U.S. patent application number 12/423678 was filed with the patent office on 2009-10-22 for method for neutralization, adsorption, and absorption of hazardous or otherwise undesired compounds in a tobacco product.
This patent application is currently assigned to NANOSCALE CORPORATION. Invention is credited to David Brotton, Olga B. Koper.
Application Number | 20090260645 12/423678 |
Document ID | / |
Family ID | 41199694 |
Filed Date | 2009-10-22 |
United States Patent
Application |
20090260645 |
Kind Code |
A1 |
Brotton; David ; et
al. |
October 22, 2009 |
METHOD FOR NEUTRALIZATION, ADSORPTION, AND ABSORPTION OF HAZARDOUS
OR OTHERWISE UNDESIRED COMPOUNDS IN A TOBACCO PRODUCT
Abstract
A tobacco product comprising nanocrystalline particles and
methods of reducing the levels of undesirable compounds in tobacco
smoke are provided. The nanocrystalline particles are effective
sorbents of numerous toxic compounds released by burning tobacco
and may be incorporated into the tobacco itself, incorporated into
a filter element, or incorporated into the fibers of a wrapping
paper.
Inventors: |
Brotton; David; (Manhattan,
KS) ; Koper; Olga B.; (Manhattan, KS) |
Correspondence
Address: |
HOVEY WILLIAMS LLP
10801 Mastin Blvd., Suite 1000
Overland Park
KS
66210
US
|
Assignee: |
NANOSCALE CORPORATION
Manhattan
KS
|
Family ID: |
41199694 |
Appl. No.: |
12/423678 |
Filed: |
April 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61044758 |
Apr 14, 2008 |
|
|
|
Current U.S.
Class: |
131/342 ;
131/347; 131/360; 131/365; 977/903 |
Current CPC
Class: |
A24B 15/28 20130101;
A24B 15/287 20130101; A24B 15/286 20130101; A24B 15/246 20130101;
A24B 15/245 20130101; A24D 3/16 20130101 |
Class at
Publication: |
131/342 ;
131/347; 131/360; 131/365; 977/903 |
International
Class: |
A24D 3/06 20060101
A24D003/06; A24F 47/00 20060101 A24F047/00; A24B 1/00 20060101
A24B001/00; A24D 1/02 20060101 A24D001/02 |
Claims
1. A tobacco product comprising nanocrystalline particles and
tobacco.
2. The tobacco product of claim 1, wherein said tobacco product is
a cigarette or cigar.
3. The tobacco product of claim 1, wherein said tobacco and said
nanoparticles are contained within a paper wrapping.
4. The tobacco product of claim 3, wherein said nanocrystalline
particles are dispersed within said tobacco.
5. The tobacco product of claim 3, wherein said nanocrystalline
particles are loaded upon or contained within the fibers of said
paper wrapping.
6. The tobacco product of claim 1, wherein said tobacco product
comprises a fibrous filter portion.
7. The tobacco product of claim 6, wherein said nanocrystalline
particles are included within said filter portion and are
configured to contact and adsorb smoke and/or toxic materials
produced from the burning of said tobacco.
8. The tobacco product of claim 1, wherein said nanocrystalline
particles are selected from the group consisting of the oxides,
hydroxides, halides, carbonates, and phosphates of metals,
metalloids, and combinations thereof.
9. The tobacco product of claim 8, wherein said nanocrystalline
particles are selected from the group consisting of the oxides,
hydroxides, halides, carbonates, nitrates, sulfates, and phosphates
of transition metals, alkali metals, alkaline earth metal,
lanthanide metals, and combinations thereof.
10. The tobacco product of claim 1, wherein said nanocrystalline
particles have an average surface area of at least 20
m.sup.2/g.
11. The tobacco product of claim 1, wherein said nanocrystalline
particles have an average crystallite size of between about 2 to
about 25 nm.
12. The tobacco product of claim 1, wherein said nanocrystalline
particles are amorphous and have an average crystallite size of
less than 2 nm.
13. The tobacco product of claim 1, wherein said tobacco product
comprises between about 0.001% to about 2% by weight of said
nanocrystalline particles based upon the weight of the entire
tobacco product.
14. A method of reducing the level of reducing the level of
undesirable components in tobacco smoke from a tobacco product
comprising the step of incorporating a quantity of nanocrystalline
particles into said tobacco product.
15. The method of claim 14, wherein said nanocrystalline particles
are combined with said tobacco prior to creation of said tobacco
product.
16. The method of claim 14, wherein said tobacco product is a
cigarette or cigar.
17. The method of claim 14, wherein at least a portion of said
nanocrystalline particles are incorporated into a filter portion of
said tobacco product.
18. The method of claim 14, wherein said nanocrystalline particles
are loaded upon or contained within the fibers of a paper wrapping
of said tobacco product.
19. The method of claim 14, wherein said nanocrystalline particles
are selected from the group consisting of the oxides, hydroxides,
halides, carbonates, and phosphates of metals, metalloids, and
combinations thereof.
20. The method of claim 19, wherein said nanocrystalline particles
are selected from the group consisting of the oxides, hydroxides,
halides, carbonates, and phosphates of transition metals, alkali
metals, alkaline earth metal, lanthanide metals, and combinations
thereof.
21. The method of claim 14, wherein said nanocrystalline particles
have an average surface area of at least 20 m.sup.2/g.
22. The method of claim 14, wherein said nanocrystalline particles
have an average crystallite size of between about 2 to about 25
nm.
23. The method of claim 14, wherein said nanocrystalline particles
are amorphous and have an average crystallite size of less than 2
nm.
24. The method of claim 14, wherein said tobacco product comprises
between about 0.001% to about 2% by weight of said nanocrystalline
particles based upon the weight of the entire tobacco product.
25. The method of claim 14, including the step of combusting a
portion of said tobacco product containing said tobacco thereby
generating tobacco smoke and one or more undesirable compounds.
26. The method of claim 25, said nanocrystalline particles sorbing
at least one of said one or more undesirable compounds contained in
said tobacco smoke.
27. The method of claim 26, said one or more undesirable compounds
being selected from the group consisting of carbon monoxide,
hydrogen cyanide, nitrogen oxides, formaldehyde, acrolein, benzene,
N-nitrosamines, nicotine, phenol, and polyaromatic hydrocarbons
(PAHs).
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/044,758, filed Apr. 14, 2009, which is
incorporated by reference in its entirely.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is generally directed toward abatement
of hazardous, or otherwise undesired compounds contained in tobacco
smoke through neutralization, adsorption, and absorption by the
incorporation of nanocrystalline particles into tobacco
products.
[0004] 2. Description of the Prior Art
[0005] The hazards of tobacco smoke to both the smoker and to
others in the vicinity of tobacco smoke (i.e., secondhand smoke)
are well documented. According to the National Toxicology Program,
tobacco smoke, especially that produced by cigarettes and cigars,
contains at least 250 poisonous gases, chemicals, and metals
including hydrogen cyanide, carbon monoxide, butane, ammonia,
toluene, arsenic, lead, chromium, cadmium, and polonium-210 (highly
radioactive carcinogen), nitrogen oxides, formaldehyde, acrolien,
benzene, certain N-nitrosamines, nicotine, phenol, polyaromatic
hydrocarbons (PAHs). Eleven of the compounds are classified as
Group 1 carcinogens, the most dangerous.
[0006] Tobacco products, especially cigarettes, can employ
cellulose filters devices to assist with removal of smoke, tar and
other particulate matter prior to being inhaled by the user.
However, these filters do not address or mitigate the inhalation of
or release into the surrounding environment of a good number of
these toxic gases and chemicals. Further, traditionally unfiltered
tobacco products such as cigars contain no or relatively little
means to mitigate the release and inhalation of these toxic
materials.
SUMMARY OF THE INVENTION
[0007] In one embodiment according to the present invention there
is provided a tobacco product comprising nanocrystalline particles
and tobacco. Particularly, the tobacco product may be a cigarette
or cigar wherein the nanocrystalline particles are contained within
the product's paper wrapping, incorporated into, mixed, and/or
directly intermingled with the tobacco, or included within a
fibrous filter that forms a part of the tobacco product. In certain
embodiments, the tobacco product comprises between about 0.001% to
about 2% by weight of the nanocrystalline particles based upon the
weight of the entire tobacco product.
[0008] Exemplary nanocrystalline particles for use with certain
embodiments according to the present invention include those
selected from the group consisting of the oxides, hydroxides,
halides, carbonates, nitrates, sulfates, and phosphates of metals,
metalloids, and combinations thereof. In one embodiment, the
exemplary nanocrystalline particles have an average crystallite
size of between about 2 to about 25 nm. In another embodiment, the
nanocrystalline particles may be amorphous and have an average
crystallite size of less than 2 nm. In still other embodiments, the
nanocrystalline particles have an average surface area of at least
20 m.sup.2/g.
[0009] In another embodiment according to the present invention,
there is provided a method of reducing the level of reducing the
level of undesirable components in tobacco smoke from a tobacco
product comprising the step of incorporating a quantity of
nanocrystalline particles into the tobacco product. The tobacco
product may be constructed according to any of the embodiments
described herein, and likewise, the nanocrystalline particles used
with the tobacco product may be any of those nanocrystalline
particles described herein. At least a portion of the tobacco
product is combusted and thereby generating tobacco smoke
(including carbonaceous smoke particulates) and one or more
undesirable compounds. The nanocrystalline particles contained
within the tobacco product sorb smoke particulates and/or at least
one of the one or more undesirable compounds contained in said
tobacco smoke thereby preventing those materials from being taken
in by the smoker or contaminating the surrounding environment.
[0010] In addition to the benefits to the smoker and those in the
immediate vicinity of the smoker, embodiments according to the
present invention also reduce the levels of third-hand smoke
contaminants deposited on surfaces exposed to tobacco smoke.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of a cigarette made in
accordance with one embodiment of the present invention wherein the
cigarette paper is coated with or has incorporated therein a
quantity of nanocrystalline particles;
[0012] FIG. 2 is a cross-sectional view of a cigarette made in
accordance with another embodiment of the present invention wherein
a quantity of nanocrystalline particles are incorporated into or
mixed with the tobacco;
[0013] FIG. 3 is a perspective view of a cigarette made in
accordance with yet another embodiment of the present invention
with the filter portion of the cigarette partially sections, the
filter portion having incorporated therein a quantity of
nanocrystalline particles;
[0014] FIG. 4 is a chart depicting air filtration removal
capacities for various sorbents and hydrogen chloride agent under
dry conditions and 35% relative humidity conditions; and
[0015] FIG. 5 is a chart depicting air filtration removal
capacities for various sorbents and acetaldehyde agent under dry
and 50% relative humidity conditions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] The main undesirable components of tobacco (especially
cigarette and cigar) smoke are inorganic compounds such as hydrogen
cyanide, carbon monoxide, and nitrogen oxide; aldehydes such as
formaldehyde, acetaldehyde, butyraldehyde, crotonaldehyde,
propionaldehyde, acrolien; ketones such as acetone and MEK;
nitrogen compounds such as ammonia, acrylonitrile, pyridine,
N-nitrosamines, and acrylamide; organic compounds such as
polyaromatic hydrocarbons (PAHs), styrene, 1,3-butadiene, benzene,
isopropene, toluene, phenol, fluorene, ethylene oxide, propylene
oxide, and butane; and particulate phase materials such as arsenic,
lead, chromium, cadmium, polonium-210 (highly radioactive
carcinogen), benzo-[a]-pyrene, NNN(N'-nitrosonornicotine),
NNK(4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone), naphthalene,
4-aminobiphenyl, 2-aminonapthalene, and quinoline. The present
invention provides a tobacco product that is capable of reducing or
eliminating the release of one or more undesirable compounds
generated by the combustion of tobacco, and methods of reducing
carrying out this reduction or elimination of undesirable
compounds.
[0017] One embodiment of the present invention comprises the use of
nanocrystalline particles that are capable of adsorbing one or more
undesirable compounds released by burning tobacco. As used herein,
a "nanocrystalline particle" means a high surface area particle
having an average surface area of at least 20 m.sup.2/g and an
average crystallite size of between 2 to 25 nanometers. If the
nanocrystalline material is amorphous, the average crystallite size
can be below 2 nm. The particle itself need not necessarily have
these dimensions, but can present a much larger particle size.
Rather it is the crystals that make up the particle that are
nano-sized. In certain embodiments, the nanocrystalline particles
exhibit an surface area of between about 100 to about 800 nm, or
between about 300 to 700 nm. Nanocrystalline particles are prepared
by conventional means or via an aerogel process described in U.S.
Pat. No. 6,087,294 and Utampanya et al., (Chem. Mater. 3:175-181
[1991]) both incorporated herein by reference.
[0018] Exemplary nanocrystalline materials include oxides,
hydroxides, halides, carbonates, and phosphates of metals,
metalloids, and combinations thereof. In certain embodiments, the
nanocrystalline particles comprise a member selected from the group
consisting of the halides, carbonates, phosphates, oxides, or
hydroxides of alkaline earth metals (e.g., MgO, CaO), alkali
metals, transition metals (e.g. ZnO, TiO.sub.2), and lanthanide
metals, and metalloids (e.g., silicon oxides). The materials may be
in the form of a singular component or a multi-component mixture,
in the form of a powder, embedded particles in or supported on a
media (i.e., paper, Filter, or other components of cigarettes) or
in granular or otherwise aggregated form. Exemplary metal oxides
and metal hydroxides include MgO, CeO.sub.2, CaO, TiO.sub.2,
ZrO.sub.2, FeO, V.sub.2O.sub.3, V.sub.2O, Mn.sub.2O.sub.3,
Fe.sub.2O.sub.3, NiO, Fe.sub.3O.sub.4, CuO, Al.sub.2O.sub.3, ZnO,
SiO.sub.2, Ag.sub.2O, SrO, BaO, Mg(OH).sub.2, Ca(OH).sub.2,
Al(OH).sub.3, Sr(OH).sub.2, Ba(OH).sub.2, Fe(OH).sub.3,
Cu(OH).sub.3, Ni(OH).sub.2, Co(OH).sub.2, Zn(OH).sub.2, AgOH, AlOOH
(alumina oxyhydroxide) and mixtures thereof, obtained from
NanoScale Corporation, Manhattan, Kans., some of which under the
name NanoActive.RTM.. The nanocrystalline particles may also
comprise more than one metal oxide or metal hydroxide species
co-solidified together (as opposed to being coated one over
another). For example, the nanocrystalline particles may comprise
MgO/TiO.sub.2/Al.sub.2O.sub.3 or any combination of the above-noted
metal oxides and metal hydroxides.
[0019] The nanocrystalline particle might be also utilized in a
combination with activated carbon, as a simple physical mixture,
coating of nanocrystalline particles onto activated carbon, coating
of activated carbon onto nanocrystalline particles, nanocrystalline
particles embedded into activated carbon, or any combination
thereof.
[0020] The particles may also comprise one or more reactive species
stabilized on the surface of the nanoparticle. Exemplary reactive
species include halogen atoms, Group IA atoms, and ozone. The
nanocrystalline particle may also be doped with a metal species
such as gold, platinum, ruthenium, rhodium, or palladium to achieve
a catalytic oxidation of certain contaminants. For example, CO
contained in the tobacco smoke may be converted to CO.sub.2 through
such catalytic oxidation.
[0021] The particles may be coated to protect them from the
moisture (i.e., air stable nanoparticles as disclosed in U.S. Pat.
No. 6,860,924 incorporated by reference herein in its entirety),
coated with halogens, metal halides, or with another metal
oxide/hydroxide (see, U.S. Pat. Nos. 6,843,919, 6,653,519,
6,417,423, RE39,098, 6,087,294, 6,057,488, and 5,990,373, all of
which are incorporated by reference in their entireties).
[0022] In case that the air stable nanoparticles are utilized, and
they are distributed evenly through the tobacco product
(particularly a cigar or cigarette), the heat generated would cause
the coating to be removed/burned of exposing a fresh nanoparticle
available for chemical interaction with the hazardous compounds.
Exemplary air stable nanoparticles include those selected from the
group consisting of MgO, SrO, BaO, CaO, TiO.sub.2, ZrO.sub.2, FeO,
V.sub.2O.sub.3, V.sub.2O.sub.5, Mn.sub.2O.sub.3, Fe.sub.2O.sub.3,
NiO, Fe.sub.3O.sub.4, CuO, Al.sub.2O.sub.3, SiO.sub.2, ZnO.sub.2,
Ag.sub.2O, the corresponding hydroxides of the foregoing, and
mixtures thereof at least partially coated with a quantity of a
coating material other than metal oxide coatings. As used herein,
"coated" or "coating" is intended to refer to coatings which only
physically coat the particles, as well as those coatings which
modify or react with the metal oxide surfaces. Preferred coating
materials include those selected from the group consisting of
surfactants, oils, polymers (both synthetic and natural; e.g.,
silicone rubber and cellulose and its derivatives), resins, waxes,
silyls, and mixtures thereof.
[0023] The construction of a tobacco product according to the
present invention begins with the selection of a solid
nanocrystalline particle sorbent material capable of adsorbing
and/or chemically reacting with at least one undesired compound
produced by burning tobacco. The nanocrystalline particle material
is dispersed within the tobacco product (such as in the tobacco
itself, within a filter element, or as a coating on or embedded
within fibers of the wrapping paper). FIG. 1 depicts a cigarette 10
comprising an outer paper wrapping 12 having a quantity of
nanocrystalline particles 14 coated thereupon or dispersed with the
fibers thereof. FIG. 2 shows a cigarette 16 comprising a quantity
of tobacco 18 having nanocrystalline particles dispersed therein
inside of an outer paper wrapping 20. Cigarette 16 also includes a
conventional filter 22. FIG. 3 illustrates yet another cigarette 24
in accordance with the present invention that comprises a filter 26
having a quantity of nanocrystalline particles 28 incorporated
therein. Cigarette 24 likewise comprises a quantity of tobacco 30
within an outer paper wrapping 32. It is also within the scope of
the present invention to provide a cigarette that incorporates two
or all three features shown in the above drawings.
[0024] For example, the cigarette may be constructed with the
nanocrystalline particle-containing paper 12, filter 26, and
tobacco 18.
[0025] The nanocrystalline particles may also be provided as
granular sorbents, sorbents attached to a support, or as a bed of
particles such as a packed column within the tobacco product. The
tobacco may be in the form of relatively intact leaves (such as in
a cigar) or comminuted and/or shredded into fine particulates (such
as in cigarettes). In certain embodiments, the tobacco product
comprises between about 0.001% to about 2% by weight of the
nanocrystalline particles.
[0026] In certain embodiments of the present invention, the
nanocrystalline particles resist reacting with moisture, and other
components found in the environment (i.e., carbon dioxide) for a
duration of up to 18 months (the shelf life of the cigarette). In
other embodiments, the nanocrystalline material is capable of
selectively neutralizing toxic compounds while allowing nicotine to
freely pass on to the user, and without significantly altering the
burn characteristics of the tobacco or altering the tobacco
flavors.
[0027] The temperature range of contacting the nanoparticle sorbent
with the undesired compound inside the cigarette filter ranges from
ambient to 800.degree. C. The time of contact ranges from brief
(fraction of a second) to the life of smoked product, or from less
than a minute to about 20 minutes.
[0028] In addition to adsorption/removal of harmful components, the
present nanocrystalline particles are also capable of destruction
of certain contaminants. The sequence below illustrates the
destruction of aldehydes by carbonyl adsorption on surface cites of
the metal oxide followed by the aldehydic hydrogen
dissociation.
##STR00001##
[0029] The reaction schemes below illustrate the destruction of
ethylene oxide via basic and acidic catalytic pathways.
Base Catalytic Pathway
##STR00002##
[0030] Acid Catalytic Pathway
##STR00003##
[0032] Technical data on the efficacy of hazardous material
sorption is provided in U.S. Pat. No. 7,276,640 and PCT Application
Publication WO 2007/051145, both of which are hereby incorporated
by reference in their entireties.
EXAMPLES
[0033] The following examples set for experimental data regarding
the efficacy of certain nanocrystalline particles in the removal of
certain chemical components of tobacco smoke. These examples are
provided by way of illustration and nothing therein should be
viewed as limiting the scope of the present invention.
Example 1
[0034] In this example, data pertaining to the time for NOx and HCN
to break through a packed column of the indicated sorbent at the
stated moisture level is given below. Tested adsorbents were
granulated with granule size 12-30 mesh. Flow of the gas for
NO.sub.2 was 5.3 slpm through a bed 3 cm in diameter and having a
bed depth of 3.7 cm. Flow of the gas for HCN was 2.0 slpm through a
bed 3 cm in diameter and having a bed depth of 1.0 cm.
TABLE-US-00001 Nitrogen Dioxide (NO.sub.2) 200 ppm Breakthrough
Time (min) Sorbent 25% RH 80% RH Zeolite 13X 102 66 NanoActive
.RTM. CaO Plus.sup.1 238 79 .sup.1Available from NanoScale
Corporation, Manhattan, Kansas (.ltoreq.20 nm crystallite size,
.gtoreq.90 m.sup.2/g)
TABLE-US-00002 Hydrogen Cyanide (HCN) 50 ppm Sorbent Breakthrough
Time NanoActive .RTM. ZnO.sup.2 Greater than 6 hours
.sup.2Available from NanoScale Corporation, Manhattan, Kansas
(.ltoreq.10 nm crystallite size, .gtoreq.70 m.sup.2/g)
Example 2
[0035] Breakthrough tests were conducted using 870 mg/m.sup.3 (330
ppm) of sulfur dioxide mixed with air. The tests were carried out
at room temperature (19-23.degree. C.). A superficial gas velocity
was 12 ft/min (6 cm/s) and the bed thickness was 10 mm. Tested
adsorbents were granulated with granule size 12-30 mesh (activated
carbons) or 16-35 mesh (nanoparticle formulations).
[0036] The table below compares SO.sub.2 breakthrough times for
NanoActive.RTM. MgO (characterized in Example 3 below) and two
popular activated carbon sorbents. The data strongly favors
NanoActivce.RTM. MgO in that it outperformed both activated carbons
both before and after humidity exposure.
TABLE-US-00003 Breakthrough Time (hr) (measured at 10% of initial
SO.sub.2 concentration) concentration Dry 50% Relative Adsorbent
(mg/m.sup.3) Conditions Humidity BPL carbon 870 0.1 1.5 ASZM-TEDA
carbon 870 0.8 1.5 NanoActive .RTM. MgO 870 4 2
Example 3
[0037] Breakthrough tests with hydrogen chloride were conducted
with an air stream containing 3100 mg/m.sup.3 (2100 ppm) of agent
at room temperature (20-25.degree. C.). A superficial gas velocity
was 12 ft/min (6 cm/s) and the bed thickness was 10 mm. Tested
adsorbents were granulated, with granule size 12-30 mesh (activated
carbons) or 16-35 mesh (nanoparticle formulations). Tests for this
agent were carried out at 35% relative humidity instead of 50%
relative humidity used for other agents. This change was needed to
avoid condensation and corrosion caused by the HCl agent in the
breakthrough apparatus. FIG. 4 presents the hydrogen chloride air
filtration removal capacities (mg/g) for the BPL and ASZM-TEDA
carbons and the following NanoActive.RTM. metal oxides: MgO, MgO
Plus, TiO.sub.2, Al.sub.2O.sub.3, Al.sub.2O.sub.3 Plus, and ZnO,
characterized as follows.
TABLE-US-00004 Surface Area, Sorbent BET (m.sup.2/g) Crystallite
size (nm) NanoActive .RTM. MgO .gtoreq.230 .ltoreq.8 NanoActive
.RTM. MgO Plus .gtoreq.600 .ltoreq.4 NanoActive .RTM. TiO.sub.2
.gtoreq.500 Amorphous NanoActive .RTM. Al.sub.2O.sub.3 .gtoreq.275
Amorphous NanoActive .RTM. Al.sub.2O.sub.3 Plus .gtoreq.550
Amorphous NanoActive .RTM. ZnO .gtoreq.70 .ltoreq.10
[0038] Air filtration performance of activated carbons towards HCl
was outperformed under both dry and humidified conditions. Under
dry conditions, NanoActive.RTM., ZnO outperformed both carbons by
at least 180% (two-sample T-type hypothesis test and a 95%
confidence level). Under humidified conditions, NanoActive.RTM.
Al.sub.2O.sub.3 Plus outperformed activated carbons by at least
332% (two-sample T-type hypothesis test and a 95% confidence level)
and reached an exceptional removal capacity of (1340+/-270)
mg/g.
[0039] The breakthrough tests conducted with hydrogen chloride show
clear advantages of using selected NanoActive.RTM. metal oxide
formulations under dry and humidified conditions In particular,
NanoActive.RTM. Al.sub.2O.sub.3 Plus had greater than four times
the removal capacity of the ASZM-TEDA carbon under humidified
conditions.
Example 4
[0040] Breakthrough tests with acetaldehyde were conducted with an
air stream containing 540 mg/m.sup.3 (300 ppm) of CH.sub.3CHO in
air at room temperature (20-25.degree. C.). A superficial gas
velocity was 12 ft/min (6 cm/s), and the bed thickness was 10 mm.
Tested adsorbents were granulated, with granule size 12-30 mesh
(activated carbons) or 16-35 mesh (nanoparticle formulations). FIG.
5 presents the acetaldehyde air filtration removal capacities for
the BPL and ASZM-TEDA carbons and the following NanoActive.RTM.
metal oxides: MgO, MgO Plus, TiO.sub.2, Al.sub.2O.sub.3, and
Al.sub.2O.sub.3 Plus (previously characterized herein).
[0041] Under dry conditions, all tested metal oxide formulations
outperformed both activated carbons. NanoActive.RTM. MgO Plus,
TiO.sub.2, and Al.sub.2O.sub.3 outperformed both carbons by at
least 208%, as evaluated using the two-sample T-type hypothesis
test and a 95% confidence level. Under humidified conditions,
NanoActive.RTM. MgO outperformed activated carbons by at least 46%
(two-sample T-type hypothesis test and a 95% confidence level).
[0042] The breakthrough tests conducted with the acetaldehyde show
a clear advantage of using selected NanoActive.RTM. metal oxide
formulations under dry and humidified conditions. This is
particularly significant since the removal capacities for this
agent for both activated carbons are relatively low, in the 8-23
mg/g range. Such low capacities make it difficult to use these
sorbents in air filtration systems. Typically larger capacities, at
least 200-300 mg/g and preferably higher, are needed.
Example 5
[0043] In this example, a number of sorbent materials were tested
for efficacy in removing toluene vapor from air under stationary,
dynamic, and static test conditions. Further testing was performed
on selected sorbents for removal of toluene, acetaldehyde, dietheyl
amine, and ethyl mercaptan.
Materials
[0044] Concentrated hydrochloric acid, 28-30% aqueous ammonia,
hexadecyl-trimethylammonium bromide (C16TMABr), tetraethyl
orthosilicate (TEOS), LE-4 polyoxyethylene lauryl ether, aluminum
sulfate (Al.sub.2(SO.sub.4).sub.3.18H.sub.2O), triethoxyoctyl
silane (TES), and phenyl triethoxyoctyl silane (PTES) were
purchased from Sigma-Aldrich, Sodium hydroxide, ethanol
(histological) and toluene (A.C.S. grade) were obtained from
Fisher. Tetrabutyl ammonium hydroxide (TBAOH) was obtained from
Alfa Aesar. Ludox As-40 (40% wt) silica was obtained from Grace
Davison. Zeolite nanocrystalline CBV 400 and CBV 8014 were obtained
from Zeolyst International. Nanocrystalline titanium dioxide
(NanoActive.RTM. TiO.sub.2 from NanoScale Corporation) and
trimetallic oxide (MgO:TiO.sub.2:Al.sub.2O.sub.3 1:2:1) was
synthesized. All chemicals were used as obtained without further
purification.
Sample Synthesis
[0045] PTES hybrid mesoporous silica was synthesized according to
the method reported by Burkett and coworkers. Burkett, S. L., Sims,
S. D., Mann, S. Synthesis of Hybrid Inorganic-Organic Mesoporous
Silica by Co-condensation of Siloxane and Organosiloxane
Precursors, Chem. Commun., 1996, 1367-1368.
[0046] A LE-4 polymer assisted silicate was synthesized following
the method reported by Lee and coworkers. Lee. J. W. Lee, J. W.,
Shim, W. G. S., Suh, S. IL., Moon, II. Adsorption of Chlorinated
Volatile Organic Compounds on MCM-48, J. Chem. Eng. Data, 2003, 48,
381-387.
[0047] An Al-ZSM-5 silicate was synthesized following the method
reported by Grieken and coworkers (van Grieken, R., Sotelo, J. L.,
Menendez, J. M., Melero, J. A. Anomalous Crystallization Mechanism
in the Synthesis of Nanocrystalline ZSM-5, Microporous Mesoporous
Water., 2000, 39, 135-147), except that the preparation was scaled
up to twice its original scale, and TPAOH, in original literature,
was substituted by TBAOH in the same molar ratio, as the former
reagent was no longer carried by the original vender.
Samples Characterization
[0048] The BET (Brunauer-Emmet-Teller method) surface area and XRD
(powder X-ray diffraction) measurements were taken for all seven
samples. BET analysis was performed on a Quantachrome Nova 2200 BET
instrument. Each sample was first out gassed and then cooled to 77
K, followed by exposure to nitrogen. The amount of nitrogen
adsorbed as a single layer was measured. The surface area was
directly calculated from the number of molecules absorbed and the
area occupied by each. XRD were performed on a Shimadzu XRD-6000
instrument. The results are summarized below.
TABLE-US-00005 Sample Sample Name SSA, m.sup.2/g XRD, 2.theta. 1
CBV400 zeolite 590.6 Crystalline: 12, 16, 19, 24, 27, 30, 31, 32,
34 2 CBV8014 zeolite 371.9 Crystalline: 23, 24, 24.5 3 PTES hybrid
786.2 Amorphous mesoporous silica 4 LE-4 assisted silicate 1019
Amorphous 5 Al-ZSM-5 silicate 662.0 Amorphous 6 NanoActive .RTM.
TiO.sub.2 471.5 Amorphous 7 NanoScale trimetallic 533.0 Amorphous
oxide MgO/TiO.sub.2/Al.sub.2O.sub.3
Methods
[0049] a) Stationary Test Method with GC-FID Detection.
[0050] The test setup comprised a 245 ml gas tight glass reactor
equipped with a sample holder inside for placement of the solids.
All tests were performed in undesiccated ambient air. Initial
experimentation showed that toluene liquid completely evaporates in
the reactor within 1 h after injection, and an accurate calibration
is possible within this time frame. For each test, 20 ul of liquid
toluene was injected into the sealed reactor through the septum on
the side arm and after 1 h a gas sample (1 ml) was taken from the
reactor for analysis by GC-FID. The initial GC peak area was noted
as A0. The reactor was then cleaned by air purging, the desired
sorbent sample (0.6 g powder or 35-60 mesh granules) was loaded on
the sample holder and the reactor sealed. Liquid toluene (20 ul,
sorbent:toluene 10:1 w/w) was injected into the reactor without
directly contacting the sorbent. A gas sample (1 ml) was analyzed
by GC-FID after 1 h. The GC peak area was noted as A1. Percentage
toluene removal by the sorbent was calculated using the formula
1-(A1/A0). The instrument used was a GC-FID 5890 series II,
equipped with a 30 m.times.0.32 mm ID.times.0.25 um EC-Wax column.
The temperature of the injector and the detector was 265.degree.
C., the heating program was 60-100.degree. C. (stead at 60.degree.
C. for 10 min, followed by heating rate 5.degree. C./min to
100.degree. C. for 1 min; toluene retention time 4.7 min). Two
replicates were carried out for each test.
[0051] b) Dynamic Test Method with FT-IR Detection.
[0052] The dynamic test condition was designed to mimic an air
filtration test system that is used in solids testing. The FT-IR
instrument (Thermo Electron Corporation) was equipped with a 2.5 L
gas cell. A gas circulation pump was connected to the JR gas cell
by steel tubing, forming sealable circulation pathway. A glass
solid sample cell with filter frit was connected into the
circulation pathway. All tests were performed in dry ambient air.
After cleaning the test system by air purging, toluene (20 ul) was
injected into the sealed IR cell, vaporized by brief spot heating,
and circulated by the pump with simultaneous IR measurements. When
IR spectra intensity stopped fluctuating, integration of the band
region 3160-2834 cm-1 (C--H stretch) was noted as I0. The pump was
then turned off and the desired sorbent (0.16 g, 35-60 mesh
granules) was quickly loaded into the sample cell. The system was
resealed and the pump was turned back on, continuously circulating
toluene contaminated air through the sorbent sample. IR spectra of
toluene in the vapor phase were taken at various time intervals by
an automatic Macro program continuously for 3 hours. Spectra
integration of the band region 3160-2834 cm.sup.-1 at time t was
noted as It. Percentage toluene vapor removal at a certain time t
can be calculated using the formula 1-(It/I0). Two replicates were
carried out for each test.
[0053] c) Static Test Method with GC-FID Detection.
[0054] The key differences between the previously described
stationary test (a) and the static test herein are the quantities
of air and concentrations of toluene the sorbents were exposed to.
In these tests, the sorbents were challenged by exposure to a
larger quantity of air combining very low concentrations of VOCs.
Static tests were performed in a 4 L gas tight plastic container
equipped with septum valves. All tests were performed in
undesiccated ambient air. In each test, the container was cleaned
out by air purging, injected with the desired VOC vapor so a
definite VOC concentration in the container was reached (45 ppm for
toluene, 50 ppm for acetaldehyde, and 100 ppm for both diethyl
amine and ethyl mercaptan) and then allowed to sit for 30 min for
vapor equilibration. (Time dependent control experiments indicated
that 30 min is sufficient for equilibration of all VOCs tested.)
Then a gas sample (2.5 ml) was taken from the container and
analyzed by GC-FID. The GC peak area was noted as P0. The container
was then cleaned out by air purging, a watch glass loaded with
sorbent powder (0.67 g) was put into the container which was
thereafter scaled and injected with the same amount of VOC) vapor,
as mentioned above. Gas samples and GC-FID measurements were taken
after 0.5, 1, 2, 18 and 24 hours. Right before the 0.5 h
measurement, and right after the 18 h and 24 h measurement, the
test chemical (1 ul) was analyzed by GC-FID in a validation and
verification step. The corrected GC peak area obtained at t hour(s)
was noted as Pt. Percentage VOC removal at t hour(s) was calculated
using the formula 1-(Pt/P0). For toluene, the same GC-FID
instrument and analyzing program as described in the stationary
test method were used. For acetaldehyde, diethyl amine and ethyl
mercaptan, injector and detector temperature was 215.degree. C.,
heating program was 70-775.degree. C. (steady at 70.degree. C. for
5 min followed by heating rate 30.degree. C./min to 175.degree. C.,
finally steady at 175.degree. C. for 1.5 min. retention time is 4.4
min for acetaldehyde, 2.6 min for ethyl mercaptan and 3.9 min for
diethyl amine). Two replicates were carried out for each test.
Results and Discussion
[0055] The surface areas of the seven samples can be divided into
four major groups: 300-500 m.sup.2/g (Samples 2 and 6), 500-700
m.sup.2/g (Samples 1, 5, and 7), 700-800 m.sup.2/g (Sample 3) and
>1000 m.sup.2/g (Sample 4). Sample 2 has the lowest surface area
while Sample 4 has the highest.
[0056] a) Stationary Test.
[0057] Stationary test results with sorbent:toluene (w/w) 10:1 are
summarized below.
TABLE-US-00006 Sample 1 2 3 4 5 6 7 1 h Removal, % 96.8 .+-. 0.2
57.6 .+-. 0.9 75.5 .+-. 0.5 73.4 .+-. 3.4 72.0 .+-. 0 86.7 .+-. 0
76.4 .+-. 0.8
[0058] As seen from the above results, Sample 1 performed the best,
in second place was Sample 6, the third place was shared by Samples
3, 4, 5 and 7, with Sample 2 as the least effective. The sorbents'
performance ranking does not correlate directly with their surface
area ranking except for Sample 2. This suggests that surface area
is not the only factor that determines a sorbent's performance.
After the stationary tests, Samples 1, 6, and 7 were recovered from
the reactor and presence of toluene on them was confirmed by
DRIFTS-IR (data not shown).
[0059] b) FT-IR Dynamic Test
[0060] FT-IR dynamic test results with sorbent:toluene (w/w) 10:1
is summarized below.
TABLE-US-00007 Sample 1 2 3 4 5 6 7 3 h Removal, % 99.4 .+-. 0.1
76.4 .+-. 0.2 49.8 .+-. 0.8 65.8 .+-. 0.5 67.4 .+-. 1.0 77.7 .+-.
0.2 82.2 .+-. 0.1
[0061] In this test, Sample 1 still performed the best, with second
place shared by Samples 2, 6 and 7, and third place shared by
Samples 4 and 5, and Sample 3 as the least effective Based on the
performance ranking and the absolute quantities of adsorption,
Samples 2 and 3 showed appreciable difference in stationary and
dynamic tests).
TABLE-US-00008 Sample 1 2 3 4 5 6 7 Ranking in Stationary 1 4 3 3 3
2 3 Test Ranking in 1 2 4 3 3 2 2 Dynamic Test
[0062] To ascertain the effect of test conditions on apparent
sorbent performance ranking, stationary tests were performed on
Samples 2 and 3 as granules (35-60 mesh). The results were similar
to that obtained with powder. This suggests that the physical form
of sorbents (powder or granules) does not have much effect on the
test outcome. The observed differences in performance ranking are
likely due to differences in test environment (ambient humid air
was used for stationary test while dry air for dynamic test).
TABLE-US-00009 1 h Toluene Removal 1 h Toluene Removal Material by
Powder, % by Granules, % Sample 2 57.6 .+-. 0.9 62.0 .+-. 1.0
Sample 3 75.5 .+-. 0.5 80.4 .+-. 2.8
[0063] To study the relationship between toluene concentration and
sorbent performance, dynamic tests were performed with different
amounts of Sample 6 and toluene. The results are summarized
below.
TABLE-US-00010 TiO.sub.2 (mg)/Toluene (ul) 160/20 60/20 60/10
120/10 3 h Removal, % 77.7 .+-. 0.2 38.8 .+-. 0.2 47.8 .+-. 0.7
65.1 .+-. 0.4 Sorbent/Adsorbed 10:0.77 10:1.03 10:0.64 10:0.43
Toluene (w/w) Approximate 10 20 60 60 Equilibration Time, min
[0064] From the above dynamic test results, it is seen that with
higher initial toluene concentration, the adsorption equilibration
was attained faster. Also, the lower the TiO.sub.2/toluene ratio,
the larger the quantity of toluene adsorbed on TiO.sub.2.
[0065] c) Static Test
[0066] The two samples that showed the best performance in the
dynamic test Samples 1 and 7 (CBV 400 and trimetallic oxide), were
selected for low concentration static tests with multiple VOCs. The
results are summarized below.
TABLE-US-00011 VOC % VOC Removal, h (Conc., ppm) 0.5 1 2 18 24
Toluene 65.9 .+-. 3.1 100 .+-. 0 100 .+-. 0 100 .+-. 0 100 .+-. 0
(45) Acetal- 35.8 .+-. 6.7 78 .+-. 1.9 77.3 .+-. 0.5 75 .+-. 5.6
80.6 .+-. 0.2 dehyde (50) Diethyl 57.5 .+-. 0.1 75.5 .+-. 0.5 79.6
.+-. 0.5 67.9 .+-. 0.5 67.6 .+-. 0.1 Amine (100) Ethyl 65.8 .+-.
0.4 87.0 .+-. 0.2 91.4 .+-. 0.1 77.4 .+-. 0.6 80.6 .+-. 3.0
Mercaptan (100) Toluene 82.6 .+-. 0.2 83.8 .+-. 2.8 83.5 .+-. 3.1
75.7 .+-. 0.8 71.2 .+-. 1.2 (45) Acetal- 87.2 .+-. 3.8 96.4 .+-.
1.0 98.3 .+-. 0.1 98.4 .+-. 0.6 100 .+-. 0 dehyde (50) Diethyl 60.6
.+-. 1.6 74.8 .+-. 1.4 85.8 .+-. 0.6 88.6 .+-. 2.0 87.8 .+-. 0.1
Amine (100) Ethyl 75.6 .+-. 0.6 86.9 .+-. 4.3 96.8 .+-. 1.7 80.8
.+-. 2.4 74.9 .+-. 3.4 Mercaptan (100)
[0067] As shown by this set of results, Sample 1 was better at
toluene removal, adsorbing 100% toluene within the first hour,
while Sample 7 was superior for adsorbing acetaldehyde and diethyl
amine. The two samples adsorption capabilities for ethyl mercaptan
were similar.
[0068] In 24 hours, diethyl amine and ethyl mercaptan partially
desorbed from Sample 1, while toluene and ethyl mercaptan partially
desorbed from Sample 7.
[0069] Among all sorbents tested, CBV 400 (zeolite) was the best
for toluene removal from air, regardless of the test conditions
used, while trimetallic oxide is a better universal VOCs sorbent
than CBV 400. It was also found that higher surface area does not
necessarily lead to better performance of a sorbent in VOC
removal.
* * * * *