FIELD OF INVENTION
This invention relates to polymeric flocculants for use as a
flocculating agent, for example, for treatment of waste water.
OBJECTS OF THE INVENTION
An object of this invention is to propose graft copolymers of
polysaccharide and acrylamide and a process for the preparation
thereof for treatment of waste water.
Another object of this invention is to propose graft copolymers
of polysaccharide and acrylamide and a process for the prepara-
tion thereof for treatment of waste water which have a high shelf
life.
Still another- object of this invention is to propose graft
copolymers of polysaccharide and acrylamide and a process for the
preparation thereof for treatment of waste water which are
efficient and possess shear stability.
A further object of this invention is to propose graft copolymers
of polysaccharide and acrylamide and a process for the prepara-
tion thereof for treatment of waste water which can be used at
very low dosages.
Further objects and advantages of this invention will be more
apparent from the ensuing description.
BRIEF DESCRIPTION OF INVENTION
According to this invention, there is provided a process for the
preparation of graft copolymers for use as a flocculating agent,
comprising preparing a solution of a polysaccharide and adding a
solution of a catalyst thereto, followed by additon of an acryl-
amide solution thereto with stirring to obtain the graft
copolymer.
In accordance with this invention is provided a process for the
preparation of a graft copolymer which comprises in the step of
solution polymerization.
To a solution of the polysaccharide, preferably amylopectin is
added to the catalyst solution. The catalyst is preferably a
Ce(IV) compund such as cerric ammonium nitrate (CAN). A solution
of the polyacrylamide is added thereto with stirring to obtain
the graft copolymer.
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The polysaccharide is used in a proportion of 1 to 1.5 >s 10 in
AGU. The acrylamide is used in a proportion of 0.15 to 0.25 moles
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and the catalyst in 6 to 9 >: 10 moles.
The invention will now be explained in greater detail with the
help of the following non-limiting example.
EXAMPLE
Amount Amylopectin (Moles in ASIJ) : 1.234 x 10
Amount of Acrylamide (Moles) : 0.211
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Amount of Ce (IV) s 8.75 >; 10
A solution of amylopectin is prepared and to it is added a
solution of the catalyst. Thereafter, the solution thus obtained
is stirred and a solution of the acrylamide is added thereto. The
i o
.' reaction is carried out at 3.0 C and at atmospheric pressure to
obtain the graft copolymer. The grafting efficiency is observed
to be 85.3 and the instrinsic viscosity is 3.55.
The graft copolymer thus obtained is used for a number of floccu-
lation studies and the flocculat ion behaviour is shown in Figs.l-
7 of the accompanying drawings.
Fig.l shows the variation of supernatant turbidity with floccu—
lant dose in kaolin suspension (0.25K) in water. The comparison
is among starch, amylopectin, Ap-273 and Ap-g-PAM4;
Fig.2 shows the variation of supernatant turbidity with floccu-
lant dose in kaolin suspension (0.25%) in water. The comparison
is among Ap-g-PAMl, Sufloc, Ap-273 and Aquaset;
Fig.3 shows a trend of polymer concentration (in ppm) vs. turbi-
dity in NTU units in the course of treatment of a synthetic
effluent containing kaolin clay. The copolymer according to the
invention shows the best performance;
Fig.4 shows the results of a jar test using commercial floccu—
lants for Jamadoba (coal);
Fig.5 depicts the results of a .jar test on West Bengal washery
effluent using graft copolymer;
Fig.6 shows the jar test results for copper or thickener inflow
using graft copolymers and commercial flocculants; and
Fig.7 depicts the jar test results of commercial flocculants on
West Bengal washery effluents.
These flocculants have high flocculation efficient and shear
stability, usable at very low dosage and have controlled bio--
degradabi1ity. Thus, they have capacity of reasonably high shelf
life and ultimate biodegradation. These attributes are not
present in typical polyacrylamide based flocculating agents or
polysaccharides which are used in general. Out of various grafted
polysaccharides, the grafted amylopectin has shown the best
performance in treatment of various synthetic, industrial and
mining effluents.
WE CLAIM:
1. A process for the preparation of graft copolymers for use" as a flocculating
agent, comprising preparing a solution of amylopectin and adding a
solution of a catalyst thereto, followed by addition of an acrylamide
solution thereto with stirring to obtain the graft copolymer.
2. The process as claimed in Claim 1 wherein the temperature is conduced
at a temperature in the range of 28 to 32°C, preferably at 30°C.
3. The process as claimed in Claim 1 wherein the reaction is conducted at
atmospheric pressure.
4. The process as claimed in Claim 1 wherein the catalyst is cerric
ammonium nitrate (CAN).
amylopectin
5. The process as claimed in Claim 1 wherein the puManfthiridc is used in
a proportion of 1 to 1.5 x 10 "3 moles In AGU.
6. The process as claimed in Claim 1 wherein Vne acryiamide is used in 0.15
to 0.25 moles.
7. The process as claimed in Claim 1 wherein the catalyst is used in 6 to 9 x
10 5 moles.
8. A process for the preparation of graft copolymers for use as a flocculating
agent substantially as herein described and illustrated.

This invention relates to a process for the preparation of graft copolymers for use
as a flocculating agent, comprising preparing a solution of amylopectin and
adding a solution of a catalyst thereto, followed by addition of an acrylamide
solution thereto with stirring to obtain the graft copolymer.