U.S. patent application number 10/715337 was filed with the patent office on 2004-07-15 for hydratable form of keratin for use as a soil amendment.
This patent application is currently assigned to Southwest Research Institute. Invention is credited to Blanchard, Cheryl R., Siller-Jackson, Arlene J., Smith, Robert Allen, Timmons, Scott F., Van Dyke, Mark E..
Application Number | 20040134248 10/715337 |
Document ID | / |
Family ID | 24056956 |
Filed Date | 2004-07-15 |
United States Patent
Application |
20040134248 |
Kind Code |
A1 |
Smith, Robert Allen ; et
al. |
July 15, 2004 |
Hydratable form of keratin for use as a soil amendment
Abstract
A hydratable oxidized keratin composition comprising one or more
metal ion species capable of absorbing water to form a hydrogel.
The keratin material is useful as a soil amendment providing
organic and inorganic nutrients. The keratin material is also
useful as a nutrient source in the bioremediation of toxic
contaminants soils and liquids.
Inventors: |
Smith, Robert Allen;
(Jackson, IN) ; Timmons, Scott F.; (San Antonio,
TX) ; Van Dyke, Mark E.; (Fair Oaks Ranch, TX)
; Blanchard, Cheryl R.; (Warsaw, IN) ;
Siller-Jackson, Arlene J.; (Helotes, TX) |
Correspondence
Address: |
VINSON & ELKINS, L.L.P.
1001 FANNIN STREET
2300 FIRST CITY TOWER
HOUSTON
TX
77002-6760
US
|
Assignee: |
Southwest Research
Institute
Keraplast Technologies, Ltd.
|
Family ID: |
24056956 |
Appl. No.: |
10/715337 |
Filed: |
November 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10715337 |
Nov 17, 2003 |
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09516755 |
Mar 1, 2000 |
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6649740 |
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Current U.S.
Class: |
71/15 |
Current CPC
Class: |
Y02P 20/145 20151101;
C05F 11/08 20130101; Y02W 30/47 20150501; Y10S 106/90 20130101;
C09K 17/32 20130101; Y02A 40/201 20180101; Y02A 40/203 20180101;
Y02E 50/343 20130101; Y02E 50/30 20130101; Y02W 30/40 20150501;
Y10S 530/842 20130101; C05F 1/007 20130101; C05F 1/005 20130101;
Y02A 40/20 20180101 |
Class at
Publication: |
071/015 |
International
Class: |
C05F 001/00 |
Claims
What is claimed is:
1. A soil amendment composition comprising an insoluble hydratable
keratin or an insoluble keratin hydrogel, wherein said hydratable
keratin or keratin hydrogel is associated with one or more cationic
species.
2. The soil amendment of claim 1, wherein said hydratable keratin
or keratin hydrogel comprises sulfonate groups.
3. The soil amendment composition of claim 1, wherein said keratin
is derived from a source selected from the group consisting of
hair, feathers, leather, nail, skin, hooves, fur, beaks, claws and
scales.
4. The soil amendment composition of claim 1, wherein said one or
more cationic species comprise one or more metal ion species
5. The soil amendment composition of claim 4, wherein said one or
more metal ion species are selected from the group consisting of
potassium, sodium, copper, zinc, manganese, magnesium and
calcium.
6. The soil amendment of composition of claim 1, further comprising
a preservative.
7. The soil amendment of composition of claim 6, wherein said
preservative is a tetraalkylammonium hydroxide.
8. A soil amendment composition comprising an insoluble keratin
hydrogel or an insoluble hydratable keratin, wherein said keratin
hydrogel or hydratable keratin is derived from hair, includes
sulfonate groups and is associated with a plurality of metal ion
species.
9. The soil amendment composition of claim 8, wherein said
plurality of metal ion species are selected from the group
consisting of potassium, sodium, copper, zinc, manganese, magnesium
and calcium.
10. The soil amendment of composition of claim 8, further
comprising a preservative.
11. The soil amendment of composition of claim 10, wherein said
preservative is a tetraalkylammonium hydroxide.
12. A soil amendment composition comprising an insoluble oxidized
hydratable keratin made by the process comprising: (a) oxidizing
disulfide bonds in a keratin material with an oxidizing agent to
obtain an oxidized keratin solid having sulfonic acid residues; (b)
contacting said oxidized keratin solid with a neutral or slightly
alkaline water-miscible solvent containing one or metal ion
species, such that said one or more metal ion species are
associated with said oxidized keratin solid; and (c) substantially
removing said water-miscible solvent to obtain an oxidized
hydratable keratin.
13. The soil amendment composition of claim 12, further comprising
hydrating said oxidized hydratable keratin to obtain an oxidized
keratin hydrogel.
14. The soil amendment composition of claim 12, wherein said
neutral or slightly alkaline water-miscible solvent comprises up to
about 20 volume percent water.
15. The soil amendment composition of claim 12, wherein said
keratin material is derived from a source selected from the group
consisting of hair, feathers, leather, nail, skin, hooves, fur,
beaks, claws and scales.
16. The soil amendment composition of claim 12, wherein said one or
more metal ion species are selected from the group consisting of
potassium, sodium, copper, zinc, manganese, magnesium and
scales.
17. The soil amendment composition of claim 12, wherein said
oxidizing agent is selected from the group consisting of hydrogen
peroxide, alkali peroxides, peracids, perborates, percarbonates,
persulfates, hypochlorite and chlorine dioxide.
18. The soil amendment composition of claim 12, wherein said
water-miscible solvent is a lower alkyl alcohol selected from the
group consisting of methanol, ethanol, isopropanol, n-propanol,
t-butanol and combinations thereof.
19. A process for making an insoluble hydratable keratin-derived
soil amendment material comprising the steps: (a) oxidizing a
keratin material in a first solution with an oxidizing agent such
that a portion of the disulfide bonds of said keratin material are
oxidized to form sulfonate groups, to form an oxidized keratin
solid fraction; (b) separating said oxidized keratin solid fraction
from said first solution; (c) contacting said oxidized keratin
fraction with a second solution comprising one or more metal ion
species, dissolved in a neutral or slightly alkaline water-miscible
solvent; (d) maintaining said second solution containing said
oxidized keratin fraction and said one or more metal ion species
for a time and temperature effective to cause an association
between said oxidized keratin and said one or more metal ion
species; and (e) substantially removing the solvent from said
oxidized keratin fraction associated with said one or more cationic
species to obtain a hydratable keratin material.
20. The process of claim 19, further comprising hydration of said
hydratable keratin material to form a keratin hydrogel.
21. The process of claim 19, wherein said neutral or slightly
alkaline water-miscible solvent comprises up to about 20 volume
percent water
22. The process of claim 19, wherein said keratin material is
derived from a source selected from the group consisting of hair,
feathers, leather, horn, nail, skin, hooves, fur, beaks, claws and
scales.
23. The process of claim 19, wherein said oxidizing agent is
selected from the group consisting of hydrogen peroxide, alkali
peroxides, peracids, perborates, percarbonates, and persulfates,
hypochlorite and chlorine dioxide.
24. The process of claim 19, wherein said water soluble solvent is
a lower alkyl alcohols selected from the group consisting of
methanol, ethanol, n-propanol, isopropanol, t-butanol and
combinations thereof.
25. The process of claim 19, wherein said one or more metal ion
species are selected from the group consisting of potassium,
sodium, copper, zinc, manganese, magnesium and calcium.
26. A method for increasing the water retention properties of soil,
comprising addition to soil of an insoluble hydratable keratin
material.
27. The method of claim 26, wherein said hydratable keratin
material comprises sulfonate groups and is associated with one or
more metal ion species.
28. The method of claim 26, wherein said hydratable keratin
material is hydrated to form a hydrogel.
29. The method of claim 28, wherein said hydrogel is added to soil
at an amount between about 1% by weight to about 25% by weight.
30. The method of claim 28, wherein said hydrogel is added to soil
at amount between about 1% by weight to about 5% by weight.
31. The method of claim 26, wherein said hydratable keratin
material provides nitrogen to said soil.
32. A method for providing trace metal nutrients to soil comprising
addition to soil of an insoluble hydratable keratin material,
wherein said keratin material is associated with a plurality of
metal ion species.
33. The method of claim 32, wherein said keratin material comprises
sulfonate groups.
34. The method of claim 32, wherein said plurality of metal ion
species are selected from the group consisting of potassium,
sodium, copper, zinc, manganese, magnesium and calcium.
35. The method of claim 32, wherein said hydratable keratin
material is hydrated to form a hydrogel.
36. The method of claim 32, wherein said hydratable keratin
material provides nitrogen to said soil.
37. A method for the bioremediation of soil comprising addition to
soil of an insoluble hydratable keratin material, such that said
hydratable keratin material provides a nutrient source for
microorganisms capable of remediating soil contaminated with
environmental toxins.
38. The method of claim 37, wherein said keratin material comprises
sulfonate groups and is associated with one or more metal ion
species.
39. The method of claim 37, wherein said hydratable keratin
material is hydrated to form a hydrogel.
40. A method for the bioremediation of water contaminated with
environmental toxins comprising contacting an insoluble hydratable
keratin material with said contaminated water, wherein said keratin
provides a nutrient source for microorganisms capable of
remediating said water contaminated with environmental toxins.
41. The method of claim 40, wherein said water is groundwater.
42. The method of claim 40, wherein said water is
surface-water.
43. The method of claim 40, wherein said hydratable keratin
material comprises sulfonate groups and is associated with one or
more metal ion species.
44. A method for reducing the migration of environmental toxins in
soil comprising addition to soil of an insoluble hydratable keratin
material wherein said environmental toxins are adsorbed by said
keratin material.
45. The method of claim 44, wherein said hydratable keratin
material comprises sulfonate groups and is associated with one or
more metal ions species.
46. The method of claim 44, wherein said hydratable keratin
material provides a nutrient source for microorganisms capable of
remediating soil contaminated with environmental toxins.
47. A method for reducing the migration of environmental toxins in
groundwater comprising contacting a permeable barrier comprising an
insoluble hydratable keratin material with a plume of said
environmental toxins in groundwater.
48. The method of claim 47, wherein said keratin material comprises
sulfonate groups and is associated with one or more metal ion
species.
49. The method of claim 47, wherein said keratin material adsorbs
said environmental toxins.
50. The method of claim 47, wherein said environmental toxins bind
ionically to said keratin.
51. The method of claim 47, wherein said hydratable keratin
material provides a nutrient source for microorganisms capable of
remediating groundwater contaminated with environmental toxins.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The invention relates to compositions and methods of use for
soil amendments and bioremediation. More particularly, the
invention relates to compositions and methods of use of hydratable
keratin and keratin hydrogels as soil amendments and nutrient
sources for bioremediation.
[0003] 2. Description of Related Art
[0004] Keratin is a protein characterized by the prevalence of
cysteine which, when crosslinked, render most keratins insoluble
and environmentally robust in that they are resistant to hydrolysis
and dissolution. Nitrogen release from unmodified poultry feathers
has been reported as being too slow for use as a greenhouse
fertilizer (Williams and Nelson, 1992). But, production of a
feather meal by pressurized steam treatment, which breaks disulfide
bonds, results in an increased rate of nitrogen mineralization
(Hadas and Kautsky, 1994; Choi and Nelson, 1996). Feather meal also
releases organic sulfur as plant available SO.sub.4.sup.2-
(Wainwright et al., 1985). The availability of nitrogen may also be
enhanced by microbial action by composting keratin material.
Fertilizers have also utilized keratin materials after complete
hydrolysis to component amino acids. Chelates of such amino acids
have been used as trace element fertilizers (Baolin et al., 1995).
Mineral-organic fertilizers have also been prepared by mixing
minerals with keratin hydrolyzates.
[0005] A possible limitation on crude keratin fertilizer
preparations is that it may enrich the soil with keratolytic fungi
which may be pathogenic to man and animals (Wainwright et al.,
1985). Leather meal as a keratin source is also problematic because
of the possibility of incorporating tanning agents such as
chromium. Feather meal is malodorous, but can be made odor-free and
more easily composted by autoclave treatment (Choi and Nelson,
1996).
[0006] An adequate supply of water is essential for plant survival
and control of soil hydration is required for optimal plant growth.
A number of soil moisture systems require a monitoring system that
regulates an external water supply. Examples of such systems are
disclosed in U.S. Pat. Nos. 4,796,654 and 4,182,357. These systems
require a considerable amount of equipment, which will in turn
require maintenance. U.S. Pat. No. 5,814,123 discloses the addition
of humectants to enhance soil water retention. A humectant is a
compound or material that has an avidity for water and will promote
the retention of water in the soil. However, under some
circumstances such a compound may compete with plants for the
moisture retained in the soil. There is a continuing need for
materials that can both enhance water holding capability and
promote the retention of the moisture content of soil.
[0007] Bioremediation of soil utilizes microorganisms to degrade
environmental contaminants such as hydrocabons and halogenated
chemicals. The rate and extent of microbial degradation is limited
by the availability of nutrients in the contaminated soil. Without
added nutrients, the microbial degradation of environmental
contaminants can take an undesirably long time. Even with a
nutrient supply, in situ bioremediation can be a prolonged process,
and preferred characteristics of microbial nutrient sources are
that they are long acting, resistant to leaching, and biodegradable
such that undesirable residues from the nutrient source are not
left in the remediated soil. Groundwater is also amendable to
bioremediation and permeable bio-active barriers are used to act as
in situ bioremediation filters (Sutherson, 1997). Desirable
characteristics for such barrier constituents are water
permeability and a non-leachable nutrient source for support of a
microbial population.
[0008] Physical barriers are also used in containment of
environmental contaminants. Hair has been proposed as a physical
adsorbent for the remediation of oil spills. Keratin preparations
have also been disclosed as adsorbents for heavy metals (Japanese
Patent Abstracts JP53042281, JP4281856). Natural sorbents,
including keratin, have been used as physical sorbents for heavy
oil in bioremediation studies (Setti et al., 1999). The use of
sorbents increased the rate of n-alkane degradation, possibly due
to the formation of a water/cell/oil/sorbent interphase. Natural
sorbents are preferred because of their biodegradability.
SUMMARY
[0009] The present invention provides a soil amendment comprising a
chemically modified oxidized keratin that upon hydration forms a
hydrogel. The keratin hydrogel can increase the water retention
properties of soil and provide a source of organic and inorganic
nutrients. The hydrogel can also support the remediation of
contaminated soil and groundwater by adsorbing environmental toxins
and/or providing a nutrient source for microorganisms capable of
degrading the environmental toxins.
[0010] In the context of the present invention, the term
"hydratable keratin" and "hydratable keratin material" is a keratin
or keratin material that when hydrated forms a hydrogel.
[0011] One aspect of the present invention is a soil amendment
composition comprising an oxidized keratin hydrogel. The oxidized
keratin includes sulfonate groups and is associated with one or
more metal ion species. "Association" and "associated" are defined
in regard to the interaction between oxidized keratin and metal ion
species as including both ionic bonds, that is heteropolar bonds
between a negative anion and a positive cation, and chelates,
wherein a metal is bonded to another molecule by a covalent bonding
process or a coordination based on the donation of a free electron
pair of one atom. It is believed that the predominant bonding is
ionic and involves the sulfonic acid residues of the oxidized
keratin. In the practice of preferred embodiments of the invention,
one may select any suitable metal ion depending on the particular
application, or the particular needs of the soil to be treated. For
example, soils that are depleted in potassium or other plant
nutrients, or that may be depleted in a cation or metal such as
iron or zinc, for example, useful for microbial growth would be
treated with a soil amendment that contained one or more of those
metals or cations. In preferred embodiments, the one or more metal
ions or cations associated with the oxidized keratin may include,
but are not limited to potassium, sodium, copper, zinc, manganese,
magnesium, iron, calcium and combinations of these.
[0012] The keratin source for the soil amendment composition may be
any suitable source of keratin, either a soft keratin or a hard
keratin, and would include keratin derived from animal or human
hair, feathers, leather, skin, fur, animal hooves, animal or human
nails, beaks, claws, scales, feet and horns, and is preferably a
keratin that includes oxidizable amino acids such as cystines. In
certain embodiments, the soil amendment may also further comprise a
preservative such as an antifungal agent. Preservatives for use in
the practice of the invention would include, but are not limited to
tetraalkylammonium hydroxide, glutaraldehyde or formalin, and in
certain preferred embodiments tetraalkylammonium hydroxide is
used.
[0013] The soil amendment keratin hydrogel composition may be made
by the process comprising oxidizing disulfide bonds in a keratin
material with an oxidizing agent to obtain a keratin solid having
sulfonic acid residues. Any suitable oxidizing agent may be used in
the practice of the invention, including, but not limited to
hydrogen peroxide, alkali peroxides, peracids, perborates,
percarbonates, persulfates, hypochlorite-or chlorine dioxide, with
hydrogen peroxide or peracetic acid being the most preferred for
certain embodiments. The oxidized keratin solid is separated and
mixed with a water-miscible solvent containing one or more metal
ion or cationic species such that the one or more metal ions or
cationic species become associated with the oxidized keratin solid.
The water-miscible solvent may contain up to about 20 volume
percent of water. The water-miscible solvent is substantially
removed and the oxidized keratin is hydrated to form a hydrogel.
Any suitable water miscible solvent known in the art may be used in
the practice of the invention. Exemplary solvents include lower
alkyl alcohols such as methanol, ethanol, isopropanol, t-butanol or
n-propanol, for example. Other solvents that may be used include,
but are not limited to tetrahydrofuran, acetone, or acetonitrile,
and combinations. The foregoing solvents may be used with up to 20
volume percent of water.
[0014] Another aspect of the present invention is a process for
making a hydratable keratin-derived soil amendment material. The
keratin material may be any suitable source of keratin, either a
soft keratin or a hard keratin, and would include keratin derived
from animal or human hair, feathers, leather, skin, fur, animal
hooves, animal or human nails, beaks, claws, scales, feet and
horns, and is preferably a keratin that includes ionizable amino
acids. The process comprises the steps of oxidizing a keratin
material in a first solution with an oxidizing agent such that a
portion of the disulfide bonds of said keratin material are
oxidized to form sulfonic acid residues and forms an oxidized
keratin solid fraction. The oxidizing agent may be any suitable
agent, including, but not limited to hydrogen peroxide, alkali
peroxides, peracids, perborates, percarbonates, and persulfates.
The oxidized keratin is separated as a solid fraction from the
first solution and added to a second solution comprising one or
more metal ions dissolved in an neutral or slightly alkaline
water-miscible solvent. The water miscible solvent may be any
suitable solvent and in certain embodiments is a lower alkyl
alcohol selected from the group comprising methanol, ethanol,
isopropanol, t-butanol or n-propanol, and combinations of these.
Other solvents that may be used include, but are not limited to
tetrahydrofuran, acetone, or acetonitrile, and combinations of
these. The solvents may be used with up to 20 volume percent of
water. The second solution containing the oxidized keratin is
maintained for a time and temperature effective to cause an
association between the oxidized keratin and said one or more metal
ions. It is understood, of course, that the metal ion or other
cation in the second solution will associate with the oxidized
keratin material, and that one controls the types and amounts of
ions so associated by adjusting the concentration of such ions in
the second solution. The one or more metal ion or cationic species
associated with the oxidized keratin may be any suitable ions and
would include potassium, sodium, copper, zinc, manganese, magnesium
and calcium. The second solution is subsequently substantially
removed so as to obtain a hydratable keratin material. The process
may further comprise hydrating the keratin material to form a
hydrogel. It is also understood that hydration of the hydrogel may
include water soluble materials that are taken up in the hydrogel
with the water, and that such materials, including plant or
microbial nutrients, for example, would leach out of the hydrogel
over time.
[0015] One aspect of the invention is compositions and methods for
increasing the water retention properties of soil. One such method
comprises the addition of a hydratable keratin material as
described herein to soil. The keratin material may contain
sulfonate groups as described above, and may be associated with one
or more metal ion or cationic species. In the practice of this
method, one would normally mix the solid obtained after treatment
with water-miscible organic solvent solution described above in a
dried state with an appropriate amount of soil. The keratin
material may also be at least partially hydrated prior to addition
to the soil such that it is in a hydrogel state. The hydrogel may
be added to soil in any appropriate amount. For certain
embodiments, the hydrogel may contribute from 5% to about 95% of
the total weight of the mixture. It is also understood that the
keratin hydrogel material may serve as the total plant growth
support for certain plants, particularly for use in potted plants
and seedlings, or for the growth of epiphytes, for example. In
certain embodiments, the keratin material may contribute from about
1% to about 25%, or from about 1% to about 10%. or from about 1% to
about 5% of the total weight of the hydrogel/soil mixture. The
hydratable keratin material may also provide nitrogen to the soil
upon microbial degradation of the keratin material.
[0016] Another aspect of the present invention is a method for
providing trace metal nutrients to soil comprising addition to soil
of a hydratable keratin material. The hydratable keratin material
may contain sulfonate groups and be associated with a plurality of
metal ions species, and may be provided to the soil in either a
dried or hydrated (hydrogel) state. The plurality of metal ion
species may include, but is not limited to potassium, sodium,
copper, zinc, manganese, magnesium or calcium. Any metal or other
ion that associates with the hydrogel material may also be added to
the soil by this method. The hydratable keratin material may also
provide nitrogen or other nutrients to the soil upon degradation of
the keratin material.
[0017] An aspect of the present invention is also a method for
supporting the bioremediation of soil comprising addition of a
hydratable keratin material to soil, such that the keratin material
provides a nutrient source for microorganisms capable of
remediating soil contaminated with environmental toxins. The
hydratable keratin materials may comprise sulfonate groups and be
associated with one or more metal ion species, and may be added in
a dried state, or the hydratable keratin material may be hydrated
to form a hydrogel. In the practice of this embodiment, the
contaminated soil may be left in place, and the keratin material
added to it and mixed, or alternatively, the soil may be removed
from the site of contamination and treated at a remote location. A
bacterial culture capable of removing, digesting, or concentrating
a toxin or contaminate may be added directly to the soil, it may
pre-exist in the soil, or it may be added to the keratin material
prior to application to a material in need of remediation. All such
uses known to those of skill in the art would be encompassed by the
spirit and scope of the appended claims.
[0018] Another aspect of the present invention is a method for the
bioremediation of groundwater contaminated with environmental
toxins by providing a microorganism nutrient source comprising a
hydratable keratin material. The hydratable keratin material may
comprise sulfonate groups and may be associated with one or more
metal ion species. In the practice of the invention, contaminated
water may be mixed with a dried hydratable keratin material or a
hydrogel, or it may be contacted with a hydrated keratin hydrogel
material as in an in-line filter, or in a vessel.
[0019] Other aspects of the invention include methods for reducing
the migration of environmental toxins in soil and water by
providing a barrier against movement of contaminated or
contaminating materials. In the practice of the method, hydratable
keratin materials that may contain sulfonate groups and be
associated with one or more metal ion species, may be used as a
barrier. In certain embodiments, to reduce or control migration of
a soil contaminant, a ditch may be placed around a contaminated
area and filled with keratin hydrogel material. This practice
offers the advantage that as the keratin material may become
contaminated, it can be easily removed and replaced with fresh
keratin hydrogel material. In an alternative embodiment, reduction
of the migration of environmental toxins in groundwater may utilize
a permeable barrier which intersects the flow of a plume of toxins.
The hydratable keratin material may also provide a nutrient source
for microorganisms capable of remediating soil contaminated with
environmental toxins.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The following drawings form part of the present
specification and are included to further demonstrate certain
aspects of the present invention. The invention may be better
understood by reference to one or more of these drawings in
combination with the detailed description of specific embodiments
presented herein.
[0021] FIG. 1. Schematic of the oxidation of keratin cystine
residues to sulfonic acid groups.
[0022] FIG. 2. Typical titration curve for a one gram sample of
oxidized keratin derived from hair.
[0023] FIG. 3. Graph depicting the number of moles of sodium
hydroxide required to neutralize keratin derived from hair that has
been oxidized for varying times.
DETAILED DESCRIPTION
[0024] The copending invention disclosure U.S. application Ser. No.
09/394,782, filed Sep. 13, 1999, entitled "Water Absorbent Keratin
and Gel Formed Therefrom" describes the process by which a
hydratable keratin material is produced and is herein incorporated
in its entirety by reference. The keratin protein of the present
invention may be obtained from any natural keratin source such as
animal or human hair, feathers, leather, skin, fur, animal hooves,
animal or human nails, beaks, claws, scales, feet and horns, and
modified in such a way as to make the keratin protein highly water
absorbent. Hydratable keratin may be produced by cleaving a
substantial amount, but not all, of the of disulfide cystine
crosslinks. Disulfide scission may be accomplished by either
oxidative (Alexander and Erland, 1950) or reducing means (Wornell,
1948). Hydrogen peroxide or other oxidative treatment of hair
causes the disulfide linkages between cystine residues to convert
to sulfonic acid groups as shown in FIG. 1. The subsequent
treatment of the oxidized keratin with dilute alkali produces an
anionic polyelectrolyte form of keratin. If the oxidation
exhaustively converts the cystine amino acids into cysteic acid
then the keratin is usually rendered soluble by the alkali
treatment. If only a portion of the cystine amino acids are
converted to cysteic acid, the alkali treatment to neutrality will
produce an insoluble keratin material held together by the
remaining cystine disulfide bonds. In this case, the keratin solid
is converted to a material capable of absorbing a substantial
amount of water producing a material best described as a hydrogel.
Rather than being absorbent by capillary activity, this
polyelectrolytic form of keratin has the capability to form
hydrogen bonds with molecules such as water. The formation of these
hydrogen bonds provides the molecular network which, when swelled
with water, can form a hydrogel. The hydrogel of the present
invention is formed through the reactivity of a polyelectrolytic
form of keratin; however, this keratin is insoluble in water. The
nature of the cationic counterion to the hydratable keratin can be
tailored to suit the application. For example, exchanging the
acidic protons of the sulfonic acid with potassium hydroxide alkali
will produce a hydratable form of keratin that contains substantial
potassium. For this form of the hydratable keratin, the NPK value
would be approximately 12-0-5 which is appropriate for use as both
a water retaining additive as well as a high nitrogen and potassium
fertilizer. Other metal hydroxides are employed to provide trace
minerals as required for vigorous plant growth. Quaternary ammonium
compounds such as benzyltrimethylammonium hydroxide are employed to
delay microbial degradation or act as a preservative. Incorporation
of the hydrogel into soils at higher levels, greater than 5% by
weight for example, produces a hydrated soil that is substantially
devoid of pore volume.
[0025] Bioremediation is a treatment process that uses naturally
occurring microorganisms, such as bacteria and fungi, to degrade
hazardous substances into less toxic or nontoxic substances.
Microorganisms must be healthy and active in order for
bioremediation to take place. Thus bioremediation technologies are
required to assist the growth of the population of microorganisms
by creating appropriate environmental conditions and thereby
support the maximal rate of contaminant detoxification.
Bioremediation can utilize endogenous or exogenous microorganisms,
the latter of which may be genetically designed for bioremediation.
(Timmis and Pieper, 1999). The use of microbes isolated from soil
in the bioremediation nitro and halo organic compounds is described
in U.S. Pat. No. 5,571,705, which is herein incorporated by
reference.
[0026] Bioremediation of soil can be achieved either in situ or ex
situ. During in situ soil bioremediation, nutrients may be pumped
into the soil by injection wells. The introduction into the soil of
microorganisms and nutrients using a push rod or cylinder connected
to a delivery system is disclosed in U.S. Pat. No. 5,133,625, which
is incorporated herein by reference. If aerobic conditions are
required, oxygen can be provided by bioventing, i.e., blowing or
sucking air through soil, or injection of hydrogen peroxide. Ex
situ soil techniques can be faster and easier to control. The
excavated soil can be used in techniques such as slurry phase and
solid phase bioremediation. In a slurry phase bioreactor, the soil
is mixed with water and nutrients are added. A method for
slurry-phase bioremediation is disclosed in U.S. Pat. No.
5,232,596, which is incorporated herein by reference. Solid phase
bioremediation treats soil in above ground containment areas and
includes processes such as composting. Nutrients are mixed in with
the soil.
[0027] Groundwater can also be bioremediated in situ and ex situ.
In situ treatment can comprise placement of a porous barrier in a
trench that intercepts a groundwater plume. Microorganisms growing
in the barrier substrate can degrade contaminants as the
groundwater passes through the barrier. The barrier may also
function to adsorb contaminants. These trenches are typically used
in less permeable aquifers with shallow contamination. (Sutherson,
1997). As a nutrient source is required in such a barrier, a
permeable keratin hydrogel can provide a suitable substrate for the
biologically reactive porous barrier wall. Bioremediation of
groundwater can also be achieved by removal of groundwater by
extraction wells to an above-ground treatment system where
nutrients can be added. The remediated groundwater is returned via
an injection well. An in-well device for the bioremediation of
contaminants in groundwater is disclosed in U.S. Pat. No.
5,577,558, which is incorporated herein by reference.
[0028] In addition to groundwater, surface-water can also be
bioremediated. Surface-water includes, but is not limited to,
rivers, lakes and impoundments. Keratin hydrogel can be readily
contacted with surface-waters in situ or ex situ. The keratin
hydrogel may be enclosed in a water permeable container.
[0029] Since the keratin hydrogel is resistant to flow, it can
provide a long-acting gelled substrate that can be used to slow or
prevent the in situ migration of environmental toxins in soil or
groundwater, while providing a nutritive substrate for
naturally-occurring or introduced microorganisms capable of
remediating the toxic substances. The hydrogel is also amenable for
ex situ soil bioremediation, supplying both nutrients and
controlling the level of hydration of extracted soil. For treatment
of extracted groundwater, the water-permeable nature of the keratin
hydrogel can be exploited by using the gel as a physical support
and nutrient source for bioremediating microorganisms.
[0030] Bioremediation can also be used for the treatment of
industrial wastes prior to introduction into the environment.
Methods for the bioremediation of liquid and slurry hazardous waste
streams are disclosed in U.S. Pat. No. 5,922,204, which is
incorporated herein by reference. Keratin hydrogels can be utilized
in the bioremediation of waste streams, either in reaction vessels
or as in-line permeable barriers.
EXAMPLES
[0031] The following examples are included to demonstrate preferred
embodiments of the invention. It should be appreciated by those of
skill in the art that the techniques disclosed in the examples
which follow represent techniques discovered by the inventor to
function well in the practice of the invention, and thus can be
considered to constitute preferred modes for its practice. However,
those of skill in the art should, in light of the present
disclosure, appreciate that many changes can be made in the
specific embodiments which are disclosed and still obtain a like or
similar result without departing from the spirit and scope of the
invention.
Example 1
[0032] The hydrogel precursor is obtained by first treating human
hair with a combination of an oxidizing solution, heat and/or
exposure time. Said oxidizing solution is comprised of greater than
1 volume percent of oxidant such as hydrogen peroxide or peracetic
acid in water. Following oxidation, the resulting solid is
separated from the liquid and rinsed to remove the residual
oxidant. The solid is placed into boiling alcohol such as methanol
or ethanol and titrated to a pH of 7 by addition of a base such as
sodium hydroxide, using a pH electrode to determine the endpoint. A
typical titration curve for one gram of oxidized hair is shown in
FIG. 2. The amount of base required to neutralize the hair varies
dependent upon the conditions of the initial oxidation step, that
is as a function of the time, temperature and concentration of
oxidant used. Less vigorous oxidizing conditions will produce less
disulfide scission resulting in a product that will biodegrade at a
slower rate, but at the expense of the material's ability to absorb
water. FIG. 3 shows the amount of base required to neutralize a
gram of hair that has been oxidized for varying amounts of time.
The type and amounts of the various metal hydroxides will vary with
the application. For example, potassium hydroxide exchanged hair
would be suitable for blooming plants, while magnesium exchanged
oxidized keratin would be appropriate for growing new foliage. The
types of metals exchanged can be tailored to fit a particular
requirement or application.
[0033] After a period of boiling not less than 10 minutes, the
neutral or slightly alkaline solution is cooled and stirred at room
temperature for not less than 1 hour. The resulting solid material
is removed from solution, rinsed with alcohol to remove excess
base, and dried under vacuum. This process results in the formation
of ionic salts which make the keratin more reactive toward
water.
[0034] The dried protein is brittle and can be shredded into small
fibers or ground into a powder. The modified keratin has
demonstrated the capability of absorbing up to 15 to 20 times its
weight of water. The water molecules penetrate the keratin fibers
or powder and form ionic and hydrogen bonds to the protein
molecules. The bonds provide linkages that result in the formation
of a stable network. Excess water surrounds the keratin molecules
and causes the material to swell into a gel.
Example 2
Release of Inorganic Nutrients
[0035] The rate of release of inorganic nutrients from the keratin
soil amendments of the present invention can be readily measured.
An appropriate amount of keratin hydrogel (e.g., 1-10% by weight)
is added to soil. Soil samples are incubated for an appropriate
time period, up to 60 to 90 days, at constant temperature (e.g.,
22.degree. C. which approximates room temperature). Control soil
samples lacking the amendment are also included. Samples are
contained so as to allow for gas exchange without substantial water
loss. The moisture content of soil can be established by
differential gravimetric analysis before and after drying or by
commercially available moisture meters. A method and device for
monitoring the moisture in soil is disclosed in U.S. Pat. No.
5,341,673, herein incorporated by reference.
[0036] The release of inorganic nutrients is measured at various
time points. NO.sub.3.sup.-, NH.sub.4.sup.+ and SO.sub.4.sup.2- can
be extracted by using 10 volumes of distilled water, 1.5M potassium
chloride, or 0.1 M lithium chloride respectively (Wainwright et
al., 1985). The soil extracts are shaken for 15 to 30 minutes and
then filtered. Total nitrogen can be measured by the Kjedahl
procedure (Eastin, 1978). NO.sub.3.sup.- and NH.sub.4.sup.+ can be
measured calorimetrically using chromotropic acid and indophenol
blue methods respectively, while SO.sub.4.sup.2- can be measured
turbdimetrically (Hesse, 1970). The amount of inorganic nutrients
can be expressed as per unit wet weight or dry weight of soil.
Example 3
Measurement of Microbial Biomass
[0037] The microbial biomass can be measured in keratin amendment
treated soil or in keratin hydrogel alone. The microbial biomass
may be the result of endogenous microorganisms in soil samples or
the result of soil or keratin hydrogel inoculated with specific
microorganisms. Soil samples or keratin hydrogel alone are kept as
described in Example 2 for periods up to 60 days. At various time
points the total bacterial count, proteolytic bacteria,
cellulose-hydrolyzing bacteria, Azobacteria, fungi or actynomycetes
counts can be determined by the methods described by Wollum (1982).
Microbial biomass-nitrogen can be determined by the method of
Brookes et al. (1985). Measurement of other specific microorganisms
or biomass parameters can be achieved by using appropriate
methodologies either known or available to one of ordinary skill in
the art.
[0038] All of the compositions and methods disclosed and claimed
herein can be made and executed without undue experimentation in
light of the present disclosure. While the compositions and methods
of this invention have been described in terms of preferred
embodiments, it will be apparent to those of skill in the art that
variations may be applied to the compositions and/or methods and in
the steps or in the sequence of steps of the methods described
herein without departing from the concept, spirit and scope of the
invention. More specifically, it will be apparent that certain
agents that are chemically or physiologically related may be
substituted for the agents described herein while the same or
similar results would be achieved. All such similar substitutes and
modifications apparent to those skilled in the art are deemed to be
within the spirit, scope and concept of the invention as defined by
the appended claims.
References
[0039] The following references, to the extent that they provide
exemplary procedural or other details supplementary to those set
forth herein, are specifically incorporated herein by
reference.
[0040] Alexander and Erland, "Structure of wool fibers", Nature,
166: 396, 1950
[0041] Baolin et al., "Study on a new type of amino-acid chelate
trace fertilizer", Huaxe Gongye Yu Gongcheng, 13:42, 1996.
[0042] Brookes et al., "Chloroform fumigation and release of soil
nitrogen: A rapid direct extraction method to measure microbial
biomass nitrogen in soil", Soil Biol. Biochem. 17:837, 1985.
[0043] Choi and Nelson, "Developing a slow release nitrogen
fertilizer from organic sources: II using poultry feathers", J.
Amer. Soc. Hort. Sci. 121:634, 1996.
[0044] Eastin, "Total nitrogen determination for plant materials
containing nitrate", Anal. Biochem., 85:591, 1978.
[0045] Hadas and Kautsky, "Feather meal, a semi-slow-release
nitrogen fertilizer for organic farming", Fertilizer Res., 38:165,
1994.
[0046] Hesse, A Textbook of Soil Chemical Analysis, J. Murray,
London, 1970.
[0047] Setti et al., "Enhanced degradation of heavy oil in an
aqueous system by a Pseudomonas sp. in the presence of natural and
synthetic sorbents", Bioresource Technology, 67:191, 1999.
[0048] Sutherson, Remediation Engineering: Design Concepts. Lewis
Publishers, 1997.
[0049] Timmis and Pieper, "Bacteria designed for bioremediation",
Trends Biotechnol., 17:200, 1999.
[0050] Wainright et al., Fertilizer potential of some commercially
available forms of keratin and microbial biomass", Enzyme Microb.
Tech. 7:108, 1985.
[0051] Williams and Nelson, "Low, controlled nutrient availability
provided by organic materials for chrysanthemum", J. Amer. Soc.
Hort. Sci. 117:422, 1992.
[0052] Wollum, "Cultural methods for soil microorganisms", In:
Methods of Soil Analysis, Agronomy 9, Part 2, (Page et al. eds, 2nd
edn) pp 791-796, American Society of Agronomy, 1982.
[0053] Wornell, J. Tex. Inst., 39:219, 1948
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