied.
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INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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Effect of Diluents
The suitability of diluents was studied using solvents such as benzene, chloroform, cyclohexane, toluene, xylene
and carbon tetrachloride. TEHP dissolved in xylene or toluene gave the best results.
Period of Equilibration
Variation in shaking period between 10 sec to 100 sec showed that 45 sec equilibration period was adequate for
quantitative extraction of Fe (III). Shaking for more time led to formation of emulsion.
Nature of Extracted Species
The probable extracted species was ascertained from the log-log plots of distribution ratio versus salicylate
concentration (at fixed pH and TEHP concentration) gave a slope of 1.9. The logarithmic plot of D vs log TEHP
concentration (at fixed pH and sodium salicylate concentration) gave a slope of 4. This indicates the formation
of an ion-pair Msal
+
Hsal
-
.4TEHP, where M is Fe (III).
Log D against log TEHP
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INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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Effect of Diverse ions
Varying amounts of foreign ions were added to a fixed amount of iron (70 μg) to study their interference in the
recommended procedure. The tolerance limit was set at the amount required to cause +_ 2% error in iron
recovery.
There was no interference from 2000 μg each of Ni (II), nitrite and nitrate,1000μg each of Pb (II), Mn (II) and
ascorbate,1500 μg each of Cu (II)and citrate,1000 μg of Zn (II),500 μg of Co (II).
Binary Separation of iron (III) from Nickel (III), Copper (II), Cobalt (II) and Zinc (II).
The extraction of iron (III) by the recommended procedure facilitates its separation from nickel (II), Copper (II),
Zinc (II)and Cobalt (II) as these metal ions do not extract into the TEHP phase and remain completely in the
aqueous phase.
Nickel (II), Copper (II), Zinc (II) were determined spectrophotometrically with 4-(2-pyridyl azo) resorcinol
(PAR)
4
, 1-(2-pyridyl azo) naphthol (PAN)
5,6
respectively.
Iron (III) from the organic phase was stripped with two 5 cm
3
portions of water and subsequently determined
spectrophotometrically using potassium thiocyanate at 480 nm.
Analysis of Fe (III) in Pharmaceutical Sample.
A tablet of Supradyn was dissolved in 4 cm
3
of aqua-regia, and the solution was evaporated to dryness. The
residue was taken in water, filtered and diluted to 250 cm
3
. A 1.5 cm
3
aliquot of the solution was analysed for
the iron content. 99.2% iron was extracted by the proposed method.
CONCLUSION
The present study demonstrates that tri(2-ethylhexyl) phosphate (TEHP) dissolved in toluene is an effective
extractant for the solvent extraction of Fe³⁺ from sodium salicylate medium. The extraction process proceeds
efficiently via the formation of a solvated Fe(III)–salicylate complex with TEHP, indicating a neutral solvation
mechanism.
High extraction efficiency was achieved under optimized conditions, highlighting the strong affinity of TEHP
toward Fe³⁺ in the presence of salicylate ions. The distribution behavior suggests that the extraction is dependent
on parameters such as extractant concentration, aqueous phase composition, and pH, confirming the role of
complex formation in the organic phase.
The use of toluene as diluent provided good phase separation, minimized emulsion formation, and ensured
stability of the extracted species. Compared to commonly used organophosphorus extractants, TEHP exhibited
favourable extraction characteristics, including improved selectivity and loading capacity for Fe³⁺ under the
studied conditions.
Overall, the TEHP–toluene system proves to be a simple, efficient, and reliable method for the separation and
recovery of Fe³⁺ from salicylate media, with potential applicability in analytical separations.
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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue V, May 2026
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