Degradation of Clopyralid by the Fenton Reaction

Westphal, Katharina; Saliger, R.; Jäger, Dennis; Teevs, Linda; Prüße, Ulf

doi:10.1021/ie302769p

Cited by 17 publications

(12 citation statements)

References 30 publications

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“…From chloride evolution in this work, dechlorination of herbicides seems to be the initial mechanism of parent compound abatement. These results are also substantiated in other work …”

Section: Resultssupporting

confidence: 90%

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Photocatalytic ozonation of clopyralid, picloram and triclopyr. Kinetics, toxicity and influence of operational parameters

Solís

Rivas

Gimeno

et al. 2014

J of Chemical Tech & Biotech

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BACKGROUND Photolysis, photocatalysis, ozonation and photocatalytic ozonation in the presence of titania have been applied to the elimination of three pyridine carboxylic acids herbicides (clopyralid, picloram and triclopyr) in water. RESULTS Photocatalytic ozonation led to the best results in terms of herbicide elimination rate and mineralization. The herbicides were relatively recalcitrant to direct ozonation (rate constants: 20 M−1 min−1 for clopyralid and triclopyr, and 105 M−1 min−1 in the case of picloram). Herbicides degradation proceeds by hydroxyl radicals attack (rate constants: 0.73, 3.80 and 1.73 × 109 M−1 s−1 for clopyralid, picloram and triclopyr, respectively). Monitoring of chloride and nitrates suggests dechlorination as the primary stage in the process. Further ring opening led to the accumulation of nitrates and the appearance of some low weight carboxylic acids. Toxicity decreased at the end of the process. CONCLUSION Tested herbicides slowly react with ozone. Photocatalytic ozonation shows different degrees of synergism, leading to 80% mineralization in less than 1 h. Small amounts of TiO2 (i.e. 0.005 g L−1) maintains the efficiency of the photocatalytic ozonation. Quantitative free chloride and nitrates rapidly appear in the O3/UVA/TiO2 system. First intermediates in the photocatalytic ozonation of clopyralid show higher toxicity than the parent compound. © 2014 Society of Chemical Industry

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“…From chloride evolution in this work, dechlorination of herbicides seems to be the initial mechanism of parent compound abatement. These results are also substantiated in other work …”

Section: Resultssupporting

confidence: 90%

“…These results are also substantiated in other work. 14 In addition, nitrate accumulation curves follow the same pattern as TOC conversion indicating that ring opening and pyridinic-nitrogen loss are the key stages in mineralization. Figure 7 shows the maximum nitrate concentration expected in solution from the pyridinic nitrogen.…”

Section: Catalyst Reusementioning

confidence: 83%

Photocatalytic ozonation of clopyralid, picloram and triclopyr. Kinetics, toxicity and influence of operational parameters

Solís

Rivas

Gimeno

et al. 2014

J of Chemical Tech & Biotech

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show abstract

“…Traditional oxidation methods are not efficient to remove complex structures, thus, advanced oxidation processes (AOP) have been applied to degradation of dyes, pigments, pesticides and others organic molecules [3][4][5][6][7]. Fenton reaction process arises as one of the most useful oxidation way because of generation of HO• radicals, which are extremely oxidant [8], they are produced by the interaction between transition metals and H 2 O 2 concerning i.e.…”

Section: Introductionmentioning

confidence: 99%

Stability of Cu species and zeolite structure on ecological heterogeneous Fenton discoloration–degradation of yellow 5 dye: Efficiency on reusable Cu‐Y catalysts

Guzmán‐Vargas¹,

Rosa-Pineda²,

Oliver-Tolentino³

et al. 2015

Env Prog and Sustain Energy

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The discoloration-degradation of yellow 5 dye was achieved through the heterogeneous Fenton reaction using Cu-Y catalysts. Cu-Y materials were prepared by an aqueous ion exchange method from the NH 4 -Y parent zeolite. The solids are characterized by X-ray diffraction, nitrogen physisorption, EPR and,27 Al and 29 Si NMR spectroscopies. Discoloration around 100% with 60% of COD removal was achieved before 90 min at 50 C using the next reaction conditions: 50 mL of colored solution containing 50 ppm of dye, 0.129 mmol of H 2 O 2 , catalyst mass/volume of solution ratio (g L 21 )5 0.016 and pH 5 4-5. The influence of temperature and H 2 O 2 concentration was also studied. The discoloration kinetics were modeled using the pseudo-first order reaction. High catalytic activity was observed even after four reaction cycles, which is credited to the good stability of the Cu species and the zeolite structure. Because the Fenton reaction was favored by the acid media provided by the Cu-Y catalyst and temperature, the addition of any acid was not necessary, avoiding the generation of sludge, resulting in an ecofriendly process.

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“…A mixture of picloram, clopyralid and triclopyr has been used to test the activity and stability of the catalyst. These herbicides have been eliminated from aqueous media by several technologies such as Fenton, electro‐Fenton, photo‐Fenton, O 3 /H 2 O 2 , photocatalysis, UV and H 2 O 2 /UV, etc. However, to the best of the author's knowledge, the efficiency of photocatalytic ozonation has not been investigated for the removal of pyridine‐based herbicides.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic ozonation of pyridine‐based herbicides by N‐doped titania

Solís

Rivas

Gimeno

et al. 2015

J of Chemical Tech & Biotech

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BACKGROUND A mixture of three pyridine herbicides in water (clopyralid, triclopyr and picloram) has been treated with photocatalytic processes, involving oxygen or ozone. Nitrogen doped and undoped titania were used in the process. Toxicity evolution during photocatalytic ozonation was monitored considering BOD, Daphnia parvula and fitotoxicity trials. RESULTS N doped titania with an optimized photoactivity was tested in photocatalytic ozonation, leading to nearly 95% mineralization in 180 min. This catalyst was characterized by SEM, TEM, XRD and XPS techniques (13.5 nm crystal size, anatase phase, 1% N, and formation of O‐Ti‐N linkage). No loss of photocatalytic activity was observed after five consecutive runs. Although no toxicity from the parent compounds was observed, this parameter increased during the early stages of the oxidation process. When parent compounds were totally degraded and dechlorination was completed, toxicity decayed again to negligible values. CONCLUSION N doping improves bare titania photoactivity through an optimum amount of N. Photocatalysis/ozone showed better behavior than photocatalysis/oxygen in herbicide removal and mineralization, and no significant loss of activity was observed after five runs. Toxicity initially increased due to toxic byproducts formation; however, it decreased after their abatement. © 2015 Society of Chemical Industry

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Degradation of Clopyralid by the Fenton Reaction

Cited by 17 publications

References 30 publications

Photocatalytic ozonation of clopyralid, picloram and triclopyr. Kinetics, toxicity and influence of operational parameters

Photocatalytic ozonation of clopyralid, picloram and triclopyr. Kinetics, toxicity and influence of operational parameters

Stability of Cu species and zeolite structure on ecological heterogeneous Fenton discoloration–degradation of yellow 5 dye: Efficiency on reusable Cu‐Y catalysts

Photocatalytic ozonation of pyridine‐based herbicides by N‐doped titania

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