U.S. patent application number 15/507100 was filed with the patent office on 2017-10-26 for sorbent for binding metals and production thereof.
This patent application is currently assigned to INSTRACTION GMBH. The applicant listed for this patent is INSTRACTION GMBH. Invention is credited to CHRISTIAN MEYER, THOMAS SCHWARZ, MARTIN WELTER.
Application Number | 20170304803 15/507100 |
Document ID | / |
Family ID | 54106291 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170304803 |
Kind Code |
A1 |
MEYER; CHRISTIAN ; et
al. |
October 26, 2017 |
SORBENT FOR BINDING METALS AND PRODUCTION THEREOF
Abstract
The present invention relates to a sorbent which is suitable for
binding metals from solutions, the production of a corresponding
sorbent as well as the use of the sorbent for binding metals from
solutions.
Inventors: |
MEYER; CHRISTIAN;
(SCHWETZINGEN, DE) ; WELTER; MARTIN; (HEIDELBERG,
DE) ; SCHWARZ; THOMAS; (KOLN, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INSTRACTION GMBH |
MANNHEIM |
|
DE |
|
|
Assignee: |
INSTRACTION GMBH
MANNHEIM
DE
|
Family ID: |
54106291 |
Appl. No.: |
15/507100 |
Filed: |
August 28, 2015 |
PCT Filed: |
August 28, 2015 |
PCT NO: |
PCT/EP2015/001754 |
371 Date: |
February 27, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C02F 1/285 20130101;
B01J 20/3204 20130101; B01J 20/345 20130101; B01J 20/3425 20130101;
B01J 20/3274 20130101; B01J 20/3282 20130101; B01J 20/321 20130101;
B01J 20/3225 20130101; C02F 1/288 20130101; B01J 20/3475 20130101;
C02F 2101/20 20130101; B01J 20/267 20130101; B01J 20/3293
20130101 |
International
Class: |
B01J 20/32 20060101
B01J020/32; C02F 1/28 20060101 C02F001/28; B01J 20/32 20060101
B01J020/32; B01J 20/32 20060101 B01J020/32; B01J 20/32 20060101
B01J020/32; B01J 20/32 20060101 B01J020/32; B01J 20/34 20060101
B01J020/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2014 |
DE |
10 2014 012 566.1 |
Claims
1. Sorbent, comprising a porous support material coated with an
amino group-containing polymer, wherein the concentration of the
amino groups of the sorbent determined by titration is at least 600
.mu.mol/mL, based on the total volume of the sorbent.
2. Sorbent according to claim 1, wherein the ratio of the mass of
the amino group-containing polymer to the total volume of the pores
of the porous support material is greater than or equal to 0.1
g/mL.
3. Sorbent according to claim 1, wherein the pore volume of the
porous support material lies in the range from 30 to 90 vol. %,
based on the total volume of the porous support material.
4. Sorbent according to claim 1, wherein the porous support
material has an average pore size in the range from 6 nm to 400
nm.
5. Sorbent according to claim 1, wherein the porous support
material comprises an organic polymer, an inorganic material or a
composite material of organic polymer and inorganic material.
6. Sorbent according to claim 1, wherein the amino group-containing
polymer is a polyalkylamine.
7. Sorbent according to claim 1, wherein the amino group-containing
polymer is a crosslinked polymer and/or is present not covalently
linked with the porous support material.
8. Process for the production of a sorbent, which comprises the
following steps: (a) providing a porous support material; (b)
applying an amino group-containing polymer onto the porous support
material by a pore filling method; (c) removing solvent used in the
pore filling method; (d) repeating steps (b) and (c); and (e)
crosslinking of the amino group-containing polymer.
9. Process according to claim 8, wherein the steps (b) and (c) are
repeated before the step (e) sufficiently often that the
concentration of the amino groups of the sorbent determined after
step (e) by titration is at least 600 .mu.mol/mL, based on the
total volume of the sorbent.
10. Process according to claim 8, wherein the ratio of the mass of
the amino group-containing polymer to the total volume of the pores
of the porous support material after step (d) is greater than or
equal to 0.1 g/mL.
11. Process according to claim 8, wherein step (c) is performed at
a temperature in the range from 40 to 80.degree. C. and/or a
pressure in the range from 0.01 bar to 1 bar.
12. Process according to claim 8, wherein the concentration of the
amino group-containing polymer in the solvent used for the pore
filling method in step (b) lies in the range from 5 g/L to 200
g/L.
13. Process according to claim 8, wherein in a step (f) an organic
residue which has the nature of a Lewis base is bound onto the
amino group-containing polymer.
14. Sorbent which is obtainable according to a process of claim
8.
15. A process for binding metals from solutions, comprising
contacting a solution containing metal with a sorbent, wherein the
sorbent is a porous support material coated with an amino
group-containing polymer, wherein the concentration of the amino
groups of the sorbent determined by titration is at least 300
.mu.mol/mL.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the National Stage filing of
International Appln. No. PCT/EP2015/001754, filed 28 Aug. 2015, and
claims priority of German Application No. 10 2014 012 566.1, filed
29 Aug. 2014, the entirety of which applications are incorporated
herein by reference for all purposes.
[0002] The present invention relates to a sorbent which is suitable
for binding metals from solutions, the production of a
corresponding sorbent as well as the use of the sorbent for binding
metals from solutions.
[0003] The removal or extraction or recovery of metals, in
particular heavy metals, from industrial waste waters, for example
at plating plants, from catalyst residues from the petrochemical or
pharmaceutical industry, from pit water for example from mines, the
renaturation of heavy metal-polluted soils etc. is an increasingly
important problem since heavy metals in particular either have a
harmful effect on the environment and also their recovery is of
economic interest. In other words, on the one hand environmental
aspects are the priority, and on the other, the provision of
valuable metals, the availability of which is becoming increasingly
doubtful or the price of which is rising is also of great interest.
A further important field of use of sorbents for the removal or
extraction or recovery of metals or heavy metals is the removal of
these in drinking water purification and also in seawater
desalination. Likewise, the removal of heavy metals from
concentrated salt solutions, such as are used in chloralkali
electrolysis or similar processes, is also of great interest.
[0004] For the said areas of use, previously known phases/sorbents
often do not have adequate binding capacity for binding the metals
to be bound on a sufficient scale for example from high
concentration or low concentration solutions or strongly acidic
solutions, in particular also in the presence of alkali or alkaline
earth metal ions. Furthermore, previously known phases often do not
exhibit stability over the whole range from pH 0 to pH 14. A
further disadvantage of many previously known phases is that the
desired metal can indeed be bound, but cannot be recovered simply
or indeed at all from the sorbent used. Owing to the mostly
unsatisfactory binding capacity of known sorbents/phases, a high
sorbent/phase volume is often required, as a result of which the
metal binding processes are very elaborate and cost-inefficient.
Further, owing to the mostly low binding capacity of known
metal-binding sorbents, repeated operation of the process is
necessary in order for example to be able to provide heavy
metal-free water as drinking water.
[0005] It was therefore the object of the present invention to
provide a novel sorbent which partly or wholly does not exhibit the
aforesaid disadvantages. In particular, it is an object of the
present invention to provide a sorbent with a high binding capacity
towards metals, in particular heavy metals and noble metals, per
gram or per millilitre. Preferably, the sorbent provided according
to the invention is in particular renewable with sodium hydroxide,
or allows the recovery of the metals in a simple manner. A further
object of the present invention is to provide a sorbent which still
has a relatively high binding capacity towards metals even under
acidic conditions.
[0006] Furthermore, compared to the metal binding-sorbents known
from the state of the art, the volume of the sorbent used for the
metal binding should be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1 and 2: FIGS. 1 and 2 show the comparison of the
isotherms of the sorbents from Example 1 and comparison example 1
in the binding of copper from aqueous solutions according to
Example 2.
[0008] FIG. 3: FIG. 3 shows the metal binding capacity of the
sorbent from Example 1 for the metals copper, nickel and chromium
as a function of the metal concentration according to Example
3.
[0009] FIG. 4: FIG. 4 shows the quantity of absorbed copper [g] per
quantity of sorbent [kg] in the presence of different
concentrations of NaCl according to Example 4.
[0010] FIGS. 5 and 6: FIGS. 5 and 6 show the variation over time
from Example 5 for the absorption of copper of a sorbent from
Example 1.
[0011] FIG. 7: FIG. 7 shows the binding capacity for copper after
regeneration of the sorbent after various cycles according to
Example 6.
[0012] FIG. 8: FIG. 8 shows the comparison of the copper binding by
multiply coated sorbents with a singly coated sorbent according to
Example 7.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0013] In one embodiment of the present invention, a sorbent
comprises a porous support material coated with an amino
group-containing polymer, wherein the concentration of the amino
groups of the sorbent determined by titration is at least 600
.mu.mol/mL, based on the total volume of the sorbent.
[0014] In a further embodiment of the present invention it is
preferred that the concentration of the amino groups of the sorbent
determined by titration is at least 800 .mu.mol/mL, more preferably
at least 1000 .mu.mol/mL, still more preferably at least 1200
.mu.mol/mL and most preferably at least 1500 .mu.mol/mL sorbent.
The upper limit of the concentration of the amino groups of the
sorbent according to the invention determined by titration is
limited by the spatial feasibility or the maximum possible density
of the arrangement of the amino groups in the amino
group-containing polymer and is at most about 4000 .mu.mol/mL, more
preferably 3000 .mu.mol/mL and most preferably about 2500
.mu.mol/mL. The concentration of the amino groups of the sorbent
determined by titration is understood to mean the concentration
which is obtained according to the analytical method stated in the
examples section of this application by breakthrough measurement
with 4-toluenesulphonic acid.
[0015] Furthermore, it is preferred that the sorbent according to
the invention has a ratio of the mass of the amino group-containing
polymer to the total volume of the pores of the porous support
material of greater than or equal to 0.1 g/mL, more preferably
greater than or equal to 0.125 g/mL, still more preferably of
greater than or equal to 0.15 g/mL and most preferably greater than
or equal to 0.20 g/mL. Here too, physical limits are set to the
upper limit of the said ratio, however preferably about at most 0.5
g/mL, more preferably at most 0.4 g/mL and most preferably at most
0.3 g/mL.
[0016] The mass of the amino group-containing polymer can be
determined by the increase in the tamped density compared to the
support material according to DIN 53194. The total volume of the
pores [V] of the porous support material can be determined by the
solvent absorption capacity (WAC) of the porous support material.
The pore volume [vol. %] can also be determined likewise. Here, in
each case, this is the volume of the freely accessible pores of the
support material, since only this can be determined via the solvent
absorption capacity. The solvent absorption capacity states what
volume of a solvent is necessary to fill the pore space of one gram
of dry sorbent (preferably stationary phase) completely. As the
solvent here, both pure water or aqueous media and also organic
solvents such as dimethylformamide can be used. If the sorbent
increases its volume (swelling) on wetting, the quantity of solvent
used for this is automatically detected. For the measurement of the
WAC, an exactly weighed quantity of dry sorbent is thoroughly
wetted with an excess of effectively wetting solvent and excess
solvent is removed from the inter-particle volume by
centrifugation. During this, solvent within the pores of the
sorbent is retained. The mass of the retained solvent is determined
by weighing and converted into the volume via the density. The WAC
of a sorbent is reported as volume per gram dry sorbent (mL/g).
[0017] The coating of the amino group-containing polymer on the
porous support material is preferably present in the form of a
hydrogel. This is in particular because the amino group-containing
polymer has the aforesaid high concentration of amino groups. A
hydrogel is here understood to mean a solvent- (preferably water-)
containing, but solvent-soluble polymer, the molecules of which are
chemically, e.g. by covalent or ionic bonds, or physically, e.g. by
entanglement of the polymer chains, linked into a three-dimensional
network. Because of built-in polar (preferably hydrophilic) polymer
components, they swell in the solvent (preferably water) with
considerable volume increase, without however losing their material
cohesion. It is known of hydrogels from the state of the art that
they to some extent lose their properties irreversibly when they
are dried. In the present application, however, the hydrogels do
not lose their properties, since they are chemically and
mechanically stabilized by the porous support material. The amino
group-containing coating is then present in particular as a
hydrogel in the sorbent according to the invention, if this is
present swollen in a solvent, i.e. in particular during the use for
the binding of metals from solutions described below.
[0018] The porous support material is preferably a mesoporous or
macroporous support material. The average pore size of the porous
support material preferably lies in the range from 6 nm to 400 nm,
more preferably in the range from 10 to 300 nm and most preferably
in the range from 20 to 150 nm. A pore size in the stated range is
important in order to ensure that the binding capacity is
sufficiently high. For the case of too small a pore size, the amino
group-containing polymer on the surface of the porous support
material can block the pores and the internal volume of the pores
is not filled with amino group-containing polymer. Furthermore, it
is preferred that the porous support material has a pore volume in
the range from 30 to 90 vol. %, more preferably from 40 to 80 vol.
% and most preferably from 60 to 70 vol. %, in each case based on
the total volume of the porous support material.
[0019] The average pore size of the porous support material can be
determined by the pore filling method with mercury according to DIN
66133.
[0020] The porous support material can comprise an organic polymer,
an inorganic material or a composite material of organic polymers
and inorganic materials or consist thereof.
[0021] In order to be able to provide a sorbent which has a high
sorbent stability over a range from pH 0 to pH 14, it is preferred
if the porous support material is an organic polymer.
[0022] Preferably, the organic polymer for the porous support
material is selected from the group which consists of polyalkyl,
preferably with an aromatic unit in the side-chain (that is, bound
to the polyalkyl chain), polyacrylate, polymethacrylate,
polyacrylamide, polyvinyl alcohol, polysaccharides (e.g. starch,
cellulose, cellulose esters, amylose, agarose, sepharose, mannan,
xanthan and dextran), as well as mixtures thereof. Most preferably,
the organic polymer is polystyrene or a derivative of polystyrene,
which is preferably a copolymer of polystyrene (or derivative of
polystyrene) and divinylbenzene. If the organic polymer bears an
aromatic unit, then this is preferably present sulphonated. In a
quite particularly preferred embodiment of the present invention,
the organic polymer is a sulphonated crosslinked
poly(styrene-co-divinylbenzene) or a derivative thereof.
[0023] If the porous support material is an inorganic material, or
it comprises an inorganic material, the inorganic material is
preferably an inorganic mineral oxide selected from the group which
consists of silicon oxide, aluminium oxide, magnesium oxide,
titanium oxide, zirconium oxide, fluorosil, magnetite, zeolites,
silicates (e.g. kieselguhr), mica, hydroxyapatite, fluoroapatite,
metal-organic base structures, ceramics, glass, porous glass (e.g.
Trisoperl), metals, e.g. aluminium, silicon, iron, titanium,
copper, silver and gold, graphite and amorphous carbon.
Particularly preferably, the inorganic porous support material is a
silicon dioxide or aluminium oxide, in particular silicon dioxide.
The silicon dioxide is preferably silica gel.
[0024] In particular for reasons of the use in a wide pH range, in
particular in the basic range, the porous support material is
preferably an organic polymer.
[0025] The porous support material used according to the invention
can be of homogeneous or heterogeneous composition, and therefore
in particular incorporates materials which are made up of one or
more of the aforesaid materials, for example in multilayer
compositions.
[0026] The porous support material is preferably a particulate
material with an average particle size in the range from 5 to 2000
.mu.m, more preferably in the range from 10 to 1000 .mu.m. The
porous support material can also be a lamellar or fibrous material,
such as for example a membrane or a foam. The external surface of
the porous support material can thus be flat (lamellae, films,
discs, membranes, fibre fabric or non-fibrous fabric) or curved
(either concave or convex: spherical, granules, (hollow) fibres,
tubes or capillaries).
[0027] As mentioned above, the porous support material is coated
with an amino group-containing polymer which consists of individual
polymer chains or comprises these. The polymer chains are
preferably covalently linked together. The amino group-containing
polymer is preferably not covalently linked with the surface of the
porous support material.
[0028] The use of a non-covalently surface-bound crosslinked
polymer as amino group-containing polymer on the porous support
material also has the following three advantages: (1) flexibility
of the polymer, since it is not covalently bound to the surface of
the porous support material; (2) the crosslinking of the amino
group-containing polymer ensures that the film remains on the
surface of the porous support material and is not lost during the
use of the sorbent; (3) the thickness of the amino group-containing
polymer can be selected to be of appropriate size on the support
material when the polymer is not covalently bound to the support
material.
[0029] Adequate flexibility and permeability of the amino
group-containing polymer is important so that several of the amino
groups can come into a conformation which enables the metals to be
multiply bound co-ordinately.
[0030] The high metal binding capacity of the sorbents according to
the invention or of the sorbents produced according to the
following processes according to the invention was surprising for
the inventors for the following reasons: [0031] in spite of the
almost complete filling of the pores of the support material with
the amino group-containing polymer, the pores are accessible for
the metals owing to the permeability of the polymer, as a result of
which the sorbent according to the invention has a high metal
binding capacity. This was all the more astonishing since polymer
standards from inverse size exclusion chromatography exhibit no
accessibility or permeability. This was also to be observed to over
90% even for the smallest standards with 450 Da. [0032] In contrast
to normal chromatographic sorbents and metal-binding sorbents,
which are based on the principle of surface functionalization, it
was surprisingly found through the high metal-binding property that
the present invention utilizes the entire volume of the polymer
responsible for the binding and not only the surface thereof, i.e.
the amino group-containing polymer together with the solvent
containing the metals forms a so-called hydrogel, in which the
polymer network exhibits nanoporosity. This has the effect that the
metal binding capacity is not determined only by the surface of the
support material, but rather by the volume of the polymer applied.
[0033] The high metal binding capacity of the sorbents according to
the invention or sorbents produced according to the invention is
due to the formation of chemical complexes between groups of the
amino group-containing polymer and the metals to be bound. These
groups can be the amino groups themselves, or can be residues which
have Lewis base properties, which are bound to the amino
group-containing polymer (as described below). This for example
results in the advantage of the high salt tolerance and binding
capacity in the acidic medium compared to classical ion exchangers.
[0034] In parallel to the formation of chemical complexes via which
the metals are bound, the phase still also has a very high binding
capacity for anions, e.g. sulphate, phosphate, nitrite, nitrate,
chromate, arsenate, etc.
[0035] The amino group-containing polymer on the sorbent according
to the invention is preferably a polymer which has primary and/or
secondary amino groups. It can be a polymer of the same repeating
units (polymerized monomers), but it can also be a copolymer which
preferably has simple alkene monomers or polar, inert monomers such
as vinylpyrrolidone as comonomers.
[0036] Examples of the amino group-containing polymer are the
following: polyamines, such as any polyalkylamines, e.g.
polyvinylamine and polyallylamine, polyethyleneimine, polylysine
etc. Among these, polyalkylamines are preferred, and polyvinylamine
and polyallylamine still more preferred, with polyvinylamine being
particularly preferred.
[0037] According to a preferred embodiment of the sorbent according
to the invention, the amino group-containing polymer has a degree
of crosslinking of at least 2%, based on the total number of
crosslinkable groups in the amino group-containing polymer. More
preferably, the degree of crosslinking lies in the range from 2.5
to 60%, more preferably in the range from 5 to 50% and most
preferably in the range from 10 to 40%, in each case based on the
total number of crosslinkable groups in the amino group-containing
polymer. The degree of crosslinking can be adjusted with the
appropriately desired quantity of crosslinking agent. Here it is
assumed that 100 mol. % of the crosslinking agent reacts and forms
crosslinkages. This can be verified by analytical methods such as
by MAS-NMR spectroscopy and quantitative determination of the
quantity of the crosslinking agent relative to the quantity of the
polymer used. This method is to be preferred according to the
invention. The degree of crosslinking can, however, also be
determined by IR spectroscopy based on, for example, C--O--C or
OH-vibrations using a calibration curve. Both methods are standard
analytical methods for a person skilled in the art in this field.
If the degree of crosslinking lies above the stated upper limit,
the polymer coating of the amino group-containing polymer is not
flexible enough and results in a lower metal binding capacity. If
the degree of crosslinking is below the stated lower limit, the
polymer coating is not sufficiently stable on the surface of the
porous support material.
[0038] The crosslinking agent has two, three or more functional
groups through the binding of which to the polymer the crosslinking
takes place. The crosslinking agent which is used for crosslinking
the amino group-containing polymer is preferably selected from the
group which consists of dicarboxylic acids, tricarboxylic acids,
urea, bis-epoxides or tris-epoxides, diisocyanates or
triisocyanates, and dihaloalkylene or trihaloalkylene, with
dicarboxylic acids and bis-epoxides being preferred, such as for
example terephthalic acid, biphenyldicarboxylic acid, ethylene
glycol diglycidyl ether and
1,12-bis-(5-norbornene-2,3-dicarboximido)-decanedicarboxylic acid,
with ethylene glycol diglycidyl ether and
1,12-bis-(5-norbornene-2,3-dicarboximido)-decanedicarboxylic acid
being more preferred. In one embodiment of the present invention,
the crosslinking agent is preferably a linear, conformationally
flexible molecule with a length between 4 and 20 atoms.
[0039] The preferred molecular weight of the amino group-containing
polymer of the sorbent according to the invention preferably lies
in the range from 5000 to 50,000 g/mol, which applies in particular
for the polyvinylamine used.
[0040] The sorbent according to the invention can, in a further
embodiment, also have organic residues which are bound onto the
amino group-containing polymer and have the nature of a Lewis base.
Here it is particularly preferred that the organic residue is bound
onto an amino group of the amino group-containing polymer. Also it
is particularly preferred that the amino group onto which the
organic residue is bound after the binding is a secondary amino
group, so that this also still displays sufficient Lewis basicity,
but without being sterically hindered.
[0041] In a further embodiment, the present invention also relates
to a process for the production of a sorbent, preferably a sorbent
according to the invention, which contains the following steps
(preferably in the stated order): [0042] (a) provision of a porous
support material;
[0043] (b) application of an amino group-containing polymer onto
the porous support material by a pore filling method;
[0044] (c) removal of the solvent used in the pore filling method;
(d) repetition of steps (b) and (c); and [0045] (e) crosslinking of
the amino group-containing polymer.
[0046] In the process according to the invention for the production
of a sorbent, the porous support material provided in step (a) is
one as mentioned above in connection with the sorbent according to
the invention. The preferred embodiments mentioned there apply here
to the same extent.
[0047] In step (b) of the process according to the invention, a
non-crosslinked amino group-containing polymer, as is described
above in connection with the amino group-containing polymer of the
sorbent according to the invention, is preferably used. The
preferred embodiments mentioned there apply here to the same
extent.
[0048] The pore filling method in step (b) of the application of
the amino group-containing polymer onto the porous support material
in the process according to the invention entails the advantage
compared to conventional impregnation processes that overall a
larger quantity of amino group-containing polymer can be applied
onto the porous support material, as a result of which the binding
capacity for metals is increased. This results in the aforesaid
surprising advantages.
[0049] The pore filling method is in general understood to mean a
special coating method in which a solution which contains the amino
group-containing polymer, is applied onto the porous support
material in the quantity which corresponds to the total volume of
the pores of the porous support material. Here, the total volume of
the pores of the porous support material in step (b), i.e. the
first application, is determined beforehand as stated above.
[0050] In step (c) of the process according to the invention, the
solvent used for the pore filling method is preferably removed by
drying the material at temperatures in the range from 40.degree. C.
to 90.degree. C., more preferably in the range from 50.degree. C.
to 70.degree. C. and most preferably in the range from 50.degree.
C. to 60.degree. C. During this, drying is in particular effected
at a pressure in the range from 0.01 to 1 bar, more preferably at a
pressure in the range from 0.1 to 0.5 bar.
[0051] It is an essential step of the process according to the
invention for the production of a sorbent that in a step (d) after
the drying or removal of the solvent from the first step of the
application by pore filling method, the steps (b) and (c) of the
application of an amino group-containing polymer onto the porous
support material by a pore filling method are repeated. For this,
the total volume of the pores which is available for the repeated
application of the amino group-containing polymer onto the porous
support material is determined after step (b) by differential
weighing of the wet and the dry material. In a further embodiment
of the process according to the invention, it is moreover preferred
that the steps (b) and (c) are repeated at least twice. The total
volume of the pores available for the pore filling method is also
determined by differential weighing of the wet and the dry
materials before the second repetition of steps (b) and (c). The
repetition of steps (b) and (c) preferably takes place in the
stated order.
[0052] After the steps of the application of the amino
group-containing polymer, the crosslinking of the amino
group-containing polymer takes place in a step (e), preferably by
the crosslinking agent stated in connection with the sorbent
according to the invention. All features stated above in connection
with the sorbent according to the invention with regard to the
crosslinking also apply to the production process according to the
invention.
[0053] It is further preferred that between the multiple steps of
the application of an amino group-containing polymer onto the
porous support material by a pore filling method, no crosslinking
of the amino group-containing polymer takes place.
[0054] Preferably the removal of the solvent used in the pore
filling method each time is effected by drying in a ploughshare
dryer, since this step can be markedly accelerated thereby.
[0055] In a further embodiment, in the process according to the
invention the steps (b) and (c) are repeated before the step (e)
sufficiently often that the concentration of the amino groups of
the sorbent determined after step (e) by titration is at least 600
.mu.mol/mL, more preferably at least 800 .mu.mol/mL, still more
preferably at least 1000 .mu.mol/mL and most preferably at least
1200 .mu.mol/mL, in each case based on the total volume of the
sorbent. The upper limits of the concentration of the amino groups
of the sorbent stated above in connection with the sorbent
according to the invention are also the upper limits preferred in
the process according to the invention.
[0056] In a further embodiment of the process according to the
invention, it is preferred that the ratio of the mass of the amino
group-containing polymer to the total volume of the pores of the
porous support material after step (d) is greater than or equal to
0.1 g/mL, more preferably greater than or equal to 0.125 g/mL, and
most preferably greater than or equal to 0.15 g/ml. The upper limit
of this ratio is preferably about at most 0.5 g/mL, more preferably
at most 0.4 g/mL and most preferably at most 0.3 g/mL.
[0057] In the pore filling method in step (b) of the process
according to the invention, as solvent for the amino
group-containing polymer, one in which the amino group-containing
polymer is soluble is preferably used. The concentration of the
amino group-containing polymer in the solvent used for the pore
filling method in step (b) of the process according to the
invention preferably lies in the range from 5 g/L to 200 g/L, more
preferably in the range from g/L to 180 g/L, most preferably in the
range from 30 to 160 g/L. A concentration below the stated lower
limit has the disadvantage that the steps (b) and (c) would have to
be performed too often in order to achieve the desired
concentration of the amino groups of the sorbent determined by
titration, which ensures a sufficient binding capacity for metals.
A concentration above the stated upper limit does not ensure that
the polymer can penetrate to a sufficient extent into the pores of
the porous support material.
[0058] In a further embodiment of the process according to the
invention it is preferred that in a step (f)--preferably after the
step (e)--an organic residue which has the nature of a Lewis base
is bound onto the amino group-containing polymer. Here it is
particularly preferred that the organic residue is bound onto the
amino groups of the amino group-containing polymer. It is further
preferred here that after the binding of the organic residue, the
amino groups are present as secondary amino groups, so that their
Lewis basicity is not lost and no steric hindrance to the binding
of the amino groups to the metals arises. An organic residue which
has the nature of a Lewis base is understood in particular to refer
to residues which enter into complex bonding with the metal to be
bound.
[0059] Organic residues which contain a Lewis base are for example
those which contain hetero atoms with free electron pairs, such as
N, O, P, As or S.
[0060] All preferred embodiments mentioned above in connection with
the sorbent according to the invention apply to the same extent for
the sorbent produced by the process according to the invention, or
for the components used in the process according to the
invention.
[0061] In a further embodiment, the present invention also relates
to a sorbent which is obtainable by the process according to the
invention, in particular a sorbent which is obtainable by a process
according to the invention, wherein in a step (f) an organic
residue which has the nature of a Lewis base is bound onto the
amino group-containing polymer. Such a sorbent can through the
functionalization with an organic residue also have a concentration
of the amino groups of the sorbent determined by titration of less
than the limit stated above, and is however in particular
characterized in that through the single or multiple repetition of
steps (b) and (c) in the process according to the invention, the
freely accessible pores of the support material are essentially
completely filled with the amino group-containing polymer (this is
achieved when the WAC is less than 0.5 wt. %), or the ratio of the
mass of the amino group-containing polymer to the total volume of
the porous support material after step (d) lies in the range stated
above. Such a sorbent, which has an organic residue which has the
nature of a Lewis base, is also intended to include those sorbents
which after the removal of the organic residue from the amino
group-containing polymer have a concentration of the amino groups
of the sorbent determined by titration of at least 600 .mu.mol/mL,
based on the total volume of the sorbent.
[0062] A further embodiment of the present invention relates to the
use of a sorbent for binding metals from solutions, wherein the
sorbent is either a porous support material coated with an amino
group-containing polymer, wherein the concentration of the amino
groups of the sorbent determined by titration is at least 300
.mu.mol/mL, more preferably at least 400 .mu.mol/mL, and still more
preferably 500 .mu.mol/mL, or wherein the sorbent is a sorbent
obtainable by the process according to the invention.
[0063] In other words the present invention also relates to a
process for binding metals from solutions using a sorbent, wherein
the sorbent is either a porous support material coated with an
amino group-containing polymer, wherein the concentration of the
amino groups of the sorbent determined by titration is at least 300
.mu.mol/mL, more preferably at least 400 .mu.mol/mL, and still more
preferably 500 .mu.mol/mL, or wherein the sorbent is a sorbent
obtainable by a process according to the invention.
[0064] The solutions from which metals are to be bound can
according to the invention be concentrated or dilute, aqueous or
non-aqueous, acidic, basic or neutral solutions.
[0065] The metals of the present application are preferably metals
which are present in the said solutions in ionic form or also as
metal-ligand coordination compounds in ionic form. The metals are
preferably complex-forming metals, i.e. metals which can enter into
a metal-ligand coordination bond. More preferably, the metals are
transition metals or metals of the rare earths, still more
preferably noble metals or rare earths. Quite particularly
preferably, the metals are copper, nickel and chromium.
[0066] In a further embodiment of the use according to the
invention, the solutions from which the metals are to be bound are
solutions which have a salt content of alkali metal ions of at
least 5 g/l.
[0067] Furthermore, the solutions from which the metals are to be
bound are preferably aqueous solutions, in particular also an
acidic aqueous solution, with a pH of 5, more preferably 4 and
still more preferably 3.
[0068] For binding the metals from solutions, the metal-containing
solutions are brought into contact with the sorbent according to
the invention. This can for example take place in a normal column.
At the same time, sorbents according to the invention which have
been developed for binding different metals can also be present
mixed together. This is as a rule effected through the binding of
different organic residues onto the amino group-containing
polymer.
[0069] Similarly, the contacting of the sorbent according to the
invention with the metal-containing solution can also be performed
in batch mode, i.e. without passage of the solution through a
vessel with the sorbent, but rather in the form of a suspension of
the sorbent in the solution.
[0070] The present invention will now be illustrated on the basis
of the following figures and examples, which are however only to be
regarded as by way of example:
EXAMPLES SECTION
Analytical Methods:
[0071] Determination of the concentration of the amino groups of a
sorbent by breakthrough measurement with 4-toluenesulphonic acid
(titration analysis):
[0072] The dynamic anion exchange capacity is determined with a
column of the stationary phase to be tested. For this, firstly all
exchangeable anions in the column are exchanged against
trifluoroacetate. Then the column is rinsed with an aqueous reagent
solution of toluene-4-sulphonic acid until this solution emerges
again in the same concentration at the end of the column
(breakthrough). From the concentration of the toluene-4-sulphonic
acid solution, its flow rate and the area of the breakthrough in
the chromatogram, the quantity of toluene-4-sulphonic acid bound by
the column is calculated. The quantity of toluene-4-sulphonic acid
thus determined gives the concentration of the amino groups of the
sorbent.
[0073] The dynamic anion exchange capacity for toluene-4-sulphonic
acid in water is related to the phase volume and reported in mmol
per litre (mM/L).
Example 1: Production of a Sorbent According to the Invention
[0074] 200 g of a sulphonated polystyrene/divinylbenzene support
material (average pore size 30 nm) are weighed into a vessel. This
material has a pore volume determined from the WAC of 1.48 mL/g. In
the first coating the pore volume should be 95% filled. The polymer
solution for the coating is prepared. 165.3 g of a polyvinylamine
solution (solids content 12.1 wt. %) are diluted with 108 g water.
The pH of the solution is adjusted to 9.5 with 7 ml conc.
hydrochloric acid. The polymer solution is added to the support and
mixed for 3 hrs on the overhead shaker. Next, the coated support is
dried for 48 hrs at 50.degree. C. in the vacuum drying cabinet at
25 mBar. The material has lost 197.7 g water through the drying.
The material is coated for the second time. For this, 165.0 g
polyvinylamine solution (solids content 12.1 wt. %) are adjusted to
a pH of 9.5 with 6.8 mL conc. HCl and diluted with 20 g water. The
polymer solution is added to the support and mixed for 3 hrs on the
overhead shaker. Next, the coated support is dried for 48 hrs at
50.degree. C. in the vacuum drying cabinet at 25 mBar. The material
has lost 181.2 g water through the drying. The material is coated
for the third time. For this, 165.2 g polyvinylamine solution
(solids content 12.1%) are adjusted to a pH of 9.5 with 7.1 mL
conc. HCl and diluted with 5 g water. The polymer solution is added
to the support and mixed for 3 hrs on the overhead shaker. The
phase is then dried to constant weight in the vacuum drying cabinet
at 50.degree. C. and 25 mBar.
[0075] The material was coated in 3 steps with a total of 0.20 g
PVA per mL pore volume.
[0076] The dried material was suspended in 1.5 L isopropanol in a
double-jacket reactor and crosslinked with 24.26 g ethylene
diglycol diglycidyl ether at 55.degree. C. within 6 hrs.
[0077] The coated material is washed with the following solvents:
600 mL isopropanol, 3600 mL 0.1 M HCl, 1800 mL water, 1800 mL 1 M
NaOH, 1800 mL water and 1800 mL methanol.
[0078] The material is then dried. Yield 275 g dried material.
[0079] Analysis: the concentration of the amino groups determined
by titration is 963 .mu.mol/mL.
Comparison Example 1: Production of a Conventional Sorbent
[0080] The conventional sorbent is a silica gel modified with
2-aminoethyl sulphide ethyl
((Si)--CH.sub.2--CH.sub.2--S--CH.sub.2--CH.sub.2--NH.sub.2) with a
particle size of >45 .mu.m (Manufacturer Phosphonics, Supplier
Sigma-Aldrich, Catalogue number: 743453-10G; 0.8-1.3 mmol/g
loading).
[0081] The modification can be effected by reaction of silica gel
with 3-mercapto-propyl-trimethoxysilane and subsequent reaction
with ethylimine.
Example 2: Use of the Sorbents Produced According to Example 1 and
Comparison Example 1 for Binding Copper from Aqueous Solutions
[0082] For plotting isotherms in FIGS. 1 and 2, the following
procedure was used:
[0083] 10 samples each of approx. 100 mg of the sorbent are
precisely weighed out and in each case incubated with different
aqueous Cu-II solutions (as CuSO.sub.4) of different concentration
for at least 1.5 hrs. The sorbent is filtered off and the Cu-II
concentration in solution determined photometrically. From the
remaining concentration of copper, the quantity of copper bound is
calculated and the isotherms generated.
[0084] From the comparison of the isotherms in FIGS. 1 and 2, it
can be seen that the sorbent according to the invention has a
considerably higher binding capacity than the conventional sorbent.
From the approximated rectangular isotherms for the sorbent
according to the invention it can be seen that this shows very
strong bonding without actual establishment of equilibrium. This
also allows the almost complete removal of heavy metals from very
dilute solutions.
Example 3: Use of the Sorbent Produced According to Example 1 for
Binding the Three Transition Metals Nickel, Copper and Chromium
from a Solution
[0085] In each case 10 samples of a defined quantity of the sorbent
are precisely weighed out and in each case incubated with different
aqueous metal solutions of different concentration for at least 1.5
hrs. The sorbent is filtered off and the metal concentration in
solution determined photometrically or with a metal determination
method according to Hach-Lange (preferably photometrically). From
the remaining concentration of metal, the quantity of metal bound
is calculated and the isotherms generated.
[0086] From FIG. 3 it can be seen that the sorbent according to the
invention binds the metals nickel (.about.70 mg/g sorbent), copper
(.about.120 mg/g sorbent) and chromium (.about.80 mg/g sorbent) to
a high degree. The same could also be shown for solutions with the
metals palladium, lead and iridium.
Example 4: Use of the Sorbent Produced According to Example 1 for
Binding Metals from Solutions with a High Salt Content
[0087] 5 samples of approx. 100 mg of the sorbent are precisely
weighed out and each incubated for at least 0.5 hrs with a solution
of Cu (as CuSO4*5H2O=50 mg/ml water), which contain 0 M NaCl, 0.01
M NaCl, 0.1 M NaCl, 0.5 M NaCl and 1 M NaCl respectively. Next, the
sorbent is filtered off and the copper concentration in the
filtrate determined photometrically. From the remaining
concentration of metal, the quantity of copper bound is calculated
and the isotherms generated.
[0088] As can be seen from FIG. 4, even at concentrations of up to
1 M common salt, the binding capacity of copper is >100 mg Cu/g
sorbent. This shows that a non-ionic binding mechanism is involved,
which thus markedly differs from ion exchangers "customary in the
trade".
[0089] There is no competition for binding sites of copper with
sodium, which is not complexed. The binding capacity for copper is
thus maintained.
[0090] This property allows the use of the phase in the treatment
of drinking, surface, pit, and waste waters, seawater desalination
plants, chloralkali electrolysis etc. in which alkali and alkaline
earth metals ubiquitously occurring and present in large excess
must not interfere.
Example 5: Binding Rate of a Sorbent Produced According to Example
1
[0091] Samples each with approx. 100 mg of the phase are precisely
weighed out and incubated with a Cu solution (as CuSO4*5H2O=50
mg/ml water) for the stated period. Next, the sorbent is filtered
off and the copper concentration in the filtrate determined
photometrically. From the remaining concentration of metal the
quantity of copper bound is calculated.
[0092] FIGS. 5 and 6 show the binding of copper from solutions
against time. After about 90 minutes, all binding sites of the
sorbent are occupied by copper. No change in the concentration is
to be observed even after 48 hours.
Example 6: Reusability of the Sorbent Produced According to Example
1
[0093] 1 g of the sorbent from Example 1 is weighed out and treated
as follows: [0094] 1. Rinsing with 1 M NaOH (3.times.5 ml) [0095]
2. water (3.times.5 ml rinsed). [0096] 3. Addition of 50 ml Cu (as
CuSO.sub.4*5H.sub.2O, 50 mg/ml) [0097] 4. Incubation for 90 mins
[0098] 5. Filtration [0099] 6. Determination of the copper
concentration in the filtrate (photometrically) and calculation of
the quantity of copper bound [0100] 7. Repetition of the
procedure
[0101] As can be seen from FIG. 7, the binding capacity of copper
remains unimpaired after 10 cycles of regeneration and reuse of the
sorbent after 10 cycles (with the exception of cycles 5 and 6) even
with treatment with 5 M HCL and 1 M NaOH.
Example 7: Comparison of Multiply Coated Sorbents with a Singly
Coated Sorbent
Production of a Singly Coated Sorbent on a Silica Support:
[0102] 100 g silica gel AGC D-50-120A (average pore size 12 nm) are
weighed into a vessel. This material has a pore volume determined
from the WAC of 1.12 mL/g. The polymer solution for the coating is
prepared. 79.6 g of a polyvinylamine solution (solids content 11.3
wt. %) are diluted with 20 g water. The pH of the solution is
adjusted to 9.5 with 3 ml conc. hydrochloric acid. The polymer
solution is added to the support and mixed for 6 hrs on a screening
machine. Next, the coated support is dried for 48 hrs at 50.degree.
C. in the vacuum drying cabinet at 25 mbar.
[0103] The material was coated with 0.08 g PVA per mL pore
volume.
[0104] The dried material was suspended in 0.5 L isopropanol in a
double-jacket reactor and crosslinked with 3.64 g ethylene diglycol
diglycidyl ether at 55.degree. C. within 6 hrs.
[0105] The coated material is washed with the following solvents:
400 mL isopropanol, 1200 mL 0.1 M HCl, 400 mL water, 800 mL 0.5 M
triethylamine in water, 600 mL water and 600 mL methanol.
[0106] The material is then dried. Yield 108.0 g dried
material.
[0107] Analysis: the concentration of the amino groups determined
by titration is 593 .mu.mol/mL.
Production of a Doubly Coated Sorbent on a Silica Support:
[0108] 250 g silica gel AGC D-50-120A (average pore size 12 nm) are
weighed into a vessel. This material has a pore volume determined
from the WAC of 1.12 mL/g. The polymer solution for the coating is
prepared. 200 g of a polyvinylamine solution (solids content 11.3
wt. %) are diluted with 60 g water. The pH of the solution is
adjusted to 9.5 with 7.5 ml conc. hydrochloric acid. The polymer
solution is added to the support and mixed by vibration for 6 hrs
on the screening machine. Next, the coated support is dried for 48
hrs at 50.degree. C. in the vacuum drying cabinet at 25 mbar. The
material has lost 230 g water through the drying. The material is
coated for the second time. For this, 200 g polyvinylamine solution
(solids content 11.3 wt. %) are adjusted to a pH of 9.5 with 6.8 mL
conc. HCl and diluted with 23 g water. The polymer solution is
added to the support and again mixed by vibration for 6 hrs on the
screening machine. Next, the coated support is dried for 48 hrs at
50.degree. C. in the vacuum drying cabinet at 25 mbar.
[0109] The material was coated with 0.16 g PVA per mL pore
volume.
[0110] The dried material was suspended in 1.5 L isopropanol in a
double-jacket reactor and crosslinked with 18.2 g ethylene diglycol
diglycidyl ether at 55.degree. C. within 6 hrs.
[0111] The coated material is washed with the following solvents:
1000 mL isopropanol, 3000 mL 0.1 M HCl, 1000 mL water, 2000 mL 0.5
M triethylamine in water, 1500 mL water and 1500 mL methanol.
[0112] The material is then dried. Yield 308 g dried material.
[0113] Analysis: the concentration of the amino groups determined
by titration is 1254 .mu.mol/mL.
Production of a Triply Coated Sorbent on a Silica Support:
[0114] 250 g silica gel AGC D-50-120A (average pore size 12 nm) are
weighed into a vessel. This material has a pore volume determined
from the WAC of 1.12 mL/g. The polymer solution for the coating is
prepared. 199 g of a polyvinylamine solution (solids content 11.3
wt. %) are diluted with 60 g water. The pH of the solution is
adjusted to 9.5 with 7.6 ml conc. hydrochloric acid. The polymer
solution is added to the support and mixed by vibration for 6 hrs
on the screening machine. Next, the coated support is dried for 48
hrs at 50.degree. C. in the vacuum drying cabinet at 25 mbar. The
material has lost 231 g water through the drying. The material is
coated for the second time. For this, 200 g polyvinylamine solution
(solids content 11.3 wt. %) are adjusted to a pH of 9.5 with 7.0 mL
conc. HCl and diluted with 24 g water. The polymer solution is
added to the support and again mixed by vibration for 6 hrs on the
screening machine. Next, the coated support is dried for 48 hrs at
50.degree. C. in the vacuum drying cabinet at 25 mbar. The material
has lost 210 g water through the drying. The material is coated for
the third time. For this, 199 g polyvinylamine solution (solids
content 11.3 wt. %) are adjusted to a pH of 9.5 with 7.0 mL conc.
HCl and diluted with 4 g water. The polymer solution is added to
the support and again mixed by vibration for 6 hrs on the screening
machine. Next, the coated support is dried for 48 hrs at 50.degree.
C. in the vacuum drying cabinet at 25 mbar.
[0115] The material was coated with 0.24 g PVA per mL pore
volume.
[0116] The dried material was suspended in 1.5 L isopropanol in a
double-jacket reactor and crosslinked with 27.3 g ethylene diglycol
diglycidyl ether at 55.degree. C. within 6 hrs.
[0117] The coated material is washed with the following solvents:
1000 mL isopropanol, 3000 mL 0.1 M HCl, 1000 mL water, 2000 mL 0.5
M triethylamine in water, 1500 mL water and 1500 mL methanol.
[0118] The material is then dried. Yield 330 g dried material.
[0119] Analysis: the concentration of the amino groups determined
by titration is 1818 .mu.mol/mL.
[0120] FIG. 8 shows unambiguously that the binding capacity with
the doubly and the triply coated sorbent increases drastically
compared to the singly coated sorbent.
Comparison Example 2: Production of a Sorbent According to Example
2 of DE 10 2011 107 197 A1
[0121] As the base for the sorbent, Amberchrom CG1000S from Rohm
& Haas is used. This is sulphonated as follows: for this, 165
mL conc. H.sub.2SO.sub.4 are placed in a temperature-controllable
250 mL reactor. 30.0 g of the support material are added to the
sulphuric acid and the weighing bottle then rinsed three times in
each case with 20 mL conc. sulphuric acid. After the addition of
the support material, the suspension is stirred and maintained at
80.degree. C. After 3 hrs reaction time, the suspension is
discharged from the reactor and distributed into two 150 mL
syringes. The sulphuric acid is removed under suction and the phase
successively rinsed with 200 mL diluted (62%) sulphuric acid, 125
mL water, 175 mL methanol, 125 mL water and finally with 175 mL
methanol. The phase is suction dried and then dried at 50.degree.
C. under vacuum. The water absorption capacity or the pore volume
of the resulting sulphonated polystyrene is determined by weighing
the dried, sulphonated polystyrene, treating with the same volume
of water and then centrifuging off excess water. The water present
in the pores remains in place during this.
[0122] For the coating of the polystyrene, an aqueous
polyvinylamine solution is prepared, which consists of
polyvinylamine with an average molar weight of 35,000 g/mol. The pH
is adjusted to 9.5. The quantity of polyvinylamine here is 15% of
the polystyrene to be coated, and the volume of the solution is 95%
of the determined pore volume of the polystyrene. The
polyvinylamine solution together with the polystyrene is placed in
a firmly closed PE bottle and shaken at high frequency for 6 hours
on a screening shaker. During this, attention must be paid to
adequate mixing. After the procedure, the polyvinylamine solution
has worked itself into the pores of the polystyrene. The
polystyrene is then dried to constant weight at 50.degree. C. in
the vacuum drying cabinet.
[0123] For the crosslinking of the polyvinylamine, the coated
polystyrene is taken up in three times the volume of isopropanol
and treated with 5% diethylene glycol diglycidyl ether, based on
the amino group count of the polyvinylamine. The reaction mixture
is stirred for six hours in the reactor at 55.degree. C. Next, it
is transferred onto a glass suction filter and rinsed with 2 bed
volumes isopropanol, 3 bed volumes 0.5 M TFA solution, 2 bed
volumes water, 4 bed volumes 1 M sodium hydroxide solution and
finally 8 bed volumes water.
[0124] Analysis: the concentration of the amino groups determined
by titration is 265 .mu.mol/mL.
* * * * *