Fenton-enhanced γ-radiolysis of cyanuric acid

Varghese, Rani; Aravind, Usha K.; Aravindakumar, Charuvila T.

doi:10.1016/j.jhazmat.2006.08.010

Cited by 13 publications

(4 citation statements)

References 16 publications

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“…17 The Fenton-enhanced γ-radiolytic process caused ∼80% mineralization of cyanuric acid. 18 To the extent that photoassisted TiO 2 oxidation processes have proven ineffective in degrading cyanuric acid, alternative metal chalcogenide (e.g., ZnO) photomediators could act as process photosensitizers owing to the photogeneration of electron-hole pairs in such mediators that induce redox reactions with adsorbates on the metal chalcogenide surface. Zinc oxide displays interesting photoactivity, sometimes greater than TiO 2 , 19 despite its relatively large band gap (3.2 eV) and its photoinstability toward corrosion releasing Zn 2+ ions into the aqueous media.…”

Section: Introductionmentioning

confidence: 99%

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Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

et al. 2007

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The photoassisted oxidative transformation of the highly recalcitrant cyanuric acid was examined in the liquidsolid regime at pH 3 and natural pH 7.5 under UV irradiation in oxygen-and ozone-saturated ZnO suspensions using ZnO as a photomediator. Loss of cyanuric acid was assayed by HPLC UV absorption spectroscopy, whereas intermediates and final products were determined by HPLC ion chromatography (IC), by MS techniques using an electrospray ionization mass spectrometer operated in the negative-ion mode, and by FT-IR spectroscopy. Final reaction products were CO 2 gas and NO 3 -ions. The measure of nitrate in solution quantified the degree of mineralization of the substrate; its concentration in solution was lower than indicated by the loss of cyanuric acid owing to adsorption of the latter to the ZnO surface. Some degree of corrosion of ZnO occurred as evidenced by the quantity of Zn 2+ present in acidic and near-neutral aqueous media before and during the photoassisted process. The possible site(s) and mode(s) of adsorption of cyanuric acid on ZnO have been inferred from theoretical calculations of point charges; the position(s) of attack of the substrate by • OH radicals was inferred from frontier electron density calculations. Mechanistic considerations are based on the possible involvement of Zn 2+ -cyanurate species (chemisorbed cyanuric acid) in the degradation of such a recalcitrant substrate, inasmuch as the use of TiO 2 -photoassisted processes under similar conditions have so far failed to oxidize cyanuric acid.

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Section: Introductionmentioning

confidence: 99%

“…Biologically based cyanuric acid treatment with bacteria leads to complete substrate mineralization through formation of biuret and urea intermediates . The Fenton-enhanced γ-radiolytic process caused ∼80% mineralization of cyanuric acid …”

Section: Introductionmentioning

confidence: 99%

Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

et al. 2007

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“…For the further treatment of cyanuric acid, conventional water treatment processes such as precipitation/adsorption may not be efficient due to the lower level in water. Nevertheless, some advanced oxidation processes such as UV/ZnO (oxygen-saturated or ozonesaturated) (31), UV/TiO 2 /O 3 with the assistance of H 2 O 2 at pH 12, UV/O 3 /H 2 O 2 at pH 12 (32), sulfate radical (33), and Fentonenhanced radiolysis (34) were suggested for further downgrading of cyanuric acid. This examination of intermediates and end-products has provided valuable information on the feasibility and optimization of the photocatalytic process in terms of the degradation of simazine.…”

Section: Resultsmentioning

confidence: 99%

Removal of Simazine in a UV/TiO₂ Heterogeneous System

Chu

Rao

Wang

2009

J. Agric. Food Chem.

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The degradation of simazine by photocatalytic oxidation in a TiO2 suspension was studied. The influence of various parameters such as wavelength sources, light intensity, TiO2 dosage, and initial pH has been investigated, and the optimum conditions for the degradation of simazine have been identified. The photocatalytic degradation of simazine was observed to follow a pseudo-first-order reaction. The overdose of light intensity and photocatalyst does not always guarantee a beneficial effect on the photocatalytic reaction, and the optimum TiO2 dosage was found to be 0.1 g/L in this study. The optimum pH value is 9.0 for the photocatalytic degradation of simazine, whereas extremely acidic and alkaline conditions inhibit photocatalytic efficiency. Simazine can be fully destroyed, but ring-opening and mineralization are not observed in this system. In addition, seven simazine derivatives (CEAT, OEET, CAAT, ODET, OEAT, OAAT, OOOT) were detected by LC-ESI/MS. It is suggested that dealkylation is the major pathway of simazine photodecay in UV/TiO2 systems. The final product was found to be cyanuric acid.

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“…Among them, cyanuric acid (CA) is the most well-known, although it was reported to be degraded under some harsh conditions. [1][2][3] The recalcitration of CA by TiO 2 photocatalytic oxidation and Fenton process has been conrmed by comprehensive experimental studies. [4][5][6] Moreover, although s-triazine and other triazine-based herbicides and dyes undergo rapid degradation under AOP conditions, the degradation always stops at CA as the nal product.…”

Section: Introductionmentioning

confidence: 99%

Recalcitrance of cyanuric acid to oxidative degradation by OH radical: theoretical investigation

Liu

2014

RSC Adv.

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Fenton-enhanced γ-radiolysis of cyanuric acid

Cited by 13 publications

References 16 publications

Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

Removal of Simazine in a UV/TiO₂ Heterogeneous System

Recalcitrance of cyanuric acid to oxidative degradation by OH radical: theoretical investigation

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Fenton-enhanced γ-radiolysis of cyanuric acid

Cited by 13 publications

References 16 publications

Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions

Removal of Simazine in a UV/TiO2 Heterogeneous System

Recalcitrance of cyanuric acid to oxidative degradation by OH radical: theoretical investigation

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Removal of Simazine in a UV/TiO₂ Heterogeneous System