Wydział Chemii

Irmina Ćwieląg-Piasecka

Maciej Witwicki

Maria Jerzykiewicz

Julia Jezierska

2017

Environmental Science and Technology

51

14124-14134

10.1021/acs.est.7b03386

Naukowa

Angielski

Artykuł

Radical oxidation of carbamate insecticides, namely carbaryl and carbofuran, was investigated with spectroscopic (electron paramagnetic resonance [EPR] and UV–vis) and theoretical (density functional theory [DFT] and ab initio orbital-optimized spin-component scaled MP2 [OO-SCS-MP2]) methods. The two carbamates were subjected to reaction with ^•OH, persistent DPPH^• and galvinoxyl radical, as well as indigenous radicals of humic acids. The influence of fulvic acids on carbamate oxidation was also tested. The results obtained with EPR and UV–vis spectroscopy indicate that carbamates can undergo direct reactions with various radical species, oxidizing themselves into radicals in the process. Hence, they are prone to participate in the prolongation step of the radical chain reactions occurring in the soil environment. Theoretical calculations revealed that from the thermodynamic point of view hydrogen atom transfer is the preferred mechanism in the reactions of the two carbamates with the radicals. The activity of carbofuran was determined experimentally (using pseudo-first-order kinetics) and theoretically to be noticeably higher in comparison with carbaryl and comparable with gallic acid. The findings of this study suggest that the radicals present in soil can play an important role in natural remediation mechanisms of carbamates.

http://dx.doi.org/10.1021/acs.est.7b03386

https://www.acs.org/content/acs/en.html