Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 10, pp. 1894−1897.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
I.V. Shestak, E.V. Vorob’eva, I.I. Basalyga, N.P. Krut’ko, A.D. Vorob’ev, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82,
No. 10, pp. 1742−1745.
AND POLYMERIC MATERIALS
Polyacrylic Acid and Formulations Based on It as Inhibitors
of Deposit Formation in Water-Recycling Systems
I. V. Shestak, E. V. Vorob’eva, I. I. Basalyga, N. P. Krut’ko, and A. D. Vorob’ev
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received November 27, 2008
Abstract—The performance of polyacrylic acid of various molecular weights and of its formulations with sodium
tripolyphosphate and Na2EDTA as inhibitors of deposit formation and as dispersants was examined..
To mitigate the detrimental effect of industry on
the environment, industrial enterprises should utilize
natural waters with maximal efﬁ ciency. One of the main
ways to meet this requirement is reuse of water in the
production, which makes it necessary to provide water
recycling with cooling of technical water that has been
heated in the industrial process. As a rule, water is cooled
by evaporation in cooling towers. Evaporation leads to
concentration of soluble and insoluble impurities present
in water, and conditions arise for deposition of hardness
salts in heat exchangers, which decreases the efﬁ ciency
of heat transfer, causes increased power consumption,
and makes it necessary to interrupt the production process
to perform expensive and time-consuming operations
of equipment cleaning. Furthermore, deposit formation
stimulates subsurface corrosion leading to premature
wear of the equipment.
One of efﬁ cient solutions of the problem of deposit
formation in water-recycling systems is the use of special
chemical reagents inhibiting scale formation. Among
such reagents, the most widely used are phosphates,
phosphorus-containing complexones (phosphonates),
and polyelectrolytes [1, 2]. Inhibitors affect the
formation, growth, and structure of scale crystals [2,
3]. Polyelectrolytes, in particular, those based on
polyacrylic, polymethacrylic, and polymaleic acids and on
polyacrylamide ﬁ nd growing use today. The mechanism
of the inhibiting effect of reagents of this group differs
from that of phosphorus-containing compounds and is
yet poorly understood.
It should be noted that, to reliably eliminate scale
formation, the reagent should exhibit good dispersing
properties toward a series of substances: microcrystals of
hardness salts and their agglomerates, corrosion products,
clay particles, so as to stabilize the precipitate of insoluble
impurities in the suspended form for a long time .
In this study we examined the performance of
polyacrylic acid (PA) and its formulations with sodium
tripolyphosphate and Na
EDTA as scale formation
inhibitors and dispersants.
As inhibitors of deposit formation we used polyacrylic
acid samples with MW 1000, 2100, 3000, 5000, and
78 000 (PA
) purchased from
Aldrich, sodium tripolyphosphate [STPP, GOST
(State Standard) 13493–86], and disodium dihydrogen
EDTA (GOST 10652–
73). Solutions of calcium and magnesium chlorides and
of sodium hydrogen carbonate were prepared in distilled
water from chemically pure grade chemicals.
To evaluate the performance of the inhibitors, we
used a PMAC SCL-30P-2A laboratory installation (the
United Kingdom) simulating the deposit formation under
real conditions. The principle of its operation consists
in dynamic measurement of the differential pressure
in a metallic capillary, increasing as a result of scale
formation, at variable or ﬁ xed experimental parameters.