ISSN 0018-1439, High Energy Chemistry, 2018, Vol. 52, No. 3, pp. 212–216. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © I.M. Piskarev, 2018, published in Khimiya Vysokikh Energii, 2018, Vol. 52, No. 3, pp. 194–198.
Hydrogen Peroxide Formation in Aqueous Solutions
under UV-C Radiation
I. M. Piskarev
Skobeltsyn Research Institute of Nuclear Physics, Moscow State University, Moscow, 119234 Russia
Received July 31, 2017
Abstract⎯The formation of hydrogen peroxide in bidistilled water under the influence of UV-C radiation
from a DKB-9 low-pressure mercury lamp has been studied. The yield of hydrogen peroxide was (1 ± 0.2) ×
mol (L s)
. The wavelengths of radiation under the influence of which the formation of H
have been estimated. It has been assumed that the intermediate product of the reaction is the rad-
ical. To identify it, oxidation–reduction reactions in aqueous solutions containing Fe
, and I
pH values from 0.8 to 8.1 have been studied. The quantum yield of radicals in an acidic medium under
the influence of radiation from the mercury lamp is 0.015 ± 0.005.
Keywords: hydrogen peroxide, radical, Fe
oxidation, UV-C radiation
Mechanisms of the interaction of UV-C radiation
that can pass through air (200–280 nm) with the mat-
ter have been studied for a long time are well docu-
mented. There are monographs summarizing these
studies [1, 2]. One of the mechanisms is the direct
absorption of a photon by an energy level of a molecule
(provided that such a level exists) followed by the tran-
sition of the molecule to an excited state in which it
can undergo further transformations. If there is no
such energy level in the molecule, and dissolved oxy-
gen is present in the water, then reactions of type I and
II with a sensitizer in the triplet state are possible. Any
impurity in water can act as a sensitizer. The radi-
cal ion is formed in type I reaction, the reaction of
type II generates singlet oxygen .
In natural waters, there are always substances that
can play the role of a sensitizer; therefore, hydrogen
peroxide is formed in natural water under the influ-
ence of visible and UV radiation [4, 5]. In the case of
UV-C radiation with λ < 246 nm, the decomposition
of water molecules with the formation of hydroxyl rad-
icals is feasible in the absence of sensitizers in water.
However, the probability of this process is low .
Hydroxyl radicals are formed with a noticeable proba-
bility under the influence of vacuum ultraviolet at λ <
Gudkov et al.  studied the formation of hydro-
gen peroxide in bidistilled water under the inf luence of
sunlight and artificial illumination with an electric
bulb. The treatment of a 20-mL sample of water with
solar radiation for 1 to 5 h resulted in the formation of
30 to 200 nmol (concentration from 1.5 × 10
mol/L) of hydrogen peroxide. Illumination
with an electric bulb for the same time gave
8 to 16 nmol (concentration from 4 × 10
up to 8 ×
mol/L) of hydrogen peroxide. The participation
of radicals in this process was shown.
In [8, 9], it was shown that radicals can
be formed in water by the action of UV-C radiation.
The radicals are in the following equilibrium:
↔ + H
= 4.8. (1)
Depending on the acidity of the medium, the radi-
cal exists in different forms. In , the yield of on
a beam of pulse and continuous UV-C radiation in an
acidic medium was estimated. The interaction of
radicals with one another should lead to the formation
of hydrogen peroxide. However, hydrogen peroxide
was not detected in [8, 9].
The formation of radicals can be consid-
ered as a new mechanism of the interaction of photons
of visible and ultraviolet ranges with aqueous solu-
tions. Therefore, it is of interest to obtain information
on the formation of radicals under the influ-
ence of UV-C radiation in pure water and in aqueous
solutions of substances that cannot exist in the triplet