Characterization of 5-nonylsalicylaldoxime production and the effects of modifiers on its extracting/stripping properties

Article abstract of DOI:10.1007/s11164-012-0556-3

The 5-nonylsalicylaldoxime or 2-hydroxy-5-nonylbenzaldoxime namely aldoxime is a strong copper extractor that is mainly used in the process of copper solvent extractions. In order to characterize the aldoxime production process and to obtain a pure substance for using in the subsequent investigations, this reagent was synthesized and instrumental analysis such as FT-IR, ¹H-NMR, and GC/MS spectra were first taken on the final product. The effects of various modifying reagents were studied on the synthesized aldoxime for improving its extracting and striping properties in the Cu (II) extraction processes. An optimum formulation of organic phase including the aldoxime and some modifier reagents was determined based on the variation of type and the concentration of the modifiers. The obtained experimental data show that the net copper transferring in a mixture of the aldoxime and modifier mainly the aliphatic alcohols (C₁₂ (40 % w/w) and C₁₄ (60 % w/w)) is greater than the aldoxime alone and greater than its other mixture. Springer Science+Business Media B.V. 2012.

Full text of DOI:10.1007/s11164-012-0556-3

Res Chem Intermed (2012) 38:2401–2409
DOI 10.1007/s11164-012-0556-3
Characterization of 5-nonylsalicylaldoxime production
and the effects of modifiers on its extracting/stripping
properties
Zeinab Pouramini Ali Moradi
•
Received: 13 March 2012 / Accepted: 3 April 2012 / Published online: 29 April 2012
Ó Springer Science+Business Media B.V. 2012
Abstract The 5-nonylsalicylaldoxime or 2-hydroxy-5-nonylbenzaldoxime namely
aldoxime is a strong copper extractor that is mainly used in the process of copper
solvent extractions. In order to characterize the aldoxime production process and to
obtain a pure substance for using in the subsequent investigations, this reagent was
1
synthesized and instrumental analysis such as FT-IR, H-NMR, and GC/MS spectra
were first taken on the final product. The effects of various modifying reagents were
studied on the synthesized aldoxime for improving its extracting and striping
properties in the Cu (II) extraction processes. An optimum formulation of organic
phase including the aldoxime and some modifier reagents was determined based
on the variation of type and the concentration of the modifiers. The obtained
experimental data show that the net copper transferring in a mixture of the aldoxime
and modifier mainly the aliphatic alcohols (C12 (40 % w/w) and C14 (60 % w/w)) is
greater than the aldoxime alone and greater than its other mixture.
Keywords Copper Á Solvent extraction Á Nonylsalicylaldoxime Á Modifier Á
Net transfer
Introduction
Aromatic hydroxyoximes, which are mainly used as the extracting reagents of
copper (II), are divided into two classes of the 2-hydroxy nonyl aceto phenoxime
(briefly ketoximes) and the 2-hydroxy-5-nonylbenzaldoxime (briefly salicylaldox-
imes) [1–3].
Z. Pouramini Á A. Moradi (&)
Department of Chemical Engineering, Engineering Faculty, Jomhouri Islami Blvd.,
Shahid Bahonar University of Kerman, PO Box 76175-133, Kerman, Iran
e-mail: moradi@mail.uk.ac.ir; alimoradi2006@yahoo.com
123

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Z. Pouramini, A. Moradi
The salicylaldoximes, which are much stronger extractants than the ketoximes,
have considerable advantages, such as rapid copper transfer kinetics, excellent
copper selectivity versus other metallic ions, mainly iron, and fast phase separation
due to bearing a long alkyl tail [3–8].
Different methods for the preparation of hydroxyl benzaldehyde and its
derivatives were reported in the articles [9–13]. Phenolic aldehydes have so far
been synthesized according to the well-known Reimer–Tiemann reaction in which
phenol is reacted with chloroform in the presence of a powerful basis such as
potassium hydroxide. This process, besides having the difficulty of handling with
chloroform, has some significant problems such as low yield of reaction,
unselectively, and the necessity of a large amount of chloroform consumption
[
14, 15].
A modified Duff reaction was reported by Lindoy et al. [16]. Its main
disadvantage is the lack of regioselectivity, i.e., in the formylation process,
substitution can occur in both the ortho and para positions to the phenol and hence
diformylated products are common [17].
Casiraghi et al. [18] reported that the reaction of paraformaldehyde and
magnesium phenoxide, produced from alkyl phenol and ethylmagnesium bromide in
benzene as solvent in the presence of stoichiometric amount of hexamethylphos-
phoric triamide (HMPTA), resulted in formylation exclusively at the ortho position.
An improved method in the absence of HMPTA has been reported [19]. The ortho-
formylation was successfully carried out by paraformaldehyde and magnesium bis
(phenoxides), which are prepared from phenols and magnesium methoxide in
methanol as the cosolvent instead of HMPTA by Levin [20].
The Levin method, which involves magnesium mediated ortho-formylation is
usually chosen when selective mono-formylation is desired and more than one site
for incorporation of the -HC=O group is possible [17].
Although salicyladoxime is a stronger extractant, its striping behavior is weak. In
fact, salicylaldoxime makes such strong bonds with metal (or copper) ions that it
could hardly be separated in its stripping step. Therefore, it is a common
hydrometallurgical and well-known practice to add some modifiers to the extraction
systems to improve its stripping and/or extracting behaviors. These compounds (by
making a hydrogenic connection with metal ions and hence by creating a steric
hindrance around it) cause ease of separation of these ions from the salicyladoxime
reagent. These modifiers also provide a net copper transfer greater than that
achieved in the absence of a modifier. Modification properties are shown by such
compounds as: long chain alcohols, ethers, esters, or other extractants (i.e.,
tridecanol, isodecanol, methylpentandiol, nonyl phenol, 2-2-4 trimethyl-1-(2-
methylpropanoyl) or TXIB) [3, 21–25].
The modifier/extractant ratio is an important parameter that effects the
composition of the organic phase. The high modifier/extractant ratio increases the
viscosity and density of the organic phase. Both of these properties cause a poor
phase separation and/or crud generation in the mixer/settler. The molar ratios of the
modifier to extractant could be varied from about 0.05 to about 2.0 [26–28].
The industrial extractants, which are manufactured by different companies,
always have trade names such as LIX 860, LIX 984N Acorga 5640M, 5650, and so
1
23

Characterization of 5-nonylsalicylaldoxime production
2403
on. They may not have a well-known composition, and therefore the amounts of
their modifier and their diluents are not distinguishable [1, 3, 24–28].
The modification of salicylaldoxime is an issue that has been less asserted in
the articles. Therefore, the main purpose of this research is to study and
characterize the ortho-formylation of nonylphenol to nonylsalicylaldehyde by
direct reaction of solid paraformaldehyde on magnesium phenoxide and its
oximation to the nonylsalicylaldoxime firstly. Secondly, the modification of
salicylaldoxime would be studied by an effective modifier such as nonyphenol,
tridecanol, or ketoxime.
Materials and methods
Materials
Commercial grades of nonylphenol (with the melting point of -2 to -8 °C and the
boiling point of 293–297 °C) and magnesium powder (with the melting point of
6
50 °C) were prepared from Merck Chemical Company and used. Commercial-
grade paraformaldehyde (with a boiling point of 120–170 °C) was applied.
Industrial-grade toluene and methanol were prepared from Isfahan, Iranian,
petrochemical companies and used after twice distillation (the boiling point of
toluene and methanol after purification were about of 110.5, 64.7 °C respectively).
Industrial-grade aliphatic alcohols (C (40 % w/w) and C (60 % w/w)) and p-
1
2
14
nonylphenol and kerosene were applied.
Commercial-grade kerosene was used as organic solvent with the following
3
specifications: flash point of 106 °F, density (15 °C) of 0.808 g/cm , viscosity
(
sulfate, and H SO were prepared from Merck Chemical Company.
20 °C) of 2.19 centistoke were purchased and used. Copper (II) sulfate, Iron (III)
2
4
Industrial-grade aliphatic alcohols (a mixture of C12 (40 % w/w) and C14 (60 %
w/w)) and p-nonylphenol and the synthesized ketoxime (2-hydroxy-5-nonyl
acetophenone oxime), which was prepared by these authors, were used as modifier
[
29].
Equipment
A 3-l round-bottom, four-necked flask equipped with a mechanical mixture and a
condenser were used. An electrical heater was applied for heating.
A Fourier transfer infrared (FTIR) spectrophotometer (Bomem model MB100)
and a nuclear magnetic resonance (NMR) spectrometer (Bruker Avance Drx-500)
were used. GC/MS data were recorded on an Agilent 6890 series GC system and
Agilent 5973 network MSD using a 30-m HP-1MS column, 0.25-mm inner
diameter, and program temperature 50–275 °C (15 °C/min).
Atomic absorption spectrometry (Varian 220 AA) was used to determine the
amount of metallic ions, especially copper and iron.
123

2404
Z. Pouramini, A. Moradi
Methodology
Twelve grams of magnesium powder in methanol (405 g) reacted at reflux
temperature (63 °C) for up to 15 h. When the color of the mixture became milky
and all the magnesium was dissolved, nonylphenol (220 g) was added to the
solution of magnesium methoxide in methanol. The mixture was refluxed for 3 h.
When, more than half of the methanol was distilled off, toluene (400 g) was added
to the residue in two steps. The rest of the toluene (up to 100 g) was added at about
the end of distillation. When the temperature of reaction mixture reached about
9
5 °C, paraformaldehyde (75 g) was added over 4 h with countercurrent removal of
volatile materials by distillation. Stirring was continued at 95–100 °C for 3 h, and
then the mixture was cooled to 45 °C and treated with a solution of hydroxylamine
hydrochloride (69 g, 1 mol) in water (300 g) over 1 h at 45–50 °C with vigorous
stirring. Stirring was continued at 50 °C for 4 h. The layers were separated. The
aqueous layer was extracted with toluene (100 g). The organic layers were
combined and washed with 7 % sulfuric acid (270 g) and water (250 g). The solvent
was removed under reduced pressure to yield a viscous, pale yellow liquid oxime,
which was 5-nonylsalicylaldoxime. Figure 1 shows the mechanism of these
reactions consequently.
Production of copper solvent extraction mixture
Modifier solutions including a mixture of aliphatic alcohols including C12 (40 % w/w)
and C14 (60 % w/w), p-nonylphenol and synthesized ketoxime were prepared at the
molarity of 0.025, 0.1, and 0.2 by weighing the appropriate amount of modifiers into a
1
00-ml volumetric flask. It was then added to the 25 ml of 25 w/v % of aldoxime in a
volumetric flask and it was diluted to 100 ml via kerosene. The molarity of aldoxime
would be 0.23. Kerosene (or in some cases toluene) was used to dilute the organic
OH
O
O
Mg(OMe)2
MeOH
Mg
2
R
R
R
Paraformaldehyde
Toluene
OHC
Mg
R
NOH
OH
R
O
(
NH OH) SO
3 2 4
O
2
R
CHO
R=C H
9
19
Fig. 1 The reactions of 5-nonylsalicylaldoxime production
1
23

Characterization of 5-nonylsalicylaldoxime production
2405
extractant. Stripping solution was prepared by diluting a measured amount of the
2
copper (II) sulfate (30 g/l Cu ) and H SO (150 g/l) into distilled water.
?
2
4
The synthetic aqueous solutions of desired composition were prepared by
dissolving copper (II) sulfate (CuSO Á5H O) and iron (III) sulfate (Fe (SO ) ÁxH O)
4
2
2
4 3
2
(
reagent grade, from Merck) in distilled water.
Equilibrium experiments were carried out by the following procedure. Equal
volumes of aqueous and organic phases were contacted by vigorous mixing in a 1-l
vessel equipped with a mechanical mixer for 20 min at room temperature. The two
phases were separated and the copper content of aqueous phase was determined by
atomic absorption spectrometry. The metal concentration in the organic phase was
calculated via mass balance.
For determination of strip point of organic phase, it was contacted three times
with stripping solution. The two phases were separated, and then the copper content
of stripped organic phase was determined after transferring it to the aqueous
medium. Ten milliliters of the organic phase was poured into a separating funnel.
The metals were extracted by shaking for 1 min with three separate 20-ml portions
of 15 % (v/v) sulfuric acid. After combining the acid washes, the copper amounts
were determined by atomic absorption spectrometry. In both the extraction and
stripping process, the aqueous/organic volume ratio was 1:1. The experiments were
carried out similar to the standard quality control tests [30, 31].
Results and discussion
The 1H-NMR, FT-IR, and GC/MS spectra of nonylsalicylaldoxime were taken and
they are interpreted in this section.
H-NMR spectrum
1
The H-NMR spectrum of nonylsalicylaldoxime was taken. The peaks of nonyl
(
C H ) were shown at d 0.8–1.7. The sharp peak of methyl protons of toluene
9
19
appeared at 2.4 ppm. The multiple peaks around d 6.9–7.33 could be assigned to the
aromatic protons. The sharp peak of CH=N was observed at d 8.3, that is to say, the
oxime group in final product have been formed. The sharp singlet of the oxime
hydroxyl group was seen at d 9.95. This peak shows the development of oximation
reaction. Lack of aldehyde peaks reveals that any aldehyde groups have not
remained and approximately all of them were oximated. The signals of phenolic
hydroxyl protons appeared at d 10.8 and d 11. These peaks show that the
unoximated has been removed and the oximation reaction has not been completed.
GC/MS spectrum
GC/MS chromatogram was used for detection of nonylsalicylaldoxime by
Mw = 263. The peak at 26.48 min that having m/z 281.1 could be assigned to
the nonylsalicylaldoxime. This spectra emphasize on the formation of final product,
123

2406
Z. Pouramini, A. Moradi
reasonably. The appearance of other peaks is due to using from the industrial grades
of materials, especially nonylphenol.
The FT-IR spectrum
The FT-IR spectrum for the nonylsalicyaldoxime was taken. This spectra shows an
-
1
OH stretching vibration in the 2,900–3,500 cm region, which should be due to
phenolic and oxime hydroxyl and also due to the C–H band in nonyl and oxime. The
-
band at 1,623 cm should be due to C=N band of the oxime group. The vibration
1
-
1
band that appeared at 1,585 cm could be assigned to the C=C band in the
aromatic ring.
The extraction behavior of salicyladoxime alone
The effect of aqueous pH on its extraction
Figure 2 shows the effect of pH of the aqueous solution having 5 g/l copper
concentration. The organic phase of this experiment involves the synthesized
aldoxime without any modifier diluted in toluene.
The organic phase containing aldoxime solution was loaded after three times
contacting with fresh aqueous solution. It can be seen that maximum copper
extraction could be obtained at initial aqueous pH, i.e., about 1.7–2.5 range.
The effect of concentration on solvent extraction of copper by synthesized aldoxime
In these experiments, the aqueous solutions were prepared in concentration of 6 g/l
2
?
3?
Cu and 3 g/l Fe and at the pH of 1.9. Extraction at higher pH due to the risk of
extraction of other ions, especially iron, is not recommended and lowering the pH
than that shall decrease the amount of extraction.
The organic phase comprises of the synthesized aldoxime that was diluted in
kerosen. The results of extraction/stripping for the synthesized aldoxime are as
follow; Extraction isotherm point, Stripping isotherm point, Loading percentage,
Stripping Percentage, Net Copper Transfer and Maximum loading (g/l Cu) are 4.48,
4
.48, 74.6, 43, 1.94, 4.5 respectively. These results show that the extraction ability of
Fig. 2 Effect of aqueous pH on
copper extraction
1
23

Characterization of 5-nonylsalicylaldoxime production
2407
this regent is good but its stripping ability is weak; therefore some modifiers have to
be added to the organic phase to improve the stripping ability and net copper transfer.
In this work, also 80 % of loaded copper plus its accompanied aldoxime in organic
phase was stripped via contacting the same volume aqueous solution, which has
1
50 g/l H SO with organic phase (the stripping solution did not include copper).
2 4
Results of the mixture of salicylaldoxime and modifiers
The effect of type and concentration of modifiers on the extraction-stripping process
Table 1 shows the results of the extraction-stripping testes for modified aldoxime.
The molarity of aldoxime in all experiments was 0.23, so the molar ratio of modifier
to aldoxime would be about 0.05–1. The concentration of Cu in aqueous phase was
6
g/l.
Figure 3 shows the percentage of copper extraction versus modifiers
concentration.
Figure 4 shows the effect of modifiers concentration on the stripping process.
Table 1 Result of the extraction-stripping testes for the modified aldoxime
Modifier type
Molarities
of modifier
Loaded organic
(g/l Cu)
Stripped organic
(g/l Cu)
Net copper transfer
(g/l Cu)*
Aliphatic alcohol
0.025
4.26
3.92
3.58
4.36
4.30
3.88
4.49
4.8
1.61
1.14
0.69
1.87
1.67
1.35
2.07
2.21
2.49
2.65
2.78
2.88
2.49
2.63
2.53
2.42
2.59
2.67
0
0
.1
.2
p-Nonylphenol
0.025
0
0
.1
.2
Synthesized ketoxime
0.025
0
0
.1
.2
5.16
*Net transfer equals subtraction of Cu concentration (g/l) of stripped organic from Cu concentration (g/l)
of loaded organic
Fig. 3 Effect of modifier concentration on extraction of copper
123

2408
Z. Pouramini, A. Moradi
Fig. 4 Effect of modifier concentration on stripping of copper
As shown in Table 1 and illustrated in Figs. 3 and 4, by increasing the
concentration of modifier, the extracting values of aldoxime modified by aliphatic
alcohols and p-nonylphenol have decreased but the stripping values of both of them
have increased compared with aldoxime alone. Also, it can be seen from Table 1
that net copper transfer increased by increasing the concentration of modifiers. In
addition, the net copper transfer became greater than that achieved by the extraction
of aldoxime alone.
Furthermore, as shown in Figs. 3 and 4, the aldoxime/ketoxime mixture shows an
extraction and stripping behavior better than that achieved by aldoxime alone,
because this mixture includes the ability of aldoxime and ketoxime simultaneously.
Results have shown that the maximum net copper transfer is 2.88 g/l Cu when
the modifier is a mixture of aliphatic alcohols (C12 (40 % w/w) and C14 (60 %
w/w)) in the molarity of 0.2.
By increasing the bond of modifiers to the copper ion and increasing of streak
hindrance the amount of aldoximes that have linked to the copper ion will be
decreased eventually. Therefore the extracting ability of mixture will decrease but
the stripping ability of mixture will increase at low pH. Besides, the penetration of
modifier to the adsorption layer decreases the interfacial concentration of hydrox-
yoxime molecules at the interface and the rate of the metal extraction decreases.
Aliphatic alcohols show a greater electron density around their oxygen atom than
alkylphenols, and they associate with hydroxime molecules more easily. The
amount of alcohol for obtaining a definite modification in extraction result is lower
than the nonylphenol one.
Conclusions
The results of the reaction step for the synthesizing of salicyladoxime show that the
orthoformylation and othoselectivity for this technique is practically high and
the amounts of by product are fairly low. The results of extraction show that the
synthesized 5-nonylsalicylaldoxime has basically good performance but its stripping
1
23

Characterization of 5-nonylsalicylaldoxime production
2409
power is low. All of the applied modifiers show an improvement in the stripping
capacity and as a result, the overall net transfer of copper was increased. Although
the alkyl alcohol lowers the ability of extracting but due to the increasing of
stripping ability and as a result due to the increasing of net transfer amount, it is
concluded that using a high concentration of alkyl alcohol could be preferred than
ketoxime.
References
1
2
3
4
5
6
. A.J. Monhemius, Bull. Chem. Maced. 13, 7 (1994)
. A. Ocio, M. Elizalde, J.A. Prieto, J. Chromatogr. A 1032, 129 (2004)
. MCT_Redbook, Solvent Extraction Reagents and Applications (Cognis Corporation, USA, 2007)
. M.B. Bogacki, J. Szymanowski, Ind. Eng. Chem. Res. 29, 601 (1990)
. P. Navarro, F.J. Alguacil, Miner. Eng. s12, 323 (1999)
. L. Qing-ming, Y. Run-lan, Q. Guan-zhou, F. Zheng, C. Ai-liang, Z. Zhong-wei, Trans. Nonferrous
Met. Soc. China 18, 1258 (2008)
7. K.S. Rao, N.B. Devi, B.R. Reddy, Hydrometallurgy 57, 269 (2000)
8. K. Yoshizuka, H. Arita, Y. Baba, K. Inoue, Hydrometallurgy 23, 247 (1990)
9. J.H. Dimmite, M.A. Kearns, W.H. Chambless, US Patent 6288276 (2001)
1
1
1
1
1
1
1
1
1
0. T. Matsuda, T. Murata, US Patent 4231967 (1980)
1. M. Virnig, US Patent 4638096 (1987)
2. G.E. Beswick, US Patent 4085146 (1978)
3. S.B. Paliwal, V.B. Mathur, B.N. Mirani, WO 2007/034501 (2007)
4. A. Thoer, G. Denis, M. Delmas, A. Gaset, US Patent 4755613 (1988)
5. H. Wynberg, E.W. Meijer, W.G. Dauben, (John Wiley and Sons Inc., New York, 1982), pp 1–36
6. L.F. Lindoy, G.V. Meehan, N. Svenstrup, Synthesis. 1029 (1998)
7. R.S. Forgan, PhD Thesis. University of Edinburgh (2008)
8. G. Casiraghi, G. Casnati, M. Cornia, A. Pochini, G. Puglia, G. Sartori, R. Ungaro, J. Chem. Soc.
Perkin Trans. 1. 318 (1978)
1
2
2
2
2
2
2
2
2
9. N.U. Hofsløkken, L. Skattebøll, Acta Chemica Scandinavica. 258 (1999)
0. R. Aldred, R. Johnston, D. Levin, J. Neilan, J. Chem. Soc. Perkin Trans. 1. 1823 (1994)
1. A.D. Sugarman, US Patent 6726887 (2004)
2. M.B. Bogacki, Ind. Eng. Chem. Res. 38, 1611 (1999)
3. K. Staszak, K. Prochaska, Hydrometallurgy 90, 75 (2008)
4. C. Maes, T. Moore, O. Tinkler, R. Swart, J Miner Met Mater Soc. 31 (2003)
5. F.J. Alguacil, A. Cobo, M. Alonso, Chem. Eng. J. 85, 259 (2002)
6. A. Ocio, B. Menoyo, M. Elizalde, Can. J. Anal. Sci. Spectrosc. 54, 63 (2009)
7. T.A. Ainscow, I. Aldalur, A.E. Beezer, J.A. Connor, N.C. Garbett, J.C. Mitchell, A.L. Page,
N. Tindale, K.A. Turner, R.J. Willson, J. Colloid Interface Sci. 213, 87 (1999)
8. S. Nishihama, T. Hirai, I. Komasawa, Ind. Eng. Chem. Res. 40, 3085 (2001)
9. A. Moradi, R. Atashdehghan, Sh. Daneshpazhooh, 12th Congress of Chemical Engineering, Tabriz,
Iran, October 12 (2008)
2
2
Ò
30. Acorga Extraction Reagents: Standard Test Methods, Technology Note (2005) www.cytec.com
31. M.J. Virnig, P.L. Mattison, L.O. Krbechek, J.M. Macenzie, US Patent 6231784 B1 (2001)
123