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phototransformation in water
Type of information:
experimental study
Adequacy of study:
weight of evidence
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Results have been reported in a pubblication

Data source

Reference Type:

Materials and methods

Study type:
indirect photolysis
Principles of method if other than guideline:
Fenton's Reagent reaction
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrasodium 7-[[2-[(aminocarbonyl)amino]-4-[[4-chloro-6-[[3-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]amino]-1,3,5-triazin-2-yl]amino]phenyl]azo]naphthalene-1,3,6-trisulphonate
EC Number:
EC Name:
Tetrasodium 7-[[2-[(aminocarbonyl)amino]-4-[[4-chloro-6-[[3-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]amino]-1,3,5-triazin-2-yl]amino]phenyl]azo]naphthalene-1,3,6-trisulphonate
Cas Number:
Molecular formula:
tetrasodium 7-[[2-[(aminocarbonyl)amino]-4-[[4-chloro-6-[[3-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]amino]-1,3,5-triazin-2-yl]amino]phenyl]azo]naphthalene-1,3,6-trisulphonate
Test material form:
solid: particulate/powder

Study design

Analytical method:
other: UV-VIS
Light source:
other: artifical lamp
Details on light source:
500 - 2000 Lx
Details on test conditions:
pH of each reaction solution was adjusted to desired value by using 1M sodium hydroxide and 1M sulphuric acid and was measured by pH meter.Magnetic stirrer provided continuous and uniform shaking.Temperature control was realized through hot plate.

Results and discussion

Details on results:
Optimization of dye concentration and determination of ʎ max:absorbance increased with increase in concentration of dye solution. So, ʎ max of the test substance was 422 nm and optimized concentration was 0.005 % for conducting experiments;Effect of pH on decolourization of dye: the effect of initial pH on the decolourization by Fenton oxidation process was studied in pH range of 2.5 - 6.0.Effect of pH from 2.5 to 6.0 on treatment efficiency was very dramatic. Decolourization of dye was 68 % after 1h at pH 2.5.Further increase in pH from 2.5 to 3.0 caused surprising increase in % age colour removed from 68 to 96 % after 1 h. At pH 2.5 decolourization efficiency decreased. Further increase in pH from 3.0 to 6.0 decreased decolourization rates. The difference in decolourization efficiencies is due to variation in hydrogen peroxide decomposition to •OH radicals. Increase in pH from 3.0 to 6.0 caused decrease in % age colour removal from 96 to 8.39 %. Increase in pH from 3 to 6, caused decreased in colour removal from 96 to 8.39 %. It is because iron starts to precipitate as hydroxide.Additionally, the oxidation potential of hydroxyl radicals was known to decrease with increasing pH.Effect of on decolourization of dye: H2O2plays an important role as a source of •OH generation in Fenton reaction.Increasing concentration from 0.001 to 0.005 M % age decolourization increased from 42.8 to 95.8 % after 1 h.94.9 % colour removal was observed with 0.005M H2O2after 0.5 h while using 0.01M H2O273 % colour removal was observed after half hour.Whereas at the end of experiment % age colour removal of 96 % was observed by using 0.01M H2O2.Further increase in H2O2concentration from 0.01 to 0.02 M caused decrease in % age colour removal from 96 to 81 % after 1 h.Same result was observed while using 0.04M H2O2, which gave 50.4 % colour removal at end of 1 h.So optimal hydrogen peroxide concentration in Fenton oxidation of dye is 0.005 M, which caused 94.9 % age colour removal after 0.5 h.Effect of FeSO4 dosage on decolourization:decolourization was limited at 0.5 × 10-5 M and only 55.22 % of dye was degraded within 1 h of reaction.In presence of 1.5 × 10-5 M, 2.5 × 10-5 M and 3.5 × 10-5 M of Fe2+, a great improvement of decolourization efficiencies within 1 h of reaction achieved were 89.6, 92.73 and 95.6 %, respectively.So increase in concentration of FeSO4from 3.5 × 10-5 M caused decrease from 95.6 to 85.22 % at end of one hour. So optimum concentration of FeSO4required for decolourization of dye is 3.5 × 10-5 M.Effect of temperature on decolourization:the effect of temperature on decolourization of dye was studied at different temperatures 30, 40, 50 and 60 ºC.The decolourization efficiency within 20 min of reaction increased from 24.64 to 80.22 % as increasing the temperature from 30 to 50 ºC.Additionally, the period of time required for decolourization of dye was much shorter at higher temperature.Degradation rate decreased when temperature was 60 ºC due to decomposition of H2O2at higher temperature.Degradation efficiency decreased from 80.22 to 71.70 % within 20 min by increasing the temperature from 50 to 60 ºC so optimum temperature required for decolourization of dye is 50 ºC.Effect of artificial light intensity on decolourization:effect of artificial light intensity on decolourization of dye yellow dye by photo-Fenton process was investigated by varying the light intensity from 500 Lx to 2000 Lx.Decolourization efficiency of yellow dye increased by increasing the intensity of light.Maximum decolourization was achieved by using 2,000 Lx light which removed 98.78 % colour. 93.90 % colour removal was achieved by using 2.000 Lx light within 10 minutes only. So optimum light intensity was 2,000 Lx.Effect of salts:in absence of salts, the dye decolourization was 99.42 %. Addition of NaCl and Na2CO3 to dye solution caused only 4 and 3 % decrease in decolourization percentage.Chemical Oxidation Demand (COD):the experiments of Fenton and photo- Fenton processes showed 52.27 and 38.63 % reduction of COD. It appears that photo-Fenton process is more beneficial for degradation as obvious from COD removal.

Applicant's summary and conclusion

Fenton and photo-Fenton processes are powerful methods for decolourization of dye, but photo-Fenton process is more efficient. The optimum conditions in both processes were observed at pH = 3, with Fe2+ concentration of 3.5 × 10-5 M and H2O2 concentration 0.005 M with dye concentration of 0.005 %.
Executive summary:

The degradation of the dye by Fenton and photo-Fenton processes was investigated. Among advanced oxidation processes, oxidation using Fenton's reagent is an attractive treatment for the effective decolourization and degradation of dye because of its low cost and the lack of toxicity of the reagents.

The degradation rate was strongly dependent on pH, initial concentrations of Fe2+,H2O2, temperature and light intensity. The effects of these parameters have been studied and optimum operational conditions of these two processes were found. The optimum conditions were found at pH 3 for these processes. The decolourization experiments indicate that dye can be effectively decolourized using Fenton and photo-Fenton processes with a little difference between the two processes, 91.4 and 97.8 % within 0.5 h, respectively for optimal conditions. The difference in decolourization is not similar to COD removal: with Fenton process there is significant increment (52.27 % COD removal) relatively to photo-Fenton process (only 38.63 % COD removal).