The Carbonate Radical (HCO3·/CO3-·) as a Reactive Intermediate in Water Chemistry: Kinetics and Modelling

Umschlag, Th.; Herrmann, Hartmut

doi:10.1002/(sici)1521-401x(199907)27:4<214::aid-aheh214>3.0.co;2-6

Cited by 59 publications

(24 citation statements)

References 22 publications

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“…The reactivity of carbonate radical produced by the quenching reactions (5) and (6), might not be negligible according to the nature of the molecule (Umschlag and Herrmann 1999, Huang and Mabury 2000a, 2000b, 2000c. It was, therefore, of great importance to quantify its reactivity towards carbendazim.…”

Section: Degradation Of Carbendazim By Hydroxyl and Carbonate Radicalssupporting

confidence: 79%

Degradation of carbendazim by UV/H 2 O 2 investigated by kinetic modelling

Mazellier

Leroy

Laat

et al. 2003

Environmental Chemistry Letters

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The transformation of the fungicide carbendazim (methyl-2 benzimidazole carbamate) induced by hydroxyl radical generated by the UV photolysis of H 2 O 2 has been studied in dilute aqueous solution. The efficient reaction of hydroxyl radicals with carbendazim led to the rapid degradation of carbendazim. The study of reaction kinetics yielded a second order rate constant of 2.2±0.3 10 9 M −1 s −1 for HO · radicals with carbendazim. This value is in agreement with a high reactivity of HO · radicals with carbendazim. Most degradation products were identified by high performance liquid chromatography mass spectrometry (HPLC-MS). In the presence of hydrogenocarbonate and carbonate ions, hydroxyl radicals were quenched and in turn carbonate radicals CO 3 ·− were formed. Carbonate radicals are indeed known to react efficiently with compounds containing electron-rich sites such as nitrogen or sulfur atoms. The use of a kinetic modelling software gave evidence for the occurrence of such reactions with carbendazim. The second order rate constant of carbonate radical with carbendazim was equal to 6±2 10 6 M −1 s −1 .

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Section: Degradation Of Carbendazim By Hydroxyl and Carbonate Radicalssupporting

confidence: 79%

Degradation of carbendazim by UV/H 2 O 2 investigated by kinetic modelling

Mazellier

Leroy

Laat

et al. 2003

Environmental Chemistry Letters

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“…The carbonate radical (CO ÅÀ 3 ) generated by the reaction (6) is reported to yield a reduction potential E°( CO ÅÀ 3 ; H þ =HCO À 3 ) of 1.63 V at pH 8.4 and 1.59 V at pH 12 (Zuo et al, 1999). They was shown to be strong enough to degrade PAHs (Umschlag and Herrmann, 1999). It has also been suggested that chloride radicals can participate in propagation reactions with oxidants and thereby not be entirely unproductive (Yu et al, 2004).…”

Section: Peroxodisulfate (S 2 O 2àmentioning

confidence: 99%

Influence of chloride and carbonates on the reactivity of activated persulfate

2012

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Chloride and carbonates have the potential to impact pathway, kinetics, and efficiency of oxidation reactions, both as radical scavengers and as metal complexing agents. Traditionally, it is assumed that they have an overall negative impact on the activated persulfate performance. This study investigated the influence of carbonates and chloride on the reactivity of persulfate for three different activation techniques to produce reactive free sulfate radicals; heat, alkaline and iron activation. By using p-nitrosodimethylaniline as model target compound, it was demonstrated that iron activation at neutral pH was not affected by Cl(-) or HCO(3)(-), alkaline activation was enhanced by Cl(-) and even more by CO(3)(2-), and heat activation was enhanced by Cl(-), and no effect from HCO(3)(-) was observed. At pH 2 destruction of perchloroethylene by iron activated persulfate was significantly affected by chloride. Reaction rates decreased, but the overall oxidation efficiency was unaffected up to 28 mM Cl(-). The effect of chloride and carbonates is caused by direct attack of produced reactive chlorine, or carbonate species or by catalysis of the propagation reactions resulting in more sulfate radicals. These results show that carbonate and chloride might play an important role in activated persulfate applications and should not strictly be considered as scavengers.

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“…A compilation of rate constants is available for reaction of carbonate radical with 181 organic and inorganic compounds [18], but the number of available rate constants with organic compounds is steadily increasing [73,75–79]. A series of mono‐substituted benzene derivatives [80] yielded the following QSAR: …”

Section: Qsars Of Oxidants In Aqueous Solutionmentioning

confidence: 99%

Quantitative structure‐activity relationships for oxidation reactions of organic chemicals in water

Canonica

Tratnyek

2003

Enviro Toxic and Chemistry

106

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Abstract-Even in the absence of microbiological mediation, oxidation is one of the most important chemical processes contributing to the degradation of organic contaminants in the aquatic environment. The oxidants that are responsible for these reactions include hydroxyl radical, carbonate radical, organic oxyl and peroxyl radicals, peroxides, excited triplet states of organic chromophores, singlet molecular oxygen, ozone, chlorine dioxide, permanganate, and chromate. Some of these oxidants contribute to natural attenuation of organic contaminants, but many are of greater interest because of their role in engineered remediation technologies. Kinetic studies of these processes have lead to numerous quantitative structure-activity relationships (QSARs). Many of these QSARs are simple empirical correlations to common convenient descriptor variables like Hammett constants (), half-wave oxidation potentials (E ½ ), energies of the highest occupied molecular orbital (E HOMO ) or rate constants for other oxidation reactions. However, several environmentally relevant, aqueous-phase oxidation reactions have been described with QSARs based on theoretical models for electron transfer that were developed by Marcus-Hush and Rehm-Weller. This review summarizes many of the reported QSARs for aquatic oxidations of organic compounds with emphasis on the interrelation between traditional empirical models and the potential for future development of QSARs based on theoretical models.

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The Carbonate Radical (HCO3·/CO3-·) as a Reactive Intermediate in Water Chemistry: Kinetics and Modelling

Cited by 59 publications

References 22 publications

Degradation of carbendazim by UV/H 2 O 2 investigated by kinetic modelling

Degradation of carbendazim by UV/H 2 O 2 investigated by kinetic modelling

Influence of chloride and carbonates on the reactivity of activated persulfate

Quantitative structure‐activity relationships for oxidation reactions of organic chemicals in water

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