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Reaction mass of sodium(E)-6,7'-carbonylbis(azanediyl)bis(4-hydroxy-3-((E)-phenyldiazenyl) naphthalene-2-sulfonate) and disodium 3-[(4-acetamidophenyl)azo]-4-hydroxy-7-[[[[5-hydroxy-6-(phenylazo)-7-sulphonato-2-naphthyl]amino]carbonyl]amino]naphthalene-2-sulphonate and disodium 7,7'-(carbonyldiimino)bis[4-hydroxy-3-(phenylazo)naphthalene-2-sulphonate]
EC number: 939-268-7 | CAS number: -
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
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- Toxicological Summary
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- Acute Toxicity
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- Repeated dose toxicity
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- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
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- Additional toxicological data

Additional information on environmental fate and behaviour
Administrative data
- Endpoint:
- additional information on environmental fate and behaviour
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: No GLP, no guidelines followed
Cross-reference
- Reason / purpose for cross-reference:
- reference to same study
Data source
Reference
- Reference Type:
- publication
- Title:
- Optimization and effects of some electron acceptors on the photocatalytic degradation of Direct Red 23 azo dye
- Author:
- Débora N. Clausen, Ieda S. Scarminio and Keiko Takashima
- Year:
- 2 008
- Bibliographic source:
- J. Chil. Chem. Soc., 54, Nº 3 (2009)
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Deviations:
- not applicable
- Principles of method if other than guideline:
- The photocatalytic degradation of direct red 23 (DR23), was carried out in TiO2 suspension at 30ºC with the use of artificial and solar light sources. The photoreaction followed the first-order behavior with respect to the azo dye as a function of irradiation time. A 2^3 factorial design was carried out, in order to obtain the best experimental conditions, using the rate constant of DR23 degradation as the analytical response. Seven chemical species were determined from the normalized UV-Vis spectra during the DR23 degradation through Imbrie Q mode factor analysis followed by varimax and Imbrie oblique rotations. The addition of electron acceptors, such as H2O2, S2O82-, and ClO3- on the optimized conditions, was carried out to increase the DR23 degradation rate. Comparison of degradation efficiencies under artificial and solar radiation was examined in the presence of oxidants.
- GLP compliance:
- no
- Type of study / information:
- Degradation and decolorization
Test material
- Reference substance name:
- Direct Red 23
- IUPAC Name:
- Direct Red 23
Constituent 1
Results and discussion
Any other information on results incl. tables
Decolorization and degradation of irradiated sample
The highest response of the rate constant (5.59x10-3 min-1) was obtained by irradiating 1.50x10-4 mol/L DR23 in a suspension containing 1.75 g/L TiO2 at the natural pH (6.9) and at 30.0°C. The decrease of the natural pH from 6.9 to 4.4 for the fastest decolorization after 6 h irradiation was attributed to the proton transfer and hydroxyl radical production in the valence band by the water molecule. The most important parameters which affect the decolorization rate constant, were the substrate (DR23) and semiconductor concentrations (TiO2). On the other hand, semiconductor and substrate concentrations showed a significant synergic effect on of the decolorization rate constant (1.72±0.123 x 10-3 min-1).
The color remove is attributed to the rupture of the double bond between the two nitrogen atoms (–N=N-) and related as the most active site for oxidative attack. The decrease of the bands with maximum absorptions at 240 and 310 nm indicates the disappearance of the aromatic groups. Results indicate the existence of seven chemical species for the DR23 degradation.
Effect of electron acceptors
In order to enhance the formation of hydroxyl radicals and also inhibit undesired electron/hole pair recombination, and hence permit the degradation of highly toxic wastewater to become faster and easier some electron acceptors were added to the TiO2 suspension containing direct red 23. There is no observable loss of dye, since the rate constants remained practically constant during the irradiation.
Hydrogen peroxide
The initial pH decreased respectively to 6.8 and 6.5 with the addition of H2O2 in this concentration range. This small pH dependence with respect to H2O2 may be due to the simultaneous H+ consumption in the valence band and production in the conduction band 20.
Persulfate ion
The initial pH lowered respectively to 6.7 and 5.7 with the persulfate addition. The gradual and continuous increase of the rate constant is attributed to the reaction of this oxidant with a photogenerated electron, producing a strong oxidant, such as sulfate anion radical. This anion radical produces hydroxyl radical when it reacts with H2O and in subsequent step the molecular oxygen decreasing the medium pH.
Chlorate ion
The addition of this oxidant enhanced the initial pH respectively to 7.4 and 6.0. In contrast to the persulfate case, the rate constant enhancement through the chlorate addition can be attributed to the formation of oxidizing species such as ClO2• radical, that reacts with the azo dye, RH, to produce a radical
Comparison of the irradiation times of the DR23 decolorization in the presence of oxidants
Persulfate ion showed the highest efficiency, because 2.5x10-4 mol/L decolorized 97.3 % azo dye in 1 min, followed by chlorate ion using 5.0x10-3 mol/L and 95.7 % also in 1 min and, 97.8 % in 4 h through the addition of 5.0x10-3 mol/L hydrogen peroxide. In the absence of any oxidant 98.6% was decolorized after 6 h irradiation and resulting in a rate constant of 5.59x10-3 min-1. This behavior may be justified in terms of the pH variation during 3 h irradiation as well as the hydroxyl radical production, as it was the case of the hydrogen peroxide and persulfate ion, or of the reduction potential of several oxidant species, as it occurred with the chlorate ion.
Effect of radiation source
When the reaction was performed in the presence of TiO2, the decolorization rate constant increased more than double under solar radiation (15.65x10-3 min-1) relative to the value under artificial conditions (5.59x10-3 min-1). On the other hand, the rate constant was enhanced by about 30% under solar radiation (0.54x10-3 min-1) relative to artificial light (0.41x10-3 min-1) in the absence of TiO2.
The rate constant to solar radiation was 0.54 x 10^-3 min-1 and to artificial light was 0.41 x 10^-3 min-1. the degradation was faster under solar illumination when compared to the artificial one.
Applicant's summary and conclusion
- Conclusions:
- Direct red 23 azo dye was simultaneously decolorized and degraded in 6 h of artificial irradiation in the presence of titanium dioxide following the 1st order kinetic behavior. Seven chemical species were determined during the DR23 degradation. The addition of oxidants such as persulfate ion, chlorate ion and hydrogen peroxide enhanced the rate constants. Concentrations equivalent to 2.5x10-4 mol L-1 persulfate ion and 5.0x10-3 mol L-1 chlorate showed that the persulfate ion decolorized the dye more rapidly than the others. In addition, the degradation was faster under solar illumination when compared to the artificial one.
- Executive summary:
The photocatalytic degradation of aqueous solution of commercial azo textile dye, direct red 23 (DR23), was carried out in TiO2 suspension at 30ºC with the use of artificial and solar light sources. The photoreaction followed the first-order behavior with respect to the azo dye as a function of irradiation time. A 23 factorial design was carried out, in order to obtain the best experimental conditions, using the rate constant of DR23 degradation as the analytical response. Seven chemical species were determined from the normalized UV-Vis spectra during the DR23 degradation through Imbrie Q mode factor analysis followed by varimax and Imbrie oblique rotations. The addition of electron acceptors, such as H2O2, S2O82-, and ClO3- on the optimized conditions, was carried out to increase the DR23 degradation rate. Comparison of degradation efficiencies under artificial and solar radiation was examined in the presence of oxidants.
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