ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 6, pp. 1084!1086. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + G.A. Mandrov, E.L. Schastlivtsev, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 6, pp. 1045!1046.
Sedimentation of Carbon-Clay Dispersions
with Polyacrylamide Modified with Tetraethylene Glycol
G. A. Mandrov and E. L. Schastlivtsev
Institute of Coal and Coal Fuel Chemistry, Siberian Division,
Russian Academy of Sciences, Kemerovo, Russia
Received April 24, 2007
Abstract-Sedimentation of carbon-clay dispersions with polyacrylamide modified with tetraethylene
glycol was studied. The concept of the formation of a binary structure of the modified polymer in
a structured ternary system was formulated.
Improvement of the flocculation activity of do-
mestic flocculants is still a topical problem for clar-
ification of recycled water at coal-cleaning plants.
As shown previously , modification of polyacryl-
amide (PAA)with a-propylene chlorohydrin (poly-
mer concentration 0.4 mg dm
)raises the rate of
sedimentation of carbon-clay dispersions (mean
particle size 2.25 mm)by approximately a factor
In this study, we examined the possibility of en-
hancing the flocculation activity of domestic PAA.
Taking into account that the flocculation activity
of a PAA increases with its molecular weight, it
was of particular interest to study the floccula-
tion activity of PAA as influenced by the monomer
chain length in the course of its modification with
tetraethylene glycol (TEG). For dilute solutions,
it was important to estimate changes in the specific
viscosity on passing from the straight polymer so-
lution to the binary system:
where h and h
are the viscosities of the polymer
solution and solvent, respectively.
First, the viscosities of the polymer solutions
were determined from their outflow time using
a capillary viscometer, and then their intrinsic vis-
cosities [h] were graphically determined and used
to calculate the viscosity-average molecular weight
of the polymer from the Mark3Kuhn3Houwink
where K and a are constants for a given polymer3
For the PAA3water system, K = 0.63 0 10
and a = 0.8 . Using known K and a,[h] was
determined from the intercept on the ordinate axis
As the parameters characterizing the size and
shape of macromolecules, we estimated the mean
distance between the ends of the polymer molecular
chain h and the polymer flexibility G, i.e., the h/M
ratio. The quantity h characterizes the reactivity of
macromolecules in the course of flocculation.
The mean statistical distance between the ends of
Fig. 1. Relative viscosity of flocculant solutions h vs.
their concentration ?.() PAA and ( ) PAA + TEG;
the same for Fig. 2. (h) Relative viscosity, h = h