U.S. patent application number 11/873961 was filed with the patent office on 2009-04-23 for controlled release remediation system and composition.
Invention is credited to Stephanie Luster-Teasley.
Application Number | 20090105371 11/873961 |
Document ID | / |
Family ID | 40564089 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090105371 |
Kind Code |
A1 |
Luster-Teasley; Stephanie |
April 23, 2009 |
CONTROLLED RELEASE REMEDIATION SYSTEM AND COMPOSITION
Abstract
A controlled release remediation composition or compositions, a
method making such composition(s), a method of using such
composition(s), and a remediation system including such
composition(s) are disclosed. The disclosed controlled release
remediation composition or compositions include at least one
chemical oxidant agent, optionally, at least two chemical oxidant
agents; at least one encapsulant polymer; and, optionally, at least
one matrix polymer. The disclosed controlled release remediation
composition or compositions are capable of substantially constantly
releasing an amount of the at least one chemical oxidant agent,
optionally, amounts of the at least two chemical oxidant agents,
for example, into an aqueous system such as may be found at a
contaminated site, over at least about a one month period up to
over about a three month period.
Inventors: |
Luster-Teasley; Stephanie;
(Greensboro, NC) |
Correspondence
Address: |
SMITH MOORE LEATHERWOOD LLP
P.O. BOX 21927
GREENSBORO
NC
27420
US
|
Family ID: |
40564089 |
Appl. No.: |
11/873961 |
Filed: |
October 17, 2007 |
Current U.S.
Class: |
523/124 |
Current CPC
Class: |
B09C 1/08 20130101; B09C
1/002 20130101 |
Class at
Publication: |
523/124 |
International
Class: |
C08J 3/20 20060101
C08J003/20 |
Claims
1. A controlled release remediation composition comprising: A) at
least one chemical oxidant agent, wherein the at least one chemical
oxidant agent is capable of remediating at least one chemical
pollutant; B) an encapsulant polymer, wherein: i) at least a
portion of the encapsulant polymer encapsulates at least a portion
of the chemical oxidant agent, and ii) at least a portion of the
encapsulant polymer comprises at least one of an environmentally
degradable polymer, a biodegradable polymer, or an environmentally
degradable polymer and biodegradable polymer; and C) a matrix
polymer, wherein: i) at least a portion of the matrix polymer
embeds at least a portion of the encapsulated chemical oxidant
agent, and ii) at least a portion of the matrix polymer comprises
at least one of an environmentally degradable polymer, a
biodegradable polymer, or an environmentally degradable polymer and
biodegradable polymer, Wherein the controlled release remediation
composition is capable of substantially constantly releasing an
amount of the at least one agent chemical oxidant agent into an
aqueous system over least about a one month period up to over about
a three month period.
2. The controlled release remediation composition according to
claim 1, wherein the composition comprises at least one pellet.
3. The controlled release remediation composition according to
claim 2, wherein the at least one pellet comprises one of more
dimensions ranging from about a micron (.mu.m) to multiple tens of
millimeters (mm).
4. The controlled release remediation composition according to
claim 3, wherein the at least one pellet comprises a largest
dimension of about 1 millimeter (mm, about -18 mesh), optionally
between about 500 microns (.mu.m) and about 1.0 .mu.m (about -35,
+1000 mesh), and optionally between about 300 microns (.mu.m) and
about 1.0 .mu.m (about -50, +635 mesh).
5. The controlled release remediation composition according to
claim 1, wherein the at least one pellet comprises any one of a
sphere, a cylinder, a wagon wheel, gear-shape, a saddle, a disk, a
brick, a coil, a column, a hollow-elbow, a chip, a fiber, or any
two or more of the preceding.
6. The controlled release remediation composition according to
claim 1, wherein the at least one chemical oxidant agent comprises
at least one of a photo-oxidants agent, an electron transfer
reaction agent, a free radical agent, or combinations of any two or
more of the preceding.
7. The controlled release remediation composition according to
claim 1, wherein the at least one chemical oxidant agent comprises
at least one of a persulfate agent, a permanganate agent, or
combinations of any two or more of the preceding.
8. The controlled release remediation composition according to
claim 1, wherein the at least one chemical oxidant agent comprises
at least one of a titanium oxide agent, a molybdenum sulfide agent,
a molybdenum sulfide agent, zinc sulfide agent, a sodium
permanganate agent, a potassium permanganate agent, sodium
persulfate agent, ammonium persulfate agent, potassium persulfate
agent, or a combination of any two or more of the preceding.
9. The controlled release remediation composition according to
claim 1, wherein the matrix polymer comprised a degradation rate
less that the release rate of the at least one chemical oxidant
agent and greater than the encapsulant degradation rate the at
least one encapsulant polymer.
10. The controlled release remediation composition according to
claim 1, further comprising at least one additional encapsulant
polymer, wherein at least a portion of the at least one additional
encapsulant polymer encapsulates at least a portion of the matrix
polymer embedding at least a portion of the encapsulated chemical
oxidant agent.
11. The controlled release remediation composition according to
claim 1, wherein the environmentally degradable polymer or the
biodegradable polymer comprises at least one of a polylactide, a
polyglycolide, a polylactide-co-glycolide, a polylactic acid,
polyglycolic acid, polylactic acid-co-glycolic acid, a
polycaprolactone, a polycarbonates, a polyesteramides, a
polyanhydrides, a polyamino acid, a polyorthoester, a polyacetyls,
a polycyanoacrylates, polyetheresters, a polydioxanone , a
polyalkylen alkylate, a copolymer of a polyethylene glycol and a
polylactid or polylactide-co-glycolide, a biodegradable
polyurethane, a polysaccharide, a blend of any two or more of the
preceding, or a copolymer of any two or more of the preceding.
12. The controlled release remediation composition according to
claim 11, wherein the blend comprises: b1) between 0 wt % to about
100 wt % of a first polymer; b2) between 0 wt % to about 60 wt % of
a second polymer; and b3) a balance of a third polymer.
13. The controlled release remediation composition according to
claim 11, wherein the copolymer comprises: c1) between 0 wt % to
about 100 wt % of a first polymer; c2) between 0 wt % to about 60
wt % of a second polymer; and c3) a balance of a third polymer.
14. The controlled release remediation composition according to
claim 1, wherein the environmentally degradable polymer or the
biodegradable polymer comprises at least one of a polylactic acid,
polyvinyl alcohol, polycaprolactone, a blend of any two or more of
the preceding, or a copolymer of any two or more of the
preceding.
15. The controlled release remediation composition according to
claim 14, wherein the blend comprises: b11) between 0 wt % to about
60 wt % of a polylactic acid; b12) between 0 wt % to about 60 wt %
of a polyvinyl alcohol; and b13) between 0 wt % to about 100 wt %
of a polycaprolactone.
16. The controlled release remediation composition according to
claim 14, wherein the copolymer comprises: c11) between 0 wt % to
about 100 wt % of a polycaprolactone c12) between 0 wt % to about
60 wt % of a polyvinyl alcohol; and c13) a balance of at least one
of a polylactide, a polyglycolide, a polylactide-co-glycolide, a
polylactic acid, polyglycolic acid, polylactic acid-co-glycolic
acid, a polycarbonates, a polyesteramides, a polyanhydrides, a
polyamino acid, a polyorthoester, a polyacetyls, a
polycyanoacrylates, polyetheresters, a polydioxanone, a polyalkylen
alkylate, a copolymer of a polyethylene glycol and a polylactid or
polylactide-co-glycolide, a biodegradable polyurethane, a
polysaccharide, a blend of any two or more of the preceding, or a
copolymer of any two or more of the preceding.
17. The controlled release remediation composition according to
claim 1, wherein the at least one chemical pollutant comprises at
least one of a chlorinated organic compound, a compound containing
at least one unsaturated carbon-carbon bond, an aromatic
hydrocarbon, a polycyclic aromatic hydrocarbon, a munitions
constituent, an organic pesticide, wastewater, a drinking water
treatment, a pathogen, or any combination of two or more of the
preceding.
18. The controlled release remediation composition according to
claim 1, wherein: .alpha.) the at least one chemical oxidant agent
comprises between about 1 wt % to about 60 wt % of the controlled
release remediation composition; .beta.) encapsulant polymer
comprises between about 1 wt % to about 99 wt % of the controlled
release remediation composition; and .gamma.) matrix polymer
comprises the balance of the controlled release remediation
composition.
19. The controlled release remediation composition according to
claim 1, wherein the at least one chemical oxidant agent comprises
a particle size comprising about 125 .mu.m (-120 mesh), optionally
between about 75 microns (.mu.m) and about 1.0 .mu.m (About -200,
+1000 mesh), and optionally between about 50 microns (.mu.m) and
about 1.0 .mu.m (about -270, +1000 mesh).
20. A method of making controlled release remediation composition,
the method comprising the steps of: A) selecting at least one
chemical oxidant agent capable of remediating at least one chemical
pollutant; B) selecting an encapsulant polymer that is
substantially compatible with the at least one chemical oxidant
agent and comprises at least one of an environmentally degradable
polymer, a biodegradable polymer, or an environmentally degradable
polymer and biodegradable polymer; C) encapsulating at least a
portion of the chemical oxidant agent using the encapsulant
polymer; D) selecting a matrix polymer comprising at least one of
an environmentally degradable polymer, a biodegradable polymer, or
an environmentally degradable polymer and biodegradable polymer;
and E) combining the encapsulated chemical oxidant agent and the
matrix polymer so that at least a portion of the matrix polymer
embeds at least a portion of the encapsulated chemical oxidant
agent.
21. A remediation system comprising: A) at least one controlled
release remediation composition comprising: i) at least one
chemical oxidant agent, wherein the at least one chemical oxidant
agent is capable of remediating at least one chemical pollutant;
ii) an encapsulant polymer, wherein: a) at least a portion of the
encapsulant polymer encapsulates at least a portion of the chemical
oxidant agent, and b) at least a portion of the encapsulant polymer
comprises at least one of an environmentally degradable polymer, a
biodegradable polymer, or an environmentally degradable polymer and
biodegradable polymer; and iii) a matrix polymer, wherein: a) at
least a portion of the matrix polymer embeds at least a portion of
the encapsulated chemical oxidant agent, and b) at least a portion
of the matrix polymer comprises at least one of an environmentally
degradable polymer, a biodegradable polymer, or an environmentally
degradable polymer and biodegradable polymer; and B) an amount of
at least one controlled release remediation composition capable of
being provided such that the remediation product is capable of
substantially constantly releasing a sufficient amount of the at
least one chemical oxidant agent into a contaminated site over at
least about a one month period up to over about a three month
period so as to remediate at least a portion of the at least one
chemical pollutant.
22. A method of using a controlled release remediation composition,
the method comprising the steps of: A) determining at least one
chemical pollutant to be remediated at a contaminated site; B)
selecting at least one chemical oxidant agent capable of
remediating the at least one chemical pollutant; C) selecting an
encapsulant polymer that is substantially compatible with the at
least one chemical oxidant agent and comprises at least one of an
environmentally degradable polymer, a biodegradable polymer, or an
environmentally degradable polymer and biodegradable polymer; D)
encapsulating at least a portion of the chemical oxidant agent
using the encapsulant polymer; E) selecting a matrix polymer
comprising at least one of an environmentally degradable polymer, a
biodegradable polymer, or an environmentally degradable polymer and
biodegradable polymer; F) combining the encapsulated chemical
oxidant agent and the matrix polymer so that at least a portion of
the matrix polymer embeds at least a portion of the encapsulated
chemical oxidant agent to form a controlled release remediation
composition; G) shaping, sizing, or shaping and sizing the
controlled release remediation composition so as to be capable of
substantially constantly releasing an amount of the at least one
chemical oxidant agent into an aqueous system from over at least
about a one month period up to over about a three month period; and
H) providing a sufficient amount of the shaped, sized, or shaped
and sized controlled release remediation composition to the
contaminated site in manner that remediates at least a portion of
the at least one chemical pollutant at the contaminated site.
23. A controlled release remediation composition comprising: A) a
plurality of chemical oxidant agents, wherein at least two of the
plurality chemical oxidant agents are capable of remediating at
least two different chemical pollutants; and B) a polymer, wherein:
i) at least a portion of the polymer encapsulates at least a
portion of the plurality of chemical oxidant agents, and ii) at
least a portion of the polymer comprises a biodegradable polymer.
Wherein the controlled release remediation composition is capable
of substantially constantly releasing amounts of the at least two
of the plurality chemical oxidant agents into an aqueous system
from over at least a one month period up to over about a three
month period.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a controlled release
remediation system including at least one controlled release
remediation composition. Also, the present invention relates to a
method for manufacturing a controlled release remediation
composition usable in a controlled release remediation system.
Further, the present invention relates to a method for remediating
a contaminated site using a controlled release remediation
composition.
BACKGROUND
[0002] The United States has more than 200,000 sites with
contaminated groundwater and subsurface soils due to leaking
underground storage tanks, industrial wastes, and accidental
spills. These contaminated sites contain over 1.7 million gallons
of chemical and foreign microbial waste; the ability to conduct
subsurface remediation is essential for controlling and reducing
potential spread of contaminants within an aquifer's watershed.
[0003] Subsurface remediation proves to be challenging because most
sites require treatment of both groundwater and subsurface soils.
Conventional methods for in-situ remediation include
pump-and-treat, thermal desorption, use of surfactants, and air
venting. Each method has benefits and limitations, but all of these
methods require a long time, many months to years, before
significant remediation is accomplished at a contaminated site.
[0004] Chemical oxidants are highly reactive gases and liquids that
can be injected into the ground to remediate both groundwater and
soils in-situ. Current oxidant delivery methods are effective in
remediating recalcitrant compounds; however, these methods are
costly, require high maintenance, and can be dangerous to workers.
Examples of chemical oxidation hazards include contact with strong
oxidizing solutions and acids, explosions, and worker injuries due
to the use of more risky techniques such as direct-push injections
for liquid delivery.
[0005] Thus there remains a need for a new and improved remediation
system and a controlled release remediation composition or
compositions that address the problems of conventional methods for
in-situ remediation.
SUMMARY
[0006] The present invention meets these and other needs by
providing a controlled release remediation composition or
compositions, a method making such composition(s), a method of
using such composition(s), and a remediation system including such
composition(s). According to various aspects of embodiments of the
present invention, a controlled release remediation composition or
compositions include at least one chemical oxidant agent,
optionally, at least two chemical oxidant agents; at least one
encapsulant polymer; and, optionally, at least one matrix polymer.
To that end according to various aspects of embodiments, a
controlled release remediation composition or compositions are
capable of substantially constantly releasing an amount of the at
least one chemical oxidant agent, optionally, amounts of the at
least two chemical oxidant agents, for example, into an aqueous
system such as may be found at a contaminated site, over at least
about a one month period up to over about a three month period.
[0007] Numerous other features and advantages of aspects of
embodiments and embodiments of the invention will appear from the
following description. In the description, reference is made to
exemplary aspects of embodiments and embodiments of the invention.
Such aspects of embodiments and embodiments do not represent the
full scope of the invention. Reference should therefore be made to
the claims herein for interpreting the full scope of the invention.
In the interest of brevity and conciseness, any ranges of values
set forth in this specification contemplate all values within the
range and are to be construed as support for claims reciting any
sub-ranges having endpoints which are real number values within the
specified range in question. By way of a hypothetical illustrative
example, a disclosure in this specification of a range of from 1 to
5 shall be considered to support claims to any of the following
ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.
[0008] In one example of an aspect of an embodiment, a controlled
release remediation composition comprises at least one pellet. As
will be appreciate by those in the art, such pellet might comprise
one or more variety of shapes and/or sizes, for example, to control
a rate of release and/or a concentration of oxidant that is
released. Some examples of one or more variety of shapes of pellets
include spheres, cylinders, "wagon wheels", gear-shapes, saddles,
disks, bricks, coils, columns, hollow-elbows, chips, fibers, or
shapes of any two or more of the preceding. Also, some examples of
one or more variety of sizes of pellets might include one of more
dimensions ranging from about a micron (.mu.m) to multiple tens of
millimeters (mm). In aspects of an embodiment, sizes can comprise
in one aspect a largest dimension of about 1 millimeter (mm, about
-18 mesh); in another aspect, between about 500 microns (.mu.m) and
about 1.0 .mu.m (about -35, +1000 mesh), and, in yet another
aspect, between about 300 microns (.mu.m) and about 1.0 .mu.m
(about -50, +635 mesh).
[0009] Examples of an at least one chemical oxidant agent includes
at least one of a photo-oxidants agent, an electron transfer
reaction agent, a free radical agent, or combinations of any two or
more of the preceding. Other examples of an at least one chemical
oxidant agent include at least one of a persulfate agent, a
permanganate agent, or combinations of any two or more of the
preceding. Such examples can include at least one of a titanium
oxide agent, a molybdenum sulfide agent, zinc sulfide agent, a
sodium permanganate agent, a potassium permanganate agent, a sodium
persulfate agent, an ammonium persulfate agent, a potassium
persulfate agent, or a combination of any two or more of the
preceding. Again, it will be appreciated that more that at least
one chemical oxidant agent can be used, for example, at least two
or even plurality. It will be appreciated that an at least one
chemical oxidant agent can come in a variety of shapes and/or
sizes. Such shapes can be a particle size comprising not greater
than about 125 .mu.m (-120 mesh), optionally between about 75
microns (.mu.m) and about 1.0 .mu.m (About -200, +1000 mesh), and
optionally between about 50 microns (.mu.m) and about 1.0 .mu.m
(about -270, +1000 mesh).
[0010] When a controlled release remediation composition includes a
matrix polymer in combination with an encapsulant polymer, the
matrix polymer can be selected to have a degradation rate less than
the release rate of the at least one chemical oxidant agent and
greater than the encapsulant degradation rate the at least one
encapsulant polymer. Also, a controlled release remediation
composition can further include at least one additional encapsulant
polymer that encapsulates at least a portion of the matrix polymer
embedding at least a portion of the encapsulated chemical oxidant
agent.
[0011] When a controlled release remediation composition includes
at least one matrix polymer in combination with at least one
encapsulant polymer, the at least one chemical oxidant agent can be
between about 1 wt % to about 60 wt % of the controlled release
remediation composition; the at least one encapsulant polymer can
be between about 1 wt % to about 99 wt % of the controlled release
remediation composition; and the at least one matrix polymer can be
the balance of the controlled release remediation composition.
[0012] Some examples of environmentally degradable polymer and/or
the biodegradable polymer include at least one of a polylactide, a
polyglycolide, a polylactide-co-glycolide, a polylactic acid, a
polyglycolic acid, a polylactic acid-co-glycolic acid, a
polycaprolactone, a polycarbonates, a polyesteramides, a
polyanhydrides, a polyamino acid, a polyorthoester, a polyacetyls,
a polycyanoacrylates, a polyetheresters, a polydioxanone, a
polyalkylen alkylate, a copolymer of a polyethylene glycol and a
polylactid or polylactide-co-glycolide, a biodegradable
polyurethane, a polysaccharide, a blend of any two or more of the
preceding, or a copolymer of any two or more of the preceding.
Blends of such polymers can include, for example, between 0 wt % to
about 100 wt % of a first polymer; between 0 wt % to about 60 wt %
of a second polymer; and a balance of a third polymer.
Alternatively, copolymers of such polymers can include, for
example, between 0 wt % to about 100 wt % of a first polymer;
between 0 wt % to about 60 wt % of a second polymer; and a balance
of a third polymer.
[0013] Among examples of environmentally degradable polymer and/or
the biodegradable polymer, polylactic acid, polyvinyl alcohol,
polycaprolactone, a blend of any two or more of the preceding, or a
copolymer of any two or more of the preceding have been found to
work satisfactorily. Blends of such polymers can include, for
example, between 0 wt % to about 60 wt % of a polylactic acid;
between 0 wt % to about 60 wt % of a polyvinyl alcohol; and between
0 wt % to about 100 wt % of a polycaprolactone. In an aspect of an
embodiment concerning polycaprolactone blends, an amount of
polycaprolactone is not less than about 40 wt % of the blend.
Alternatively, copolymers of such polymers can include, for
example, between 0 wt % to about 60 wt % of a polylactic acid;
between about 0 wt % to about 60 wt % of a polyvinyl alcohol; and
between 0 wt % to about 100 wt % of a polycaprolactone. In an
aspect of an embodiment concerning polycaprolactone copolymers, an
amount of polycaprolactone is not less than about 40 wt % of the
copolymers.
[0014] Some examples of chemical pollutants include at least one of
a chlorinated organic compound (e.g., polychlorinated biphenyls
(PCBs), chlorinated benzenes (CBs)), a compound containing at least
one unsaturated carbon-carbon bond, an aromatic hydrocarbon (AH:
e.g., benzene, toluene, ethylbenzene, xylene, [note that BTEX is an
acronym that stands for Benzene, Toluene, Ethylbenzene, and
Xylene], mesitylene, phenol, . . . etc.), a polycyclic aromatic
hydrocarbon (PAH: e.g., anthracene, chrysene, naphthalene,
phenanthrene, benzo[a]pyrene, pyrene, benz[a]anthracene,
benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene,
benzo[ghi]perylene, coronene, dibenz[a,h]anthracene
(C.sub.20H.sub.14), indeno[1,2,3-cd]pyrene (C.sub.22H.sub.12),
ovalene, . . . etc.), methyl tertiary-butyl ether (also known as
MTBE), a munitions constituent (e.g.,
cyclotrimethylenetrinitramine, also known as RDX, cyclonite,
hexogen, and T4; trinitrotoluene, also known as TNT;
cyclotetramethylene-tetranitramine, also known as HMX, and octogen;
. . . etc.), an organic pesticide, wastewater, a drinking water
treatment, a pathogen (e.g., bacteria, viruses, protozoa, fungi,
proteins, . . . etc.), or any combination of two or more of the
preceding.
[0015] Accordingly, one aspect of an embodiment the present
invention is to provide a controlled release remediation
composition that includes at least one chemical oxidant agent, at
least one encapsulant polymer, and at least one matrix polymer. The
at least one chemical oxidant agent is selected to be capable of
remediating at least one chemical pollutant. Also, the at least
encapsulant polymer is selected to be substantially compatible with
at least one chemical oxidant agent. At least a portion of the
encapsulant polymer encapsulates at least a portion of the chemical
oxidant agent. Also, at least a portion of the encapsulant polymer
includes at least one of an environmentally degradable polymer, a
biodegradable polymer, or an environmentally degradable polymer and
biodegradable polymer. As to the matrix polymer, at least a portion
of it embeds at least a portion of the encapsulated chemical
oxidant agent. As with the encapsulant polymer, at least a portion
of the matrix polymer includes at least one of an environmentally
degradable polymer, a biodegradable polymer, or an environmentally
degradable polymer and biodegradable polymer. In this manner, the
controlled release remediation composition is capable of
substantially constantly releasing an amount of the at least one
agent chemical oxidant agent, for example, into an aqueous system
such as may be found at a contaminated site, over at least about a
one month period up to over about a three month period.
[0016] Another aspect of an embodiment the present invention is to
provide a controlled release remediation composition comprising a
plurality of chemical oxidant agents and a polymer. At least two of
the plurality chemical oxidant agents are capable of remediating at
least two different chemical pollutants. At least a portion of the
polymer encapsulates at least a portion of the plurality of
chemical oxidant agents. Also, at least a portion of the polymer
comprises a biodegradable polymer. The controlled release
remediation composition is capable of substantially constantly
releasing an amount of the at least two of the plurality chemical
oxidant agents into an aqueous system over at least a one month
period up to over about a three month period.
[0017] Yet another aspect of an embodiment the present invention is
to provide a method of making controlled release remediation
composition. Steps of the method can include one or more selecting
and combining steps. For example, at least one chemical oxidant
agent capable of remediating at least one chemical pollutant is
selected. As another example, at least one encapsulant polymer that
is substantially compatible with the at least one chemical oxidant
agent is selected. Such at least one encapsulant polymer includes
at least one of an environmentally degradable polymer, a
biodegradable polymer, or an environmentally degradable polymer and
biodegradable polymer. As yet another example, at least one matrix
polymer is selected. As with the at least one encapsulant polymer,
such at least one matrix polymer includes at least one of an
environmentally degradable polymer, a biodegradable polymer, or an
environmentally degradable polymer and biodegradable polymer. The
at least one encapsulant polymer and the at least one matrix
polymer may be the same, different, or include components that are
related, such as, by a starting monomer or monomers. As to one
example of combining steps, at least a portion of the chemical
oxidant agent is encapsulated using the encapsulant polymer. As to
another example of combining steps, the encapsulated chemical
oxidant agent is combined with the at least one matrix polymer so
that at least a portion of the matrix polymer embeds at least a
portion of the encapsulated chemical oxidant agent.
[0018] Still another aspect of an embodiment of the present
invention is to provide a remediation system including at least one
controlled release remediation composition that includes at least
one chemical oxidant agent, at least one encapsulant polymer, and
at least one matrix polymer. The at least one chemical oxidant
agent is selected to be capable of remediating at least one
chemical pollutant. Also, the at least encapsulant polymer is
selected to be substantially compatible with at least one chemical
oxidant agent. At least a portion of the encapsulant polymer
encapsulates at least a portion of the chemical oxidant agent.
Also, at least a portion of the encapsulant polymer includes at
least one of an environmentally degradable polymer, a biodegradable
polymer, or an environmentally degradable polymer and biodegradable
polymer. As to the matrix polymer, at least a portion of it embeds
at least a portion of the encapsulated chemical oxidant agent. As
with the encapsulant polymer, at least a portion of the matrix
polymer includes at least one of an environmentally degradable
polymer, a biodegradable polymer, or an environmentally degradable
polymer and biodegradable polymer. In this manner, the remediation
product is capable of substantially constantly releasing a
sufficient amount of the at least one agent chemical oxidant agent
into a contaminated site over at least about a one month period up
to over about a three month period so as to remediate at least a
portion of the at least one chemical pollutant.
[0019] Still yet another aspect of an embodiment the present
invention is to provide a method of using a controlled release
remediation composition. Steps of the method can include one or
more determining, selecting, combining, and providing steps. For
example, at least one chemical pollutant to be remediated at a
contaminated site is identified. Then, at least one chemical
oxidant agent capable of remediating the at least one chemical
pollutant is selected. Another selecting example includes selecting
at least one encapsulant polymer that is substantially compatible
with the at least one chemical oxidant agent is selected. Such at
least one encapsulant polymer includes at least one of an
environmentally degradable polymer, a biodegradable polymer, or an
environmentally degradable polymer and biodegradable polymer. As
yet another example, at least one matrix polymer is selected. As
with the at least one encapsulant polymer, such at least one matrix
polymer includes at least one of an environmentally degradable
polymer, a biodegradable polymer, or an environmentally degradable
polymer and biodegradable polymer. The at least one encapsulant
polymer and the at least one matrix polymer may be the same,
different, or include components that are related, such as, by a
starting monomer or monomers. As to one example of combining steps,
at least a portion of the chemical oxidant agent is encapsulated
using the encapsulant polymer. As to another example of combining
steps, the encapsulated chemical oxidant agent is combined with the
at least one matrix polymer so that at least a portion of the
matrix polymer embeds at least a portion of the encapsulated
chemical oxidant agent to form a controlled release remediation
composition. Further steps involve shaping, sizing, and/or
providing. For example, the controlled release remediation
composition is shaped, sized, or shaped and sized so as to be
capable of substantially constantly releasing an amount of the at
least one chemical oxidant agent, for example, into an aqueous
system of a contamination site, over at least about a one month
period up to over about a three month period. As to an example of
providing, a sufficient amount of the shaped, sized, or shaped and
sized controlled release remediation composition is provided to the
contaminated site in manner that remediates at least a portion of
the at least one chemical pollutant at the contaminated site.
[0020] These and other aspects, advantages, and salient features of
the present invention will become apparent from the following
detailed description, the accompanying drawings, and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 is a schematic illustrating a controlled release
remediation composition constructed according to an aspect of an
embodiment of the present invention;
[0022] FIG. 2 is a schematic illustrating a controlled release
remediation composition constructed according to another aspect of
an embodiment of the present invention;
[0023] FIG. 3 is a schematic illustrating a controlled release
remediation composition constructed according to yet another aspect
of an embodiment of the present invention;
[0024] FIGS. 4a and 4b are photos of the KMnO.sub.4 in a PLA
polymer photographed after it was made (FIG. 4a) and approximately
seven months later (FIG. 4b);
[0025] FIGS. 5a and 5b are photos of the KMnO.sub.4 in a
polycaprolactone (PCL) polymer photographed after it was made (FIG.
5a) and approximately seven months later (FIG. 5b);
[0026] FIG. 6 is a plot comparing degradation of a PAB-50 and a
PAB-60 polymer blend for pellet design;
[0027] FIG. 7 is a photograph showing visible attachment of plant
material growing on pellets after about six months;
[0028] FIG. 8 is a plot comparing degradation in river water and
culture water of pellets made using a PAB-100 and a PAB-60 polymer
blend for;
[0029] FIGS. 9a, 9b, and 9c are time series photographs of a
chemical oxidant agent diffusing from a controlled release
remediation composition;
[0030] FIG. 10 is a plot showing the time release of a chemical
oxidant agent;
[0031] FIG. 11 is a plot showing the time release of a chemical
oxidant agent;
[0032] FIG. 12 is a plot comparing the short-term time release of a
chemical oxidant agent using different polymers;
[0033] FIG. 13 is a plot comparing the short-term time release of a
chemical oxidant agent using different polymers;
[0034] FIG. 14 is a plot comparing the short-term time release of a
chemical oxidant agent using different polymers;
[0035] FIG. 15 is a plot showing the release rate of a chemical
oxidant agent for a controlled release remediation composition;
[0036] FIG. 16 is a plot showing the release rate of a chemical
oxidant agent for a controlled release remediation composition;
[0037] FIG. 17 is a plot showing the release rate of a chemical
oxidant agent for a controlled release remediation composition;
and
[0038] FIG. 18 is a plot showing the release rate of a chemical
oxidant agent for a controlled release remediation composition.
DETAILED DESCRIPTION
[0039] In the following description, like-referenced characters
designate like or corresponding parts throughout the several views
shown in the figures. It is also understood that terms such as
"top," "bottom," "outward," "inward," and the like are words of
convenience and are not to be construed as limiting terms.
[0040] Referring to the drawings in general and to FIGS. 1, 2, and
3 in particular, it will be understood that the illustrations are
for the purpose of describing one or more aspects of and/or one or
more embodiments of the invention and are not intended to limit the
invention thereto. In FIGS. 1, 2, and 3, a controlled release
remediation composition is generally designated 12. Such
composition 12 includes at least one chemical oxidant agent 14 and
at least one matrix polymer 20. Such composition 12 can include at
least one encapsulant polymer 16. The at least one chemical oxidant
agent 14 is selected to be capable of remediating at least one
chemical pollutant 22 (not depicted in FIGS. 1, 2, and 3). A matrix
polymer 20 is selected to be substantially compatible with at least
one chemical oxidant agent 14 and at least a portion of it embeds
at least a portion of the chemical oxidant agent 14. At least a
portion of the matrix polymer 20 includes at least one of an
environmentally degradable polymer, a biodegradable polymer, or an
environmentally degradable polymer and biodegradable polymer. In
this manner, the controlled release remediation composition 12 can
be capable of substantially constantly releasing an amount of the
at least one agent chemical oxidant agent 14, for example, into an
aqueous system such as may be found at a contaminated site, over at
least about a one month period up to over about a three month
period. Also, the at least one encapsulant polymer 16 is selected
to be substantially compatible with at least one chemical oxidant
agent 14.
[0041] In some aspects of embodiments of the present invention as
shown in FIG. 3, at least a portion of an encapsulant polymer 16
encapsulates at least a portion of a chemical oxidant agent 14.
Such encapsulant polymer 16 can include at least one of an
environmentally degradable polymer, a biodegradable polymer, or an
environmentally degradable polymer and biodegradable polymer. Is
such case, at least a portion of a matrix polymer 20 embeds at
least a portion of the encapsulated chemical oxidant agent 14'. As
with the matrix polymer 20, at least a portion of the encapsulant
polymer 16 includes at least one of an environmentally degradable
polymer, a biodegradable polymer, or an environmentally degradable
polymer and biodegradable polymer. In this manner, the controlled
release remediation composition is capable of substantially
constantly releasing an amount of the at least one agent chemical
oxidant agent, for example, into an aqueous system such as may be
found at a contaminated site, over at least about a one month
period up to over about a three month period.
[0042] "Degradable" or "degradation" is intended to mean that the
polymer undergoes an irreversible process that leads to a
significant change in the chemical and/or physical structure of the
material that is typically characterized by a loss of physical
and/or chemical properties, such as integrity, molecular weight,
molecular structure, mechanical strength, and/or fragmentation. In
an aspect, a polymer degrades to a benign non-toxic material that
is not harmful to the environment.
[0043] A degradation of a polymer can be by a process that involves
one or more of, for example, photodegradation, chemical
degradation, physical degradation or, biodegradation.
Photodegradation includes a process of degradation that can be
initiated by exposure of the polymer to natural or artificial
light. Chemical degradation includes a process of degradation
wherein chemical bonds in the polymer are broken as a result of one
or more chemical reactions such as, for example, hydrolysis,
thermal cleavage, or oxidation. Chemical degradation is thus more
encompassing than photodegradation, since the reactions are not
limited to those initiated by exposure to light. Physical
degradation can include forces such as erosion that may help a
polymer to degrade. Biodegradation includes a process of
degradation that occurs as a result of the action of enzymes,
derived from the metabolic processes of microorganisms or other
living species, on the polymer. It is possible that a given
mechanism of degradation may be classified as more than one of the
above-described processes.
[0044] "Biodegradable" means that a polymer or polymer component is
susceptible to being assimilated by microorganisms when buried in
the ground or otherwise contacted with the organisms under
conditions conducive to their growth.
[0045] "Environmentally degradable" means that a polymer or polymer
component is capable of being degraded by surrounding environmental
elements (e.g., chemical, physical, thermal, and/or light) without
microorganisms to a form that ultimately may be biodegradable when
it mineralizes, for example, biodegrades to carbon dioxide, water
and biomass.
[0046] Conditions that enable the chemical, physical, thermal
and/or biological degradation of a polymer or polymer component may
vary. A polymer or polymer component of this invention are
especially adapted to be degradable in soil and/or subterranean
applications.
[0047] It will be appreciated that in aspects of embodiments of the
present invention, a controlled release remediation composition 12
might be used in an alone process or in conjunction with another
engineered system as a remediation system 10. For example, a
controlled release remediation composition 12 might comprise at
least one pellet 22, a plurality of which is capable of being
packed into a screened well or mix into the soil to form a
permeable barrier layer at a contamination site. Such a barrier
layer of controlled release remediation composition 12 would be
capable of releasing one or more chemical oxidant agents 14 as
groundwater flows through it to react with contaminated water and
chemical pollutants 24 present in the soil and/or subterranean
level.
[0048] As noted, a controlled release remediation composition 12
might comprise at least one pellet 22. As will be appreciate by
those in the art, such pellet might comprise one or more variety of
shapes and/or sizes, for example, to control a rate of release
and/or a concentration of oxidant that is released. Some examples
of one or more variety of shapes of pellets include spheres,
cylinders, "wagon wheels", gear-shapes, saddles, disks, bricks,
coils, columns, hollow-elbows, chips, fibers, or shapes of any two
or more of the preceding. Also, some examples of one or more
variety of sizes of pellets might include one of more dimensions
ranging from about a micron (.mu.m) to multiple tens of millimeters
(mm). In one aspect of an embodiment, sizes can comprise in one
aspect a largest dimension of about 1 millimeter (mm, about -18
mesh); in another aspect, between about 500 microns (.mu.m) and
about 1.0 .mu.m (about -35, +1000 mesh), and, in yet another
aspect, between about 300 microns (.mu.m) and about 1.0 .mu.m
(about -50, +635 mesh).
[0049] Examples of an at least one chemical oxidant agent 14
includes at least one of a photo-oxidants agent, an electron
transfer reaction agent, a free radical agent, or combinations of
any two or more of the preceding. Other examples of an at least one
chemical oxidant agent include at least one of a persulfate agent,
a permanganate agent, or combinations of any two or more of the
preceding. Such examples can include at least one of a titanium
oxide agent, a molybdenum sulfide agent, a zinc sulfide agent, a
sodium permanganate agent, a potassium permanganate agent, sodium
persulfate agent, ammonium persulfate agent, potassium persulfate
agent, or a combination of any two or more of the preceding. Again,
it will be appreciated that more that at least one chemical oxidant
agent 14 can be used, for example, at least two (e.g., a first
chemical oxidant agent 14 and a second chemical oxidant agent 14')
or even plurality (e.g., chemical oxidant agent 14, a second
chemical oxidant agent 14', . . . a n.sup.th chemical agent
14.sup.n). It will be appreciate that an at least one chemical
oxidant agent can come in a variety of shapes and/or sizes. Such
shapes can be a particle size comprising not greater than about 125
.mu.m (-120 mesh), optionally between about 75 microns (.mu.m) and
about 1.0 .mu.m (About -200, +1000 mesh), and optionally between
about 50 microns (.mu.m) and about 1.0 .mu.m (about -270, +1000
mesh).
[0050] When a controlled release remediation composition 12
includes a matrix polymer 20 in combination with an encapsulant
polymer 16, the matrix polymer 20 can be selected to have a
degradation rate less than the release rate of the at least one
chemical oxidant agent 14 and greater than the degradation rate of
the at least one encapsulant polymer 16. Also, a controlled release
remediation composition 12 can further include at least one
additional encapsulant polymer 18 that encapsulates at least a
portion of the matrix polymer 20 embedding at least a portion of
the encapsulated chemical oxidant agent 14.
[0051] When a controlled release remediation composition 12
includes at least one matrix polymer 20 in combination with at
least one encapsulant polymer 16, the at least one chemical oxidant
agent 14 can be between about 1 wt % to about 60 wt % of the
controlled release remediation composition 12; the at least one
encapsulant polymer 16 can be between about 1 wt % to about 99 wt %
of the controlled release remediation composition 12; and the at
least one matrix polymer 20 can be the balance of the controlled
release remediation composition 12.
[0052] Some examples of environmentally degradable polymer and/or
the biodegradable polymer include at least one of a polylactide, a
polyglycolide, a polylactide-co-glycolide, a polylactic acid,
polyglycolic acid, polylactic acid-co-glycolic acid, a
polycaprolactone, a polycarbonates, a polyesteramides, a
polyanhydrides, a polyamino acid, a polyorthoester, a polyacetyls,
a polycyanoacrylates, polyetheresters, a polydioxanone, a
polyalkylen alkylate, a copolymer of a polyethylene glycol and a
polylactid or polylactide-co-glycolide, a biodegradable
polyurethane, a polysaccharide, a blend of any two or more of the
preceding, or a copolymer of any two or more of the preceding.
Blends of such polymers can include, for example, between 0 wt % to
about 100 wt % of a first polymer; between 0 wt % to about 60 wt %
of a second polymer; and a balance of a third polymer.
Alternatively copolymers of such polymers can include, for example,
between 0 wt % to about 100 wt % of a first polymer; between 0 wt %
to about 60 wt % of a second polymer; and a balance of a third
polymer.
[0053] Among examples of environmentally degradable polymer and/or
the biodegradable polymer, polylactic acid, polyvinyl alcohol,
polycaprolactone, a blend of any two or more of the preceding, or a
copolymer of any two or more of the preceding have been found to
work satisfactorily. Blends of such polymers can include, for
example, between 0 wt % to about 60 wt % of a polylactic acid;
between 0 wt % to about 60 wt % of a polyvinyl alcohol; and between
0 to about 100 wt % of a polycaprolactone. Alternatively copolymers
of such polymers can include, for example, between 0 wt % to about
100 wt % of a polylactic acid; between 0 wt % to about 60 wt % of a
polyvinyl alcohol; and between 0 wt % to about 100 wt % of a
polycaprolactone.
[0054] Some examples of chemical pollutants 24 include at least one
of a chlorinated organic compound (e.g., polychlorinated biphenyls
(PCBs), chlorinated benzenes (CBs)), a compound containing at least
one unsaturated carbon-carbon bond, an aromatic hydrocarbon (AH:
e.g., benzene, toluene, ethylbenzene, xylene, [note that BTEX is an
acronym that stands for Benzene, Toluene, Ethylbenzene, and
Xylene], mesitylene, phenol, . . . etc.), a polycyclic aromatic
hydrocarbon (PAH: e.g., anthracene, chrysene, naphthalene,
phenanthrene, benzo[a]pyrene, pyrene, benz[a]anthracene,
benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene,
benzo[ghi]perylene, coronene, dibenz[a,h]anthracene
(C.sub.20H.sub.14), indeno[1,2,3-cd]pyrene (C.sub.22H.sub.12),
ovalene, . . . etc.), methyl tertiary-butyl ether (also known as
MTBE), a munitions constituent (e.g.,
cyclotrimethylenetrinitramine, also known as RDX, cyclonite,
hexogen, and T4; trinitrotoluene, also known as TNT;
cyclotetramethylene-tetranitramine, also known as HMX, and octogen;
. . . etc.), an organic pesticide, wastewater, a drinking water
treatment, a pathogen (e.g., bacteria, viruses, protozoa, fungi,
proteins, . . . etc.), or any two or more of the preceding.
[0055] In an operation according an aspect of an embodiment
relating to delayed dissolution as shown to FIG. 1, polymer matrix
20 environmentally degrades (e.g., dissolves in the presence of
water or degrades slowly in the presence of water) and/or
biologically degrades (e.g., due to microbial action). Some
embedded and/or encapsulated chemical oxidant agent 14 is retained
until further degradation of the polymer. Released chemical oxidant
agent 14 is available to dissolve and react with one or more
chemical pollutants 24.
[0056] In an operation according an aspect of an embodiment
relating to diffusion controlled as shown to FIG. 2, polymer matrix
20 environmentally degrades (e.g., moderately water soluble with
small pore openings created by water flow) and/or biologically
degrades (e.g., due to microbial action). Chemical oxidant agent 14
diffuses with water flow into the environment to react one or more
chemical pollutants 24. FIG. 2 explains diffusion controlled
release of the encapsulated oxidant. For example, the polymer
matrix 20 may be moderately soluble and/or have small pore openings
created due to the semi-permeable property for the polymer, water
flow or microbial degradation. This enables a chemical oxidant
agent 14 to diffuse across a shell boundary.
[0057] In an operation according an aspect of an embodiment
relating to delayed dissolution in combination with diffusion
controlled as shown to FIG. 3, additional encapsulant polymer 18
environmentally degrades (e.g., moderately water soluble with small
pore openings created by water flow) and/or biologically degrades
(e.g., due to microbial action). Polymer matrix 20 permits
diffusion of some but not all of chemical oxidant agent 14'.
Delayed dissolution leads to the delayed release of remaining
chemical oxidant agent 14 that eventually diffuses with water flow
into the environment to react with one or more chemical pollutants
24.
EXAMPLES
[0058] Certified ACS KMnO.sub.4 (Fisher Chemical, Fair Lawn, N.J.)
was used as the oxidant encapsulated in an environmentally
degradable polymer, a biodegradable polymer, an environmentally
degradable polymer and biodegradable polymer, a copolymer thereof,
or a blend thereof Poly-lactic acid (NatureWorks LLC, Minnetonka,
Minn.), polyvinyl alcohol (Aldrich Chemical, Milwaukee, Wis.), and
polycaprolactone (Dow Chemical, Midland Mich.) were evaluated.
[0059] To produce controlled release remediation compositions, pure
polymers and polymer blends were combined to produce about 0.3 to
about 0.5 cm solid pellets. Molten polymer was created by heating a
polymer above its melting point in an aluminum dish or Pyrex.RTM.
beaker using a hot plate stirrer. KMnO.sub.4 was stirred into the
molten polymer to suspend KMnO.sub.4. Pellets were then formed by
placing the viscous molten suspension in a mold to solidify and
form the pellets.
[0060] Those skilled in the art will appreciate that other methods
might be used to make a controlled release remediation composition
according to aspects of embodiments and/or embodiments of the
present invention. For example, an extrusion process might be used
to incorporate one or more chemical oxidant agents with matrix
polymer with the elongate extrudant being chopped to form pellets.
Other methods might include fiber spinning, injection molding,
mixing and compounding, pultrusion, and reaction injection
molding.
[0061] Criteria for an environmentally degradable polymer or a
biodegradable polymer selection includes a compatibility with a
selected chemical oxidant agent, in the examples KMnO.sub.4, an
ability to form solid pellet structures. In an aspect of an
embodiment of the invention, a largest dimension of a pellet might
comprises about 1 millimeter (mm, about -18 mesh), optionally
between about 500 microns (.mu.m) and about 1.0 .mu.m (about -35,
+1000 mesh), and optionally between about 300 microns (.mu.m) and
about 1.0 .mu.m (about -50, +635 mesh), and an ability of such
polymer to degrade or dissolve to release the chemical oxidant
agent.
[0062] Applicant contemplates controlled release remediation
compositions that exhibited delayed dissolution delivery, diffusion
controlled delivery, or combined delayed/diffusion delivery of a
chemical oxidant agent, in the examples KMnO.sub.4. In a controlled
release remediation composition exhibiting delayed diffusion, a
polymer either dissolves in water or degrades due to microbial
action to release chemical oxidant agent, in the examples
KMnO.sub.4. In a controlled release remediation composition
exhibiting diffusion control, a chemical oxidant agent, in the
examples KMnO.sub.4, is able to diffuse through the matrix polymer
into water. FIGS. 1, 2, and 3 depict designs to enable the
controlled release of oxidants from a biodegradable polymer.
[0063] Evaluated polymers included polylactic acid (PLA), polyvinyl
alcohol (PVOH), and polycaprolactone (PCL). Polylactic acid (PLA),
an aliphatic polyester, is a hydrophobic, biodegradable polymer
that can be degraded by aerobic or anaerobic. Polylactic acid has a
thermal melting point at about 193.degree. C., therefore the
melting point for the polymer is less than the melting point of
potassium permanganate (270.degree. C.). Polyvinyl alcohol (PVOH)
is a hydrophilic polymer selected for use as a polymer blend and
has a melting temperature of about 200.degree. C. Applicant
believes that PVOH could be used in blends to provide a method to
increase the diffusion of KMnO.sub.4 into water. Polycaprolactone
(PCL) is a biodegradable polymer having a melting temperature of
about 60.degree. C. and is degradable under aerobic and anaerobic
conditions.
[0064] Polylactic acid, polyvinyl alcohol, and polycaprolactone
were tested for reactivity with KMnO.sub.4. One concern for
encapsulant polymer and/or matrix polymer is that a chemical
oxidant agent is adversely affected by an interaction or reaction.
For example, if the KMnO.sub.4 is reactive with polymer, visible
evidence would be a brown discoloration caused by MnO.sub.2 from
KMnO.sub.4 degradation or visible degradation of the polymer. For
this test, KMnO.sub.4 was encapsulated using PLA, PVOH blends, and
PCL matrices to form pellets and mounted on a glass slide. Photos
at 40.times. and 100.times. were taken of the pellets using a
digital microscope to observe any reactions or discoloration of the
matrix. Little to no reactivity was seen in PLA, PVOH blends, and
PCL matrices. FIGS. 4(a) and 4(b) show that KMnO.sub.4 appears to
be stable and non-reactive when in contact with PLA. FIG. 4a is a
photo of the KMnO.sub.4 in the PLA polymer photographed after it
was made and FIG. 4b shows the same sample photographed
approximately seven month later. FIGS. 4a and 4b show that
KMnO.sub.4 appears to be stable and non-reactive when in contact
with PLA. FIG. 5a is a photo of the KMnO.sub.4 in the PCL polymer
photographed after it was made and FIG. 5b shows the same sample
photographed approximately seven months later. FIGS. 5a and 5b show
that KMnO.sub.4 appears to be stable and non-reactive when in
contact with PCL.
[0065] Six controlled release remediation compositions met the
criteria (e.g., (1) polymer compatibility with the chemical oxidant
agent, (2) the ability for diffusion of the chemical oxidant agent
through the polymer, and (3) the ability to form pellet structures
using the polymer that is feasible for use as fill material for a
permeable reactive barrier or in a reactor system). Identification
numbers were assigned to the polymer and polymer blends, namely,
PAB-50, PAB-60, PAB-70, PAB-80, PAB-90, and PAB-100 were PAB stand
for a blend of polycarprolactone (PCL) and polyvinyl alcohol (PVOH)
and -X stand for the amount in weight percent of PCL blended with
PVOH. These samples were mixtures of hydrophilic and hydrophobic
polymers blended to create pellets that would dissolve and/or
degrade in the presence of water to release the chemical oxidant
agent.
[0066] Water evaluated included water collected from Reedy Fork
Ranch Creek (Greensboro, N.C.), culture water containing 12 aerobic
microorganisms from the PolyTox cultures (Fisher Scientific
Company, Fair Lawn, N.J.), and deionized water over a period of six
months. These tests were conducted to determine dissolution and
degradation of the pellet blends in aqueous media. The FIG. 6
summarizes data from an experiment over a 70 day period using the
hydrophilic polymer (in this case PVOH) blended in with the
polycarprolactone in samples PAB-50 and PAB-60.
[0067] The PAB-50 controlled release remediation composition had an
increased dissolution rate in aqueous media compared to PAB-60.
This result provided data for designing controlled release
remediation compositions to release the chemical oxidant agent at
slower or faster rates. That is blends with higher concentrations
of the hydrophilic polymer (i.e., PAB-50) dissolve to yield a rapid
release of oxidant. Slower, controlled release rates are therefore
feasible in polymer blends with less hydrophilic polymer blended in
the matrix (i.e., PAB-60).
[0068] Dissolution and Degradation experiments of Polymer blends
over a 90 day period were designed to investigate dissolution and
degradation of the polymer in natural water such as river water and
aqueous, aerobic mixed culture. In the lab, the polymers were
evaluated in a batch system with 100 ml of river water or culture
water. The table below represents the experiment carried out in the
lab over a period of 118 days to show how two different polymer
blends (PAB-60 and PAB-100) blends dissolved or degraded in aqueous
media (Table 1).
TABLE-US-00001 TABLE 1 Dissolution and degradation - Days of
Degradation SAMPLES 0 2 7 13 22 41 55 83 90 118 Percent Reduction
in Mass DI Water (PAB-100)* River Water (PAB-100) 0 0.4 1.3 1.6 1.8
2.1 2.2 2.3 2.5 5.7 Mixed Culture (PAB-100) 0 0 0 3.2 3.5 5.2 6.3
8.0 8.5 11.7 DI water (non-sterile) (PAB-60) 0 0.3 6.5 7.5 18.0
30.5 33.1 33.6 33.7 35.0 River Water (PAB-60) 0 0.2 5.6 6.5 15.2
31.7 32.8 33.4 34.7 33.5 Mixed Culture (PAB-60) 0 1 6.0 8.1 14.2
31.2 33.8 35.1 35.3 37.5 *data not available at time of filing
[0069] Biological growth was seen on the PAB-100 pellets after
about six-months in the batch water (See e.g., FIG. 7). No
biological growth was evident on the PAB-60 samples. The pH for the
batches, both PAB-60 and PAB-100, ranged from about 6.7-7.5
suggesting the pH level was not the cause for the lack of
biological growth in the bottles. Perhaps the lack of growth was
due to the addition of the second polymer in the pellet. FIG. 8
includes the results of a study of polymer and polymer blends
PAB-100 and PAB-60 normalized to show degradation over 2-months in
river water and mixed microbial culture water.
[0070] The profile in FIGS. 9a, 9b and 9c shows a controlled
release remediation composition and a chemical oxidant agent
diffusing therefrom. The chemical oxidant agent is embedded in a
polymer matrix; this also shows the slow release of the oxidant
from pellets of controlled release remediation composition over
time, the purple color residue coming out of the matrix is the
chemical oxidant agent, potassium permanganate.
[0071] Biphasic KMnO.sub.4 release was observed in our KMnO.sub.4
release studies. A rapid release of KMnO.sub.4 occurred during the
initial about 1-3 days followed by a controlled and slower release
of KMnO4 for an extended period of time. (See e.g., FIGS. 10 &
11).
[0072] FIG. 10 relates to a replacement media study of 0.5 g of
pellets containing 0.01 g of oxidant. Also, FIG. 11 relates to a
replacement media study of 0.5 g of pellets containing 0.1 g of
oxidant. The oxidant concentration was measured every 2-4 days.
After each measurement, the pellets and bottles were rinsed to
remove residual oxidant and fresh water added to the reaction
bottles. The process of measuring the oxidant concentration was
then repeated 2-3 days later.
[0073] FIG. 12 relates to a one-hour release study of 0.5 g of
pellets containing 0.01 g oxidant in the polymer and polymer blends
PAB-50, PAB-60, PAB-70, PAB-80, PAB-90, and PAB-100. FIG. 13
relates to a one-hour release study of 0.5 g of pellets containing
0.1 g oxidant in the polymer and polymer blends PAB-50, PAB-60,
PAB-70, PAB-80, PAB-90, and PAB-100. FIG. 14 relates to a four-hour
release study of 0.5 g of pellets containing 0.1 g oxidant in the
polymer and polymer blends PAB-50, PAB-60, PAB-70, PAB-80, PAB-90,
and PAB-100.
[0074] FIG. 15 is a linear-fit for release data from 0.5 g of
pellets containing 0.01 g oxidant to determine the release rate.
FIG. 16 is a bar chart presenting continuous release concentration
measurements of oxidant release from 0.5 g of pellets containing
0.01 g of oxidant.
[0075] FIG. 17 is a linear-fit for release data from 0.5 g of
pellets containing 0.1 g oxidant to determine the release rate.
FIG. 18 is a bar chart presenting continuous release concentration
measurements of oxidant release from 0.5 g of pellets containing
0.1 g of oxidant
[0076] Controlled release remediation compositions based on the
polymer blends were made. Chemical oxidant agent release was
delayed by increasing the amount of PCL in the polymer blends.
PAB-50, PAB-60 and PAB-70 contained 50%, 60% and 70% PCL in the
polymer blend respectively. These polymers released KMnO.sub.4
faster than PAB-80 and PAB-100. It was also observed that
homogenous mixing of the polymers for the blends was beneficial.
PVOH is hydrophilic and will readily dissolve in water leaving
pores in the hydrophobic PCL matrix. When PVOH is not homogeneously
mixed in the interior of the matrix and PVOH crystals are located
on the surface of the pellet, KMnO.sub.4 will be released in to the
water at a faster rate. This was observed in PAB-90 which
demonstrated a significantly higher release rate for the
oxidants.
[0077] Controlled release remediation composition PAB-50 which is a
50/50 and controlled release remediation composition PAB-60 which
is as a 60/40 mix of two polymers released KMnO.sub.4 at a faster
rate than PAB-80 and PAB-100. Controlled release remediation
composition PAB-90 exhibited a higher than expected release rate
for KMnO.sub.4 compared to the other samples. Applicant believes
that the polymer blend was not homogenously distributed throughout
the pellet. Either more dissolution polymer was present at the
surface of the pellet or surface imbedded KMnO4 was present on the
surface of the pellet and caused a rapid release of the
oxidant.
[0078] While typical embodiments have been set forth for the
purpose of illustration, the foregoing description should not be
deemed to be a limitation on the scope of the invention.
Accordingly, various modifications, adaptations, and alternatives
may occur to one skilled in the art without departing from the
spirit and scope of the present invention. It should be understood
that all such modifications and improvements have been deleted
herein for the sake of conciseness and readability but are properly
within the scope of the following claims.
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