Reactive Azo Dyes

Although it has been reported (138) that decolorization of wastewater containing reactive azo dyes with sodium hydrosulfite is possible only to a limited extent, others have demonstrated good reduction (decolorization). For example, using zinc hydrosulfite for the decolorization of dyed paper stock (139) resulted in color reduction of 98% for azo direct dyes (139). A Japanese patent (140) describes reducing an azo reactive dye such as Reactive Yellow 3 with sodium hydrosulfite into its respective aromatic amines which ate more readily adsorbable on carbon than the dye itself. This report has been confirmed with azo acid, direct, and reactive dyes (22). 

There is some need for new pH indicators with improved characteristics which allow also covalent binding. P. Makedonski report about new kind of reactive azo dyes and their application as reversible pH sensors35. They prepare a new pH indicating sensors based on thin films prepared from azo dyes that are covalently bonded by an acetal linkage to a vinylalcohol ethylene copolymer (Figure 7). The absorption spectra of the polymer bond... 

Makedonski P., Brandesa M., Grahnb W., Kowalsky W., Wichem J., Wiese S., Johannes H., Synthesis of new kinds of reactive azo dyes and their application for fibre-optical pH-measurements, Dyes and Pigments 2004 61 109-119. 

Pseudomonas luteola Reactive azo dyes, Direct azo dyes and leather dyes The 59-99% color removal after 2-6 days static incubation, at dye concentration of 100 mg L 1, monoazo dyes showing fastest rate of decoloration [78]... 

Pearce Cl, Christie R, Boothman C et al (2006) Reactive azo dye reduction by Shewanella strain J18 143. Biotechnol Bioengin 95 692-703... 

Padmavathy S, Sandhya S, Swaminathan K (2003) Comparison of decolorization of reactive azo dyes by microorganisms isolated from various sources. J Env Sci 15 628-633... 

The color index (Cl) number, developed by the society of dyers and colorists, is used for dye classification. Once the chemical structure of a dye is known, a fivedigit Cl number is assigned to it. The first word is the dye classification and the second word is the hue or shade of the dye. For example, Cl Acid Yellow 36 (Cl 13065) is a yellow dye of the acid type. Additionally, a dye mixture may consist of several dyes for example, Navy 106 is composed of three reactive azo dyes remazol black B (Reactive Black 5), Remazol Red RB (Reactive Red 198), and Remazol Golden Yellow 3. 

Carliell CM, Barclay SJ, Naidoo N et al (1995) Microbial decolourasition of a reactive azo dye under anaerobic conditions. Water SA 21 61-69... 

Gottlieb A, Shaw C, Smith A et al (2003) The toxicity of textile reactive azo dyes after hydrolysis and decolourisation. J Biotechnol 101(l) 49-56... 

Supaka N, Juntongjin K, Damronglerd S et al (2004) Microbial decolorization of reactive azo dyes in a sequential anaerobic-aerobic system. J Chem Eng 99 169-176... 

Dos Santos AB, Cervantes FJ, Yaya-Beas RE et al (2003) Effect of redox mediator AQDS on the decolourisation of a reactive azo dye containing triazine group in a thermophilic anaerobic EGSB reactor. Enzyme Microb Technol 33 942-951... 

Van derZeeFP, BouwmanRHM, StrikDPBTB et al (2001) Application of redox mediators to accelerate the transformation of reactive azo dyes in anaerobic bioreactors. Biotechnol Bioeng 75 691-701... 

Lourenco ND, Novais JM, Pinheiro HM (2006) Kinetic studies of reactive azo dye decolorization in anaerobic/aerobic sequencing batch reactors. Biotechnol Lett 28 733-739... 

Lin HY, Leu JY (2008) Kinetic of reactive azo-dye decolorization by Pseudomonas Luteola in biological actived carbon process. Biochem Eng J 39 457 167... 

Marco SL, Albino AD, Ana S et al (2007) Degradation of a textile reactive Azo dye by a combined chemical-biological process Fenton s reagent-yeast. Water Res 41 1103-1109... 

Forss J, Welander U (2009) Decolourization of reactive azo dyes with microorganisms growing on soft wood chips. Int Biodeterior Biodegradation 63 752-758... 

Yu G, Wen X, Li R, Qian Y (2006) In vitro degradation of a reactive azo dye by crude ligninolytic enzymes from nonimmersed liquid culture of Phanerochaete chrysosporium. Process Biochem 41(9) 1987-1993... 

Maximo C, Amorim MTP, Costa-Ferreira M (2003) Biotransformation of industrial reactive azo dyes by Geotrichum sp. CCMI 1019. Enzyme Microb Technol 32 145-151... 

Yang Q, Lib C, Li H et al (2009) Degradation of synthetic reactive azo dyes and treatment of textile wastewater by a fungi consortium reactor. Biochem Eng J 43 225-230... 

The tolerance to high pHs is important in particular for industrial processes using reactive azo dyes, which are usually performed under alkaline conditions. A strain of C. bifermentans selected from a contaminated soil was tested for the ability to decolorize Reactive Red 3B-A at pHs from 5 to 12 while no decolorization was observed at pH 5, the dye was nearly completely decolorized across a broad range of pH values (6-12) after 48 h of incubation in this study a previous analysis of UV/Vis spectra of Reactive Red 3B-A, Reactive Black 5, and Reactive Yellow 3G-P after 0, 12, 24, and 36 h incubation was carried out, showing different decolorization rates for the three dyes, with no change in color content in the abiotic control [5]. 

Carliell CM, Barcaly SJ, Shaw C, Wheatly AD, Buckley CA (1998) The effect of salts used in textile dyeing on microbial decolorization of a reactive azo dye. Environ Technol 19 1133-1137... 

Normal-phase TLC has been employed for the control of the synthesis of some new reactive azo dyes containing the tetramethylpiperidine fragment. The chemical structure of the basic molecule and the substituents of the new derivatives are shown in Fig. 3.16. The new derivatives were characterized by their RF values determined in different mobile phases. Compositions of mobile phases were n-propanol-ammonia (1 1, v/v) for dye 1.2 (Rp = 0.84) n-propanol-ammonia (2 1, v/v) for dyes 1.3 (RF = 0.50) and 1.4 (RF = 0.80) and n-heptane-diethyl ether (1 1, v/v) for dyes 1.5 (RF = 0.80) and 1.6 (RF = 0.76). The results indicated that together with other physicochemical methods such as IR and H NMR, normal-phase TLC is a valuable tool for the purity control and identification of new synthetic dyes [96],... 

B. -Y. Chen, Understanding decolorization characteristics of reactive azo dyes by Pseudomonas luteola toxicity and kinetics. Proc. Biochem., 38 (2002) 437 446. 

M. Muruganandham and M. Swaminathan, Photochemical oxidation of reactive azo dye with UV-H202 process. Dyes Pigm. 62 (2004) 269-275. 

M. Adosinda, M. Martins, N. Lima, A.J.D. Silvestre and M.J. Queiroz, Comparative studies of fungal degradation of single or mixed bioaccessible reactive azo dyes. Chemosphere, 52 (2003) 967-973. 

P Petrova-Miladinova and T.N. Konstantinova, On the synthesis of some reactive azo dyes containing tetramethylpiperidine fragment. Dyes Pigm., 67 (2005) 63-69. 

M. Neamtu, I. Siminiceanu, A. Yediler and A. Kettrup, Kinetics of decolorization and mineralization of reactive azo dyes in aqueous solution by the UV/H202 oxidation. Dyes Pigm., 53 (2002) 93-99. 

M. Neamtu, A. Yediler, I. Siminiceanu and A. Kettrup, Oxidation of commercial reactive azo dye aqueous solutions by the photo-Fenton and Fenton-like processes. J.Photochem. Photobiol.A Chem., 161 (2003) 87-93. 

Ambrosio, ST Campos-Takaki, GM. Decolorization of reactive azo dyes by Cunninghamella elegans UCP 542 under co-metabolic conditions. Bioresource Technology, 2004 91, 69-75. 

Benkli, YE Can, MF Turan, M elik, MS. Modification of organo-zeolite surface for the removal of reactive azo dyes in fixed-bed reactors. Water Research, 2005 39, 487-493. 

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