JPH0140658B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to water-insoluble, hydrophilic resins capable of removing metal ions such as radium from aqueous media. In many industries that use aqueous liquid streams containing metal ions, it is necessary to remove such ions from such streams because they are valuable and/or highly responsible. be. Illustrative industries are those using aqueous liquid streams containing radioactive metal ions, such as radium, such as those using nuclear reactors, hospitals, municipal services, scientific laboratories, and those involved in the mining of valuable metals. be. For example, in the removal of naturally occurring radium and/or barium from public water supplies,
It has become customary to use a variety of water softening methods, including the use of ion exchange softening plants as well as lime softening plants. Removal efficiencies ranged from 70% to about 98% for these methods. Unfortunately, however, workers at such plants that remove radium are exposed to increased levels of radiation. Also, such methods generate significant amounts of radioactive waste, which must be properly stored. In the mining of uranium, it is often necessary to remove and dispose of significant amounts of aqueous fluids containing low-level radioactive nuclear materials such as uranium and radium. The composition of this aqueous liquid is (1)
It can be either acidic or alkaline depending on the particular uranium material being mined, (2) the other minerals present in the mine formation, and (3) the chemical composition of the groundwater itself. During recovery of the desired uranium, undesired radioactive metals are often found to be absorbed into the mine muds, and these muds are sent to the scrap storage area. Unfortunately, water that comes into contact with such areas becomes contaminated with such radioactive materials and must be cleaned of radioactive metals before disposal. Similarly, the accumulation of radioactive materials in other aqueous liquid streams and on the equipment through which they pass poses pressing problems for the handling of such liquid streams and their disposal to a wide variety of industries, e.g. Generated from mining water and hospital waste treatment. In the past, such aqueous liquid streams containing radioactive metals or other metals have been purified with various ion exchange systems. Unfortunately, however, such ion exchange systems are expensive because they must often be regenerated. Moreover, such regeneration also yields aqueous liquids containing radioactive metals or other metals that are often toxic and/or valuable. Alternatively, it has been the practice to precipitate metals from such aqueous streams by the addition of various chemical reagents. The resulting sediment forms sludge at the bottom of the settling basin, thereby creating long-term disposal problems. Since the precipitate is not easily cleared, large facilities are required to facilitate proper disposal of the precipitate. Unfortunately, these methods lack specificity for the removal of the metal ions desired for removal. As a result, metal ions that do not require treatment, such as sodium, calcium and magnesium, which are often present in large quantities in such aqueous liquid streams, must be handled as well. In the case of ion-exchange systems, the ion-exchange system is quickly saturated with metal ions that do not require such treatment, and regeneration is much faster than would be required in the absence of such treatment-free metal ions. It must be done with great care. U.S. Patent No. 2,961,399 (Alberti, November 22, 1960)
Japanese Patent) and No. 4054320 (Learmont,
As stated in the patent issued October 18, 1977,
It is well recognized that various forms of barium, particularly barium sulfate, are relatively effective in removing many metals, particularly radium, and other metals such as strontium, cerium, ruthenium and antimony from aqueous media. Unfortunately,
These methods often produce large amounts of sludge containing radioactive or other metals that must be treated or cleaned. In view of the above-mentioned shortcomings of the prior art techniques for removing radioactive substances from aqueous media, it is desirable to remove metal ions, in particular radioactive and/or toxic metal ions, from aqueous media and yet remove radioactive and/or toxic metal ions during the treatment. ) It would be highly desirable to provide an effective means of reducing the amount of metal ions in treated aqueous media to very low levels without producing substantial amounts of toxic waste. The present invention provides that the microparticulate particles are (1) a porous matrix of a water-insoluble, hydrophilic, normally solid organic polymer having a large number of suspended anionic moieties;
comprising a water-insoluble inorganic compound capable of removing metal ions from an aqueous medium dispersed in the matrix, and wherein the particles are capable of removing a substantial portion of the metal ions from the aqueous medium when contacted with the aqueous medium; fine granules for removing metal ions from an aqueous medium, characterized in that they are permeable to the passage of metal ions from said aqueous medium under conditions such that they are retained in said matrix; It is something that provides something. The present invention also provides a method for making an adsorbent resin for removing and retaining metal ions from an aqueous medium, comprising: (1) a water-insoluble, hydrophilic polymer having a pendant anion moiety in the interior region of the particle; (2) contacting the microparticles with an aqueous solution of a compound of a similar metal under conditions such that a salt is formed between the metal and the desired portion of the pendant anion moieties in the internal zone; The particles are exposed to a reactant such that (a) the reactant enters the internal region and reacts with the analogous metal to form a water-insoluble compound capable of removing the desired metal ion from an aqueous medium; A method for producing an adsorbent resin, characterized in that the particles containing a water-insoluble compound obtained in this way are brought into contact under conditions such that they are permeable to the movement of metal ions into the internal region of the particles. This is what we provide. In yet another aspect, the invention is characterized in that the granules described above are brought into contact with an aqueous liquid under conditions such that the metal ions pass into the interior area of the resin particles and are thereby removed from the aqueous liquid. A method for removing metal ions from an aqueous liquid is provided. Surprisingly, the adsorbent resins of the present invention are much more efficient at removing specific metal ions from aqueous media than prior art particulate adsorbents. "More efficient" means that the resin is capable of removing and retaining greater amounts of specific metal ions and reduces the concentration of such specific metal ions in the aqueous medium to a lower level than is possible with prior art adsorbents. This means that it can be reduced to . The substantial ability of such adsorbent resins to remove and retain specific metal ions from aqueous media that also contain other metal ions is also surprising. Finally, the adsorbent resin is easy to handle and is easier to dispose of than prior art adsorbents. The adsorbent resins of the present invention are particularly useful for the removal of radioactive divalent radium ions from aqueous effluents of uranium mining operations, particularly at low levels such as 2 to 1000 picocuries/radium ions. Other uses of the resins of the present invention include those requiring the removal of radium from leach solutions of various mining processes, as well as from uranium scrap streams, and for removing cations from aqueous liquids. This includes a wide range of applications that require dense resins. An example of such an application is the treatment of concentrated solutions, such as concentrated sugar solutions, by conventional downflow or upflow techniques. Also, more efficient operation can be achieved by using fluidized bed ion exchange methods using these dense resins. The hydrophilic polymer forming the porous matrix of the granules is suitably any normally solid, water-insoluble organic polymer having a sufficient number of pendant anionic moieties to enable ion exchange from the aqueous medium. It is something. The main skeleton of this polymer is
It is not particularly critical as long as the polymer containing the anionic moiety is water-insoluble. Therefore, although the polymer can be phenolic, polyethylenic, including styrenic and acrylic polymers, and others capable of cation exchange, cross-linked styrenic polymers are preferred. The type of anionic moiety included in the polymer is one that exchanges metal ions from the aqueous medium. Typically, suitable anionic moieties include sulfones, carboxylic acids and phosphones, with sulfones being preferred. The concentration of anionic moieties in the polymer is sufficient to ensure the presence of such anionic moieties in the interior regions of the particles and to enable the polymer to undergo cation exchange from the aqueous medium. Preferably, the concentration of anionic moiety is from about 1 to about 12 milliequivalents per gram of polymer (meq/g), and in some cases preferably about
It is 4.7 to about 5.3 meq/g. Particularly preferred as polymers in the practice of this invention are polymerizable monoethylenically unsaturated monomers or mixtures of such monomers and cross-linking agents copolymerizable therewith, typically polyethylenically unsaturated monomers such as divinylbenzene. It is a cross-linked polymer produced by addition copolymerization with monomers. Suitable polymerizable monoethylenically unsaturated monomers, cross-linking agents, catalysts, polymerization media and methods for preparing this cross-linked addition copolymer in particulate form are well known in the art. Examples of such techniques include U.S. Pat. No. 2,960,480;
No. 2788331 (which discloses a method for making gel-type cross-linked polymers) and U.S. Pat.
No. 363,735 and No. 3,549,562 (which also disclose methods for making porous resins, often referred to as macroporous resins). Among the well-known monoethylenically unsaturated monomers for polymerization, monovinylidene aromatics such as styrene and monoalkyl-substituted styrenes (such as vinyltoluene,
Ethylvinylbenzene) and vinylnaphthalene are preferred, with styrene being particularly preferred. Preferred cross-linking agents include polyvinylidene aromatics such as divinylbenzene, divinyltoluene, divinylxylene, divinylnaphthalene, trivinylbenzene, divinyldiphenyl ether, divinyldiphenylsulfone and isopropylvinylbenzene; ethylene glycol dimethacrylate and divinylsulfide. are included, with polyvinylidene aromatics especially divinylbenzene being most preferred. As mentioned above, this matrix polymer has a large number of anionic moieties. Preferably such anionic moiety is a sulfonic acid moiety typical of any of the common sulfonic acid resins utilized commercially for exchanging cations from aqueous solutions. Typically this preferred resin is in the sodium salt form or the acid form. Examples of such exchange resins are obtained by sulfonating resinous condensation products of formaldehyde and phenolsulfonic acid, formaldehyde and phenols or other monohydric or polyhydric phenols. Cation exchange resins are sulfonated resinous copolymers of monoethylenically unsaturated and polyethylenically unsaturated monomers, such as styrene and divinylbenzene. Particularly preferred cation exchange resins include from about 1 to about 20% by weight, preferably from about 2 to about 20% by weight.
It is a sulfonated copolymer of styrene cross-linked with about 4% by weight divinylbenzene. Such particularly ^preferred resins have approximately
It has a sufficient concentration of sulfonic acid moieties to have a dry weight capacity in the range of 4.5 to about 5.2, particularly about 4.8 to about 5.1 meq H ⁺ /g. Such particularly preferred resins also have a water retention capacity in the range of about 35 to about 90, particularly about 50 to about 75% water by weight in the wet form of the resin. Examples of such particularly preferred resins are sodium, hydrogen or lithium type and macroporous acrylic gel resins, typically in the form of spherical beads. As previously mentioned, the matrix polymer containing anionic moieties is in particulate form. Preferably, such particulates have an average particle size in the range of about 10 to about 1200 microns, particularly about 500 to about 1200 microns. The particles of such granules are porous and allow the migration of metal ions from the aqueous medium into the interior regions of the granules. For example, such resins preferably have an average pore size ranging from about 10 to about 2000 angstrom units, particularly from about 20 to about 100 angstrom units, and from about 0.005 to 1 g wet resin (containing about 75% water by weight). Approx. 0.15m ² especially approx. 0.005
It is micropore with a surface area of ~0.1 ^m2 . Suitable matrix polymers with anionic moieties other than sulfonic acids, such as carboxylic acids and phosphonic acids, and methods for making such materials are described in "Ion-Exchange", Helferich, Mc Graw-
Described in Hill (1962). Water-soluble compounds of similar metals suitable for use in the practice of this invention are those in which (1) the compound is sufficiently soluble that an aqueous solution converts the resin to its similar metal form by ion exchange; 2) reacts with the anionic portion of the polymer to provide a salt of the desired portion of the anionic portion of the interior region of the granule with the metal; and (3) is similar to the particular metal ion to be removed from the aqueous medium. contains metals. For the purposes of the present invention, if the metal forms a water-insoluble compound capable of removing the specified metal from aqueous solution and retains the specified metal ion during continued contact with the aqueous medium, The metal is similar to the specific metal ion to be removed from the aqueous medium. Preferably, the metal analog is chemically similar to the particular metal as predicted by the Periodic Table of the Elements. To explain further, similar metals are from the same group of the periodic table of elements as the specific metal ion, and more preferably from a period adjacent to the period of the specific metal ion. For transition metals and internal transition metals, analogous metals can be elements that are adjacent to or near the particular metal in the same period of the Periodic Table of the Elements. For example, if radium is the specific metal ion, the similar metal is preferably barium, with strontium and calcium being less preferred. When gold is the specific metal, the analogous metal is preferably silver. Examples of such water-soluble compounds include barium hydroxide and water-soluble salts of barium such as barium chloride, barium bromide, barium cyanate and barium acetate, with barium hydroxide being particularly preferred. Other suitable water-soluble compounds include strontium acetate, strontium chloride, calcium chloride, silver nitrate, calcium acetate and thorium nitrate. Reaction reagents suitably used in carrying out the present invention are (1)
(2) ability to react with the analogous metal cation moiety and remove the specific metal cation from the aqueous liquid; It is a compound that can form certain water-insoluble compounds. This compound is a sufficiently water-insoluble compound that has sufficient affinity for the specific metal ion to retain the specific metal ion in the adsorptive resin particles after repeated contact with an aqueous liquid. . Preferably, the water-insoluble compound is such that it dissolves in water 1 in an amount of 2 g or less, most preferably 0.1 g or less. The agent that reacts with the metal-type wetting resin is preferably a strong acid, such as sulfuric or hydrochloric acid, or a moderate acid, such as phosphoric acid, which reacts with similar metals to form the desired water-insoluble compound. When the analogous metal is barium, the reactants are sulfuric acid, iodic acid, gaseous sulfur trioxide, and similar acids known to react with barium to form water-insoluble salts in highly acidic media. It is.
Slightly concentrated sulfuric acid, such as 5M to 16M _{H2SO4 ,} is more preferred, and 6M to _{10M H2SO4} is most preferred.
When the analogous metal is silver, the reactant is preferably hydrochloric acid or other acid that reacts with silver to form a water-insoluble compound. In the production of water-insoluble polymer granules in the form of analogous metal salts, the polymeric granules containing anionic moieties in acid or sodium form are immersed in an aqueous solution of a compound of an analogous metal, such as barium hydroxide, calcium chloride or silver nitrate, or alternatively Wash with the aqueous solution. The concentration of the aqueous solution of the analogous metal compound is not particularly critical, as long as a suitable degree of exchange between the analogous metal and the anionic moieties of the water-insoluble polymer is obtained, especially in the interior areas of the granules of the water-insoluble polymer. . Preferably, the concentration of water-soluble compounds of similar metals is from about 0.1 to about 20% by weight in the aqueous solution, most preferably from 1 to 10% by weight. In general, the methods used to effect the exchange of resins into analogous metal salt forms conform to conventional techniques of cation exchange, including exchange of analogous metal ions from aqueous solutions. Conversion of similar metal salt type resins to adsorption resins containing water-insoluble salts of similar metals (useful for removing and retaining specific metal ions from aqueous solutions) preferably involves converting the salt moieties of similar metals and anionic moieties into adsorbent resins containing water-insoluble salts of similar metals. This is accomplished by passing the reactive reagents throughout the interior regions of the containing particles. To ensure penetration of the reactant into the interior areas of the polymer particles, it is critical that the concentration of the reactant be sufficient to overcome the Donnan potential specific to the particular polymer and anionic moiety involved. It is true.
If such concentrations are not sufficient, it is observed that the formation of water-insoluble compounds of similar metals occurs only on the surface of the particles and not at all in the internal regions of the particles. Such closed resins are generally undesirable for the practice of this invention. Preferably, when barium is the analogous metal, the concentration of sulfuric acid used to treat the barium salt form of the most common cation exchange resins derived from copolymers of styrene and divinylbenzene is about 40
to about 90% by weight, preferably from about 45 to about 65% by weight. After forming a water-insoluble compound within the resin particles,
It is generally preferred to use deionized water to wash the resin to remove residual reaction reagents or other undesirable products. In this washed form, the resin is ready for use to remove specific metal ions from aqueous solutions. The adsorptive resin consists of particles of a porous matrix polymer having a large number of anionic moieties and dispersed within the matrix particles a water-insoluble compound capable of removing and retaining metal ions from an aqueous medium. . Generally, the water-insoluble compound increases the ability of the resin to remove and retain desired specific metal ions from an aqueous medium by at least 10% by weight, and preferably by at least 100% by weight, over a matrix polymer that does not contain the water-insoluble compound. present in sufficient quantities. Preferably, the adsorbent resin contains from about 1 to about 90% by weight, most preferably from about 5 to about 50% by weight, of water-insoluble compounds. In practice, a liquid aqueous medium containing certain metal ions such as barium, radioactive strontium, cerium, radioactive cobalt, ruthenium, gold or other noble metals, thorium, arsenic, cadmium, chromium, silver, lead and antimony is added to the granules of the present invention. and contacting under conditions such that the specific metal ions are entrained in the interior areas of the granules, thereby removing the specific metal ions from the aqueous solution and retaining them in the granules. Typically, such contact is similar to that used for cation exchange from aqueous solutions. The concentration of specific metal ions in the aqueous solution to be treated is approximately 1 trillion parts by weight of the solution.
0.001 parts to about 10,000 parts per million copies, preferably 1
It can range from about 0.01 parts per trillion to about 1000 parts per million. The following examples are provided to illustrate the invention. All parts and percentages are by weight unless otherwise specified. Example 1 The resin used was 2% cross-linked wet with a particle size ranging from 500 to 1200 microns, a dry weight capacity of 5.1 meq H ⁺ /g, a water holding capacity of 75.9% and a density of 1.13 g/ml. It was the acid form of the sulfonated styrene/divinylbenzene copolymer cation exchange resin. 0.3N of Ba in 200g of this resin
(OH) ₂ was added to convert the resin quantitatively to the barium form and to provide a small excess of Ba(OH) ₂ . This barium type resin has 42% water holding capacity and
It had a density of 1.29 g/ml. After conversion to the barium form, the resin was contacted with a small amount of the acid form of the resin to remove excess Ba(OH) ₂ . The barium-type resin was then washed with deionized water and dehydrated by filtration. This dehydrated barium type resin (barium resin) is covered with this resin and the H ₂ SO ₄ concentration is ≧
Enough 6M- _H2SO4 was added to keep it at _5M - _H2SO4 (approximately 80% of the water in _the barium resin is released into solution). The barium resin initially contracted by 20-40 volumes and swelled to a slightly larger volume than the barium resin in 3-5 hours. Analysis of the resulting resin showed that the resin was converted to the acid form and BaSO ₄ was formed in the internal zone. Excess sulfuric acid was removed by filtration. The filtered resin was washed with deionized water. At that time, the resin expanded to a volume slightly larger than the original volume of the acid form. The resulting adsorbent resin has a density of 1.216 g/ml, a dry weight capacity of 2.9 meqH ⁺ /dry g and a dry weight capacity of 65
% water holding capacity. Fill a column (300 cm x 5.08 cm diameter) with 2,500 g of the obtained adsorbent resin, and set the wet static bed height.
It was set to 76cm. An aqueous medium containing 25 picocuries of radium ions per column was passed upwardly through the two columns connected in series at a rate of 26/min for 7 months. The eluate from the column was periodically tested for radioactivity, and 2
It was found to contain less than picocury of radium. The adsorbent resin was then analyzed and found to contain the appropriate amount of radium ions. Example 2 Using a cation exchange resin similar to Example 1 but with a water holding capacity of 67.9%, a cross-linking content of 4%, and a density of 1.11 g/ml, the adsorptive resin was prepared as in Example 1. manufactured by the method. Tazushi 6M−
8M _{- H2SO4} was used instead of _{H2SO4 .} The resulting adsorbent resin had a density of 1.301 g/ml, a water holding capacity of 54.6% and a dry weight capacity of 3.1 meq H ⁺ /g. This adsorbent resin was tested for its ability to remove radium by the method of Example 1, and was found to have an effective ability to remove barium. Example 3 Following the method of Example 1, particle size ranging from 500 to 1200 microns, dry weight capacity (DWC) of 5.18 meq H ⁺ /g, water holding capacity (WRC) of 77.3% and
A 2% cross-linked sulfonated styrene/divinylbenzene copolymer cation exchange resin with a density of 1.09 g/ml was contacted with a sufficient amount of 0.5N-Ba(OH) ₂ to quantitatively convert the resin to the barium form. did. This barium resin is then covered with resin.
Contact was made with a sufficient amount _{of 8-10M H2SO4} to maintain the concentration _{of H2SO4} at ≧5M _H2SO4 . The resulting adsorbent resin was washed with deionized water to remove excess acid, and 30 g of this resin was tested for DWC,
WRC, barium %, wet volume capacity (WVC) [meq H ⁺ per ml actual volume of resin] and density were determined. The adsorbent resin was cycled an additional five times using the method described above and tested for DWC, WRC, barium %, WVC, and density after each cycle. The results of these tests are shown in Table 1. As can be seen from the data in this table, the barium concentration increases with each additional cycle. 【table】

Claims (1)

[Scope of Claims] 1. Particles of a fine particulate material comprising (1) a porous matrix of a water-insoluble, hydrophilic, normally solid organic polymer having a large number of suspended anionic moieties and (2) dispersed within the matrix. a water-insoluble inorganic compound capable of removing metal ions from an aqueous medium, and wherein the particles, when brought into contact with the aqueous medium, remove a substantial portion of the metal ions from the aqueous medium to form the above-mentioned matrix. Fine particulates for removing metal ions from an aqueous medium, characterized in that they are permeable to the passage of metal ions from said aqueous medium under the conditions in which they are retained therein. 2. The amount of water-insoluble compounds in the fine granules increases the ability of the granules to remove and retain metal ions from the aqueous medium by at least 10% by weight compared to the ability of the polymer without the water-insoluble compounds. The granules of claim 1 in an amount sufficient to increase the amount of granules. 3. Claim 1, wherein the polymer is a cation exchange resin and the water-insoluble compound is a salt of an acid with a metal similar to the metal ion to be removed from the aqueous medium.
The granular material according to item 1 or 2. 4. The granular material according to claim 3, wherein the cation exchange resin is a sulfonated copolymer of styrene and divinylbenzene, the salt is a water-insoluble barium compound, and the metal ion is divalent radium. 5. The granular material according to claim 4, wherein the cation exchange resin is a macroporous resin. 6. A method for producing an adsorbent resin for removing and retaining metal ions from an aqueous medium, the method comprising: (1) preparing microparticles of a water-insoluble, hydrophilic polymer having a suspended anion moiety in the interior region of the particle; (2) contacting an aqueous solution of a compound of a metal with a salt of the metal and a desired portion of the pendant anion moieties in the interior zone under conditions that result in the formation of a salt; and (2) reacting the particles in the resulting metal salt form. a reagent; (a) the reactive reagent enters the internal region and reacts with the analogous metal to form a water-insoluble compound capable of removing the desired metal ion from the aqueous medium; and (b)
Preparation of the adsorbent resin as described above, characterized in that the particles containing the water-insoluble compound thus obtained are brought into contact under conditions such that they are permeable to the movement of metal ions into the internal area of the particles. Law. 7 The polymer is a sulfonated copolymer of styrene and divinylbenzene, the water-soluble salt is barium hydroxide, and the reactant is
7. The method of claim 6, wherein the sulfuric acid is at a concentration of 16 molar. 8 The particles of the fine particulate material are composed of (1) a porous matrix of a water-insoluble, hydrophilic, normally solid organic polymer with a large number of suspended anionic moieties, and (2) dispersed within the matrix, the metal is removed from the aqueous medium. The particles are comprised of water-insoluble inorganic compounds capable of removing ions, and such that when the particles are brought into contact with an aqueous medium, a substantial portion of the metal ions are removed from the aqueous medium and retained in the matrix. A fine particulate material for removing metal ions from an aqueous medium, which is permeable to the passage of metal ions from the aqueous medium under conditions, is introduced into the aqueous medium and into the interior area of the resin particles. 1. A method for removing and retaining metal ions from an aqueous liquid, characterized in that the contacting is carried out under conditions such that metal ions are removed from the aqueous liquid.