ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 464 ! 469. + Pleiades Publishing, Inc., 2006.
Original Russian Text + I.A. Novakov, S.S. Radchenko, A.S. Pastukhov, F.S. Radchenko, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79,
No. 3, pp. 472! 477.
AND POLYMERIC MATERIALS
Water-Soluble Polymer!Colloid Complexes of Aluminum
Polyhydroxochloride and Polyethylenimine in Separation
of Dispersions at Low pH
I. A. Novakov, S. S. Radchenko, A. S. Pastukhov, and F. S. Radchenko
Volgograd State Technical University, Volgograd, Russia
Received November 8, 2005
Abstract-Interaction of polyethylenimine with aluminum salts in aqueous solutions was studied; in the
process, polymer!colloid complexes exhibiting elevated activity in separation of dispersions with low pH are
Polymer3colloid complexes (PCCs) are new specif-
ic macromolecular compounds formed by interaction
of water-soluble organic polymers with the surface
of colloidal particles . Though PCCs may have
different structures, depending on both the nature of
colloidal particles and type of functional groups in the
polymer macromolecules, they are all water-soluble.
These complexes are of particular importance for floc-
culation of colloidal dispersions and can be used in
treatment of wastewater and in design of closed
environmentally safe treatment cycles [4, 5].
Aluminum aquahydroxo complexes are formed as
colloidal particles in concentrated aqueous solutions of
aluminum pentahydroxochloride (APHC) . It was
found [7, 8] that the reaction of APHC with polyacryl-
amide (PAA) in aqueous solution yields PCCs ex-
hibiting high flocculation activity in separation of
model and real aqueous dispersions. Along with PAA,
numerous water-soluble polymers with ionizable func-
tional groups [including polyethylenimine (PEI)] can
be used to prepare PCCs.
In this study we examined the flocculation proper-
ties of the compounds formed in aqueous solutions by
APHC colloidal particles with PEI in separation of
model and real dispersions.
In this study we used APHC prepared by the known
procedure  (Al
content 12.8 wt %, Cl
atomic ratio 0.48, pH 4.5, r 1330 kg m
, dry residue
46.8 wt %) and PEI (molecular weight 30 000340 000)
purchased from Serva (the United States).
The composition of PCC of the polymer with
APHC was studied with an Ubbelohde viscometer
0.25 mm) at 30+ 0.1oC. For this purpose,
the solution pH was adjusted to 4.5 with 0.1 N HCl;
the pH measurements were carried out with a pH-300
pH-meter (Hanna Instruments, the United States)
equipped with an HI 1131 combined electrode. Before
the viscosity measurements, the solutions were aged
for 2 days.
The polymeric complexes were prepared by mixing
the aqueous solutions of PEI (1 wt %) and APHC at
room temperature; the Al
: PEI unit ratio was varied
from 0.25 to 10.0. To prepare PCC, the resulting solu-
tion was stored for 2 days at room temperature.
A model kaolin dispersion (0.8 wt %) was prepared
using kaolin [technical grade, GOST (State Standard)
19.608384] and tap water (pH 7.8) and swollen for
3 h. Before the experiments, the dispersion was thor-
oughly mixed and poured in 250-ml glass cylinders.
Then the required amounts (charges) of the flocculant
solution with a concentration from 2 to 20 mg l
were added, and the resulting suspensions were stirred
with disc stirrers for 30 min. After storage for 20 min,
the optical density D of the supernatant was measured
on a KFK-3 device (l = 460 nm, l =135 cm). Using
the spectrophotometric procedure [9, 10], the clarifica-
tion effect E
was calculated as a dimensionless
parameter characterizing the flocculation process:
are the supernatant turbidities in