Preparation and coagulation performance of hybrid coagulant
polyacrylamide–polymeric aluminum ferric chloride
Xinlei Wang , Shaojie Jiang , Siying Tan, Xun Wang, Hongwu Wang
Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment (State Ministry of Education),
Chongqing University, Chongqing 40045, China
Correspondence to: S. Jiang (E-mail: email@example.com)
In this study, we synthesized a novel hybrid coagulant, polyacrylamide (PAM)–polymeric aluminum ferric chloride
(PAFC), by the polymerization of acrylamide monomer with the redox system (NH
. The factors affecting the PAM–
PAFC hybrid coagulant were investigated in an orthogonal experiment. The maximum intrinsic viscosity was observed at an initiator
mass fraction of 0.5%, a polymerization temperature of 50 8C, a monomer mass fraction of 20%, and a polymerization time of 4 h,
which were the optimum synthesis parameters. The spatial network structure of the PAM–PAFC hybrid coagulant was graphically
determined by scanning electron microscopy. Hybrid PAM–PAFC was adopted to treat the kaolin–humic acid suspension and the
synthetic dye wastewater. The effect of the coagulant dosage and pH on the coagulant experiments were examined. The coagulant
experiment on the kaolin–humic acid suspension showed that the optimum treatment efficiency was achieved at a coagulants dosage
of 0.6 mg/L, at which level the turbidity reductions with the inorganic PAFC coagulant, PAM–PAFC composite, and PAM–PAFC
hybrid were 95.30%, 95.84%, and 98.38%, respectively. Treatment with the PAM–PAFC hybrid coagulant was also effective in remov-
ing Congo Red and Direct Fast Turquoise Blue GL; the color-removal efficiencies for these dyes were higher than 93% and 94%,
2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46355.
applications; copolymers; dyes/pigments; inorganic polymers
Received 15 September 2017; accepted 9 February 2018
The production of composite materials is a developing tendency
in modern materials.
Excellent properties can be obtained in
materials by compounding multiple materials with different
functions to achieve complementary and optimal performances.
An organic–inorganic hybrid material is essentially different
from traditional composite materials, and it has many superior
properties, such as a larger interfacial area and strong interfacial
interactions between the polymer chains and inorganic particles.
A hybrid material’s interface is blurred, and its microsize is on
the nanometer scale or even down to the level of a molecular
compound in some cases.
Nowadays, research on hybrid mate-
rials is almost in the field of materials,
but there have been
limited reports on the use of hybrid materials in coagulants.
Coagulation is a common process in water and wastewater treat-
ment. Fe(III) salts and Al(III) salts are the most commonly used
coagulants in water treatment.
However, aluminum is suspected to
be harmful to humans and other living organisms,
and ferric coag-
ulants need a large amount of alkali to resist the pH depression that
occurs during coagulation.
In recent years, the number of reports
on polymeric aluminum ferric chloride (PAFC) as an efficient inor-
ganic polymer coagulant have increased.
PAFC, which com-
bines with the advantages of both poly(aluminum chloride) and
has the characteristics not only of aluminum
salt coagulants but also of iron salt coagulants. Specifically, alumi-
num salt coagulants [e.g., poly(aluminum chloride) (PAC) and
poly(aluminum sulphate) (PAS)] can treat a variety of water sam-
ples, have are highly efficient at turbidity removal,
and cause less
corrosion to pipelines. Iron salt coagulants [e.g., poly(ferric chlo-
ride) (PFC) and Polyferric sulphate (PFS)] have the characteristics
of quick settling, easy separation, and excellent performance in low-
temperature water treatment.
However, PAFC also requires a large
coagulant dosage and causes secondary pollution, which is a com-
mon disadvantage of inorganic flocculants. On the other hand,
although organic flocculants such as polyacrylamide (PAM) have a
lower consumption and toxicity,
the monomer acrylamide
(AM) often produces some harmful substances that may lead to
carcinogenesis, teratogenesis, and mutagenesis. Furthermore, the
expensive price of PAM limits its wide application.
Therefore, to take advantage of PAFC and PAM, these com-
pounds have been used as a composite coagulant in the field of
2018 Wiley Periodicals, Inc.
J. APPL. POLYM. SCI. 2018, DOI: 10.1002/APP.46355
46355 (1 of 9)