Inhibition vs. enhancement of the nitrate-induced phototransformation of organic substrates by the *OH scavengers bicarbonate and carbonate.
Contrary to common expectations, the hydroxyl scavengers, carbonate and bicarbonate, are able to enhance the phototransformation by nitrate of a number of substituted phenols. Carbonate and bicarbonate, in addition to modifying the solution pH, are also able to induce a considerable formation of the carbonate radicals upon nitrate photolysis. The higher availability of less-reactive species than the hydroxyl radical would contribute to substantially enhance the photodegradation of the phenols/phenolates that are sufficiently reactive toward the carbonate radical. This phenomenon has a potentially important impact on the fate of the relevant compounds in surface waters. In contrast, the degradation of compounds that are not sufficiently reactive toward CO(3)(-*) is inhibited by carbonate and bicarbonate because of the scavenging of *OH.
Vione
Davide
D
Dipartimento di Chimica Analitica, Università di Torino, Via Pietro Giuria 5, Turin, Italy. davide.vione@unito.it
Khanra
Swapan
S
Man
Simona Cucu
SC
Maddigapu
Pratap Reddy
PR
Das
Radharani
R
Arsene
Cecilia
C
Olariu
Romeo-Iulian
RI
Maurino
Valter
V
Minero
Claudio
C
D000465:Algorithms; D016227:Benzoquinones / Q000737:chemistry; D001639:Bicarbonates / Q000737:chemistry* / Q000494:pharmacology; D002254:Carbonates / Q000737:chemistry* / Q000494:pharmacology; D002396:Catechols / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D009566:Nitrates / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry; D055668:Photochemical Processes / Q000187:drug effects / Q000528:radiation effects; D010782:Photolysis / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
D016227:Benzoquinones; D001639:Bicarbonates; D002254:Carbonates; D002396:Catechols; D016166:Free Radical Scavengers; D009566:Nitrates; D010636:Phenols; C004532:quinone