Degradation of Trypan Blue in wastewater by sunlight-assisted modified photo-Fenton reaction
TL;DR: In this article, the degradation of an azo dye (Trypan Blue) by solar photo-Fenton process has been investigated in a batch reactor under sunlight using a neutral pH to modify the same.
Abstract: Homogeneous Fenton reaction (Fe2+/H2O2) is one of the most important advanced oxidation processes to generate free radicals for degradation of organic pollutants in wastewater. Degradation of an azo dye (Trypan Blue) by solar photo-Fenton process has been investigated in this work using a batch reactor under sunlight. Instead of acidic pH used in conventional Fenton reaction, neutral pH is used here to modify the same. Effects of the changes in process parameters, including dosage of ferrous sulphate and hydrogen peroxide as well as pH have been examined. Percent degradation was observed to increase with increasing H2O2 dosing up to a particular critical value. Increase in FeSO4 dose and acidic medium increased degradation. Complete decolourization was achieved after 2 h when 500 mL of 5.2 × 10−4 mol L−1 dye aqueous solution at pH 7 was oxidized with 2.8 × 10−4 mol L−1 of ferrous sulphate and 0.03 mol L−1 of H2O2 under sunlight of average intensity 281 W m−2. Mineralization of dye pollutant was mo...
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TL;DR: Toxicity studies with a plant bioassay and acute tests indicated that the PUF-immobilized microbial consortium favors detoxification of the dye and textile effluents.
Abstract: A microbial consortium that is able to grow in wheat bran (WB) medium and decolorize the carcinogenic azo dye Congo red (CR) was developed. The microbial consortium was immobilized on polyurethane foam (PUF). Batch studies with the PUF-immobilized microbial consortium showed complete removal of CR dye (100 mg·L−1) within 12 h at pH 7.5 and temperature 30 ± 0.2 °C under microaerophilic conditions. Additionally, 92% American Dye Manufactureing Institute (ADMI) removal for real textile effluent (RTE, 50%) was also observed within 20 h under the same conditions. An upflow column reactor containing PUF-immobilized microbial consortium achieved 99% CR dye (100 mg·L−1) and 92% ADMI removal of RTE (50%) at 35 and 20 mL·h−l flow rates, respectively. Consequent reduction in TOC (83 and 79%), COD (85 and 83%) and BOD (79 and 78%) of CR dye and RTE were also observed, which suggested mineralization. The decolorization process was traced to be enzymatic as treated samples showed significant induction of oxidoreductive enzymes. The proposed biodegradation pathway of the dye revealed the formation of lower molecular weight compounds. Toxicity studies with a plant bioassay and acute tests indicated that the PUF-immobilized microbial consortium favors detoxification of the dye and textile effluents.
107 citations
Cites methods from "Degradation of Trypan Blue in waste..."
...Various physicochemical methods can be used to remove dyes from wastewaters such as photocatalysis, ozonation, membrane separation, electrochemical oxidation, activated carbon adsorption, coagulation and Fenton reagent oxidizer [2,11,12]....
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TL;DR: The biodegradation and detoxification of azo dye - Direct Black G (DBG) with a newly isolated thermophilic microflora with a new degradation pathway of DBG degradation by thismicroflora was proposed based on the intermediates identified by LC-ESI-MS/MS.
Abstract: The biodegradation and detoxification of azo dye – Direct Black G (DBG) with a newly isolated thermophilic microflora was investigated in the present study. It was found this microflora can decolorize DBG at a wide range of pH from 5 to 10, and grow well under high concentration of dye (600 mg·L−1) and salinity (50 g·L−1). Its decolorization ratio could reach 97% with 8 h of incubation at optimal conditions. The induction of laccase, manganese peroxidase, lignin peroxidase and azoreductase suggests their synergetic involvements in the degradation process of DBG. In addition, the phytotoxicity analysis indicated the thermophilic microflora converted toxic dye DBG into low toxicity metabolites. PCR-DGGE analysis revealed that there are nine different bacteria presented in this microflora. Furthermore, a new degradation pathway of DBG degradation by this microflora was proposed based on the intermediates identified by LC-ESI-MS/MS.
91 citations
TL;DR: An overview on photolytic as well as homogenous and heterogeneous photocatalytic degradation methods with the use of various catalysts is presented andsembling of MS/MS spectra libraries of drug molecules and their phototransformation products was identified as the future challenge.
Abstract: Consumption of psychotropic drugs is still increasing, especially in high-income countries. One of the most crucial consequences of this fact is significant release of them to the environment. Considerable amounts of atypical antipsychotics, benzodiazepines, antidepressants, and their metabolites were detected in river, lake, and sea water, as well as in tissues of aquatic organisms. Their ecotoxicity was proved by numerous studies. It should be noticed that interaction between psychotropic pharmaceuticals and radiation may lead to formation of potentially more toxic intermediates. On the other hand, photo-assisted wastewater treatment methods can be used as an efficient way to eliminate them from the environment. Many methods based on photolysis and photocatalysis were proposed and developed recently; nevertheless, the problem is still unsolved. However, according to recent studies, photocatalysis could be considered as the most promising and far more effective than regular photolysis. An overview on photolytic as well as homogenous and heterogeneous photocatalytic degradation methods with the use of various catalysts is presented. The photostability and phototoxicity of pharmaceuticals were also discussed. Various analytical methods were used for the photodegradation research, and this issue was also compared and summarized. Use of high-resolution multistage mass spectrometry (Q-TOF, ion trap, Orbitrap) was suggested. The combined techniques such as LC–MS, GC–MS, and LC–NMR, which enable qualitative and quantitative analyses in one run, proved to be the most valuable in this case. Assembling of MS/MS spectra libraries of drug molecules and their phototransformation products was identified as the future challenge.
85 citations
Cites background from "Degradation of Trypan Blue in waste..."
...Coagulation or precipitation of Fe3+ ions did not occur because of low concentration of FeSO4 (Dutta et al. 2015)....
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TL;DR: Experimental evidence is provided for the utilization of agricultural waste as a novel low-cost growth medium for biodegradation of benzidine-based dyes and the potential of the microbial consortium in detoxification is suggested.
Abstract: Environmental release of benzidine-based dyes is a matter of health concern. Here, a microbial consortium was enriched from textile dye contaminated soils and investigated for biodegradation of the carcinogenic benzidine-based dye Trypan Blue using wheat bran (WB) as growth medium. The PCR-DGGE analysis of enriched microbial consortium revealed the presence of 15 different bacteria. Decolorization studies suggested that the microbial consortium has high metabolic activity towards Trypan Blue as complete removal of 50 mg∙L−1 dye was observed within 24 h at 30 ± 0.2 °C and pH 7. Significant reduction in TOC (64%) and COD (88%) of dye decolorized broths confirmed mineralization. Induction in azoreductase (500%), NADH-DCIP reductase (264%) and laccase (275%) proved enzymatic decolorization of dye. HPLC analysis of dye decolorized products showed the formation of six metabolites while the FTIR spectrum indicated removal of diazo bonds at 1612.30 and 1581.34 cm−1. The proposed dye degradation pathway based on GC-MS and enzyme analysis suggested the formation of two low molecular weight intermediates. Phytotoxicity and acute toxicity studies revealed the less toxic nature of the dye degradation products. These results provide experimental evidence for the utilization of agricultural waste as a novel low-cost growth medium for biodegradation of benzidine-based dyes, and suggested the potential of the microbial consortium in detoxification.
41 citations
Cites methods from "Degradation of Trypan Blue in waste..."
...The COD removal by the microbial consortium was significant compared to solar energy-assisted photo-Fenton oxidation of Trypan Blue [14], which achieved a COD removal of 51....
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TL;DR: The self-modification of ZrO2 for enhanced the degradation of organic pollutants is reviewed, including the type of synthetic route and synthesis parameter variation, and some challenges with ZRO2 catalysts are discussed to promote new ideas to improve photocatalytic performance.
Abstract: Over the past few years, photocatalysis is one of the most promising approaches for removing organic pollutants. Zirconium dioxide (ZrO2) has been shown to be effective in the photodegradation of organic pollutants. However, low photoresponse and fast electron-hole recombination of ZrO2 affected the efficiency of catalytic performance. Modifying the photocatalyst itself (self-modification) is a prominent way to enhance the photoactivity of ZrO2. Moreover, as ZrO2-like photocatalysts have a large bandgap, improving the spectral response via self-modification could extend the visible light region and reduce the chance of recombination. Here, we review the self-modification of ZrO2 for enhanced the degradation of organic pollutants. The approaches of the ZrO2 self-modification, including the type of synthetic route and synthesis parameter variation, are discussed in the review. This will be followed by a brief section on the effect of ZrO2 self-modification in terms of morphology, crystal structure, and surface defects for enhanced photodegradation efficiency. It also covers the discussion on the photocatalytic mechanism of ZrO2 self-modification. Finally, some challenges with ZrO2 catalysts are also discussed to promote new ideas to improve photocatalytic performance.
27 citations
References
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Book•
01 Jan 1992
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!
78,324 citations
TL;DR: In this article, the optimal conditions for reactive black 5 (RB5) decolorization were investigated using Fenton and photo-Fenton processes, with a little difference between the two processes, 97.5% and 98.1%, respectively.
Abstract: The oxidative decolorization of Reactive Black 5 (RB5) in aqueous solution has been studied using Fenton (H 2 O 2 /Fe 2+ ) and photo-Fenton (H 2 O 2 /Fe 2+ /UV) processes. This investigation reveals that both methods can remove the color of RB5. Batch experiments were carried out to investigate the process's optimal operational conditions: pH, H 2 O 2 dosage, Fe 2+ dosage, RB5 concentration and optimal [Fe 2+ ] 0 /[H 2 O 2 ] 0 /[RB5] 0 ratio, to obtain the bests results at low cost, render AOP competitive with other processes. The optimal conditions found were a ratio [H 2 O 2 ] 0 /[RB5] 0 of 4.9:1, a ratio [H 2 O 2 ] 0 /[Fe 2+ ] 0 of 9.6:1 and pH = 3.0. The decolorization experiments indicate that RB5 can be effectively decolorized using Fenton and photo-Fenton processes with a little difference between the two processes, 97.5% and 98.1%, respectively, for optimal conditions. This small difference in dye decolorization is not similar to TOC removal: with photo-Fenton process there is a significant increment (46.4% TOC removal) relatively to Fenton process (only 21.6% TOC removal). This fact indicates that although UV low-pressure mercury lamp has little effect on dye decolorization it is particularly important in dye mineralization.
731 citations
"Degradation of Trypan Blue in waste..." refers background in this paper
...Advanced oxidation processes (AOP) generate the second most powerful oxidant, that is OH free radical to oxidize the organic pollutants ultimately to carbon dioxide and water [3,4]....
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...However, these methods merely transfer dyes from the liquid to the solid phase causing secondary pollution and requires further treatment [3]....
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TL;DR: In this article, simulated dye wastewater, separately prepared with disperse, reactive, direct, acid and basic dyes, were decolorized with a hydrogen peroxide-ferrous ion system, known as Fenton's reagent.
Abstract: Five types of simulated dye wastewater, separately prepared with disperse, reactive, direct, acid and basic dyes, were decolorized with a hydrogen peroxide-ferrous ion system, known as Fenton's reagent. The results are that the best pH value for decolorization is below 3.5, the average percent removal of chemical oxygen demand (COD) is about 90%, the transparency of wastewater is above 25 cm and the average percent decolorization is above 97%. All the results of treating the dye wastewater of actual dyeing and finishing mills are similar to those in the laboratory. Temperature mainly influences the speed of decolorization, i.e. the lower the temperature, the longer the time for decolorization.
668 citations
"Degradation of Trypan Blue in waste..." refers background in this paper
...Fenton reaction with Fe and H2O2 is one such AOP [1,9–13] that can be further enhanced with the help of visible or UV light [14]....
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TL;DR: A review of the widely used and most promising industrial wastewater decolourization methods is presented in this paper, where a critical review is made on the various treatment methodologies and emerging technologies with a note on their advantages and disadvantages.
Abstract: Water pollution control is presently one of the major thrust areas of scientific research. While coloured organic compounds generally impart only a minor fraction of the organic load to wastewaters, their colour renders them aesthetically unacceptable. Stringent regulating measures are coaxing industries to treat their waste effluents to increasingly high standards. Colour removal, in particular, has recently become an area of major scientific interest as indicated by the multitude of related research reports. During the past two decades, several decolourization techniques have been reported, few of which have been accepted by some industries. There is a need to find alternative treatments that are effective in removing dyes and colourants from large volume of effluents, which are cost-effective, like the biological or integrated systems. This article reviews some of the widely used and most promising industrial wastewater decolourization methods. Data on decolourizing efficiencies of different causative agents, obtained by means of different physical, chemical and biological methods are discussed. Further a critical review is made on the various treatment methodologies and emerging technologies with a note on their advantages and disadvantages.
617 citations
"Degradation of Trypan Blue in waste..." refers background in this paper
...Reviews on Fenton and photo-Fenton reactions also elucidated degradation of compounds other than dyes [19,20]....
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TL;DR: The potential of advanced chemical oxidation for future hazardous wastes treatment is demonstrated by four AOP systems, namely, H2O2/Fe2+, TiO 2/uv/O2, H 2O22, and TiO2-uv/H2O 2, exemplified by chlorophenols.
Abstract: Chemical oxidation reactions involving hydroxyl radicals have been extremely effective in the destruction of organic pollutants. These advanced chemical oxidation processes (AOP) generally use a combination of oxidation agents (such as H2O2 or O3), irradiation (such as uv or ultrasound), and catalysts (such as metal ions or photocatalysts) as a means to generate hydroxyl radical. The hydroxyl radical is one of the strongest inorganic oxidants next to elemental fluorine. The hydroxyl radical is stable over a wide pH range, up to pH 10. The hydroxyl radical reacts with organic by three major mechanisms: hydroxy addition, hydrogen abstraction, and electron transfer. Several AOP systems are reviewed first. The merits as well as limitations of these systems are discussed. The potential of AOP for future hazardous wastes treatment is then demonstrated by four AOP systems, H2O2/Fe2+, TiO2/uv/O2, H2O2, and TiO2/uv/H2O2, exemplifiedby chlorophenols. A reaction scheme can be generalized for the oxidation of halogenated phenols by advanced chemical oxidation, specifically, ones involving hydroxyl radicals. Upon the attack of a halogenated phenol, ArXnOH, by a hydroxyl radical, OH·, a free radical, Ar(OH)2Xn·, is formed. This free radical can undergo two reaction paths: (1)hydroxylation without dechlorination (Type A) and (2) hydroxylation with dechlorination (Type B). It has been observed that mono-halogenated phenols (n=1) only follow Type A path: dichlorophenols (n=2) and trichlorophenols (n=3) can have both Type A and Type B reaction pathways; tetrahalogenated (n=4) and pentahalogenated (n=5) phenols only follow Type B reaction pathway.
519 citations
"Degradation of Trypan Blue in waste..." refers background in this paper
...Fenton reaction with Fe and H2O2 is one such AOP [1,9–13] that can be further enhanced with the help of visible or UV light [14]....
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