POLYMER AND METHODS FOR PREPARING
AND USING THE SAME
BACKGROUND
[0001] The invention relates generally to polymers and methods for preparing and
using the polymers. In particular, the invention relates to copolymers, methods for
preparing the copolymers, and methods for using the copolymers to remove heavy
metals from aqueous solutions.
[0002] Heavy metal pollution is an existing and growing worldwide problem. For
example, waste water issuing from waste treatment facilities, from the chlor-alkali
industry, from the metal finishing industry, and from certain municipal landfills often
presents a metal contamination problem. Similarly, the metal content of water exiting
both or either of functional and abandoned mines is a significant environmental issue
in geographical areas with a mining industry.
[0003] Different treatment techniques have been developed to remove either or both
dissolved and suspended heavy metal ions from industrial waters and wastewaters.
One common practice is to precipitate the bulk of the heavy metal contaminant as its
metal hydroxide. Metal ions such as copper and lead are easily precipitated in this
way, but the minimum concentration that can be obtained is limited by the finite
solubility of the hydroxide complexes. The resulting effluent from the hydroxide
precipitation may be treated with a metal scavenging agent to remove any trace metal
contaminants to meet discharge regulations. These agents may be precipitants,
adsorbents, or metal specific ion exchange resins. The metal scavenger precipitants
may also be effective when added in the same step as the hydroxide precipitation.
Typical compounds utilized as precipitating scavenging agents include sulfides,
(thio)carbonates, alkyl dithiocarbamates, mercaptans, and polydithiocarbamates.
[0004] The prior art scavenging agents have limitations. The metal thiocarbonates,
sulfides, mercaptans, and thiocarbamates form fine floes which are not conducive to
settling and typically require the use of a flocculation agent. The metal thiocarbonates,sulfides, mercaptans, and thiocarbamates are unstable over time and under certain pH
conditions because the thiocarbonates, sulfides, mercaptans, and thiocarbamates lack
sufficient binding sites for heavy metal ions. Such unstable precipitates may release
bound metal back into the environment, thereby proving unsatisfactory as treatment or
remediation agents. Prior art polydithiocarbamates are characterized as having limited
water solubility, which limits the possible degree of functionalization. In addition, a
number of the prior art scavenging agents are themselves very toxic and care must be
taken to ensure that they are not present in the discharged wastewater.
[0005] There exists a need, therefore, for a new material to remove heavy metals from
aqueous solutions. It is desirable that this material is less toxic and forms larger, and
faster settling precipitates than the prior art compounds which remain stable over a
range of environmental conditions and over extended periods of time. It is also
desirable that this material is water-soluble so it can be utilized in existing
clarification facilities, avoiding the need for capital investment in resin-bed apparatus
or other specialized equipment. It is also desirable that this material can be prepared
easily and cheaply, and has an adequate molecular weight, chemical stability, and
high affinity for one or more heavy metal ions.
BRIEF DESCRIPTION
[0006] Embodiments of the invention include polymers and methods for preparing
and using the polymers.
[0007] In one embodiment, a polymer comprises structural units of formula
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R are independently hydrogen, or a methyl group;R is -COOH, -CONH 2 or -OH, when R is -OH, R , R and R are respectively
hydrogen; and
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen.
[0008] In another embodiment, a method comprises:
providing a polymer comprising structural units of formula
and III; and
reacting the polymer comprising the structural units of formula I and formula III
with a hydrosulfide salt or a sulfide salt to form a polymer comprising structural units
of formula wherein
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R7 are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen;
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R7 are respectively
hydrogen; and
X is halogen.
[0009] In another embodiment, a method comprises:adding an effective amount of a polymer to an aqueous solution to form
precipitates comprising at least one of heavy metals; and
removing the precipitates from the aqueous solution;
the polymer comprising structural units of formula I and
formula
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R3 and R are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen; and
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen.
DETAILED DESCRIPTION
[0010] Approximating language, as used herein throughout the specification and
claims, may be applied to modify any quantitative representation that could
permissibly vary without resulting in a change in the basic function to which it is
related. Accordingly, a value modified by a term or terms, such as "about", is not to
be limited to the precise value specified. In some instances, the approximating
language may correspond to the precision of an instrument for measuring the value.
Moreover, the suffix "(s)" as used herein is usually intended to include both the
singular and the plural of the term that it modifies, thereby including one or more of
that term.[0011] Any numerical values recited herein include all values from the lower value to
the upper value in increments of one unit provided that there is a separation of at least
2 units between any lower value and any higher value. As an example, if it is stated
that the amount of a component or a value of a process variable such as, for example,
temperature, pressure, time and the like is, for example, from 1 to 90, preferably from
20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22
to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in this specification. For values
which are less than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as
appropriate. These are only examples of what is specifically intended and all possible
combinations of numerical values between the lowest value and the highest value
enumerated are to be considered to be expressly stated in this application in a similar
manner.
[0012] In one embodiment, a polymer comprises structural units of formula
wherein
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen; and
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen.
[0013] The polymer may be random, block or graft copolymers, or a polymer having
an intermediate structure thereof, for example, a random copolymer having blocky
sequences. Orientations of individual structural units with respect to each other and
connections between individual structural units in the polymers may be head-to-head,tail-to-tail or head-to-tail. For example, if -CR4R2- and -CR5R - are heads, -CR5R 6-
may be joined to -CR1R2- or -CR3R4-.
[0014] In some embodiments, the polymer is of formula:
wherein n is an integer greater than 0, m is an
integer greater than 0, and the polymer has a molecular weight of from about 500 to
about 2,000,000.
[0015] The terms "n" and "m" used herein refer to relative total amounts (e.g.,
numbers, moles, . . .etc.) of structural units of formulas I and II in the polymer and do
not indicate the structure of the polymer. The structural units of formulas I and II may
be arranged alternately, or either of the structural units of formulas I and II may repeat
itself twice or more times in the polymer before it connects to another different
structural unit. A ratio of n to m may be in a broad range. In some embodiments, a
ratio of n to m is from about 1:99 to about 99:1, or preferably from about 10:90 to
about 90:10, or more preferably from about 30:70 to about 70:30.
[0016] Examples of monomers which the structural unit of formula I may be derived
from include but are not limited to:
HOOC =
acrylic acid , vinyl alcohol OH acrylamide CONH2
methylacrylic acid COOH an j methylacrylamide .
[0017] Examples of monomers which the structural unit of formula II may be derived
from include but are not limited to:[0018] In some embodiments, the polymer is of formula:
[0019] In some embodiments, the polymer is of formula:
in which n:m is from about 60:40 to about 70:30,
and molecular weight (Mw) of the polymer is from about 5,000 to about 100,000.
[0020] The polymer may comprise two or more different structural units derived from
monomers described above although only polymers with two different structural units
are set as examples herein.
[0021] In another embodiment, a method comprises:providing a polymer comprising structural units of formula
and
reacting the polymer comprising the structural units of formula I and formula III
with a hydrosulfide salt or a sulfide salt to form a polymer comprising structural units
of formula I and formula wherein
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R3 and R are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen;
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen; and
X is halogen.
[0022] In some embodiments, the hydrosulfide salt is sodium hydrosulfide or
potassium hydrosulfide and the sulfide salt is sodium sulfide or potassium sulfide.
[0023] In some embodiments, X is CI.
[0024] In some embodiments, the polymer comprising the formula I and the formula
III is prepared by epoxy ring opening reaction between a polymer comprising the
structural units of formula I and epichlorohydrin.[0025] In some embodiments, the polymer comprising the formula I and the formula
III is prepared by copolymerizing a monomer of formula with a
monomer of formula
[0026] In some embodiments, the monomer of formula is
prepared by epoxy ring opening reaction between the monomer of formula
R4 R2
R R and epichlorohydrin.
[0027] In another embodiment, a method comprises: adding an effective amount of a
polymer to an aqueous solution to form precipitates comprising at least one of heavy
metals; and removing the precipitates from the aqueous solution; the polymer
comprising structural units of formula I and formula II, wherein R1, R2, R5 and R6 are
independently hydrogen, a methyl group, or -COOH, only one of R1 and R2 or R5 and
R6 is -COOH; R3 and R are independently hydrogen, or a methyl group; R4 is -
COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively hydrogen;
and R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen.
[0028] The heavy metals may be any heavy metals existing in any forms that need to
and may be removed by the polymer of the present invention, such as aluminium (Al),
arsenic (As), beryllium (Be), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium
(Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), molybdenum (Mo),nickel (Ni), lead (Pb), plutonium (Pu), tin (Sn), thorium (Th), thallium (Tl), uranium
(U), vanadium (V), tungsten (W), zirconium (Zr), and zinc (Zn). In some
embodiments, the heavy metals comprise at least one of chromium (Cr), copper (Cu),
zinc (Zn), lead (Pb), cobalt (Co), cadmium (Cd), and nickel (Ni).
[0029] The polymer may be added alone or in combination with other additives.
Examples of other additives include but are not limited to inorganic or polymer
flocculants. The amount of the polymer added may vary according to the application
environment, e.g., the amount and type of heavy metals to be removed and effects of
other materials coexisting with heavy metals in the aqueous solutions. In some
embodiments, a concentration ratio by weight of each of the at least one of the heavy
metals to the polymer in the aqueous solution is from about 5:1 to about 1:100, or
preferably from about 1:1 to about 1:50, or more preferably from about 1:5 to about
1:20.
[0030] Examples of polymers that may be added alone or in combination with each
other include, but are not limited to:
[0031] In some embodiments, the polymer is of formula:, or , in which n:m is from about 60:40 to about 70:30,
and the polymer has a Mw of from about 5,000 to about 100,000.
[0032] The precipitates may be removed by any suitable ways. In some embodiments,
the removing is by filtering the precipitates from the aqueous solution or by
sedimentation.
EXAMPLES
[0033] The following examples are included to provide additional guidance to those
of ordinary skill in the art in practicing the claimed invention. Accordingly, these
examples do not limit the invention as defined in the appended claims.
[0034] Acrylic acid, acrylamide, methylacrylamide, methacrylic acid, hydrochloric
acid (37% solution), epichlorohydrin, potassium hydroxide, sodium hydroxide,
ethanol and isopropanol were from Sinopharm Chemical Reagent Co., Ltd., Shanghai,
China. Poly(acrylic acid) (Mw: about 1800), poly(vinyl alcohol) (average Mw
13,000-23,000, 98% hydrolyzed), sodium hydrosulfide (NaHS-¾0) and sodium
persulfate ( a2S20s) were from Aldrich Chemical Co., Milwaukee, WI, USA.
Chemicals were used without further purification, unless specified otherwise. Atomic
absorption Spectrometer (AA)/inductively coupled plasma (ICP) standard solutions of
chromium (Cr), copper (Cu), zinc (Zn), lead (Pb), cobalt (Co), cadmium (Cd),
selenium (Se), boron (B) and nickel (Ni) were obtained from Shanghai Analytical
Center, at concentrations of from 1,000 ppm to 10,000 ppm. Each of the ICP standard
solutions comprises 2- 10% (by weight) of nitric acid.
[0035] Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker
Avance™ 400 ( H & 1 C, 400 MHz) spectrometer and referenced versus residual
solvent shifts.[0036] Molecular weights were determined using gel permeation chromatography
(GPC) analyses performed at 40 °C using an apparatus equipped with a Waters 590
pump and a Waters 717- plus injector. A differential refractometry (Waters R410)
was used for detection. The column set were Shodex SB-805 HQ/ SB-804 HQ with
SB-G guard column. The eluent was the aqueous solution of 0.1 mol/1 a C and
0.02% by weight a and had a flow rate of 0.5 mL/min. Calibration was performed
using polyacrylic acid sodium salt (Mp 2,925- 782,200). The software used for data
acquisition, calibration and treatment was Cirrus™ multidetector GPC software.
EXAMPLE 1: Synthesis of poly(acrylic acid)
[0037] To a 100 mL three-necked round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 50 g of deionized water and 0.25 g of
sodium metabisulfite ( a2S206, 1.22 mmol). The solution was heated to 60 °C. Then
an aqueous solution of acrylic acid (10 g, 0.138 mol) and sodium persulfate (0.125 g,
0.52 mmol) was charged dropwise over 30 minutes under nitrogen atmosphere. Upon
completion of the addition, the reaction mixture was heated to 70 °C for 90 minutes
and was then cooled to room temperature. The pH of the resulting solution was
measured to be about 3. The structure of the resulting polymer was verified by H
NMR. H NMR (δ, D20 ) 2.21 (br, 1H), 1.75-1.43 (br, 2H). Mw: 5521, PD
(polydispersity): 2.7.
EXAMPLE 2 : Esterification of poly(acrylic acid) with epichlorohydrin[0038] To a 100 n L three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 20 g of deionized water and 4 g (55.6
mmol) of poly(acrylic acid) obtained from example 1. Epichlorohydrin (EPI, 6.172 g,
66.8 mmol) and potassium hydroxide (72 mg) were added while stirring and being
cooled by the ice water for 30 minutes. The obtained solution was heated to 90 °C for
4 hours and was then cooled to the room temperature. The structure of the resulting
copolymer (Mw=5521) was verified by H NMR as evidenced by the peaks between
the region of 1-4.5 ppm, H NMR (δ, D20 ) 1.64-2.38 (br, 3 H), 3.63 (br, 1.33 H), 3.88
(br, 0.65H), 4.12 (br, 1.4H). The structure of the resulting copolymer was also verified
by 1 C NMR as evidenced by the peaks between the region of 170-190 ppm,
1 C
NMR (δ, D20 ) 176 (br, 1.04H), 179 (br, 1H).
EXAMPLE 3 : Synthesis of poly(acrylic acid) with 2-hydroxy-3-mercaptopropoxy
pendant group
[0039] To a 50 mL round bottom flask was charged 10 g of deionized water and the
copolymer (3.46 g, 27.8 mmol) obtained in example 2. Then the pH of the solution
was adjusted to about 7 using NaOH. The solution was added to a buffer solution of
sodium hydrosulfide (3 g, 40 mmol, pH: 8.0) dropwise for over 30 minutes. Theobtained solution was heated to 40 °C for 2 hours and was then allowed to cool to the
room temperature. The structure of the resulting copolymer (m:n=3:7) was verified by
H NMR as evidenced by the peaks between the region of 0-4.5 ppm, ¾ NMR (δ,
D20 ) 1.54-2.38 (br), 2.62-2.85 (br), 3.62-4.17 (br).
EXAMPLE 4 : Esterification of acrylic acid
[0040] To a 25 mL three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 2.1 g (29 mmol) of acrylic acid. Then
epichlorohydrin (EPI, 1.34 g, 14.5 mmol) and potassium hydroxide (30 mg) were
added. While sparging with nitrogen, the solution was heated to 85 °C for 4 hours.
Then the solution was cooled to the room temperature. The structure of the resulting
3-chloro-2-hydroxypropyl acrylate was verified by 1 C NMR as evidenced by the
peaks between the region of 160-180 ppm, C NMR (δ, D20 ) 168 (br, 0.98H), 170
(br, 1H).
EXAMPLE 5 : Copolymerization of acrylic acid with 3-chloro-2-hydroxypropyl
acrylate
[0041] To a 25 mL three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 10 g of deionized water. Sodiumpersulfate (0.32 g) and 1.1 g of a mixture (ratio: 1:1) of 3-chloro-2-hydroxypropyl
acrylate and acrylic acid were added dropwise for over 30 minutes at 80 °C. The
solution was maintained at 80 °C for 3 hours and was then cooled to the room
temperature. The pH of the solution was adjusted to about 7 using sodium hydroxide.
Then the solution was added to the solution of sodium hydrosulfide (0.68 g, 9.1
mmol, in a pH 8.0 buffer solution) dropwise for over 30 minutes. The solution was
heated to 40 °C for 2 hours. Then the solution was allowed to cool to the room
temperature and added to 100 ml of ethanol to get precipitates of the resulting
copolymer (m:n=3:7, Mw=50,224), the structure of which was verified by H NMR as
evidenced by the peaks between the region of 0-4.5 ppm, H NMR (δ, D20 ) 1.45-2.4
(br), 3.68 (br), 4.16 (br).
EXAMPLE 6 : Synthesis of the polyacrylamide
[0042] To a 50 mL three-necked round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 20 g of deionized water and 114 mg
of sodium metabisulfite ( a2S20 6) . The solution was heated to 50 °C. An aqueous
solution comprising acrylamide (2.85 g, 40 mmol) and sodium persulfate (57 mg) was
added dropwise for over 15 minutes under nitrogen atmosphere. Upon completion of
the addition, the solution was heated to 60 °C for 90 minutes and then cooled to the
room temperature. The structure of obtained poly(acrylamide) was verified by
1HNMR. ¾ NMR (δ, D20 ) 2.23 (br, 1H), 1.65 (br, 2H).
EXAMPLE 7 : Epoxy ring opening reaction between polyacrylamide and
epichlorohydrin[0043] To a 25 n L three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 10 g of deionized water. Then 0.77g
of polyacrylamide (10.83 mmol) and EPI (0.75 g, 8.12 mmol) were added. Adjusted
the pH of the solution to about 10, and heated the solution to 60 °C for 3 hours. The
solution was then cooled to the room temperature, and charged to a solution of
sodium hydrosulfide (0.7 g, 9.6 mmol, in a pH 8.0 buffer solution) dropwise for over
30 minutes. The obtained solution was heated to 40 °C for 2 hours and was allowed to
cool to the room temperature. The resulting copolymer (m:n=4:6) was precipitated
using 150 ml of ethanol and the structure of the resulting copolymer was verified by
H NMR as evidenced by the peaks between the region of 0-4.5 ppm, ¾ NMR (δ,
D20 ) 1.5 (br), 2.18 (br), 2.7 (br), 3.6-4.02(br).
EXAMPLE 8 : Synthesis of polyacrylamide with 2-hydroxy-3-mercaptopropoxy
pendant group
[0044] To a 25 mL three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 10 g of deionized water. Acrylamide
( 1 g, 14.1 mmol) and EPI (1.04 g, 11.28 mmol) were added into the deionized water.
The pH of the solution was adjusted to about 10, and the solution was heated to 60 °Cfor 3 hours. After the solution was cooled to the room temperature, 114 mg of sodium
metabisulfite (Na2S206) was added. The solution was heated to 50 °C before an
aqueous solution comprising acrylamide (0.72 g, 10 mmol) and sodium persulfate (57
mg) was charged dropwise for over 15 minutes under nitrogen atmosphere. Upon
completion of the addition, the solution was heated to 80 °C for 90 minutes. The
solution was cooled to the room temperature, and was added to a buffer solution of
sodium hydrosulfide (1.41 g, 13.5 mmol, pH=8.0) dropwise for over 30 minutes. The
obtained solution was heated to 40 °C for 2 hours and was allowed to cool to the room
temperature. The resulting copolymer (m:n=2.5:7.5) was precipitated from 100 ml
ethanol and the structure was verified by NMR as evidenced by the peaks between
the region of 0-4.5 ppm, ¾ NMR (δ, D20 ) 1.5 (br), 2.18 (br), 2.7 (br), 3.6-4.02(br).
EXAMPLE 9 : Synthesis of poly(vinyl alcohol) with 2-hydroxy-3-mercaptopropoxy
pendant group
[0045] To a 50 mL of three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 15 g of tetrahydrofuran (THF) and 1 g
(22.7 mmol) of polyvinyl alcohol) (Mw 13,000-23,000). Epichlorohydrin (0.84 g, 9.1
mmol) and potassium hydroxide (9.2 mg) were charged and stirred for 30 minutes.
The obtained solution was heated to 70 °C under reflux for 4 hours and was then
cooled to the room temperature. The solution was charged to a solution of sodium
hydrosulfide (NaHS -
H20 ) (0.81 g, 11 mmol in 10 g deionized water) dropwise in 30
minutes. The solution was heated to 40 °C for 2 hours and was then allowed to cool to
the room temperature. The structure of the resulting polymer (m:n=2:8, Mw 13,000-
23,000) in the solution was verified by H NMR as evidenced by the peaks between
the region of 0-4.5 ppm, H NMR (δ, DMSO) 1.37 (br), 1.93 (br), 2.75 (br), 3.62-4.17
(br).EXAMPLE 10: Synthesis of poly (methylacrylamide) with 2-hydroxy-3-
mercaptopropoxy pendant group
[0046] To a 50 mL three-neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 20 g of deionized water and 114 mg
of sodium metabisulfite ( a2S20 6) . The solution was heated to 70 °C. Then an
aqueous solution comprising methylacrylamide (3.4 g, 40 mmol) and sodium
persulfate (57 mg) was charged dropwise for over 15 minutes under nitrogen
atmosphere. Upon completion of the addition, the mixture was heated to 60 °C for 90
minutes and was then cooled to the room temperature. The structure of the resulting
polymer (poly(methylacrylamide)) in the solution was verified by NMR (δ, D20 )
1.33 (br, 3H), 1.65 (br, 2H).
[0047] Poly(methylacrylamide) (obtained above, 0.91 g, 10.83 mmol) was charged to
a 25 mL three neck round bottom flask equipped with a thermometer, a nitrogen inlet
and an addition inlet. Deionized water (10 g) and EPI (0.75g, 8.12mmol) were then
charged. The pH of the solution was adjusted to about 10 with sodium hydroxide. The
solution was heated to 60 °C for 3 hours and was then cooled to the room temperature.
The solution was charged to a buffer solution of sodium hydrosulfide (0.7 g, 9.6
mmol, pH 8.0) dropwise for over 30 minutes. The obtained solution was heated to 40
°C for 2 hours and was then allowed to cool to the room temperature. The resulting
copolymer (m:n=4:6) was precipitated using ethanol (150 ml) and the structure of the
copolymer was verified by NMR as evidenced by the peaks between the region of
0-4.5 ppm, H NMR (δ, D20 ) 1.32 (br), 1.5 (br), 2.7 (br), 3.6-4.02(br).
EXAMPLE 11: Esterification of methacrylic acid (3-chloro-2-hydroxypropyl
methacrylate)KOH/90 °C
[0048] To a 25 n L three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 2 g (23.23 mmol) of methacrylic acid.
Epichlorohydrin (0.86 g, 9.3 mmol) and potassium hydroxide (14.3 mg) were charged.
While sparging with nitrogen, the solution was heated to 90 °C for 4 hours and was
then cooled to the room temperature. The structure of the resulting product was
verified by H NMR as evidenced by the peaks between the region of 1-7 ppm, H
NMR (δ, D20 ) 2.02 (s, 3H), 3.5 (m, 2 H), 4.05-4.5 (br, 3H), 6.50 (m, 2H).
EXAMPLE 12: Synthesis of poly(methacrylic acid) with 2-hydroxy-3-
mercaptopropoxy pendant group
[0049] To a 25 mL three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 10 g of deionized water, then sodium
persulfide (0.32 g) and 1.5 g of a mixture of 3-chloro-2-hydroxypropyl methacrylate
and methacrylic acid (1:1) were charged dropwise for over 30 minutes at 80 °C. The
solution was maintained at 80 °C for 3 hours before it was cooled to room temperature.
PH of the solution was adjusted to 7 with sodium hydroxide. The solution was then
charged to a buffer solution of sodium hydrosulfide (0.75 g, 10 mmol, pH 8.0)
dropwise for over 30 minutes. The obtained solution was heated to 40 °C for 2 hours
and was allowed to cool to the room temperature. The resulting copolymer (m:n=3:7)
was precipitated using 100 ml ethanol and the structure of the copolymer was verified
by H NMR as evidenced by the peaks between the region of 0-4.5 ppm, H NMR (δ,
D20 ) 1.34 (br), 1.55(br), 2.50-3.12 (br), 3.68 (br), 4.16 (br).EXAMPLE 13: Synthesis of copolymer of acryamide and 3-thiol-2-hydroxypropyl
acrylate
[0050] To a 25 mL three neck round bottom flask equipped with a thermometer, a
nitrogen inlet and an addition inlet was charged 10 g of deionized water, then 1.1 g
mixture of 3-chloro-2-hydroxypropyl acrylate and acrylamide (1:1) and sodium
persulfide (0.32 g) were charged dropwise over 30 minutes at 80°C, then the solution
was maintained at 80 °C for 3 hours. The mixture was cooled to room temperature;
pH was adjusted to 7 with sodium hydroxide. Then the mixture solution was charged
to the solution of sodium hydrosulfide (0.68 g, 9.1 mmol, in pH 8.0 buffer solution)
dropwise over 30 minutes, the solution was heated to 40 °C for 2 hours. Then the
reaction was allowed to cool to room temperature. The resulting copolymer
(m:n=3.5:6.5) was precipitated from ethanol and the structure was verified by H
NMR as evidenced by the peaks between the region of 0-4.5 ppm, ¾ NMR (δ, D20 )
1.45-2.4 (br), 2.51-3.12 (br), 3.68 (br), 4.16 (br).
EXAMPLE 14: Heavy metal removal tests:
[0051] In this experiment, the apparatuses include beakers (500 ml), a Phipps and
Bird ™jar tester with six standard paddles, a pH meter, plastic syringes, 0.45 micron
filters and glass sample bottles.
[0052] Firstly, 9 atomic absorption Spectrometer (AA)/ Inductive Coupled Plasma-
mass Spectrometer (ICP) single element standard solutions respectively comprising
Cd, Cr, Cu, Se, Pb, i, B, Co, and Zn were added into deionized water in a plastic
beaker (5L) to prepare 3 L of a stock solution.
[0053] The pH of the stock solution was adjusted to specified values. A sample of the
stock solution (5 ml) was taken for an ICP analysis using an ICP-OES (Inductivelycoupled plasma optical emission spectrometry) analyzer (Spectro Ciros, SPECTRO
Analytical Instruments GmbH, Cleves, Germany). The stock solution was added into
six clean 500 ml beakers respectively (400 ml/beaker) in the jar tester. A given
amount of the polymer were added into the beaker so that the concentration of the
polymer in the stock solution was 9 ppm, 45 ppm or 90 ppm as shown in tables
below. The polymer dosage was calculated based on weight of polymer added into the
stock solution, e.g., 1 ppm means 1 mg of polymer were dosed into 1 L of stock
solution. The obtained mixture was stirred at 100 rpm for 2 minutes, at 35 rpm for 5
minutes, and left settling for 5 minutes.
[0054] A sample (5 ml) of the supernate in the beaker was taken after settling for an
ICP analysis. Another sample (5 ml) of the supernate was taken from the beaker to be
filtered through a 0.45 micron filter. An ICP analysis of the filtrate was conducted.
[0055] Table 1 below shows the ICP analysis result (concentration) of each of Cr, Cu,
Zn, Pb, Co, Cd and Ni in the stock solution (pH=9.15), the supernate, and the filtrate
and the reduction rate of each of Cr, Cu, Zn, Pb, Co, Cd and Ni after being treated by
different concentrations (shown in table 1 below) of polymer obtained in example 3
and being filtered. The reduction rate was calculated by this formula: reduction rate
(%)=(concentration of stock solution-concentration of supernate or
filtrate)/concentration of stock solution x 100.
Table 1:concentration (ppm) 0.82 0.24 0.20 0.54 0.25 0.57 0.29
supernate
reduction rate (%) 5.74 79.58 82.14 41.17 78.98 28.63 76.44
45 ppm
concentration (ppm) 0.81 0.07 0.07 0.30 0.12 0.41 0.18
filtrate
reduction rate (%) 6.5 94.13 93.72 67.62 89.65 49.31 85.46
concentration (ppm) 0.83 0.66 0.58 0.93 0.63 0.77 0.71
supernate
reduction rate (%) 4.59 43.71 48.69 -1.21 46.56 4.32 42.42
90 ppm
concentration (ppm) 0.80 0.09 0.09 0.36 0.16 0.39 0.27
filtrate
reduction rate (%) 8.28 92.08 91.95 61.36 86.01 51.29 77.95
[0056] Table 2 below shows the ICP analysis result (concentration) of each of Cr, Cu,
Zn, Pb, Co, Cd and Ni in the stock solution (pH=9), the supernate and the filtrate and
the reduction rate of each of Cr, Cu, Zn, Pb, Co, Cd and Ni after being treated by
different concentrations (shown in table 2 below) of polymer obtained in example 5
and being filtered.
Table 2concentration (ppm) 1.12 0.15 0.14 0.26 0.13 0.28 0.16
supernate
reduction rate (%) 5.8 88.4 88.5 78.51 88.59 75.52 86.31
90 ppm
concentration (ppm) 1.12 0.08 0.19 0.20 0.04 0.20 0.08
filtrate
reduction rate (%) 6.24 94.27 84.19 83.53 95.99 82.49 92.95
[0057] It can be seen from tables 1 and 2 above, after being treated by the polymers,
the concentration of each of Cr, Cu, Zn, Pb, Co, Cd and Ni in the solution (supernate
and filtrate) was reduced compared with in the stock solution. For most of Cr, Cu, Zn,
Pb, Co, Cd and Ni, the removal efficiency in table 1 was lower than that in table 2.
Further more, the residues of Cr, Cu, Zn, Pb, Co, Cd and Ni in the supernate and
filtrate solutions were acceptable and close to each other since the removal
efficiencies in table 2 were close, which suggests that filtration may be possibly
omitted where filtration is undesirable.
[0058] While only certain features of the invention have been illustrated and
described herein, many modifications and changes will occur to those skilled in the
art. It is, therefore, to be understood that the appended claims are intended to cover
all such modifications and changes as fall within the true spirit of the invention.CLAIMS:
1. A polymer comprising structural units of formula and
formula wherein
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R7 are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen; and
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen.
2. The polymer of claim 1, being of formula:
wherein n is an integer greater than 0, m is an
integer greater than 0, and the polymer has a molecular weight of from about 500 to
about 2,000,000.
3. The polymer of claim 2, wherein a ratio of n to m is from about 1:99 to about
99:1.
4. The polymer of claim 2, wherein a ratio of n to m is from about 10:90 to about
90:10
5. The polymer of claim 2, wherein a ratio of n to m is from about 30:70 to about
70:30
6. The polymer of claim 2, being of formula:7. The polymer of claim 1, being of formula:
, or wherein n:m is from about 60:40 to about 70:30,
and the polymer has a Mw of from about 5,000 to about 100,000.
8. A method comprising:
providing a polymer comprising structural units of formula
and formula andreacting the polymer comprising the structural units of formula I and formula III
with a hydrosulfide salt or a sulfide salt to form a polymer comprising structural units
of formula I and formula
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R7 are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH 2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen;
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R are respectively
hydrogen; and
X is halogen.
9. The method of claim 8, wherein the hydrosulfide salt is sodium hydrosulfide
or potassium hydrosulfide and the sulfide salt is sodium sulfide or potassium sulfide.
10. The method of claim 9, wherein X is CI.
11. The method of claim 8, wherein the polymer comprising the formula I and the
formula III is prepared by epoxy ring opening reaction between a polymer comprising
the structural units of formula I and epichlorohydrin.13. The method of claim 12, wherein the mornomer of formula
is prepared by epoxy ring opening reaction between the monomer of formula
R4 R2
R R and epichlorohydrin.
14. A method, comprising:
adding an effective amount of a polymer to an aqueous solution to form
precipitates comprising at least one of heavy metals; and
removing the precipitates from the aqueous solution;
the polymer comprising structural units of formula I and
formula w e
rein
R1, R2, R5 and R6 are independently hydrogen, a methyl group, or -COOH, only
one of R1 and R2 or R5 and R6 is -COOH;
R and R are independently hydrogen, or a methyl group;
R4 is -COOH, -CONH2 or -OH, when R4 is -OH, R1, R2 and R3 are respectively
hydrogen; and
R8 is -COO, -CONH, or -0-, when R8 is -0-, R5, R6 and R7 are respectively
hydrogen.
15. The method of claim 14, wherein the polymer is of formula:, wherein n is an integer greater than 0, m is an
integer greater than 0, and the polymer has a molecular weight of from about 500 to
about 2,000,000.
16. The method of claim 15, wherein a ratio of n to m is from about 1:99 to about
99:1.
17. The method of claim 16, wherein the heavy metals comprise at least one of
chromium (Cr), copper (Cu), zinc (Zn), lead (Pb), cobalt (Co), cadmium (Cd), and
nickel (Ni).
18. The method of claim 17, wherein the polymer is of formula
, wherein n:m is from about 60:40 to about 70:30,
and the polymer has a Mw of from about 5,000 to about 100,000.
19. The method of claim 18, wherein a concentration ratio by weight of each of
the at least one of the heavy metals to the polymer in the aqueous solution is from
about 5:1 to about 1:100.
20. The method of claim 18, wherein a concentration ratio by weight of each of
the at least one of the heavy metals to the polymer in the aqueous solution is from
about 1:1 to about 1:50.
21. The method of claim 18, wherein a concentration ratio by weight of each of
the at least one of the heavy metals to the polymer in the aqueous solution is from
about 1:5 to about 1:20.
22. The method of claim 18, wherein the removing is by filtering the precipitates
from the aqueous solution.