U.S. patent application number 10/743239 was filed with the patent office on 2005-02-10 for method for removal of guanidine compound from aqueous media.
Invention is credited to Ganesan, Balakrishnan, Guggenheim, Thomas Link, Hall, David Bruce, Khouri, Farid Fouad, Littlejohn, Matthew Hal, Nadkarni, Pradeep Jeevaji, Shyadligeri, Ashok Shankrappa, Silva, James Manio.
Application Number | 20050029194 10/743239 |
Document ID | / |
Family ID | 34749209 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050029194 |
Kind Code |
A1 |
Hall, David Bruce ; et
al. |
February 10, 2005 |
Method for removal of guanidine compound from aqueous media
Abstract
Disclosed is a method for removing a neutral or an ionic
guanidine compound from an aqueous media optionally comprising an
alkali metal halide, wherein the method is selected from the group
consisting of (a) adsorption onto a carbonaceous adsorbent, (b)
adsorption onto a clay adsorbent, (c) filtration through a
nanofiltration membrane, and (d) removal of water and
calcination.
Inventors: |
Hall, David Bruce; (Ballston
Lake, NY) ; Guggenheim, Thomas Link; (Mt. Vernon,
IN) ; Silva, James Manio; (Clifton Park, NY) ;
Khouri, Farid Fouad; (Clifton Park, NY) ; Littlejohn,
Matthew Hal; (Green Island, NY) ; Ganesan,
Balakrishnan; (Bangalore, IN) ; Shyadligeri, Ashok
Shankrappa; (Bangalore, IN) ; Nadkarni, Pradeep
Jeevaji; (Bangalore, IN) |
Correspondence
Address: |
General Electric Company
CRD Patent Docket Rm 4A59
Bldg. K-1
P.O. Box 8
Schenectady
NY
12301
US
|
Family ID: |
34749209 |
Appl. No.: |
10/743239 |
Filed: |
December 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60493589 |
Aug 7, 2003 |
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Current U.S.
Class: |
210/650 ;
210/652; 210/660; 210/679 |
Current CPC
Class: |
C07C 277/06 20130101;
C02F 2101/38 20130101; C02F 9/00 20130101; B01D 61/027 20130101;
C02F 1/281 20130101; C02F 1/283 20130101; C07C 279/04 20130101;
C07C 277/06 20130101; C02F 1/44 20130101 |
Class at
Publication: |
210/650 ;
210/652; 210/660; 210/679 |
International
Class: |
B01D 061/00 |
Claims
1. A method for removing a neutral or an ionic guanidine compound
from an aqueous media comprising less than 4 wt. % of an alkali
metal halide, wherein the method is selected from the group
consisting of (a) adsorption onto a carbonaceous adsorbent, (b)
adsorption onto a clay adsorbent, (c) filtration through a
nanofiltration membrane, and (d) removal of water and
calcination.
2. The method of claim 1, wherein the guanidine compound has the
formula 3wherein each of R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is
independently a primary alkyl radical and R.sup.1 is a primary
alkyl or bis(primary alkylene) radical, or at least one of the
R.sup.1-R.sup.2 or R.sup.3-R.sup.4 combinations with the connecting
nitrogen atom forms a heterocyclic radical; and the value of the
parameter n is 1 or 2.
3. The method of claim 1, wherein the guanidine compound has the
formula 4wherein each of R.sup.2, R.sup.3, R.sup.4, R.sup.5 and
R.sup.6 is independently a primary alkyl radical and R.sup.1 a
primary alkyl or bis(primary alkylene) radical, or at least one of
R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 is hydrogen, or at
least one of the R.sup.1-R.sup.2, R.sup.3-R.sup.4 or
R.sup.5-R.sup.6 combinations with the connecting nitrogen atom
forms a heterocyclic radical; the moiety X is an anion; and the
value of the parameter n is 1 or 2.
4. The method of claim 1, wherein both a neutral and an ionic
guanidine compound are removed from the aqueous media.
5. The method of claim 1, wherein the concentration of guanidine
compound present initially in the aqueous media ranges from about
0.5 parts per million to about 100,000 parts per million.
6. The method of claim 1, wherein the aqueous media is free of
alkali metal halide.
7. The method of claim 1, wherein the aqueous media comprises an
alkali metal halide in an amount of between about 0.01 wt. % and
about 4 wt. %.
8. The method of claim 7, wherein the alkali metal halide is
selected from the group consisting of sodium chloride and potassium
chloride.
9. The method of claim 1, wherein the carbonaceous adsorbent is an
activated carbon.
10. The method of claim 1, wherein the carbonaceous adsorbent is
derived from the pyrolysis of a synthetic resinous polymer.
11. The method of claim 1, wherein the carbonaceous adsorbent is
employed with aqueous media at a pH of greater than 7.
12. The method of claim 1, wherein the adsorbent is a clay selected
from the group consisting of kaolinite, halloysite, dickite,
nacrite, montmorillonite, nontronite, beidellite, hectorite,
saponite, hydromicas, phengite, brammallite, glaucomite,
celadonite, kenyaite, magadite, bentonite, stevensite, muscovite,
sauconite, vermiculite, volkonskoite, laponite, mica, fluoromica,
smectite, and mixtures containing at least one of these clays.
13. The method of claim 1, wherein the clay comprises sodium
montmorillonite.
14. The method of claim 1, wherein the nanofiltration membrane has
a molecular weight cut-off sufficient to retain from about 70% to
about 100% of the guanidine compound.
15. The method of claim 1, wherein calcination is performed at a
temperature in a range of between about 500.degree. C. and about
600.degree. C.
16. The method of claim 1, wherein the concentration of guanidine
compound following removal is less than 30% of the initial
concentration.
17. The method of claim 1, wherein the concentration of guanidine
compound following removal is less than 15% of the initial
concentration.
18. The method of claim 1, further comprising the step of
recovering the guanidine compound.
19. The method of claim 1, wherein an additional inorganic or
organic component is removed in addition to the neutral or ionic
guanidine compound.
20. The method of claim 19, wherein the additional component is
sodium phenylphosphinate.
21. The method of claim 19, wherein the additional component is
chlorophthalic acid.
22. A method for removing a guanidine compound selected from the
group consisting of hexaethylguanidinium chloride,
pentaethylguanidine, and mixtures thereof, from an aqueous media
comprising less than 4 wt. % of an alkali metal halide, wherein the
method is selected from the group consisting of (a) adsorption onto
a carbonaceous adsorbent selected from the group consisting of
activated carbon and a carbonaceous adsorbent derived from the
pyrolysis of a synthetic resinous polymer, (b) adsorption onto a
clay adsorbent, (c) filtration through a nanofiltration membrane
having a molecular weight cut-off sufficient to retain from about
80% to about 100% of the guanidine compound, and (d) removal of
water and calcination at a temperature in a range of between about
500.degree. C. and about 600.degree. C.; wherein the concentration
of guanidine compound present initially in the aqueous media ranges
from about 1 part per million to about 20,000 parts per million,
and wherein the concentration of guanidine compound following
removal is less than 20% of the initial concentration.
23. The method of claim 22, wherein the aqueous media is free of
alkali metal halide.
24. The method of claim 22, wherein the aqueous media comprises an
alkali metal halide in an amount of between about 0.01 wt. % and
about 4 wt. %.
25. The method of claim 24 wherein the alkali metal halide is
selected from the group consisting of sodium chloride and potassium
chloride.
26. The method of claim 22, wherein the carbonaceous adsorbent is
employed with aqueous media at a pH of greater than 7.
27. The method of claim 22 further comprising the step of
recovering the guanidine compound.
28. The method of claim 22, wherein an additional inorganic or
organic component is removed in addition to the neutral or ionic
guanidine compound.
29. The method of claim 28, wherein the additional component is
sodium phenylphosphinate.
30. The method of claim 28, wherein the additional component is
chlorophthalic acid.
31. A method for removing a guanidine compound selected from the
group consisting of hexaethylguanidinium chloride,
pentaethylguanidine, and mixtures thereof, from an aqueous media
optionally comprising an alkali metal halide, wherein the method is
selected from the group consisting of (b) adsorption onto a clay
adsorbent, (c) filtration through a nanofiltration membrane having
a molecular weight cut-off sufficient to retain from about 80% to
about 100% of the guanidine compound, and (d) removal of water and
calcination at a temperature in a range of between about
500.degree. C. and about 600.degree. C.; wherein the concentration
of guanidine compound present initially in the aqueous media ranges
from about 1 part per million to about 20,000 parts per million,
and wherein the concentration of guanidine compound following
removal is less than 20% of the initial concentration.
32. The method of claim 31, wherein the aqueous media is free of
alkali metal halide.
33. The method of claim 31 wherein the alkali metal halide is
present at a level in a range of between about 0.01 wt. % and about
10 wt. %, based on the total weight of the aqueous media.
34. The method of claim 33 wherein the alkali metal halide is
selected from the group consisting of sodium chloride and potassium
chloride.
35. The method of claim 31 further comprising the step of
recovering the guanidine compound.
36. The method of claim 31, wherein an additional inorganic or
organic component is removed from aqueous media in addition to the
neutral or ionic guanidine compound.
37. The method of claim 36, wherein the additional component is
sodium phenylphosphinate.
38. The method of claim 36, wherein the additional component is
chlorophthalic acid.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates a method for removing a
guanidine compound from aqueous media. More particularly, it
relates a method for removing an ionic or a neutral, or both an
ionic and a neutral guanidine compound from aqueous media.
[0002] Guanidine compounds are frequently used as catalysts in
chemical reactions, for example because of their basic properties
in the case of neutral guanidine compounds or because of their
phase transfer catalytic properties in the case of ionic guanidine
compounds (also know as guanidinium salts). In particular examples
U.S. Pat. No. 5,229,482 discloses a displacement method for the
preparation of polyetherimides from bis(chlorophthalimides) and
alkali metal salts of dihydroxy-substituted aromatic hydrocarbons
using a solvent of low polarity such as o-dichlorobenzene in the
presence of a thermally stable phase transfer catalyst such as a
hexaalkylguanidinium halide. U.S. Pat. No. 5,830,974 discloses a
similar method using a monoalkoxybenzene such as anisole as
solvent. Isolation of product from organic media comprising a
guanidine compound often involves washing the organic media with
water. In these cases all or at least a portion of guanidine
compound may transfer to the aqueous phase. For proper disposal of
the wash water and for recovery and reuse of valuable guanidine
compounds, a method is needed to remove a guanidine compound from
the aqueous media.
[0003] U.S. Pat. No. 5,759,406 teaches removal of adsorbates such
as guanidinium salts from brine solution using a
non-ion-exchangeable adsorbent polymeric resin. However, the
polymeric resins show limited adsorption capacity and must be used
in relatively large amounts for efficient removal of the target
adsorbates.
[0004] U.S. Pat. No. 6,214,235 teaches purification of brine
solution for electrolysis by removal of organic salts using
carbonaceous adsorbents. However, the method requires brine
solutions with concentration of salt greater than 5 weight percent
and makes no suggestion for recovery of organic salts. There is a
continuing need for a method to remove guanidine compounds from
aqueous media, particularly for waste water treatment and disposal,
and for recovery of guanidine compounds for further use.
BRIEF DESCRIPTION OF THE INVENTION
[0005] The present inventors have discovered a method for removing
guanidine compounds from aqueous media. The method is efficient and
is also applicable to a wide variety of aqueous media. In one
embodiment the method works surprisingly well for removing a
guanidine compound from aqueous media quite low in ionic strength
as measured by concentration of salt.
[0006] In one of its embodiments the present invention comprises a
method for removing a neutral or an ionic guanidine compound from
an aqueous media comprising less than 4 wt. % of an alkali metal
halide, wherein the method is selected from the group consisting of
(a) adsorption onto a carbonaceous adsorbent, (b) adsorption onto a
clay adsorbent, (c) filtration through a nanofiltration membrane,
and (d) removal of water and calcination.
[0007] In another of its embodiments the present invention
comprises a method for removing a guanidine compound selected from
the group consisting of hexaethylguanidinium chloride,
pentaethylguanidine, and mixtures thereof, from an aqueous media
optionally comprising an alkali metal halide, wherein the method is
selected from the group consisting of (b) adsorption onto a clay
adsorbent, (c) filtration through a nanofiltration membrane having
a molecular weight cut-off sufficient to retain from about 80% to
about 100% of the guanidine compound, and (d) removal of water and
calcination at a temperature in a range of between about
500.degree. C. and about 600.degree. C.; wherein the concentration
of guanidine compound present initially in the aqueous media ranges
from about 1 part per million to about 20,000 parts per million,
and wherein the concentration of guanidine compound following
removal is less than 20% of the initial concentration.
[0008] Various other features, aspects, and advantages of the
present invention will become more apparent with reference to the
following description, examples, and appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0009] In the following specification and the claims which follow,
reference will be made to a number of terms which shall be defined
to have the following meanings. The singular forms "a", "an" and
"the" include plural referents unless the context clearly dictates
otherwise. "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where the event occurs and instances
where it does not. The phrase "waste water" is sometimes used to
refer to aqueous media comprising at least one guanidine compound.
However, it should be understood that the present invention
encompasses methods to treat any aqueous media comprising at least
one guanidine compound.
[0010] The term "guanidine compound" as used in the present
invention describes a composition comprising either an ionic
guanidinium salt or a neutral guanidine compound, or both. In one
embodiment guanidine compounds comprise ionic guanidinium species
of the formula (I): 1
[0011] wherein each of R.sup.2, R.sup.3, R.sup.4, R.sup.5 and
R.sup.6 is independently a primary alkyl radical and R.sup.1 a
primary alkyl or bis(primary alkylene) radical, or at least one of
R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 is hydrogen, or at
least one of the R.sup.1-R.sup.2, R.sup.3-R.sup.4 or
R.sup.5-R.sup.6 combinations with the connecting nitrogen atom
forms a heterocyclic radical; the moiety X is an anion; and the
value of the parameter n is 1 or 2. The moiety X in formula (I) may
be any anion and is preferably an anion of a strong acid,
illustrative examples of which comprise chloride, bromide and
methanesulfonate. Chloride and bromide ions are usually preferred.
The value of n will be 1 or 2 depending upon whether R.sup.1 is
alkyl or alkylene, respectively. 2
[0012] wherein each of R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is
independently a primary alkyl radical and R.sup.1 is a primary
alkyl or bis(primary alkylene) radical, or at least one of the
R.sup.1-R.sup.2 or R.sup.3-R.sup.4 combinations with the connecting
nitrogen atom forms a heterocyclic radical; and the value of the
parameter n is 1 or 2.
[0013] The alkyl radicals suitable as R.sup.1-6 in formulas (I) and
(II) comprise primary alkyl radicals, generally containing about
1-12 carbon atoms. R.sup.1 is usually an alkyl radical of the same
structure or a C.sub.2-12 alkylene radical in which the terminal
carbons are primary; most preferably, it is C.sub.2-6 alkyl or
C.sub.4-8 straight chain alkylene. Alternatively, any combination
of R.sup.1-6 and the corresponding nitrogen atom(s) may form a
heterocyclic radical including, but not limited to, piperidino,
pyrrolo or morpholino.
[0014] As indicated by the dotted bonds in formula (I), the
positive charge in the guanidinium salt is delocalized over one
carbon and three nitrogen atoms. This is believed to contribute to
the salts stability under the relatively high temperature
conditions encountered by the salts in some applications. As a
result, decomposition of the guanidinium salt does not occur or
occurs only to a very minor extent. The results include suppression
of by-product formation and potential for continued use of the
salts via recycle.
[0015] Guanidinium salts include those disclosed in U.S. Pat. Nos.
5,116,975, 5,132,423 and 5,229,482. Hexaalkylguanidinium salts may
be prepared by the reaction of a corresponding urea (e.g., a
tetraalkylurea) with phosgene or phosphorus oxychloride, or by the
reaction of a similar thiourea with an N,N-dialkylcarbamoyl halide,
to yield a chloroformamidinium salt, frequently referred to as a
"Vilsmeier salt", followed by reaction of said salt with a
corresponding amine (e.g., a dialkylamine). Reference is made to
Kantlehner et al., Liebigs Ann. Chem., 1984, pp. 108-126, and
Pruszynski, Can. J. Chem., vol. 65, pp. 626-629 (1987).
alpha,omega-Bis(pentaalkylguanidinium)alkane salts may be similarly
prepared by reaction of the chloroformamidinium salt with a
monoalkylamine, followed by reaction of the resulting
pentaalkylguanidinium salt with an alkylene dihalide. The
alpha,omega-bis(pentaalkylguanidinium)alkane salts defined when
R.sup.1 is alkylene and n is 2 are disclosed, for example, in U.S.
Pat. No. 5,081,298.
[0016] The concentration of guanidine compound initially in aqueous
media ranges from about 0.5 parts per million (ppm) to 100,000 ppm
(10%), by weight of the aqueous media, and preferably ranges from
about 1 ppm to about 20,000 ppm (2%) by weight of the aqueous
media. In particularly preferred embodiments the concentration of
guanidine compound initially in aqueous media ranges from about 1
ppm to about 1000 ppm, or from about 1 ppm to about 500 ppm.
[0017] Aqueous media in the present invention comprises any aqueous
media comprising water and at least one ionic or neutral guanidine
compound, or both of at least one ionic and at least one neutral
guanidine compound. In various embodiments aqueous media may also
comprise any additional components which are water-soluble or at
least partially water-soluble and which arise from or are present
initially in chemical reactions in which a guanidine compound is
present in the capacity of reaction product, reaction byproduct,
decomposition product, reactant or catalyst, or in more than one
capacity. In some particular embodiments aqueous media comprises at
least one guanidine compound which was added as a catalyst in a
displacement reaction, illustrative examples of which include
polymerization reactions. In one particular embodiment aqueous
media comprises both at least one guanidine compound added as a
catalyst in a polymerization reaction and at least one guanidine
compound decomposition product derived from an initial guanidine
compound.
[0018] Guanidine compounds which may be employed as catalysts in
displacement reactions comprise guanidinium salts, illustrative
examples of which include hexaalkylguanidinium salts and
alpha,omega-bis(pentaalky- lguanidinium)alkane salts. In particular
embodiments hexaalkylguanidinium salts and
alpha,omega-bis(pentaalkylguanidinium)alkane salts comprise halogen
salts, particularly bromides and chlorides. In one particular
embodiment a hexaalkylguanidinium salt employed as a catalyst is
hexaethylguanidinium chloride. In another particular embodiment an
alpha,omega-bis(pentaalkylguanidinium)alkane salt employed as a
catalyst is 1,6-bis(penta-n-butylguanidinium)hexane dibromide. In
other particular embodiments guanidinium salts are employed as
catalysts in displacement reactions of bisphenol salts such as
bisphenol A disodium salt with nitro- or halo-substituted imides
such as 4-nitro-N-methylphthalimide, 4-chloro-N-methylphthalimide
or 1,3-bis(N-(4-chlorophthalimido))benzene also known as
2,2'-(1,3-phenylene)bis(5-chloro-1H-isoindole-1,3(2H-dione)- ), to
produce bisimides or polyetherimides. In particular examples U.S.
Pat. No. 5,229,482 discloses a displacement method for the
preparation of polyetherimides from bis(chlorophthalimides) and
alkali metal salts of dihydroxy-substituted aromatic hydrocarbons
using a solvent of low polarity such as o-dichlorobenzene in the
presence of a thermally stable phase transfer catalyst such as a
hexaalkylguanidinium halide. U.S. Pat. No. 5,830,974 discloses a
similar method using a monoalkoxybenzene such as anisole as
solvent.
[0019] In some embodiments an aqueous medium comprising at least
one guanidine compound is formed when a reaction mixture comprising
an organic solvent and at least one guanidine compound is washed
with water. Thus, in some embodiments an aqueous medium comprising
at least one guanidine compound may optionally comprise less than
about 5 wt. % of an organic solvent and any other water-soluble or
partially water-soluble species present in said reaction mixture.
In various embodiments said organic solvent has a boiling point
above about 150.degree. C. and includes as illustrative examples
ortho-dichlorobenzene, para-dichlorobenzene, dichlorotoluene,
1,2,4-trichlorobenzene, diphenyl sulfone, phenetole, anisole and
veratrole, and mixtures thereof. In some embodiments said organic
solvent forms an azeotrope with water.
[0020] In certain types of reactions such as displacement reactions
a salt by-product such as an alkali metal salt may be formed as a
side-product. Thus, in some embodiments an aqueous medium
comprising at least one guanidine compound may optionally comprise
an alkali metal salt, and in particular, sodium chloride or
potassium chloride. When an alkali metal salt is present in the
aqueous media, it is typically present at a level in a range of
between about 0.01 wt. % and about 10 wt. %, based on the total
weight of the aqueous media. In other embodiments when an alkali
metal salt is present in the aqueous media, it is typically present
at less than 5 wt.%, or less than 4 wt. %, or less than 3 wt. %,
based on the total weight of the aqueous media. In some particular
embodiments an alkali metal salt is present in the aqueous media at
a level of between about 0.01 wt. % and about 4 wt. % or at a level
of between about 0.01 wt. % and about 3.5 wt. %, based on the total
weight of the aqueous media. A hexaalkylguanidinium salt may
undergo some dealkylation to form the corresponding
pentaalkylguanidine, for example under displacement reaction
conditions. Thus, in another embodiment an aqueous medium comprises
a first guanidinium salt and one or both of a neutral guanidine
compound and its corresponding protonated analog (that is, a second
guanidinium compound which is the protonated decomposition product
a first guanidinium compound). In another particular embodiment an
aqueous medium comprises hexaethylguanidinium chloride and one or
both of pentaethylguanidine and pentaethylguanidinium chloride (the
protonated decomposition product of hexaethylguanidinium
chloride).
[0021] In other embodiments displacement reaction mixtures may
optionally comprise still other inorganic or organic components in
addition to at least one guanidine compound. Washing said reaction
mixture with water may result in an aqueous medium comprising at
least one guanidine compound and additional components which may be
at least partially water-soluble. Said additional inorganic or
organic components may be removed along with a guanidine compound
from aqueous media by methods of the present invention. Therefore,
it is to be understood that, although removal of a guanidine
compound is referred to, additional organic or inorganic components
may also be present in the aqueous media and may also be removed
using the teachings herein. In a particular embodiment an aqueous
medium may optionally comprise an imidization catalyst used in a
displacement reaction. Suitable imidization catalysts are known in
the art; they include salts of organophosphorus acids, particularly
phosphinates such as sodium phenylphosphinate and heterocyclic
amines such as 4-diaminopyridine. A preferred catalyst is sodium
phenylphosphinate also known as phenyl phosphinic acid, sodium
salt. Imidization catalyst levels in the aqueous media can vary
widely, for example from about 10 ppm to about 5000 ppm. In another
particular embodiment an aqueous medium may optionally comprise an
organic component of a polymerization reaction, such as a monomer
or end-capping agent or a reaction product thereof. In an
illustrative example chlorophthalic acid may be present in aqueous
media obtained by washing a polymerization reaction mixture used to
prepare a polyetherimide. Chlorophthalic acid levels in the aqueous
media can vary widely, for example from about 1 ppm to about 20,000
ppm. In some particular embodiments chlorophthalic acid levels in
the aqueous media can vary from about 1 ppm to about 5,000 ppm, or
from about 1 ppm to about 2,000 ppm.
[0022] In one embodiment of the invention aqueous media is
contacted with a carbon adsorbent to remove a guanidine compound.
Suitable carbon adsorbents may be activated carbons. Activated
carbons can be produced by pyrolyzing organic materials such as
coal, peat, or coconut shells under high temperatures in a
nonoxidizing environment. The raw carbonaceous material can also be
mixed with a binding agent to form a granular material. The
pyrolyzed carbonaceous material can then be activated by steaming
to create a high capacity, high surface area adsorbent. Raw
materials with low metals content are sometimes preferred as they
produce more pure activated carbons with a final lower metals
content although an acid wash step can be used leach some of the
residual metals from the as produced activated carbon. In many
embodiments the carbon is acid washed to prevent leaching of
components from the adsorbent into an acidic solution to be
treated. One suitable activated carbon material that is
commercially available is Type CPG Granular Carbon with particle
size between 12 mesh and 40 mesh (i.e. mesh size 12.times.40),
available from Calgon Carbon Corporation. Other factors useful in
selecting activated carbons include base exchange capacity and
particle size. Optimum activated carbons for treating a particular
guanidine compound-comprising aqueous media may be determined
without undue experimentation by those skilled in the art.
[0023] In another embodiment of the invention a suitable carbon
adsorbent may be derived from the pyrolysis of a synthetic resinous
polymer. Sometimes referred to as hard carbon adsorbents, such
adsorbents and their method of preparation are described, for
example, in U.S. Pat. Nos. 4,040,990 and 4,957,897. As described
therein, these carbons are partially pyrolyzed particles preferably
in the form of hard beads or spheres and having multimodal pore
size, including micro and macro pores. They are produced by the
controlled decomposition of a synthetic polymer. The pyrolysis, as
described in U.S. Pat. No. 4,040,990, is generally conducted in an
inert atmosphere comprised of, for example, helium, argon, or
nitrogen. Any of the many synthetic polymers disclosed in U.S. Pat.
No. 4,040,990 can be employed in preparing the hard carbon
adsorbent for the process of this invention. In some embodiments
suitable polymers are those derived from aliphatic and aromatic
materials which are ethylenically unsaturated. In other embodiments
the polymer is cross-linked, because cross-linking often stabilizes
the polymer thermally and leads to greater carbon yields. In still
other embodiments the polymer contains a carbon-fixing moiety, such
as a cation, anion, strong base, weak base, sulfonic acid,
carboxylic acid, halogen, or alkylamine moiety. Particular examples
of suitable polymers include polylvinylidene chloride, and
macroreticular ion-exchange resins derived from aliphatic and
aromatic materials which are ethylenically unsaturated. In one
particular embodiment the synthetic polymer is a
polystyrene-divinylbenzene sulfonic acid ion-exchange resin. In
addition to the polymers disclosed above, any of the polysulfonated
polymers disclosed in U.S. Pat. No. 4,839,331 can be employed in
preparing a hard carbon adsorbent for processes of the invention.
Suitable hard carbon adsorbents include, but are not limited to,
those commercially available under the name AMBERSORB, available
from Rohm and Haas Co.
[0024] Typically the hard carbon adsorbents are highly stable,
chemically, thermally and physically. In general they have a
surface area of about 100-2000 m.sup.2/g, usually about 500-1200
m.sup.2/g and can be used, for example, in the form of
approximately spherical particles having a mean particle size of,
for example, from about 0.2 to 1.5 mm, preferably from about 0.3 to
1.0 mm.
[0025] In particular embodiments hard carbon adsorbents, which are
prepared by the pyrolysis of a synthetic resinous polymer,
typically contain at least three distinct sets of pores of
differing average size. One set comprises large pores or
macropores, which typically range in size of at least 500 Angstroms
in average diameter. The second set comprises intermediate pores or
mesopores, which typically range in size from about 20 Angstroms to
about 500 Angstroms. The third set and smallest pores or micropores
are typically less than about 20 Angstroms in average diameter;
however, the exact size depends on the temperature of pyrolysis of
the synthetic polymer. In addition to pore size, the pyrolysis
temperature also controls total pore volumes. Generally, as the
pyrolysis temperature increases, the micropore volume
increases.
[0026] The macropore volume of hard carbon adsorbents useful for
this invention are typically at least 0.10 ml/g; preferably in the
range from about 0.10 ml/g to about 0.35 ml/g; more preferably in
the range from about 0.15 ml/g to about 0.30 ml/g; and most
preferably in the range from about 0.20 ml/g to about 0.25 ml/g.
The mesopore volume of hard carbon adsorbents useful for this
invention are typically in the range from about 0.05 ml/g to about
0.30 ml/g; preferably in the range from about 0.10 ml/g to about
0.25 ml/g; and most preferably in the range from about 0.12 ml/g to
about 0.20 ml/g. The micropore volume of hard carbon adsorbents
useful for this invention are at least about 0.10 ml/g; more
preferably, in the range from about 0.20 ml/g to about 0.50 ml/g;
and most preferably in the range from about 0.30 ml/g to about 0.45
ml/g.
[0027] The process for removal of a guanidine compound from aqueous
media using a carbonaceous adsorbent (either activated carbon or
hard carbon adsorbent) can be implemented in accordance with
conventional methods for adsorption processes, for example as
illustrated in U.S. Pat. Nos. 5,094,754 and 5,104,530. In some
particular embodiments said process comprises bringing said aqueous
media into contact with said carbonaceous adsorbent for a time
sufficient to allow a guanidine compound to be adsorbed from said
aqueous media onto said carbonaceous adsorbent; and separating said
aqueous media from said carbonaceous adsorbent containing said
absorbed guanidine compound. In some embodiments the carbonaceous
adsorbents may be used in the form of a slurry or contained in a
column or filter bed. The optimum particle size of the carbon may
depend upon such factors as the particular mode of operation, e.g.
slurrying the carbon with the aqueous media or passing the aqueous
media through a column of activated carbon, and may be determined
without undue experimentation by those skilled in the art. When in
the form of a column or filter bed, the carbonaceous adsorbent bed
may operated in an up flow process or a down flow process. In other
embodiments two or more carbonaceous adsorbent beds may be
connected in series. The process for removal of a guanidine
compound from aqueous media using a carbonaceous adsorbent may be
operated in continuous, semi-continuous or batch mode.
[0028] When a carbon adsorbent is used to remove at least one
guanidine compound from aqueous media, then the pH of the aqueous
media may be in any convenient range, typically between about 1 and
about 13. In some particular embodiments the pH of the aqueous
media is greater than about 7. In other particular embodiments the
pH of the aqueous media is in a range of between about 8 and about
13 or in a range of between about 9 and about 11.
[0029] In another embodiment of the invention aqueous media is
contacted with a clay adsorbent to remove a guanidine compound.
Suitable clays typically comprise layered clays, usually silicate
clays. There is no particular limitation with respect to the
layered clays that may be employed in this invention other than
that they are capable of decreasing the concentration of guanidine
compounds in an aqueous media. Illustrative of such layered clays
that may be employed in this invention include, for instance,
smectite and those of the kaolinite group such as kaolinite,
halloysite, dickite, nacrite and the like.
[0030] The layered clays are preferably natural or synthetic
phyllosilicates, particularly smectic clays. Illustrative examples
include, for instance, halloysite, montmorillonite, nontronite,
beidellite, saponite, volkonskoite, laponite, sauconite, magadite,
kenyaite, bentonite, stevensite, and the like. It is also within
the scope of the invention to employ clays comprising minerals of
the illite group, including hydromicas, phengite, brammallite,
glaucomite, celadonite and the like. Often, the preferred layered
minerals include those often referred to as 2:1 layered silicate
minerals, including muscovite, vermiculite, saponite, hectorite and
montmorillonite, the latter often being most preferred. The clays
may be synthetically produced, but most often they comprise
naturally occurring minerals and are commercially available.
Mixtures containing at least one of the clays as described herein
are also suitable. Other suitable clay adsorbents include those
described in U.S. Pat. No. 5,530,052. Preferred layered clays
comprise particles containing a plurality of silicate platelets
having a thickness of about 7-15 angstroms bound together at
interlayer spacings of about 4 angstroms or less, and containing
exchangeable cations such as Na.sup.+, Ca.sup.+2, K.sup.+,
Al.sup.+3, and/or Mg.sup.+2 present at the interlayer surfaces. The
clays typically have a cation exchange capacity of about 50-200
milliequivalents per 100 grams on a dry basis. In various
embodiments of the invention the clay adsorbents are employed when
predominantly in their alkali metal ion forms and particularly in
their sodium ion forms. Generally, the clays are swollen with an
aqueous solution prior to use to increase their adsorption
capacity.
[0031] The process for removal of a guanidine compound from aqueous
media using a clay adsorbent can be implemented in accordance with
conventional methods for adsorption processes. In some particular
embodiments said process comprises bringing said aqueous media into
contact with said clay adsorbent for a time sufficient to allow a
guanidine compound to be adsorbed from said aqueous media onto said
clay adsorbent; and separating said aqueous media from said clay
adsorbent containing said absorbed guanidine compound. Illustrative
methods of contacting the clay with the aqueous media comprising at
least one guanidine compound include flow through columns and batch
methods. The column method involves passing the aqueous media
through a packed column of clay. Another method is to contact the
clay with the aqueous media in a fluidized bed manner, for example
an upflow of the aqueous media through a bed of clay. Additionally,
stirred beds of clay may be contacted with the aqueous media. In a
batch method of contacting the clay with the aqueous media, the
clay is added to the aqueous media as a finely divided powder and
after a sufficient amount of time is removed by well-known methods,
illustrative examples of which comprise filtration, flocculation,
flotation or centrifugation. In this mode of operation, the
guanidine compound is sorbed on the clay and removed from the
aqueous media when the clay is physically removed.
[0032] In yet another embodiment of the invention aqueous media is
contacted with a nanofiltration membrane to remove a guanidine
compound. Nanofiltration is a known operation in which a solution
or dispersion of a material to be treated is passed over a
nanofiltration separation membrane at a pressure which is generally
in the range of from about 1 to about 5 megapascals (depending upon
the strength of the membrane) to cause the lower molecular weight
materials to pass through the membrane along with the water to form
a permeate and an aqueous phase which does not pass through the
membrane, which is known as a retentate. An increase in pressure
usually increases the rate of permeate formation. However, the
pressure which can be utilized may be determined by such factors as
the temperature, nature of the particular nanofiltration membrane
and the particular design of the nanofiltration apparatus and may
be readily determined without undue experimentation by those
skilled in the art. Upon passage through the nanofiltration module,
the permeate has a lower concentration of the guanidine compound
than the retentate or the initial aqueous media.
[0033] A suitable nanofiltration membrane has a molecular weight
cut-off (MWCO) which is often related to membrane pore size, and
which retains the guanidine compounds while allowing water to pass
through the membrane. The desired MWCO is generally less than the
molecular weight of a guanidine compound in the aqueous media.
Nanofiltration membranes generally have a nominal MWCO of between
about 100 Daltons (Da) and about 5 kilodaltons (kDa), or between
about 100 Da and about 3 kDa, or between about 100 Da and about 1
kDa, or between about 100 Da and about 600 Da, or between about 150
Da and about 600 Da. In some embodiments a suitable nanofiltration
membrane has an MWCO sufficient to retain from about 40% to about
100% of the guanidine compound, preferably from about 70% to about
100% of the guanidine compound, and more preferably from about 80%
to about 100% of the guanidine compound. The process for removal of
a guanidine compound from aqueous media using a nanofiltration
membrane may be operated in continuous, semi-continuous or batch
mode.
[0034] Suitable nanofiltration membranes comprise sintered metal,
ceramics or polymeric materials. Suitable polymeric nanofiltration
membranes may be made, for example, of cellulose, cellulose
acetate, polyamide, aramid, polyether, polysulfone,
polyethersulfone, polyvinylpyrrolidone, polytetrafluoroethylene, or
polyvinylidene fluoride; and are commercially available from
several manufacturers, including Desalination Membrane Products
(Escondido, Calif.), Dow/Film Tec Corporation (Minneapolis, Minn.),
Osmonics (Minnetonka, Minn.), and Membrane Products Kiryat Weizman
Ltd. (Rehovot, Israel). The type of membrane which is selected may
be dependent upon such factors as the pH of the aqueous media to be
treated with the nanofiltration unit, the molecular weight cut-off
required, and the temperature and pressure at which the
nanofiltration is to be carried out.
[0035] In yet another embodiment of the invention aqueous media is
subjected to removal of water and calcination to remove a guanidine
compound. Water may be removed from the aqueous media by any
convenient method. In a particular embodiment water is removed by
evaporation. Evaporation may be conducted at any convenient
pressure, typically at or below atmospheric pressure. Removal of
water typically leaves less than 5 wt. % of the original amount of
water remaining. Following removal of water the substantially solid
residue is subjected to calcination at a temperature of greater
than 400.degree. C. or greater than 450.degree. C. or greater than
500.degree. C. In one embodiment calcination is performed at a
temperature in a range of between about 500.degree. C. and about
600.degree. C. The time of calcination is typically such that
substantially all organic residue comprising a guanidine compound
is burned off. Removal of substantially all organic residue
typically leaves less than 5 wt. % of the original organic residue
remaining. In a particular embodiment removal of substantially all
organic residue typically leaves less than 5 wt. % or less than 2
wt. % of the initial amount of guanidine compound, based on the
weight of guanidine compound initially present in aqueous media. In
some particular embodiments removal of substantially all organic
residue results in no detectable guanidine compound remaining, and
less than 1000 ppm, or less than 500 ppm, or less than 200 ppm
total organic carbon remaining. There are no particular limitations
on the apparatus or protocol for performing calcination.
Calcination may be performed under air or under an inert
atmosphere. Removal of water and calcination may be performed in
continuous, semi-continuous or batch mode. Following calcination
any solid residue may be disposed of in an appropriate manner such
as land-filling.
[0036] Following treatment of aqueous media to remove a guanidine
compound using the method of the invention the concentration of
guanidine compound in aqueous media is less than 50% of the initial
concentration, or less than 30% of the initial concentration, or
less than 25% of the initial concentration, or less than 20% of the
initial concentration, or less than 15% of the initial
concentration, or less than 10% of the initial concentration. In
the case of an aqueous medium treated using a nanofiltration
membrane the final concentrations of guanidine compound refer to
that part of the aqueous medium which has passed through the
membrane. In the case of an aqueous medium treated by removal of
water and calcination of the residue, the final concentrations of
guanidine compound refers to weight percent based on the weight
initially present in the aqueous medium. If so desired, more than
one step or a combination of steps selected from the group
consisting of adsorption onto a carbonaceous adsorbent, adsorption
onto a clay adsorbent, filtration through a nanofiltration
membrane, and removal of water and calcination may be employed for
removal of a guanidine compound from aqueous media.
[0037] Furthermore, following treatment of aqueous media to remove
a guanidine compound, an additional inorganic or organic component
which may optionally be present and which may be concurrently
removed by methods of the present invention along with the
guanidine compound may remain at a concentration in aqueous media
of less than 50% of its initial concentration, or less than 30% of
its initial concentration, or less than 25% of its initial
concentration, or less than 20% of its initial concentration, or
less than 15% of its initial concentration, or less than 10% of its
initial concentration, depending upon such factors as the identity
of the additional component, the type of treatment method, and the
amount of adsorption agent.
[0038] In some embodiments of the invention a guanidine compound
may optionally be recovered from the adsorption media. Any known
means may be used for recovery. In some embodiments a guanidine
compound may be at least partially recovered from a carbonaceous
adsorbent by treating the adsorbent with a boiling aqueous
solution. Optionally, a surfactant may be present in the aqueous
solution to aid in recovery of the guanidine compound. In other
embodiments a guanidine compound may be at least partially
recovered from a carbonaceous or clay adsorbent by treating the
adsorbent with an acidic media, particularly an aqueous acidic
solution, optionally at elevated temperature and optionally
containing a surfactant. Acidic solutions may be derived from
either organic or inorganic acids.
[0039] In yet another embodiment a guanidine compound may be
recovered from an aqueous media in which the guanidine compound has
previously been concentrated through contact of the aqueous media
with a nanofiltration membrane. Illustrative methods for recovering
a guanidine compound from aqueous media include removal of water or
adsorption of the guanidine compound on an adsorbent. Recovered
guanidine compounds may be recycled and reused in chemical
processes, illustrative examples of which include those described
herein above. If necessary, a guanidine compound may be reactivated
before reuse, such as by neutralization in the case of a protonated
guanidine compound or by alkylation in the case of a dealkylated
guanidine compound or by ion exchange in the case of a guanidinium
compound. The carbonaceous and clay adsorbents and the
nanofiltration membranes themselves may optionally be regenerated
and optionally reused.
[0040] Although the invention is illustrated by treatment of waste
water comprising at least one guanidine compound and optionally
additional inorganic or organic components which may be at least
partially water-soluble, it is to be understood that the method of
the invention is also applicable for treatment of waste water
comprising said inorganic or organic components in the absence of
at least one guanidine compound. In particular embodiments the
method of the invention may be used to remove an imidization
catalyst such as sodium phenylphosphinate or an organic component
of a polymerization reaction, such as a monomer or end-capping
agent or a reaction product thereof, illustrative examples of which
include chlorophthalic acid. In other particular embodiments the
method of the invention may be used to remove both an imidization
catalyst such as sodium phenylphosphinate and an organic component
of a polymerization reaction, such as a monomer or end-capping
agent or a reaction product thereof, illustrative examples of which
include chlorophthalic acid.
[0041] Without further elaboration, it is believed that one skilled
in the art can, using the description herein, utilize the present
invention to its fullest extent. The following examples are
included to provide additional guidance to those skilled in the art
in practicing the claimed invention. The examples provided are
merely representative of the work that contributes to the teaching
of the present application. Accordingly, these examples are not
intended to limit the invention, as defined in the appended claims,
in any manner. In the following examples HEGCl is an abbreviation
for hexaethylguanidinium chloride and PEG is an abbreviation for
pentaethylguanidine.
EXAMPLE 1
[0042] In the following examples Calgon CPG acid-washed granular
carbon was pulverized using a cryo-grinder. The pulverized carbon
was sieved and particles of less than 325 mesh were collected and
dried at 150.degree. C. for 4 hours for use in isotherm
experiments. Said carbon is referred to hereinafter as sieved
Calgon CPG carbon. Unless adjusted by the addition of acid or base,
the pH of the waste water samples was generally in a range of
between about 3 and 5.
[0043] A waste water sample comprised 3.2 wt. % sodium chloride,
348 milligrams per liter (mg/L) of HEGCl and 72 mg/L of PEG. Six
waste water samples (10 milliliters (ml) each) were individually
treated with 50 mg. sieved Calgon CPG carbon and agitated for
various periods of time at room temperature in a mechanical shaker.
The samples were filtered and the filtrates were analyzed for
concentration of HEGCl and PEG versus time. Values are given in
Table 1. The data show the equilibrium is reached very quickly
(less than about 5 minutes).
1TABLE 1 Time (minutes) conc. HEGCl (mg/ml) conc. PEG (mg/ml) 0
0.35 0.07 5 0.04 0.01 10 0.04 0.01 30 0.04 0.01 60 0.05 0.01 90
0.04 0.01
EXAMPLE 2
[0044] For determination of adsorption isotherms sieved Calgon CPG
carbon was dried at 150.degree. C. for 4 hours and then added in
varying amounts in grams per liter (g/L) to waste water samples as
described in Example 1. The samples were agitated for 15 minutes at
room temperature in a mechanical shaker. The samples were filtered
and the filtrates were analyzed to provide amount of HEGCl and PEG
adsorbed per unit weight to adsorbent versus concentration of
adsorbent in the mixture. Values are given in table 2.
[0045] Some conclusions may be drawn from the data in Table 2. From
linear extrapolation the adsorptive capacity of the carbon
adsorbent was found to be approximately 78 mg. HEGCl per gram
Calgon CPG adsorbent when equilibrium had been established under
the specified conditions. Somewhere between about 65 mg. and about
100 mg. of carbon removed essentially all traces of HEGCl and PEG
from 10 ml. waste water containing these particular concentrations
of waste water components.
2TABLE 2 Wt. of Concentration mg. mg. HEGCl Concentration mg. PEG
carbon of HEGCl in HEGCl adsorbed per of PEG in mg. PEG adsorbed
per (g/L) solution (mg/L) adsorbed gram of carbon solution (mg/L)
adsorbed gram of carbon 0 347.7 -- -- 72 -- -- 0.51 303.5 44.2 86.7
65.4 6.6 12.9 1.01 280.2 67.5 66.8 59.7 12.3 12.2 2.05 200 147.7
72.0 40.7 31.3 15.2 3.54 107.54 240.2 67.8 21.4 50.6 14.3 5.03 55.2
292.5 58.2 11.5 60.5 12.0 6.54 15 332.7 50.9 3.8 68.2 10.4 10.03 0
347.7 34.7 0 72 7.2 24.93 0 347.7 13.9 0 72 2.9 50.1 0 347.7 6.9 0
72 1.4 100 0 347.7 3.5 0 72 0.7
EXAMPLE 3
[0046] A waste water sample comprised 3.2 wt. % sodium chloride,
237 milligrams per liter (mg/L) of HEGCl and 46 mg/L of PEG.
Samples of the waste water (10 ml. each) were treated with 50 mg.
unpulverized Calgon CPG carbon. The pH of each mixture was adjusted
to some value by the optional addition of either concentrated
aqueous hydrochloric acid or 50% aqueous sodium hydroxide solution.
Each mixture was agitated for 1 hour at room temperature in a
mechanical shaker. The samples were filtered and the filtrates were
analyzed for concentration of HEGCl and PEG. Values are given in
Table 3. The data in Table 3 show that, as the pH is increased, the
amounts of both ionic and neutral guanidine species adsorbed by the
carbon adsorbent increases.
3TABLE 3 mg. HEGCl adsorbed mg. PEG adsorbed pH per gram of carbon
per gram of carbon 1 40 9 3.5 46 10 13 62 14
EXAMPLE 4
[0047] A waste water sample comprised 237 milligrams per liter
(mg/L) of HEGCl and 46 mg/L of PEG. Samples of the waste water (10
ml. each) were treated with 50 mg. unpulverized Calgon CPG carbon.
Varying amounts of sodium chloride were dissolved in each mixture.
Each mixture was agitated for 1 hour at room temperature in a
mechanical shaker. The samples were filtered and the filtrates were
analyzed for concentration of HEGCl and PEG. Values are given in
Table 4. The data in Table 4 show that, as the polarity of the
solution is increased through addition of increasing amounts of
salt, the amounts of both ionic and neutral guanidine species
adsorbed by the carbon adsorbent increases, although the % increase
diminishes at higher salt level.
4TABLE 4 Wt. % mg. HEGCl adsorbed mg. PEG adsorbed NaCl per gram of
carbon per gram of carbon 0 33 8 3.2 47 10 6.4 52 11
EXAMPLE 5
[0048] A waste water sample with composition similar to that
described above except comprising 6.4 wt. % sodium chloride was
adjusted to pH 13 with 50% aqueous sodium hydroxide, treated with
varying amounts of sieved Calgon CPG carbon and agitated for 1 hour
at room temperature in a mechanical shaker. The sample was filtered
and the filtrates was analyzed for concentration of HEGCl and PEG.
Values are given in Table 5. From linear extrapolation the
adsorptive capacity of the carbon adsorbent under these specified
conditions was found to be approximately 139 mg HEGCl per gram of
carbon adsorbent when equilibrium had been established.
5TABLE 5 Wt. of Concentration mg. mg. HEGCl Concentration mg. PEG
carbon of HEGCl in HEGCl adsorbed per of PEG in mg. PEG adsorbed
per (g/L) solution (mg/L) adsorbed gram of carbon solution (mg/L)
adsorbed gram of carbon 0 361 -- -- 68 -- -- 0.6 285 76 127 44 24
40 1.2 225 136 113 24 44 37 2.3 93 268 116 6 62 27 3.7 17 344 93 1
67 18 5.8 4 357 62 0 68 12
EXAMPLE 6
[0049] In the following examples AMBERSORB 572, a carbonaceous
adsorbent with surface area of about 1100 square meters per gram
(m2/g), was obtained from Rohm and Haas in mesh size of 20-50, and
was used as received. A waste water sample comprised 3.2 wt. %
sodium chloride, 348 mg/L of HEGCl and 78 mg/L of PEG. For
determination of adsorption isotherms AMBERSORB 572 carbon was
dried at 150.degree. C. for 4 hours and then added in varying
amounts in grams per liter (g/L) to individual waste water samples
as described in Example 1. The samples were agitated for 15 minutes
at room temperature in a mechanical shaker. The samples were
filtered and the filtrates were analyzed to provide amount of HEGCl
and PEG adsorbed per unit weight of adsorbent versus concentration
of adsorbent in the mixture. Values are given in Table 6.
[0050] Some conclusions may be drawn from the data in Table 6. From
linear extrapolation the adsorptive capacity of the carbon
adsorbent was found to be approximately 138 mg. HEGCl per gram of
AMBERSORB 572 adsorbent when equilibrium had been established under
the specified conditions. Somewhere between about 50 mg. and about
80 mg. of carbon removed essentially all traces of HEGCl and PEG
from 10 ml. of waste water containing these particular
concentrations of waste water components.
6TABLE 6 Wt. of Concentration mg. mg. HEGCl Concentration mg. PEG
carbon of HEGCl in HEGCl adsorbed per of PEG in mg. PEG adsorbed
per (g/L) solution (mg/L) adsorbed gram of carbon solution (mg/L)
adsorbed gram of carbon 0 366 -- -- 73 -- -- 0.5 281 85 170 49 24
48 0.9 248 118 131 41 32 35 2.1 165 201 96 23 50 23 3.4 83 283 83 7
66 19 5.7 6 360 63 0 73 12 7.8 0 366 47 0 73 9
EXAMPLES 7-8 AND COMPARATIVE EXAMPLES 1-5
[0051] Individual waste water samples (30 ml. each) comprising 3.2
wt. % sodium chloride, 366 mg/L of HEGCl and 73 mg/L of PEG were
stirred with 150 mg. of an adsorbent over 17 hours at ambient
temperature. The samples were filtered and the filtrates were
analyzed for amount of HEGCl and PEG in the mixture. Values are
given in Table 7. Comparative Examples are designated "C.Ex.". The
following adsorbents were used: AMBERSORB 572 ("A"); Calgon CPG
("B"); AMBERSORB 563 ("C"), a carbonaceous adsorbent with BET
surface area of about 550 m.sup.2/g and about 62% of its pore
volume associated with pores less than 2 nanometers (nm) and about
38% of its pore volume associated with pores of diameter greater
than 2 nm and less than 30 nm.; AMBERLITE XAD-2 ("D") a
non-ion-exchangeable adsorbent polymeric resin comprising
structural units derived from styrene cross-linked with
divinylbenzene; AMBERLITE XAD-4 ("E") a non-ion-exchangeable
adsorbent polymeric resin comprising structural units derived from
styrene cross-linked with divinylbenzene and having a surface area
of about 750 m .sup.2/g and an average pore diameter of about 100
angstroms (.ANG.); AMBERLITE XAD-7 ("F") a non-ion-exchangeable
adsorbent polymeric resin having methyl methacrylate units rather
than styrene units and having a surface area of about 450
m.sup.2/g; and AMBERLITE XAD-16 ("G") a non-ion-exchangeable
adsorbent polymeric resin comprising structural units derived from
styrene cross-linked with divinylbenzene and having a surface area
of about 800 square meters per gram (m.sup.2/g) and an average pore
diameter of about 150 angstroms (.ANG.).
7TABLE 7 mg/L HEGCl % HEGCl mg/L PEG % PEG Example Adsorbent
remaining removed remaining removed Ex. 7 A 9 98 1 99 Ex. 8 B 55 85
11 85 C. Ex. 1 C 273 25 48 34 C. Ex. 2 D 166 55 30 59 C. Ex. 3 E
207 43 43 41 C. Ex. 4 F 346 5 68 7 C. Ex. 5 G 202 45 42 42
[0052] The data in Table 7 show that the non-ion-exchangeable
adsorbent polymeric resins (Comparative Examples 2-5) have less
capacity for adsorption of guanidine species than do the
carbonaceous adsorbents of Examples 7 and 8. In comparing Example 7
with Comparative Example 1 it is evident that the carbonaceous
adsorbent with the higher surface area has a higher capacity for
adsorption of guanidine species.
EXAMPLE 9
[0053] An aqueous solution comprising HEGCl and PEG was subjected
to filtration through a nanofiltration membrane comprising
polytetrafluoroethylene (Osmonics type DK-5). The membrane pore
size was such that it rejects 98% magnesium sulfate. The
experimental protocol employed a standard membrane test cell
(SEPA-CF test apparatus) in which wastewater at pH 1 was pumped in
a crossflow manner across the surface of the membrane in a
continuous fashion at a pressure of 276-310 kilopascals and flow
rate of 2 liters per minute with 2 hour cycle time. Permeate flux
was measured volumetrically and HEGCl/PEG concentrations in
permeate and retentate were measured via ion chromatography. Data
are shown in Table 8. The difference between "Feed" amount and the
sum of "Retentate" and Permeate" represents experimental error. The
data show that the concentration of guanidine species in the
permeate is approximately 7-8 times lower than the initial
concentration of said species in the feed.
8 TABLE 8 Sample Amount (grams) HEGCl (ppm) PEG (ppm) Feed 332 3021
931 Retentate 195 4300 1345 Permeate 149 384 120
EXAMPLES 10-18
[0054] Sodium montmorillonite (type KUNIPIA-F; sometimes referred
to herein after as "clay") was obtained from Kunimine Industries,
Japan, and had a cation exchange capacity of 119 milliequivalents
of sodium per 100 grams of clay on a basis of 90% dry weight of
clay. Simulated waste water solutions were prepared by dissolving
various amounts of HEGCl in deionized water. Varying equivalent
amounts of sodium montmorillonite were suspended in water in a
high-speed blender and the HEGCl solution was added thereto under
various conditions with agitation at room temperature. The mixtures
were filtered and the filtrates were analyzed by ion chromatography
for amount of HEGCl remaining. Values are given in Table 9. The
abbreviation "equiv." means "equivalents". The column for
"Conditions" includes the time of agitation.
9TABLE 9 Con- Con- centration centration of HEGCl of HEGCl %
initially remaining HEGCl Example (mg/L) (mg/L) removal Conditions
10 606 175 71 1 equiv. clay; 10 min. 11 556 25 96 2 equiv. clay; 15
min. 12 392 21 95 2 equivs. clay; 15 min.; clay mixture added to
HEGCl soln. 13 392 21 95 Ex. 12 after 1 day aging 14 392 19 95
Ex.12 after 4 days aging 15 392 38 90 0.1 ml. HNO.sub.3 added to
100 ml. soln. after agitation 16 43 18 58 1 equiv. clay; 10 min. 17
40 5 88 2 equiv. clay; 10 min. 18 513 8 98 3 equiv. clay; 10
min.
[0055] The data in Table 9 shows that greater than 1 equivalent of
clay is necessary for efficient removal of HEGCl from solution
under the conditions of the experiment. Little increase in HEGCl
adsorption is obtained upon prolonged standing of the sample with
clay (Examples 13-14).
EXAMPLES 19-22
[0056] Sodium montmorillonite was used as in Examples 10-18.
Individual waste water samples comprising 366 mg/L of HEGCl; 73
mg/L of PEG and optionally 3.2 wt. % sodium chloride as noted were
treated with 2 equivalents clay (based on HEGCI) and agitated under
different conditions. The mixtures were filtered and the filtrates
were analyzed by ion chromatography for amount of HEGCl and PEG
remaining. Values are given in Table 10. The abbreviation "rt"
means "room temperature".
10TABLE 10 Con- Conc. of centration HEGCl % of PEG remaining HEGCl
remaining % PEG Ex. (mg/L) removal (mg/L) removal Conditions 19 51
86 11 85 10 min. in blender at rt 20 111 70 27 63 3.2 wt. % NaCl;
shake overnight at rt 21 154 58 29 60 3.2 wt. % NaCl in blender for
10 min. at rt 22 100 73 36 51 3.2 wt. % NaCl in blender for 10 min.
at 80.degree. C.
EXAMPLES 23
[0057] Waste water samples comprised HEGCl, PEG and sodium
phenylphosphinate (SPP). Samples of the waste water (20 ml. each)
were adjusted to either pH 1.9 or pH 13.9 with hydrochloric acid or
aqueous sodium hydroxide, and treated with various amounts of
pulverized Calgon CPG carbon. Each mixture was agitated for 1 hour
at room temperature in a mechanical shaker. The samples were
filtered and the filtrates were analyzed for concentration of
HEGCI, PEG and SPP. Values are given in Table 11 compared to the
initial concentration of the measured components. The data in Table
11 show that, as the pH is increased, the amounts of both ionic and
neutral guanidine species and of SPP adsorbed by the carbon
adsorbent increases.
11TABLE 11 Carbon weight, HEGCl, PEG, SPP, pH grams/20 ml. ppm ppm
ppm 13.9 0 646 168 123 13.9 0.05 370 58 80 13.9 0.1 98 23 18 13.9
0.15 54 18 18 13.9 0.2 0 17 7 13.9 0.25 0 0 3 1.9 0 675 169 116 1.9
0.05 -- -- 85 1.9 0.1 512 92 53 1.9 0.15 96 21 22 1.9 0.2 71 17 16
1.9 0.25 31 4 4 1.9 0.3 0 0 2
EXAMPLE 24
[0058] In the following examples a reactivated Chemviron carbon
(grade F400) was pulverized using a cryo-grinder. Individual waste
water samples (20 ml. each) comprising chlorophthalic acid (ClPA)
were treated with various amounts of carbon at pH 4. Each mixture
was agitated for 1.5 hour at room temperature in a mechanical
shaker. The samples were filtered and the filtrates were analyzed
for concentration of CIPA. Values are given in Table 12 compared to
the initial concentration of the measured component.
12 TABLE 12 Carbon weight, g/L ClPA, mg/L 0 1007 0.5 863 1.5 565
2.5 373 5 60 7.5 13 10 0 12.5 0 15 0
EXAMPLE 25
[0059] A 2.1 liter waste water sample comprising 1000 ppm total
HEGCl and PEG, 253 ppm SPP, and 2404 ppm total organic carbon was
evaporated to dryness by distillation to yield 170 g residue and
1.8 liters distillate. Analysis of the distillate showed no
detectable HEGCl, PEG, or SPP. A 70 g sample of solid residue was
heated in a stationary furnace under flowing nitrogen at a heating
rate of 50.degree. C. per minute to a temperature of 600.degree. C.
and held at 600.degree. C. for 6 hours. Analysis showed that the
residue weighed 67.92 g and had 100 ppm total organic carbon with
no detectable HEGCl, PEG, or SPP.
[0060] While the invention has been illustrated and described in
typical embodiments, it is not intended to be limited to the
details shown, since various modifications and substitutions can be
made without departing in any way from the spirit of the present
invention. As such, further modifications and equivalents of the
invention herein disclosed may occur to persons skilled in the art
using no more than routine experimentation, and all such
modifications and equivalents are believed to be within the spirit
and scope of the invention as defined by the following claims. All
Patents cited herein are incorporated herein by reference.
* * * * *