.

E-mail: dygserdar@gmail.com, merve_kytnci@hotmail.com, guvenc@eng.ankara.edu.tr

References:1. He, Z., Song, S., Zhou, H., Ying, H., Chen, J. 2007. C. I. Rective black 5 decolorization by combined sonolysis and ozonation. Ultrasonics Sonochemistry, 14, 298- 304.

2. İnce, N., Tezcanlı, G. 2001. Reactive dyestuff degradation by combined sosnolysis and ozonation. Dyes and pigments, 49, 145- 153.

3. Şahinkaya, S. 2013. COD and color removal from synthetic textile wastewater by ultrasound assisted electro-Fenton oxidation process. Journal of Industrial and Engineering Chemistry, 19, 601- 605.

4. Voncina, D.B., Majcen-Le-Marechal, A. 2003. Reactive dye decolorization using combined ultrasound/H2O2. Dyes and Pigments, 59, 173- 179.

5. Cuiping , B., Xianfeng, X.,Wenqi, G., Dexin, F., Mo, X., Zhongxue , G. ve Nian, X. 2011. Removal of rhodamine B by ozone-based advanced oxidation process. Desalination, 278, 84- 90.

AcknowledgementsThis research was financially supported by the Ankara University Scientific Research Project Coordination Unit (Project No: 11B4343003).

Decolorization of Reactive Dyes from Textile Wastewater by Advanced Oxidation Methods

Duygu Serdar*, Merve Kaytancı and Afife GüvençDepartment of Chemical Engineering, Ankara University, 06100 Ankara, TURKEY

Figure 6: Decolorization of RO 16 and RB 5 combined methods applied consecutively or simultaneously.

It was shown that the ozonation method alone yielded a decolorization of 13% and 98% for RO 16 at flow rates of 0.4 g/h and 5 g/h, respectively. The same analysis for RB 5 resulted in 91% and 100%. According to the these results, it can be seen that decolorization yield increses by increasing the ozone flow rate. These results also indicated that ozone treatment alone is fairly effective for both of the dyes.

The effect of frequency in the ultrasonication method used alone was investigated on the decolorization of each dye. Accordingly, treatments at 20 kHz and 30 kHz resulted in 4% and 3% decolorization for RO 16; 14% and 5% decolorization for RB 5, respectively. This result shows that ultrasound is not a suitable method to remove color from textile waste waters when it is used alone.

It was found that there is negligible difference between decolorization percentages for pH levels of 6 and 7; both result in 98% decolorization for RO 16 at 5 g/h ozone flow rate.

In the combined methods which consecutive application was investigated, it was achieved decolorization yields of 87% and 99% for RO 16 and RB 5, respectively.

The other combined method, the simultaneous application of the ultrasonication and the ozonation, was resulted the highest decolorization yield of 99% and 100% for RO16 and RB 5, respectively. This shows simultaneous combined method is more suitable than consecutive combined method in decolorization of dyes from textile waste water.

Figure 4: Decolorization of RB 5 (C0= 50 mg/l, pH= 2, time: 50 min)

Figure 5: Decolorization of RO 16 (C0= 50 mg/l, pH= 6, time: 50 min).

Figure 1: Chemical structure for (a) RO 16 and (b) RB 5.

Reactive Orange 16 and Reactive Black 5 were used in this study.

Waste waters from the textile industries are one of the most difficult ones to treat because they contain various chemicals and especially dyestuffs. Dyes usually have a synthetic origin and complex aromatic molecular structures, which make them more stable and more difficult to be biodegraded. It was reported that approximately 90% of reactive dyes, which are extensively used in the worldwide textile industry, entering activated sludge process pass through with no change; some parts can be degraded under anaerobic biological treatment but reduction products are toxic. Although the methods used for the removal of dyestuffs like ozonation, chemical reduction-oxidation, coagulation-flocculation, adsorption, are effective, most of them have some drawbacks such as high cost, formation of hazardous by-products, and intensive energy requirement. The use of advanced oxidation processes for waste water treatment has been shown to be technically feasible by numerous reports in the literature over the years [1-5].

In this study, the decolorization of Reactive Orange 16 (RO 16) and Reactive Black 5 (RB 5), in order to reference to the coloring agents contained in the waste water of the textile industry, was investigated by using ultrasound (US) at 20 kHz and 30 kHz and ozonation (OZ) at 0.4 and 5 g/h both alone and combined systems. For determining the pH effect, pH values of 2, 6,7, and 10 were studied and optimum pH was found as 6 for RO 16 and as 2 for RB 5. Among the single methods, it was found that the most effective method was the ozonation ( 5g/h) providing 98% decolorization for both dyes in 50 minutes.

Furthermore, in the combined methods which consecutive application was investigated, it was achieved decolorization yields of 87% and 99% for RO 16 and RB 5, respectively ( 50 mg/ l, 5 g/ h, 20 kHz, 50 min).

Finally, the combined method, which is the simultaneous application of the ultrasonication and the ozonation, was applied and resulted in decolorization of 99% and 100% for RO16 and RB 5, respectively (50 mg/l, 5 g/h, 20 kHz, 50 min).

Keywords: Reactive Orange 16, Reactive Black 5, decolorization, ozone, ultrasound

Summary

In single methods, the above mentioned dyes are prepared with a initial concentration of 50 mg/l (C0) in all of the experiments.The room temperature is the starting point for heat and the temperature is not specifically controlled afterwards. For US method, UP100H Heilscher Ultrasonic Homogenizer (30 kHz, 100 W) and Ultrasonic Homogenizer Sonopuls HD 3400 (20kHz); in OZ experiments, Opal ozone generator (0.4 g/ h ozone flow rate) and Waterfun ozone generator (5 g/saat) were used to determine the ultrasonic effect and the ozone dosage effect in decolorization.

Methods

Conclusions

Results

The results of single method decolorization experiments that are conducted by using the ultrasonic homogenizer (20 kHz and 30 kHz) and the ozone generator (0.4 g/h and 5 g/h) are shown in Fig. 2, 4 and 6 and Fig. 3, 5 and 6 for RB 5 and RO16, respectively.

λmax= 496 nm

λmax= 595 nm

Firstly, standard solutions of each dye were prepared to draw calibration lines in their maximum wave lengths by using Shimadzu Spectrofotometer (UV-1601).Maximum wavelengths of dyes were found as 496 nm and 595 nm for RO 16 and RB 5, respectively.

In the combined methods which consecutive application was investigated, the treatment started with the ultrasonic homogenizer, continued with the ozone generator or started with the ozone generator and ended with the ultrasonic homogenizer. Then, simultaneous application of OZ and US was investigated.

For the decolorization of RO 16 and RB 5, advanced oxidation methods consisting of only OZ (0.4 g/h or 5 g/h ozone flow rate), only US (20 kHz and 30 kHz frequency) and combined methods applied consecutively (US+OZ) or simultaneously were investigated .

Shimadzu UV 1601 Spectrofotometer

UP100H Heilscher Ultrasonic

Homogenizer

OPAL Ozone Generator

Waterfun Ozone Generator

US (20 kHz) US (30 kHz) OZ (0.4g/h) OZ (5g/h) US (20 kHz) US (30 kHz) OZ (0.4 g/h) OZ (5g/h)

OZ(5g/h)+ US(20kHz) consecutive method for RO 16

OZ(5g/h)+ US(20kHz) consecutive method for RB 5

OZ(5g/h)+ US(20kHz) simultaneous method for RO 16

OZ(5g/h)+ US(20kHz) simultaneous method for RB 5

HD 3400 Sonopuls Ultrasonic

Homogenizer

Figure 2: Decolorization of RB 5 by single US or OZ methods(C0= 50 mg/l, pH= 2)

Figure 3: Decolorization of RO 16 by single US or OZ methods(C0= 50 mg/l, pH= 6)

2nd INTERNATIONAL CONFERENCE ON

ENVIROMENTAL SCIENCE AND TECHNOLOGY14- 17 May 2014, Side, Antalya, TURKEY

Materials