1070-4272/03/7609-1472$25.00C2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 9, 2003, pp. 1472!1475. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 9,
2003, pp. 1511!1514.
Original Russian Text Copyright + 2003 by Slavinskaya, Selemenev.
OF CHEMISTRY AND TECHNOLOGY
Ozonation of Fulvic Acids of Natural Waters
in Aqueous Solutions
G. V. Slavinskaya and V. F. Selemenev
Voronezh State University, Voronezh, Russia
Received March 26, 2003
Abstract-Ozonation of fulvic acids of natural waters in aqueous solutions was studied.
It is known that water chlorination gives rise to its
contamination with carcinogenic organic impurities
. Therefore, ozone is widely used today as oxidant
instead of chlorine in water treatment. Ozonation is
used for treating drinking and ultrapure water, for
breakdown of organic impurities in wastewater, etc.
. Ozonation of natural waters is actively studied
to elucidate the possibility of water decontamination
from ozonation products by various techniques, in-
cluding coagulation and sorption.
Taking into account that fulvic acids (FAs) are, as
a rule, the main organic impurity present in natural
waters, we studied in this work their ozonation in
Fulvic acids were isolated from Neva water by
the technique reported in . The ozonation of fulvic
acid solutions was carried out in a glass column of
bubble type 70 mm in diameter at pH 7.1 typical of
Neva water. The experiments on water treatment by
coagulation with iron sulfate combined with liming
were carried on the same column at pH 9. The air3
ozone flow containing 6.8310.0 mg dm
generated by an ozonizer with the performance of
at the air flow rate of about 1 dm
The difference between the ozone concentration in
the aqueous solution before and after its reaction with
FAs was determined by the method reported in .
As seen from Fig. 1, on ozonation of neutral FA
solutions, the color index measured at 350 nm (an
SF-46 spectrophotometer) decreases to a lesser extent
than on ozonation of weakly alkaline FA solutions.
The color of fulvic acids is due to the fact that
these molecules contain a polycyclic aromatic core
and peripheral chains, with a common system of con-
jugated double bonds giving a continuous absorption
band in the range 2003350 nm . On oxidation
with ozone, this chromophoric molecular system is
The FA degradation is manifested in the electronic
absorption spectra (Fig. 2) as a decrease in the optical
Fig. 1. Residual color index CI as a function of the ozone
amount Q that reacted with FAs at pH (1) 7 and (2) 9.0.
Fig. 2. Electronic absorption spectra of FAs (1) before and
(2) after ozonation. Q (mg mg
FA): (1)0,(2) 0.13,
(3) 0.23, and (4) 0.29. (A) Optical density and (l) is wave-