abstract
The photochemical degradation of 2-mercaptobenzothiazole (MBT) and 1,2,3-benzotriazole (BTA) inhibitors was studied in the present work in aqueous and in organic solutions. The extent of photo-degradation was assessed by UV-Vis spectroscopy and the main reaction products were identified by tandem electrospray ionization mass spectrometry (ESI-MS/MS). The analysis of degradation products upon UV irradiation revealed the predominant formation of dimeric compounds from MBT and oligomeric structures from BTA, which were further converted into aniline. The increase of the quantum yield of MBT and BTA photodegradation reactions under aerobic conditions both in aqueous and organic solvents was explained by an increase of the spin-orbit conversion of the singlet radical pairs into the triplet radical pairs in the presence of oxygen. These triplet pairs further dissociate into free radicals, or convert to the parent compounds. At the early stage of UV irradiation, free radical coupling leads essentially to dimer formation in the case of MBT and to the formation of oligomers in the case of BTA irradiation.
keywords
COPPER CORROSION; BENZOTRIAZOLE DERIVATIVES; HETEROCYCLIC-COMPOUNDS; PROTECTIVE-COATINGS; HYDROCHLORIC-ACID; ALUMINUM; STEEL; PHOTOCHEMISTRY; DEGRADATION; ADSORPTION
subject category
Chemistry; Physics
authors
Serdechnova, M; Ivanov, VL; Domingues, MRM; Evtuguin, DV; Ferreira, MGS; Zheludkevich, ML
our authors
Dmitry Evtyugin
Associate Professor with Aggregation
Maria Serdechnova
Post-doc Fellowship
Mário Guerreiro Silva Ferreira
Retired Professor
Mikhail Zheludkevich
Invited Principal ResearcherGroups
G3 - Electrochemical Materials, Interfaces and Coatings
G4 - Renewable Materials and Circular Economy
acknowledgements
The authors would like to thank Fundacao para a Ciencia e a Tecnologia em Portugal (FCT grants PEst-C/QUI/UI0062/2013, PEst-C/CTM/LA0011/2013 and FCOMP-01-0124-FEDER-037296); European FP7 projects