Homogeneous photodegradation of dye aqueous solution with H 2 O 2 /UV process: The effects of inorganic anions and temperature Environmental Science Environmental Science (original) (raw)
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Photodegradation of aqueous solution of Mordant red17 (MR17) azo dye in UV/H 2 O 2 , advanced oxidation process was investigated in this study. Results show that MR17 dye decolorization rate was mainly effected by different parameters such as solution pH, H 2 O 2 concentration, initial dye concentrations and presence of different inorganic anions such as NO 3 -, Cl -, CO 3 2ions. The degradation percent of the dye decreased by the presence of inorganic anions in the order of CO 3 2-> Cl -> NO 3 ions. While increase the temperature of the solution medium from 283 to 318K led to increase the decolorization rate of MR17 dye from 0.048 to 0.164 min -1 . The low value of the apparent activation energy E a (24.91 kJ mol -1 ) indicates that decolorization process of MR17 dye is achieved easily using H 2 O 2 /UV process. This results further proved by presence of 100% decolorization of MR17 dye in about 50 min and about 85.57% mineralization in a 3.0 h photoperiod.
Enhancement of photodegradation of mordant dyes by iron powder and H2O2 in presence of UV light
In this study different treatment methods such as H 2 O 2 /UV, Fenton and photo-Fenton (Fe +n /H 2 O 2 /UV) treatments, have been used to investigate the removal of the Mordant red 7 (MR7) azo dye from aqueous solution. In photo-Fenton treatment, iron (Fe) powder was used as a cheap source of Fe 2+ ions. Complete decolorization of MR7 using H 2 O 2 /UV process, achieved in less than 60 min. The photodegradation process was mainly effected by different parameters such as initial dye concentrations, [H 2 O 2 ], pH value and presence of different inorganic salts such as carbonate, nitrate and chloride ions. The decrease in the degradation percent was in the order of Carbonate > chloride > nitrate ions. In comparison, the photo-Fenton treatment, using Fe powder as a source of Fe 2+ ions, was more efficient in the decolorization of MR7. It was found that complete decolorization of MR 7 obtained in about 30 min. Furthermore, mineralization of MR 7 was investigated using chemical oxygen demand (COD) experiment. The results indicated that, 66.67% of the MR7 dye was mineralized using H 2 O 2 /UV process in a 3.0 h photoperiod. While photo-Fenton treatment (in presence of Fe 0 powder), was more efficient and resulted in complete mineralization of MR7 dye in about 2.0 h of photoperiod.
Decolorization of Mordant red 73 azo dye in water using H2O2/UV and photo-Fenton treatment
Decolorization of the Mordant red 73 (MR73) azo dye in water was investigated in laboratory-scale experiments using UV/H 2 O 2 and photo-Fenton treatments. Photodegradation experiments were carried out in a stirred batch photoreactor equipped with a low-pressure mercury lamp as UV source at 254 nm. The effect of operating parameters such as pH, [H 2 O 2 ] , [dye] and the presence of inorganic salts (NaNO 3 , NaCl and Na 2 CO 3 ) were also investigated. The results indicated that complete dye decolorization was obtained in less than 60 min under optimum conditions. Furthermore, results showed that dye degradation was dependent upon pH, [H 2 O 2 ] and initial dye concentration. The presence of chloride ion led to large decreases in the photodegradation rate of MR73 while both nitrate and carbonate ions have a slight effect. The photo-Fenton treatment, in the presence of Fe powder as a source of Fe 2+ ions, was highly efficient and resulted in 99% decolorization of the dye in 15 min. Mineralization of MR73 dye was investigated by determining chemical oxygen demand (COD). In a 3 h photoperiod "65%" of the dye was mineralized by the H 2 O 2 /UV process, while the photo-Fenton treatment was more efficient producing 85% mineralization over the same 3-h period.
2019
The degradation of Reactive Red-180 dye and dye effluent containing Reactive Red-180 dye was investigated using H2O2 solar assisted photodegradation process (H2O2/Solar Light). The photodegradation process was carried out in 250 ml conical flasks with side arms with a dye solution with concentration of 100 mg/l with 50% H2O2 irradiated with sun light in the lux intensity range of 60,00090,000 lux.100% decolourisation was achieved in both RR-180 dye and 75% diluted effluent containing RR180 whereas 96.18% decolourisation was achieved for undiluted effluent containing RR-180 under optimum reaction conditions. An optimum pH of 7 with H2O2 concentration of 700 mM is required for complete decolourisation of both RR-180 dye and effluent containing RR-180. Therefore H2O2/ Solar light is proved to be a more appropriate method for decolourisation of the azo dye Reactive Red-180.
Decolorization of textile azo dye reactive orange 16 with UV/H2O2 process
Journal of the Serbian Chemical Society, 2012
The photochemical decolorization of C.I. Reactive Orange 16 (RO16), a reactive textile azo dye, by the UV/H 2 O 2 process was studied using a batch photoreactor with UV lamps emitting at 253.7 nm. Complete decolorization of 50.0 mg dm -3 initial dye concentration was achieved in less than 6 min under optimal conditions (25 mM initial peroxide concentration, at pH 7.0 and with a UV light intensity of 1950 μW cm -2 ). The effects of experimental variables, such as initial pH, initial concentration of H 2 O 2 , initial dye concentration, and the intensity of UV light were studied. The highest decolorization rates were realized at a peroxide concentration in range from 20 to 40 mM, above which decolorization was inhibited by the scavenging effect of the peroxide. The decolorization was more efficient in neutral pH values. The efficiency of the process was improved with lower initial dye concentrations and at higher intensities of UV light.
Dyes and Pigments, 2002
The photodegradation of three non hydrolysed reactive azo dyes (Reactive red 120, Reactive black 5, Reactive yellow 84) in aqueous solution was investigated in a laboratory-scale batch photoreactor equipped with an immersed lowpressure mercury lamp. Six different doses of hydrogen peroxide, at constant initial concentration of the substrate (100 mg/l) were used. The pseudo-first order rate constants have been calculated from the experimental kinetic curves, for the three azo dyes. These rate constants have extreme values of the order of 0.1 min À1 at a H 2 O 2 dose of 24.5 mmol/l. The effectiveness of the UV/H 2 O 2 process has been evaluated by the degree mineralization of the total organic carbon (TOC), as a complementary indicator of the treatment efficiencies. Our results confirm the suitability of the UV/H 2 O 2 process as a textile wastewater pre-treatment step, once optimum operating conditions and cost effectiveness of the method are established. #
Decolorization and Mineralization of Cationic Dye (Crystal Violet) by Several Photochemical Methods
2015
The aim of this study is to test the ability of some photochemical processes advanced oxidation processes (AOPs) such as: UV/H2O2, UV/S2O8 2to eliminate dye in aqueous solution. The efficiency of substrate decolorization and mineralization in each process has been comparatively discussed by decreases in concentration and total chemical oxygen demand content of CV solutions. The obtained results showed that system like: H2O2/UV and S2O8 2/UV were better than direct UV photolysis at.254 nm and acetone/UV at the same wavelength. This improvement seems to be linked to production of OH • and SO4 •radicals issued from the photolysis of H2O2 and S2O8 2, always at this same wavelength. The most efficient method on decolorization and mineralization was observed to be UV/H2O2 process. Mineralization efficiency was observed in the order of UV/H2O2> UV/S2O8 2 . Final solutions of AOPs applications after treatment can be disposed safely to environment. The degradation rate is strongly depende...
Al-Nahrain Journal for Engineering Sciences
In this study sunlight and UV radiation were used to compare the efficiency of decolorization of textile wastewater containing brilliant reactive red dye K-2BP (λmax = 534 nm) by the advanced oxidation process (AOP) using (H2O2/sunlight, H2O2/UV, H2O2/TiO2/sunlight, and H2O2/TiO2/UV). The results studied the effect of solution pH, applied H2O2 concentration, TiO2 concentration (nanoparticle), and initial dye concentration were studied. The experimental results showed that decolorization percentage with H2O2/sunlight and TiO2/H2O2/sunlight under the following conditions: - reaction time 150 of minutes, [ 500 ppm] H2O2, [100 ppm] TiO2, pH=3, initial dye concentration =15 ppm and at ambient temperature were 95.7% and 98.42% respectively. For the same conditions using H2O2/UV, H2O2/TiO2 /UV, the percentage of decolorization were 97.85% and 96.33% respectively. The results also indicated that the sunlight is more economic and cost-effective than UV radiation.
The effect of anions on decolorization of textile azo dye Reactive Orange 16 with UV/H2O2 process
Advanced Technologies, 2019
The effects of various organic and inorganic anions on decolorization of textile dye Reactive Orange 16 by means of hydroxyl radicals have been studied. These anions are commonly present in wastewaters from textile industry and include chloride, sulfate, carbonate/bicarbonate, nitrate and acetate anions. The experiments were conducted in the presence of different concentrations of anions and at different initial pH values in a batch photoreactor equipped with UV-C (254 nm) lamps in the presence of hydrogen peroxide. It was obtained that decolorization efficiency was significantly affected by nature and concentration of the investigated anions. An inhibitory effect of acetate anions increased with increasing in their concentration and depended on whether protonated or deprotonated forms are favored. Carbonate anion showed specific, both positive and negative influence, depending on its concentration. Influence of bicarbonate, nitrate and chloride was more prominent at their higher initial concentrations. The presence of sulfate did not have noticeable impact on decolorization of RO16 dye under investigated conditions.
The photodecolourisation of textile dye Reactive Blue 19 (RB 19), an anionic anthraquinone dye of the reactive class, was investigated using UV radiation in the presence of H2O2 in a batch photo-reactor with low-pressure mercury lamps. The effects of the system parameters: initial pH, initial dye concentration, concentration of peroxide and radiation intensity, as well as the presence of salts, (NaCl, Na2SO4, NaNO3, NaH2PO4) on dye decolourisation was examined. Increasing the initial pH resulted in an increase in decolourisation efficiency. Results showed that with an increase of dye concentration from 10 to 100 mg∙ℓ–1, the efficiency of the process decreases. The highest decolourisation rates were noted at H2O2 concentrations of approximately 30 mmol∙ℓ–1. The increase of radiation intensity from 730 to 1 950 μW∙cm–2, linearly increases decolourisation efficiency. The inorganic ions investigated have inhibiting effects on RB 19 decolourisation by the UV/H2O2 process with inhibition intensities in the following order: H2PO4– > NO3– > SO42– > Cl–. This study has shown that the UV/H2O2 process is a promising technology for degradation of RB 19 in water and wastewater.