Application of coumarin and coumarin-3-carboxylic acid for the determination of hydroxyl radicals during different advanced oxidation processes

Máté Náfrádi, Luca Farkas, Tünde Alapi, Klára Hernádi, Krisztina Kovács, László Wojnárovits, Erzsébet Takács

Research output: Article

Abstract

Transformation of coumarin (COU) and coumarin-3-carboxylic acid (3-CCA), the formation of their fluorescent hydroxylated products, (7-hydroxy-coumarin (7-HO-COU) and 7-hydroxy-3-carboxycoumarinic acid (7-HO-3-CCA)) were investigated and compared using three different advanced oxidation processes: gamma radiolysis, VUV (172 nm) photolysis and heterogeneous photocatalysis (TiO2/UV (300–400 nm)). Beside OH (hydroxyl radical), other reactive species: H (H-atom, in VUV irradiated aqueous solution and in gamma radiolysis with low yield) and eaq (hydrated electron, in gamma radiolysis) also contributed to the degradation. The reaction rate constants of COU and 3-CCA with each reactive species were determined via pulse radiolysis. The values obtained were: 6.88 × 109 and 4.9 × 109 with OH; 2.5 × 109 and 1.3 × 109 with H; 11.4 × 109 and 14.3 × 1010 mol−1 dm3 s−1 with eaq , in the case of COU and 3-CCA, respectively. Based on the results of radiolysis it was suggested, that the formation of fluorescent products are initiated only by OH. The effects of dissolved O2 and OH scavengers (MeOH and t-BuOH) were also investigated. In radiolysis dissolved O2 increased the formation rate of fluorescent products. In VUV photolysis of COU and 3-CCA solutions the inhibition effect of alcohols was more pronounced in the presence of O2 than in its absence. In heterogeneous photocatalysis both MeOH and t-BuOH decreased the transformation rate of COU, while they had no observable effect on that of 3-CCA, which is well adsorbed on TiO2 surface.

Original languageEnglish
Article number108610
JournalRadiation Physics and Chemistry
Volume170
DOIs
Publication statusPublished - máj. 2020

Fingerprint

hydroxyl radicals
radiolysis
carboxylic acids
oxidation
photolysis
products
reaction kinetics
alcohols
degradation
aqueous solutions
acids
pulses
atoms
electrons

ASJC Scopus subject areas

  • Radiation

Cite this

@article{5217f1876af44f35bfef5df3399f0ac3,
title = "Application of coumarin and coumarin-3-carboxylic acid for the determination of hydroxyl radicals during different advanced oxidation processes",
abstract = "Transformation of coumarin (COU) and coumarin-3-carboxylic acid (3-CCA), the formation of their fluorescent hydroxylated products, (7-hydroxy-coumarin (7-HO-COU) and 7-hydroxy-3-carboxycoumarinic acid (7-HO-3-CCA)) were investigated and compared using three different advanced oxidation processes: gamma radiolysis, VUV (172 nm) photolysis and heterogeneous photocatalysis (TiO2/UV (300–400 nm)). Beside •OH (hydroxyl radical), other reactive species: H• (H-atom, in VUV irradiated aqueous solution and in gamma radiolysis with low yield) and eaq − (hydrated electron, in gamma radiolysis) also contributed to the degradation. The reaction rate constants of COU and 3-CCA with each reactive species were determined via pulse radiolysis. The values obtained were: 6.88 × 109 and 4.9 × 109 with •OH; 2.5 × 109 and 1.3 × 109 with H•; 11.4 × 109 and 14.3 × 1010 mol−1 dm3 s−1 with eaq −, in the case of COU and 3-CCA, respectively. Based on the results of radiolysis it was suggested, that the formation of fluorescent products are initiated only by •OH. The effects of dissolved O2 and •OH scavengers (MeOH and t-BuOH) were also investigated. In radiolysis dissolved O2 increased the formation rate of fluorescent products. In VUV photolysis of COU and 3-CCA solutions the inhibition effect of alcohols was more pronounced in the presence of O2 than in its absence. In heterogeneous photocatalysis both MeOH and t-BuOH decreased the transformation rate of COU, while they had no observable effect on that of 3-CCA, which is well adsorbed on TiO2 surface.",
keywords = "172 nm VUV photolysis, Adsorption, Heterogeneous photocatalysis, Hydroxyl radical, Radiolysis",
author = "M{\'a}t{\'e} N{\'a}fr{\'a}di and Luca Farkas and T{\"u}nde Alapi and Kl{\'a}ra Hern{\'a}di and Krisztina Kov{\'a}cs and L{\'a}szl{\'o} Wojn{\'a}rovits and Erzs{\'e}bet Tak{\'a}cs",
year = "2020",
month = "5",
doi = "10.1016/j.radphyschem.2019.108610",
language = "English",
volume = "170",
journal = "Radiation Physics and Chemistry",
issn = "0969-806X",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Application of coumarin and coumarin-3-carboxylic acid for the determination of hydroxyl radicals during different advanced oxidation processes

AU - Náfrádi, Máté

AU - Farkas, Luca

AU - Alapi, Tünde

AU - Hernádi, Klára

AU - Kovács, Krisztina

AU - Wojnárovits, László

AU - Takács, Erzsébet

PY - 2020/5

Y1 - 2020/5

N2 - Transformation of coumarin (COU) and coumarin-3-carboxylic acid (3-CCA), the formation of their fluorescent hydroxylated products, (7-hydroxy-coumarin (7-HO-COU) and 7-hydroxy-3-carboxycoumarinic acid (7-HO-3-CCA)) were investigated and compared using three different advanced oxidation processes: gamma radiolysis, VUV (172 nm) photolysis and heterogeneous photocatalysis (TiO2/UV (300–400 nm)). Beside •OH (hydroxyl radical), other reactive species: H• (H-atom, in VUV irradiated aqueous solution and in gamma radiolysis with low yield) and eaq − (hydrated electron, in gamma radiolysis) also contributed to the degradation. The reaction rate constants of COU and 3-CCA with each reactive species were determined via pulse radiolysis. The values obtained were: 6.88 × 109 and 4.9 × 109 with •OH; 2.5 × 109 and 1.3 × 109 with H•; 11.4 × 109 and 14.3 × 1010 mol−1 dm3 s−1 with eaq −, in the case of COU and 3-CCA, respectively. Based on the results of radiolysis it was suggested, that the formation of fluorescent products are initiated only by •OH. The effects of dissolved O2 and •OH scavengers (MeOH and t-BuOH) were also investigated. In radiolysis dissolved O2 increased the formation rate of fluorescent products. In VUV photolysis of COU and 3-CCA solutions the inhibition effect of alcohols was more pronounced in the presence of O2 than in its absence. In heterogeneous photocatalysis both MeOH and t-BuOH decreased the transformation rate of COU, while they had no observable effect on that of 3-CCA, which is well adsorbed on TiO2 surface.

AB - Transformation of coumarin (COU) and coumarin-3-carboxylic acid (3-CCA), the formation of their fluorescent hydroxylated products, (7-hydroxy-coumarin (7-HO-COU) and 7-hydroxy-3-carboxycoumarinic acid (7-HO-3-CCA)) were investigated and compared using three different advanced oxidation processes: gamma radiolysis, VUV (172 nm) photolysis and heterogeneous photocatalysis (TiO2/UV (300–400 nm)). Beside •OH (hydroxyl radical), other reactive species: H• (H-atom, in VUV irradiated aqueous solution and in gamma radiolysis with low yield) and eaq − (hydrated electron, in gamma radiolysis) also contributed to the degradation. The reaction rate constants of COU and 3-CCA with each reactive species were determined via pulse radiolysis. The values obtained were: 6.88 × 109 and 4.9 × 109 with •OH; 2.5 × 109 and 1.3 × 109 with H•; 11.4 × 109 and 14.3 × 1010 mol−1 dm3 s−1 with eaq −, in the case of COU and 3-CCA, respectively. Based on the results of radiolysis it was suggested, that the formation of fluorescent products are initiated only by •OH. The effects of dissolved O2 and •OH scavengers (MeOH and t-BuOH) were also investigated. In radiolysis dissolved O2 increased the formation rate of fluorescent products. In VUV photolysis of COU and 3-CCA solutions the inhibition effect of alcohols was more pronounced in the presence of O2 than in its absence. In heterogeneous photocatalysis both MeOH and t-BuOH decreased the transformation rate of COU, while they had no observable effect on that of 3-CCA, which is well adsorbed on TiO2 surface.

KW - 172 nm VUV photolysis

KW - Adsorption

KW - Heterogeneous photocatalysis

KW - Hydroxyl radical

KW - Radiolysis

UR - http://www.scopus.com/inward/record.url?scp=85076167318&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85076167318&partnerID=8YFLogxK

U2 - 10.1016/j.radphyschem.2019.108610

DO - 10.1016/j.radphyschem.2019.108610

M3 - Article

AN - SCOPUS:85076167318

VL - 170

JO - Radiation Physics and Chemistry

JF - Radiation Physics and Chemistry

SN - 0969-806X

M1 - 108610

ER -