U.S. patent application number 10/550223 was filed with the patent office on 2007-07-12 for high capacity solid filtration media.
Invention is credited to William G. England.
Application Number | 20070157810 10/550223 |
Document ID | / |
Family ID | 38229680 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070157810 |
Kind Code |
A1 |
England; William G. |
July 12, 2007 |
High capacity solid filtration media
Abstract
A high capacity filtration media, method of preparing the media,
and method of treating a fluid stream with the media are provided.
The media contain a porous substrate impregnated with high
concentrations of a permanganate. Preferably, the media includes a
porous substrate impregnated with at least about 8% permanganate by
weight. The media can optionally contain sodium bicarbonate.
Improved capacity for the removal of undesirable compounds such as
ethylene, formaldehyde, hydrogen sulfide and methyl mercaptan are
achieved.
Inventors: |
England; William G.;
(Suwanee, GA) |
Correspondence
Address: |
JOHN S. PRATT, ESQ;KILPATRICK STOCKTON, LLP
1100 PEACHTREE STREET
ATLANTA
GA
30309
US
|
Family ID: |
38229680 |
Appl. No.: |
10/550223 |
Filed: |
November 25, 2003 |
PCT Filed: |
November 25, 2003 |
PCT NO: |
PCT/US03/37894 |
371 Date: |
June 9, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60428958 |
Nov 25, 2002 |
|
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60512841 |
Oct 20, 2003 |
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Current U.S.
Class: |
95/285 |
Current CPC
Class: |
B01J 20/043 20130101;
B01D 53/02 20130101; B01D 2251/10 20130101; B01J 20/06 20130101;
B01D 53/565 20130101; B01D 53/58 20130101; B01D 53/52 20130101;
B01J 20/04 20130101; B01J 20/3204 20130101; B01D 53/485 20130101;
B01D 39/2068 20130101; B01D 53/72 20130101; B01J 20/0222 20130101;
B01J 20/3236 20130101; B01D 53/48 20130101; B01J 20/16 20130101;
B01D 53/62 20130101; B01J 20/08 20130101; B01J 2220/56 20130101;
B01J 20/3078 20130101; B01D 2251/304 20130101; B01J 20/12 20130101;
B01D 53/54 20130101; B01D 53/82 20130101; B01D 53/685 20130101 |
Class at
Publication: |
095/285 |
International
Class: |
B01D 46/00 20060101
B01D046/00 |
Claims
1. A composition comprising a porous substrate impregnated with a
permanganate, wherein the permanganate is a permanganate salt
having a solubility in water greater than that of potassium
permanganate, wherein the concentration of permanganate salt in the
composition is at least approximately 8% permanganate salt by
weight.
2. The composition of claim 1, wherein the permanganate salt is
selected from the group consisting of sodium permanganate,
magnesium permanganate, calcium permanganate, barium permanganate,
lithium permanganate, or a combination thereof.
3. The composition of claim 1, wherein the composition comprises at
least about 13 to about 25% permanganate salt by weight.
4. The composition of claim 1, wherein the composition comprises at
least about 15 to about 20% permanganate salt by weight.
5. The composition of claim 1, wherein the composition comprises at
least about 18 to about 19% permanganate salt by weight.
6. The composition of claim 1, wherein the composition further
comprises t least about 5% and about 25% water by weight.
7. The composition of claim 1, wherein the permanganate salt
comprises odium permanganate.
8. The composition of claim 1, further comprising a gas evolving
material selected from a carbonate compound, a bicarbonate
compound, or a combination thereof.
9. The composition of claim 1, wherein the porous substrate
comprises activated alumina, a silica gel, a zeolite, a
zeolite-like mineral, kaolin, an adsorbent clay, activated bauxite,
or a combination thereof, and wherein the porous substrate is
between about 40 and about 80% by weight of the composition.
10. The composition of claim 9, wherein the zeolite or zeolite-like
mineral is selected from amicite, analcime, pollucite, boggsite,
chabazite, edingtonite, faujasite, ferrierite, gobbinsite,
harmotome, phillipsite, clinoptilolite, mordenite, mesolite,
natrolite, garronite, perlialite, barrerite, stilbite, thomsonite,
kehoeite, pahasapaite, tiptopite, hsianghualite, lovdarite,
viseite, partheite, prehnite, roggianite, apophyllite, gyrolite,
maricopaite, okenite, tacharanite, tobermorite, or a combination
thereof.
11. The composition of claim 8, wherein the gas-evolving material
comprises sodium bicarbonate and the porous substrate comprises
activated alumina or a combination of activated alumina and at
least one zeolite or zeolite-like mineral.
12. The composition of claim 11, wherein the concentration of
sodium bicarbonate is between about 5 and about 25% by weight of
the composition.
13. A method of treating a contaminated fluid stream comprising
contacting the contaminated fluid stream with a solid filtration
composition such that contaminants are removed from the fluid
stream, wherein the solid filtration composition comprises a porous
substrate impregnated with a permanganate, wherein the permanganate
is a permanganate salt having a solubility in water greater than
that of potassium permanganate, wherein the concentration of
permanganate salt in the composition is at least approximately 8%
permanganate salt by weight.
14. The method of claim 13, wherein the concentration of
permanganate is between about 13 and about 25% by weight of the
composition.
15. The method of claim 13, wherein the concentration of
permanganate is between about 15 and about 20% by weight of the
composition.
16. The method of claim 13, wherein the concentration of
permanganate is between about 18 and about 19% by weight of the
composition.
17. The method of claim 13, wherein the composition further
comprises a gas-evolving material having a concentration between
about 5 and about 25% by weight of the composition.
18. The method of claim 13, wherein the contaminated fluid stream
contains hydrogen sulfide and the removal capacity of the solid
filtration unit is at least about 16%
19. The method of claim 13, wherein the contaminated fluid stream
contains ethylene and the removal capacity of the solid filtration
unit is at least about 4%
20. The method of claim 13, wherein the contaminated fluid stream
contains formaldehyde and the removal capacity of the solid
filtration unit is at least about 4%
21. The method of claim 13, wherein the contaminated fluid stream
contains methyl mercaptan and the removal capacity of the solid
filtration unit is at least about 6%
22. A method of preparing a solid filtration composition
comprising: a) mixing a permanganate and a porous substrate,
wherein the permanganate is a permanganate salt having a solubility
in water greater than that of potassium permanganate; b) spraying
the mixture with water; c) forming the mixture into at least one
cohesive porous unit; and d) curing the unit at a temperature of
from about 100.degree. F. to about 200.degree. F. until the
concentration of water is at least about 5% by weight of
composition, and the concentration of permanganate is at least
about 8% by weight of composition.
23. The method of claim 22, wherein the unit is cured until the
concentration of permanganate is between about 13 and about 25% by
weight of the composition.
24. The method of claim 22, wherein the unit is cured until the
concentration of permanganate is between about 15 and about 20% by
weight of the composition.
25. The method of claim 22, wherein the unit is cured until the
concentration of permanganate is between about 18 and 19% by weight
of the composition.
26. The method of claim 22, wherein the unit is cured until the
water concentration is between about 5% and about 25%.
27. The method of claim 22, wherein the porous substrate comprises
activated alumina, a silica gel, a zeolite, a zeolite-like mineral,
kaolin, an adsorbent clay, activated bauxite, or a combination
thereof.
28. The method of claim 22, further comprising mixing the
permanganate and porous substrate with a gas-evolving material,
wherein the gas-evolving material is selected from a carbonate
compound, a bicarbonate compound, or a combination thereof.
29. The method of claim 22, further comprising a gas-evolving
material, wherein the concentration of gas-evolving material is
between about 5 and about 25% by weight of the composition.
30. The method of claim 22, wherein the gas-evolving material is
sodium bicarbonate and the porous substrate is activated alumina or
a combination of activated alumina and at least one zeolite or
zeolite-like mineral.
31. The method of claim 30, wherein the zeolite or zeolite-like
mineral is selected from amicite, analcime, pollucite, boggsite,
chabazite, edingtonite, faujasite, ferrierite, gobbinsite,
harmotome, phillipsite, clinoptilolite, mordenite, mesolite,
natrolite, garronite, perlialite, barrerite, stilbite, thomsonite,
kehoeite, pahasapaite, tiptopite, hsianghualite, lovdarite,
viseite, partheite, prehnite, roggianite, apophyllite, gyrolite,
maricopaite, okenite, tacharanite, tobermorite, or a combination
thereof.
32. The method of claim 22, wherein the concentration of the porous
substrate comprises between about 40% and about 60%.
33. The composition of claim 1, wherein the solubility of the
permanganate salt is greater than 6.5 g/100 ml in weight, at
20.degree. C.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to a composition and
method for the removal of compounds having disagreeable odors,
toxic properties or corrosive properties from gaseous streams. The
invention more particularly relates to the use in filter beds of a
high capacity solid filtration media containing a substrate
impregnated with a permanganate.
BACKGROUND OF THE INVENTION
[0002] The removal of toxic, corrosive and odorous gases can be
accomplished by a number of techniques. These may include wet
scrubbing, incineration, and removal via gas-phase air filtration
using a variety of dry scrubbing adsorptive, absorptive, and/or
chemically impregnated media. As opposed to these other methods,
gas-phase air filtration does not require the consumption of large
quantities water or fuel. Dry-scrubbing media can be engineered
from a number of common adsorbent materials with or without
chemical additives for the control of a broad spectrum of gases or
tailored for specific gases.
[0003] In contrast to the reversible process of physical
adsorption, chemical adsorption, also referred to as chemisorption,
is the result of chemical reactions on the surface of the media.
This process is specific and depends on the physical and chemical
nature of both the media and the gases to be removed. Some
oxidation reactions can occur spontaneously on the surface of the
adsorbent, however, a chemical impregnant is usually added to the
media. The impregnant imparts a higher contaminant removal capacity
and can lend some degree of specificity. Although some selectivity
is apparent in physical adsorption, it can usually be traced to
purely physical, rather than chemical, properties. In
chemisorption, stronger molecular forces are involved, and the
process is generally instantaneous and irreversible.
[0004] Undesirable airborne compounds, including sulfur compounds,
such as hydrogen sulfide and dimethyl sulfide, ammonia, chlorine,
formaldehyde, urea, carbon monoxide, oxides of nitrogen,
mercaptans, amines, isopropyl alcohol and ethylene, occur in a
number of environments, where most are primarily responsible for
the presence of disagreeable odors, or irritating or toxic gases.
Such environments include petroleum treatment and storage areas,
sewage treatment facilities, hospitals, morgues, anatomy
laboratories, animal rooms, and pulp and paper production sites,
among others. These undesirable compounds may be bacterial
breakdown products of higher organic compounds, or simply
byproducts of industrial processes.
[0005] Hydrogen sulfide ("H.sub.2S"), a colorless, toxic gas with a
characteristic odor of rotten eggs, is produced in coal pits, gas
wells, sulfur springs, and from decaying organic matter containing
sulfur. Controlling emissions of this gas, particularly from
municipal sewage treatment plants, has long been considered
desirable. More recently, protecting electronic apparatus from the
corrosive fumes of these compounds has become increasingly
important. Furthermore, H.sub.2S is flammable.
[0006] Ammonia ("NH.sub.3") is also a colorless gas. It possesses a
distinctive, pungent odor and is a corrosive, alkaline gas. The gas
is produced in animal rooms and nurseries, and its control also has
long been considered important.
[0007] Chlorine ("Cl.sub.2") is a greenish-yellow gas with a
suffocating odor. The compound is used for bleaching fabrics,
purifying water, treating iron, and other uses.
[0008] Control of this powerful irritant is necessary for the
well-being of those who work with it or are otherwise exposed to
it. At lower levels, in combination with moisture, chlorine has a
corrosive effect on electronic circuitry, stainless steel and the
like.
[0009] Formaldehyde ("OCH.sub.2") is a colorless gas with a
pungent, suffocating odor. It is present in morgues and anatomy
laboratories, and because it is intensely irritating to mucous
membranes, its control is necessary.
[0010] Urea ("OC(NH.sub.2).sub.2") is present in toilet exhaust and
is used extensively in the paper industry to soften cellulose. Its
odor makes control of this compound important.
[0011] Carbon monoxide ("CO"), an odorless, colorless, toxic gas,
is present in compressed breathing air. Oxygenation requirements
for certain atmospheres, including those inhabited by humans,
mandate its control.
[0012] Oxides of nitrogen, including nitrogen dioxide ("NO.sub.2"),
nitric oxide ("NO"), and nitrous oxide ("N.sub.2O"), are compounds
with differing characteristics and levels of danger to humans, with
nitrous oxide being the least irritating oxide. Nitrogen dioxide,
however, is a deadly poison. Control of pollution resulting from
any of these oxides is desirable or necessary, depending on the
oxide.
[0013] Mercaptans and amines, including methyl mercaptan
("CH.sub.3SH"), butyl mercaptan ("C.sub.4H.sub.9SH") and methyl
amine ("CH.sub.3NH.sub.2"), are undesirable gases present in
sewerage odor. The control of these gases is desired for odor
control.
[0014] Isopropyl alcohol ("(CH.sub.3).sub.2CHOH") is a flammable
liquid and vapor. Inhalation of the vapor is known to irritate the
respiratory tract. Furthermore, exposure to high concentrations of
isopropyl alcohol can have a narcotic effect, producing symptoms of
dizziness, drowsiness, headache, staggering, unconsciousness and
possibly death. The control of this vapor in print processing and
industrial synthesis is desired.
[0015] Ethylene ("C.sub.2H.sub.4") is a colorless, flammable gas.
It is a simple asphyxiant that accelerates the maturation or
decomposition of fruits, vegetables, and flowers. Control of this
compound prolongs the marketable life of such items.
[0016] The airborne compounds described above can have a
detrimental effect on the local environment. For example,
acidification is caused by emissions of sulfur dioxide and nitrogen
compounds (nitrogen oxides and ammonia), which in turn cause acid
rain. Furthermore, nitrogen oxides and volatile organic compounds
from vehicular traffic, electricity and heat production, as well as
from industrial facilities may, under certain conditions,
contribute to the formation of photochemical oxidants, among which
ozone is the dominating substance. Ozone is a colorless gas that
forms when nitrogen oxides mix with hydrocarbons in the presence of
sunlight. In addition to causing environmental damage, ozone poses
a health hazard, particularly for children, the elderly and
individuals with asthma or lung disease.
[0017] Attempts have been made to provide solid filtration media
for removing the undesirable compounds described above from fluid,
or moving, streams, such as gas or vapor streams. Desired features
of such media are a high total capacity for the removal of the
targeted compound so that the media lasts longer and need not be
replaced frequently, a high efficiency in removing the compound
from an air stream contacting the media so that the compound is
removed quickly, and a high ignition temperature
(non-flammability). High capacity and high efficiency are, in turn,
directly affected by the porosity and pore structure of the solid
filtration media, while the capacity, efficiency and ignition
temperature are all affected by the specific composition of the
media.
[0018] Although a variety of permanganate-impregnated substrates
are known for removing undesirable contaminants from fluid streams,
these known impregnated substrates all demonstrate a limited
capacity and, therefore, a low efficiency for the removal of
undesirable compounds from the streams. These limitations arise to
a large extent from an insufficient porosity of the solid
filtration media or a clogging of pores with byproducts formed by
reactions of the impregnate with the contaminant. This results in
the currently available media not meeting the needs of various
industries.
[0019] Therefore, what is needed is a high efficiency, high
capacity, low flammability permanganate-impregnated substrate for
the removal of undesirable compounds from gas streams. Such an
impregnated substrate needs to be long-lasting, requiring fewer
replacements and thereby minimizing replacement and maintenance
costs. Also needed is a high capacity impregnated substrate that
may be used in small filter beds, and therefore may allow the
treatment of fluid streams where there are significant space
limitations.
SUMMARY OF THE INVENTION
[0020] High capacity solid filtration media, methods of preparing
the same and methods of treating a fluid stream with the solid
filtration media are provided. The solid filtration media described
herein are useful for removing or reducing undesirable contaminants
from a gaseous fluid stream.
[0021] Generally described, the high capacity solid filtration
media include a porous, impregnated substrate having high levels of
impregnate. The impregnate is a permanganate, preferably a
permanganate salt having high water solubility, such as sodium
permanganate or lithium permanganate. A gas-evolving or
gas-producing material such as sodium bicarbonate may also be
included in the media. In contrast to presently available
filtration media, the high capacity solid filtration media
described herein contain levels of permanganate approximately 8% or
higher, thereby providing an increased efficiency for removing
undesirable gaseous compounds from a fluid stream, particularly
compounds such as ethylene, formaldehyde and methyl mercaptan from
gaseous streams by exhibiting a higher capacity for contaminant.
For example, when used to remove ethylene from a gaseous stream,
the media described herein utilizing sodium permanganate have an
ethylene capacity of approximately 9%, whereas currently available
potassium permanganate-impregnated media exhibit a maximum ethylene
capacity of only approximately 3%.
[0022] The present invention addresses an existing need in the
industry by providing a high capacity, low flammability
permanganate-impregnated substrate for the removal of undesirable
contaminants from gas streams. The permanganate-impregnated
substrate provides a long lasting filtration media that can be
replaced less frequently, thereby minimizing maintenance and
replacement costs. Due to its high capacity, the impregnated
substrate described herein may be used in small filter beds,
thereby allowing the treatment of fluid streams where significant
space limitations exist. The filtration media described herein
yield an equivalent or superior capacity over activated carbon
adsorbents and are much less expensive and considerably less
flammable than activated carbon adsorbents.
[0023] Generally described, the filtration media contain at least
approximately 8% by weight of media composition of a permanganate,
wherein the permanganate has a higher solubility in water than that
of potassium permanganate, and a porous substrate, wherein the
permanganate impregnates the porous substrate. The composition
typically also contains at least approximately 5% water by weight
of media composition. Preferably, the permanganate is a highly
water soluble permanganate salt such as sodium permanganate or
lithium permanganate. The porous substrate is typically selected
from, but not limited to, activated alumina, silica gel, a zeolite,
adsorbent clay, kaolin, activated bauxite, or combinations thereof,
the preferred porous substrate being alumina or an alumina-zeolite
mix.
[0024] Preferred solid filtration media contain from approximately
8 to approximately 25% permanganate, between approximately 5 and
25% water, and a porous substrate. More preferred solid filtration
media contain from approximately 15 to approximately 20%
permanganate, between approximately 5 and 25% water, and a porous
substrate. Most preferably, the solid filtration media contain from
approximately 18 to approximately 19% permanganate, between
approximately 5 and 25% water, and a porous substrate. All of the
above percentages are by weight of the entire composition and, as
described above, the permanganate has a higher solubility in water
than that of potassium permanganate.
[0025] In another embodiment, the media further contain a
gas-evolving material, such as a carbonate compound, a bicarbonate
compound, or a combination thereof, that function by producing a
gas (typically CO.sub.2) upon heating. For example, when the
composition further contains sodium bicarbonate, the sodium
bicarbonate is present between approximately 5 to 25%, and
preferably is between about 15 to 20% by weight of the entire
composition.
[0026] The high capacity solid filtration media composition
described above are produced by mixing water, a permanganate, and a
substrate, and then forming the mixture into at least one cohesive
porous unit. The unit is then cured at a temperature of from about
100.degree. F. to about 200.degree. F., until the concentration of
water is at least about 5% by weight of the composition, and the
concentration of the permanganate is at least about 8% by weight of
the composition.
[0027] In accordance with a preferred method of making the solid
filtration media, an aqueous solution containing the permanganate
is sprayed onto the porous substrate. In an alternative aspect,
water is combined with a dry mixture containing the permanganate
and the substrate. In yet another aspect, an aqueous solution
containing the permanganate is sprayed onto a dry mixture
containing the permanganate and the substrate. Optionally, sodium
bicarbonate may be added either to the dry mixture, to the water,
or to both in the method of preparing the filtration media.
[0028] Preferably, the unit formed as described above is cured
until the concentration of water is from about 5 to about 25% by
weight of the composition, and the concentration of the
permanganate is from about 8 to about 25% by weight of the
composition. Preferably, where sodium bicarbonate has been added to
the composition, the unit formed is cured until the concentration
of sodium bicarbonate is between 15 to 20% by weight. More
preferably, the unit is cured until the concentration of the
permanganate is from about 15 to about 20% by weight of the
composition. Most preferably, the unit is cured until the
concentration of the permanganate is from about 18 to about 19% by
weight of the composition.
[0029] Yet another aspect of the present invention is a method of
treating a contaminated fluid stream with the high capacity solid
filtration media described herein. This method comprises contacting
the contaminated fluid stream with the solid filtration media to
remove contaminant.
[0030] The high capacity filtration media, the method of
preparation, and the method of use provide improved efficiency and
capacity in removing contaminants, particularly odor-causing
contaminants, from gas streams.
[0031] Accordingly, it is an object of the present invention to
provide a high capacity solid filtration media that efficiently
removes undesirable compounds from an air stream to reduce odors,
minimize the corrosion of metals or electronics, and to provide a
nontoxic or nonirritating breathing environment for humans and
animals.
[0032] It is another object of the present invention to provide a
high capacity solid filtration media that is long-lasting and
requires minimal maintenance or replacement.
[0033] It is yet another object of the present invention to provide
a solid filtration media having a high ignition temperature, and
therefore, limited flammability.
[0034] It is also an object of the present invention to provide an
improved solid filtration media that is inexpensive to manufacture
and use.
[0035] It is another object of the present invention to provide a
solid filtration media having such a high capacity for removing
undesirable compounds that less media needs to be utilized,
therefore allowing the use of smaller air filtration units.
[0036] It is yet another object of the present invention to provide
a simple, inexpensive method of making an improved solid filtration
media having a high efficiency and a high total capacity for the
removal of an undesirable compound.
[0037] It is a further object to provide a rapid, efficient and
inexpensive method of treating a contaminated air or gas stream
with a solid filtration media.
[0038] These and other objects, features and advantages of the
present invention will become apparent after a review of the
following detailed description of the disclosed embodiments and the
appended claims.
DETAILED DESCRIPTION
[0039] High capacity solid filtration media, methods of preparing
the same, and methods of treating a fluid stream with the solid
filtration media are provided. The solid filtration media can be
used to remove or reduce undesirable compounds, or contaminants,
from a gaseous fluid stream. The solid filtration media contain
permanganate and a porous substrate. Typically, the media also
contain water. A gas-evolving material such as sodium bicarbonate
may also be included. In some embodiments, at least one zeolite is
optionally included in the media. The media contain significantly
higher levels of permanganate than previously believed to be
possible.
[0040] Generally described, the filtration media contain a
substrate impregnated with high levels of permanganate. The
permanganate is a highly water soluble permanganate having a
solubility in water greater than that of potassium permanganate.
The filtration media include at least about 8% permanganate by
weight of the composition. The permanganate is preferably a
permanganate salt such as, but not limited to, sodium permanganate
("NaMnO.sub.4"), magnesium permanganate ("Mg(MnO.sub.4).sub.2"),
calcium permanganate ("Ca(MnO.sub.4).sub.2"), barium permanganate
("Ba(MnO.sub.4).sub.2"), and lithium permanganate ("LiMnO.sub.4").
More preferably, the permanganate salt is sodium permanganate
(commercially available from chemical suppliers such as Carus
Chemical Co., Peru, Ill.) or lithium permanganate. Most preferably,
the permanganate is sodium permanganate due to its inexpensive
commercial availability. The concentration of the permanganate in
the media is typically from about 8 to about 25%, more preferably
from approximately 15 to approximately 20%, and most preferably
from approximately 18 to approximately 19%, by weight of the
composition.
[0041] The porous substrate may be selected from the group
consisting of, but not limited to, activated alumina
(Al.sub.2O.sub.3) (UOP Chemical, Baton Rouge, La.), silica gels (J.
M. Huber, Chemical Division, Havre De Grace, Md.), zeolites (Steel
Head Specialty Minerals, Spokane, Wash.), kaolin (Englehard Corp.,
Edison, N.J.), adsorbent clays (Englehard Corp., Edison, N.J.), and
activated bauxite. A preferred porous substrate is alumina.
Preferably, the concentration of substrate in the filtration media
is from about 40 to 80%, and most preferably is from about 60 to
75% in the absence of sodium bicarbonate and from about 40 to 60%
if the media contain sodium bicarbonate.
[0042] Another preferred porous substrate is a combination of
alumina and a zeolite, in which up to about 50% by weight of the
porous substrate combination is a zeolite. Though not intending to
be bound by this statement, it is believed that zeolites further
control the moisture content of the filtration media by attracting
and holding water, which functions to keep more of the impregnate
in solution. This effect, in turn, is believed to enhance the high
capacity and improved efficiency of the filtration media. As used
herein, the term zeolite includes natural silicate zeolites,
synthetic materials and phosphate minerals that have a zeolite-like
structure. Examples of zeolites that can be used in this media
include, but are not limited to, amicite (hydrated potassium sodium
aluminum silicate), analcime (hydrated sodium aluminum silicate),
pollucite (hydrated cesium sodium aluminum silicate), boggsite
(hydrated calcium sodium aluminum silicate), chabazite (hydrated
calcium aluminum silicate), edingtonite (hydrated barium calcium
aluminum silicate), faujasite (hydrated sodium calcium magnesium
aluminum silicate), ferrierite (hydrated sodium potassium magnesium
calcium aluminum silicate), gobbinsite (hydrated sodium potassium
calcium aluminum silicate), harmotome (hydrated barium potassium
aluminum silicate), phillipsite (hydrated potassium sodium calcium
aluminum silicate), clinoptilolite (hydrated sodium potassium
calcium aluminum silicate), mordenite (hydrated sodium potassium
calcium aluminum silicate), mesolite (hydrated sodium calcium
aluminum silicate), natrolite (hydrated sodium aluminum silicate),
amicite (hydrated potassium sodium aluminum silicate), garronite
(hydrated calcium aluminum silicate), perlialite (hydrated
potassium sodium calcium strontium aluminum silicate), barrerite
(hydrated sodium potassium calcium aluminum silicate), stilbite
(hydrated sodium calcium aluminum silicate), thomsonite (hydrated
sodium calcium aluminum silicate), and the like. Zeolites have many
related phosphate and silicate minerals with cage-like framework
structures or with similar properties as zeolites, which may also
be used in place of, or along with, zeolites. These zeolite-like
minerals include minerals such as kehoeite, pahasapaite, tiptopite,
hsianghualite, lovdarite, viseite, partheite, prehnite, roggianite,
apophyllite, gyrolite, maricopaite, okenite, tacharanite,
tobermorite, and the like.
[0043] The concentration of water in the filtration media is
typically at least approximately 5 to 25%, preferably from
approximately 10 to 25%. One of ordinary skill in the art will
understand that the concentration of free water in the filtration
media may be altered by the conditions present, such as the
humidity and the temperature, during its storage and use.
[0044] Preferably, the solid filtration media includes from
approximately 8 to 25% permanganate, from about 5 to 25% water, and
from approximately 40 to 80% substrate, by weight of the
composition. More preferably, the media contain from approximately
15 to 20% permanganate, from approximately 5 to 25% water, and from
approximately 40 to 80% substrate, by weight. Most preferably, the
solid filtration media contain from approximately 18 to 19%
permanganate, from approximately 10 to 25% water, and from
approximately 40 to 60% substrate, by weight. As described above,
the permanganate is ideally sodium permanganate due to its high
solubility in water and inexpensive commercial availability.
[0045] The gas-evolving material of the filtration media described
herein is a material that produces or releases a gaseous substance
upon heating, for example during the curing step of forming the
filtration media. The bubbles formed in this heating process are
instrumental in enhancing and controlling the pore structure of the
filtration media. The gas-evolving material is usually selected
from a carbonate compound, a bicarbonate compound, or a combination
thereof, that functions by producing carbon dioxide gas upon
heating. A preferred gas-evolving material is sodium bicarbonate,
because of its smooth release of carbon dioxide, and its relatively
low cost. However, other bicarbonates and carbonates can be used in
this media, the selection of which is understood by one of ordinary
skill in the art. The number and size of the pores produced from
heating the gas-evolving material is related to the concentration
of the gas-evolving material in the solid filtration media, the
temperature of curing, and the time of curing. Thus, increasing the
concentration of sodium bicarbonate in the composition increases
the pore size and number, helps reduce and prevent clogging of the
pore structure, enhances the retention of water, and sustains the
concentration of the permanganate in the filtration media.
[0046] In a preferred embodiment, the filtration media composition
includes a permanganate, water, a substrate and sodium bicarbonate
("NaHCO.sub.3") (Rhone-Poulenc, Chicago Heights, Ill.), wherein the
concentration of sodium bicarbonate is from approximately 5 to 25%,
and preferably from 15 to 20%, by weight. In the embodiments where
the filtration media contain sodium bicarbonate, the preferred
concentration of alumina is from approximately 40 to 60%.
[0047] It is to be understood that, when referring to the relative
weight of components, the water referred to in the present
specification, examples, and tables is defined as the free water,
and does not include the bound water in the substrate. Free water
is driven off by an oven at approximately 200.degree. F., but if
left in the substrate it is available for the oxidation reaction.
In contrast, bound water is not driven out or evaporated except by
a kiln at about 1800 to 2000.degree. F., and the bound water
functions by holding the substrate together. Bound water is not
available for reaction with the undesirable contaminants.
[0048] It is also to be understood that the term permanganate as
used quantitatively in the present specification, examples, and
tables represents the permanganate salt, not the permanganate ion,
MnO.sub.4.sup.-. Therefore, the percent ranges of permanganates in
compositions in the present specification denote the percent of the
permanganate salt in the composition, not the percent of the
permanganate ion in the composition.
[0049] Terms such as "filtration media", "adsorbent composition,"
"chemisorbent composition," and "impregnated substrate" are all
interchangeable, and denote a substance that is capable of reducing
or eliminating the presence of unwanted contaminants in fluid
streams by the contact of such a substance with the fluid stream.
It is to be understood that the term "fluid" is defined as a liquid
or gas capable of flowing, or moving in a particular direction, and
includes gaseous, aqueous, organic containing, and inorganic
containing fluids.
Solid Filtration Media Preparation Methods
[0050] Also provided is a method of preparing high capacity solid
filtration media. The method includes mixing water, a permanganate,
an optional gas-evolving material, and a porous substrate, and then
forming the mixture into at least one cohesive porous unit. The
unit is then typically cured at a temperature of from about
100.degree. F. to about 200.degree. F., until the concentration of
water is at least about 5% by weight of the composition, and the
concentration of the permanganate is at least about 8% by weight of
the composition. The size and shape of the cohesive porous unit is
not critical. Any size and shape of a porous unit known in the art
to reduce or eliminate undesirable contaminants from fluid streams
when in contact with the unit may be used. Preferably, the porous
unit is a nominal 1/8'' diameter round pellet.
[0051] The method provided herein preferably includes forming an
aqueous solution containing the permanganate and optional
gas-evolving material and then mixing the aqueous permanganate
solution with the porous substrate. To dissolve and maintain the
permanganate in solution, the aqueous solution should be heated to
approximately 160.degree. to 200.degree. F., and preferably to
approximately 180.degree. to 190.degree. F.
[0052] In another embodiment, the method includes forming a dry
mixture containing the permanganate and the porous substrate, and
then adding water to the dry mixture.
[0053] In yet another embodiment, the method includes forming a dry
mixture containing the permanganate, the optional gas-evolving
material, and the porous substrate; forming a separate aqueous
solution containing the permanganate and the optional gas-evolving
material, and then mixing the aqueous solution with the dry
mixture. Optionally, the gas-evolving material such as sodium
bicarbonate may be added either to the dry mixture, to the water,
or to both in the above methods of preparing the filtration
media.
[0054] Preferably, the unit formed is cured until the concentration
of water is from about 5 to about 25%, most preferably from about
10 to about 25% by weight of the composition; the concentration of
the permanganate is at least about 8 to about 25% by weight of the
composition, more preferably from about 15 to about 20%, and most
preferably from about 18 to about 19%; and the concentration of the
gas-evolving material is from about 5 to about 25% by weight of the
composition, most preferably from about 15 to 20% by weight of the
composition, after curing. The presence of a gas-evolving material
such as sodium bicarbonate allows for a lower curing temperature,
such as about 130.degree. to 140.degree. F., in contrast to the
conventional curing temperature of about 200.degree. F.
[0055] The impregnation treatment of the activated starting
material in accordance with the present method has not been found
to be critical with respect to the particular sequence in which the
dry mix is impregnated with moisture and impregnates. The above
combinations may be mixed in any manner which effectively produces
the desired filtration media. Impregnation may be carried out
simply by immersing and soaking the solid combination in a volume
of impregnate solution. Also, the impregnate solution may be passed
through the combination rather than being used as a static
immersion treatment. However, it has been found that a preferred
method of impregnation is spray addition in which an impregnate
solution is sprayed onto a dry combination being tumbled in a
mixer. This method of impregnation has been described in U.S. Pat.
No. 3,226,332, which is herein incorporated by reference in its
entirety. Other methods of impregnating the combinations will
suggest themselves as equally appropriate, and these are included
within the scope of the present method.
[0056] In one embodiment utilizing the above spray addition method,
the aqueous impregnate solution of permanganate is sprayed onto a
dry combination of gas-evolving material, such as sodium
bicarbonate, and a porous substrate, such as activated alumina. For
example, the dry combination preferably contains between
approximately 80 to 85% activated alumina and between approximately
15 to 20% of sodium bicarbonate.
[0057] The concentration of the permanganate may vary in the
solution to be sprayed onto the dry combination. For example, to
produce a solid filtration medium containing approximately 20%
permanganate, an aqueous solution containing approximately 40% of
permanganate, at between approximately 160.degree. F. to
200.degree. F., and preferably at about 180.degree. F. to
190.degree. F. should be sprayed on the dry combination of
gas-evolving material and porous substrate being tumbled in a
mixer. Also, to produce a solid filtration medium containing
approximately 8-9% permanganate, a solution of approximately 18%
permanganate at between approximately 160.degree. F. to 200.degree.
F., and preferably at about 180.degree. F. to 190.degree. F. should
be sprayed on the dry combination of gas-evolving material and
porous substrate being tumbled in a mixer. Any concentration of
permanganate in the aqueous solution which is effective to yield
the composition described herein may be used. Further, where the
permanganate is either in the dry feed mixture or in both the
aqueous solution and the dry feed mixture, any concentration of
permanganate in the dry mixture and/or the aqueous solution which
is effective to produce the composition described herein may be
used. For example, the media may be used to fill perforated modules
to be inserted into air ducts in a manner known in the art.
Contaminant Removal Methods
[0058] Also provided is a method of treating a contaminated fluid
stream using the high capacity solid filtration media described
herein or produced by the process described above. This method
involves contacting the contaminated fluid stream with the solid
filtration composition provided herein. Typically, the undesired
contaminants will be removed from air, especially from air admixed
with effluent gas streams resulting from municipal waste treatment
facilities, paper mills, petrochemical refining plants, morgues,
hospitals, anatomy laboratories, and hotel facilities, and so
forth. Methods of treating gaseous or other fluid streams are well
known in the art. As the method of treating fluid streams is not
critical to the present invention, any method known in the art of
treating fluid streams with the media described herein may be
used.
[0059] The composition described herein is useful for removing
undesired contaminants from gaseous streams. Undesirable airborne
compounds to be removed using the high capacity filtration media
include, but are not limited to, sulfur compounds (such as hydrogen
sulfide and dimethyl sulfide), ammonia, chlorine, formaldehyde,
urea, carbon monoxide, oxides of nitrogen, mercaptans (such as
methyl mercaptan), amines, isopropyl alcohol and ethylene.
Typically, contaminants to be removed by employing the media
described herein include, but are not limited to, ethylene,
formaldehyde and methyl mercaptan The concentrations of undesirable
contaminants in the gaseous streams is not considered critical to
the process of contaminant removal, nor is the physical and
chemical makeup of the gas stream considered critical. Even
concentrations of these undesirable compounds in gas streams
resulting in levels lower than one ppb of the compounds passing
through a solid filtration media bed per minute may be removed.
[0060] However, it has been found that flow rates of the gas stream
being contacted with the bed of filtration media affect the
breakthrough capacities of the media. The preferred flow rate is
between 10 and 750 ft/min, and most preferably is between 60 and
100 ft/min, flowing perpendicularly to the face of the bed.
[0061] While not intending to be bound by the following statement,
it is believed that it may be necessary that certain oxidizing
conditions prevail while using the solid filtration media described
herein. The extent of oxidation may affect the degree of
purification achieved. Preferably, oxygen is present in the gas
stream being treated, at least in small amounts. This oxygen
content is readily found in the gas stream, if air constitutes a
sufficient portion of the gas stream being treated. If oxygen is
totally absent or present in insufficient amounts, oxygen may be
independently introduced into the gas stream being treated. A
number of factors affect the amount of oxygen, which may be
required for maximum removal of the contaminants in a gas stream in
accordance with the present method, including the concentration and
absolute amount of compounds being removed from the gas stream
being treated.
[0062] With respect to the amount of compound removed, it is
believed that the following factors affect the process: the basic
degree of attraction of the activated substrate for the compound;
the pore structure and pore size distribution; the size of the
substrate; the specific surface area of the substrate as affected
by the number and size of pores; the surface characteristics of the
substrate; the amount of permanganate present; the amount of
gas-evolving material present in the composition, which affects the
number, size, and perhaps structure of pores; and the amount of
water present.
[0063] The filtration media provided herein is appropriately used
alone in filter beds for the removal of undesirable compounds. It
is also appropriate, however, to use the composition in conjunction
with filter beds containing other filtration media, and also in
conjunction with mechanical or electrostatic filters. Any such
additional filters may be placed either upstream (before the media
described herein with respect to the effluent gas being treated) or
downstream.
[0064] The above invention significantly increases the efficiency
and capacity of impregnated porous substrates (filtration media) to
remove certain undesired compounds from gaseous streams over the
capacity of impregnated substrates currently available. Therefore,
the lifetime of a specific quantity of the high capacity filtration
media will be much longer than the same quantity of the currently
available filtration media.
[0065] The extension of the lifetime of the filtration products
will significantly reduce the purchasing, servicing, and
installation costs of consumers and businesses. Also, the enhanced
efficiency of the media allows for a new line of products, which
are compact versions of currently available units, but have the
same performance as the larger, currently available units. The
capability of creating significantly smaller filtration units is
useful for providing efficacious air filtration in space-limited
quarters, which previously could not utilize the larger, currently
available units.
[0066] Also, the filtration media described herein is less
expensive than other filtration media having a roughly equivalent
capacity. For example, the media of the present invention has a
capacity equivalent or superior to the contaminant capacity of
activated carbon adsorbents, particularly in respect to ethylene
and formaldehyde contaminants. However, the media provided herein
is considerably less expensive than activated carbon
adsorbents.
[0067] Further, the filtration media provided herein is safe as it
is not flammable, in contrast to carbon-containing filtration
products. This characteristic of the presently provided filtration
media is significant to industries that manufacture or process
flammable, fume producing materials, such as the petroleum industry
for example.
[0068] In the high capacity filtration media described herein, the
use of a highly water soluble permanganate, having a water
solubility higher than that of potassium permanganate, allows for
an increase in the concentration of permanganate in the media. This
increased concentration of permanganate greatly increases the
removal capacity of the media for contaminants. When performing
accelerated capacity tests as described in the examples below, the
filtration media is examined at 100% efficiency until the
efficiency drops to a pre-determined level, in this case 99.5%
efficiency. Once this breakthrough is achieved the test is
complete, and removal capacity can then be calculated. The capacity
level is inherently linked to efficiency, because it is determined
in association with the time taken for the efficiency to drop to
99.5%. Currently available potassium permanganate impregnated
alumina media has a capacity of approximately 3% for the removal of
ethylene. In contrast, the high capacity filtration media described
herein containing approximately 60% activated alumina,
approximately 15-20% water, and 19-20% sodium permanganate,
exhibited an ethylene capacity of approximately 9%. Capacity tests
were performed by challenging a known quantity of the selected
solid filtration media with 1.0% (by volume) ethylene gas at a
constant flow rate and monitoring the concentration of ethylene in
the gas stream exiting the solid filtration media. The accelerated
removal capacity test is fully described in U.S. Pat. No.
6,004,522, which is herein incorporated by reference in its
entirety.
[0069] The high capacity of the solid filtration media described
herein is not limited to the removal of ethylene from a gaseous
stream. Indeed, high capacity is similarly achieved for other
gaseous contaminant such as hydrogen sulfide, formaldehyde and
methyl mercaptan. The results of these investigations are presented
in the Examples, below.
[0070] Although the precise mechanisms by which the high capacity
media operates are not understood or fully appreciated, and its
scope is not bound by the following theory, it is believed that the
oxidation reactions between the permanganate and the undesirable
contaminants occur primarily near the surface of the filtration
media, rather than deep within its pores. Therefore the media most
likely perform at optimal levels when the oxidative capabilities of
the surface are continually regenerated. It is believed that the
oxidative capability of the surface of the media is regenerated by
the flow or migration of permanganate from the center of the media
to the surface of the media while the products of the oxidation
reactions flow or migrate from the surface of the media to the
center of the media. It is also believed that the higher the
concentration of permanganate at the surface of the media, the
higher the capacity and efficiency of the media.
[0071] Furthermore, the fluidity of the permanganate solution
directly affects the flow and thus the quantity of the permanganate
reaching the surface of the media. Therefore, the media work well
when an elevated concentration of free water is maintained in the
media so that the permanganate solution maintains a high level of
fluidity and readily flows to the surface of the media thereby
maximizing the efficiency and capacity of the media. A liquid path
thus should be established between the interior of the pores and
the surface of the media. In this regard, the improved pore
structure provided by the addition of a gas-evolving material to
the filtration media is believed to enhance the ready flow of
permanganate solution. This is contrary to conventional theories,
which teach a need for penetration of the gaseous contaminants into
the pores of the substrate.
[0072] This theory, presented above, explains why the capacity and
efficiency of the traditional filtration media could not surpass
the capacity and efficiency obtained at the potassium permanganate
concentrations of 4-5%. As stated above, previously, various
attempts were made to impregnate the media with higher quantities
of potassium permanganate, however, the majority of the free water
has always been removed from these media. The efficiency and
capacity of these highly impregnated potassium permanganate media
remained constant or decreased relative to the capacity achieved by
media impregnated with 4-5% permanganate. There are three reasons
for the failure of the highly impregnated media currently available
to obtain higher results. First, the high concentration of
permanganate and the low concentration of water causes the
permanganate to crystallize and clog the pores of the substrate
thereby blocking the flow of permanganate to the surface of the
media. Second, the crystallized permanganate remains in the center
of the media and therefore cannot move to the surface of the media
to oxidize contaminants. Third, it is difficult for any
permanganate that may be in solution to move to the surface of the
media as the permanganate solution is very concentrated and has a
low level of fluidity. It is for these reasons that maintaining an
elevated level of water in the media is believed to be useful for
improved filtration media, and is included in the present
invention. It is also believed that the unprecedented improvement
in solid filtration media of this invention is due to recent
advances in the preparation and supply of commercially available
permanganates. Historically these permanganates are supplied either
as granular crystals or relatively low aqueous concentrations.
Potassium permanganate is known to crystallize in high
concentration, as frequently demonstrated in the literature.
Concentrated aqueous potassium permanganate (20%) can also
precipitate during curing, and ultimately clog the pores of
filtration media. However, a permanganate having a water solubility
greater than that of potassium permanganate, such as sodium
permanganate, is miscible in water in all proportions (by
comparison, potassium permanganate solubility is approximately 6.5
g/100 ml by weight, at 20.degree. C.). Due in part to the important
difference in solubility, it is now possible to incorporate
substantially higher concentrations (>20%) of permanganates,
such as sodium permanganate, than previously obtained, ultimately
yielding an increased removal capacity of contaminates from gaseous
streams. Furthermore, the significant increase in removal capacity
of ethylene contaminants is due in part to the increased
concentration of permanganate, but also due to the formation of
relatively small non-volatile waste products (CO.sub.2 and
H.sub.2O) which are released from the solid filtration media,
effectively providing additional active surface area for multiple
reactions with other gaseous contaminants.
[0073] The following examples will serve better to illustrate the
high capacity of the solid filtration media described herein for
the removal of contaminants in gas streams. It should be noted that
the continuous flow systems described in several of the following
examples all were operated at a relative humidity of 40-50%.
EXAMPLE 1
Preparation of Filtration Media Containing 13% Sodium
Permanganate
[0074] A sodium permanganate impregnated alumina composition is
prepared as follows.
[0075] A dried feed mix is prepared by combining, by weight, 80-85%
alumina, and 15-20% sodium bicarbonate. The dry feed mixture is
sprayed with a heated aqueous sodium permanganate solution at 180
to 190.degree. F. while being tumbled in a tumble mill. The
resulting pellets are dried at 130 to 140.degree. F. until the
pellets contain about 20 to 25% free water.
[0076] To prepare solid filtration media containing approximately
13% sodium permanganate by dry weight, the aqueous sodium
permanganate solution preferably contains approximately 26% sodium
permanganate by weight. It is to be understood that the aqueous
sodium permanganate solution is sprayed onto the dry feed while the
dry mix is rolled in the pelletizing disk as described in U.S. Pat.
No. 3,226,332, incorporated herein by reference.
EXAMPLE 2
Preparation of Filtration Media Containing 4-5% Potassium
Permanganate
[0077] A 4-5% potassium permanganate impregnated alumina
composition was prepared as follows.
[0078] A dry feed mix, consisting of 100% alumina, was sprayed with
a heated aqueous potassium permanganate solution at 180 to
190.degree. F. while the dried feed was tumbled in a tumble mill.
The resulting pellets were then dried at 130 to 140.degree. F.
until the pellets contained about 20 to 25% free water.
[0079] To prepare solid filtration media containing approximately
4-5% potassium permanganate by dry weight, the aqueous potassium
permanganate solution preferably contained approximately 10%
potassium permanganate by weight. It is to be understood that the
aqueous potassium permanganate solution was sprayed onto the dry
feed while the dry mix was rolled in the pelletizing disk as
described in U.S. Pat. No. 3,226,332.
EXAMPLE 3
Preparation of Filtration Media Containing 19-20% Sodium
Permanganate
[0080] A 19-20% sodium permanganate impregnated alumina composition
was prepared as follows.
[0081] A dried feed mix, consisting of 100% alumina, was sprayed
with a heated aqueous sodium permanganate solution at 180 to
190.degree. F. while the dried feed was being tumbled in a tumble
mill. The resulting pellets were then dried at 130 to 140.degree.
F. in air until the pellets contained about 20 to 25% free
water.
[0082] To prepare a solid filtration media containing approximately
19-20% sodium permanganate, by dry weight, the aqueous solution
preferably contained approximately 40% sodium permanganate, by
weight. It is to be understood that the aqueous potassium
permanganate solution was sprayed on to the dry feed while the dry
feed was rolled in the pelletizing disk as described in U.S. Pat.
No. 3,226,332.
EXAMPLE 4
Preparation of Additional Permanganate-Impregnated Substrates
[0083] Using the methods described in Examples 2 and 3, above, the
following compositions, by dry weight, were also prepared.
TABLE-US-00001 TABLE I Composition of Solid Filtration Media Sample
Number Substrate % NaMnO.sub.4 % KMnO.sub.4 % H.sub.2O 4A Alumina
4-5 0 15-20 4B Alumina 0 8-9 15-20 4C Alumina 8-9 0 15-20
[0084] The dry feed mix, consisting of 100% alumina, was mixed in a
tumbling mill and sprayed with the appropriate amount of aqueous
potassium permanganate or aqueous sodium permanganate solution,
while tumbling, in the manner described in U.S. Pat. No. 3,226,332.
Curing was carried out as in Examples 2 or 3 to provide the cured
pellets as a strong, non-dusting filter media suitable for
placement in filter beds.
EXAMPLE 5
Standard Accelerated Test Method for Capacity Determination of
Gas-Phase Air Filtration Media.
[0085] The following accelerated test method is useful for
determining the capacity of removal of various gas-phase air
filtration media when subjected to a flowing gas stream containing
high levels of contaminant(s). Low-level challenge testing of
gas-phase air filtration media, whether full-scale or small-scale,
usually takes long periods of time to obtain the desired results.
The following method provides an accelerated test for determining
the removal capacities of various media by exposing them to high
levels of contaminants.
[0086] The method is briefly summarized as follows: a known volume
of media is placed in an adsorption tube and exposed to a known
concentration (usually 1% by volume) of contaminant gas(es) in a
tempered, humidified, clean air system. The gas stream is
calibrated to deliver a total flow rate of 1450.+-.20 ml/min. The
removal capacity is calculated as the amount (in grams) of
contaminant removed from the air stream per volume (cubic
centimeters) of media at a 50 parts per million ("ppm")
breakthrough.
[0087] More specifically, the air utilized must be tempered,
humidified, clean, oil-free, and compressed. Accordingly, the air
must be passed through a bed of activated carbon followed by a
filter bed containing sodium permanganate impregnated alumina
pellets. Each filter bed should contain at least 300 ml (18.3 cu.
in.) of media for each liter per minute (0.035 cfm) of air flow.
The media in each filter bed should be changed before each
test.
[0088] Media samples are preferably obtained from unopened original
manufacturer's shipping or storage containers chosen at random
whenever possible. The entire container, whenever possible or
practical, should be sampled by taking small amounts of media from
throughout the container and combining them into one larger
sample.
[0089] The sample should be thoroughly mixed before being analyzed.
Guidance on sampling may be obtained from ASTM Standard E300,
entitled Recommended Practice for Sampling Industrial Chemicals. If
a test is to be run comparing media of the same size or different
sizes, the sample collected may be screened through the appropriate
sieves to sort the media by size.
[0090] Using an appropriate sampling method, obtain a
representative sample of media (approximately 400 grams should be
sufficient) and determine its apparent density as per ASTM 2854, or
an equivalent method. Obtain an adsorption tube which is a
cylindrical tube where glass wool and/or beads are optionally
placed below the media, and the media and optional glass wool or
beads are supported by stainless steel mesh, a perforated slotted
glass disc, or a perforated slotted ceramic disc positioned below
the media and glass wool or beads. After the adsorption tube having
the glass wool or glass beads has been calibrated for the volume of
a known depth of media, weigh the adsorption tube to the nearest
1.0 mg. Fill the adsorption tube to the desired depth via
alternately filling and gently tamping the tube to eliminate any
dead space until the desired depth is reached. Weigh the filled
adsorption tube to the nearest 1.0 mg.
[0091] The filled media tube is arranged such that a mixture of air
and contaminated gas enters the bottom of the tube, flows through
the glass wool or beads, flows through the filtration media, and is
then analyzed by a gas analyzer. Leaks in the gas system should be
checked for and eliminated before beginning the analysis of the
sample. Rotameters, analyzers, recorders, etc. should be calibrated
over appropriate ranges according to the manufacturer's
instructions or other standard methods such as ASTM Standard D3195,
before any media is introduced into the system. Also, air and gas
flow requirements should be determined and checked against supply
capabilities to assure proper air and gas flows to the system.
[0092] Once the adsorption tube is in position, start the flow of
the mixture of contaminated gas and air and record the time, or
time the test using a stop watch. Continue the flow of the mixture
of gas and air until a breakthrough of 50 ppm is observed or
indicated by the gas analyzer. Record the time at breakthrough. It
is preferable to use a gas analyzer capable of variable scale
readouts to 50 ppm (.+-.5 ppm), having specific or multiple gas
capabilities.
[0093] The data obtained from the above analysis will yield the gas
capacity of the media tested using the following equation: GAS
CAPACITY (GM/CC)=(K.times.10.sup.-5)(C)(F)(t.sub.b)/V where:
[0094] K=1.52 for H.sub.2S, 2.86 for SO.sub.2, 3.17 for Cl.sub.2,
2.15 for CH.sub.3SH, 0.76 for NH.sub.3, 2.05 for NO.sub.2, 1.16 for
C.sub.2H.sub.4, 1.34 for OCH.sub.2, and 1.39 for NO.
C=Concentration of challenge gas in air stream, Volume %.
F=Total stream flow rate, cc/min.
t.sub.b=Time to 50 ppm breakthrough, minutes.
V=Volume of the adsorption tube media column, cc.
EXAMPLE 6
Capacity of Permanganate Impregnated Alumina Pellets in the
Presence of H.sub.2S.
[0095] The results of tests comparing the capacities of various
solid filtration media are summarized in Table II below. The
capacity tests were performed by challenging a known quantity of
the selected solid filtration media with 1.0% hydrogen sulfide gas
at a constant flow rate and monitoring the concentration of
hydrogen sulfide in the gas stream exiting the solid filtration
media as described in Example 5. TABLE-US-00002 TABLE II Hydrogen
Sulfide Capacity Tests for Various Media Media % KMnO.sub.4 %
NaMnO.sub.4 % H.sub.2S capacity Example 2 4-5 0 8 Example 3 0 19-20
17 Sample 4A 0 4-5 8 of Example 4 Sample 4B 8-9 0 16 of Example 4
Sample 4C 0 8-9 16 of Example 4
EXAMPLE 7
Capacity of Permanganate Impregnated Alumina Pellets in the
Presence of Ethylene.
[0096] The results of tests comparing the capacities of various
solid filtration media are summarized in Table III below. The
capacity tests were performed by challenging a known quantity of
the selected solid filtration media with 1.0% ethylene gas at a
constant flow rate and monitoring the concentration of ethylene in
the gas stream exiting the solid filtration media as described in
Example 5. TABLE-US-00003 TABLE III Ethylene Capacity Tests for
Various Media Media % KMnO.sub.4 % NaMnO.sub.4 % Ethylene capacity
Example 2 4-5 0 2 Example 3 0 19-20 9 Sample 4A 0 4-5 2 of Example
4 Sample 4B 8-9 0 3 of Example 4 Sample 4C 0 8-9 4 of Example 4
EXAMPLE 8
Capacity of Permanganate Impregnated Alumina Pellets in the
Presence of Formaldehyde.
[0097] The results of tests comparing the capacities of various
solid filtration media are summarized in Table IV below. The
capacity tests were performed by challenging a known quantity of
the selected solid filtration media with 1.0% formaldehyde gas at a
constant flow rate and monitoring the concentration of formaldehyde
in the gas stream exiting the solid filtration media as described
in Example 5. TABLE-US-00004 TABLE IV Formaldehyde Capacity Tests
for Various Media Media % KMnO.sub.4 % NaMnO.sub.4 % formaldehyde
capacity Example 2 4-5 0 2 Example 3 0 19-20 8 Sample 4A of 0 4-5 2
Example 4 Sample 4B of 8-9 0 3 Example 4 Sample 4C of 0 8-9 4
Example 4
EXAMPLE 9
Capacity of Permanganate Impregnated Alumina Pellets in the
Presence of Methyl Mercaptan.
[0098] The results of tests comparing the capacity of solid
filtration media of the present invention are summarized in Table V
below. The capacity tests were performed by challenging a known
quantity of the selected solid filtration media with 1.0% methyl
mercaptan gas at a constant flow rate and monitoring the
concentration of methyl mercaptan in the gas stream exiting the
solid filtration media as described in Example 5. TABLE-US-00005
TABLE V Methyl Mercaptan Capacity Tests for Various Media % Methyl
Mercaptan Media % KMnO.sub.4 % NaMnO.sub.4 capacity Example 2 4-5 0
3 Example 3 0 19-20 11 Sample 4A of 0 4-5 3 Example 4 Sample 4B of
8-9 0 5 Example 4 Sample 4C of 0 8-9 6 Example 4
[0099] It should be understood, of course, that the foregoing
relates only to certain embodiments of the present invention and
that numerous modifications or alterations may be made therein
without departing from the spirit and the scope of the invention.
All of the publications or patents mentioned herein are hereby
incorporated by reference in their entireties.
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