JP3087905B2 - Adsorbent and method for removing suspended impurities - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an adsorbent for removing suspended impurities and a method for removing suspended impurities. In particular, the present invention relates to an adsorbent for adsorbing and removing suspending impurities present in water to be treated in an ultrapure water production apparatus for semiconductor industry or a condensate purification apparatus of a steam power plant, and a suspension using the adsorbent. The present invention relates to a method for adsorptive removal of an impurity.

[Conventional technology]

In the steam power plant, it is necessary to keep the inside of the boiler clean at all times, so the condensate returning from the turbine condenser into the boiler is purified by a condensate desalinator, and after being highly purified,
Water is supplied as cooling water to the boiler. This condensate demineralizer is a so-called mixed-bed type demineralizer in which a cation exchange resin and an anion exchange resin are mixed and filled. Metal oxide fine particles) by ion exchange and adsorption / filtration to purify condensate.

Such accumulation of suspended solids can cause increased system pressure, reduced flow rates, and reduced efficiency of power generation equipment.
Thus, by reducing the level of impurities, especially the level of suspended solids, a good reflux loop can be maintained.

JP-A-1-174998 discloses the removal of suspended impurities from the main cooling water of a boiling water reactor (BWR) by using a mixed bed ion exchange resin having a low crosslinking agent (divinylbenzene) content of 3 to 7.5%. is suggesting. The publication states that low-crosslinking resins have larger micropores than higher-crosslinking ion-exchange resins, and are relatively softer and more elastic, and because of these features, they have a lower degree of crosslinking. He states that the cladding can be more effectively removed from the water.

JP-A-63-59355 discloses that a cation exchange resin is oxidized in a dilute solution of sodium sulfate at a current of 2 A for 3 to 4 hours using a platinum electrode. The oxidized resin has been reported to be effective in removing fine and amorphous particles in condensate generated by corrosion of thermal or nuclear power plant piping or other structural materials.

U.S. Pat. No. 4,564,644 describes an ion exchange resin having a shell / core structure. These have the same structure as the resin used in the present invention. These are stated to be more effective under harsher conditions than conventional gel-type resins, and especially in condensate purification and mining operations. However, this patent does not show their special ability to remove colloidal iron to an extent previously unattainable, and does not disclose any particular utility for decladding during BWR condensate. Not mentioned.

[Problems to be solved by the invention]

In the method using the above granular ion exchange resin,
Removes impurities from ion-exchange resin by constantly regenerating chemical components and physical backwashing by ion-exchange-adsorbed or trapped ion-exchange resin on ion-exchange resin, and constantly recovering water. The maintenance of the cleanliness of the desalinator is performed.

On the other hand, among the steam power generation facilities, the BWR power generation facilities have recently been strengthening the separation effect of metal oxides among the removal effects of ionic components and metal oxides from condensate water, and Attempts are being made to reduce the amount of metal oxides brought into the reactor and to reduce the exposure of workers during periodic inspections of the plant. in this way,
As the demand for the effect of removing metal oxides required for cooling water of nuclear power plants has become more sophisticated, the conventional method using granular ion exchange resins has a small effect of separating and removing metal oxides. It was found that such a request could not be met.

The present inventors have conducted intensive studies for the purpose of developing means capable of coping with such a current situation, and have completed the present invention.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention relates to a method for producing suspended impurities (mainly colloidal substances such as metal oxides) present in water to be treated in an ultrapure water production apparatus for semiconductor industry or a condensate purification apparatus for steam power generation equipment. When the organic polymer adsorbent composed of a granular or powdered cation exchange resin and / or an anion exchange resin is adsorbed and removed by using a scanning electron microscope and inspected in a visual field of 500 to 200,000 times, Provided is an adsorbent for removing suspended impurities, which can confirm that the surface layer of the adsorbent has a granular binding structure.

The above adsorbent preferably has a granular binding structure in which the apparent unit granule size of the granular fine particles is observed and observed by a scanning electron micrograph, and is 0.1 mm.
~ 1.0 μm, resulting in the appearance of collectively binding, and the adsorbent has a diameter of 0.
A spherical adsorbent having a diameter of 2 to 1.2 mm, more preferably a vacuum adsorbent. The particle diameter of the spherical particles is not always limited to a continuous one having a so-called Gaussian distribution, and includes a single or uniform particle diameter.

The spherical particle adsorbent generally has grooves on its surface, and the grooves have a turtle-like and / or scaly pattern. In addition, the turtle-like and / or scale-like pattern is 1 to 50μ, respectively.
It has a unit area of m ² , exhibits an irregularly shaped surface structure, and each unit has a turtle-like and / or scale-like pattern,
Adjacent surface states are present via grooves having a width of 0.1 to 5 μm and a depth of 0.1 to 5 μm, and the total length of the grooves is 100 to 1000 mm / mm ² per unit area.

Further, the spherical particle adsorbent has an effective specific surface area of 0.02 to 1.00 m ² / g-dry adsorbent, which is measured from krypton and / or a gas adsorption amount equivalent to krypton.
It has a double structure having a skin layer of 0.1 to 10 μm or more.

Further, when the spherical particle adsorbent is powdered, a powdery adsorbent is obtained.

When a packed bed and / or a filtration bed are formed using these adsorbents, a suspended impurity removing material characterized by enhancing and improving the ability to remove suspended impurities in ultrapure water or condensed water can be obtained.

In the method for adsorbing and removing suspending impurities present in the water to be treated in an ultrapure water production device for semiconductor industry or a condensate purification device for a steam power plant, the treatment water is adsorbed and removed according to the present invention. The contact with the agent makes it possible to very effectively remove the suspended impurities. That is, when the adsorbent of the present invention is used, the surface and / or surface structure of the adsorbent used is higher than that of the ion-exchange adsorbent used in the conventional mixed-bed desalter. It has a structure that selectively adsorbs and removes substances, has a high affinity for metal oxides, and has a large effect of separating and removing metal oxides. Treated water can be provided.

For example, when removing colloidal iron contained in condensate of steam power generation equipment, when using a conventional resin in a mixed bed, about 75 to
80% sustained removal is achieved, while about 95% sustained removal is achieved using the adsorbents of the present invention.

In the method of removing a suspension according to the present invention, a conventionally known apparatus can be used, and conventionally known process conditions can be applied. For example, an apparatus using a mixed bed type column shown in FIG. 4 is filled with the adsorbent according to the present invention to treat water to be treated. At that time, the water flow velocity varies depending on the type of the water to be treated, but is preferably selected in the range of 20 to 130 m / h, more preferably 90 to 120 m / h. Under these conditions,
For example, processing is performed for 1 to 10 cycles in one cycle of 10 hours to 100 days. The temperature of the water to be treated is suitably from 10 to 60 ° C.

The cation exchange resin and anion exchange resin useful in the present invention comprise gel-type copolymer beads having a core / shell structure and are produced by a process comprising the following steps: (a) a plurality containing free radicals; Forming a polymer matrix in a continuous phase; (b) allowing the matrix to absorb a monomeric material comprising at least one monomer and no free radical initiator;
Subjecting the monomeric material absorbed by the matrix to conditions in which free radicals in the matrix catalyze the polymerization of the monomeric material in the matrix; and (c) the resulting copolymer A step of providing a functional group to the beads.

Preferably, the cation exchange resin (component 1) or the anion exchange resin (component 2), more preferably the copolymer beads used for both, are copolymers comprising at least partially monovinylidene aromatic and divinylidene aromatic monomers Including beads. In particular, copolymer beads containing a copolymer comprising at least partially styrene and divinylbenzene (DVB) are preferred. Most preferably, the copolymer beads used in the present invention comprise only monovinylidene aromatic monomers and divinylidene aromatic monomers,
More preferably, it consists only of styrene and DVB.

Preferably, the functionalized copolymer beads of Component 1 used in the present invention have a crush strength of at least about 700 g / bead, more preferably about 800 g / grain. Preferably, the functionalized copolymer beads of Component 2 have a crush strength of at least about 500 g / bead, more preferably about 600 g / particle.

Preferably, the functionalized copolymer beads of components 1 and 2 are contacted with 8 moles of hydrochloric acid and 8 moles of sodium hydroxide alternately 10 times (both acid and base contact are one cycle). Less than 15% in the number of beads, more preferably 10
% Less than the osmotic pressure.

Preferably, in the present invention, component 1 is contacted with a strong acid, such as sulfuric acid, before contacting the condensate with H
Mostly converted to type. Similarly, component 2 is
If not, preferably before contact with the condensate, a strong base such as, for example, sodium hydroxide,
It was mostly converted to the OH form by contacting component 2.

Components 1 and 2 are preferably mixed in a volume ratio of 3: 1 to 0.5 to 1, more preferably 2: 1 to 1: 2.

In a particularly preferred embodiment, the gel-type copolymer beads, which are the resin source of component 1 or component 2 in the adsorbent, comprise: i) about 0.1, preferably about 0.2 to about 2.0,
Preferably, up to about 1.0 DVB weight percent of a plurality of styrene-
Suspending the DVB copolymer seed particles, ii) allowing the particles to absorb a monomer mixture of styrene, DVB and a radical initiator (free radical), and then initiating a reaction between the absorbed styrene and DVB to produce an initial monomer At least about 20%, preferably about 40%, more preferably about 85%, especially about 90% by weight of the amount is modified into a polymer in the particles, and iii) styrene or styrene is added to the aqueous suspension. And DVB
But containing essentially no polymerization initiator, the second monomer composition is absorbed into the particles, and the polymerization of the second monomer composition is carried out in the particles. By continuously adding them under the conditions catalyzed by

The above polymerization may then be continued until all of the first monomer mixture and essentially all of the second monomer components have been polymerized. Preferably, the first monomer mixture comprises from about 1% by weight, more preferably from about 2% by weight to about 10% by weight.
%, More preferably up to about 8% by weight of divinylbenzene. Also, preferably, the second monomer composition comprises from about 90% by weight, more preferably from about 95% by weight to about 98% by weight.
% Styrene, more preferably up to about 100% by weight.

The water treated in the method of the present invention is, for example, condensate from a boiling water reactor. Also, the condensate may suitably be passed through a mechanical filter, such as a standard porous filter or other similar means, to remove larger particles of suspended solids. However, preferably, the method is performed without a pretreatment such as mechanical filtration. this is,
This is because the very effective action of the mixed bed resin used eliminates the need for mechanical filtration or at least reduces the size of the filtration equipment to be used.

The method of the present invention is based on the use of ion exchange resin beads with a very fine structure, which structure will be referred to hereinafter as "core / shell structure". They are characterized by having high crush strength and osmotic shock resistance when converted to ion exchange resins. The copolymer beads are functionalized to form a strong acid, weak acid, strong base, or weak base ion exchange resin, all of which have improved mechanical properties compared to typical gel-type resins. Show characteristics. Preferably, only strong acid and weak base ion exchange resins are used in the process of the present invention. Representative anionic groups and cationic groups will be described later. The resin retains other desirable features of the gel-type resin, namely, high capacity and high ion selectivity.

As used herein, the term "core / shell structure" means that the polymerized structure of the copolymer beads used in the present invention changes from inside to outside of the beads. The polymerized structure changes slowly from the inside of the bead to the outside, producing beads with a gradient of the polymerized structure along the radius.
Also, the polymerized structure can change relatively abruptly from the center of the radius of the bead to the outside, with a relatively distinct core having one polymerized structure and a second comparison having another polymerized structure. Generate beads with well-defined shells. The rate of change of the polymerized structure of the beads is not particularly important. Thus, as used herein, the terms "core" and "shell" refer to the polymerized structure inside and outside the bead, respectively, and the use of these terms means that the beads used are the polymer inside and outside the bead. Should not be construed as indicating a distinct interface between the polymer and the polymer. When referring to "core polymer" and "shell polymer", it is usually, but not always, to indicate that there is a significant amount of interpenetration of the polymer present in the core and shell, respectively, of the copolymer bead. I want to be understood. Therefore,
The "core polymer" penetrates somewhat into the shell, while the "shell polymer" penetrates somewhat into the core. The terms "core polymer" and "shell polymer" are not intended to identify a particular polymer as a "shell" or "core" polymer, but rather refer to the polymer material in a particular portion of the bead. It is used to describe the method.

The core / shell structure of the copolymer beads can be found using various known techniques to determine the structure of the polymeric material. In general, one or more of the following analytical techniques are suitable for determining the core / shell structure of the copolymer beads used in the present invention. Dynamic thermal analysis, differential thermal analysis, osmium stain technique, measurement of refractive index of core and shell of copolymer beads, conventional transmission electron microscopy, analytical transmission electron microscopy, scanning electron microscopy And other techniques. Further, the beads of the present invention often exhibit a symmetric distortion pattern that is detectable by examining the beads under polarized light. The core / shell structure of the copolymer beads of the invention can often be easily identified by optical inspection of the beads at 1 × or low magnification, where the core is a region of a different color than the shell. That is, it is observed as a darker or lighter area.

When functional groups are provided to form the ion exchange resin, the core / shell structure of these beads is often observed by immersing the dried beads in water and determining the percentage of hydration of the beads. . Typically, the penetration of water into the shell portion of these beads is faster than the penetration into the core.

Preferably, the beads have a shell that contains an average percentage of crosslinking monomer equal to or less than the average percentage of crosslinking monomer in the core. This type of bead has a shell that is softer (i.e., less brittle and more elastic) than the core, so that the bead can maintain its shape and integrity, and the bead is subjected to external stress or pressure. Sometimes the energy can be distributed throughout the structure. By dispersing the energy throughout the structure, the crush strength and osmotic shock resistance of these heterogeneous beads are greatly enhanced.

Also, in addition to the difference in crosslink density between the core and the shell, preferably the polymer in the shell has a higher molecular weight than the polymer in the core. The high molecular weight of the shell polymer imparts mechanical strength to the beads and increases osmotic shock resistance.

The copolymer beads used herein generally exhibit an effective crosslink density higher than the average percentage of crosslink monomers actually used in core and shell preparation. The effective crosslink density is John
Kirk-Othme, published in 1966 by Wiley and Sons
RMWheaton and A.R.
Determined from the increase in volume percent after swelling the beads with toluene using a graph such as that described in the "Ion Exchange" section by H. Seamster. In general, the beads of the present invention exhibit an effective crosslink density of about 1.5 to 5 times, as predicted from the average proportion of crosslinking monomers used for core and shell polymerization.

The copolymer beads used in the present invention exhibit excellent crush strength and, when converted to an anion exchange resin or a cation exchange resin, exhibit excellent osmotic shock resistance. The crush strength of the copolymer beads is excellent, whether used as an anion exchange resin or as a cation exchange resin. However, the mechanical and osmotic properties of the resin will vary somewhat depending on the type and amount of active ion exchange groups involved. The crush strength of the copolymer beads is generally lowest when fully aminated to form an anion exchange resin, and the crush strength of the fully aminated beads is herein referred to as the copolymer beads. Used to compare the crush strength of The term "fully aminated" means that at least 75%, preferably at least 90%, more preferably at least 95% of the repeating units in the bead to which amino groups can be attached have amino groups. I do. The degree of amination is often indicated by the ion exchange capacity of the aminated resin. A fully aminated gel-type ion exchange resin can have its capacity affected by other factors such as the degree of crosslinking, the specific polymer present in the resin and the porosity of the resin,
Generally, it indicates a volume per dry resin weight of at least 4.0 meq / g, and usually at least 4.2 meq / g.

As used herein, the term "crush strength" refers to the mechanical load required to break an individual resin bead, which is given as the average of 30 tests. The gel-type beads used herein, fully aminated to form an anion exchange resin, have a crush strength of at least about 400 g per bead, preferably at least about 500 g, particularly preferably at least about 600 g per bead. In contrast, the first gel-type copolymer beads used, when fully aminated to form an anion exchange resin, exhibit a crush strength of less than 500 g per bead. When sulfonated to form a strong acid cation exchange resin, the polymer beads used in the method of the present invention generally comprise at least about 500 g, preferably about 700 g, particularly preferably at least about 800 g per bead. Shows the crushing strength of

The functionalized beads used herein (ie, beads having an active ion exchange group attached) also exhibit excellent osmotic shock resistance. Osmotic shock resistance for the purposes of the present invention is measured by contacting a predetermined amount of functionalized beads with 8 M HCl and 8 M NaOH alternately 10 times, where each treatment is deionized water. This is done after backwashing with. One cycle of the treatment comprises (a) immersing a predetermined amount of beads in 8M acid for 1 minute, (b) washing with deionized water until the washing water becomes neutral, and (c) washing the beads with 8M acid. For one minute, and then (d) washing the beads with deionized water until the wash water is neutral. Here, alternate treatment with 8M HCl and 8M NaOH is referred to as a repeated cycle test. The osmotic shock resistance of the beads is measured by the number of beads left unbroken after 10 cycles of testing. Typically, at least 85% of the functionalized beads remain undamaged after 10 cycles of osmotic impact testing. Preferably, at least 90%, more preferably at least 95% of the functionalized beads remain unbroken after 10 cycles of osmotic impact testing.

Furthermore, ion exchange resins consisting of copolymer beads having a core / shell structure, when fully aminated or sulfonated, exhibit ion exchange capacities comparable to conventional gel-type resins. However, ion exchange resins having somewhat lower ion exchange capacity can be prepared from the copolymer beads of the present invention by intentionally functionalizing the beads to a greater extent. However, the capacity per dry resin weight of the anion exchange resin used in the present invention is generally at least about 2.5 meq / g, preferably at least 3.5 mq / g.
eq / g, more preferably at least 4.0 meq / g. The cation exchange resin used in the present invention generally exhibits a capacity per dry resin weight of at least 2.5 meq / g, preferably at least 4.5 meq / g, more preferably at least 5.0 mq / g.
Indicates eq / g.

The copolymer beads used in the present invention may be prepared in a suitable size and have an average diameter of from 50 microns to 2000 microns, preferably from 200 microns to 1200 microns. The beads are of the so-called "gel" or "micropore" type. Further, the core of the beads as used herein comprises a polymeric material that is water-soluble when the ion exchange group is attached to it, all or a portion of which form pores or channels within the bead. Therefore, it may be extracted. The preparation of such gels and extractable seed beads is described in detail below.

The copolymer beads preferably form cross-linked free radicals containing a matrix (hereinafter, referred to as a free-radical matrix), and the cross-linked free radicals are mixed with a monomer material containing at least one kind of monomer and a core material. Prepared by contacting under conditions such that the free radicals catalyze the polymerization of the monomer to form a copolymer bead having a / shell structure. The polymerization is carried out as a suspension polymerization, wherein the polymer matrix and the monomers to be polymerized are suspended in a suitable suspension medium, which is an aqueous solution containing a suspension stabilizer.

Preparation of the free radical matrix can be performed by a predetermined method. Advantageously, said free-radical matrix is of the in-situ, one-stage or two-stage type, as described below. This “in situ” type free radical matrix preferably has a conversion of the monomer to polymer of at least 20%.
%, Preferably at least 50%, more preferably 50% to
It is produced by suspension polymerization of a monomer mixture containing mono- and polyethylene-based unsaturated addition polymerizable monomers to 80%. The "single stage" free radical matrix comprises:
Preferably, it is prepared by suspending a plurality of seed particles in a continuous phase and swelling the seed particles with a free radical initiator. The "two-stage" free-radical matrix preferably suspends a plurality of seed particles in a continuous phase, and comprises:
Swelling with an initial monomer charge consisting of mono- and polyethylene-based unsaturated monomers and a free radical initiator, the conversion to polymer is at least 20%, preferably 40% to 90%, more preferably about 45%. % To about 95% by polymerizing the monomers in the seed particles.

"In-situ" free radical matrices are preferably prepared by suspension polymerization of monoethylenically unsaturated monomers and polyethylene-based unsaturated monomers to form a crosslinked matrix. The amount of the polyethylene-based unsaturated monomer used is selected so that the seed particles are sufficiently crosslinked so as not to dissolve in the monomer raw material. It is selected below the amount that cannot be absorbed. Generally, the seed particles comprise about 0.2 of the cross-linking monomer.
Prepared using from about 05 to about 12.5 weight percent. The polymerization is performed using a free radical initiator under conditions such that a large number of crosslinked polymer particles are prepared. The polymerization is continued until the monomer has been converted to at least 20%, preferably at least 50%, more preferably from about 50% to about 80% of the polymer. According to the method of the present invention, crosslinked polymer particles are prepared so as to include a predetermined amount of unreacted monomer and a large number of free radicals therein.

In preparing the "single stage" free radical matrix, a suspension of polymer seed particles is formed in the continuous phase. The seed particles preferably comprise a crosslinked addition polymer, but may also comprise a crosslinked condensation polymer such as a phenol / formaldehyde polymer. The seed particles are cross-linked in an amount that does not dissolve in certain types and in certain amounts of monomers used in later stages of the process, but the seed particles absorb free radical initiator and monomer. Is crosslinked below the amount that renders it impossible. Generally, the seed particles are prepared using about 0.05 to 12.5 weight percent, preferably about 0.2 to 2.0 weight percent, of a cross-linking monomer. A free radical initiator that is essentially insoluble in the continuous phase and is absorbed by the seed particles is added to the suspension containing the cross-linked seed particles. When a free radical matrix is formed in this manner, the seed particles that have absorbed the free radical initiator include a "free radical matrix".

Also, the "two-stage" free radical matrix is preferably
A number of polymer seed particles are suspended in a suitable suspending medium, and the free radicals, including the initial monomer charge, are absorbed by said particles and the conversion to polymer is at least about 20-95%, preferably Is prepared by polymerizing the monomers of the initial monomer charge to at least 40%. This two-stage free radical matrix consists of two networks. In this process, the seed is preferably an addition polymer, but may be a condensation polymer such as a phenol / formaldehyde polymer. The seed polymer may be cross-linked or not cross-linked, provided that the seed particles are not dissolved in a certain type and a certain amount of monomer used for the initial monomer charge. Good. Within said broad limits, the amount of crosslinking in the seed particles is selected so that the seed can absorb the desired amount of monomer in the initial monomer charge. Generally, increasing amounts of cross-linking reduce the amount of initial monomer charge that can be absorbed by the seed particles.
Advantageously, the seed particles are prepared using less than about 10 weight percent, preferably about 0.1 to 1.0 weight percent of crosslinkable monomer.

The initial monomer charge used to prepare the two-stage free radical matrix contains both mono- and polyethylene-based unsaturated monomers that when polymerized form a crosslinked polymer. The amount of crosslinkable monomer used herein, when functionalized, is generally sufficient to render the beads insoluble in water, and provide physical integrity and mechanical strength to the beads. Is sufficient. Generally, the initial monomer charge comprises about 0.5 to 25 weight percent, preferably about 1 to 12 weight percent, of crosslinkable monomer. Further, the initial monomer charge is preferably about 0.005.
Contains ~ 2 weight percent free radical initiator.

To reduce the amount of out-of-size particles or "fines", the relative proportions of seed particles and initial monomer charge are:
At least 75 weight percent of the initial monomer charge, preferably essentially all of the initial monomer charge, is selected to be absorbed within the seed particles. The ratio will, of course, vary with the size of the seed particles and the degree of crosslinking within the seed particles. For example, relatively small sized seed particles generally absorb proportionately less monomer than larger particles of similar crosslink density. Similarly, high crosslink density within the seed particles limits the capacity of the particles to absorb monomer. Generally, the seed particles will absorb about 0.5 to 19 times, preferably about 1.5 to 9 times, the weight of the initial monomer charge. The free radical matrix preferably comprises from about 5 weight percent, preferably about 10 weight percent, and most preferably from about 25 weight percent of the resulting copolymer beads.
It comprises 90 weight percent, preferably about 70 weight percent, more preferably about 50 weight percent.

The prepared free radical matrix is suspended in a suitable suspending medium. If a one-stage or two-stage free-radical matrix is used, the preparation of said matrix and the following additives and the polymerization of the monomer raw materials are preferably carried out in a single reaction vessel. Generally, the suspending medium is a liquid in which neither the free radical matrix nor the monomers contacted with it are dissolved. The suspension medium is typically between about 0.1 and 1.5.
It is an aqueous solution containing a weight percent of a suspension stabilizer, but may be an organic compound for the polymerization of water-soluble monomers. Suitable suspension stabilizers include surfactants such as gelatin, polyvinyl alcohol, sodium methacrylate, carboxymethyl methylcellulose and sodium lauryl sulfate, and sulfonated polystyrene. In addition, the suspension contains a polymerization inhibitor, a dispersant, and other materials known to be advantageously used in suspension polymerization of ethylenically unsaturated monomers.

The suspension is contacted with a monomer material comprising at least one ethylenically unsaturated monomer under conditions in which the free radicals contained in the free radical matrix catalyze the polymerization of the monomer material. You. Copolymer beads prepared by this process typically exhibit a core / shell structure. In general, the free radical matrix is primarily in the core of the polymer beads prepared in this process, while the polymer formed from the monomeric sources is generally in the shell of the copolymer beads. However, it is believed that interpenetration occurs between the polymer of the free radical matrix and that derived from the monomer source. Therefore, the interface between the core and the shell is not clear. Preferably, the suspension is heated to a temperature sufficient for the ethylenically unsaturated monomer to initiate free radical polymerization. The monomer feed is added to the heated suspension under conditions where essentially all polymerization of the monomer is initiated by free radicals contained within the polymer matrix. Preferably, the ratio of the weight of the monomer to the total weight of the polymer and the monomer present at any time during the addition of the monomer raw material (instantaneous conversion) is at least 20%,
More preferably at least 50%.

The instantaneous conversion is measured in various ways by the special means of monitoring the reaction, which the practitioner chooses. The reaction is monitored chemically as by taking periodic infrared spectra of the reaction mixture as the reaction progresses and monitoring the conversion of monomeric carbon-carbon double bonds to polymer. Differences in density between unreacted monomer and polymer are also grounds for monitoring the mixture. For example, a reaction mixture containing about 1.35 g of styrene monomer per gram of water has about 0.936 g / c before polymerization.
a density of m ^3, after polymerization (at about 96% conversion) is about 1.04
It has a density of g / cm ³ . The difference in density can be determined by a gravimetric method or, preferably, by Texas Nucl.
Monitored using a nuclear photographic densitometer such as the SG series densitometer sold by ear). More simply, the instant conversion is easily calculated from the heat of polymerization.

The instant conversion is controlled by adjusting the rate at which the monomer feed is added to the suspension. The monomer feed is added continuously or intermittently to the suspension at a constant or variable rate during the polymerization process. The proportion of monomer feed added is preferably set such that the instantaneous conversion at any time during the polymerization reaction is at least 20%, preferably 50%.

The monomer feed contains a proportion of polyethylene unsaturated monomer or consists entirely of monoethylenically unsaturated monomer. Here, the monomers in the monomer material can vary over time in the ratio of cross-linking monomers contained therein, or in the type of monomer used, or both. Advantageously, the monomer feed comprises, on average, a proportion of crosslinkable monomer not greater than the average proportion of crosslinkable monomer in the polymerization matrix. More preferably, a lower proportion of crosslinkable monomer is used in the monomer feed to produce a heterogeneous copolymer bead having a higher proportion of crosslinks in the core and a lower proportion of crosslinks in the shell. .

In order for the polymerization of the monomer in the monomer feed to be essentially completely catalyzed by the free radicals contained in the polymer matrix, the monomer feed is preferably essentially free of initiator. Furthermore, there is essentially no initiator in the continuous phase. Advantageously, one or more free radical inhibitors which are soluble in the continuous phase are used to suppress the formation of free radicals in said continuous phase. Therefore, although there is no intention to restrict the present invention by any theory, the generation of free radicals occurs almost exclusively in the free radical polymer matrix, and the monomer in the monomer raw material has a polymerized structure of the free radical matrix. It is likely that high molecular weight chains that are highly entangled around are easily formed.

Eventually, the monomer feed is added to the reaction mixture, and the reaction mixture is maintained at the polymerization temperature until the polymerization reaction is essentially complete. Preferably, the polymerization temperature is increased from about 20C to about 30C during the final stage of the polymerization reaction to complete the reaction. The resulting polymer beads are recovered by conventional means such as filtration, dehydration, and drying.

The monomers used to prepare the free radical matrix (ie, those used to form the seed particles and the initial monomer charge) and the monomer materials are preferably an ethylene-based suspension polymerizable polymer. It is a saturated monomer. Suspension polymerizable monomers are known in the art and are available from Inters, New York.
Published by Cience Corporation in 1956, Calvin E. Sch
III of "Polymer Processes" edited by ildknecht
Chapters, pages 69-109, E. Trommsdoff and C.
"Polymerization in Suspensio" by E. Schildknecht
n ". Table II of Schildknecht, pages 78 to 81, lists various types of monomers that can be used in the practice of the invention. Such suspension polymerizations Of the possible monomers, of particular interest are styrene, vinylnaphthalene, alkyl-substituted styrenes (especially monoalkyl-substituted styrenes such as vinyltoluene and ethylvinylbenzene) and halogens such as bromostyrene and chlorostyrene. Monovinylidene aromatic compounds such as substituted styrene, polyvinylidene aromatic compounds such as divinylbenzene, divinylnaphthalene, trivinylbenzene, divinyldiphenylether, divinyldiphenylsulfone, methyl methacrylate, ethyl acrylate, various alkylene diacrylates and alkylene diene Α, β- such as methacrylate A water-insoluble monomer comprising an ester of a thylene-based unsaturated carboxylic acid, especially an ester of acrylic acid or methacrylic acid, and one or more of the above-mentioned monomers. Aromatic compounds (especially styrene or mixtures of styrene and monoalkyl-substituted styrenes), polyvinylidene aromatic compounds (especially divinylbenzene), esters of α, β-ethylenically unsaturated carboxylic acids, especially methyl methacrylate or methyl methacrylate Mixtures, especially mixtures of styrene and divinylbenzene or styrene, divinylbenzene and methyl methacrylic acid, are preferably used.

Also useful among the polymerizable monomers here are:
A monomer that forms a solution with a liquid, generally water, in which case the resulting solution is sufficiently insoluble in one or more liquids, generally water-immiscible oils, etc. The body solution disperses in the other liquid to form droplets. Representative of such monomers are U.S. Pat.
Water-soluble monomers that can be polymerized using water-in-oil suspension (ie, inverse suspension) polymerization techniques as described in 2,749, and include ethylenically unsaturated monomers such as acrylamide and methacrylamide. Includes carboxamides, aminoalkyl esters of unsaturated carboxylic acids and anhydrides, ethylenically unsaturated carboxylic acids such as acrylic acid or methacrylic acid. Preferred among the monomers used are ethylenically unsaturated carboxamides (especially acrylamide) and ethylenically unsaturated carboxylic acids (especially acrylic acid or methacrylic acid).

In addition to the ethylenically unsaturated monomers, the one-stage and two-stage free radical matrices may include a crosslinked condensation polymer such as a phenol / formaldehyde resin. In general, the condensation polymer must be able to absorb the free radical initiator, the monomer of the initial monomer charge, and the monomer feed.

The monomer feed may include a different monomer than that used to prepare the free radical matrix.
For example, the monomer feed may include styrene, divinylbenzene, and methyl methacrylic acid, and the free radical matrix may include predominantly a styrene / divinylbenzene polymer. If the free radical matrix is prepared by absorbing a catalyst containing the initial monomer charge onto the seed particles, the seed particles may include a different monomer than the initial monomer charge. Similarly, the polymer composition of the polymer shell can be changed from inside to outside of the shell by changing the composition of the monomeric raw materials during the polymerization process. The polymer contained in the polymer beads used in the present invention can vary widely.

Beads with extractable seeds are preferably highly crosslinked or crosslinked, which are insoluble in the amount and type of monomer used in the preparation of the polymer matrix and initial monomer charge. Prepared using no seed particles, but once the active ion exchange groups are attached, the seed particles become water soluble and can be extracted from the beads when immersed in water. Beads prepared with such extractable seeds form small voids when all or some of the sheets are removed therefrom.

Relatively uniform sized copolymer beads are prepared according to the present invention using uniformly sized seed particles. Uniformly sized seed particles can be obtained by sieving the seed particles or in published European Patent Application 0005619.
No. 0051210 and prepared by preparing the seed particles using a process for producing uniformly sized polymer particles as disclosed in US Pat. Preferably, at least 80% of the seed particles used to prepare the copolymer beads of the present invention are in the range of 0.5 to 1.5 times the weight average particle size of the seed particles.

The size of the copolymer beads of the present invention is preferably about
It ranges from 50 microns to about 2000 microns, more preferably from about 200 microns to about 1200 microns. The control of the size of the beads is mainly achieved by controlling the size of the seed particles used and the amount of the monomer used for crosslinking and the monomer raw material. Seed particles are
In size, they range from very small particles, ie, large particles having a diameter of about 10 microns to 750 microns or more. Preferably, the size of the seed particles is from about 100 microns to about 750 microns in diameter.

The polymer beads are converted to anion or cation exchange beads using techniques well known to those skilled in the art that convert a cross-linked addition polymer of monoethylenic and polyethylene-based unsaturated monomers to a resin.

When preparing a weak base resin from a poly (vinyl aromatic) copolymer such as cross-linked polystyrene beads, the beads are:
Preferably, the active ion exchange group is haloalkylated, halomethylated, more preferably chloromethylated, and subsequently attached to the haloalkylated copolymer. Methods for haloalkylating cross-linked addition copolymers and haloalkylating agents used in the methods are well known in the art. Next, references are shown. U.S. Patent Nos. 2,642,417, 2,960,480, 2,597,
No. 492, No. 2,597,493, No. 3,311,602, No. 2,616,817, and "ion exchange" by F. Helferich issued in 1962 by McGraw-Hill, New York. Typically, the haloalkalization reaction swells the crosslinked addition copolymer with a haloalkylating agent, preferably bromomethyl methyl ether, chloromethyl methyl ether or a mixture of formaldehyde and hydrochloric acid, more preferably chloromethyl methyl ether. Reacting the copolymer with a haloalkylating agent in the presence of a Friedel-Crafts catalyst such as zinc chloride, iron chloride and aluminum chloride.

Generally, ion exchange beads are prepared from haloalkylated beads by reacting the beads with a halogen of a haloalkyl group and contacting with a compound that reacts to form an active ion exchange group. Compounds and methods for preparing ion exchange resins, ie, weak base resins and strong base resins, are described in the art and in U.S. Pat. Nos. 2,632,000, 2,61
No. 6,877, No. 2,642,417, No. 2,632,001, No. 2,992,544
And F. Helfferich described above. Typically, a weak base resin is prepared by contacting a haloalkylated copolymer with ammonia, a primary amine or a secondary amine. Representative first and second
The amines are methylamine, ethylamine, butylamine,
Includes cyclohexylamine, dimethylamine, diethylamine and the like. The weak base ion exchange resin is prepared using trimethylamine, triethylamine, tributylamine, dimethylisopropanolamine, ethylmethylpropylamine and the like as an aminating agent.

Generally, the amination involves combining the haloalkylated copolymer beads and at least a stoichiometric amount of the aminating agent (ie, a mixture of ammonia or amine) with the aromatic nucleus of the aminating monomer at reflux. Heating to a temperature sufficient to react with a halogen atom bonded to the carbon atom at the α-position. A swelling agent such as water, ethanol, methanol, methylene chloride, ethylene dichloride, dimethoxymethylene or a combination thereof is optionally and preferably used. Conventionally, amination is performed under conditions such that the anion exchange groups are uniformly dispersed throughout the beads. Such a complete amination takes about 25
It is achieved at a reaction temperature of from about 2 to about 24 hours at a reaction temperature of from about 150C to about 150C.

Methods for converting copolymer beads other than poly (vinyl aromatic) beads to anion exchange resins are described in Helfferich, pp. 48-58, supra. Further, methods of attaching other types of anion exchange groups, such as phosphonium, to the copolymer beads are described therein.

Cation exchange resin beads are prepared using techniques well known to those skilled in the art for converting cross-linked copolymers of mono- and polyethylene-based unsaturated monomers into cation exchange resins.
Methods for preparing cation exchange resins are described in U.S. Pat.
007, 2,500,149, 2,631,127, 2,664,801
No. 2,764,566 and F. Helfferich. In general, useful cation exchange resins are strong acid resins prepared herein by sulfonating copolymer beads. Although sulfonation can be performed directly, generally the beads are swelled using a suitable swelling agent and the swollen beads are reacted with a sulfonating agent such as sulfuric acid or chlorosulfuric acid or sulfur trioxide. Preferably, an excess amount of sulfonating agent is used, for example, about 2 to about 7 times the weight of the copolymer beads. The sulfonation is performed at a temperature from about 0 ° C to about 150 ° C.

Hereinafter, the present invention will be described in comparison with the related art. FIG. 1 shows an example of a scanning electron micrograph of various polymer adsorbents composed of various ion exchange resins. According to FIG. 1, (a) a conventional gel type general-purpose product (unused new product) It can be seen that the surface state is extremely smooth. (B) shows the result of observing what was used for a long period of time in a pure water production apparatus and then discarded as used. According to various research results of the present inventors, the removal efficiency of suspended substances (colloidal substances) of metal oxides contained in trace amounts in pure water with a polymer adsorbent is low when the adsorbent is new. It has been found that it tends to increase with aging. One of the causes is that with the aging of the polymer adsorbent, the adsorbent is likely to adsorb the colloidal substance and deteriorates, and the colloidal substance changes to a state where it is easily taken in through the surface of the adsorbent. Can be This phenomenon is generally described as a change in the adsorbent substrate due to irreversible swelling of the polymer adsorbent by oxidation. As a result, it can be seen that the smooth surface as shown in the photograph (a) is transformed into a turtle-like and / or scale-like form as shown in (b), and is also transformed into a groove-like form. Next, (c) shows the surface condition of a porous (porous) type general-purpose product (new unused product). Although the colloidal substance removal efficiency of this type of adsorbent shows high performance immediately after the start of use, the colloidal substance penetrates into the pores in a relatively short time, and the pores are closed, so that the removal efficiency drops rapidly. On the other hand, (d)
The surface condition of the new polymer adsorbent (unused new product) according to the present invention, which is clearly different from the conventional gel-type and porous-type unused new products, and is rather similar to the condition of (b). It has a state of having done. That is, it can be understood that the product of the present invention is a polymer adsorbent having a structure that exhibits excellent ability to adsorb and remove colloidal substances from an early stage.

FIG. 2 shows an example of the result of investigation on the removal efficiency of metal oxides contained in the water to be treated, using the degree of crosslinking of various polymer adsorbents as a parameter. In FIG. 2, the horizontal axis represents the degree of crosslinking of the adsorbent, and the vertical axis represents the concentration of the metal oxide (in this case, the concentration of iron oxide) that has passed through the treated water without being removed. According to the results of various studies by the inventors, the ability of the polymer adsorbent to remove metal oxides in pure water depends on the degree of cross-linking of the adsorbent. I found a phenomenon of improvement. Furthermore, as a result of the present invention, even with a polymer adsorbent having the same degree of cross-linking, a significant difference may occur in the ability to remove metal oxides due to differences in the surface state and / or structure such as the surface layer. found. FIG. 2 shows that the metal oxide removal ability of the product of the present invention is remarkably superior to that of a conventional gel-type general-purpose product.

Fig. 3 shows the effective specific surface area measured from a krypton gas adsorbent (measurement of specific surface area by BET method) as one of means to quantitatively grasp the surface state of polymer adsorbent.
Fig. 2 shows the results of an investigation of the relationship between the specific surface area and the metal oxide removal efficiency. It is normalized to 1 and the relative value is compared. As in FIG. 2, it can be seen from this figure that the product of the present invention has an excellent ability to remove metal oxides.

Since the amount of cross-linking agent, e.g., DVB, used in the preparation of the core / shell structured beads varies as a function of the structure radius depending on the technique used to prepare the beads,
A method representing cross-linking that reflects this fact is employed. For unfunctionalized copolymer beads, the toluene swell test is useful for determining the "effective" crosslink density as described in Example 2. For the resin with the functional group, "Apparent Relative Crosslink Percenta
It is reasonable to employ a moisture absorption test to determine what is referred to in Examples 2 and 4 as "ge".

This value is the water absorption capacity of the functionalized resin,
It is derived by comparing to a predetermined moisture absorption capacity of a standard gel-type resin having the same function and the same ability and made from the same copolymer.

In order to obtain a standard by which the `` Apparent Relative Crosslink '' can be determined in practical daily work, a series of standard gel forms, e.g., known DVB contents, e.g. 4,6,8,10,12
% Styrene-DVB resin is prepared. These resins are provided with the desired functional groups, and each level of DVB
Depending on the resin content, a graph of the amount of water absorbed at various capacities for each functional group, eg, 3.0, 3.5, 4.0, 4.5, 5.0 meq / g, is plotted from the experimental results.

The core / shell ion was then compared by comparing the measured water absorption capacity of the shell / core resin having the same function with the same level of ion exchange capacity, which was normally recorded in% by weight of water absorbed. It is possible to know the amount of the DVB cross-linking agent in the standard gel-type resin showing the same level of water absorption as the exchange resin. "Apparent Relative Crosslink Percen
"tage (apparent relative degree of cross-linking)" is reported as the weight percent of DVB cross-linking agent present in a comparable standard resin.

In the present invention, Component 1 and Component 2 resins comprise no more than 8%, preferably about 7% or less, more preferably about 6% or less, 3% or more, preferably about 4% or more, Most preferably, about 5% or more of "Appa
rent Relative Crosslink Percentages. "

There is no significant change in the operation required for the process of the present invention in a BWR plant, except that the ion exchanger currently used for ion removal purposes is replaced by the mixed bed ion exchanger described herein.

When "breakthrough" occurs, the mixed bed exchanger can be reactivated many times, usually by backwashing and stirring the bed. However, due to the low levels of radioactivity of the trapped iron ions and particles, the beds are not usually regenerated by exposure to strong acids or bases in the sense of being used as ion exchangers. Instead, the resin along with the captured radioactive material is typically consolidated, collected, and processed in the form of other low-level waste from nuclear power reactors.

When predetermined steps are taken to detect when breakthrough occurs and to re-activate the bed or collect and treat spent resin, the waste from the bed will have a low level scintillation detector and Monitored by standard means such as iron analysis techniques.

Due to the excellent strength and crush resistance of the resin, the generation of "microbes" from the resin is minimized, which further enhances the performance and life of the resin bed.

"Microorganisms" generated during shipping and handling of resin particles
A standardization operation of sieving the resin to remove ash is, of course, used during the initial charge to maximize the performance of the mixed bed ion exchanger.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Example 1 In order to confirm the effects of the present invention, a mixed bed column test was performed.

Mixed-bed column test 1) Test conditions A test was performed using the test apparatus shown in FIG. 4 under the following test conditions.

Specifications of polymer adsorbent (ion exchange resin): Degree of crosslinking (XL%) of general-purpose strong acidic gel type cation exchange resin (H type) 6
% And 8% and general-purpose strong basic anion exchange resin (OH
Combination of standard type of standard type), XL = 8% of general-purpose strong acidic gel type cation exchange resin and standard type of general-purpose strong basic gel type anion exchange resin, used in pure water production equipment for many years The cation exchange resin was estimated to be XL = 7% based on the measured moisture content at that time, and the XL of the general strong acid porous cation exchange resin = 8% and the combination of standard products of general-purpose strong basic porous type anion exchange resin, and XL of 6%, 8% and 10% of the new strongly acidic cation exchange resin of the present invention The resin was combined with a new strong basic anion exchange resin and tested in a mixed bed state.

Amount of resin used: A cation exchange resin / anion exchange resin volume ratio = 1.66 / 1.0, and a layer height equivalent to 90 cm (about 21) was mixed and packed into a column. Then, pure water in which a trace amount of iron oxide as a metal oxide was suspended (about 17.5 ppb as Fe) was passed.

Water flow velocity: LV = 108 m / hr Water flow period: 3 cycles of about 16 days per cycle 2) Test results Fig. 5 shows an example of test results. In FIG. 5, the horizontal axis indicates the number of days of water passage, and the vertical axis indicates the metal oxide concentration (iron oxide concentration: ppb as Fe) at the inlet and outlet of the column.

From the above results, when the degree of crosslinking of the cation exchange resin is compared using the same index, the product of the present invention shows that iron oxide, which is a suspended substance, is less than a general-purpose gel type product and its used product and a general-purpose porous ion exchange resin. The removal efficiency of iron oxides is better, and the lower the degree of cross-linking of the strongly acidic cation exchange resin, the better the removal efficiency of iron oxides. It was proved to show. According to the various research results of the present inventors, if the degree of crosslinking of the cation exchange resin is too small, the crushing strength of the resin base is reduced, and the total exchange capacity is also reduced. It has proven to be difficult to handle. The practical lower limit of the degree of crosslinking is 3%.

In addition, about this test result, a cation exchange resin is plotted on the horizontal axis.
That is, FIG. 2 shows the results obtained by taking the degree of crosslinking (XL%) of the polymer adsorbent, taking the concentration of metal oxide in the treated water on the vertical axis, and performing data processing.

In the following examples, all "parts" and "percents" are by weight unless otherwise indicated.

Example 2 In a 3 liter stainless steel reactor with stirrer, 0.3% with a particle size of 150-300 microns
35 parts by weight of the crosslinked styrene / divinylbenzene copolymer seed and a sufficient amount of water to suspend the seed particles. Further, with stirring, 1.9 parts of divinylbenzene (D
VB), 63 parts of styrene (based on the total amount of all monomers used) 0.036 parts of t-butyl peroctoate (TBP
O), consisting of (based on the total amount of all monomers used) 0.025 parts of t-butyl perbenzoate (TBPB), 0.15 parts of carboxymethylmethylcellulose (CMMC) and 0.15 parts of sodium dichromate Add initial monomer charge. After adding the monomer raw materials, water is added so that the weight ratio of the aqueous solution to the organic phase becomes 1.0. Add 7 reaction mixture
Heat to 0 ° C. and hold at 70 ° C. for 3 hours. In the meantime, 98.5% of styrene and 1.5% of DVB start to react. The monomer material is initially charged with 7
The monomer feed is added at a constant rate to the reactor over 10 hours until it consists of 1.4% by weight. The reaction mixture is heated to 90 ° C. for an additional 1.5 hours, and the temperature is increased and heated at 100 ° C. for about 1.5 hours.

A part of the copolymer beads thus obtained is dried, and 20 ml is measured using a column. Next, the beads are swollen in toluene and the volume change of the beads is measured. From the volume change, the effective crosslink density was determined by John Wiley and Sons in 1966.
Kirk-Othmer Dictionary of Chemistry and Technology, Vol. 2, No. 879
Determined using the graph depicted in the "Ion Exchange" section on page RMWheaton and AHSeamster.

100 g of the copolymer beads are chloromethylated by reacting with excess chloromethyl methyl ether in the presence of iron chloride. The chlormethylated beads are then reacted with trimethylamine to produce a strong base anion exchange resin with multiple quaternary ammonium ions. The anion exchange resin is tested for percent spherical, crush strength, resin size, osmotic shock resistance, capacity per dry resin weight and water retention capacity.

The crushing strength of the anion exchange resin in this and the following examples is determined by testing about 30 beads using a Chatillion scale, type DPP-1KG. The force required to crush the individual beads is recorded in grams for the crush strength obtained as an average of about 30 such tests.

The percentage value of the resin beads, which are unbroken spheres (ie, "percent complete spherical"), is measured by placing a small amount of resin in a Petri dish. A microscope with a camera
Set so that 200 resin beads are within the field of view of the camera. Take a photo. From the photograph, count the total number of beads, the number of crushed or broken beads, and calculate the percentage of spherical beads.

The size of the resin beads swollen with water is determined by screen analysis.

The osmotic shock resistance of the resin beads is tested by the method described above. Here, the beads were contacted alternately with 8M HCl and 8M NaOH for 10 cycles, and the result was the percentage of beads remaining uncrushed after 10 cycles of testing, using the counting method using micrographs described above. Obtained as a number.

The capacity per dry resin weight is determined by drying the chloride type resin sample under an infrared lamp to a degree of swelling that gives a constant weight. The dried resin is cooled to room temperature in a closed container. Weigh about 0.5 grams of dry resin and place in a suitable flask. The resin was then mixed with 100 ml of distilled water, 4 ml of sulfuric acid and 5 g of Na ₂ SO _{4 for} 70-8 for 5 minutes.
Heat at 0 ° C. The mixture is cooled and titrated with 0.1N AgNO ₃ using a chloride-sensitive electrode until an endpoint is indicated.
Volume per dry resin weight is given as resin meq / g. The prepared resin materials are as follows.

Original perfect spherical percentage: 98 Average crushing strength: 1470 g / bead Resin bead size: 600-1000 microns Percentage not destroyed (10 cycles of osmotic shock test): 80 Capacity per dry resin weight: 4.28 meq / g Toluene swelling effective Crosslink density: 4 DVB average percent: 1.64 (DVB percent used to prepare copolymer beads calculated based on the total amount of seeds and all monomer ingredients) Example 3 Method described in Example 2 A copolymer bead is prepared as follows.

In a sealed stainless steel reactor with a stirrer, 100 parts of water and a uniform average particle size of 350-360
Styrene-DVB (0.3% DVB) copolymer is included as a micron seed. The mixture is agitated mechanically. In a reactor, 87.1% styrene, 12.4% 56% DVB solution, 0.18
% Monomer mixture consisting of 12% TBPO and 0.14% TBPB
And the resulting mixture is stirred at 30 ° C. for 1 hour until the monomer mixture is completely absorbed by the seed particles.

In reactor, 97.8% water, 1.7% gelatin and 0.5%
Suspension consisting of (30% active) sodium lauryl sulfate
Add 127.8 parts and reduce the pressure in the reactor to avoid further explosion of the air / monomer mixture. Heat the material in the reactor to 78 ° C. and maintain the temperature for 2 hours.

96.4 parts styrene and 2 parts (3.6 parts 56% active solution) D
A second monomer feed comprising VB is pumped into the reactor at a rate of 1 part per minute for 4 hours until 240 parts of the second monomer feed have been added. The interior of the reactor was maintained at 78 ° C. for more than 3 hours, then
C. and maintained at that temperature for 2 hours to complete the polymerization of the monomer.

The interior of the reactor is cooled to below 40 ° C. and the beads formed are washed with water to remove the suspending agent and dried.

Example 3A In the method described in Example 2, a portion of the copolymer beads prepared by the method described in Example 3 is functionalized with chloromethyl methyl ether and trimethylamine by a standard method. , Is converted to a strong base anion resin. The resulting anion exchange resin beads are in the chloride form and have the following properties:

Average crushing strength: 460 g / bead Resin bead size (± 10%): 550 microns Percentage not broken (10 cycles of osmotic shock test): 95 Apparent Relative Swell Crosslink Percentage: 6 Capacity per dry resin weight: 3.9 meq / g Example 3B A portion of the copolymer beads prepared as described in Example 3 was converted to a strong acid cationic resin by standard means of sulfonation in a glass lined reactor in the following manner. Is done.

To the reactor is added 464 parts of 99% sulfuric acid, to which 100 parts of copolymer beads are gradually added with mechanical stirring. They are treated with a dilute sulfuric acid solution until the beads are fully hydrated. The resin beads are treated in a 2 molar sodium hydroxide solution, converted to the sodium form, and washed with water to remove salts and excess potassium.

In the sodium form, the resulting cation exchange resin beads have the following properties.

Average crushing strength: 680 g / bead Resin bead size (± 10%): 580 microns Percentage not broken (10 cycles of osmotic shock test): 98 Apparent Relative Swell Crosslink Percentage: 6 Capacity per dry resin weight: 4.8 meq / g Example 4 The resin beads of Example 3A are first converted chromatographically to the carbonated form with a sodium carbonate solution, then converted to the hydroxyl form with 1 mol or more of caustic soda and then repeatedly washed with water. This converts to about 93% of the hydroxyl form. The resin beads of Example 3B are converted to about 98% hydrogen (acid) form by treatment with one or more moles of sulfuric acid and then repeatedly washing in water to remove excess acid and salts. .

Each resin of the water-containing slurry was then combined in a suitably sized vessel at a ratio of 2 parts cation exchange resin (volume, wet) to 1 part anion exchange resin, then 2 parts. The two seeds are mechanically mixed by sparging with air to obtain a relatively evenly distributed bed. This homogeneous mixture is then carefully placed in a vertical column with sufficient diameter to handle the condensate flow in the BWR. When a suitable valve is operated, the condensate flows into the fixedly installed column. The condensate to the column has about 20 parts per billion (20 ppb) of iron. In such a two column flow, the effluent from the column contains between 1.0 ppb and 1.5 ppb of iron per day of operation and drops from 0.5 ppb to 0.6 ppb in 2 days of operation and 15 days of operation Contained 0.3 to 0.9 ppb of iron.

Example 5 In a manner similar to Example 4, a mixed bed was prepared from a commercially available gel anion and cation exchange resin having the following characteristics.

Anion exchange resin Average crushing strength: 390 g / bead Bead size range: 300-1200 microns Percent unbreakable (10 cycles of osmotic shock test): 45 Apparent Relative Crosslink Percentage: 8 Capacity per dry resin weight: 3.9 meq / g Cation exchange resin Average crushing strength: 680 g / bead bead size range: 300-1200 microns Percent not broken (10 cycles of osmotic shock test): 45 Apparent Relative Crosslink Percentage: 8 Capacity per dry resin weight: 4.8meq / g A mixed bed of these two anionic and cationic resins, in substantially the same proportions as the resin of Example 4, was loaded onto a column and the same condensate stream (20 ppb Iron). The initial effluent from the mixed bed was about 0.5 ppb of iron per day of operation, about 0.5 ppb of iron per day of operation,
Then it rose steadily, after which it reached about 5 ppb of iron on the 5th run and contained 4.5 ppb of iron on the 15th run.

〔The invention's effect〕

According to the present invention, in a mixed-bed filtration and desalination apparatus using a polymer adsorbent made of an ion-exchange resin, when removing trace amounts of suspending impurities present in pure water, metal oxide which is a main component thereof is removed. Substances (especially iron oxides) can be sufficiently removed. As a result, for example,
In particular, it will be possible to dramatically remove and remove trace amounts of iron oxides in the condensate (primary cooling water) of boiling water nuclear power plants, contributing to the effect of reducing the radiation dose to workers during periodic inspections. Becomes possible. In the semiconductor manufacturing industry, the ability to effectively adsorb and remove similar suspended impurities present in a very small amount in ultrapure water greatly contributes to improving the yield of semiconductor products.

[Brief description of the drawings]

FIG. 1 is a particle structure photograph showing the surface state of various polymer adsorbents by a scanning electron microscope, and FIG. 2 shows the relationship between the degree of crosslinking of various polymer adsorbents and the concentration of metal oxides in the treated water. FIG. 3 is a graph showing a relative comparison between the specific surface area of the polymer adsorbent and the removal efficiency of the metal oxide, and FIG. 4 is a mixed bed conducted to prove the results of the present invention. FIG. 5 is a system diagram of a column type column test apparatus, and FIG. 5 is a graph showing an example of a breakthrough curve relating to metal oxide removal by various ion exchange resins among mixed bed type column test results. 1 ... concentration of metal oxide in the inlet water, 2 ... outlet of gel type general-purpose product (degree of crosslinking 8%), 3 ... outlet of the present invention product (degree of crosslinking 10%), 4 ... outlet of porous type general-purpose product (degree of crosslinking) 5 …… 2 Used waste outlet (corresponding to 7% cross-linking degree), 6… Gel type general-purpose outlet (cross-linking degree 6%), 7… The present invention outlet (cross-linking degree 8%) 8: Outlet of the product of the present invention (crosslinking degree: 6%).

──────────────────────────────────────────────────続 き Continued on the front page (72) Masahiro Hagiwara, Inventor 11-1 Haneda Asahicho, Ota-ku, Tokyo Inside Ebara Works Co., Ltd. (72) Inventor Takeshi Izumi 11-1, Haneda Asahi-cho, Ota-ku, Tokyo Stock (72) Inventor Marking Way 1-5-13 Hiroo, Shibuya-ku, Tokyo (56) References JP-A 1-159051 (JP, A) JP-A 1-156303 (JP, A) JP-A-63-79066 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 20/22-20/26

Claims (21)

(57) [Claims] 1. A granular or powdery cation exchange resin and / or a negative ion for adsorbing and removing suspending impurities present in water to be treated in an ultrapure water production apparatus for semiconductor industry or a condensate purification apparatus of a steam power plant. When an organic polymer adsorbent containing an ion-exchange resin is inspected with a scanning electron microscope in a field of view of 500,000 to 200,000, it can be confirmed that the surface of the adsorbent has a granular binding structure. Adsorbent for removing turbid impurities. 2. The adsorbent according to claim 1, wherein the granular bonding structure is observed by a scanning electron micrograph, and the apparent unit particle size of the measured granular fine particles is 0.1 to 1.0 μm. A spherical adsorbent in which the granules exhibit a collective binding as a result, and the adsorbent has a diameter of 0.2 to 1.2 mm. 3. The adsorbent according to claim 2, wherein the adsorbent has grooves on its surface, and the grooves have a turtle-like and / or scaly pattern. 4. The adsorbent according to claim 3, wherein said turtle-shaped or scale-shaped constituent unit has a unit area of 1 to 50 μm ² , and each constituent unit has a width of 0.1 to 5 μm and a depth of 0.1 to 5 μm. Adsorbents adjoining via said grooves of 0.1-5 μm. 5. The adsorbent according to claim 3, wherein said groove has a length per unit area of 100 to 1000 mm / mm ^2.
Is an adsorbent. 6. The adsorbent according to claim 2, wherein the effective specific surface area measured from the amount of krypton adsorbed is 0.02 to 1.00 m ² / g based on the dry weight of the adsorbent. 7. A powdery adsorbent produced by pulverizing the adsorbent according to claim 2. 8. The adsorbent according to claim 1, wherein at least the cationic resin contains gel-type copolymer beads having a core / shell structure before imparting a functional group. 9. A method for removing suspended impurities, comprising forming a packed layer or a filtration layer using the adsorbent according to any one of claims 1 to 7. 10. The adsorbent according to claim 1, wherein said cation exchange resin comprises gel-type copolymer beads having a core / shell structure, and is produced by a method comprising the following steps: Forming a plurality of polymer matrices containing free radicals in a continuous phase; (b) absorbing a monomeric material comprising at least one monomer into said matrix without adding a free radical initiator And the monomer material absorbed in the matrix is
A step in which free radicals in the matrix act as a polymerization catalyst in the matrix of the monomer raw material and are subjected to radical polymerization conditions; and (c) a step of providing a functional group to the obtained copolymer beads. 11. The adsorbent according to claim 1, wherein said anion exchange resin comprises gel-type copolymer beads having a core / shell structure, and is produced by a method comprising the following steps: Forming a plurality of polymer matrices containing free radicals in a continuous phase; (b) absorbing a monomeric material comprising at least one monomer into said matrix without adding a free radical initiator And the monomer material absorbed in the matrix is
A step in which free radicals in the matrix act as a polymerization catalyst in the matrix of the monomer raw material and are subjected to radical polymerization conditions; and (c) a step of providing a functional group to the obtained copolymer beads. 12. The adsorbent according to claim 1, wherein:
An adsorbent comprising the cation exchange resin according to claim 10 and the anion exchange resin according to claim 11. 13. The adsorbent according to claim 10, wherein
An adsorbent, wherein the copolymer comprises a copolymer prepared from a styrene monomer and divinylbenzene. 14. The adsorbent of claim 12, wherein said cation exchange resin has a crush strength of at least 500 g / beads and said anion exchange resin has a crush strength of at least 400 g / beads. 15. The adsorbent according to claim 12, wherein said cation exchange resin and said anion exchange resin are brought into contact with 8 mol of hydrochloric acid and 8 mol of sodium hydroxide alternately 10 times. Adsorbent that has osmotic pressure resistance so that less than 15% of it is destroyed. 16. The adsorbent according to claim 12, wherein the cation exchange resin and the anion exchange resin have a volume ratio (cation exchange resin: anion exchange resin) of 2: 1 to 1: 2. Adsorbent mixed in. 17. A method for adsorbing and removing suspended impurities present in water to be treated in an ultrapure water producing apparatus for semiconductor industry or a condensate purifying apparatus for a steam power plant, the method comprising the step of: A method for removing suspended impurities, comprising removing suspended impurities by contacting the adsorbent for removing suspended impurities. 18. The method according to claim 17, wherein the cation exchange resin is the resin according to claim 10. 19. The method according to claim 17, wherein the anion exchange resin is the resin according to claim 11. 20. The method according to claim 17, wherein the adsorbent is a cation exchange resin according to claim 10 and an anion exchange resin according to claim 11. 21. The method according to claim 20, wherein said cation exchange resin and said anion exchange resin have a degree of crosslinking of 4 to 8%.