ISSN 1070-4272, Russian Journal of Applied Chemistry, 2017, Vol. 90, No. 1, pp. 47−52. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © E.N. Krutsko, O.N. Musskaya, A.I. Kulak, V.K. Krut’ko,
2017, published in Zhurnal Prikladnoi Khimii, 2017, Vol. 90, No. 1, pp. 51−57.
Of particular interest in the last decade have been
cements containing photocatalysts (mostly titanium
) [1–7] with surface self-cleaning under
the solar irradiation. In the photocatalytic process
with titanium dioxide, activity is exhibited by the UV
component of solar light, with photon energy exceeding
3.2 eV (at λ < 388 nm), the absorption of which
activates photodestruction processes [8–10] and imparts
superhydrophilic properties to the surface .
The known photocatalytically active cements are
based on the conventional binding construction mixes
formed, as a rule, from Portland cement with addition of
titanium dioxide of anatase modiﬁ cation [1, 6, 7]. It is
known that, owing to the simplicity, economic efﬁ ciency,
low energy consumption in their manufacture, easy
molding, good steam and air permeability, and other
properties, gypsum cements ﬁ nd wide use in construction
activities as a material for internal works .
To make wider the assortment of binders used in
photocatalytic cements, we examined in the present study
the photocatalytic properties of gypsum binders with
addition of a titanium dioxide photocatalyst. Because of
the differences in the chemical composition of building
gypsum plasters and depending on the raw materials, we
used in the present study pure synthetic calcium sulfate
along with the gypsum construction-grade cement.
Gypsum cements were produced by mixing a powder
of industrial gypsum building plaster [STB (Standard
of the Republic of Belarus) 1263–2001] or synthetic
calcium sulfate hemihydrate CaSO
O with distilled
water at a mass ratio of 1 : (0.4–0.9). Calcium sulfate
hemihydrate was formed by partial dehydration at 160°C
during 1 h of calcium sulfate dihydrate CaSO
synthesized by the procedure described in  from the
starting reagents CaNO
O (analytically pure grade)
(chemically pure). As a photocatalyst served
Hombikat UV100, which was added
into the cement mixture in amounts of 2, 5, and 10 wt
%. The resulting cement mixture was used to obtain 4 ×
11 × 22 m bricks dried in air for 24 h.
An X-ray analysis (XRD) of the samples was made
with a Bruker Advance D8 diffractometer (Germany)
radiation (λ = 1.54056 Å).
The acidity of the cements was determined as
follows: monolithic samples ground to particle size of
200–1000 μm were kept in distilled water (20 mL of water
per 1 g of cement) for two days with periodic agitation
of the suspension, and the pH value was measured with
a HANNA HI 221 desktop pH-meter (Romania).
Photocatalytic Activation of Gypsum Cements
E. N. Krutsko*, O. N. Musskaya, A. I. Kulak, and V. K. Krut’ko
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received January 24, 2017
Abstract—Photocatalytic activity of gypsum cements that are based on the building plaster blend and synthetic
calcium sulfate and contain 2–10 wt % titanium dioxide of anatase modiﬁ cation was studied. The decomposition
rate of the model contaminant (Rhodamine C) on the surface of a plaster blend containing 2 wt %TiO
seven times higher under exposure to a full spectrum of a UV lamp, and 29 times higher under UV-A irradiation
at λ > 320 nm. It was found that there are two competing processes (photocatalysis and direct photolysis), which
affect the decomposition rate of Rhodamine C on the surface of the cements, depending on the UV irradiation