Dr. Ivan Pozdnyakov
Novosibirsk State University, Russia
Title: Correct determination of quantum yields of hydroxyl radical generation upon photolysis of natural Fe(III) carboxylates
Abstract:
Fe (III)
carboxylate complexes are photoactive natural compounds that are intensively
studied and are considered to be one of the promising systems for the
degradation of pollutants in the so-called advanced oxidation processes (AOPs).
They demonstrate high quantum yields of photolysis and efficient generation of •OH
radicals under the action of UV radiation. However, there is very little
information on the quantum yields of •OH radicals (_/OH) upon excitation of such systems and relation
of _/OH values with quantum yield of photolysis of
Fe(III) carboxylates (_/phot). At the same time, the _/OH values and the reactivity of •OH
with respect to the target compounds are the most important parameters for the
application of any photosystem in AOPs. This work presents valid approach to
determining both _/OH and _/phot values during UV photolysis of natural Fe(III)
carboxylate complexes and to establishing correlation between these parameters.
The
approach [1,2] is based on the use of the FeOH2+ hydroxocomplex as a
reference system with the well-known _/OH value and benzene as a selective trap for •OH
radicals. For the first time [1], _/OH was determined for the most popular Fe(III)-oxalate
photosystem in a wide range of initial parameters (pH, excitation wavelength,
concentration of oxalate and Fe(III) ions). Also, the oxidative potential of
the oxalate photosystem was tested on a set of resistant organic herbicides,
and the quantum yields of photodegradation of these herbicides were compared
with the _/OH value [1]. It was shown that dark processes of
Fe(II) reoxidation by dissolved oxygen play an important role in correct
determination of both _/OH and _/phot values and correct procedure of calculation of
this parameters from experimental data was proposed [2]. Good linear
correlation between _/OH and _/phot was established for a set of natural Fe(III)
carboxylates.
This work was financially supported by the Russian Science Foundation
(No. 21-43-00004).
[1] Yu.E. Tyutereva, M.V. Novikov, O.A. Snytnikova and I.P. Pozdnyakov,
How to measure quantum yield of hydroxyl radical during photolysis of natural
Fe(III) carboxylates? Chemosphere, 298 (2022) 134237 DOI:
10.1016/j.chemosphere.2022.134237
[2] Yury A. Belikov, Olga A. Snytnikova, Vyacheslav P. Grivin, Victor F.
Plyusnin, Jing Xu, Feng Wu and Ivan P. Pozdnyakov, Photolysis of Fe(III)
complex with ethylenediamine-N,N'-disuccinic acid and its efficiency in
generation of •OH radical, Chemosphere, 309 (2022) 136657, DOI:
10.1016/j.chemosphere.2022.136657
Biography: