Hexasodium 4,4'-[1,4-phenylenebis[imino(6-chloro-1,3,5-triazine-4,2-diyl)imino]]bis[5-hydroxy-6-[(2-sulphonatophenyl)azo]naphthalene-2,7-disulphonate]

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Remarks:

decomposition after ozonation od water

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: analytical determination of decomposition pathway with sufficient documentation

Data source

Reference

Reference Type:

publication

Title:

Decomposition pathways and reaction intermediate formation of the purified, hydrolyzed azo reactive dye C.I. Reactive Red 120 during ozonation

Author:

Zhang et al.

Year:

2007

Bibliographic source:

Chemosphere 67 (2007) 712–717

Materials and methods

Test guideline

Qualifier:

no guideline required

GLP compliance:

no

Type of study / information:

decomposition via ozonation of water

Test material

Test material information

Constituent 1

Reference substance name:

Hexasodium 4,4'-[1,4-phenylenebis[imino(6-chloro-1,3,5-triazine-4,2-diyl)imino]]bis[5-hydroxy-6-[(2-sulphonatophenyl)azo]naphthalene-2,7-disulphonate]

EC Number:

269-284-3

EC Name:

Hexasodium 4,4'-[1,4-phenylenebis[imino(6-chloro-1,3,5-triazine-4,2-diyl)imino]]bis[5-hydroxy-6-[(2-sulphonatophenyl)azo]naphthalene-2,7-disulphonate]

Cas Number:

68214-04-0

Molecular formula:

C44H24Cl2N14Na6O20S6

IUPAC Name:

hexasodium 4,4'-[1,4-phenylenebis[imino(6-chloro-1,3,5-triazine-4,2-diyl)imino]]bis[5-hydroxy-6-[(2-sulphonatophenyl)azo]naphthalene-2,7-disulphonate]

Test material form:

solid: particulate/powder

Details on test material:

Procion Red H-E3B purified to > 90%

Results and discussion

Any other information on results incl. tables

The HPLC/MS analysis results show that after 30 min ozonation, the original dye cannot be detected. In fact, the color removal measured by UV/vis photospectrometer prove that the visible band at 535 nm representing of ring conjugated p system of aromatic rings connected by the azo groups was completely disappeared after 150 min.

Consequently, the apparent visible red color in the dye solution were due to the new formed dyes degraded from RR 120 and the azo group were still kept leading to the absorbance at 535 nm.

Subsequently, other small degradation products were investigated. However, the response signal (m/z 188.9 and 172.8) still could be obtained by SIM (Selected Ion Monitoring). Therefore, the direct flow injection was applied to identify further degradation products. Accordingly, SIM mode in HPLC/MS was used to confirm the ion peaks obtained by direct flow injection. The peaks of m/z 92.9, m/z 172.8 and m/z 188.9 detected in negative ion scan mode were selected to characterize by MS to obtain more fragment information from the parent ions.

Finally, in order to determine the mineralization potential of purified, hydrolyzed RR 120 and its intermediates, TOC measurements were also carried out. The remaining TOC was about 76% after 150 min of ozonation indicating relatively low mineralization efficiency. The pH of the solutions decreased rapidly within the first 30 min from 10.0 to 3.68, due to the production of organic and inorganic acid anions.

Applicant's summary and conclusion

Executive summary:

In this study, an aqueous solution of purified, hydrolyzed C.I. Reactive Red 120 (RR 120, Color Index), was selected as a model to investigate the degradation pathways and to obtain additional information on the reaction intermediate formation. The dye was purified to avoid the influence of the impurities on the ozonation process and on the formation of oxidation by-products. To simulate the dyebath effluents from dyeing processes with azo reactive dyes, a hydrolyzed form of the dye was chosen as a representative compound. High performance liquid chromatography/mass spectrometry and its tandem mass spectrometry was chosen to identify the decomposition pathways and reaction intermediate formation during the ozonation process.

In addition total organic carbon and high performance ion chromatography analysis were employed to obtain further information on the reaction processes during ozonation. Purified, hydrolyzed RR 120 was decomposed under the direct nucleophilic attack by ozone resulting in oxidation and cleavage of azo group and aromatic ring, while the triazine group still remained in the solution even after prolonged oxidation time (120 min) due to its high resistance to ozonation. Phenol, 1,2-dihydroxysulfobezene, 1-hydroxysulfonbezene were detected as the degradation intermediates, which were further oxidized by O3 and∙OH to other open-ring products and then eventually led to simple oxalic and formic acid identified by HPLC.