Solvent Extraction Research and Development, Japan, Vol. 16, 47-56 (2009)

A Novel Extractant Based on D-Glucosamine for the Extraction of
Molybdenum and Tungsten
Takahide NAKAMURA, Syouhei NISHIHAMA, and Kazuharu YOSHIZUKA*
Department of Chemical Engineering, The University of Kitakyushu,
Hibikino 1-1, Kitakyushu 808-0135, Japan(Received December 25, 2008; Accepted February 3, 2009)
A novel D-glucosamine based extractant, 2-deoxy-2-aminio-1,3,4,6-tetra-O-decanoylD-glucopyranose, has been synthesized and employed for the extraction of Mo(VI) andW(VI) in chloride, nitrate, and sulphate media using a mixture of toluene and 1-octanol as
the diluent. At low pH, W(VI) is selectively extracted, while Mo(VI) is poorly extractedwith this extractant. Little extraction of both metals takes place at high pH. The extraction isaffected by the coexisting inorganic anions, Cl-, NO3-, and SO42-. The selectivity for W(VI)against Mo(VI) is the result of steric hindrance caused by the bulky alkyl chain covered theamine ligand site, compared with commercial amine type extractants, TOA and Primene
JM-T.

1. Introduction
A large number of extractants have been developed from the viewpoint of separation of metal values
and/or removal of toxic metals from waste water. Extractants based on biomolecules, such as chitosan andchitin have become quite attractive in recent years, and the extractants have been demonstrated to haveunique behaviors in metal extraction [1], though there are few reports of biomolecule-based extractants formetals extraction. One of the biomolecules, having the potential as the framework for an extractant, isD-glucosamine which is shown in Fig. 1. D-Glucosamine is a type of amino sugar, and is widely used inhealth foods while the monomer unit of chitosan has an anion-exchangeable primary amino group. In
addition, D-glucosamine can be easily lipophilized by introducing long-chain alkyl groups to its hydroxyl
groups and a D-Glucosamine-based extractant consisting of carbon, hydrogen, oxygen, and nitrogen atoms
would be completely combustible.
Anion exchange extractants have generally high extractability for anionic metal complexes, such as- 47 -

molybdenum, tungsten, and vanadium. Many studies of the anion exchange extraction of these metals havebeen conducted with Primene JM-T (primary amine) [2], diisododecylamineOH(DIDA, secondary amine) [3], Alamine336 (tertiary amine) [4], andO

TOMAC (quaternary ammonium salt) [5].

OH

OH

In the present work, a novel extractant, 2-deoxy-2-aminio-1,

OH

3,4,6-tetra-O-decanoy-D-glucopyranose (C9GLN), has been synthesized

NH2

from D-glucosamine as the extractant for the anionic forms of Mo(VI) and

Fig.1 Chemical structure ofW(VI). The extraction behavior of these metals was investigated in

D-glucosamine.

conventional batch extraction tests. The effect of the aqueous media on theextraction behavior of Mo(VI) and W(VI) was also investigated. The extraction and separation ability ofthe extractant is compared with commercial amine type extractant, and the potential of the new extractant is
discussed.

2. Experimental
2.1 Materials
D-Glucosamine hydrochloride, n-decanoic anhydride, and 4-dimethylaminopyridine were suppliedby Tokyo Chemical Industry Co., Ltd. Pyridine, p-anisaldehyde, all inorganic reagents, and organic
solvents were supplied by Wako Pure Chemical Industries. Commercial extractants, tri-n-octylamine(TOA) and Primene JM-T (mixture of highly branched C16 to C22 tertiary alkyl primary amine isomers)
were supplied by Wako Pure Chemical Industries and Rohm and Hass Company, respectively. These
extractants were used without further purification.
2.2 Synthesis of the extractant
The extractant was synthesized according to the procedures reported by Silva et al., as shown in
Scheme 1 [6].
2-p-Methoxybenzylideneamino-D-glucosamine (1)D-Glucosamine hydrochloride (20.0 g, 92.8 mmol) was dissolved in 100 mL of 1 mol/L sodiumhydroxide solution, and p-methoxybenzaldehyde (13.1 g, 95.9 mmol, 1.0 eq.) was slowly added to thesolution in an ice bath under a nitrogen atmosphere. The mixture was stirred vigorously for 12 h. The
resulting white solid was collected by filtration, and then was washed with deionized water and mixture ofmethanol and diethyl ether. The white solid was dried in vacuo overnight (19.5 g, 70.5 % yield). The
product was identified by 1H-NMR spectrometry (JEOL, JMM-ECP500). 1H-NMR (500 MHz, DMSO-d6)
δ 8.11 (s, 1H), 7.68 (d, J = 8.2 Hz, 2H), 6.99 (d, J = 8.7 Hz, 2H), 6.52 (d, J = 6.9 Hz, 1H), 4.92 (d, J = 5.0
Hz, 1H), 4.81 (d, J = 6.0 Hz, 1H), 4.69 (t, J = 7.1 Hz, 1H), 4.54 (t, J = 6.0 Hz, 1H), 3.80 (s, 3H), 3.72 (m,1H), 3.44 (m, 1H), 3.24–3.14 (m, 2H), 2.79 ppm (t, J = 8.5 Hz, 1H). An elemental analysis (YANACO,
MT-6 Corder) was carried out as: found C, 56.33, H, 6.36, N, 4.51 %, calculated for C14H19NO6: C, 56.56,
H, 6.44, N, 4.71 %.

- 48 -

2-Deoxy-2-p-methoxybenzylimideneaminio-1,3,4,6-tetra-O-decanoyl-D-glucopyranose (2)The product 1 (1.0 g, 3.36 mmol) was suspended in pyridine (10.5 g, 133 mmol, 39.5 eq.), andn-decanoic anhydride (5.49 g, 16.8 mmol, 5.0 eq.) and 4-dimethylaminopyridine (0.05 g, catalyst quantity)
were slowly added to the suspension in an ice bath under a nitrogen atmosphere. The mixture was stirred atroom temperature, followed by the dissolution of the suspension, for more than 12 h, and then the solution
was poured into deionized water. Ethyl acetate was added to the resulting solution to extract the organic
product. The organic solution was washed with saturated sodium chloride solution and deionized water, andthen was dried with anhydrous magnesium sulfate. After filtration, the solvent was evaporated and theresulting solid dried in vacuo. This product was used in the final step without purification.
2-Deoxy-2-aminio-1,3,4,6-tetra-O-decanoyl-D-glucopyranose (3), C9GLN
The crude product 2 was dissolved in 80 mL of acetone, and the solution was slowly added to 0.6 mLof 6 mol/L hydrochloric acid solution in an ice bath. The mixture was stirred for more than 12 h at room
temperature. The resulting white gel was filtered and washed with acetone. The crude product was dried invacuo overnight. The white solid was dissolved in toluene, and then was contacted with a 28 % ammonia
solution to liberate the amino group. The mixture was stirred for more than 3 h. The organic layer wascollected and washed with deionized water. The organic solution was dried with anhydrous magnesium
sulfate. After filtration, the solvent was evaporated and the resulting solid dried in vacuo to obtain a white
powder (1.86 g, 69.4 % yield). The product was identified by 1H-NMR spectrometry and FT-IR
spectrometry (SHIMADZU, FTIR-8400S). 1H-NMR (500 MHz, CDCl3) δ 5.46 (d, J = 8.7 Hz, 1H), 5.04 (m,2H), 4.25 (dd, J = 4.58 Hz, 1H), 4.09 (dd, J = 1.8 Hz, 1H), 3.82 (m, 1H), 3.00 (t, J = 9.4 Hz, 1H), 2.42-2.19(m, 8H), 1.68-1.53 (m, 8H), 1.26 (br, 48H), 1.14 (s, 2H), 0.88 ppm (t, J = 6.8 Hz, 12H); FT-IR (KBr) 3387,
3317, 2960, 2926, 2860, 1738, 1607, 1292, 1178 cm-1. The elemental analysis was as follows: found: C,
69.04, H, 10.69, N, 1.98 %, calculated for C46H85NO9: C, 69.39, H, 10.76, N, 1.76 %.
2.3 Extraction procedure
Organic solutions were prepared by dissolving the extractant in a mixture of 95 wt% of toluene and 5
wt% of 1-octanol. 1-Octanol was added as a modifier in order to improve the solubility of the extractant intoluene as well as to prevent third-phase formation during extraction. Aqueous feed solutions of Mo(VI)and W(VI) were prepared by dissolving Na2MoO4·2H2O and Na2WO4·2H2O in deionized water,
respectivery. The aqueous media (Cl-, NO3-, and SO42-) and anion concentration were controlled by adding
appropriate amounts of NaCl, NaNO3, and Na2SO4, respectively. The pH was adjusted by adding theappropriate amount of inorganic acids (HCl, HNO3, and H2SO4) or sodium hydroxide solution to theaqueous solution. Feed solutions of the cationic metals (Ni2+, Co2+ and Cu2+) were also prepared forinvestigating the selectivity of the extractant. In this case metal, chlorides, nitrates, and sulfates weredissolved in deionized water, and the concentration of anions (Cl-, NO3-, and SO42-) and the pH values were
adjusted in the same manner as for Mo(VI) and W(VI). Equal volumes of the aqueous and organic solutions
were shaken vigorously at 298 K for more than 12 h to attain equilibrium. After phase separation, the- 49 -

equilibrium pH value was measured using a pH meter (HORIBA, F-23). The concentration of metal ionsand anions were analyzed by means of an inductively coupled plasma atomic emission spectrometer(ICP-AES; SHIMADZU, ICPS-7000) and an ion chromatography (Metrohm, Compact IC 761 type),
respectively. The concentrations in organic solutions were calculated from the material valance.

OH

OH
O

OH

O

OH

(a)

OH

OH

OH

OH
NH3+Cl-N(1)

D-glucosamine hydrochloride

O

OR

OR
O

(b)

OR

O

(c)

OR

OR

OR

OR
R= - C(O)C9H19

N
(2)

OR
NH2

R= - C(O)C9H19(3)O

Scheme 1 Synthetic route for the present extractant; (a) p-methoxybenzaldehyde, 1 mol/L NaOH,(b) n-decanoic anhydride, 4-dimethylaminopyridine, pyridine, (c) (i) 6 mol/L HCl, acetone, (ii) 28 %NH3, toluene (two steps).
3. Results and Discussion
3.1 Extraction equilibria of molybdenum and tungsten in single systems
Figure 2 shows the effect of equilibrium pH values on the percentage extraction of Mo(VI) andW(VI) in chloride, nitrate, and sulfate media with C9GLN. W(VI) is effectively extracted at low pH, while
Mo(VI) is only poorly extracted. At pH >6, both metals are hardly extracted at all. Figure 3 shows thedissociation behavior of D-glucosamine [7]. If the pKa value of the amino group is assumed not to beaffected by the introduction of decanoyl groups into the hydroxyl groups, the extractant forms theammonium salt of inorganic anions (R-NH3+A- for chloride and nitrate media or (R-NH3+)2SO42- forsulphate medium, R is glucosamine matrix) at low pH. The extraction behavior is therefore concluded to beaffected by the species of the extractant.
Mo(VI) mainly exists as MoO42- in alkaline aqueous solution, and forms several oxoanion species
even at pH values < 6, e.g., HMoO4-, H2MoO4, Mo7O246-, HMo7O245-, H2Mo7O244-, and MoO22+ [8].
Alternatively, W(VI) is mainly present as WO42- in alkaline aqueous solution, and also forms several
oxoanion species in weakly acidic aqueous solution, e.g., HWO4-, H2WO4, W6O216-, HW6O215-, and- 50 -

100

key metal

80

Extraction ( % )100[ Cl- ] = 0.1 mol/L(a)key metal
Mo(VI)
W(VI)

80

Mo(VI)
W(VI)100[ NO3- ] = 0.1 mol/L

(b)

60

60

40

40

40

20

20

20

2

4

6

8

10

12

key metal
Mo(VI)
W(VI)

0

0

0

[ SO42- ] = 0.1 mol/L

80

60

0

(c)

0

2

4

6

pHe

8

10

12

0

2

4

6

8

10

12

pHe

pHe

Fig. 2 The effect of equilibrium pH on the percentage extraction of Mo(VI) and W(VI) in

1.0

1.0

0.8

0.8
OH

OH

0.6

O

O

OH
OH

OH

NH3

0.4

OH

OH

OH
+

NH2

mole fraction ( - )mole fraction ( - )(a) chloride, (b) nitrate, and (c) sulfate media; [M] = 1.0×10-4 mol/L, [extractant] = 1.0×10-2 mol/L.
1.0
H2MoO4

0.6

0

2

4

6

8

10

12

pH

H3W6O21

3-

0.6
MoO22+

0.4

H2Mo7O24

4-

HW6O215-

0.4

HMoO4-

HWO4

-

0.2
0.0

0.0

0.0

H2WO4

0.8
MoO42-

0.2

0.2

WO42-

0

1

2

3

4

5

6

0

1

pH

2

3

4

5

6

pH

Fig. 3 Distribution diagram for

Fig. 4 The mole variation of Mo(VI) and W(VI) species in aqueous

species of D-glucosamine as asolution, [M] = 1.0×10-4 mol/L.

function of pH (pKa = 7.38).
H3W6O213- [8]. Figure 4 shows the speciation of Mo(VI) and W(VI) in aqueous solution. The distribution
diagrams of Mo(VI) and W(VI) were calculated from stability constants [8]. Comparing the extraction
behavior and the species fractions of the metals in aqueous solution, the predominant extracted species forMo(VI) and W(VI) are suggested as HMoO4- and H3W6O213-, respectively. The lower extraction extent ofMo(VI) is due to the coexistence of cationic and neutral species. A mutual separation between Mo(VI) andW(VI) with C9GLN is therefore expected to be achieved in acidic aqueous solution.
Figures 5 and 6 show the effects of the concentrations of coexistent inorganic anions, Cl-, NO3-, andSO42-, on the percentage extraction of Mo(VI) and W(VI) with C9GLN, respectively. The extraction
percentage of both metals was decreased with increasing concentration of the coexistent anions in the
aqueous solution. This indicates that the anion exchange reactions between the counter anions of theammonium salt and the oxoanions of Mo(VI) and W(VI) are suppressed by the excess amounts of inorganic- 51 -

anions in the aqueous solution. The order of extraction efficiency becomes less in the order of SO42- > NO3> Cl-. Figure 7 shows the extraction isotherms for the inorganic acids, HCl, HNO3 and H2SO4 with C9GLN.
The extractability of the inorganic acids becomes greater in the order of HCl > HNO3 > H2SO4, which
agrees with the decreasing trend of extractability of the metals. This suggests that C9GLN initially reacts
with the inorganic acid to form the ammonium salt, and then the oxoanions are extracted via competitive
anion exchange with the counter anions. The proposed extraction equilibria of W(VI) from aqueous
chloride, nitrate, and sulphate solution are therefore defined as follows.
+nRNH 2 + H n A ↔ (RNH 3 ) n A n+

(1)
+

-

-

(RNH 3 ) n A n- + nHMoO 4 ↔ (RNH 3 ) n (HMoO 4 ) n + A n+

+

3-

(2)

3-

3 (RNH 3 ) n A n- + n H 3 W6 O 21 ↔ (RNH 3 ) 3n (H 3 W6 O 21 ) n + 3A n-(3)where, RNH2 and An- represents the extractant and the inorganic anions (n = 1 for Cl-, NO3-, and n = 2 forSO42-).
50

(a)

key

0.02 mol/L
0.1 mol/L
0.5 mol/L

40

Extraction ( % )50[ Cl- ](b)50

key [ NO3- ]0.02 mol/L
0.1 mol/L
0.5 mol/L

40
30

30

20

20

20

10

10

10

2.0

2.5

3.0

3.5

4.0

0
1.5

2.0

2.5

pHe

3.0

3.5

key

4.0

[ SO42- ]0.02 mol/L
0.1 mol/L
0.5 mol/L

40

30

0
1.5

(c)

0
1.5

2.0

2.5

3.0

3.5

4.0

pHe

pHe

Fig. 5 The effect of concentration of coexisting inorganic anions on the percentage extraction of Mo(VI)in (a) chloride, (b) nitrate, and (c) sulphate media, [extractant] = 1.0×10-2 mol/L.
100

100

(a)

(c)

80

)

80

60
40

[ Cl- ]

60

0.02 mol/L
0.1 mol/L
0.5 mol/L

40

key

20
0
1.5

key

(

Extraction ( % )

80

100

(b)

[ NO3- ]0.02 mol/L
0.1 mol/L
0.5 mol/L

40

2.5

3.0

pHe

3.5

4.0

0
1.5

2-

key [ SO4 ]0.02 mol/L
0.1 mol/L
0.5 mol/L

20

20

2.0

60

2.0

2.5

3.0

3.5

4.0

0
1.5

2.0

2.5

pHe

3.0

3.5

4.0

pHe

Fig. 6 The effect of concentration of coexisting inorganic anions on the percentage extraction of W(VI)in (a) chloride, (b) nitrate, and (c) sulphate media, [extractant] = 1.0×10-2 mol/L.

- 52 -

Figure 8 shows the extraction behavior of cationic metals, Ni(II), Co(II) and Cu(II) with C9GLN
in chloride, nitrate, and sulphate media, respectively. These cations were not extracted in any of theextraction systems, demonstrating that the present extractant has a high selectivity for oxoanions.

[acid] ( mol/L )0.020
key acid
HCl
HNO3

0.015

H2SO4

0.010

0.005

0.000
0.00

0.04

0.08

0.12

[acid] ( mol/L )Fig. 7 The extraction isotherms of the inorganic acids, HCl, HNO3, and H2SO4,
with C9GLN, [extractant] = 1.0×10-2 mol/L.
100

100

(a)

Extraction ( % )

80
60
40

key metal

key metal
Ni(II)
Co(II)Cu(II)
Mo(VI)
W(VI)

60[Cl- ] = 0.1 mol/L

40

60[ NO3- ] = 0.1 mol/L

40

2.4

2.8

3.2

3.6

0
1.6

Ni(II)
Co(II)Cu(II)
Mo(VI)W(VI)[ SO42- ] = 0.1 mol/L

20

20

2.0

(c)

80

80
key metal
Ni(II)
Co(II)Cu(II)
Mo(VI)
W(VI)

20
0
1.6

100

(b)

2.0

pHe

2.4

2.8

pHe

3.2

3.6

0
1.6

2.0

2.4

2.8

3.2

3.6

pHe

Fig. 8 The extraction behavior of cationic metals, Ni(II), Co(II), and Cu(II), with C9GLN
in (a) chloride, (b) nitrate, and (c) sulphate media, [extractant] = 1.0×10-2 mol/L.

3.2 Stripping of molybdenum and tungsten
Table 1 lists the stripping yield of Mo(VI) and W(VI) with several reagents. Both metals wereeffectively stripped with sodium chloride solution, suggesting that the extracted anionic species were
exchanged by an excess amount of chloride ion. The extracted W(VI) was also quantitatively stripped withsodium hydroxide solutions, because the ammonium salt in the organic phase was transformed to the freeamine by the aqueous alkaline solution.

- 53 -

Table 1 Stripping tests for Mo(VI) and W(VI)
Stripping reagent

Concentration ( mol/L )waterStripping ( % )Mo(VI)

W(VI)

-

30.4

31.8

H 2SO4

0.5

13.8

3.66

H 2SO4

1.0

10.9

4.56

NaCl

0.1

44.1

63.5

NaCl

0.5

82.9

78.6

NH3

0.15

92.5

79.2

NH3

0.3

69.0

80.5

NH3

1.5

68.1

88.2

NaOH

0.1

56.0

94.6

NaOH

0.5

55.7

96.5

NaOH

1.0

54.4

98.7

3.3 Comparison of extraction performance with commercial extractants
Figure 9 shows the effect of pH on the percentage extraction of Mo(VI) and W(VI) in sulphate
medium with C9GLN, Primene JM-T and TOA. Although the commercial extractants have higher
extractability for both Mo(VI) and W(VI) than C9GLN, the separation ability for the metals with C9GLN issuperior to the commercial extractants. The amino group in C9GLN is shielded by bulky alkyl side chainscompared with the commercial extractants as shown in Fig. 10. Since the alkyl groups may interfere withthe approach of large oxoanions to the amino group, C9GLN therefore possesses selective extractability for
W(VI).

key metal

60

key metal

80

Mo(VI)
W(VI))

Mo(VI)
W(VI)(

Extraction ( % )

80

100

(b)

60

40

20

20

20

0
2

4

6

pHe

8

10

12

Mo(VI)
W(VI)

60

40

0

key metal

80

40

0

(c)

)

100

(a)

(

100

0
0

2

4

6

pHe

8

10

12

0

2

4

6

8

10

pHe

Fig. 9 The effect of pH on the percentage extraction of Mo(VI) and W(VI) in sulphate medium with(a) C9GLN, (b) Primene JM-T, and (c) TOA, [extractant] = 1.0×10-2 mol/L, [SO42-] = 0.1 mol/L.

- 54 -

12

gray: carbon, white: hydrogen,dark gray: oxygen, black: nitrogen

Steric hindrance
OxoanionFig. 10 The effect of steric hindrance in C9GLN on the anion exchange reaction.

4. Conclusion
The extraction behavior of Mo(VI) and W(VI) with 2-deoxy-2-aminio-1,3,4,6-tetra-O-decanoyl
D-glucopyranose (C9GLN) has been investigated, with the following results. W(VI) is effectively extracted
at low pH, while Mo(VI) is poorly extracted. At high pH values, the extraction of both metals is very few.
The extraction of the metals is affected by coexisting inorganic anions, Cl-, NO3-, and SO42-, due to thecompetitive extraction between the inorganic anions and the anionic species of the metals. Since theseparation ability for the metals shown by C9GLN is greater than those of the commercial extractants,
C9GLN is thus concluded to have a good potential as an extractant for the separation of these anionic metalions.

Acknowledgement
The research was financially supported by the Sasakawa Scientific Research Grant from The Japan
Science Society [No. 19-327].

References
1. (a) K. Inoue, S. Seki, A. Matsumoto, Kichin, Kitosan Kenkyu, 4, 268 (1998). (b) K. Inoue, K.
Yoshizuka, K. Ohto, H. Nakagawa, Chem. Lett., 7, 698 (2001). (c) R. P. Dhakal, K. Inoue, K.
Yoshizuka, K. Ohto, M. Yamada, S. Seki, Solv. Extr. Ion Exch., 23, 529 (2005).
2. (a) P. Nekovár, D. Schrötterová, M. Mrnka, J. Radioanal. Nucl. Chem., 223, 17 (b) P. Nekovár and D.
Schrötterová, Solv. Extr. Ion Exch., 17, 163 (1999). (c) P. Nekovár and D. Schrötterová, Chem. Eng. J.,- 55 -

79, 229 (2000). (d) R. A. Guedes De Carvalho and M. N. M. Sampaio, Hydrometallurgy, 26, 137(1991).
3. (a) A. A. Palant, N. A. Iatsenko, V. A. Petrova, Hydrometallurgy, 48, 83 (1998). (b) N. Iatsenko
Gerhardt, A. A. Palant, V. A. Petrova, R. K. Tagirov, Hydrometallurgy, 60, 1 (2001).
4. (a) S. K. Tangri, A. K. Suri, C.K. Gupta, Trans. Indian Inst. Met., 51, 27 (1998). (b) María A. Morís,
Fernando V. Díez, José Coca, Sep. Purif. Technol., 17, 173 (1999). (c) F. Miyashita, Y. Kikuchi, G.
MIyatani, Nippon Kogyo Kaishi, 102, 35 (1986). (d) M. Sano, J. Shibata, M. Harada, S. Nishimura,
Nippon Kogyo Kaishi, 104, 49 (1988).
5. (a) M. H. H. Mahmoud, S. Nakamura, K. Akiba, Solv. Extr. Res. Dev. Jpn., 4, 23 (1997). (b) R.
Mirvaliev. K. Inoue, Solv. Extr. Res. Dev. Jpn., 8, 9 (2001).
6. D. J. Silva, H. Wang, N. M. Allanson, R. K. Jain, M. J. Sofia, J. Org. Chem., 64, 5926 (1999).
7. M. Miyazaki, S. Nishimura, A. Yoshida, N. Okubo, Chem. Pharm. Bull., 27, 532 (1979).
8. (a) Y. Sakai, I. Lindqvist, L. Siller, J. Inorg. Nucl. Chem., 9, 93 (1959). (b) G. Schwarzenbach, J. Meier,J. Inorg. Nucl. Chem., 8, 302 (1958). (c) F. Nakashio, K. Kondo, Y. Sano, F. Valenzuela, T. Tsuneyuki,
Proc. Symp. Solv. Extr., 35 (1984). (d) L. G. Sillen, A. E. Martell, “Stability Constants of Metal-Ion
Complexes Section 1”, 1964, The Chemical Society, London.

- 56 -