Fourier Transform Infrared Spectroscopy Study on Cation  

adsorption on Viscose Rayon Succinate  
 

Khasbaatar Dashkhuu
1
 and Ung Su Choi

2 

 
1
Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences,  

Peace avenue 13330, Ulaanbaatar 210351, Mongolia. 
2
Energy Mechanics Research Center, Korea Institute of Science and Technology, Seongbuk gu,  

Hawolgok dong 39-1,Seoul, Korea. 

 

Abstract: Ion-exchange materials have been considered as suitable material for the recovery of 

heavy metals in water. A viscose rayon succinate, synthesized from viscose rayon and succinic 

anhydride in presence of DMSO, to remove trace bivalent metal ions such as Ag
+

, Cu
2+

, Ni
2+

, Pb
2+

, 

Zn
2+

 and Cr
3+

, was studied using FT-IR for the behavior of metal adsorption. Both esterification and 

carboxyl bonding of viscose rayon succinate were assigned essentially at 1729 and 1693cm
-1

, 

respectively. And the essential band of bonding between metal and the material was determined at 

1625cm
-1

. The available adsorption capacity of this fiber was 6.2mequiv/g. The adsorption of metal 

ions on the viscose rayon succinate follows the order of Cu
2+

>Cr
3+

>Ni
2+

>Pb
2+

>Zn
2+

>Ag
+
 with 

maximum adsorptions capacities 4.2, 1.42, 0.91, 0.83, 0.69 and 0.35 mmol/g, respectively.  

 
Keywords:  chelating fiber, cellulose, viscose rayon, metal adsorption, carboxyl group, FT-IR, pH selectivity 

 

 

Introduction 

s the high rate of industrial 

development in the world, 

contaminants of heavy metals in 

wastewater originated from industries are 

increasing as that influence to the balance of 

our environment as well as human life. Some 

cancers and serious diseases may be caused 

from these metals [1-3]. There are lots of 

methods including chemical precipitation [4], 

electrolytic methods [5], and adsorption onto 

activated carbon [6], membrane process [7], 

and chelating polymer [8] to reduce the heavy 

metals in wastewater.  

More recently, researches have been 

undertaken to extend to the design of 

polymeric based ion-exchange fibers for the 

removal of heavy metals. Several of designs 

and applications of chelating fibers have 

received increased attraction and been 

investigated [8-10]. In particular, scientists 

have intensified many efforts to modify fibers 

in such a way that inherent fiber properties 

are preserved [11]. Whereas, most chelating 

polymers are composed of petroleum-based 

synthetic polymers [12-14]. Furthermore, the 

used synthetic chelating polymers often 

produce on secondary environmental 

pollution by contaminating the soil or air. In 

addition, these are usually nonrenewable and 

nondegradable [14]. 

Viscose rayon is regenerated from cellulose 

which has renewability [15] and 

biodegradability [16] and there is more 

cellulose on earth than any other organic 

substance [17].  Cellulose itself has a very 

low ion exchange capacity [18, 19]. The ion-

exchange properties of cellulose are similar to 

other ion exchange resins, but cellulose ion 

exchangers are more finely divided than 

A 

136

p 136-141



ordinary ion exchange resins, present a larger 

surface, because of their porous structure, 

permit the entrance or attachment of larger 

molecules which are not readily adsorbed by 

other resins. The rate of exchange is also very 

rapid in the case of cellulose ion exchangers 

[19]. One very attractive feature of cellulose 

is its chemical composition, with a large 

amount of relatively easily accessible 

hydroxyl groups that can be used for 

attachment of a variety of functional groups. 

Succinic groups can introduce at positions 

C2, C3, and C6 of each anhydroglucose unit, 

where available hydroxyl groups exist, in 

viscose rayon. The vicinal carboxyl groups of 

succinate are separated by a single bond and 

are free rotation which allows more flexibility 

in accommodating the special requirements of 

larger cations [20]. 

In this study, carboxylic acid functionalities 

were introduced to viscose rayon by chemical 

modification of succinic anhydride in 

presence of DMSO. The modified viscose 

rayon was then characterized by Fourier 

transform infrared, 
13

C nuclear magnetic 

resonance spectroscopes and SEM. 

Adsorption behavior of metal ions such as 

silver, copper, zinc, nickel, lead and 

chromium on the synthesized viscose rayon 

succinate were demonstrated using 

quantitative analyses and FT-IR under various 

pH which is one of the fundamental 

characteristics of aqueous solutions.  

 

Experimental 
Materials.Viscose rayon felt, succinic 

anhydride and Dimethylsulfoxide /DMSO/ 

were used for substrate, reagent and solvent 

and purchased from /company of viscose 

rayon/, Dea Jung chemicals & metals CO., 

Ltd., Korea, respectively. Ag(NO3), 

Cu(NO3)2∙xH2O, Ni(NO3)2∙6H2O, 

Zn(NO3)2∙6H2O, Pb(NO3)2 and CrCl3∙6H2O 

(Sigma Chemical Co.) were utilized for 

testing of being absorbed those metal ions on 

the ion-exchanger and, 1N NaOH and 1N 

HNO3 were supplied from Sigma Chemical 

Co. 

Synthesis of ion-exchange viscose rayon. 

An ion-exchange viscose felt was 

synthesized from viscose rayon felt (ca. 10cm 

x 10cm, 5g and 2.8mm thick), succinic 

anhydride (50g), and DMSO(500ml) for 5h at 

80
0
C with spin. The synthesized viscose 

rayon succinate washed by cold and hot 

distilled water and dried in a freeze drier at -

50
0
C, 5 Torr , for 24 hours.  

Measurements. Fourier transform infrared 

spectra (4000-200cm
-1

, KBr disc) were 

recorded on a GX FTIR, PerkinElmer 

spectrometer. 
13

C NMR was taken on Bruker 

MSL200 spectrometer in the solid state. The 

polymers were investigated in a scanning 

electron microscopy (SEM). The pH values 

were measured using a pH 300 (Hanna 

Instruments) digital pH meter. The 

quantitative analysis of adsorbed ions was 

carried out with atomic adsorption 

spectrophotometry (AAS; SpectraAA 800, 

Varian). 

Quantitative analysis of the adsorption of 

Ag
+

, Cu
2+

, Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+ 

100 ml and pH adjusted solutions including 

10mM Ag
+

, Cu
2+

, Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+

, 

separately, and 0.1g of the viscose rayon 

succinate were placed in Erlenmeyer flasks 

and shaken for 24 h at 200rpm. The 

concentration of ionic metal not removed 

from the solution was determined by AAS. 

The chelating fibers with metal were dried at 

40
0
C in a vacuum oven for 24 hours and 

characterized by FT-IR spectrometer. In this 

study, the concentrated HNO3 was used to 

adjust the pHs of metal ion aqueous solutions. 

In order to obtain an adsorption capacity of 

the chelating fiber, 0.1g of the viscose rayon 

succinate and 100ml of 0.1N NaOH solution 

in an Erlenmeyer flask was shaken for 24 h at 

200rpm, then a 30ml of solution sampled 

from the shaken solution was measured using 

an auto-titrator (Metrohm 728, Swiss) 

utilizing a 0.1N HCl solution as back titration. 

 

Results and Discussion 

The viscose rayon succinate was 

successfully synthesized from viscose rayon 

and succinic anhydride in presence of DMSO 

(scheme 1). The adsorption capacity of the 

viscose rayon succinate is 6.2meq/g.  

Figure 1 shows 
13

C NMR of viscose rayon 

and the chelating fiber. The application of 
13

C 

NMR is more successful than 
1
H NMR for the 

study of cellulose and cellulose derivatives 

[21]. The chemical shifts carbons in viscose 

137



rayon (A) are obtained as typical chemical 

shifts of cellulose. Resonances for the internal 

(b) and (d) carbons in viscose rayon and 

viscose rayon succinate are observed at 105 

and 87.3ppm, and 105 and 88ppm, 

respectively.   Obviously, it is seen that no 

degradation is occurred in terms of the 

synthesizing according to that almost no 

chemical shifts of (b) and (d) carbons of the 

viscose rayon succinate are significantly 

observed. In 
13

C NMR spectra of (B), four 

chemical shifts (g), (h), (i), (j) of carbons are 

assigned at 173.8, 176, 39.8, and 29.9ppm, 

respectively. Those signals can demonstrate 

succinic groups successfully introduced on 

viscose rayon, in particularly resonance line 

for the (g) of the viscose rayon succinate at 

173.8ppm [29]. The signals are shown in 

table 1. 

 

 
Fig. 1, 

13
C NMR spectra of (a) VR and (b) VRS 

 

Typical SEM image of the viscose rayon 

which has a diameter of 9m, exhibits a 

characteristic serrated surface [12] in Fig.2(a). 

A surface of the viscose rayon succinate is 

shown in Fig.2(b). A slight difference of the 

viscose rayon succinate can be observed 

surface rougher than that of the viscose rayon. 

 

 
Fig. 2, SEM images of (a) Viscose rayon and (b) 

Viscose rayon succinate. 

 

FT-IR spectra of viscose rayon felt (a), the 

viscose rayon succinate (b), the viscose rayon 

succinate with metal complexes such as Cu
2+

 

4.2mmol/g at pH 5 (c), Ni
2+

 0.91mmol/g at 

pH 6 (d),  Zn
2+

 0.69mmol/g at pH 6.3 (e), 

Pb
2+

 0.83mmol/g at pH 5 (f), Ag
+
 0.35mmol/g 

at pH 8 (g), and Cr
3+

 1.42mmol/g at pH 4 (h) 

are shown in Fig. 3. All of IR spectra exhibit 

a broad and intense band in the 3000-3700cm
-

1
 region which is assigned to free and 

hydrogen bonded OH stretching vibration. In 

most hydrocarbons, the CH2 asymmetric 

stretch is near 2930 cm
-1

. The IR spectra 

except viscose rayon are characterized by 

absorption a symmetrical band around 2930 

cm
-1

 (CH2 and CH groups) and this band is 

switched from absorption peak at 2891cm
-1

, 

which is assigned to symmetric band CH of 

viscose rayon. A peak at 1644 cm
-1

 was 

assigned to water absorption in viscose rayon. 

Despite a peak of viscose rayon spectrum is 

observed at 1160 cm
-1

, it should be mentioned 

that the very strong band at 1163 cm
-1

 is 

assigned to the C-O stretching in the esters 

(O(C=O)CHCH2) of viscose rayon succinate. 

Carboxylic esters, and carboxylic acids show 

a strong C=O stretching absorption band in 

the region of 1870-1540cm
-1 

[22]. This sharp 

peak is not observed in spectra of viscose 

rayon. 

New strong peaks of viscose rayon 

succinate with metal ions such as Ag
+

, Cu
2+

, 

Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+

, appeared at a range 

of 1721-1739 cm
-1

.  

Furthermore, not big intensity peaks were 

found at 1639cm
-1

, 1623cm
-1

, 1641cm
-1

, 

1546cm
-1

, 1639 cm
-1

, and 1737 cm
-1 

corresponded to ionic bonding formed 

between COO
-
 with Ag

+
, Cu

2+
, Ni

2+
, Pb

2+
, 

Zn
2+

 and Cr
3+

, respectively. The bonds 

between carboxyl groups and metals can 

influence to the intensity of peak of carboxyl 

group of the viscose rayon succinate. It is 

explained that the band of carboxyl groups 

with metal shifted to low frequency because 

of this bond to hinder vibration of carboxyl 

groups. On the other hand, the absorption of 

the carboxyl group shifted to lower 

wavelength was attributed to the absorption of 

carboxyl group with metals according to the 

formation of the chelating complex which 

weakens the double bonding property of 

carbonyl groups owing the coordinate bond 

between oxygen atoms of carbonyl groups 

and metal ions [23]. In general, there is a 

138



correlation between frequency of peak 

attributed to carboxyl-metal bond and the 

ionic radii. This result indicates that the ionic 

radius increases, the frequency decrease [24, 

25]. Definitely, the formation of the chelate 

ring and its resultant geometry has a direct 

effect on the COO
-
 bond. It is interesting to 

note that frequency of Zn
2+

 is higher than 

Cu
2+

. The peak assigned at 1639cm
-1

 of 

viscose rayon succinate with Zn
2+

 

corresponds to a syn-syn bridging carboxylate 

ligand [26]. 

 

(h)

 

 

 4000               3000               2000              1500               1000               500

Wavenumbers (cm
-1
)

A
b
so

rp
ti

o
n
s 

(A
b
s.

 u
n
it

s)

(a)

(b)

(c)

(d)

(e)

(f)

(g)

 
Fig. 3. FT-IR spectroscopy of (a) VR, (b) VRS, VRS with 

metal ion complexes: (c) Cu
2+

 4.2mmol/g at pH 5, (d) Ni
2+

 
0.91mmol/g at pH 6, (e) Zn

2+
 0.69mmol/g at pH 6.3, (f) Pb

2+ 

0.83mmol/g at pH 5, (g) Ag
+ 

0.35mmol/g at pH 8, and (h) 
Cr

3+ 
1.42mmol/g at pH 4. 

 

Figure 4 shows quantitative analyses of 

heavy metals adsorbed on the viscose rayon 

succinate under increasing pH. The difference 

between heavy metal ions adsorbed on the 

viscose rayon succinate attributes with the 

chemical and physical properties of metal 

ions and chelating agent in pH range of 1.0-8. 

For increasing pH, the behavior of the viscose 

rayon succinate turns to more reactivity with 

metals. In acid medium, the viscose rayon 

succinate is highly protonated and it reduces 

the attracting effect of the metal ion due to 

lack of negative charge. The 4.28 mMol of 

Cu
2+

 in 1 liter aqueous solution adsorbed on a 

gram of the viscose rayon succinate at pH 

5.01 is the maximum adsorption. As seen 

figure 4, the maximum adsorptions of metal 

ions can be ordered as Cu
2+

>Cr
3+

>Ni
2+

 

>Pb
2+

>Zn
2+

>Ag
+
. Cu

2+ 
was much more 

quantity as compared from other metal ions 

under the same conditions. The values of Kf , 

defined as  the formation rate constants 

between COO
-
 and Metal ions, increase with 

the charge of the metal ion. Kf values of Ag
+

, 

Cu
2+

, Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+

, were found to 

be 1.5x10
12

, 7.5x10
9
, and 3x10

7
 for CH3COO

-

, respectively [27]. Moreover, the equilibrium 

quotients (LogK) represent also the same 

order as 2.3, 2.01, and 1.08 [28] for Cu
2+

, 

Pb
2+

, and Zn
2+

, respectively. The adsorptions 

under the pH range were also investigated 

through FT-IR spectroscopy.  

1 2 3 4 5 6 7 8

0,0

0,5

1,0

1,5

2,0

2,5

 

 

A
d
so

rp
ti

o
n
 (

m
m

o
l/

g
)

pH

 Ag
+

 Cu
2+

 Ni
2+

 Zn
2+

 Pb
2+

 Cr
3+

  
Fig. 4. Effect of pH on the adsorption of Ag

+
, Cu

2+
, 

Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+ 

 

FT-IR spectra of Cu
2+

, which is on behave 

of spectra of Ag
+

, Ni
2+

, Pb
2+

, Zn
2+

 and Cr
3+

 

ions, adsorbed on the viscose rayon succinate 

with increasing pH are shown in figure 5. The 

intensities observed at 1724 cm
-1

, 3436cm
-1

 

and attributed to ionic bonded between 

carboxyl and copper, and hydrogen bonded 

OH, respectively, decreased with decreasing 

pH. A reason of the decreased intensity at 

3436cm
-1

 (O-H…O) is that the number of 

hydroxide carried by metal ions was 

decreased due to the reduced amount of metal 

ions bonded with the chelating fiber. At the 

same time by decreasing pH, the intensity of 

the peak assigned at 1736cm
-1

 (C=O) 

increased as switching from reduced amount 

of ionic bonds between carboxyl group and 

copper. The peak observed at 1656cm
-1

 

assumed to the bond shown in fig.6. (b) due 

to oxygen of a single carboxyl do not depend 

each other through the metal ion. Moreover, 

Fig. 6 (a) they linked through the metal ion. 

In this case, their vibration is hindered and 

calculated to lower frequency. 

139



(f)

(e)

(d)

(c)

(b)

(a)

4000            3000             2000               1500            1000              500

 

 

A
d
s
o

rp
ti
o

n
 (

a
d

s
. 
u
n

it
s
)

Wavenumbers (cm
-1
)

 

 
Fig.5. FT-IR spectra of VRS and VRS  with Cu

2+
 

increasing pH; (a) pH 2.5;  (b) pH 3;  (c) pH 3.5;  (d) 

pH 4; (e) pH 4.5; (f) pH 5 

 

Conclusions 

In this study, viscose rayon succinate 

(chelating fiber) was synthesized from 

viscose rayon and succinic anhydrate in 

presence of DMSO. The synthesis was 

successfully confirmed by 
13

C NMR and FT-

IR. Moreover, a new very strong peak 

appearing at 1733cm
-1

 was attributed to C=O 

bonds. The general trends of decreasing 

frequency with increasing ionic radii, which 

were observed for the viscose rayon succinate 

metal ions complexes, were confirmed in the 

FT-IR spectra. An adsorption capacity of the 

viscose rayon succinate was 6.2meq/g. 

Identical feature for each adsorptions 

frequency decreasing with decreasing pH 

were observed. The maximum metal ions 

adsorbed can be classified as Cu
2+

>Cr
3+

>Ni
2+

 

>Pb
2+

>Zn
2+

>Ag
+
 and such as 4.2mmol/g, 

1.42mmol/g, 0.91mmol/g, 0.83mmol/g, 

0.69mmol/g, 0.35mmol/g, and respectively. 

Amount of adsorption Cu
2+

 on viscose rayon 

succinate is much higher than other metal 

ions under the same conditions.  

 

Acknowledgement 

The authors would like to acknowledge the 

financial support from Korea Institute of 

Science and Technology. 

 

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