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35,888,799
Patented May 7, 1963
2
have been used to remove cations from solution by ex
3,088,799
METAL EXTRACTIUN PROCESS
changing them for existing cations of the resin. The
The present invention relates to a particular class of
solid chelating agents and their use in the selective ex
traction of a particular class of heavy metals from solu
rate of ?ow through a resin column is very slow thereby
adding to the time required for removal of the metal.
Moreover, the capacities of these resins are quite lim
ited, i.e., of the order of 5 to 20% ‘of the resin weight.
The ion-exchange resins are not at all selective, for the
most part they pick up the ion of the greatest concentra
tion at a given valence level. In fact, they are useless
for the removal of metals present in hard water or pres
ent in solutions of strong salts.
tions. More particularly, the present invention pertains
Thus, to selectively extract one ion from a solution con
Charles A. Fetscher, Short Hills, N.J., assignor to Nopco
Chemical Company, Harrison, N.J., a corporation of
New Jersey
No Drawing. Filed May 25, 1959, Ser. No. 815,246
14 Claims. ((31. 23-145)
to a novel and superior process of selectively extracting
heavy metals from solutions containing same by means
taining several is a very desirable operation and one that
has been very di?icult to achieve.
of high molecular weight organic polymers referred to 15
Accordingly, it is an object of the present invention to
selectively remove and recover in a novel manner sub
hereinafter as polyamidoximes.
The problem of selectively extracting as well as recov
stantially all of one, several or all of a selected group of
erin-g heavy metal ions is of extreme importance. For
heavy metal ions which are present in solutions contain
instance, in the matter of river pollution by industrial
ing the same plus other non-recoverable ions.
wastes, due to public and governmental pressure, indus 20
Another object is to selectively remove and recover
tries must remove toxic waste components from plant ef—
substantially all of one or several of a selected group of
?uents. Among the important problems are toxic con
heavy metal ions from solutions containing mixtures of
centrations of heavy metals such as copper. Moreover,
heavy metal ions, all of said metals being capable of re
due to increased use of ?ssionable materials, increased
covery.
quantities of highly dangerous radioactive materials are 25
A further object is to provide for a continuous proc
created which must be completely recovered for special
disposal. Some of these dangerous radioactive species
are heavy metal cations.
In many instances, besides the problem of removing
metals from industrial wastes prior to disposal, these same
metals are undesirable during the operations per se.
Some metallic contaminants interfere in ?otation proc
ess for extracting one or a mixture of a selected group
of heavy metal ions from solutions containing same which
solutions also contain other non-recoverable ions as well
as to provide for a continuous process for extracting one
or several of a selected group of heavy metal ions from
solutions containing a mixture of heavy metal ions, all
of said metals being capable of recovery.
Another object is to selectively remove and recover said
Metals, par
ticularly copper and iron, are undesirable in steam gen 35 heavy metal ions when they are present in minute quan
erators, condensers and other equipment through which
tities, i.e., of the order of 10 to 10*“4 ppm. in solution
water is passed. Many processes such as textile dyeing,
in an economical and substantially complete manner.
paper making, etc., require careful regulation and pro
Still another object is to selectively remove and recover
tection against metal contaminants. The deactivation of
said heavy metal ions from non-aqueous solutions.
A still further object is to substantially completely elute
metallic contamination which would interfere with the 40
esses and must be removed or deactivated.
process contemplated is the only important commercial
use of chelating agents today.
In many industrial processes, loss of metals represents
from a class of materials chelated with a mixture of
said selected group of heavy metal ions, one or several
of said mixture ‘of heavy metal ions.
Other objects are to provide for selective extraction
sufficient recovery of precious metals from plating baths 45 and elution processes making use of a relatively inex
adds greatly to cost. Similarly, in precious metal re?n
pensive solid chelating agent that is easy to adapt to a
ing per se, it is extremely desirable to cut down loss of
variety of processes and in which said agent is normally
metal through re?nery wastes. In fact, in any re?ning
capable of giving up the removed metallic ions for their
process, recovery of metals from mill effluents and other
recovery and capable of being regenerated in a direct
aqueous wastes would greatly reduce overall cost of op 50 manner.
eration. In most ?otation processes, dissolved metallic
Other objects will become apparent from the detailed
a large economic loss.
values represent a loss.
For instance, non-recovery or in
The heavy metal ores are very
description given herein. It is intended, however, that
limitedly soluble in water and dissolved concentrations
the detailed description and speci?c examples do not limit
in the tailings Water will seldom exceed possibly 100
the invention, but merely indicate preferred embodiments
ppm. No process of the prior art has been able to 55 thereof since various changes and modi?cations within
economically recover heavy metals from such low con
the scope of the invention will become apparent to those
centrations in solutions which are also normally rich in
skilled in the art.
sodium and calcium. Although the concentration of the
I have discovered that solid polyamidoximes are very
valuable metal in the tailings water will be very low, the
selective chelating agents. They will form complexes
volume of water used by even a small ?otation mill is
with a selected group of heavy metals of atomic weight
enormous and the total metal value lost is important.
greater‘ than about 5 0 selected from the periodic chart of
In the recovery of uranium, the problem is very im
the elements while they do not form complexes with other
portant. Uranium is relatively valuable, it is found in
metals such as lighter metals as sodium, calcium and alu
relatively low concentrations and its salts are fairly sol
uble. A very considerable percent of the uranium is 65 minum. This selectivity is demonstrated when an ex
traction is carried out upon a solution containing mix
lost in the tailings of an ore bene?ciation plant. My proc
ess, when applied to uranium removal, will substantially
prevent this loss.
Many innovations have been introduced and tried in
order to increase the recovery of heavy metals particular
ly from dilute aqueous media and have met with vary
ing degrees ‘of success. For instance, ion exchange resins
tures of both the above heavy metal ions and the com
mon lighter ions. IMoreover, I have also discovered that
I am able to selectively extract one or several heavy metals
from a solution containing a mixture of heavy metal
ions all of which are capable of recovery. Furthermore,
having extracted a mixture of said heavy metal ions, I
3,088,799
3
may also selectively elute from the complex, one or sev
eral of said ions.
These discoveries can be accomplished by bringing
solutions containing heavy metal ions as described above
into contact with a solid chelating agent comprising a
high molecular weight organic polymer containing ami
doxime substituents, referred to as hereinafter as a poly
amidoxirne.
Substantially complete removal of the de
4
plexes at the expense of other complexes, and the forma
tion from amazingly low concentrations of the metal ion.
It have discovered that the polyvalent metals which
may be selectively removed and recovered from solutions
containing same are a number of those ions of heavy
metals of atomic weight above about 50 which are set
forth in the periodic chart of the elements. The solid
polyamidoximes are particularly effective with polyvalent
heavy metals which form colored ions in solution. Fur
sired metal ion or ions from the liquid media is accom
plished by such a procedure while other ions, even those 10 thermore, I have discovered that solid polyamidoximes
which are capable of removal by my process are unaf
complex with and extract the metal ions from very dilute
fected. During contact between the solution and the
solutions, e.g., as low as concentrations of 10"5 to 10*“.
chelating agent, the amidoxime groups and the metal ions
Table I lists the metals set forth in the periodic chart of
react to form a complex thereby withdrawing the ions
the elements along with their approximate pH values for
from solution. The ions can be removed from the com 15 their extraction which I have found may be selectively
plex and recovered if desired. Also, in most instances,
extracted and recovered, i.e., one or several, from solu
the chelating agent is simultaneously regenerated during
tions containing same. I do not specify a maximum pH
the removal of the cations. In my process, the solid
limit since extraction may be accomplished under alka
chelating agents, as will be demonstrated hereinafter,
line conditions so long as the ion remains in solution.
do not merely deactivate the metal, they selectively re
In the case of gold, this would allow for extraction up to
move it, thus both the metal and the chelating agent are
a pH of about 7 since at high pH’s the gold will normally
recovered and the chelating agent can be reused again and
precipitate out of solution. If there are present in solu
again. The soluble chelating agents of commerce, e.g.,
ethylene diamine tetra acetic acid and its analogues would
be extremely ditlicult to recover and are seldom, if ever,
reused.
Amidoximes as chemical entities have long been known.
tion two or more metals which are capable of removal and
if only one is to be removed, the pH of the metal to be
removed must be at or above the pH given in Table I
as well as below the minimum pH of the metal remaining
behind. Also, one or several of these metals may be
eluted or freed from the polyamidoxime which has been
chelated with several of the metals. Of course, if a
and a few cations; however, they have been studied very 30 polyamidoxime which is chelated is to be eluted, then
Ley and Kraift, Berichte 40, 697 (1907), mention the col
ored inner salts formed by relatively simple amidoximes
little.
Probably because of the similarity of their struc
ture to the very unstable amidines (amidoximes are also
called hydroxyarnidines), the belief that they are quite
unstable persists (see Sidgwick, Organic Chemistry of
these same pH values are controlling, i.e., they represent,
with the exception of the noble metals, an approximate
value at which the particular metal may be separated
from its complex. However, in practice it is preferable
Nitrogen, 1937, p. 201). Contrary to such prior belief, 35 to elute at a pH appreciably below the minimum pH
polyamidoximes are quite stable, i.e., they are not hy
value for chelation. Table I discloses the metals for
drolyzed or decomposed by cold dilute acid or alkali
selective extraction and selective elution (except, of course,
(from pH below 1 to about 13) in any reasonable time.
the noble metals). However, it is understood that these
I use the expression “solid chelating agents” to mean
chelating agents which function without being dissolved.
The fact that these polyamidoximes or any such solid
chelating agent is able to extract from a solution and form
extremely stable complexes with particular heavy metals
is distinctly surprising. Solid chelating agents have been
metals when in their polyvalent states may exist in sev
eral ionic forms, of which, the following are exemplary:
Simplex cation _________ _. Cu+2.
Complex cation ________ _. U02”.
Complex anion ________ __
little studied or considered by experts in this ?eld of chem
RHCH; [U02(N03)3l-1;
istry because they appear to have considerable handicap.
They cannot saturate the coordination sphere of a heavy
metal because of their limited mobility, although it may
Hydrated or ammoni
ated ion ____________ __ Cu(NH3)4+2.
happen to a limited degree under some special conditions.
The reason is that most heavy metals show coordination
numbers of six, a few have values of four and a few have
eight. Considering coordination numbers of six as typical
and realizing that the values of four and eight represent
only differences in degree, three bidentate chelating en
tities are required to ?ll the coordination sphere of the
heavy metal ion. The amidoxime moiety per se is biden
tate although, of course, the polymer molecule as a whole
is multidentate. However, the chelating groups on the
polymer are randomly separated, and it is most improl -
able that the relatively rigid molecules of the solid can
curl and encompass the metallic ion in order to saturate
all of its coordination sphere. Thus, solid bidentate che
lating agents can in general occupy only two sites in the
coordination sphere of the metal ion. It is true that un
saturated complexes are known; however, they are gen
erally assumed to be considerably less stable than com
plexes in which one or several molecules of the chelating
agent completely saturate the coordination sphere of the
metal ion and which saturation tends to form whenever
possible. Hence, it is surprising that these solid poly
amidoxirnes, which incompletely saturate the coordination
sphere of the metal, form such stable complexes with
them. The stability of these complexes is demonstrated
by their formation at very low pH, the inability to dis
rupt the gold, platinum and palladium complexes with
concentrated mineral acids, the formation of these com
AuCl4_1; PdCl4_2; PtCl?r4;
TABLE I
Metal:
pH (minimum value for
extraction: maximum value
for elution)
Plutonium
_______________________ _ _
<1
Gold ____________________________ __
<1
Platinum ________________________ __
<1
Palladium _______________________ __
<1
Rhodium ________________________ __ About 1.0
Iron ____________________________ __ About 1.5
Thallium ________________________ __ About 1.5
Vanadium _______________________ __ About 1.5
Uranium ________________________ __ About 2.0
Ruthenium _______________________ __ About 2.0
Copper __________________________ __ About 3.5
Nickel ___________________________ __ About 4.0
Cobalt __________________________ __ About 4.0
Chromium _______________________ __ About 4.0
By the pH “<1” is meant acidic pH’s which are be
low a pH of 1 and which are usually not accurately meas
urable on pH indicators which generally are accurate
down to a pH of about 1.
In the case of complex ions, it is probable that in most
instances only the metallic element is incorporated in
the amidoxime complex and that the dissociation equilib
rium of the complex ion supplies enough of the simple
3,088,799
5
cation to exceed the concentration in equilibrium with
the amidoxime. Thus, I believe, the equilibrium
and in view of the fact that only partial saturation of the
coordination spheres of certain ions with the solid poly
amidoximes is achieved, my discovery of the selective ex
traction and elution under speci?ed conditions of pH
"is far’ to the left normally but the tiny concentration of
was most unexpected.
cationic gold is more than can exist in equilibrium with
the amidoxime. It is therefore consumed and the dis
sociation of the chlorauric ion goes to completion. What
be expected, i.e., no chelation would be expected due to
the incomplete saturation of the coordination spheres of
ever the mechanism, I can selectively extract these metals
Also, possibly, one would expect solid polyamidoximes
Ordinarily no extraction would
the metals or due to interference by one ion with another.
equally well from solutions in which they are part of 10 to behave as ion exchangers and chelate any ion of the
proper charge but never as a selective chelating agent
complex anions ‘or complex cations or from solutions in
because a chelating agent normally encloses the metal
which they are simple cations. In fact, I have found that
ion, i.e., the metal is nested within the functioning groups
solid polyamidoximes selectively recover uranium about
of one or several of the chelating molecules. Hence, the
as well from solutions rich in sulfate ion in which the
uranium is present as the anionic complex
15 size and character of the ion are critical and the chelat
ing agent is speci?c to a limited number of ions. But
as explained previously, the solid polyamidoximes can
as from solutions of uranyl acetate wherein uranium is
not encircle the ion and thus it would be expected to
accept indiscriminately any ion of the proper charge as
presumably present as the uranyl ion, UO2+2. Poly
amidoximes also extract uranium from strong sodium 20 in the case of ion exchangers.
carbonate solutions wherein the uranium is complexed
Indeed, the list of metal ions of Table I which may be
with carbonate. Such solutions are frequently used to
selectively extracted from each other and from those re
maining metals of the periodic chart of the elements
remove uranium from ion-exchange resins.
elicits no basis for predicting the success of the present in
Furthermore, I have found that the metals of Table
I may be selectively extracted singly or together from 25 vention. I am aware of prior work set forth in Belgian
the remaining metals of the periodic chart of the ele
Patent No. 541,496 in which a polyamidoxime was
ments.
The following is a list of some of the metals
treated with a warm dilute ferric chloride solution there
which when in solution as ions do not form complexes
by removing the ferric ions from the solution (Example
with solid polyamidoximes.
18). However, even from a study of this procedure, my
This list is exemplary of
the remaining metals (including amphoteric metals)
30 discovery of selective extraction of one or several ions
which are set ‘forth in the periodic chart of the elements
from a plurality thereof was not at all obvious.
and which are non-chelatable with solid polyamidoximes.
luminum
Antimony
Arsenic
Magnesium
Manganese
Mercury
.B arium
Neodymium
Beryllium
Bismuth
Potassium
Praseodymium
Boron
Rubidium
Cadmium
Samarium
Calcium
Cerium
‘Cesium
Silver
Sodium
Strontium
Dysprosium
Terbium
Erbium
Thorium
Europium
Thulium
Gadolinium
Halfnium
Tin
Titanium
Holmium
Tungsten
Lanthanum
Lead
Lithium
Lutetium
Ytterbium
Yttrium
Zinc
Zirconium
Thus, any of the metals appearing in Table I when in
solution either alone or in admixture with each other
may be readily separated as a group or from each other
when in the presence of one or more of the remaining
metals of the periodic chart of the elements which I have
found do not complex with the solid polyamidoximes.
While it is possible that some of these remaining metals
in the periodic chart of the elements, i.e., other than
those metals set forth in Table I, when in an uncommon
state or over a narrow pH range may complex with a
solid polyamidoxime, such chelation has not been ob
served under the wide range of conditions which I have
tried.
Hence, these remaining metals of the periodic
chart of the elements can be considered non-chelatable in
general. However, the fact that not all metals, in fact,
GENERAL CONSIDERATIONS OF SELECTIVE
EXTRACTION AND RECOVERY
35
As stated before, I have discovered that the various
metals listed in Table I, when in solution in the form of
cations or complex cations or complex anions will form
complexes with the solid polyamidoximes which vary
in their stability to acids.
It is this difference in the
40 stability of the various complexes which makes it possi
ble to separate the various metals of Table I when in
solution from each other and from solutions also con
taining the remaining metals of the periodic chart of the
elements when also in solution.
In general, the metals in the solution are ascertained
along with the metals, one or several, which are to be
removed. The pH of the solution is also ascertained
and adjusted, if necessary, so that it is not less than or
preferably above, the value set forth in Table I for the
particular metal to be removed. In this manner, one
or several metals may be removed, i.e., all metals of
Table I which are present in solution and whose minimum
pH’s for extraction lie at or below the pH of the solu
tion. ‘If one of several metals is to be removed, then
as stated before, the pH of the solution must be at or
above the minimum pH of the metal to be removed as
set forth in Table I as Well as below the minimum pH
of the metal remaining behind. When a noble metal is
present, it will be extracted at any pH since the minimum
value for extraction is <1. Where solutions contain
metals other than those set forth in Table I, the pH as
regards these need not be taken into account since they
are not chelated. In other words, the pH considera
tions are directed to the optimum values for removing
the metal or metals of Table I which may be present.
Of course, if the pH is too high, the non-chelatable metals
may precipitate out of solution thereby promoting the
possibility of occlusion in the polyamidoxime which is
not even all heavy metals are extracted by my process is 70 not desired.
When a polyamidoxime is treated with acid so that the
itself a very advantageous feature of my process. For
metal may be recovered and the polyamidoxime is re
instance, this makes possible valuable separations and
generated, the pH should be below the pH value set
puri?cations such as gold from lead or iron from barium
forth in Table I for the metal. If one of several metals
which are normally very di?icult to achieve.
Thus, in view of the history of amidoxime complexes 75 is to be freed from its complex with the polyamidoxime,
3,088,799
'7
the pH for the metal to be freed should be below the
value set forth in Table I as well as above the values
set forth in Table I for the metals which are not freed
from the complex. As pointed out previously, the noble
metals are not eluted from their complex with the poly
amidoxime by acid treatment.
For example, the solid polyamidoximes can separate
the noble metals, i.e., gold, platinum and palladium, when
in solution from all other metals which are also present
in solution by forming chelates with their ions in the
presence of strongly acid solutions. Under such strongly
acid conditions, i.e., at a pH below 1, the remaining
metal ions of Table I as well as the remaining ions of
the periodic chart of the elements will not form a com
plex with the solid polyamidoxime. Again, at any higher
pH, gold, platinum and palladium as well as a number of
the other metals in Table I when in solution will com
8
tions. They are far more selective than are ion exchange
resins and far more useful and economical in operation
than either water soluble or oil soluble chelating agents.
Water soluble chelating agents are obviously useless for
the recovery or removal of metals from aqueous solu
tions since no economical separation from the water is
possible. ‘Oil soluble chelating agents do function, but
the separation of two liquid layers, especially in the pres
ence of the soap like polar-nonpolar complex which is
formed is far more complicated and troublesome than
?ltering out a granular resin or lifting out of solution a
?brous polyamidoxime. There is also a very considerable
di?erence in potential capacity. A chelating group is,
of course, polar and to make the molecule oil soluble,
the chelating group is attached to and diluted by a large
oil solubilizing radical. This means that oil soluble che
lators necessarily have low capacity based upon weight.
The resinous or ?brous chelators described herein do not
plex with the polyamidoxime so long as the pH of the
solution is above the minimum value set forth for the
need this dilution and therefore can have very high ca
metal (other than the noble metals) in Table I. In this 20 pacity compared to these oil soluble chelators.
instance, if desired, these other metals can be stripped
Moreover, most of the heavy metal ions considered
from the polyamidoxime complex by use of a strong
herein have a coordination number of six and therefore
mineral acid, e.g., a 5% by weight aqueous solution of
will combine with three bidentate chelate groups when
hydrochloric acid.
The noble metals are not removed
by the acid, but remain complexed with the polyamidox
ime thereby becoming separated from the other ions by
a process of elution. The gold, however, may be released
by treatment with sodium or potassium cyanide or thio—
urea in strong acid solution. Although platinum and
palladium cannot be eluted from their chelate with the
solid polyamidoxime, they still may be advantageously
recovered from solutions by formation of the chelate
complex. ‘In view of their high monetary worth, the
destruction of the polyamidoxime to recover these metals
is justi?ed.
possible as in the case of a water or oil soluble chelat
ing agent which is highly mobile. Hence, this factor
contributes to a low capacity due to the fait accompli of
complete saturation with these soluble chelators. On
the other hand, the solid polyamidoximes chelators can
only and essentially do form only a one to one com
plex with the heavy metal ion as described previously
herein. Hence, even considering an equal number of
identical bidentate chelating groups, the solid polyami
doximes have three times the capacity of an oil or water
35 soluble chelator of the same functional group for an ion
having a coordination number of six. Furthermore, by
Similarly, iron can be separated from all other com
their very nature, i.e., their viscosity, their emulsifying
mon metals. Its complex with the polyamidoxime is
tendencies and their cost, oil soluble chelators are used
formed above about pH 1.5 and it is well extracted be
in dilute oil solutions containing 1% to 5% by weight
tween about 1.5 to 2.0. Only iron and the noble metals
40 of active material. The solid chelator of my process is
will form a complex in this pH range. Iron is then re
used as is, i.e., 100% active.
moved from the polyarnidoxime by treatment with a 5%
HCl or similar acid solution. An important and com
PREPARATION OF THE CHELATING AGENTS
pletely feasible separation is iron from uranium. Al
though the solid polyamidoxime chelate uranium very
The polyamidoximes of the present invention may be
well, the uranium complex is not formed below a pH 45 prepared in a direct and economical manner. Their
preparation is based upon the reaction of a nitrile con
about two. Similarly iron is readily and essentially quan
taining polymer with hydroxylamine at temperatures of
titatively separated from copper if the pH of the feed
between 0 and 100° C. for from about 1A to 40 hours, in
solution is maintained between about 1.5 and about 3.5
a solvent for hydroxylamine. Solvents such as water and
since copper does not chelate appreciably below about
alcohols, e.-g., methanol, ethanol or propanol, rare satisfac
pH 3.5.
tory. As is well known in the art, hydroxylamine is
For purposes of regulating pH, both during selective
commercially available only in the form of its salts such
extraction and subsequent elution, I may use any organic
or inorganic acid with or without a buffer in order to
achieve the desired pH. The acids may be added per se, or
as an aqueous solution thereof. Convenient acids are hy—
drochloric acid, sulfuric acid, formic, oxalic, etc. It is,
of course, understood that other acids may be used and
their selection is obvious to one skilled in the art. If
an extraction is carried out in which one ion is removed
at a very low pH and subsequently a virgin polyamidox
ime is introduced at a higher pH to remove another ion,
then any convenient base, organic or inorganic, may
be introduced to raise the pH, e.g., sodium hydroxide
and potassium hydroxide and other common alkalis, the
as hydroxylamine sulfate and hydroxylamine hydrochlo
ride. Hence, it is necessary to neutralize a solution of
the salt to a pH of about 7.5 in order to utilize the free
base. It is only the free base which reacts with the nitrile
substituents.
There are a great many types of nitrile containing resins
or polymers which can be used in the present invention
to serve as starting materials for the preparation of the
polyamidoximes.
For example, the largest and most
economically feasible group comprises the homopolymer
and copolymers of acrylonitrile. In the copolymers, the
comonomer may be one or more of the common co<
selection of which is obvious to one skilled in the art. 65 polymerizable monomers such as styrene, butadiene, vinyl
The manipulation of the pH of the solution in order
to carry out the selective extraction is, of course, within
the skill of the art. In fact, in many instances due to
the inherent pH of the solution, it may not be necessary
to manually adjust the pH of the solution before bringing
it into contact with a solid polyamidoxime if the pH is
at or above the value set forth for the metal in Table I.
Thus, I have discovered that the solid polyamidoximes
chloride, vinyl acetate etc., including all the monomers
which will copolymerize with acrylonitrile. A representa
tive list appears on page 50 of the book, “The Chemistry
of Acrylonitrile,” by the American Cynamid Company
(1951). The nitrile content essential for the formation
of the solid polyamidoximes of this process can ‘arise from
other sources beside acrylonitrile. Vinyl polymers con
taining alpha-methacrylonitrile, alpha-ethacrylonitrile,
fumaryl dinitrile or vinylidene cyanide or the like are
offer an outstanding means to accomplish these separa 75 perfectly satisfactory.
It is only necessary that the poly
3,088,799
9
mer be water insoluble. It is preferred that the polymer
contain at least about 10% by weight of nitrile for opti
mum elfectiveness. Note that 10% by weight of nitrile
(CN) is about 20% by weight of nitrile calculated as
acrylonitrile. This means that in the copolymers of
acrylonitrile, the non-nitrile comonomers, one or several,
can total as much as 80% by weight of the ?nal resin
10
resin. However, in experiments with cyanoethylated cot
ton showing a nitrogen content of only 5% (10% by
weight of CN, or 20% by weight as acrylonitrile), in
some instances the conversion was as low as 40% and
the cotton amidoxirne was a perfectly operable ?brous
chelator with adequate capacity for metals. This corre
sponds to an amidoxime content of about 8.5% by weight
of the polymer. This appears to be quite low but it is
fairly certain from steric and spatial considerations which
tory, the comonom'er content obviously can be zero. Thus,
the composition of the resinous nitrile substrate can be 10 have been previously alluded to that there is little pos
sibility ‘for the chelating agent to completely satisfy the
from about 20% to 100% by Weight of acrylonitrile or
coordination number of the metal. Instead of associat
an equivalent ‘weight of another nitrile containing mono
ing with three amidoxime entities the metal can only ap
mer, e.g., alpha~methacrylonitrile and 80% to 0% of one
weight. Since the homopolymer is completely satisfac
or more comonomers.
By “copolymer” I mean polymers
proach one, or at most and only to a slight extent, two.
obtained from the polymerization of acrylonitrile or other 15 This actually is a more economical utilization of the
chelating function and makes these low concentration
nitrile containing monomers with at least one other mono
amidoximes perfectly operable and useful. The follow
mer copolymerizable therewith. Depending upon the
ing table shows how the metal capacity increases with
process of polymerization, the copolymer may be charac
amidoxime content assuming a one to one interaction.
terized as a random, alternating, graft or block copolymer.
The term polymer as used herein includes both homopoly 20 It is obvious that even polyamidoximes of very low ami
doxime content chelate appreciable quantities of heavy
mers and copolymers.
metals. There is, of course, no lower limit. As long as
In general, the molecular weight of the polymers from
the resin contains some amidoxime, it has some chelating
which the polyam-idoxime is prepared is in no way critical.
capacity.
They merely have to be high enough in molecular weight
to be substantially insoluble in water and there is no upper 25 CALCULATED METAL CAPACITY OF A POLYAMIDOXIME
limit. The commercially available acrylonitrile homo
polymers and copolymers are all completely satisfactory.
For the ?brous products the molecular weight should lie
between about 40,000 and 150,000. To carry out my
process, I prefer to use preformed ?bers in the form of 30
AS A FUNCTION OF THE AMIDOXIME CONTENT ASSUM
ING A ONE TO ONE COMPLEX
M01. weight Capacity, as percent of
4
_
Percent by weight of amidcxime
commercially available synthetic textile materials contain
of polymer
per ami
doxirne
substituent
resin weight
Gold
Uranium
ing these ?bers in their woven or non-woven form.
An additional type of nitrile containing polymer is the
natural or synthetic polymer to which acrylonitrile has
been added as a side chain on the polymer.
5, 900
2, 950
1, 180
590
393
295
236
Cyanoeth
ylated cellulose as cyanoethylated cotton or cyanoethyl
ated viscose rayon or cyanoethylated insolubilized poly
vinyl alcohol are all perfectly satisfactory for the prepara
196
169
147
131
118
tion of the solid polyamidoximes provided that the cyano
ethylation is carried out to the extent of at least about
20% ‘by weight of the polymer calculated as acrylonitrile
(10% by weight of nitrile calculated as “CN”). As is
obvious to one skilled in the art, the substrate for the
cyanoethylation need not be pure cellulose or pure poly
vinyl alcohol. The cellulose can be partially esteri?ed
or the like, the polyvinyl alcohol may contain some poly
vinyl acetate or other extraneous unit in its structure.
In
3. 4
6. 7
16. 7
4. 0
8. 0
20. 2
33. 5
50. 0
67.0
83.5
100. 0
117. 0
134. 0
150.0
167. 0
40. 4
60. 7
80. O
100. 0
121. 0
141. 0
162. 0
182.0
202. 0
I, then, have prepared resinous polyamidoximes con
taining from 8.5% to 57% by weight of amidoxime sub
stituents.
However, in the case of cyanoethylated cellu
lose, the practical limit is about 6% nitrogen introduced.
Hence, if this nitrogen which is about 12% nitrile groups
is completely converted to amidoxime, a maximum of
fact, the polyvinyl alcohol must be insolubilized before
about 25% by weight of amidoxime substituents can be
cyanoethylation to be useful in this process. This is easily
introduced into the cellulose polymer. The preceding
50
accomplished by treatment with formaldehyde or glyoxal
?gures are obviously not absolute limits of operability
or by vigorous heat treatment. It is only necessary that
since samples somewhat lower or some higher in amidox
the resin retain enough active hydroxyl sites to permit
ime content can be prepared and used. Hence, material
cyanoethylation to the degree cited. With these materials
containing as little as 5.0% or even considerably less, or
I prefer also to use preformed ?bers, that is, the com
as much as 60% by weight of amidoxime substituents de
55
mercially available natural or synthetic textile materials
pending upon the nature of the polymer would be operable
in either woven or non-woven form.
As my examples demonstrate, only a partial conversion
of the nitrile groups of nitrile containing polymers to
and within the scope of my invention. However, to as
sure a material which is not appreciably acid sensitive dur
ing its use and regeneration, an amidoxime content of
amidoxime groups will occur. It must be appreciated
about 5.0% to about 25% by weight is preferred. Of
that not all of the nitrile substituents can be converted 60 course, if a cross-linked polymer is used, then a material
to amidom'me substituents. The nitrile substituents pres
containing up to 60% by weight of amidoxime substit
ent in the inner portions of the resin are not exposed to
uents may ‘be used in contact with acids without fear of
the hydroxyla-m'ine reactant. The extent of this conver
acid sensitivity.
sion as indicated by the quantity of hydroxyamine con
There are many examples of the resinous materials de
65
sumed appears to range from about 20% to about 75%.
scribed above available in ?brous form to serve as a sub
Closed systems were used to preclude the loss of hydroxyl
strate for the preferred embodiment of this invention.
amine and thus the hydroxylamine consumed is a fair
Several sol-called acrylic ?bers are available in commercial
measure of the extent of reaction.
This means that a
100% polyacrylonitrile resin is converted to a polyami
or semi-commercial scale.
These are all, save one, based
upon acrylonitrile. The exception is based upon vinyl
doxime containing from about 19.8% to 57% by weight 70 idene cyanide and is a perfectly satisfactory alternative.
of amidoxime substituent,
—C—N]E[z
Also, there is the much publicized cyanoethylated cotton.
I have prepared cyanoethylated viscose rayon and also
N——OH
cyanoethylated polyvinyl alcohol ?ber from Japanese in
calculated as such, based upon the total weight of the 75 solu-bilized polyvinyl alcohol iiber, trade-named “Kura
3,088,799
11
12
Ion.” The ?bers listed below are all satisfactory for con
version to ?brous polyamidoximes. The percents are per
ditions of reaction, e.g., by using a lower temperature, a
shorter reaction time, a lower concentration of hydroxyl
amine, by using a granulated resin rather than a powder
(alcohol and water do not swell polyacrylonitrile appre
ciably and hence hydroxylamine will not penetrate and
cents by weight except where indicated otherwise.
Fiber
Treatment, I
Composition
11' any
react with as much polymer as in the case of the powder)
or by using a copolymer containing some non-nitrile and
therefore non-convertible monomer. A cross-linked co
>90% acrylonitrile.
Do
95-96% acrylonitrile.
>00% acrylonitrile.
About 50% acrylonitrile.
40% acrylonitrile, 60% vinyl chloride.
polymer would obviously be satisfactory. The acrylic
10 ?bers, even when almost 100% homopolymers of acry
lonitrile are so highly oriented and impervious to solvents
that conversion to the extent of acid solubiltiy is easily
avoided.
Example II
50 mole percent vinylidene cyanide, 50
mole percent vinyl acetate.
C0tton.___ Cyanoethylatei 21.7% acrylonitrile.
26.2% acrylonitrile.
20.4% acrylonitrile.
Viscose _______ __do _ _ . _
_
_ _ __
15
The detailed compositions of a few ‘additional and typ
ical ‘acrylonitrile polymers which are satisfactory for the
production of my polyamidoximes are listed as follows.
The percents are percents by weight of each monomer in
Acrylonitrile styrene copolymer (resin B of preceding
table).—A commercially ‘available acrylonitrile-styrene
copolymer containing 33% acrylonitrile and 67% styrene
by weight was converted to the .polyamidoxime as follows:
the polymer.
The resin was obtained as cubes about one quarter inch
in each dimension. These cubes were crushed in a mor
90% acrylonitrile~10% vinylacetonitrile
50% acrylonitrile-50% methacrylonitrile
tar to about ten mesh size.
97% acrylonitrile-3% vinyl acetate
50% acrylonitrile-5 0% vinyl acetate
95% acrylonitrile-5 % methyl methacrylate
amine and held at 90° C. for 24 hours While being gently
25 agitated. The solution contained 0.06 gram of hydroxyl
amine per cc. and was prepared by neutralizing an aque
65% acrylonitrile-35% methyl acrylate
45% acrylonitrile-10% methyl acrylate-45% vinyl
ous solution of hydroxylamine sulfate with an equivalent
amount of sodium hydroxide. The sodium sulfate formed
remained in the solution. After the 24 hour treatment
the granules were removed from the solution, washed with
cold water and dried. The hydroxylamine consumed in
acetate
44% acrylonitrile-44% vinyl chloride-12% methyl
.acrylate
93% acrylonitrile-7% 2-vinyl pyridine
dicated ‘a conversion of about 20% of the nitrile groups
and a ?nal amidoxime content of 7.1% by weight of the
resin. It successfully extracted the color from dilute so
26% acrylonitrile-74% butadiene
40% acrylonitrile—60% butadiene (A)
33% acrylonitrile—67% styrene (B)
100% acrylonitrile (C)
A detailed description of the procedures using the last
25 g. of this granulated resin
were added to 500 cc. of an aqueous solution of hydroxyl
35 lutions of copper sulfate, uranium acetate and gold
chloride.
I have used methanolic solutions of hydroxylamine for
most of my work because methanol is a good solvent for
hydroxylamine and its salts and because the boiling point
three polymers is given below. The process for prepar
ing the polyarnidoxime is very straightforward and it is
of methanol which is 65° C. is a convenient automatic
not necesary to vary it greatly from sample to sample. 40 temperature
control. I have also used ethanol and iso
Other useful polyamidoximes are described in Belgian
propanol with equivalent results. Other alcohols may be
Patent No. 541,496.
used but the solubility of hydroxylamine salts rapidly
In examples I to XIV a closed system was used, lie, the
diminishes as the alcohol increases in molecular weight.
re?ux condenser was capped to prevent ‘loss of the volatile
The reaction seems to be very slightly slower in water
but the ?nal product is as good as that formed using al
cohol.
hydroxylamine.
Example I
Amidoxime of polyacryloniz‘rile (C in table above) .—
40 grams of powdered polyacrylonitrile were added to
750 cc. of a methanolic solution of hydroxyl'amine. The r
solution contained 0.048 g. NHgO‘I-I per cubic centimeter.
The mixture was allowed to re?ux for 10 hours, then
cooled and the solvent removed by ?ltration. On a basis
of the amount of hydroxylamine which was reacted, about
40% of the acrylonitrile substituents were converted to '
Example III
Acrylonitrile butadiene copolymer (resin A 0)‘ preced
ing table).—A commercially available acrylonitrile-buta
diene copolymer containing 40% acrylonitrile and 60%
amidoxime. This is equal to 35.7% amidoxime based
on the ?nal resin weight. This powder, shaken with a
butadiene in crumb form was converted to the amidoxime
as follows: 25 g. of the soft granular material were heated
in 500 cc. of an aqueous solution of hydroxylamine con
taining 0.04 g. of hydroxylamine per cc. The mixture
was held at 55° C. for 24 hours. At the end of this time
the resin was removed from the liquid, washed with wa
dilute solution of copper sulfate immediately discharged
ter and dried.
the blue color and itself turned a deep green. The resid
ual copper in the solution was determined by analysis to
a conversion of 25% of the nitrile groups and a ?nal
The hydroxylamine consumed indicated
chelated uranium and gold. Analysis (gain in weight
amidoxirne content of 10.9% by weight. The resin suc
cessfully extracted the color from dilute aqueous solu
tion of copper sulfate, uranium acetate and gold chlo
and ash content) showed that it combined with more than
ride.
be 0.2 ppm. of solution.
The powder also strongly
60% of its weight of uranium.
The amidoxime is a strongly basic group and this sam
ple of uncross-linked polyacrylonitrile in its ?nely pow
dered form was easily and relatively completely converted
to a polyamidoxime which was soluble in strong mineral
The amidoximes of the intrile containing resins in
65 ?brous form were prepared in a very similar manner ex
cept that care had to be exercised to prevent damage to
the ?bers. Very gentle conditions were necessary with
some of the thermoplastic synthetic ?bers.
acid. Upon reprecipitation with alkali it seemed to be
unchanged in chelating power. This demonstrated that
Example IV
these polyamidoximes are relatively stable chemical en
tities and can go through this solution and regeneration
The amidoxime of cyanoethylated cotton-142 g. of
cyanoethylated cotton ?annel (5.7% N) were immersed
without chemical breakdown.
Solubility of the polymer in acid would frequently be
undesirable but it is easily avoided by moderating the con
in 1480 cc. of a methanolic solution of hydroxylamine.
The solvent was re?uxed for 23 hours. The cloth was
then removed, washed with water and dried. The cotton
3,088,799
14
13
diameter of a cotton ?ber. This means that ?bers ten
'Was not damaged and essentially unchanged in hand. The
times as coarse as cotton (.20 mm.) are equivalent to
hydroxylamine consumed indicated an amidoxime con
the surface area of commercial resins. Thus, cotton is
tent of 9.3% of the ?nal weight of the modi?ed cotton.
ten times better_as to surface-volume ratio than the com
Samples of it removed most of the gold, uranium and
copper from dilute solutions of these metals by a simple 5 mercial ion exchange resins. Therefore, by passing a
?ltration step. The solutions were merely slowly ?ltered
liquid through one or more layers of a textile fabric
through the treated cloth.
amidoxime, I achieve surface contact equivalent to what
Example V
would be realized by the very, very slow percolation of
The amidoxime of an acrylic ?ber.(Zefmn) .-—8.6 grams
'of Zefran fabric (a light weight twill) were immersed 10
thg?hquld {111110515}! 3‘ bedl Of eF’gIeh‘hY ?ge resm' t1 .
eme’
e
mus p0 yaml Oxlmes 0 er 3' grea .y 1m'
in 376 cc. of a 0.045 g. NHgOI-I/cc. solution in methanol.
pmyed .Speed or throughput over any 9ther fPIm‘. Fibrous
The mixture was re?uxed for ten hours. The cloth was
then removed Washed with Water and dried The hy_
amldoxlmes’ because of the sheed wlth whlch hquld can
pass through them with effective contact and because of
droxylamine ‘consumed indicated an amidoxime content
the efhclehcy with which the 'alhido‘xlme gmhps Selectively
of 9_7% by Weight’ As with the Cotton derivative’ this 15 extract metals, make it possible to selectively recover
cloth strongly chelated a number of heavy metals.
The following examples, set ‘forth in tabular ‘form,
mineral values from very large Volumes‘ of eXtremelY
dilute solutions. The fabric polyamidoximes have the
were carried out in the same manner as indicated in the
furth?l‘ advantage that they are self-supporting structures.
preceding examples. As previously indicated, all prepara-
They may take the form of a ?lter cloth, in any geo
tions were carried out in a closed system.
20 metrical form, e.g., rectangular or circular; they may be
Mole
ratiou
Ex.
Original ?ber
VI.-- Acrilan ________________ __
VIL. Cotton (print) cyanoethylated.
Amidox
Gms.
NHZOH/ fabric
fabric
4.35:1
2.8:1
Gms.
NHgOH
5.3
64.0
14.3
23.9
NHzOHb Time, "I‘emp.,
oonc.,
hours
° 0.
g./cc.
.032
.035
1
18
Gms.
Hand
65 Very sl.sti?__-__
65 .____d0 _________ __
_
ime,per
NHZOH cent by
reacted weight of
the ?ber
.19
3.35
8.0
8.5
.11
12.3
.19
13.7
2.10:1
1.6
2.2
.023
0.5
65
s1. sti?enlngun
2.01
2.5
4.5
.055
2
25
_____do ......... .-
2.011
8.0
10.0
.023
1.5
50
No change.
.38
8.6
2.41
3.6
5.4
.023
4
c5
s1. yellow _____ __
.20
10.0
2.011
‘1.0:1
6.3
6.8
7.88
16.9
.023
.045
1.5
1
50
50
s1. stiffening"
Very sl. stiff
.39
.34
11.0
8.9
4.31
6.0
16.1
.042
s
62
No change ____ ._
.29 .
8.5
n A molecular weight of 246 was used for the cyanoethylated cotton cloth (based on N content of 5.7%). The acrylic ?bers
were assumed to be polymers of acrylonitrile and a molecular Weight of 53 was used.
b This involves an excess of NH'ZOH over the polymer and particularly where part of the polymer is derived from a non-con
vertible comonomer.
mounted upon a frame or be formed into a sleeve or sack
Although I have concentrated my studies on fabrics, I
have also studied ?bers. I have found that the ?bers 40 of any size or shape.
The temperatures employed during my selective extrac
behave exactly as the fabrics made from the ?bers. The
tion and elution processes are not critical. Since the solid
conversion of the 'nitrile ‘group to amidoxime can be
effected in a manner similar to the preceding examples on
?bers and yarns as well as on the non-woven fabrics ob
tained from these ?bers and yarns.
Also, I have found that these polyamidoximes in granu
lar or powder form are effective and useful for the ex
traction of ‘heavy metals. However, as previously set
forth, the polyamidoximes in ?brous form are a par
polyamidoxime whether in the form of granules, ?bers,
fabrics, etc., is stable up to about 125° C., I may use tem
peratures up to such values. Of course, lower tempera
tures, even down to the freezing point of the solutions
may be used. In other Words, the temperature of the ma
terials, which is usually room temperature, was found to
be convenient. Of course, in industrial processes, the
temperature of the liquid bodies to be treated may be
50 above or below room temperature; but as stated above,
tile ?bers, are equivalent to very ?ne powders in two
these temperatures are not critical.
of their three dimensions and the surface area per unit
In addition to aqueous media including water as well as
volume offered by such ?bers is almost equal to that
such commodities as beer, wines, milk, etc., my process
of powders of the same diameter. A high surface area
per unit volume is, of course, a very desirable feature of 55 may be carried out in non-aqueous media, e.g., methanol,
ethanol, acetone or any solvent which will dissolve traces
any solid intended for the treatment of liquids. A simple
of metal salts.
calculation shows how ?bers and spherical resin granules
ticularly preferred embodiment. Fibers, i.e., normal tex
compare. Neglecting the ends, which shortcut penalizes
the ?bers very slightly, the ratio of surface area to vol
ume is 4 over d 1for ?bers and‘6 over d for spheres. V In
other words, a ?ber is equivalent to a sphere of 50%
greater diameter and the following relationship exists be
tween ?bers and equivalent spherical resin granules.
Fiber
1
Sphere
diameter,
mm.
Diameter, Mesh-size
SELECTIVE EXTRACTION
The following seven examples illustrate the selective
removal and subsequent recovery of iron from aqueous
solutions containing said iron in admixture with (a)
other chelatable heavy metal ions and (b) non-chelatable
metal ions. In each example, a solution was prepared by
dissolving a su?icient amount of salt of the desired metal
65 to supply the indicated number of grams of metal per 100
cc. of ?nal volume which includes the volume of the acid
solution needed to adjust the pH. The pH of the solution
was adjusted to the given value by addition of hydro
mm.
. 02
. 04
. 09
. 03
. 06
. 12
—325
—230
—-120
. 20
. 30
-— 50
chloric acid. Then, a 4 gram woven polyamidoxime
70 fabric prepared in accordance with Example V was im
mersed into each of the 100 cc. solutions containing the
mixtures of metal ‘ions. The large quantities of poly
amidoxime chelator fabric were used to ‘assure excess
A 50 mesh resin (0.30 mm. diameter) is the ?nest
chelating capacity and to enhance the extraction of the
which is practicable and .02 mm. is the average mean 75 second metal if it had a tendency to complex. After the
3,088,799
15
10
fabric and solution were in contact for 8 hours at room
REMOVED CA'l‘IONS (BY CHELATION)
temperature, the fabric was removed and carefully washed
free of any original solution which may have been me
_
chanically held to the fabric.
_
_
The metal ions
which
are
I
Cation
Grns.
cation
chelated to the fabric were eluted therefrom by immersing 5
the fabric in a 100 cc. solution containing 5% by we1ght
Iron
of hydrochloric acid (pH <1). The metal content Whlch
was freed from the fabric in this manner was determined
Aluminum
.
___.
91
Q
_
0.0
0
Calcium ___________________________________ __
0.0
0
sodium _____________________________________ __
Example XV
of
0 on
010
M15535}?"""""""""" "I: """"""" ‘I:
by standard analytical procedures.
Percent by
0
Q0
10
INITIAL SOLUTION (pH=1.02)
Salt
Example XIX
Cation
Gms_
INITIAL SOLUTION (pI-I=3. 02)
cation
Ferric chloride_ -
Iron
0. 110
Uranyl acetate..
___- Ur'minm
0,010
15
Salt
Cation
Ferric chloride ____________________ __
REMOVED CATIONS (BY CHELATION)
Gms.
Ir
Chrome 111mm ------------------- -
2O
Gms.
cation
Cation
Percent by
Weight of
REMOVED CATIONS (BY CIIELATION)
canon
Iron
0. 100
91
Uranium ____________________________________ _.
0.00
O
Cation
Grns.
Percent by
cation
weight of
canon
25
Example XVI
Iron _________________________________________ __
0. 0147
05
Chromium __________________________________ __
0.010
10
INITIAL SOLUTION (pH=2.0)
30
Salt
Cation
Example XX
INITIAL SOLUTION (pH=3. 5)
c?‘gfr-l
Ferric chl0ride_
Iron
0. 050
Uranylacetatc ____________________ ._
Uranium ............ _-
0.500
salt
REMOVED @ATIONS <BY CHELATION)
Gms.
_
,
iilltfni‘éii’iég‘ta::::::::::::::::::: isrgiih'?ijjijjjiiljljjj
Percent by
cation
331;;
‘
35
Cation
can”
3:‘1’83
4
Weight of
REMOVED CA’I‘IONS (BY OHELATION)
cation
Iron
Uranium
___
0. 050
I
100
0. 001
40
Salt
Calcium chloride _______ __
Sodium chloride _ _ _ _ . _ _ _
canon
0. 063
100
°~ 0
°
Example XXI
Gms.
cation
INITIAL SOLUTION (pH=2. 0)
Iron
0.0112 50
Nickel .............. __
0.100
Aluminum
0.500
_
weig tot
45
Cation
Ferric chloride___
Percegt
by
-
cation
Baum ------------------------------------- --
INITIAL SOLUTION (pH=2.5)
Nickel(ous) chloride __________ __
Gms.
a ion
Iron
Example XVII
Aluminum nitrate
C t
2
_
Calcium ____________ __
0.500
_ _ . . _ ..
Sodium ............. __
0.500
REMOVED CATIONS (BY CHELATION)
Salt
Cation
Grns.
cation
Ferric chloride ____________________ __
Iron _________________ __
00055
Urauyl acetate ____________________ __
Uranium ____________ _.
0. 054
55
REMOVED CATIONS (BY CIIELATION)
Gms.
cation
Cation
Percent by
weight of
cation
Cation
Iron _____________________________ ._
0.011
98
N lekel __________________________ -.
Aluminum
Calcium
0- 0
0
0.0
0.
O
00
Sodium _____________________________________ __
0.0
0
Gms.
Percent by
cation
weight of
cation
00
Iron _________________________________________ lUranium ____________________________________ __
0. 054
Q0
98
0
The following seven examples were also carried out in
Example XVIII
IN
I
IT A
L S
I
seven examples.
= .
OLU'I‘ ON (pH 3 0)
Salt
Cation
Ferric chloride__ ._
Gms.
0.0122
M'mmnesc
___
Calcium chloride __________________ __
Sodium chloride ___________________ _.
Aluminum
Example XXII
INITIAL SOLUTION (pH=2,9)
cation
Iron
Manganous acetate
Aluminum nitrate
65 accordance with the procedure employed in the preceding
70
Salt
Cation
Cupric sulfate _____________________ __
Uranyl acetate ____________________ __
Copper ______________ __
Uranium ____________ __
0. 100
__
0_ 500
Calcium ________ ._
Sodium _____________ _.
0.500
0.500
75
Gms.
cation
0100
0.110
3,088,799
18
Example XX VII
REMOVED CATIONS (BY CHELATION)
INITIAL SOLUTION (pH=3.26)
Cation
Gms.
Percent by
cation,
weight of
'
Salt
Uranium
0. 110
100
Copper ______________________________________ _-
0. 009
9
Example XXIII
Gms.
cation
Salt
Cation
‘
NickeKous) Phlnririo
Uranyl acetate.
Uranium
O. 10!)
Zinc acetate
7inn
0.100
REMOVED CATIONS (BY CHELATION)
10
lNl’I‘LAL SOLUTION (pH=3.5)
Cupric acetate- . .
Cation
cation
Gms.
cation
Cation
Gms.
cation
Copper
0. 180
Nickel- _
0. 099
15 Uranium
Zinn
\
Percent by
weight of
cation
0,0. 100
0
1000
Example XX VIII
REMOVED CA'I‘IONS (BY CHELATION)
INITIAL SOLUTION (pH=-3.l6)
Gms.
Cation
cation
Percent by 20
weight of
Salt
cation
Cation
Copper __________ __
0. 162
90
Nickel __________ _.
0. 005
5
Uranyl acetate-
Uranium
0.100
Stannous chloride.
Tin-
0.100
Example XXIV
REMOVED CATIONS (BY CIIELATION)
INITIAL SOLUTION (pH=1.9)
Cation
Salt
Cation
Chlorauric acid. . . _
Lead acetate. .
'
Gms.
cation
Gold
0. 100
Lead
0. 100
Gms.
cation
Cation
Gnlri
0. 100
Tom]
0. 0
35
Percent by
weight of
cation
Percent by
weight of
cation
Uranium
U. 099
Tin _________________________________________ -.
0.0
99
0
Example XXIX
Recovery of copper from a cuprammonium c0m1plex.—
0.391 g. of cupric sulfate, CuSO4-5H2O, and ‘0.445 g.
of manganese acetate, Mn(C2H3O2)2-4H2O, were dis
solved in 100 cc. of distilled water and an approximately
40 one cc. of a concentrated solution of ammonium hydrox
100
0
ide was added to develop the strong cuprammonium blue
color. This indicated the presence of the cuprammonium
Example XXV
cation, Cu(NH3)4+2. The above solution thus contained:
INITIAL SOLUTION (pH=4.05)
G.
Cation
Uranyl acetate. .
Lead acetate- . ._
Gms.
cation
30
REMOVED CATIONS (BY CHELATION)
Salt
Gms.
cation
Uranium
Lead__
45
Gms.
cation
’
Gms.
cation
0.100
0.100
and had a pH of 8.3. A small sample of a ?brous poly
amidoxime was immersed in the solution and allowed to
50 stand at room temperature for two hours. During this
time, the solution became colorless and the fabric turned
greenish black. However, this color was observed not to
0. 100
0. 100
REMOVED CATIONS (BY CHELATION)
Cation
Copper
Manganese
be the same as the bright green color of a copper chelate
Percent by
weight of
cation
complex formed in the absence of ammonia. Hence, it
55 may be concluded that chelation occurred between the
amidoxime groups and the cuprammonium anion. How
Uranin m
"Lead
0. 099
0. 00
99
0
covered. The fabric was removed, washed, dried and
ashéd. The ash showed no manganese. The original so
60 lution after fabric was removed showed 9 parts per mil
lion of copper. This indicated an essentially quantitative
Example XXVI
INITIAL SOLUTION (pH=3.46)
Salt
Cation
recovery of copper in the presence of ammonia. A sec
ond chelated sample prepared in the same manner was
Gms.
cation
eluted with 5% by weight aqueous solution of sulfuric
Uranyl acetate- .
Uranium "
0. 100
Thorium chloride _________________ -_
Thorium__-.________ _.
0. 100
Gms.
cation
65 acid. The eluate showed the usual light blue color of the
hydrated cupric ion.
The ?brous polyamidoxime of the above Example
XXIX was prepared according to the directions of Ex
REMOVED CATIONS (BY CHELATION)
Cation
ever, on elution with acid, the free copper ion was re
ample V, but on a much larger scale. Twenty-?ve yards
Percent by 70 of a Zefran shirting fabric were treated for 4 hours at
weight of
60° C. in a commercial dye beck containing 6650 grams
cation
of hydroxylamine hydrochloride in 55 gallons of water.
5800 grams of potassium hydroxide were also present to
Uranium ____________________________________ --
Thorium
\
0. 099
U. 005
99
5
free the hydroxylamine from its hydrochloride salt. The
cloth was then removed, washed with water and dried.
3,088,799
19
20
The fabric showed 2.4% by weight of oxime nitrogen con
In the above examples, in no instance was more than a
tent, i.e., almost exactly equivalent to the 9.7% by weight
hardly measurable trace of lead, barium or aluminum
amidoxime content of the material of Example V.
The following examples demonstrate the excellent ca
found. Most of the tests for these metals were entirely
negative.
pacity of the chelating materials. In each example the 5
?brous chelator of Example XXIX was immersed in a
solution containing a 100% excess of the metal ion to be
extracted. The excess was determined by assuming a 1
The fll11_1I1 pickup is not achieved ‘in every instance,
but is reahzed freqlgently elgough to establlsh It as the
true Potential eapaelty- It 15 qulte reasonable that not
every metal 18 Chelated t0 the'same flegfee even among
to 1 Combination of the amidoxime functional group and
those which are chelated. It is possible that the metals
the metal ion. The fabric, as stated previously, showed 10 above Whleh _5h0W Plekup appfeelably 1e5s_tha_n the eel
by analysis 2.4% by Weight of oxime nitrogen or 0,161
culated capacities have less favorable distribution coe?i
atom percent 0f oxime nitrogen
If each amidoxjme
cients and a considerably higher concentration
group joined one metal atom, the number of atoms of
the solu
_
‘lions wohld be necessary to fully load the fahl'le-
oxime nitrogen equal the number of atoms of metal. The
‘ The PIekPP Values Clearly delhenetfate the exeeedlngly
metal content at saturation should therefore be 0.161 mul- 15 high eapaelfy of these polyamldoxlme chelatlng agents
tiplied by the atomic weight of the metal. Also in each
when used 111 eerrylllg Qut my Process of seleetlve eXh'ae‘
example the extraneous nonchelatable metal cations, lead,
aluminum, and barium were each present in amounts of
0.100 gram to demonstrate selectivity and non-interfer-
“011- The _fab1'_1° ‘used_ 111 the test 13 no} the mos? hlghly
Converted, 143-, It contalrled 9.8% by Weight of amidoxime
SubSt}tu¢IltS- Hence, with a higher conversion of nitrile
ence as well as the capacity of the fabric. The example 20 substltl-fents t0 amldoxlme substituents, notably higher
directed to the extraction of uranium is given in detail
(Example XXX). The other examples were carried out
capaeltles can be achleved
Example XLIV
in the same manner and are summarized in the table fol-
-
lowing Example XXX. In each instance, the metal to be
A 4 gram “.mple 9f cyanoethylatiad cotton. was un
chelated was present in an amount exactly twice the cal- 25 merse’d £9.1- 2 mmutes m a 5% by welghi solutlon of m‘
culated capacity of the fabric sample used and ions of
when‘? dnsocyimate (89% byWe1ght2’4'1somer.and 20%
lead, aluminum and barium were each present in amounts
by Weight .2’6'1SOmer) m benzene‘ The resuitmg cross
Of 0100 granL Thc PH which is disclosed in each eX_
linked fabric was then centrifuged, vacuum desiccated and
-
heated at 110° C. for one hour.
Then the fabric was
ample represents the value which resulted from upward 3O Washed with benzene dried soaked in Water for foul.
-
e
I
)
adjustrilent to promote chelatlqn’ downward adjustment
hours and ?nally dried. The total weight gain was found
to clarify the heavy metal solution, or the natural pH of
the salt mlxmre‘
Example XXX
.
.
.
A. 400 cc' §olutlon_was Prepared by cilssolvmg the fol‘
lowing‘salts in su?‘icient amounts to yield the_indicated
qual?ltles 01‘- the heavy metal 10118. After solution of the
7
to be 0 221 gram
The above cross-linked fabric was heated for 6 hours
at 75° C. in an aqueous hydroxylamine solution contain
35 ing 0.045 gram hydroxylamine per cc. of water.
There
after the fabric which was a cross-linked polyamidoxime
was water Washed and dried_
A sample of the above fabric quantitatively removed
Salts The PH Was adlhsted t0 5-5 ‘by addition of a few
the uranium present in an aqueous solution which con
drops of a 10% by weight aqueous solution of sodium hy- 40 tained ‘0.1% by weight of uranium present as uranyl
droxide. The total volume after adjusting the pH was
acetate, 2% by weight of sodium present as sodium
400 cc.
chloride and 2% by weight of calcium present as cal
cium chloride. The pH of the solution before treatment
I
on
W . ht f
1
ionelggms?)
Sn t
with the fabric was 4. _ The fabric was_subseqnently
45 treated with a 1% by weight aqueous solution of hydro
chloric acid in order to elute the uranium. No damage
Uranium ...................... _.
0. 400
3331-51-15:;
8: $8 ??’lgjégjggzg?
__:
Barium ....................... -_
0.100
UO;(C1H3O2),-2H,O,
BaClg.2HzO.
of the fabric was observed.
By comparison, a polyamidoxime prepared from cyano
'
ethylated cotton, but not treated with m-toluene diisocy
To the above solution, 0.5164 gram of the ?brous polyaniidoxime was immersed-in the solution. After immer-
50 anate in order to introduce cross-linking, rapidly disin
tegrated and partially dissolved when contacted with the
1% hydrochloric acid solution.
Example XLV
sion in the solution overnight at room temperature, dur-
,
ing which time the fabric turned a strong bright orange 55
color, the fabric was removed, washed thoroughly with
distilled water, dried and ashed. 'Ihe ash was analyzed
for the four metals. The analysis indicated 39% by
weight of uranium based upon the original fabric weight, 60
a trace of barium, no aluminum and no lead.
Ex.
Salt
Metal
Atomic
weight
pH of
sol.
. .
A solutlon contammg
0.035%
0.035%
0.035%
0.035 %
0.035 %
by weight Fe present as ferric chloride
by weight Au present as chlorauric acid
by weight Cu present as copper chloride
by weight Ba present as barium chloride
by weight Al present as aluminum nitrate
Pick-up Pick-up
calculated
(percent)
actual
Percent
(percent) of theory
Vanadium sulfate _____ __
51
3.9
8.4
8.4
Ca. 100
Ohromic nitrate__
Ferric chloride___
52
56
3. 9
3.0
8. 5
9. 2
3.6
9.1
43
Ca. 100
_ Oobaltous nitrate__
59
5.5
9.7
3.7
38
Nickel(ous) chloride
Cupric suliate____
Ruthenium chl0ride_____
59
64
101
5. 9
6.5
2. 2
9. 7
10.5
16. 6
3.0
10.3
4. 4
31
(111.100
27
Rhodium chloride _____ __ Rh
103
Palladium chloride-
107
3.2
17.5
17.1
Ca.100
195
197
204
2. 5
2.0
4. 6
32.0
32.4
34. 2
31.0
32.0
0. 5
Ca. 100
Ca.100
10
238
5.5
39.2
39.0
100
_
Platinie chloride_
Chlorauric acid__
Thalliuni nitrate.
Uranium acetate___
_ Uranium.
3.4
16.9
16.3
022.100
3,088,799
21
was prepared.
22
stance, about 25% to 35% by weight of such metals
based on the total weight of the complex, it will serve
as a relatively light weight and ?exible radiation shield.
The pH as prepared was found to be
3.5. It was adjusted downward to about 2.5 by the ad
dition of a few drops of hydrochloric acid. A 2 gram
Also, the solid polyamidoxime may serve as a catalyst
carrier for reactions which are promoted by traces of
sample of the polyamidoxime fabric of Example XXIX
was allowed to stand in the solution overnight. The
solution turned bluish and the fabric brown. The fabric
which had chelated both the gold and iron ions was
washed with water and then soaked in a 5% HCl solu~
tion vfor a few minutes. The fabric was washed again
mixtures of various heavy metals in amounts of, e.g.,
about 1% to 5% by weight of the metals based on the
total weight of the complex. By use of polyamidoximes,
catalyst carriers containing mixtures of metals in prede
and ignited. The ash accounted for all of the gold orig 10 termined quantity and ratio may be prepared. In such
system, the catalyst mixture is readily removed when
inally in the system. The ash also showed a trace of
no longer wanted. Of course, by the practice of my
iron and no trace of copper or barium. The acid solu
process of selective extraction, I may extract a single
tion was analyzed for iron. It contained 93% of the
ion. In such cases, the polyamidoxime when extracted
iron originally added and 5% 0f the copper. The original
solution which has been extracted {once was adjusted to 15 with a single ion may also be used as a radiation shield,
e.g., when chelated with palladium, or as a catalyst car
a pH of 6 by the addition of a 10% NaOH solution. A
rier for reactions which are promoted by traces of a
second piece of same polyamidoxime fabric was allowed
single metal such as copper and nickel. Also, whether
to soak in this solution for two hours. It was then re
chelated with a single radioactive metal isotope, e.g.
moved, washed and eluted with a 5% HCl solution.
The eluate, upon analysis, showed a faint qualitative test 20 U235, or a plurality of radioactive metals, it will serve
as an e?icient neutron source which may be used as a
for iron and none for gold. It contained 87% of the
fuel element in a reactor. For example, complexes of
active uranium isotopes and ?brous polyamidoximes car
copper initially added.
The following three examples illustrate the practice
of my invention in media other than water.
rying from about 5% to about 40% by weight of uranium,
25 based on the total weight of the complex, are extremely
Example XLVI
useful especially because of the efficient utilization of the
neutrons. The disintegrating atoms are essentially on
the surface of the material. There is no external layer
of extraneous material to slow or absorb the neutrons.
perature in a solution of methanol saturated with sodium
acetate and copper sulfate. The fabric turned light blue 30 Thus, the neutrons are essentially 100% available for
A polyamidoxime fabric prepared from Zefran as de
scribed in Example XXIX was immersed at room tem
which indicated copper pickup.
triggering chemical reactions or transmutation changes.
In the form of a fabric, the uranium complexed poly
amidoxime is much superior to an extremely thin sheet
The methanolic solu
tion after treatment with the fabric gave no test for
copper.
of uranium or uranium oxide. Such a metal or oxide
35 sheet of one of the active isotopes would be dif?cult and
Example XLVII
A polyamidoxime fabric prepared from Zefran as de
scribed in Example XXIX was immersed at room tem
dangerous to fabricate and would be very feeble. The
fabric is quite strong and all the operations needed to
perature in a solution of ethanol saturated with zinc ace
prepare the fabric take place before the dangerous radio‘
tate and uranium acetate. The fabric turned pale yellow
active isotope is added. The fabric is also easily de
indicating uranium pickup. The fabric showed no zinc. 40 formable to yield desired structures and shapes. Fur
The solution after treatment with the fabric gave no test
thermore, a mass of ?bers carrying one of the radio
active isotopes is readily permeable to gases and liquids
for uranium.
Example XLVIII
A polyamidoxime fabric prepared from Zefran as de
scribed in Example XXIX was immersed at room tem
perature in a solution of ethanol saturated with zinc
acetate and ferric chloride. The fabric turned brown.
The solution after treatment with the fabric showed only
a faint trace of iron. The fabric showed no zinc.
reaction between chemicals, etc.
It must be appreciated that many modi?cations within
the scope of the present invention will occur to those
The 50 skilled in the art. ‘For instance, a single metal or various
fabric was subsequently eluted by treatment with a small
quantity of acid. The eluate was yellow and gave a very
strong test for iron.
which are to be altered by the energy of the radioactive
change. Thus, when used as fuel elements, an activated
source of energy is supplied for purposes of sterilization,
-
Example XLIX
0.1 gram of a ?brous polyamidoxime prepared from
Zefran as described in Example XXIX was immersed
in 25 cc. of a solution containing 0.0132 gram per liter
plutonium nitrate (13.2 ppm), 18.9' grams per liter of
nitric acid and 51' ‘grams per liter of aluminum (from
aluminum nitrate). The pH was about 0.6. The fabric
chelated 40% of the plutonium in one hour and 60%
after standing overnight. Plutonium as indicated above
appears to'behave like the more common noble metals
combinations of the metals selected from Table I may
be extracted from mixtures of the metals of Table I,
alone or in admixture with the ions of the unextractable
metals. Also, a single ion from Table I in admixture with
55 one or several of the unextractable metals may be recov
ered. Similarly, a polyamidoxime which has been chelated
with a mixture of several of the metals selected from
Table I, may be selectively eluted by adjustment of the
pH so that the ions may be, if desired, separated from
the polyamidoxime. Also, my process is admirably
adapted for continuous use from the standpoint of selec
tive extraction, selective elution and regeneration of the
polyamidoxime. For instance, a mechanically driven end
less belt comprising a solid polyamidoxime fabric may be
and is not eluted from the polyainidoxime by strong acid. 65 continuously passed through a plurality of tanks which
The polyamidoxime whether in the form of granules,
may contain, in series, the solution to be treated, a wash
?bers, yarns, woven or non-woven fabrics, etc., has many
uses.
A principal use is in the selective recovery of
the metal ions in Table I from solutions containing
same. The resulting chelated polyamidoxime in most
instances may be eluted with acid to recover the metals.
ing tank, an acid tank for elution and regeneration, a
further washing tank, etc. ‘Each tank may be connected
to both ?lling and emptying means, which means may be
regulated in their operation in a timed relationship with
Moreover, in view of the exceedingly high capacities
the travel of the endless belt.
which may be achieved, the chelated polyamidoxime may
ing application, Serial No. 673,157, ?led July 22, 1957,
This application is a continuation-in-part of my copend
be used as such. 1?or instance, if the solid polyamidoxime
is chelated with a mixture of the noble metals, for in 75 now abandoned.
3,088,799
23
24
Having described my invention, what I claim as new
and desire to secure by Letters Patent is:
1. A process for selectively extracting at least one poly
valent metal selected from the group consisting of:
which comprises the steps of bringing a solid, solvent
insoluble polyamidoxime into contact with said solution
at a pH not numerically lower than the numerical value
set forth above and not greater than the pH at which
said metal precipitates out of solution, whereby said metal
reacts with the amidoxime radicals of said polyamidoxime
pH
Plutonium
Gold
___________________________ _ _
<1
_______________________________ __
<1
to form a chelate structure therewith and thereafter sepa
____________________________ __
<1
rating the resulting chelated solid polyamidoxime from
___________________________ __
<1
Platinum
Palladium
Rhodium ____________________________ __ About 1.0
Iron ________________________________ __ About 1.5
Thallium ____________________________ __ About 1.5
10
polyvalent metal selected from the group consisting of:
Plutonium
Vanadium
Vanadium ____________________________ __ About 1.5
Uranium _____________________________ __ About ‘2.0
Ruthenium ___________________________ __ About 2.0
said solution.
5. A process for selectively extracting at least one
Gold
Platinum
Uranium
Ruthenium
Rhodium
Iron
Thallium
Nickel
Cobalt
Chromium
15 Palladium
Copper ______________________________ __ About 3.5
Nickel _______________________________ __ About 4.0
Cobalt _______________________________ __ About 4.0
Chromium ___________________________ __ About 4.0
Copper
20 from a solution comprising at least one polyvalent metal
from a solution comprising
selected from the group consisting of:
(1) at least one of said metals and
pH
(2) at least one other metal selected from the group
consisting of
(a) at least one of said metals and
(b) the remaining metals of the periodic chart
25
<1
Gold
<1
_______________________________ __
Platinum
Palladium
of the elements
so that at least one metal remains in solution compris
ing the steps of bringing said solution into contact with a
solid, solvent insoluble polyamidoxime at a pH not nu 30
merically lower than the numerical value set forth above
and not greater than the pH at which said metal precipi
tates out of solution whereby said metal reacts with the
Plutonium ___________________________ __
____________________________ __
<1
__._..._-_.__.' ___________________ __
<1
Rhodium ____________________________ __
Iron ________________________________ __
Thallium ____________________________ __
Vanadium ___________________________ __
Uranium ____________________________ __
Ruthenium ___________________________ __
About 1.0
About 1.5
About 1.5
About 1.5
About 2.0
About 2.0
amidoxime radicals of said polyamidoxime to form a
Copper ______________________________ __ About 3.5
chelate structure therewith and thereafter separating the
resulting chelated solid polyamidoxime from said solu
tion.
2. The process of claim 1 in which said polyamidoxime
is a polymer containing from about 5.0% to about 60%
Nickel ______________________________ __ About 4.0
Cobalt ______________________________ __ About 4.0
Chromium ___________________________ __ About 4.0
by Weight of amidoxime substituents.
3. The process of claim 1 in which said polyarnidoxime
is a high molecular weight organic nitrile containing poly
mer selected from the group consisting of a polymer of
acrylonitrile, a polymer of vinylidine cyanide, cyano
ethylated cellulose and derivatives thereof and cyanoeth
ylated polyvinyl alcohol, said polymer having at least
some of said nitrile radicals converted to amidoxime
radicals.
4. A process for selectively extracting from at least
one polyvalent metal up to one less than the total number
of polyvalent metals selected from the group consisting of:
Plutonium
Vanadium
Gold
Uranium
Platinum
Ruthenium
Palladium
Copper
Rhodium
Iron
Nickel
Cobalt
Thallium
Chromium
from a solution comprising at least two polyvalent metals
selected from the group consisting of:
pH
Plutonium
Gold
___________________________ _ _
_______________________________ __
Platinum
____________________________ __
<1
<1
<1
plus at least one other metal of the remaining metals of
the periodic chart of the elements which comprises the
40 steps of bringing a solid, solvent insoluble polyamidoxime
into contact with said solution at a pH not numerically
lower than the numerical value set forth above and not
greater than the pH at which said metal precipitates out
of solution, whereby said metal reacts with the amidoxime
radicals of said polyamidoxime to form a chelate struc
ture therewith and thereafter separating the resulting solid
chelated polyamidoxime from said solution.
6. A process for selectively extracting a polyvalent
metal selected from the group consisting of:
pH
Plutonium ___________________________ __
<1
Gold
<1
_______________________________ __
Platinum
Palladium
____________________________ __
<1
___________________________ __
<1
Rhodium ____________________________ __
Iron ________________________________ __
Thallium ____________________________ __
Vanadium ___________________________ __
Uranium ____________________________ __
Ruthenium ___________________________ __
About 1.0
About 1.5
About 1.5
About 1.5
About 2.0
About 2.0
Copper ______________________________ __ About 3.5
Nickel ______________________________ __ About 4.0
Cobalt ______________________________ __ About 4.0
Chromium ___________________________ __ About 4.0
___________________________ __
<1
65 from a solution comprising mixtures of polyvalent metals
Rhodium ____________________________ __
Iron ________________________________ __
Thallium _____________________________ __
Vanadium ___________________________ ..
Uranium _____________________________ __
Ruthenium ___________________________ __
About 1.0
About 1.5
About 1.5
About 1.5
About 2.0
About 2.0
selected from the group consisting of:
(1) at least two of said metals, and
(2) at least one of said metals plus at least one other
metal of the remaining metals of the periodic chart
70
of the elements
which comprises the steps of bringing a solid, solvent
insoluble polyamidoxime into contact with said solution
at a pH not numerically lower than the numerical value
Palladium
Copper ______________________________ __ About 3.5
Nickel
Cobalt
______________________________ __ About 4.0
______________________________ __ About 4.0
Chromium ___________________________ __ About 4.0
set forth above and not greater than the pH at which
said metal precipitates out of solution, whereby said metal
3,088,799
25
26
to form a chelate structure therewith and thereafter sep
amidoxime comprising the steps of bringing said chelated
solid, solvent insoluble polyamidoxime into contact with
arating the resulting chelated solid polyamidoxime from
a solution at a pH not numerically greater than the nu
reacts with the amidoxime radicals of said polyamidoxime
merical value set forth above for said metals to be eluted
said solution.
so that at least from one of said metals up to one less
7. The process of claim 6 in which said polyvalent
than the total number of said metals is freed from its
metal is uranium and said pH is not numerically lower
complex with said polyamidoxime and enters said solu
than about 2.0 and not greater than the pH at which said
tion and thereafter separating the solid polyamidoxime
uranium precipitates out of solution.
from the resulting metal enriched solution.
8. The process of claim 6 in which said polyvalent
12. A solid, solvent insoluble polyamidoxime com
metal is plutonium and said pH is not numerically lower 10
plexed with at least two polyvalent metals selected from
than <1 and not greater than the pH at which said
the group consisting of:
plutonium precipitates out of solution.
9. A process for selectively extracting iron from an
Plutonium
Vanadium
aqueous solution comprising a mixture of iron and urani
Gold
Uranium
um which comprises the steps of bringing said solution 15 Platinum
Ruthenium
into contact with a solid, solvent insoluble polyamidoxime
Palladium
‘Oopper
at a pH numerically below about 2.0 and numerically
Rhodium
Nickel
above about 1.5 whereby said iron reacts with the
Iron
Cob alt
amidoxime radicals of said polyamidoxime to form a
Thallium
Chromium
chelate structure and thereafter separating the resulting 20
I13.
The
complexed
composition
of claim 12 in which
chelated solid polyamidoxime from the solution.
said polyamidoxime contains from about 5% to about
10. A process for selectively extracting iron from an
60% by weight of amidoxime substituents.
aqueous solution comprising a mixture of iron and nickel
'14. The complexed composition of claim 12 in which
which comprises the steps of bringing said solution into
contact with a solid, solvent insoluble polyamidoxime at 25 said polyamidoxime is a high molecular weight organic
nitrile containing polymer selected from the group con
a pH numerically below about 4.0 and numerically above
sisting of a polymer of acrylonitrile, a polymer of vinyli
about 1.5 whereby said iron reacts with the amidoxime
dine
cyanide, cyanoethylated cellulose and derivatives
radicals of said polyamidoxime to form a chelate struc
thereof and cyanoethylated polyvinyl alcohol, said poly
ture and thereafter separating the resulting chelated solid
30 mer having at least some of said nitrile radicals converted
polyamidoxime from the solution.
to amidoxime radicals.
.11. A process for selectively eluting at least one poly
valent metal up to one less than the total number of
References Cited in the ?le of this patent
UNITED STATES PATENTS
polyvalent metals selected from the group consisting of:
pH
Rhodium
Iron
_....__
Thallium
___
_
About 1.5
_-__.-4 _______________________ __ About 1.5
Vanadium
___.._
About 1.5
Uranium ____________ ___. ______________ __ About 2.0
Ruthenium
Copper ____
Nickel
Cobalt
2,812,233
2,902,514
2,909,542
2,933,475
____________________________ __ About 1.0
__
....
_..__
__
Chem. Abs., vol. 45, 5572(i) (1951).
Martell and Colvin: “Chemistry of the Metal Chelate
Compounds,” 446-49, 468-69 (1952), Prentice-Hall Inc.,
._ About 4.0
About 4.0
Chromium ___________________________ .__ About 4.0
which is chelated with a solid, solvent insoluble poly
1957
1959
1959
1960
OTHER REFERENCES
40
About 2.0
About 3.5
Lewis _______________ __ Nov. 5,
Benneville et al. _______ __ Sept. 1,
Soloway _____________ __ Oct. 20,
Hoover et al. ________ __ Apr. 19,
45
New York.
Martell et al.: Cited, paper No. 2, pages 433-445,
450-467.
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