Title of Invention

"A PROCESS FOR REDUCING THE LEVEL OF MERCURY/ARSENIC FROM AN AQUEOUS LIQUID STREAM"

Abstract "A process for reducing the level of mercury/arsenic from an aqueous liquid stream" A process for reducing the level of mercury from an aqueous liquid stream comprising contacting said liquid stream with used Claus catalyst, wherein the used Claus catalyst comprises a sulfur compound bound to the Claus catalyst. Fig.l
Full Text The present invention relates to a process for reducing the level of mercury/arsenic from an aqueous liquid stream.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] This invention relates to the use of chemical sorbents to reduce the levels of contaminants from waste streams. In particular, the invention relates to the use of used alumina, enriched with sulfur, to reduce or eliminate inorganic contaminants, including, but not limited to heavy metals or D-block metals, from waste streams. More particularly, the invention relates to the use of used alumina to reduce the levels of mercury and arsenic from waste streams.
Background of the Invention
[0003] Industrial pollutants such as heavy metals, D-block metals, mercury and arsenic pose significant health-related risks to the public For example, several metal ions and transition metal ions have been associated with asthma symptoms such as activation of mast cells and enhanced allergen-mediated mast cell activation. Walczak-Crzewiecka, et al "Environmentally Relevant Metal and Transition Metal Ions Enhance Fee RI-Mediated Mast Cell Activation,' Em. Health Perspectives 111(5) (May 2003). Because these substances are generated as a by-product of industrial processes, it is important to find
effective means to reduce their release into the environment.
10004] Por example, merciiry emissions from coal-fired utilities,
commercial boilers and solid waste incinerators represent a serious
environmental problem and have been the focus of many regulatory
deliberations. The Clean Air Act Amendments of 1990 (Tit 1H, § 112(b)(l))
require major sources to use maximum available control technology to reduce
mercury emissions. The United Nations has considered binding restrictions on
the use of mercury through its environment program and has announced that it
will begin to assist countries in developing methods for reducing mercury
emissions. Lacey,M., N.Coru«rence Backs Efforts to Curb Mercury
Pollution," NY Times (Feb. 10,2003). At present, coal-fired power plants «mit the
largest source of mercury emissions at 32.7%. Municipal waste incinerators and
non-utility boilers each contribute approximately 18% of mercury emissions.
Medical waste incinerators contribute 10% of mercury emissions.
[0005] Mercury exposure has been associated with neurological and
developmental damage in humans. Developing fetuses and young children are
at particular risk of the harmful effects of mercury exposure, fciareport
prepared for Congress, the Environmental Protection Agency {"EPA") identified
mercury as a particular danger to public health. Among other health-related
concerns, the report identified increased levels of mercury in the blood of women
of chfldbearing age. "Mercury Threat to Children JRismg, Says an Imreleased
EPA Report/ Watt & /., F«b, 20,2003, Al. Mercury contamination is also a
concern for populations exposed to dental practices or dental waste, clinical
chemistry laboratories, pathology laboratories, research laboratories, chlor-alkali
[0006] To address these concerns, the EPA proposed regulations lhat
would require reductions in mercury emissions from coal-fired power plants.
EPA Press Release, December 14,2000. In addition, legislation has been
proposed fiiat would cut mercury emissions by 50% by 2010 and by 70% by 201&
Watt Sf. /., Feb, 20> 2003. However, despite the desire to reduce mercury
emissions, presently there are no commercially available technologies to control
mercury emissions. Id.
[0007] Similarly, exposure to arsenic poses potentially significant health
risks. Arsenic is a natural element; distributed throughout the soil and in many
kinds of rode. Because of its ubiquitous presence, arsenic is found in minerals
and ores that contain metals used for industrial processes. When these metals are
mined or heated in smelters, the arsenic is released into the environment as a fine
dust. Arsenic may also enter the environment from coal-fired power plants and
incinerators because coal and waste products contain some arsenic. Once arsenic
enters the environment it cannot be destroyed.
[0008] Arsenic exposure causes gastrointestinal problems, such as
stomach ache, nausea, vomiting, and diarrhea. Arsenic exposure can also yield
. decreased production of red and white blood cells, skin changes that may result
in skin cancer, and irritated kings. Inorganic arsenic has been linked to several
rypes of cancer and is classified as a Group A, human carciriogerL In high
amounts (above about 60,000 ppb in food or water), arsenic may be fatal.
Because of the serious adverse health effects related to arsenic, in 2001, the EPA
issued regulations limiting the amount of arsenic in drinking water to 10 parts
per billion. 66 Federal Register 6976.
[0009] Similar adverse effects have been associated with other inorganic
contaminants such as cadmium, chromium, lead, and selenium. Cadmium, for
example, is associated with chronic kidney, liver, bone and blood damage. Like
mercury and arsenic, cadmium occurs naturally in metal ores and fossil fuels;
industrial releases of cadmium axe due to waste streams and leaching of landfills.
Another contaminant chromium, Is associated with such long-term effects as
damage to liver/ kidney, circulatory and nerve tissues/ as well as skin irritation.
The level of chromium in drinking water is regulated by the Safe Drinking Water
Act of 1974. ChronUum is released to rneermran^
manufacturing and combustion of natural gas, oft, and coal- Lead is another
contaminant associated with negative health effects, such as brain and nerve
damage in children, behavior and learning problems/ and reproductive
problems. Lead is released to the environment through various industrial
processes.
[0010] Various carbon-based sorbents have been identified for removing
mercury vapor from gas streams. T.R Catey and CF. Richardson, "Assessing
Sorbent Injection Mercury Control Effectiveness in Hue Gas Streams,"
Enoinmmentid Progress 19(3): 167-174 (Fall 2000). For example, Selexsorb® HG
(Alcoa World Alumina, LLQ Pittsburgh, PA) and Mersorb® (Nucon
International, Inc., Columbus, OH) are commercially available carbon-based
mercury sorbents. Recycled tires have also been identified as a source of
activated carbon that could be used for mercury removal. C. Lehmann rt al.,
'Recycling Waste Tires for Air-Quality Control" Jan. 2000. Activated carbon has
many drawbacks for use in large-scale industrial processes, however. In
particular/ commercially available activated carbon is a relatively expensive
sorbent Although transformation of waste tires into activated carbon is an
environmentally friendly means of recycling harmful waste, it is a complicated,
lengthy, energy-intensive and time-consummg process. Additionally/ me yield
activated carbon from waste tires is relatively low.
10011] Thus, there is a need for new technologies to efficiently and costeffectively
reduce the level of inorganic contaminants, such as mercury and
arsenic for example, in industrial emissions.
[0012] Activated alumina is a well-Jcnown sorbent. Industrial
applications for activated alumina include: natural gas processing, dryers and
forming, ethyiene processing, petroleum refining, air separation, catalyst
support hydrogen peroxide manufacturing, and water treatment Alumina has
applications in ceramics, refractories, refining, abrasive materials/ glass, cennents
and powder metallurgy, electrical applications, coatings/ fibers, metallizing, and
gas dehydration.
[0013] As used herein, "used alumina* Is a by-product of a chemical or
industrial process that enriches the alumina with sulfur or sulfur-containing
compounds. A significant source of used alumina is the Oaus process/ which is
used to recover elemental sulfur from hydrogen sulfide in gases. Industrial
applications of the Cktts process Include, without limitation, steel production/
refineries and natural gas refineries. Activated alumina is used as a catalyst in
the Oaus process. As more sulfur is depositedonto the activated altorrina
through the Oaus process, the material loses its catalytic ability and becomes.
"spear1* or "used."
[0014] Used alumina represents a significant source of industrial waste.
Approximately 50,000 to 75,000 tons of used alumina are generated annually.
Regeneration of used alumina/ such as Oaus catalyst is an expensive process,
however. Because it is economically disadvantageous to regenerate the used
alumina, much of the used alumina ends up in landfills. Thus, there also exists
need to recycle used alumina into other useful applications.
SUMMARY OF THE INVENTION
[0015] The inventors have discovered unexpected arid surprising
characteristics of used alumina. In particular, it has been discovered that used
alumina that is enriched with sulfur is a particularly effective sorfaent for
reducing levels of inorganic contaminants from fluid streams. Nonlimiting
examples of contaminants mat can be reduced using used alumina are heavy
metals/ D-block metals, chalcogens, Group 15 metals, mercury, arsenic,
chronrium, cadmium, lead, and selenium.
(0016] In one aspect, the invention provides a process for removing
mercury from waste streams using used alumina. Thus, the invention provides a
useful means of recycling a material that is otherwise considered industrial
waste. Moreover, by employing a recycling process, theinventive process
provides significant cost savings over traditional methods that use commercially
prepared sorbents used to remove pollutants from waste streams. For example,
commercial sorbents Selexsorb® (Alcoa) and Mersrob® (Nucon) cost between
five and seven dollars per pound, whereas the cost of used alumina recovered
from the Qaus process is less than one dollar per pound. In some embodiments,
the sulfur-enriched alumina of the invention is effective at removing both ionic
mercury and elemental mercury from industrial waste streams.
[0017] m one embodiment, the invention provides a process for reducing
the level of an inorganic contaminant from a fluid stream by contacting the fluid
stream with used alumina. In another embodiment, the invention provides a
process for reducing the level of an inorganic contaminant from a fluid stream
including the following steps; (1) flowing the fluid stream through a bed
containing a sorbent that includes used alumina; (2) sorbing, either by adsorption
or absorption, the inorganic contaminant from the fluid stream onto the surface
of the sorbent; and (3) allowing the contaminant-depleted effluent stream to exit
from the outlet of the bed. Nonlimiting examples of inorganic contaminants
include: heavy metals, D-block metals, chalcogens, Group 15 metals, mercury,
arsenic, chromium, cadmium, lead, and selenium. In some embodiments, the
fluid stream is gaseous. In other embodiments, the fluid stream is liquid. In yet
further embodiments, the mercury is ionic or elemental.
£0018] In one embodiment the invention provides a process for reducing
the level of mercury from a fluid stream by contacting the fluid stream with used
alumina. In another embodiment, the invention provides a process for reducing
the level of mercury from a fluid stream including the following steps: (1)
flowing the fluid stream through a bed containing a sorbent (hat includes used
alumina; (2) sorbing mercury from the fluid stream onto the surface of the
sorbent; and (3) allowing the mercury-depleted effluent stream to exit from the
outlet of the bed. In some embodiments*, the fluid stream is gaseous. Gaseous
fluid streams include, without limitation, those as a result of the burning of
bituminous coal or Powder River Basin and lignite coal, hi other embodiments,
the fluid stream is liquid. In yet further embodiments, the mercury is ionic or
elemental.
(00191 In a furtheraspect; &e invention provides a process for removing
arsenic from fluid streams using used alumina. In one embodiment the used
alumina is used Claus catalyst. In another embodiment, the invention provides a
process for reducing the level of arsenic from a fluid stream including the
following steps: (1) flowing the fluid stream through a bed containing a sorbent
that includes used alumina; (2) sorbing arsenic from the fluid stream onto the
surface of the sorbent; and (3) allowing the arsenic-depleted effluent stream to
exit from the outlet of the bed. In some embodiments, the fluid stream is
gaseous. In other embodiments, the fluid stream is liquid. In yet further
embodiments, the arsenic is ionic or elemental.
DESCRIPTION OP THE FIGURES
{00203 Figure 1 is a graphical representation of the thermogravimetric
analysis (TGA) of used alumina sample AA-191, as described in Example fc
[0021] Figure 2 is a graphical representation of the thennogravimetric
analysis (TGA) of used alumina sample AA-199, as described in Example 6.
10022} Figure 3 is a graphical representation of the thennogravimetric
analysis (TGA) of used alumina sample AA-222, as described in Example 6.
[0023] Figure 4 is a graphical representation of the thennogravimetric
analysis (TGA) of used alumina sample AA-246, as described in Example 6.
[0024] Figure 5 is a graphical representation depicting the percent
removal of 10 ppm mercury from 1 g of various sorbents, as described in
Examples.
[0025] Figure 6 is a graphical representation depicting the percent
removal of 10 ppm mercury from 0.1 g of various sorbents, as described in
Example 8.
DETAILED DESCRIPTION
[0026] Thepatent and stientific literature referred to herein establishes
knowledge that is available to those with skill in the art. The issued patents,
applications, and references that are cited herein are hereby incorporated by
reference to the same extent as if each was specifically and individually indicated
to be incorporated by reference In the case of inconsistencies, the present
disclosure will prevail
10027] For purposes of the present invention, the following definitions
will be used:
Mnjtjons
[0028] The term "about" Is used herein to mean approximately, in the
region of, roughly, or around. When the term "about" is used in conjunction -with
a numerical range, it modifies that range by extending the boundaries above and
below the numerical values set forth. In genera^, ihe term "about" is used herein
to modify a numerical value above and below the stated value by a variance of
20%.
[0029] The terms "used alumina'" and "spent alumina" are used
interchangeably herein to refer to alumina mat is a by-product of a. chemical or
industrial process that enriches the alumina with sulfur or sulfur-containing
compounds. In one nonlimitmg example, one form of used alumina isabyproduct
of the Qaus process, which uses activated alumina as a catalyst for
removing or isolating sulfur. "Used alumina" or "spent alumina" is contrasted
with virgin alumina, which has not been subjected to a chemical process. Thus,
used "Turning may contain higher levels of sulfur compared to virgin alumina.
[0090] The terms "sorbent/' "sorb," "sorption" and their variants are
•used herein to refer to a substance that absorbs, adsorbs, or entraps something;
the act of absorbing, adsorbing, or entrapping; or the process of absorbing,
adsorbing, or entrapping. As used herein, these terms are not intended to be
limited to a particular mode of entrapment such as absorptive, adsorpu've or
other phenomena.
[0031] The invention provides processes for reducing the level of
inorganic contaminants in fluid streams (., gaseous or liquid) using used
alumina. Nonlirnitmg examples of contaminants that may be reduced using the
processes of the invention are heavy metals/ D-block (le., transition) metals,
chalcogens, Group 15 metals, mercury, arsenic, chromium, cadmium, lead and
selenium. More particularly, the processes of the invention maybe used to
reduce die level o£ mercury and arsenic in fluid streams.
{0032] Without washing to be bound by a particular theory, the inventors
theorize that the unique bonding characteristics of sulfur make it a particularly
good substance for interacting with a variety of contaminants. Sulfur has the
ability to bond directly to all elements except the noble gases and nitrogen gas or
liquid. Greenwood, N.N. and Eainshaw, A., "Chemistry of the Elements/*
Pergamon Press, (1984) at 782-783. Sulfur also has the ability to act as a ligand
(i.e., an organic moiety off a metal center) and as an electron donor which allows
it to react directly with a metal to form a S-M (metal) bond. The literature
describes ceitaiu complexes which involve a sulfur molecule bonded directly to a
metal center. Many amino acids are deri vitized with a sulfur functionality and
thus can bond with metals or enzymes. For example, hemoglobin utilizes a
sulfur functionality, Therefore, it is believed that used, sulfur-enriched alumina
is an effective sorbent for contaminants that have favorable sulfur-bonding
characteristics.
[0033} In one aspect the invention provides a process for reducing the
level of mercury in fluid streams (e.g., gaseous or liquid) using used alumina.
Applications of the invention in liquid systems include, without limitation,
instrument manufacturing, gold mining, fluorescent lamp manufacturing and
recycling, dental wastewater, color-alkali process, water purification, coal-fired
utility scrubber washers and aqueous streams. Applications of the invention in
gaseous systems include, without limitation, coal-fired power plants, natural gas/
hydrogen, and air purification.
[0034] In some embodiments, at least about 50% of the contaminant is
removed from the fluid stream. In other embodiments,, at least about 75% of the
contaminant is removed from the fluid stream. In still other embodiments/ at
least about 90% of the contaminant is removed from the fluid stream.
10035] In some embodiments, at least about 50% of mercury is removed
from the fluid stream. In other embodiments, at least about 75% of mercury is
removed from the fluid stream. In still other embodiments, at least about 90% of
mercury is removed from the fluid stream.
{0036} In another aspect the invention provides a process for reducing
the kvd of arsenic from a fluid stream using used alumina, fin one embodiment,
the used alumina is used Claus catalyst. In one embodiment, at least about 50%
of arsenic is removed from the fluid stream. In another embodiment, at least
about 75% of arsenic is removed from the fluid stream. In still another
embodiment, at least about 90% of arsenic is removed from the fluid stream. In
other embodiments, the arsenic is elemental arsenic. In further embodiments, the
arsenic is ionic arsenic
[0037] The amount of contaminant that is removed is also measured on a
basis of the amount in a given time period. For example, in one nonlimiting
embodiment, between about 10-100% of the contaminant is removed from the
fluid stream within about 0.25-24 hours, hi another embodiment between about
10-100% of the contaminant is removed within about 1.5-2.5 hours. In still
another embodiment, about 10-100% of the contaminant is removed within about
0.25-1.5 hours. In a further embodiment, about 10-100% of the contaminant is
removed within about 1-24 hours, In other embodiments/ about 95% of the
contaminant is removed within about 1-24 hours. In another embodiment, about
60% of the contaminant is removed within about 1-24 hours. In still another
embodiment, about 25% of the contaminant is removed within about 1-24 hours,
in yet another embodiment^ about 40% of the contaminant is removed within
about 1*24 hours.
[0038] The contaminants that are decreased using the methods of the
invention may be in elemental or ionic form. For example, in one embodiment,
when using the processes of die invention to reduce the levels of mercury in fluid
streams, the mercury is in (lie form of mercuric chloride. In another embodiment,
the mercury is in me form of mercury nitrate. In a further embodiment, the
mercury is in the form of elemental mercury (e.g., oxidation state is Hg°).
Similarly, other contaminants removed by the methods of the invention maybe
in elemental or ionic form.
[00391._ The used alumina sorbent is introduced into the fluid stream as
an aerosol or by aspiration, or on beads, as powders, or support on a membrane
to facilitate removal of inorganic contaminants. In some embodiments/ the
sorbent is configured in a free-floating manner; in other embodiments, the
sorbent is in a packed bed configuration. In still other embodiments, the soifrent
is mixed with other materials in the sorbent bed. Man-limiting examples of such
other materials include: other sorbents, silica or sand, glass wool, or molecular
sieves. The fluid stream cmtaiiung the irtorgaraccontam
the used alumina sorbent to facilitate reduction of the contaminant in the stream.
In some embodiments, contaminant reduction is further facilitated by arraying
the alumina in parallel configuration (Le., the fluid stream is split into a series of
parallel streams, each of which is associated with a sorption zone, each
containing used alumina). In other embodiments, reduction is facilitated by
arraying the alumina in series configuration (iev the fluid stream is passed
through a series of successive sorption zones, each containing used alumina).
[0040] in one aspect, the process for reducing the level of inorganic
contaminants in fluid streams comprises the steps of (a) flowing the fluid stream
through a bed containing a sot bent that contains used alumina; (b) sorbing the
inorganic contaminant from the fluid stream onto the surface of the sorbent; and
(c) allowing the effluent stream to exit from the outlet of the bed. The size and
configuration of the sorbent bed will vary, depending on the specific application.
The appropriate bed system depends on the specific application and is readily
ascertainable by those skilled in the art. For example, the steps for contaminant
removal depend on the configuration of the flow stream/ die temperature within
the flow, and the flow rate.
{0041] In one nonlimiting example/ a fixed bed contactor with an inlet
and outlet is filled with used alumina. Nonlimiting examples of fixed bed
contactors are columns and cartridges. The fluid stream is directed through the
inlet end of the contactor through a piping system or other appropriate system,
readily determinable by persons skilled hi the art. As the fluid stream passes
through the contactor containing the used alumina, the metal contaminant (e.g.,
mercury, arsenic, chromium, cadmium, etc,) is sorbed onto the surface of the
alumina, thereby reducing the level of contaminant present in the fluid stream.
The fluid stream is then allowed to exit the contactor through the outlet as
euent.
I0042J In some embodiments, the effluent stream is captured and
recycled for other purposes or for further processing. In other embodiments,
where contaminants are sufficiently removed from the fluid stream, the effluent
is released to the environment or is recycled for other uses.
I [0043] In addition to bed contactors, other removal systems, well-known
to those of skill in the ait, may be used to reduce the level of inorganic
contaminants from fluid streams. In on 2 embodiment &e used alumina Is
injected directly into the fluid stream. I ^ this method, the used alumina is
1
crushed into finely divided particles ani 1 dropped counter-current to the fluid
stream. In one nonlimiting example/ th> particle size of the used alumina is fine
enough to create an aerosol. In other nc nlimiting examples, the alumina particles
form a mist or a doud. In some embodiments/ the ahxxrrirtais introduced to 1he
fluid stream by injection or aspiration tl rough a cylindrical collar that is placed
in the fluid stream. As the alumina pas ;es through the fluid stream, inorganic
contaminants (e.g., mercury, arsenic; cbj omium, cadmium, etc.) sorb onto the
surface of &e alumina, thereby reducing the level of the contaminant from the
fluid stream that has passed through th
alumina. A capture mechanism is then
sorption zone created by the used
ised to isolate and remove the mercurymembrane
container. Before being load
pulverized to a small particle size. The
containing alumina partides. Capture r lechanisms are well-known to those of
skill in the art In one nonlimiting exam pie, electrostatic partides (ESP) are used
as a capture mechanism.
10044] In another embodiment [the bag-house method is used to reduce
the level ofinorgardc contaminants. Thi s method is Jcnown to those of skill in the
art Briefly/ in mis method, used alumui a is loaded into a bag-house,, a permeable
d into the container; the alumina is
ag-house is placed in the flow of a fluid
stream (e.g., a gaseous stream). As the fl cud passes through the used alumina
contained in the bag-house, inorganic cc ntaminants contained in the stream are
sorbed by the alumina.
[0045] Jn yet another embodiment, a batch contacting method is used to
decrease the level of inorganic contaminants in fluid streams. In this
embodiment a predetermined amount of used alumina is placed in a volume of
fluid. The fluid-alumina mixtureis allowed to reach equilibrium, at which point
Jio further inorganic contaminant will be removed from the fluid. In some
embodiments, the mixture is agitated to hasten equilibrium. In other
embodiments,, the pH of the solution is adjusted to optimize contaminant
removal. In one nonlirniting example, thepH of the mixture is adjusted to
between about pH 4 and about pH 5.5. In yet further embodiments/ the pH of
the fluid is adjusted by adding nitric acid or an acid of similar acidity. The
period for reaching equilibrium varies, depending on the size of the container/
the capacity of the used alumina, the mass of the used alumina, the concentration
of the contaminant, the amount of sulfur species on the alumina, and the species
and type of contaminant being sorbed. For example, m some embodiments,
when removing mercury from a fluid stream/ the fluid-alumina mixture is
agitated for between about 0.25 hours and about 48 hours. The used alumina is
then separated from the fluid. In one nonlirniting embodiment, the used alumina
is separated using filtration. In another nonlimiting embodiment the used
alumina is separated using gravity filtration. If the contaminant level of the fluid
has not reached an acceptable level/ successive batches are exposed to fhe
alumina, m the manner described above,
[0046] The conditions under which the removal process is operated are
adjusted for optimal reduction of the contaminant of interest. The conditions
selected for optimization/ as well as the range of each condition, will vary
depending on the mode of the process (eg., liquid or gas) and are well within the
knowledge of those skilled in the art Nonlirniting examples of operating
conditions that are adjusted for optimal reduction include: pH, flow rate,
temperature/ residence time/ flow mode/ and amount of sorbent. The skilled
artisan will recognize that each condition can be adjusted individually or in any
combination with other conditions.
0047] In some embodiments, the pH of the fluid stream is acidic, e.%.,
about pH 0-7. In another embodiment the pH of the fluid stream is about pH 2-
t 6. In a
further embodiment the pH of the fluid stream is about pH 2-4. In some
embodiments, the pH of -die-fluid stream isl^asic, e.g., about pH 7-10. In some
embodiments, the pH of the fluid stream is altered to achieve a particular pH
range, while in other embodiments, the pH is "ambient", meaning it is
unadjusted (i.e., the pH of me stream is its pH after me step immediately
preceding the removal step of Ac invention). Methods for adjusting the pH of
Ihe fluid stream are wefl-inowji to those of skill in the art Nonlimiting examples
of such adjustment methods include: addition of base to increase pH or addition
of acid to lower pH. Examples of suitable bases include, without limitation,
NaOH, NHiOH, BazOH, KOH, and Ce(OH)*. Examples of suitable acids include,
without limitation, HQ, HzS(\ HNO* acetic acid, HaPQ* HC1O*, formic acid,
10048] The flow rate of the fluid stream is also adjusted in some
embodiments to optimize the reduction of the contaminants). In one
embodiment the flow rate is about 0.5-1 L/min. In another embodiznent the flow
rate is about 075-135 L/min. In a further embodiment the flow rate is about
1.25-1 .5 L/min. In yet another embodiment the flow rate is about 1 L/min. In a
still further embodiment the flow rate is about 1.4 L/min.
{0049] In some embodiments, the temperature of the fluid stream is
adjusted to optimize reduction of the contaminants), m one embodiment, the
temperature is ambient In another embodiment, the temperature is about 5-
200°C In another embodiment the temperature is aboutS-^C In a further
embodiment the temperature is about 20-50°C In yet another embodiment
temperature is about 50-100°C. In still another embodiment the temperature is
about 100-200°C In yet a further embodiment- the temperature is about 140*C.
10050] In some embodiments, the residence time is adjusted to optimize
reduction of the contaminants)- In some embodiments, the residence time is
about 1 second to about 48 hours. ID other embodiments, the residence time is
about 1 hour to about 24 hours. In further embodiments, the residence time is
about 1 hour to about 12 hours. In still other embodiments, the residence time is
about 1 second to about I hour. In one embodiment, the residence time is about
0.05-1 second. In another embodiment the residence time is about 0,05-
025 second. In a further embodiment the residence time is about 0.25-
0.5 second. In yet another embodiment the residence time is about 0.5-
1.0 second. In dome embodiments/ the residence time varies with the
temperature of the fluid stream. For example, in one noniimiting embodiment
the residence rime is about 0.73 second at about 23°C- In another nonliiiiibng
embodiment the residence time is about 0.17 second at about 140°C.
10051] The Sow mode of the invention is also varied depending on the
conditions of the process. In some embodiments, the How mode is vertical, i.e.,
downflow. In other embodiments, the Bow mode is horizontal
10052] The amount of used alumina added to the sorbent bed is also
varied to optimize the process of the invention. In one embodiment, about 0.1-
100% of the sorbent bed is composed of used alumina. In another embodiment
about 0.1-1% of the bed is composed of used alumina. In a further embodiment
about 1-25% of me bed is composed of used alumina. In yet another
embodiment about 25-50% of the bed is composed of used alumina. In a still
further embodiment about 50-75% of the bed is composed of used alumina. In
another embodiment about 75-100% of the bed is composed of used alumina. In
situations where the sorbent bed is composed of less than about 100% used
alumina,, nonlixniting examples of materials comprising the remaining fraction of
the sorbent bed include other sorbents, silica or sand, glass wool/ and molecular
sieve. Other materials taiown to those of skill in the art are also contemplated by
the invention.
[0053] The used alumina of the invention may be any alumina recycled
from a chemical or industrial process, in which the alumina is enriched with
sulfur, fa one non-limiting example/ the sulfur-enriched used alumina is used (or
recycled) Claus catalyst. In the Glaus process, activated alumina is used as a
catalyst to remove sulfur-containing compounds from Quid streams. Sulfur
compounds react on the alumina surface to produce Sz and water. Oaus
catalysts can fee doped with SiO?, FezOs, NaaO, TiO?, or Group VIB or VH metals.
The alumina is rendered inactive, or "spent," when the alumina becomes
rehy drated, or when the pores of the alumina become sulfated due to oxygen
entermgiihefiystem. At this point, the catalytic ability of the catalyst decreases.
In some embodiments, the sulfur present in the used alumina catalyst is in the
form of SO*, which most likely adheres to the alumina in the form of aluminum
sulfate. In other embodiments, the sulfur is present in the form of sulfites or
sulfbnes. In still more embodiments, elemental sulfur is present as a deposit on
the surface of the alumina.
[0054] In some embodiments/ the used alumina undergoes oneormore
processing steps before being used as a sorbent for inorganic contaminants (e.%.,
before the used alumina is loaded on the bed or into the sorbent zone). The
processing steps expose a larger portion of the surface area of the alumina,
thereby increasing the capacity of the alumina to sorb contaminants. The
processing steps are performed with used alumina (e.g., Clans catalyst) after it
has been enriched with sulfur. The processing steps increase the number of
sorptive sites available on the alumina, thereby increasing its sorptive
characteristics.
10055] In one embodiment the processing step includes crushing the
alumina. Crushing the alumina increases the surface area of the particles,
thereby exposing additional sorptive sites. Larger particle sizes are effective for
removing contaminants from liquid streams/ whereas smaller particle sizes (e,g,f
less man about 600 mesh or less than about 300 mesh) are required to effectively
remove contaminants from gaseous streams. If the particles become too smalt
however/ their sorptive capabilities may be hindered or eliminated due to a
decrease in the framework size of the particle. In one non-limiting example/ the
alumina is crushed to less than about one millimeter in diameter. In another
example, tine alumina is crushed to less Chan about 0.5 millimeter. In yet another
example/ the alumina is crushed to less than about 0.1 millimeter. In still another
example/ the alumina is crushed to less than about 300 mesh. The particles are
crushed using methods well known to those of skill in the art. The appropriate
method for crushing tite used alumina particles is chosen based on the ultimate
particle size desired. Nonlimiting examples of crushing methods include,
without limitation, a ball mill and mortar and pestle
10056] In another embodiment the processing step comprises heating the
alumina. In one nonlimiting example, the sulfur-enriched ahimina is heated to
less than about 600 °C. In another ncodimiting example/ the alumina is heated to
less than about 500 °C Theheatmg step drives off surface moisture, carbon, and
other volatile material fajmtheatamina. The heating step also affects the surface
area of the alumina/ however. For example, the surface area of activated alumina
is between about 250-300 mVg, white the surface area of calcined alumina is
between about 100-125 mz/g. Calcined alumina is achieved by heating alumina to
temperatures greater than about 1200 CC Therefore, the heating step should be
performed at temperatures sufficient to remove moisture and volatile material,
white avoiding conditions that would fcegjn to affect particle size.
10057] Jn another embodiment, the processing step includes heating the
used alumina as described above, followed by crushing the particles, as
described above. In soil another embodiment, used alumina is heated then
crushed prior to being further enriched with sulfur.
{0058} Effective sorption of contaminants is related to the amount of
sulfur species on or in the sorbent. Thus, the abiUty of the sorbent to remove
contaminants from fluid streams is optimized by manipulating the sulrur content
of the used alumina, for example, higher levels of sulfur relate to improved
sorption characteristics for mercury removal. As shown in Examples 6 and 7,
used alumina sample AA-191 (Metal Alloy Reclaimers, Inc. U, Cleveland, Ohio
("Metaloy")), which has a sulfur content of 22.5%, removed 36% of mercury after
one minute. In comparison, sample AA-222, which has an experimentally
determined sulfur content of 1.5%, removed 24% of mercury after one minute. In
contrast, sample AA-191 removed only 58% of arsenic from a test sample
containing 100 ppm areeniq, whereas sample AA-222 removed 95% of arsenic
from a similar sample (Example 8). Therefore, in some embodiments, the sulfur
content of the dumina is in the range of about 1% to about 50%. In one
embodiment, the sulfur content is at feast about 25%. In another embodiment
the sulrur content is at least about 2%. In still another embodiment the sulfur
content is no more than about 25%. In yet another embodiment the sulfur
content is at least about ai%.
[0059] The sulfur content of the used alumina is manipulated by
methods known to those of skill in the art In one nonlimiting example, the
mercury removal process employs used alumina "as is." That is, the sulfur
content of the used alumina is not altered through further processing. In another
embodiment, the desired sulfur content of the alumina is achieved by adding
sulfur (i.e., doping or enriching) to either used or virgin alumina. Doping is
achieved by methods well-known to those skilled in the art. One nonlimiting
example of a doping method includes pretreating the alumina followed by
exposing it to a gas stream consisting of hydrogen and sulfur-containing
compounds. This method indndes heating the alumina with nitrogen or an inert
gas to remove air and dry the alumina. Once prelrealment of the alumina is
achieved, the alumina is exposed to a gas stream that includes hydrogen and
sulfur-containing compounds. Both hydrogen and sulfur must be present to
convert the oxides on the alumina to sulfides. Nonlimiting examples of doping
agents include carbon distdfide (CSz), dimethylsulfide (DMS), dimethyldisulfide
(DMDS) and other organic sulfides,
[0060] hi another embodiment, the sulfur content of the used alumina is
decreased by driving off excess sulfur. Sulfur removal is achieved by methods
known by those with skill in the art. One nonlimiting example of a sulfur
removal process is pre-redaim bum, wherein the used alumina is heated in the
presence of oxygen. Another method for reducing the sulfur content of used
alumina is through dilution/ a process by which used alumina containing higher
levels of sulfur is mixed with used alumina containing lower levels of sulfur.
[0061] The dispersion characteristics of the sulfur on the surface of the
sulfur-impregnated alumina are also correlated with improved contaminant
sorption. For example, the inventors have observed that contaminant sorption is
increased when the sulfur species is evenly distributed on the surface of the
alumina. Without wishing to be limited to a particular theory, the inventors
believe that when the sulfur species is clustered on the surface of the used
alumina/ the surface area available to sorb the contaminant is decreased. Thus,
although there may be a greater mass of sulfur species on the used alumina,
sorptionwiH be decreased because of the lower surface area. NonlimMng
examples of methods to analyze dispersion characteristics are scanning electron
microscopy, Bfunauer Emmett Teller (BET) surface area analysis and porsimetry.
EXAMPLES
Example 1. Removal of Mercury from Liquid (Aqueous) Samples
{0062} The removal of ionic mercuty{fl) using used alumina was
demonstrated using laboratory synthesized aqueous metal-tainted solutions. The
solutions were prepared at two levels of mercury(II): Ippm and 10 ppcu Spent
alumina samples (AA-199, AA-246, AA-222, AA-191, Metaloy) were used as
sorbents for the liquid phase experiments. These sorbents were reclaimed from
Claus catalyst processes. Used alumina was first dried by placing the sorbent in
a drying oven, at 100 °C for approximately four hours. After drying/ seven
samples of sorbent were weighed. The samples were 0.1 g, 0.25 g, 0.25 g (two
samples for precision)/ 0.5 g, 075 g, 1.0 g, and 1.5 g. The sorbent was added to
the simulated waste sample (100 mL) and the contents of each bottle were
manually swirled (1 minute) to assure complete wetting of all of the sorbenl.
Two control samples were also prepared. The first control contained no sorbent.
The second control sample included virgin alumina that did not contain sulfur.
The pH of each bottle was measured and adjusted to approximately pH4.Q to
approximately pH 5.5 with 1M NaOH or 1M HO, as needed. The bottles were
agitated for up to 24 hours, fallowed by filtration and dilution for sample
analysis.
[6063] Approximately 2-3 mL of sample was removed from each bottie
and the sorbent was filtered from the solution. In a reaction vessel, 1 mLof
sample was diluted to a total volume of 10 mL with 2% nitric acid. One drop of
5% potassium permanganate was added and the solution mixed. A three percent
sodium borohydride was introduced into the vessel, resulting in the formation of
mercury vapors and hydrogen gas. Mercury levels in the treated solutions were
determined by cold vapor atomic absorption (CVAA) spectroscopy. The gas and
vapor was passed through an absorption cell positioned in the path of the
spectrophotometfir. A standard curve was prepared using known concentration
solutions. The curve was fit using linear regression analysis. The mercury
concentration of each of the test samples was calculated by comparing the
response obtained from the instrument to the standard curve.
10064] The results are shown in Tables land 2, below. These data are
average results of multiple independent experiments for each alumina sample.
Two experiments were performed for the 1 ppm sample. Four experiments were
performed for the 10 ppm sample. Capacity is the amount of metal on the
sorbent on a per gram of sorbent basis (mg of metaVg of sorbent).
(Table Removed)
{0065] These data confirm that as little asOtlg/mL of used alumina is
effective at removing as much as 10 ppm of mercury .from aqueous waste
samples. Moreover, because the mercury content in the control samples
(containmg no alumina) did not decrease, these experiments demonstrate that the
loss in mercuiy is a result of the sorption phenomenon and not due to
precipitation. The effectiveness in removing mercury from the samples increased
slightly as more sorbent was added, but was still effective at the lower levels. In
addition, the inability of the virgin alumina control samples to decrease the
mercury levels in the samples confirms the sorption is due to the presence of
sulfur on the used alumina.
Example 2. Removal of Mercury from Gas Samples
[8066] In, this prophetic example, used alumina (Claus catalyst) sorbents
will be screened using an on-line mercury analyzer, which allows monitoring of
outlet mercury concentration from the reactor in real time, thereby reducing the
extensive number of tests that need to be performed in order to determine when
equilibrium has been achieved. Because die oxygen present in simulated flue
gas interferes with the on-line analysis, the screening will be performed using
either nitrogen or argon carrier gas. The sorbents will be tested in range of 70
and 150 °C The amount of mercury seabed on the sorbents will be determined
by CVAA spectroscopy, by leaching the mercury off the sorbent.
[00671 After the initial screening tests, additional tests will be conducted
using simulated flue gas, which requires a batch sampling method using
impingers (Ontario Hydro Method, known to those of skill in the art). Three tests
at different contact time periods will be performed, to assure that equilibrium is
obtained. The mercury will be dosed into the system by an apparatus that
diffuses known concentrations of mercury into a system. The apparatus is a
mercury-filled u-shaped tube. A predetermined flow of gas wifl then be bubbled
into the tube to distribute the mercury. The quantity of mercury being dosed into
me system will be calculated based on the known vapor pressure of mercury and
the known flow rate.
Example 3. Removal of Mercury from Gas Samples - Experiment 92
General Procedure
(00683 In this prophetic example, an elemental mercury (Hg°)
permeation tube (3cm, Via Metconics, Inc) is used io steadily provide Hg° vapor
intone system. The HgP is introduced into the system using nitrogen at a flow
rate of about 100 mL mio* as a carrier gas, which is passed over the permeation
tube. The carrier gas flow rate is maintained with ifte use of a mass flow
controller (MFC). Release of Hg° vapor at a rate of 91 ng mixr*, (11 parts per
billion by volume inlet Hg° concentration) is achieved by immersing the
permeation tube in a temperature-controlled water bath (about 55.5 °Q. The
influent Hg° vapor concentration is repeatedly measured with 4% (w/v)
KMnO4/10% (v/v) HfiOt impinger solutions.
(0069] SiimJated flue gas is chc«en from one of two types; bituminous
coal and Powder River Basin (PRB), based on the type of coal that is present
Bituminous coal results in a higher percentage of oxidized mercury, whfle PRB
coal results in higher percentage of elemental mercury. The simulated flue gas of
PRB and lignite coals primarily consists of 3%(v) oxygen (Oz), 12%(v) carbon
dioxide (CCH 7%(v) water (HO), 500 ppm by volume sulfur dioxide fSOz), 200
ppm by volume nitrous oxide (NO), and 11 ppb by volume elemental mercury
(Hg°) balanced with nitrogen (Ni) gas. For PRB,thesimuIated mixture is .
prepared by blending separate streams of gases supplied from pressurized gas
cylinders of 0.98%(v) SCh in Na, 4140 ppm by volume NO in Nb, a mixture of
80%(v) CCh and 20%(v) O%. and Nz gas humidified via a flask containing water
maintained at 47 *C to approximate a 7%(v) water vapor concentration. The flow
rates of all of these gases are separately controlled by individual mass flow
controllers (MFC). The total 1 Lmfcr1 at 23 °C of gas flow is supplied to a fixed-
bed reactor inlet through preheated Teflon lines with a heating tape to prevent
water condensation. Then, the total stream enters the on-line mercury analyzer
and its effluent gas stream is captured by an impinger train to analyze the
mercury contents by a CVAA spectrophotometer.
Blank Experiments
{0070} Blank experiments are carried out to examine the sorption of
mercury vapor on the tubing/ reactor, and blank glass fiber filter. The system is
cleaned with 10%(v/v) nitric acid and de-ionized water before each experiment to
remove residual mercury in the system as described in Section 8.6.2 of the
Ontario Hydro Method (http://iiribHX»nsulting,com/dowTiload/ontaxiohg.pdf).
Analytical
10071] An on-line Hg analyzer is used to obtain breakthrough curves and
to study the dynamic sorption capacity of the tested sorbents. The analyzer is
calibrated using the calibrated Hg° permeation tube and the mercury detection
limit is determined. The analyzer is designed to detect only Hg° vapor in the gas
stream, and cannot detect any oxidized mercury portion. When mercury
sorption tests are conducted in the system, die effluent mercury can be fully or
partially oxidized due to reactions between elemental mercury, a sorbent, and
other simulated flue gas components. Therefore, the oxidized mercury, if
formed, is captured with an impinger containing either
tiis0aydroxymethyl)aminomethane (tris) solution or potassium chloride (KC1)
solution prior to Hg8 detection using an on-line mercury analyzer.
[0072] The tris solution method (Radian Corp.) has been shown to be
effective in capturing only oxidized mercury in other Electric Power Research
Institute (EPRI) studies. Carey, T. R.; Hargrove Jr., O. W.; Richardson, C R;
Chang, R.; Meserole, F. B. Factors Affecting Mercury Control in Utility Flue Gas
Using Activated Carbon. /. Air & Waste Manage. Assoc. 1998,48,1166. The KC1
solution i$ the first impinger set used in the Ontario Hydro Method to determine
oxidized mercury. Other gas components in the simulated flue gases such as
SQz, H0, and HaO are also known to interfere with 253.7-nm ultra violet (UV)
irradiation emitted from a mercury lamp in the on-line mercury analyzer.
Therefore, the gas passing through the tris or KQ solution flows through another
sodium carbonate (NaaCO3) buffer solution to remove SQz and HC1 from the
effluent gas stream. The effluent gas stream goes through an empty impinger
plaosd in an ice l«th as a water trap before HgB is finally detected with the online
mercury instrument Then, the total stream leaving the on-line mercury
analyzer is captured by an Ontario Hydro impinger train to analyze the mercury
contents by the CVAA spectrophotometer.
Fixed-Bed Sorption Experiments
[0073] The used alumina is tested using the on-line mercury analyzer for
monitoring the effluent Hg°, and an Ontario Hydro impinger train under the
simulated flue gas to validate the system performance. The sorbent samples are
mixed in silica diluent (SiOz, Fisher Scientific, fine granules, particle size: 149-420
um) prior to being packed in the reactor. About 20-30 mg of each sorbent in 6 g
of silica is used and the bed material is supported by a fritted quartz disk with a
Teflon o-ring and a glass fiber niter with a nominal 1 |Jm pore diameter in order
to minimize channeling and prevent the escaping sorbent through the bed.
Typical test conditions are summarized in Table 3, below. An additional filter
system with a glass fiber filter with a nominal 0.7 um pore diameter is used at the
outlet of the reactor to capture sorbent particles potentially escaping from the
bed.
(Table Removed)

[0074] During each test the mercury-laden inlet gas bypasses the
sorbent bed and is passed to the analytical system until the desired inlet mercury
concentration is established. Then, the sorption test is initiated by diverting the
gas flow through the sorbent column in downfiow mode to minimize the
potential for fluidization of the bed. All of the tubing and valves in contact with
elemental mercury are constructed from Teflon, which has been demonstrated to
have good chemical resistance and inertness toward elemental mercury. The
sorbent bed and filter system is placed in a temperature-controllable convection
oven, which can maintain die system temperature within 0.5 °C A Teflon coated
thermocouple is installed in the fixed-bed reactor to control the gas temperature
at the inlet of the sorbent bed.
[00751 When mercury spedation studies are conducted/ an impinger
train employed from the Ontario Hydro Method for collection of mercury
samples is placed on the outlet side of the system. The total gas flow rate is
monitored at die outlet of the impinge? system using a bubble flow meter.
Example 4, Dispersion of Sulfur on the Surface of Used Alumina
[00761 The dispersion characteristics of sulfur on the surface of used
alumina were investigated by scanning electron microscopy (SEM). Each sample
was ground into a powder in an agate motor and pestle and then passed through
a 600 mesh sieve to assure uniform sample size.
10077] SEM analysis was performed on virgin alumina Maxcell 727
(Porocel Adsorbents, Catalysts & Services, Little Rock, Arkansas) and UOP S-201
(UOP LLC, Des Plaines, Illinois) to establish a baseline for comparison with the
sulfur-containing samples. Both materials are pure white powders. The pore
structure of Maxcell 727 was relatively open and exhibited only the alumina
support; no surface species (sulfur) was detected. Compared to the Maxcell
sample, the pore structure of the UOP S-201 was not as open; it also did not
exhibit a surface (sulfur) species.
[0078] SEM analysis was performed on four samples of used alumina,
AA-222, AA-199, AA-246, and AA-191 (Metaloy). AA-222 exhibited tight pore
structure, similar to UOP S-^tt. Small aggregates were observed on the surface
of the support Elemental Diffraction Analysis (EDAX) indicated the presence of
approximately >2% sulfur, based on counts per second. The EDAX data suggests
that the aggregates observed in the SEM are sulfur species. AA-199 indicated the
presence of approximately 2% sulfur, based on EDAX analysis. The SEM also
showed the presence of sulfur aggregates. AA-246 exhibited tight pore structure,
similar to UOP S-201. The sulfur species was present at approximately >1%
(EDAX). The SEM showed fewer aggregates on the surface of the alumina
compared to the other samples. AA-246 also exhibited tight pore structure,
similar to UOP S-201, Hie sulfur species was present at approximately 20%
(EDAX). The SEM showed a uniform dispersion of sulfur aggregates in a higher
concentration than the other samples. The distribution of the sulfur in each of the
Metaloy samples was ubiquitous and evenly distributed on the surface of the
alumina, regardless of the total amount of sulfur present. The data are
summarized in Table 3.
(Table Removed)

— 1 _r5« J I bvenly dispersed aggregates
[0079) These data demonstrate that, while the quantity of sulfur may
vary from sample to sample, the sulfur deposited on the used alumina is uniform
in size and distribution.
Example 5, X-Ray Powder Diffraction Analysis of Alumina
[0080] X-ray powderdiffraction (XRD) was used to identify the type of
surface species present in used alumina samples from the Qaus process. The
technique also determined if any phase changes of me alumina support occurred
as a result of the Claus process,
[00811 Analysis was performed on powdered samples and mounted
using the accepted standard analysis technique. The sample is crashed to a
consistent size, no passing through a mesh is needed. The crushed powder is
then introduced into a stainless steel holder using a backfilling technique. The
backfilling allows the sample to be pressed into the sample holder which enables
the sample to remain in place. The backfilling technique also increases the
random order of the packing of the sample. The lamp sources of Cu-oc and the
scanning 26 region was from 10-70 degrees.
[0082] Analysis of UOP S-201 and Maxeett 727 did not indicate the
presence of a surface specks. The spectra were representative of the spectra for
alumina oxide (AhOa). The form was Y-ahunina, with a small portion of o>
alumina. The two spectra were nearly identical, indicating the same phase of
alumina/ with major peaks at 28,38,43,50, and 68 26 values.
[0083] Two samples of amorphous activated carbon used for mercury
sorption were also analyzed as a comparison. Mersorb® (Nucon) and Selexsorb®
(Alcoa) where each showed a sharp spike at 27 29, which appeared to be
crystalline and indicates the possible presence of a sulfide (£?•) species.
[00841 Four samples of used alumina were analyzed (AA-199, AA-222,
AA-246, and AA-191, Metaloy). The spectra confirmed that these samples shared
the same phase-support as the two virgin materials, UOP S-201 and Maxcell 727.
These data confirm that no phase change of the alumina occurs due to the Glaus
reaction and also that the sulfur is not incorporated into the alumina framework.
[0085] An increase in intensity was observed among the used alumina
samples, which is attributed to the presence of sulfur on the surface of the
alumina. The spectra for all four samples were comparable, showing peaks at 28,
38,43,58 and 68 28. The particular sulfur species could only be determined for
AA-191, which had significantly more sulfur content man the other samples. The
relatively small amount of sulfur present in the other samples prohibited
determination of sulfur species. Sample AA-191 showed additional spikes at 23,
26,28 26, which, were further analyzed and determined to be the S& form of
sulfur.
Example 6. Thennogravimetric Analysis of Used Alumina
Thennogravimetrlc analysis (TGA) was also used to determine
the quantity of sulfur species on used alumina from the Claus process. In the
experiments, about 6-9 mg of sample was crushed into a powder and exposed to
an oxygen environment. The sample was then heated at a rate of 20 "C per
minute until the temperature reached 800 °C The samples were analyzed twice,
once without pretreabnent, and a second time with pxetreatment which included
heating for 24 hours at 110 °C
[0067] As a control, two virgin materials (UOP S-201 and Maxcell 727)
were analyzed. Two samples of activated carbon sorbent, Mersorb® and
Selexsorb®, were also included for comparison.
[0088] The TGA profiles of used alumina samples AA-199 and AA-222
(Figures 2 and 3, respectively) were similar to those of the virgin material, which
demonstrate a gradual decrease in mass over the temperature range. These data
confirm a lower quantity of sulfur present in these materials compared to AA-246
and AA-191 (Figures 4 and 1, respectively), whose profiles were qualitatively
different from the other samples. The TGA spectrum for AA-191 showed a sharp
decrease in mass starting at approximately 250 °C and ending at approximately
325 °C. Sample AA-246 also showed a decrease in this range, although the
change was not as sharp as observed for AA-191.
[00891 The low initial temperature loss (-250 °Q demonstrates that the
sulfur species is predominately physically soxbed to the surface of the alumina,
most likely via Van derWaals and/or London Dispersion Forces. Chemical
Bonding; of the sulfur to the alumina would result in higher initial temperature
Joss (-300 °Q.
. Example 7. Determination of Sulfur Content in Used Alumina Samples by
Elemental Analysis
[0090] Elemental analysis was performed on the used alumina samples,
virgin material and activated carbon, to determine percent sulfur content. The
calculations used in the analysis were adjusted because the system did not afford
complete combustion. First it was assumed that the total mass lost was the
entire mass of the organics present on the sample (t.e.f eliminating the sulfur
present). Second, it was assumed that the only organic moiety lost was sulfur,
not carbon, hydrogen or oxygen. Because mere was no coke formation on the
used Qatis catalysts, and the TGA analysis did not reveal the presence of other
organic substances, this assumption was valid.
[00911 In the experiment, a known quantity of sample was introduced
into the sample pan (weighing apparatus) on a section of aluminum foil After
weighing, {he foil was crimped to encase the sample. The foil-encased sample
was then introduced into the heating chamber. The sample was heated to a
temperature of 800 °C to insure complete combustion. The final weight was alsa
measured and die amount lost is the quantity which was lost Samples were
analyzed on a Perkm-Elmer Analyst 1100 Series. The data are provided in
(Table Removed)

[0092] These data confirm that sample AA-191 has the highest sulfur
content of the used alumina samples. These data also confirm that the other used
alumina samples contain detectable quantities of sulfur.
Examples. Sorption Experimentation
10093) Sorpfa'on experiments were performed to determine the kinetics
and capacity for mercury removal of the used alumina samples. Two used
alumina samples, AA-191 and AA-222 were evaluated. Virgin alumina (Maxcell
and UOP S-201) was analyzed as a control The ability of the used alumina
samples to remove mercury was compared to the carbonaceous material,
Mersorb and Selexsorb. A system control comprising a known concentration of
mercury in water was also analyzed. This sample was used to ensure that the
disappearance of mercury was not attributed to precipitation. There was no
decrease in mercury concentration in these samples. Thus, the removal of
mercury is not attributed to precipitation.
[0094] The samples were exposed to a laboratory prepared solution
containing 10 ppm mercury(H). The experiments were performed as described
above, Example 1. In one experiment, 0.1 g of sorbent was used. In a second
experiment, 1.0 g of sorbent were used. The sorbent material was powdered to
allow for maximum surface area. The reaction was allowed to proceed for a
period of time up to twenty-four hours, with samples taken at predetermined
times to determine the reaction kinetics. During the reaction, the samples were
shaken horizontally. The data are shown below in Table 6 and Figures 5 and 6.
(Table Removed)

[0095] These data confirm the effective removal of mercury from
aqueous samples using used alumina as a sorbent. These data also suggest mat
the kinetics of removal and the total capacity of the soibent for removal increases
as the sulfur content increases in the material. The used alumina sorbent used for
this experiment, A-191 and A-2Z2 contain approximately 20% and 2% sulfur,
respectively. Mercury removal for the used alumina sorbent is comparable to the
commercially available carbonaceous sorbents.
Example 9. Removal of Arsenic using Used Alumina as Soifcent
[0096] The removal erf ionic arsenic(V) using used alumina was
demonstrated using laboratory synmesized aqueous metal-tainted solutions. The
solutions contained 100 ppm and 1000 ppm arsenic(V) (Na-arsenate). Activated
carbon sorbents, Mersoxb and Selexsorb, were included for comparison purposes.
Virgin alumina samples UOP S-201 and Maxcell 727 were included as controls.
[0097] Activated alumina was first dried by placing uae sorbent in drying
oven, at 100 °C, for approximately 4 hours. After drying, 0.2 g of each sorbent
was weighed. The sorbent was added to 0.01 L of metal solution and the
contents of each bottle were manually swirled to assure wetting of all of the
sorbent When the arsenic concentration was 100 ppm, the pH was fixed at pH 7.
When the arsenic concentration was 1000 ppm, the pH of the samples varied
from pH 6.6 to pH 10.1. The botttes were agitated for a period up to 24 hours.
The temperature and final pH of each bottle was recorded before the samples
were filtered and diluted.
[0098] The amount of arsenic remaining in each sample was determined
by inductively coupled plasma (ICP) spectroscopy. Approximately 2-3 mL of
laboratory synthesized aqueous metal-tainted sample were removed from each
bottle and the sorbent was filtered from the solution. In an analytical vessel,
1 mL of sample was diluted to a total volume of 10 mL with 2% nitric acid. The
sample was then introduced to the ICP via a peristaltic pump and delivered as an
aerosol into the plasma source. The instrument; a Peddn-Elmer 3000 ICP, then
scanned a large series of wavelengths to identify which elements were present.
Each element has a specific energy and is assimilated to a fingerprint. A
calibration curve is assembled prior to analysis using four know concentrations
and the point fit by linear regression. The instrument retains mis curve and then
calculates die unknown's concentration using this curve. The results are shown
below in Table 7, below.
(Table Removed)

[0099] These data demonstrate that used alumina is an effective sorbent
for arsenic. These data also suggest that lower levels of sulfur present in the
sorbent result in improved sorption of arsenic
[01001 While the foregoing invention has been described in some detail
for purposes of clarity and understanding, these particular embodiments are to
be considered as illustrative and not restrictive. It will be appreciated by one
skilled in the art from a leading of this disdosure that various changes in form
and detail can be made without departing from the true scope of the invention
and appended claims.










We Claim:
1. A process for reducing the level of mercury from an aqueous liquid stream comprising contacting said liquid stream with used Claus catalyst, wherein the used Claus catalyst comprises a sulfur compound bound to the Claus catalyst.
2. The process of claim 1, wherein the used Claus catalyst has a sulfur concentration of at least about 0.1-25% by weight.
3. A process for reducing the level of mercury from an aqueous liquid stream containing mercury, comprising the steps of (a) flowing the liquid stream through a bed containing a sorbent, wherein the sorbent comprises used Claus catalyst including a sulfur compound bound to the used Claus catalyst; (b) sorbing mercury from the liquid stream onto the surface of the sorbent; and (c) allowing the mercury-depleted effluent stream to exit from the outlet of the bed.
4. The process of claim 3, wherein the used Claus catalyst has a sulfur concentration of at least about 0.1-25% by weight.
5. The process of claim 1 or claim 3, wherein the used Claus catalyst is crushed prior to being loaded on the bed.
6. The process of claim 5, wherein the used Claus catalyst is heated to remove moisture prior to being loaded on the bed.
7. The process of claim 1 or claim 3, wherein at least about 50% of mercury is removed from said liquid stream.
8. The process of claim 1 or claim 3, wherein at least about 75% of mercury is removed from said liquid stream.
9. The process of claim 1 or claim 3, wherein at least about 90% of mercury is removed from said liquid stream.
10. The process of claim 1 or claim 3, wherein the mercury is elemental mercury.
11. The process of claim 1 or claim 3, wherein the mercury is ionic mercury.
12. A process for reducing the level of arsenic from an aqueous liquid stream comprising contacting said liquid stream with used Claus catalyst, wherein the Claus catalyst comprises a sulfur compound bound to the used Claus catalyst.
13. A process for reducing the level of arsenic from an aqueous liquid stream containing arsenic, comprising the steps of (a) flowing the liquid stream through a bed containing a sorbent, wherein the sorbent comprises used Claus catalyst including a sulfur compound bound to the Claus catalyst; (b) sorbing mercury from the liquid stream onto the surface of the sorbent; and (c) allowing the arsenic-depleted effluent stream to exit from the outlet of the bed.

Documents:

2457-DELNP-2006-Abstract-(20-05-2010).pdf

2457-delnp-2006-abstract.pdf

2457-DELNP-2006-Claims-(20-05-2010).pdf

2457-delnp-2006-claims.pdf

2457-DELNP-2006-Correspondence-Others-(20-05-2010).pdf

2457-DELNP-2006-Correspondence-Others-(21-06-2010).pdf

2457-delnp-2006-correspondence-others-1.pdf

2457-delnp-2006-correspondence-others.pdf

2457-DELNP-2006-Description (Complete)-(20-05-2010).pdf

2457-delnp-2006-description (complete).pdf

2457-DELNP-2006-Drawings-(20-05-2010).pdf

2457-delnp-2006-drawings.pdf

2457-DELNP-2006-Form-1-(20-05-2010).pdf

2457-delnp-2006-form-1.pdf

2457-delnp-2006-form-18.pdf

2457-DELNP-2006-Form-2-(20-05-2010).pdf

2457-delnp-2006-form-2.pdf

2457-DELNP-2006-Form-3-(20-05-2010).pdf

2457-delnp-2006-form-3.pdf

2457-delnp-2006-form-5.pdf

2457-DELNP-2006-GPA-(20-05-2010).pdf

2457-delnp-2006-gpa.pdf

2457-delnp-2006-pct-210.pdf

2457-delnp-2006-pct-220.pdf

2457-delnp-2006-pct-237.pdf

2457-delnp-2006-pct-304.pdf

2457-DELNP-2006-Petition 137-(20-05-2010).pdf

2457-DELNP-2006-Petition 138-(20-05-2010).pdf


Patent Number 241710
Indian Patent Application Number 2457/DELNP/2006
PG Journal Number 30/2010
Publication Date 23-Jul-2010
Grant Date 21-Jul-2010
Date of Filing 02-May-2006
Name of Patentee METAL ALLOY RECLAIMERS INC. II
Applicant Address 6563 WILSON MILLS ROAD,#103, CLEVELAND,OH 44143-3409, USA.
Inventors:
# Inventor's Name Inventor's Address
1 CLAUDE E. KENNARD 26850 BERNWOOD ROAD, BEACHWOOD, OH 44122,USA.
2 MICHAEL A. GONZALEZ 352 EAST MILLS AVENUE, WYOMING, OH 45215, USA.
3 DAVID C. SZLAG 3128 LAKE SHORE DRIVE, SAULT STE. MARIE, MI 49783, USA.
PCT International Classification Number B01D 15/00
PCT International Application Number PCT/US2004/036092
PCT International Filing date 2004-10-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/516,108 2003-10-31 U.S.A.