U.S. patent application number 09/199296 was filed with the patent office on 2002-01-31 for process for modifying the metal ion sorption capacity of a medium and modified medium.
This patent application is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to LUNDQUIST, SUSAN H..
Application Number | 20020011446 09/199296 |
Document ID | / |
Family ID | 22736983 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011446 |
Kind Code |
A1 |
LUNDQUIST, SUSAN H. |
January 31, 2002 |
PROCESS FOR MODIFYING THE METAL ION SORPTION CAPACITY OF A MEDIUM
AND MODIFIED MEDIUM
Abstract
A process for modifying a medium is disclosed that includes
treating a medium having a metal ion sorption capacity with a
solution that includes: A) an agent capable of forming a complex
with metal ions; and B) ions selected from the group consisting of
sodium ions, potassium ions, magnesium ions, and combinations
thereof, to create a medium having an increased capacity to sorb
metal ions relative to the untreated medium.
Inventors: |
LUNDQUIST, SUSAN H.; (WHITE
BEAR TWP, MN) |
Correspondence
Address: |
GREGORY ALLEN ESQ.
MINNESOTA MINING AND MANUFACTURING CO.
PO BOX 33427
ST PAUL
MN
551333427
|
Assignee: |
Minnesota Mining and Manufacturing
Company
|
Family ID: |
22736983 |
Appl. No.: |
09/199296 |
Filed: |
November 24, 1998 |
Current U.S.
Class: |
210/660 |
Current CPC
Class: |
B01J 20/3042 20130101;
B01J 20/3204 20130101; B01J 45/00 20130101; B01J 20/3078 20130101;
C02F 1/28 20130101; C02F 2101/006 20130101; B01J 20/3248 20130101;
B01J 20/28026 20130101; B01J 20/286 20130101; B01J 2220/54
20130101; B01J 20/0211 20130101; B01J 20/3265 20130101; B01J
20/28033 20130101; B01J 20/3007 20130101; B01J 20/3035 20130101;
C02F 1/281 20130101; B01J 49/50 20170101; B01J 2220/62 20130101;
C02F 1/683 20130101; B01J 20/2803 20130101; B01J 2220/58 20130101;
C02F 1/285 20130101; C02F 2101/20 20130101; B01J 20/10 20130101;
B01J 20/3295 20130101; B01J 2220/52 20130101 |
Class at
Publication: |
210/660 |
International
Class: |
B01D 015/00 |
Goverment Interests
[0001] The invention was made with Government support under
Contract DE-AR2 1-96MC-33089 awarded by the Department of Energy.
The Government has certain rights in the invention.
Claims
What is claimed is:
1. A process for modifying a medium comprising: treating a medium
having a metal ion sorption capacity with a solution comprising (a)
an agent capable of forming a complex with metal ions, and (b) ions
selected from the group consisting of sodium ions, potassium ions,
magnesium ions or a combination thereof, to create a medium having
an increased capacity to sorb metal ions relative to said untreated
medium.
2. The process of claim 1, wherein said agent comprises an organic
acid and said ions are sodium ions.
3. The process of claim 1, wherein said agent is citric acid and
ions are sodium ions.
4. The process of claim 1, wherein said solution comprises sodium
azide.
5. The process of claim 1, wherein said solution comprises an
organic acid and sodium hydroxide.
6. The process of claim 1, wherein said solution has a pH of
between about 6 and 10.
7. The process of claim 1, wherein said solution has a pH of
between about 7.5 and 8.5.
8. The process of claim 1, wherein said medium is capable of
sorbing strontium ions.
9. The process of claim 1, wherein said medium is capable of
sorbing mercury ions.
10. The process of claim 1 wherein said medium comprises a membrane
filled with particles.
11. The process of claim 10, wherein said particles are selected
from the group consisting of particles of sodium titanate,
crystalline silico titanate, mixed salts of titanium silicate,
sulfonated styrene divinyl benzene, SAMMS or a combination
thereof.
12. The process of claim 1, wherein said medium comprises sorbed
metal ions.
13. The process of claim 1, further comprising contacting said
treated medium with a liquid comprising metal ions such that said
metal ions sorb onto said medium.
14. The process of claim 13, further comprising treating said
medium comprising sorbed metal ions with an agent capable of
forming a complex with metal ions for a period sufficient to elute
said metal ions.
15. The process of claim 14, wherein said the agent capable of
forming a complex with metal ions comprises a solution comprising
citric acid and sodium hydroxide.
16. The process of claim 13, further comprising treating said
medium comprising sorbed metal ions with a solution comprising an
organic acid and sodium hydroxide for a period sufficient to elute
said metal ions.
17. The process of claim 13, wherein a back pressure produced
during said process remains relatively constant during said
process.
18. The process of claim 1 further comprising providing a medium
comprising sorbed metal ions, prior to treating said medium.
Description
BACKGROUND OF THE INVENTION
[0002] The invention relates to modifying the metal ion sorption
capacity of a medium.
[0003] Water from waste streams, ground water, holding ponds, water
treatment facilities, storage tanks, rivers, and streams can
contain metals such as iron, zinc, cesium, plutonium, strontium,
technetium, uranium, and americium. For environmental compliance,
it is often desirable or necessary to remove these metals from the
water.
[0004] A variety of methods have been developed for removing metals
from the water in waste streams, ground water, holding ponds, water
treatment facilities, storage tanks, rivers, and streams. Some of
these methods include passing the water containing through a medium
that removes the metal. The medium may be an ion exchange medium
that is capable of sorbing the metal ions in the liquid. The medium
is often packed in a column and once the medium is saturated with
metal ions, the medium and/or column is discarded.
[0005] A method for removing metals from the medium involves
eluting the metal ions from the medium with a strong acid followed
by regenerating the medium with a strong base. These methods,
however, do not always perform with the same level of effectiveness
for all metals. For example, ion exchange media used for the
removal of strontium frequently have a relatively low capacity for
strontium due to large excesses of calcium and magnesium, which
compete with the strontium for sites on the medium. Large excesses
of calcium and magnesium relative to strontium are often present in
waste streams and ground water.
[0006] A variety of agents can be used to elute metal ions from an
ion exchange medium. Nitric acid and hydrochloric acid, for
example, are often used to elute strontium from a strontium
absorber. Nitric acid and hydrochloric acid, however, tend to cause
a gradual increase in back pressure in systems in which they are
employed as the eluant and in systems in which the medium is
reconditioned.
SUMMARY OF THE INVENTION
[0007] The invention features a process for modifying a medium to
increase its capacity to sorb (i.e., adsorb, absorb and
combinations thereof) metal ions, as well as processes for
regenerating the metal ion sorption capacity of a medium that has
been exposed to metal ions, as well as the modified media,
itself.
[0008] In one aspect, the invention features a process for
modifying a medium that includes treating a medium having a metal
ion sorption capacity with a solution that includes (a) an agent
capable of forming a complex with metal ions, and (b) ions selected
from the group consisting of sodium ions, potassium ions, magnesium
ions or a combination thereof, to create a medium having an
increased capacity to sorb metal ions relative to the untreated
medium.
[0009] In preferred embodiments, the complexing agent is an organic
acid (e.g., citric acid) and the ions are sodium ions. In some
embodiments, the solution includes sodium azide. In other
embodiments, the solution includes an organic acid and sodium
hydroxide.
[0010] In preferred embodiments, the treating solution has a pH of
between about 6 and 10, more preferably a pH of between about 7.5
and 8.5.
[0011] In one embodiment, the medium is capable of sorbing
strontium ions. In other embodiments the medium is capable of
sorbing mercury ions.
[0012] In another embodiment, the medium includes a membrane filled
with particles, e.g., particles selected from the group consisting
of particles of sodium titanate (i.e., sodium titanate, sodium
nonatitanate, and combinations thereof), crystalline silico
titanate, mixed salts of titanium silicate, sulfonated styrene
divinyl benzene, SAMMS self-assembled monolayers on mesoporous
supports specific for mercury analytes having a formula
SiO.sub.2--CH.sub.2CH.sub.2--SH, and combinations thereof.
[0013] In other embodiments, the medium includes sorbed metal
ions.
[0014] In one embodiment, the process further includes contacting
the treated medium with a liquid that includes metal ions such that
the metal ions sorb onto the medium. The medium that includes
sorbed metal ions can then be treated with an agent capable of
forming a complex with metal ions for a period sufficient to elute
the metal ions. One example of an agent capable of forming a
complex with metal ions is a solution that includes an organic
acid, e.g., citric acid and sodium hydroxide.
[0015] In one aspect, the invention features a process in which the
back pressure produced during the process remains relatively
constant during the process. In one embodiment, the process further
includes providing a medium that includes sorbed metal ions, prior
to treating the medium.
[0016] The process is useful for treating a medium (e.g., a solid
phase ion exchange medium) that has sorbed metal ions (e.g., heavy
metals, rare earth metals, and radioactive elements). The processes
can regenerate (i.e., restore or increase) the metal ion sorption
capacity of articles that have been previously contacted with a
source of metal ions. The process is particularly useful in
regenerating the ion sorption capacity of articles that are used to
remove metal ion contaminates, and to treat aqueous streams from
sources such as ground water, storage tanks, holding ponds, waste
water treatment facilities, and nuclear waste storage tanks.
[0017] The process of the present invention improves the metal ion
sorption capacity of an article relative to its metal ion
adsorption capacity without treatment. In another embodiment, the
process of the invention improves the metal ion sorption capacity
of an article that includes sorbed metal ions. The processes
according to the present invention also permit the maintenance of a
relatively constant back pressure throughout the process.
[0018] Certain preferred processes according to the present
invention are particularly well suited and can be optimized for the
selective removal and recovery of strontium from a medium.
[0019] Other features and advantages of the invention will be
apparent from the following description of the preferred
embodiments thereof, and from the claims.
DETAILED DESCRIPTION
[0020] The process includes treating a medium having a metal ion
adsorption capacity with a solution that includes: A) an agent
capable of forming a complex with at least one metal ion; and B)
ions selected from the group consisting of sodium, potassium,
magnesium and combinations thereof, to increase the capacity of the
medium to sorb metal ions relative to the untreated medium.
[0021] The treating solution is a buffer preferably having a pH in
the range of about 5 to about 11, more preferably a pH in the range
of about 6 to about 10, most preferably a pH in the range of about
7.5 to about 8.5. The treating solution includes a complexing agent
capable of forming a complex with at least one metal ion. Preferred
agents are capable of forming complexes with ions of, e.g., heavy
metals, rare earth metals, actinides, and combinations thereof.
[0022] Examples of useful complexing agents include organic acids
having more than one carboxyl group including citric acid, tartaric
acid, oxalic acid, succinic acid, malonic acid, and
ethylenediaminetetraacetic acid ("EDTA").
[0023] Other useful complexing agents include lactic acid,
sulphosalicylates, acetylacetonante, and azides (e.g., sodium
azide).
[0024] The treating solution also includes ions, e.g., sodium ions,
potassium ions, magnesium ions and combinations thereof. The
treating solution is brought to the desired pH by the addition of
an appropriate amount of buffer adjusting solution, e.g., base,
which also provides the ions. Examples of useful bases include
metal hydroxides including, e.g., sodium hydroxide, potassium
hydroxide, calcium hydroxide, and magnesium hydroxide, and sodium
azide. The sodium azide can function as both the complexing agent
and a source of sodium ions.
[0025] The addition of ions can be used to convert substantially
all of the particles in the medium to a single salt form, e.g., the
sodium form, such that the medium exhibits an increased propensity
to selectively sorb predetermined ions, e.g., cations or anions.
Preferably ions are added to convert substantially all of the
medium to the sodium salt form. Preferably the medium exhibits a
propensity to selectively sorb strontium ions.
[0026] The treating solution is used to treat a medium that is
capable of sorbing metal ions. The medium includes particles
capable of removing ions from fluids through mechanisms such as,
e.g., ion exchange (e.g., solid phase ion exchange), chelation,
covalent bond formation, and sorption (e.g., adsorption, absorption
and combinations thereof). Preferably the medium is capable of
sorbing ions of radioactive particles, metals (e.g., heavy metals,
rare earth metals, alkaline earth metals, and combinations thereof)
and combinations thereof. Useful media sorb ions of metals from
Groups IA, IIA, IB, IIB, IIIB, and VIII of the periodic table.
Preferably the medium is capable of sorbing ions of metals such as,
e.g., cesium strontium, silver, cobalt, chromium, gold, mercury,
uranium, americium, plutonium, copper, iron, technetium, lead,
zinc, and rhenium.
[0027] Typically the medium consists of finely divided, microporous
particles. Preferably the particles have a relatively large area of
active surface and a uniform size distribution. Useful particles
have an average particle size in the range of about 1 .mu.m to
about 100 .mu.m, preferably about 2 .mu.m to about 75 .mu.m, more
preferably about 9 .mu.m to about 18 .mu.m. Suitable particles
include inorganic, organic, and combinations thereof. Preferably
the particles are ionically charged (e.g., cationic and anionic
particles).
[0028] Useful inorganic media include metal titanates, where the
metal is selected form Group IA and Group IIA metals (e.g., sodium
titanate which includes nonatitanate), silicotitanates (e.g.,
crystalline silico titanate, and mixed salts of titanium silicates)
and combinations thereof. Examples of commercially available
inorganic particles include sodium titanates (available from Allied
Signal Corp., Chicago, Ill.), crystalline silico titanates
(available under the trade designation IONSIV from UOP of
Tarrytown, N.Y.), sorbent particles available under the trade
designation ATS from Engelhard Corporation, Iselin, N.J., and high
capacity resins available under the trade designation NALCITE from
Nalco Chemical Co., Naperville, Ill.
[0029] Examples of useful organic media include sulfonated styrene
divinyl benzene resins (commercially available, e.g., under the
trade designation CATEX from Sarasep Corp., Santa Clara, Calif.)),
organic anion sorber (commercially available under the trade
designation ANEX from Serasep), and organic cation sorber
(commercially available under the trade designation DIPHONIX from
Ichrome Industries of Chicago, Ill.).
[0030] Other useful commercially available particles include SAMMS
self-assembled monolayers on mesoporous supports specific for
mercury analytes having a formula SiO.sub.2--CH.sub.2CH.sub.2--SH
(from Batelle Memorial Institute, Pacific Northwest National Labs,
Richland, Wash.), and Clinoptolite.
[0031] The medium can also include derivatized particles. Useful
derivatized particles include polymeric coated oxide particles and
organic moieties covalently bonded to inorganic oxide particles.
Derivatized particles are described, e.g., in U.S. Pat. Nos.
5,393,892 (Krakowiak), 5,334,326 (Bostick), 5,316,679 (Bruening),
5,273,660 (Bruening), and 5,244,856 (Bruening) and incorporated
herein by reference.
[0032] The particles can be enmeshed in a variety of fibrous,
nonwoven webs, which preferably are porous. Examples of such webs
include polymer pulps, fibrillated polytetrafluoroethylene (PTFE),
microfibrous webs, and macrofibrous webs. Examples of particle
filled webs are described in U.S. Pat. Nos. 5,328,758 (Markell et
al.), 5,071,610 (Hagen et al.), 5,082,720 (Hayes), and 3,971,373
(Braun), the disclosures of which are incorporated herein by
reference. Other useful media may include those media described in
U.S. Ser. No. 08/791,205 entitled, "Spiral Wound Extraction
Cartridge," which was filed on Feb. 13, 1997; U.S. Ser. No.
08/918,113 entitled, "Absorbent for Metal Ions and Method for
Making and Using," which was filed on Aug. 27, 1997; and PCT
publication WO96/29146 published Sep. 26, 1996 and incorporated
herein by reference.
[0033] Another useful medium includes sponge-like (i.e., porous)
medium prepared by compacting spray dried particles under low
pressure (e.g., hand pressure) into a confined space and heating
the compacted particles to a temperature of about 130.degree. C.
for about 72 hours results. Such sponge-like media exhibit
excellent separating ability and relatively low back pressure
during use. Useful sponge-like media are described in U.S. Ser. No.
08/960,528 filed on Oct. 31, 1997 and incorporated herein by
reference.
[0034] The medium can be in the form of an article such as, e.g.,
membranes (e.g., particle embedded membranes, and particle filled
membranes), particle filled microfiber webs, particle coated filter
paper, cartridges, columns (e.g., chromatography columns, short
packed columns), disks and sheets.
[0035] The invention will now be described further by way of the
following examples.
[0036] Objects and advantages of this invention are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this invention.
EXAMPLES
Example 1 and Comparative Example A
[0037] Example 1 and Comparative Example A show the Sr ion loading
of a solid phase extraction ("SPE") media disk preconditioned with
a pH 8 buffer solution (Example 1) and a SPE disk that had not been
preconditioned with the pH 8 buffer solution (Comparative Example
A).
[0038] The pH 8 buffer solution was prepared as follows. A 0.23
Molar citric acid solution was prepared by dissolving 48.33 grams
of citric acid monohydrate (obtained from J.T. Baker, Phillipsburg,
N.J.) in a sufficient amount of deionized water to provide 1 liter
of solution. A 0.5 Molar NaOH solution was prepared by dissolving
20 grams of NaOH (obtained from E.M. Science, Gibbstown, N.J.) in a
sufficient amount of deionized water to provide 1 liter of
solution. About 564 grams of the 0.5 M NaOH solution were added to
404 grams of the 0.23 M citric acid solution to provide the pH 8
buffer solution.
[0039] An extraction medium was prepared by first mixing 13.20
grams (dry weight) of aramid fiber pulp (obtained under the trade
designation "KEVLAR IF306" from E.I. Dupont, Inc., Wilmington,
Del.) with 2000 ml of hot water in a 4 liter laboratory Waring
blender at low speed for 30 seconds to form a slurry. About 0.25
gram of a nonionic dispersant (obtained under the trade designation
"TAMOL 850" from Rohm and Haas, Philadelphia, Pa.) was added to the
slurry and blended in at the low speed setting for 30 seconds.
Next, 43.80 grams of sorbent particles (obtained under the trade
designation "ATS" from Engelhard Corporation, Iselin, N.J.),
containing a mixed salt of titanium silicate, were added to the
slurry and blended in at the low speed setting for 30 seconds.
About 7.5 grams latex binder (3.0 grams of styrene-butadiene
(obtained under the trade designation "GOODRITE 1800.times.73" from
B.F. Goodrich Co., Cleveland, Ohio) dissolved in 4.5 grams of
deionized water were added to the slurry and blended in at low
speed for 30 seconds. Next, 25 grams of a 25% aluminum sulfate
aqueous solution (obtained from Aldrich Chemicals of Milwaukee,
Wis.) were added to the slurry and blended at low speed for 30
seconds. About 1.4 gram of a 10% acrylamide modified cationic
copolymer solution, a flocculating agent (obtained under the trade
designation "NALCO 7530" from Nalco Chemical Company, Naperville,
Ill.) were added to the slurry and blended in at low speed for
about 4 seconds.
[0040] A handsheet was prepared by pouring a portion of the
resulting slurry into a sheet mold apparatus (obtained from
Williams Apparatus Co., Watertown N.Y.). The apparatus was equipped
with a 413 square centimeter porous screen having a pore size of 80
mesh (177 micrometers) at the bottom to allow for drainage. The
poured slurry was allowed to drain for 15 seconds. The resulting
wet sheet was pressed for 5 minutes at 620 kPa using in a pneumatic
press (Mead Fluid Dynamics, Chicago, Ill.). The pressed handsheet
was then dried for 120 minutes at 135.degree. C.
[0041] Two 25 mm diameter disks were cut out of the extraction
medium (i.e., the dried handsheet). For each of Example 1 and
Comparative Example A, one of the 25 mm diameter disks were placed
in a stainless steel disk holder (#1209; obtained from Pall/Gelman
Sciences, Ann Arbor, Mich.). The disk holder was attached to the
top of a flask. A pump (Model 7553-80 with a Model 7518-00 pump
head both from (Cole Parmer Instrument Company, Vernon Hills, Ill.)
was used to pump the pH 8 buffer solution through tubing (obtained
under the trade designation "MASTERFLEX PHARMED TUBING #6485-14"
from Cole-Parmer Instrument Company, Vernon Hills, Ill.) from a
bottle to the disk holder assembly. A pressure gauge (obtained
under the trade designation "ASHCROFT PRESSURE GAUGE," (Model
#3NA22422-013 from Dressler Industries, Stratford, Conn.) was in
line between the bottle containing the pH 8 buffer solution and the
disk holder assembly. The buffer solution was pumped through the
extraction medium for 30 minutes at a flow rate of 5 ml per minute.
The flow diameter of the 25 mm disk extraction medium disk was
about 22 mm.
[0042] An analyte matrix solution (also referred to as a "challenge
solution") was prepared by adding (and then mixing) a sufficient
amount of each of various salts (see Table 1, below) to deionized
water to provide the concentration of ions shown in Table 1. The
total volume of the resulting challenge solution was 20 liters. The
pH of the challenge solution was adjusted to 7.5 with 1 N sodium
hydroxide (obtained from Fisher Scientific, Fair Lawn, N.J.).
1TABLE 1 Molarity, ppm in solution moles/liter Salt Manufacturer
54.5 Ca ions 1.36 .times. 10.sup.-3 Ca(NO.sub.3).sub.24 H.sub.2O EM
Science, Gibbstown, NJ 0.074 Cu ions 1.01 .times. 10.sup.-6
Cu(NO.sub.3).sub.22.5 H.sub.2O J. T Baker, Phillipsburg, NJ 1.75 Fe
ions 1.16 .times. 10.sup.-6 Fe(NO.sub.3).sub.39 H.sub.2O J. T Baker
0.0248 Pb ions 3.13 .times. 10.sup.-5 Pb(NO.sub.3).sub.2 Aldrich
Chemical Co., Milwaukee, WI 0.0332 Cr ions 8.11 .times. 10.sup.-4
Cr(NO.sub.3).sub.29H.sub.2O Fisher Scientific, Fair Lawn, NJ 0.399
Zn ions 1.20 .times. 10.sup.-7 Zn(NO.sub.3).sub.2xH.sub.2O
Mallinckrodt Inc, Paris, KY 0.139 Ba ions 6.39 .times. 10.sup.-7
Ba(NO.sub.3).sub.2 Mallinckrodt, Inc, 19.7 Mg ions 3.87 .times.
10.sup.-3 Mg(NO.sub.3).sub.26H.sub.2O Fisher Chemical 89 Na ions
6.10 .times. 10.sup.-6 NaNO.sub.3 J. T. Baker 0.3 Sr ions 3.42
.times. 10.sup.-6 Sr(NO.sub.3).sub.2 Aldrich Chemical Co.
[0043] The analyte matrix solution, which was continually stirred,
was pumped through each of the Example 1 and Comparative Example A
disk holders at a rate of about 5 ml/minute. The solution passed
through the respective disks was collected in a collection bottle.
Six ml sample fractions of the passed solution were taken after 2,
10, 20, 30, 45, 60, 80, 100, 120, 140, 160 and 180 minutes of flow.
Further, sample fractions of the initial and final feed solution
were also taken. Two 6 ml samples were taken from each of the
respective collection bottles. One drop of 1M nitric acid (Fisher
Scientific) was added as a preservative to each sample. The samples
were analyzed for Sr ions using an inductively coupled plasma
analyzer (obtained under the trade designation "PERKIN-ELMER OPTIMA
3000DV" from Perkin Elmer, Norwalk, Conn.) and EPA Test Method
200.7 ("Determination of Metals and Trace Elements In Water And
Wastes By Inductively Coupled Plasma-Atomic Emission-Spectroscopy",
Revision 4.4, EMMC Version, Environmental Monitoring Systems
Laboratory, Office of Research And Development, U.S. Environmental
Protection Agency, 1994), the disclosure of which is incorporated
herein by reference.
[0044] The results and other details are shown in Table 2,
below.
2TABLE 2 Comparative Example A Example 1 Disk weight: 0.61 gram
Disk weight: 0.78 gram % particle in medium: 68.9% % particle in
medium: 68.9% Weight particle in medium: Weight particle in medium:
0.420 gram 0.537 gram Disk thickness: 0.198 cm Disk thickness:
0.213 cm Bed volume @ 22 mm: 0.752 ml Bed volume @ 22 mm: 0.810 ml
Bed Concen- C/Co for Sr Bed Concen- C/Co for Sr volumes tration (Co
= 0.28 volumes tration (Co = 0.29 passed of Sr, ppm ppm) passed of
Sr, ppm ppm) 0 0.01 0.035 0 0.00 0.035 66 0.03 0.107 62 0.00 0.035
132 0.09 0.321 123 0.00 0.035 199 0.11 0.393 185 0.01 0.035 302
0.14 0.500 277 0.05 0.172 402 0.15 0.535 370 0.06 0.207 535 0.17
0.607 493 0.09 0.310 668 0.19 0.679 616 0.10 0.345 793 0.19 0.679
740 0.12 0.414 925 0.20 0.714 863 0.13 0.448 1058 0.20 0.714 986
0.14 0.483 1191 0.21 0.750 1110 0.15 0.517 Capacity @ 50%
breakthrough*: Capacity @ 50% breakthrough 0.0106 g Sr/100 g
particle 0.0344 g Sr/100 g particle *Capacity breakthrough (C/Co
for Sr) at 50% means the concentration of analyte over initial
concentration at 50% bed volume.
[0045] The Example 1 disk maintained a lower back pressure than did
the Comparative Example A disk. The Example 1 disk had a 50% break
through occur at a bed volume of about 1100 ml of challenge
solution.
Example 2 and Comparative Example B
[0046] Example 2 and Comparative Example B show the Hg ion loading
of a solid phase extraction ("SPE") media disk preconditioned with
a pH 8 buffer solution (Example 1) and a SPE disk that had not been
preconditioned with the pH 8 buffer solution (Comparative Example
A).
[0047] Example 2 and Comparative Example B were carried out as
described for Example 1 and Comparative Example B, respectively,
except (a) the sorbent particles were a mercury sorbent (SAMMS
(Self-assembled monolayers on mesoporous supports) obtained from
Pacific Northwest National Laboratory, Richland, Wash.) rather than
the sorbent particles containing a mixed salt of titanium silicate;
(b) the analyte matrix solution was prepared by dissolving a
sufficient amount of mercuric chloride (obtained from salt Fisher
Scientific Company, Fair Lawn, N.J.) in deionized water to provide
a solution containing 100 ppm Hg ions; and (c) the concentration of
Hg ions was analyzed using Method 3112, "Metals by Cold-Vapor
Atomic Absorption Spectrometry", Standard Methods for the
Examination of Water and Wastewater, 19.sup.th edition, 1995, and
an analyzer obtained under the trade designation "LEEMAN LABS PS200
AUTOMATED MERCURY ANALYZER" from Leeman Labs, Hudson, N.H. The
results and other details are shown in Table 3, below.
3TABLE 3 Comparative Example B Example 2 Disk weight 0.34 gram Disk
weight: 0.32 gram % particle in medium: 73.1% % particle in medium:
73.1% Weight particle in medium: Weight particle in medium: 0.249
gram 0.234 gram Disk thickness: 0.072 inch Disk thickness: 0.072
inch 0.0283 cm 0.0283 cm Bed volume @ 22 mm: 0.695 ml Bed volume @
22 mm: 0.695 ml Bed Concen- C/Co for Hg Bed Concen- C/Co for
volumes tration of (Co = 80. volumes tration of Hg (Co = passed Hg,
ppm ppm) passed Hg, ppm 160 ppm) 0 0 0 0 0 0 36 13.64 0.17 37 0 0
72 17.38 0.21 75 0.11 0.0007 108 19.69 0.24 112 2.2 0.0138 144
21.89 0.27 149 5.4 0.0338 180 23.32 0.29 187 9.2 0.0575 216 25.74
0.32 224 20 0.125 433 37.40 0.46 449 37 0.231 649 49.39 0.61 898 54
0.337 866 56.21 0.69 1122 69 0.431 1082 61.38 0.76 1347 72 0.45
1297 64.68 0.80 1459 64 0.40 Capacity @ 50% breakthrough: Capacity
@ 50% breakthrough: 7.67 g Hg/100 g particle 64.87 g Hg/100 g
particle
[0048] The Example 2 disk maintained a lower back pressure than the
Comparative Example B disk.
Examples 3-5 and Comparative Example C
[0049] Examples 3-5 and Comparative Example C showed the Sr ion
loading of a SPE disk preconditioned with a pH 8 buffer solution
neutralized by 0.5 M sodium hydroxide solution (i.e., using the
Example 1 buffer solution) (Example 3), potassium hydroxide
(Example 4), and magnesium hydroxide (Example 5), respectively, and
a SPE disk that had not been preconditioned with a buffer solution
(Comparative Example C).
[0050] Examples 3-5 and Comparative Example C were carried out as
described for Example 1 and Comparative Example C, respectively,
except the respective buffer solutions for Examples 4 and 5 were
prepared as described below.
[0051] For Example 4, a pH 8 buffer solution was prepared as
follows. A 0.23 Molar citric acid solution was prepared by
dissolving 48.33 grams of citric acid monohydrate (obtained from
J.T. Baker, Phillipsburg, N.J.) in a sufficient amount of deionized
water to provide 1 liter of solution. A 0.5 Molar KOH solution was
prepared by dissolving 28.1 grams of KOH (obtained from EM Science,
Gibbstown, N.J.) in a sufficient amount of deionized water to
provide 1 liter of solution. About 637.71 grams of the 0.5 M KOH
solution were added to 400 grams of the 0.23 M citric acid solution
to provide the pH 8 buffer solution.
[0052] For Example 5, a pH 8 buffer solution was prepared as
follows. A 0.23 Molar citric acid solution was prepared by
dissolving 48.33 grams of citric acid monohydrate (obtained from
J.T. Baker, Phillipsburg, N.J.) in a sufficient amount of deionized
water to provide 1 liter of solution. A 0.5 Molar magnesium
hydroxide solution was prepared by dissolving 29.2 grams of
Mg(OH).sub.2 (obtained from Fisher Scientific, Fair Lawn, N.J.) in
a sufficient amount of deionized water to provide 1 liter of
solution. About 329.7 grams of the 0.5 M magnesium hydroxide
solution were added to 404.85 grams of the 0.23 M citric acid
solution to provide the pH 8 buffer solution.
[0053] The results and other details are shown in Table 4,
below.
4TABLE 4 Comparative Example C Example 3 Example 4 Example 5 Disk
weight: 0.76 gram Disk weight: 0.78 gram Disk weight: 0.75 gram
Disk weight: 0.73 gram % particle in medium: 68.9% % particle in
medium: 68.9% % particle in medium: 68.9% % particle in medium:
68.9% Weight particle in medium; Weight particle in medium Weight
particle in medium Weight particle in medium 0.524 gram 0.537 gram
0.517gram 0.502 gram Disk thickness: 0.082 inch Disk thickness:
0.084 inch 0.033 Disk thickness: 0.090 inch Disk thickness: 0.078
inch 0.0307 0.0322 cm cm 0.035 cm cm Bed volume @ 22 mm: 0.791 ml
Bed volume @ 22 mm: 0.810 ml Bed volume @ 22 mm: 0.869 ml Bed
volume @ 22 mm: 0.753 ml C/Co for C/Co for C/Co for Bed Conc. Sr
Bed Conc. Sr Bed Conc. Sr Bed Conc. C/Co for volumes of Sr, (Co =
0.35 volumes of Sr, (Co = 0.29 volumes of Sr, (Co = 0.37 Volumes of
Sr, Sr (Co = 0. passed ppm ppm) passed) ppm ppm) passed ppm ppm)
passed ppm ppm) 0 0 0 0 0 0 0 0 0 0 0 0 32 0.1 0.28 30.5 0.01 0.035
25 0.1 0.27 35 0.06 0.16 64 0.12 0.34 61 0.01 0.035 52 0.1 0.27 70
0.09 0.25 128 0.16 0.45 123 0.01 0.035 104 0.12 0.32 138 0.09 0.25
193 0.18 0.51 185 0.01 0.035 160 0.14 0.37 205 0.10 0.28 290 0.21
0.6 277 0.05 0.17 242 0.17 0.46 307 0.12 0.33 386 0.22 0.62 370
0.06 0.20 327 0.19 0.51 411 0.14 0.38 515 0.26 0.74 493 0.09 0.31
442 0.22 0.59 549 0.17 0.47 644 0.27 0.77 616 0.1 0.34 558 0.23
0.62 687 0.20 0.55 773 0.26 0.74 740 0.12 0.41 675 0.24 0.64 825
0.21 0.58 902 0.28 0.80 863 0.13 0.44 791 0.25 0.67 963 0.22 0.61
1031 0.28 0.80 986 0.14 0.48 907 0.26 0.70 1101 0.23 0.63 1160 0.28
0.80 1110 0.15 0.51 1024 0.26 0.70 1240 0.28 0.78 Capacity @ 50%
breakthrough: Capacity @ 50% breakthrough: Capacity @ 50%
breakthrough: Capacity @ 50% breakthrough: 0.00602 g Sr/100 g
particle 0.0344 g Sr/100 g particle 0.0133 g Sr/100 g particle
0.0194 g Sr/100 g particle
Example 6
[0054] Example 6 was carried out as described for Example 1 except
(a) the initial treatment (i.e., the preconditioning) of the SPE
disk with the buffer solution was for 45 minutes at a flow rate of
5 ml/min; and (b) the steps of loading the disk with the analyte
matrix at a flow rate of 5 ml/min. for 60 minutes and then eluting
the disk with the buffer solution at a flow rate of 1.2 ml/min. for
30 minutes, were each successively repeated four times (i.e., four
cycles). The back pressure, as measured with the pressure gauge 5
cm from the disk, at the end of each loading with the analyte
matrix was measured and is reported in Table 7, below.
5 TABLE 7 Cycle Back pressure, kPa 1 24.1 2 34.5 3 68.9 4 124 5
124
Example 7
[0055] Example 7 was carried out as described for Example 1 except
(a) the initial treatment (i.e., the preconditioning) of the SPE
disk with the buffer solution was for 45 minutes at a flow rate of
5 ml/min; and (b) the steps of loading the disk with the analyte
matrix at a flow rate of 5 ml/min. for 60 minutes, eluting the disk
with the buffer solution at a flow rate of 1.2 ml/min. for 30
minutes, and then rinsing the disk with deionized water for 30
minutes at a flow rate of 1.2 ml/min., were each successively
repeated four times (i.e., four cycles). The back pressure, as
measured with the pressure gauge 5 cm from the disk, at the end of
each loading with the analyte matrix was measured and is reported
in Table 8, below.
6 TABLE 8 Cycle Back pressure, kPa 1 10.3 2 6.9 3 10.3 4 10.3 5
20.6
Examples 8 and 9
[0056] Examples 8 and 9 were carried out as described for Example 1
except (a) the buffer solutions and eluants for Examples 8 and 9
were prepared as described below; (b) the sorbent particles were
particles containing sodium nonatitanate (obtained from Allied
Signal, Morristown, N.J.); (c) the initial treatment (i.e., the
preconditioning) of the SPE disk with the buffer solution was for
45 minutes at a flow rate of 5 ml/min; and (d) the steps of loading
the disk with the analyte matrix at a flow rate of 5 ml/min. for 60
minutes and then eluting the disk with the buffer solution at a
flow rate of 1.2 ml/min. for 30 minutes, were each successively
repeated four times (i.e., four cycles).
[0057] For Example 8, a pH 8 buffer solution was prepared as
follows. A 0.23 Molar tartaric acid solution was prepared by
dissolving 34.5 grams of tartaric acid (obtained from Aldrich
Chemical, Milwaukee, Wis.) in a sufficient amount of deionized
water to provide 1 liter of solution. A 0.5 Molar NaOH solution was
prepared by dissolving 20 grams of NaOH (obtained from E.M.
Science, Gibbstown, N.J.) in a sufficient amount of deionized water
to provide 1 liter of solution. About 342.5 grams of the 0.5 M NaOH
solution were added to 366 grams of the 0.23 M tartaric acid
solution to provide the pH 8 buffer solution.
[0058] For Example 9, a pH 8 buffer solution was prepared as
follows. A 0.23 Molar Ethylenediaminetetraacetic acid ("EDTA")
solution was prepared by dissolving 67.21 grams of EDTA (obtained
from Aldrich Chemical Company, Milwaukee, Wis.) in a sufficient
amount of deionized water to provide 1 liter of solution. A 0.5
Molar NaOH solution was prepared by dissolving 20 grams of NaOH
(obtained from E.M. Science, Gibbstown, N.J.) in a sufficient
amount of deionized water to provide 1 liter of solution. About 315
grams of the 0.5 M NaOH solution were added to 400.6 grams of the
0.23 M EDTA solution to provide the pH 8 buffer solution.
[0059] The back pressure, as measured with the pressure gauge 5 cm
from the disk, at the end of each loading with the analyte matrix
was measured and are reported in Table 9, below.
7TABLE 9 Example 8 Example 9 Cycle Back pressure, kPa Back
pressure, kPa 1 6.9 6.9 2 6.9 6.9 3 10.3 6.9 4 -- 10.3
Example 10
[0060] Example 10 was carried out as described for Example 1 except
(a) the buffer solution and eluant was a pH 8.0 organic acid/base
buffer solution prepared as described below; (b) the sorbent
particles were particles containing sodium nonatitanate (obtained
from Allied Signal, Morristown, N.J.); (c) the initial treatment
(i.e., the preconditioning) of the SPE disk with the buffer
solution was for 60 minutes at a flow rate of 5 ml/min; and (d) the
steps of loading the disk with the analyte matrix at a flow rate of
5 ml/min. for 60 minutes and then eluting the disk with the buffer
solution at a flow rate of 1.2 ml/min. for 30 minutes, were each
successively repeated three times (i.e., three cycles).
[0061] The organic acid/base buffer solution was prepared as
follows. A 0.23 Molar sodium azide solution was prepared by
dissolving 14.95 grams of sodium azide (obtained from Aldrich
Chemical Company) in a sufficient amount of deionized water to
provide 1 liter of solution. The solution had a pH of 8.
[0062] The back pressure, as measured with the pressure gauge 5 cm
from the disk, at the end of each loading with the analyte matrix
was measured and are reported in Table 10, below.
8 TABLE 10 Cycle Back pressure, kPa 1 6.9 2 20.6 3 20.6
[0063] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention, and it should be understood
that this invention is not to be unduly limited to the illustrative
embodiments set forth herein.
[0064] Other embodiments are within the claims.
* * * * *