Flocculation of Quaternary Chitosan on Acid Dyeing Waste Water

CHENG Dehonga, LIN Jieb, LU Shengc and LU Yanhuad*

Department of Light Chemical Engineering, Eastern Liaoning University, 325 Wenhua Road, Dandong, Liaoning, 118000, China

aemail: 14113200@qq.com,

bemail: linjieln@163.com,

cemail:lsln@aliyun.com

demail:yanhualu@aliyun.com

Keywords: flocculation, quaternary chitosan, acid dyeing, waste water treatment

Abstract. In order to increase the positively charge, solubility in water and grafted degree of chitosan,

quaternary chitosan was synthesized with chitosan and glycidyl-trimethyl-ammonium chloride by the

heterogeneous reaction. FT-IR was used to characterize the structure of the synthesized. The

quaternary chitosan was then used to treat simulated acid dyeing wastewater, the effect of quaternary

chitosan concentration, agitation mode and pH values on flocculation were discussed. The results

indicated that the H+ in nucleophilic center -NH2 was displaced by -CH2CH(OH)CH2N

+(CH3)3 and

the 2-hydroxypropyltrimethyl ammonium chloride chitosan (quaternary chitosan) was synthesized.

When applied to treatment of acid dye waste water, the decolorization rate was 95.5%, and the COD

removal was 86.4%.

Introduction

As one of the harmful and refractory organic matter waste water, dyeing sewage is of great quantity,

high colority and poor biochemical purification ability. As water soluble compounds, treatment of

acid dyes is one of the most difficult problems in industry waste water processing. The reason is that

the soluble dyes are difficult to be degraded by microbes and ordinary antioxidants in nature or in

activated sludge of treatment dyes[1,2]. Among all kinds of processing ways, the use

of polymeric flocculant has the advantage of small amounts, rapid flocculation, minor effect of salts,

pH values and temperature, small sludge yield. So use of polymeric flocculant, especially new

cationic polymeric flocculant is being concentrated stage by stage in the world[3,4]. Recently, the

researches are concerning technologies of macromolecular flocculant which has excellent removal

rateability to water soluble dyes such as polyacrylamide and their derivatives[5,6]. However, these

synthesized petroleum macromolecular flocculant have potential harmfulness to enviorement, thus

some researches are concerning on the application of chitosan, chitin and their derivatives which can

maintain the advantages of nontoxic, biodegradable, high biocompatible and can be used to treatment

of dyeing waste water in recent years[7,8].

In this work, N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (quaternary

chitosan) was synthesized by the grafting copolymerization reaction between glycidyl-trimethyl-

ammonium chloride and chitosan. Compared with chitosan, the quaternary chitosan have the high

degree of catio and bridging adsorption performance for introducing to ammomium groups. The

flocculation performances of the quaternary salt of chitosan on acid dyes was investigated. While the

quaternary salt of chitosan content, stirring way, dropping time, pH value on the flocculation effects to

dyestuff waste water were also discussed.

Experimental

Materials. Chitosan (viscosity average molecular weight is 8×105) was purchased from China

National Medicines Co. Ltd.(Beijing, China); N-(2,3-glycidyl) trimethyl ammonium chloride was

purchased from Sangong Chemical Industry Co. Ltd.(Yantai, China); Acid Red B(C. I. Acid Red

14, industrial grade); sodium hydroxide, acetic acid, alcohol, acetone, and isopropanol are all

chemical pure reagents.

Advanced Materials Research Vols. 821-822 (2013) pp 531-534Online available since 2013/Sep/18 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.821-822.531

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Quaternary chitosan preparation. Quaternary chitosan was prepared with heterogeneous method

with isopropanol as dispersion. The heterogeneous system contained 10g chitosan and 40g

N-(2,3-glycidyl) trimethyl ammonium chloride in 500 mL isopropanol, under stirring at 80°C for 12

h. The product of the reaction was then washed in the mixture of acetone and alcohol at a ratio of 1:1,

subsequently filtered and dried in a vacuum drying oven at 40°C[9].

Flocculation treatment of analogue acid dye wastewater. 100 mL Acid red B (120mg/L) was

added into 250mL flask, the different concentration of quaternary chitosan was added into the flask,

then 721Spectrophotometer was used to test the absorbance values in the upper clear liquid and

calculated the decolorization rate.

0

0)%( ratetionDecolorizaA

AA −= ����� (1)

Where A0 and A are the decolorization rate before and after flocculation respectively.

CODCr Measurement. The calculated formula of CODCr is as follows.

( )

),(10008

20 LmgO

V

cVVCODCr

×××−= (2)

Where c is the concentration of ferrous ammonium sulfate standard solution (mol/L); V0 is the

dosage of the ferrous ammonium sulfate standard solution when performing a blank titratio (mL); V

is the volume of waste water (mL); 8 is 1/2 of the molecular mass of oxigen (g/mol).

Results and Discussion

Quaternary chitosan synthesis. The FT-IR spectra of the chitosan and quaternary chitosan was

shown in Fig.1（a) and（b）.

Fig. 1 FT-IR of chitosan and chitosan quaternary ammonium salt

It was shown from Fig.1 that the FT-IR spectra of the synthesized chitosan quaternary ammonium

salt changed apparently. In the spectrum of (b), the peak at1590 cm-1

disappeared and the new peaks at

1480cm-1 and 1640cm-1

appeared. The two peaks belong to deformation vibration band and

stretching vibration band of -CH3 in quaternary group. The results indicated that the H+ in

nucleophilic center -NH2 was displaced by -CH2CH(OH)CH2N+(CH3)3 and the

2-hydroxypropyltrimethyl ammonium chloride chitosan (quaternary chitosan) was synthesized[10].

The mechanism of synthesized quaternary chitosan is shown in Fig.2.

Fig.2 Synthesis reaction of chitosan quaternary ammonium salt

532 Advances in Textile Engineering and Materials III

Fig.2 showed that there are 3 reactive groups in chitosan macromolecules, and -NH2 in C2 has

one electron pair which has strong nucleophilicity. Therefore, the -NH2 in C2 can react with epoxy

group in N-(2,3-glycidyl) trimethyl ammonium chloride and then the quaternary ammomium was

introduced into chitosan molecules.

Effects of pH values on flocculation. The concentration of analogue acid red B wastewater is

120mg/L, the concentration of quaternary chitosan is 75mg/L, pH values were adjusted from 3 to10,

fast and uniform stir for 30 seconds, then stew for 60 minutes, test the absorbance rate of the upper

clear liquid. The result is shown in Fig.3. It is found from Fig.3 that the flocculation effect of the

quaternary chitosan on acid dye was poor when pH value is lower than 6 because there were

high-density positive charge of –NH4 in the aqueous solution, and the similarly charged colloidal

particles cannot come close enough together to agglomerate intolarger particles. When pH value was

6, the density positive charge of –NH4 in quaternary chitosan solution was up to the best flocculation

effect. When pH, was more than 6, the negative change was gradually negative the positive charge of

quaternary chitosan, the flocculation effect was became weak. Therefore, pH value was selected 6.

Effects of quaternary chitosan concentration on flocculation. The treatment of dyeing waste water

is ordinary performed in neutral condition. In this work, pH value was determined 6, magnetic stir

was selected 30r×30s, and rest for 60 minutes. The absorbance values at different concentrations of

quaternary chitosan were shown in Fig.4.

0102030405060708090100

2 3 4 5 6 7 8 9 10pHDecolorization rate (%)

0102030405060708090100

0 25 50 75 100 125 150 175 200Concentration of quaternary chitosan (mg/L)

Deco

lori

zati

on

rat

e (

%)

Fig.3 Effect of pH values on acid dye

flocculation

Fig.4 Effect of quaternary chitosan

concentration on acid dye flocculation

It was shown from Fig.4 that the decolorization rate increased with the increase of quaternary

chitosan concentration and reached a maximum when quaternary chitosan was 100 mg/L. When the

quaternary chitosan concentration was greater than 100 mg/L, the decolorization rate decreased. The

reason is that the flocculation action is mainly adsorption bridging mechanism. When the

concentration is low, the flocculating action was not occured, and the excessive application

of flocculating agent may produced saturation phenomenon on the surface of colloidal particles. And

then the flocculating agent could disconnected from thesurface of the bridging flocculated

colloidal particles and return to its surface of the original colloidal particle and was in the stable state

again. Therefore, quaternary chitosan concentration was selected 100 mg/L.

Effects of stirring on flocculation. The fast stirring process include the following two aspects: one is

disperse action of flocculating agent, and the other is the formation process of the small dye

flocculating constituent in solution. While slow stirring process is benefit to dye absorptoin for

flocculent. Therefore, the suitable stirring speed should be selected to ensure the high flocculating

effect. In this experiment, pH value was 6, quaternary chitosan concentration was 100mg/L, the

solution was then rest for 60 minutes. The decolorization rate of different stirring manner of

quaternary chitosan flocculation is shown in Table 1.

Advanced Materials Research Vols. 821-822 533

Table 1 Effect of stirring manner on acid dye flocculation

No. Stirring manner Decolorization rate (%)

1 30r×3min+10r×5min 93.7%

2 30r×3min +20r×5 min 88.1%

3 30r×3min +30r×5 min 77.5%

4 30r×3min +40r×5 min 76.4%

5 60r×3min +10r×5 min 95.5%

6 60r×3min +20r×5 min 90.3%

7 60r×3min +30r×5 min 83.0%

8 60r×3min +40r×5 min 80.2%

Table 1 indicated tha t the better stirring manner is as follows: stirring at speed of 30 r/min for 3

min, then 40 r/min for 5 min, the decolorization rate was 95.5%.

According above discussion, the maximum flocculating codition was detemind as follows: stirring

at a speed of 30 r/min for 3 min, then 60 r/min for 5 min, the decolorization rate was up to 95.5%, in

this cased, the COD removal was 86.4%.

Conclusion

Quaternary chitosan was synthesized with glycidyl-trimethyl-ammonium chloride and chitosan by the

heterogeneous reaction, and the FT-IR analysis indicated the formation of quaternary chitosan. The

maximum flocculating codition was as follows: stirring at a speed of 30 r/min for 3 min, then 60 r/min

for 5 min. In this condition, the decolorization rate was up to 95.5%, in this cased, the

COD removal was 86.4%.

Acknowledgements

This work was financially supported by Liaoning Excellent Talents in University(LJQ2011138),

Natural Science Foundation of Liaoning Province (No.201202081), Program of Eastern Liaoning

University (No. 2013 y023) and the Foundation of Key Discipline Project of Liaoning Province

Universities (No. 2012310).

References

[1] Y. Li, A. H. Lu, S. Jin and C. Q. Wang. J. Hazard. Mater. Vol. 170 (2009), p. 479

[2] B. Balamurugan, M. Thirumarimurugan and T. Kannadasan. Bioresource. Technol. Vol. 102

(2011), p. 6365

[3] I. G. Lalov, I. I. Guerginov, M. A. Krysteva and K. Fartsov. Water. Res. Vol. 34 (2000), p. 1503

[4] R. J. Zemaitaitiene, E. Z. R. Klimaviciute and A. Zemaitaitis. Colloid. Surface. A. Vol. 214

(2003), p. 37

[5] X. Z. Tian, E. Ren, J. H. Wang, J. L. Zou, Y. Tao, S. Wang and J. G. Xue. Carbohydr. Polym. Vol.

87(2012), p. 1956

[6] Q. L. Chen, Y. Y. Du, L. Shen, Y. J. Xing and J. J. Dai. Dye. Finish. J. Vol. 17 (2010), p. 1

[7] H. K. No, S. P. Meyers. Rev. Environ. Contam. Toxicol. Vol.163(2000), p.1

[8] V. K. Konaganti, R. Kota, S. Patil and G. Madras. Chem. Eng. J. Vol. 158(2010), p. 393

[9] Y. H. Lu, Z. M. Liu and J. Lin. Text. Res. J. Vol. 31 (2010), p. 88

534 Advances in Textile Engineering and Materials III

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