JP2010158640A - Magnetoseinsitive chelating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide magnetosensitive chelating material which simply, safely, and efficiently traps, removes, concentrates, and recovers metal ions from industrial wastewater, river water, and groundwater by employing a magnetic separation technique; which has good magnetosensitivity due to a high magnetic substance content; and which is produced by a safe method. <P>SOLUTION: The magnetosensitive chelating material to be used is a material having polymer side chains in which chelating groups are arranged on the coating surface of microcapsules encapsulating magnetic particles of which the coating is formed by an in situ polymerization method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetosensitive chelate material that can be easily controlled for dispersion and aggregation by the action of an external magnetic field and can be used as a separation functional material for recovering a trace amount of metal ions contained in water or an organic solvent. Is.

  Industrial wastewater may contain various harmful metal ions, and from the viewpoint of preventing environmental pollution, these need to be sufficiently removed by wastewater treatment. In addition, some of the various components contained in river water and groundwater have adverse effects on the human body, and sufficient consideration must be given when using river water and groundwater. On the other hand, useful metal ions to be recovered may be contained in industrial wastewater, and it is also necessary to recover these efficiently from the viewpoint of effective utilization of resources.

  The most commonly used method for removing harmful metal ions is a method of precipitating harmful metal ions with a polymer flocculant and a chelating agent. The generated sediment is separated from the waste water and mainly landfilled, but it causes new problems such as securing a landfill site and leakage from the landfill site. On the other hand, if it is attempted to recover useful metal ions by this precipitation method, it is necessary to separate the useful metal ions and the agent for forming the precipitate after the separation of the precipitate. For this operation, a strong acid or a strong base is required, and a new waste derived from a drug for forming a precipitate is generated, which is not preferable in terms of cost and environment. Although treatment with a filter into which a chelate group for collecting metal ions has been proposed, there is a problem that the flow rate is likely to decrease in a relatively short time, and the performance is difficult to recover by backwashing.

  As another method, ion exchange resins and chelate resins have been proposed and widely used. Since all of these resins are in the form of beads having a diameter of about 0.5 mm, they are used in a packed tower system, and facilities for pressurized water supply are required. As the processing amount increases, the flow rate frequently decreases, such as clogging, and it is necessary to perform backwashing each time. The adsorption performance depends on the resin filling amount and the water flow rate, and if the flow rate is reduced to increase the adsorption performance, the amount of the treatment liquid decreases, and if the resin filling amount is increased, there is a dilemma. There is also a problem that the diffusion rate of ions into the resin particles is small. This is because these resins have a rigid three-dimensional structure due to a crosslinking agent such as divinylbenzene. Since the diffusion rate is slow, not only does it take a long time to regenerate the resin, but a large amount of reclaimed wastewater is generated.

  As materials that can replace ion exchange resins and chelate resins, fiber-based ion exchangers and chelate exchangers have been proposed and commercialized (for example, see Patent Document 1). These have advantages that the specific surface area of the fiber is large and that the ion exchange group or chelate group is introduced on the fiber surface, so that the adsorption rate is higher than that of the ion exchange resin or chelate resin. However, even in the case of ion exchangers and chelate exchangers based on fibers, the use form by the packed tower system is the mainstream for commercialization, and equipment for water supply is required (for example, see Patent Document 2). ). Compared to ion exchange resins and chelate resins, these materials have a problem that they are easy to form a compacted state downstream in the flow direction when charged into the packed tower or discharged to the outside, and have poor transportability. Yes.

  As a method for solving these problems, a proposal has been made to use a magnetic separation technique together (for example, see Patent Document 3). Magnetic particles having an organic compound layer having a chelate group are added to the water to be treated, and after the chelate is formed, the magnetic particles are magnetically separated. In combination with a superconducting magnetic separator that has been improved in recent years, it is said that magnetic particles and water to be treated can be efficiently separated. However, the proposed magnetic particles form a chelate group using a functional group bonded to the main chain of the polymer layer covering the particle, and there is a problem that the density of the chelate group is low. On the other hand, the proposal which raises the abundance density of a chelate group by introducing the side chain which has a chelate group by graft reaction is made (for example, refer patent documents 4 and 5 and nonpatent literature 1). According to the study of the present inventors, in these proposals, radiation such as γ-rays, β-rays, X-rays, etc., which are undesirable from the viewpoint of safety in order to carry out the graft reaction, or unstable acid halogens are required. There is a problem that a chemical is necessary. Alternatively, in order to secure the starting point of the graft reaction, suspension polymerization using a high concentration dispersant and a special reaction apparatus is required, and the polymer layer covering the particles has low mechanical strength, so the thickness is increased. As a result, the content ratio of the magnetic substance contained in the magnetic particles is decreased and the magnetic sensitivity is lowered, so that the practicality is poor.

JP 2000-248467 A JP 2006-26462 A JP 2003-275758 A International Publication No. 2005/042622 Pamphlet JP 2006-265451 A

Z. Y. Ma, et al., “Synthesis of Magnetic chelator for High-Capacity Immobilized Metal Affinity Adoption of Protein by Criteria Gram Pol. 6987-6994

  The present invention has been made paying attention to the circumstances as described above, and the problem is that from industrial wastewater, river water, groundwater, using magnetic separation technology, simply, safely and efficiently, Providing a magnetosensitive chelate material that can collect, remove, concentrate, and recover metal ions, and has a good magnetic sensitivity due to its high magnetic substance content ratio, and can be produced by a safe method There is to do.

  The present inventor has intensively studied the above problems, and in a magnetically sensitive chelate material comprising microcapsules encapsulating magnetic particles, the microcapsule film is produced by an in situ polymerization method, and the polymer surface has a polymer side chain having a chelate group. It is preferable that the magnetosensitive chelate material characterized by having an extremely effective solution to the problem described above, and that the chelate group is a group derived from iminodiacetic acid or a group derived from N-methylglucamine. As a result, the present invention has been reached.

  In the magnetically sensitive chelate material of the present invention, a chelate group having a chelating ability to a metal ion is arranged in a polymer side chain extending from the surface of a microcapsule film enclosing magnetic particles, and the chelate group per unit volume of microcapsule The existence density is high. Therefore, metal ions can be efficiently collected, removed, concentrated and recovered by adding a small amount to the water to be treated. The microcapsule film formed by the in situ polymerization method is thermally and chemically stable and can be thinned. As a result, a magnetically sensitive chelate material having a high magnetic substance content ratio can be obtained. In addition, both the production of the microcapsules and the introduction of the polymer side chain can be carried out by a safe method without using special chemicals, equipment, electromagnetic waves or the like.

  In the magnetically sensitive chelate material of the present invention, a magnetic particle-encapsulating microcapsule in which a film is produced by an in situ polymerization method has a polymer side chain having a chelate group on the film surface.

  The magnetic particles used in the present invention are preferably formed from at least one magnetic material selected from the group consisting of metals and oxides thereof, alloys and oxides thereof. Examples of the metal include iron, cobalt, and nickel. Since it is excellent in chemical stability, at least one or more kinds of magnetic particles selected from the group consisting of maghemite, magnetite, nickel zinc ferrite, and manganese zinc ferrite are preferable. Magnetite having excellent sensitivity to a magnetic field is particularly preferable. The size of the magnetic particle is not particularly limited as long as it is a size encapsulated in the microcapsule, but the longest axis length of the magnetic particle is preferably 4 nm to 10 μm.

  The shape of the magnetic particles used in the present invention is not particularly limited, and may be spherical, elliptical spherical, plate-like, needle-like, or polyhedral such as a cubic shape, but is included in a microcapsule. It is preferably spherical or elliptical.

  Regarding the microencapsulation by the in situ polymerization method used in the present invention, for example, by Kondo Yasu et al., “New edition microcapsules—manufacturing method / property / application”, Sankyo Publishing Co., Ltd., 1987, Yasu Kondo et al. Capsule, its functions and applications, "Japanese Standards Association, 1991, etc.

  In microencapsulation by the in situ polymerization method, a monomer or a prepolymer and a catalyst are dissolved in either one of an inner phase (core material) and an outer phase that do not mix with each other, and a film is formed at the interface. Monomers or prepolymers used for film formation include acrylic esters, methacrylic esters, vinyl acetate, combinations of styrene and divinylbenzene, combinations of organic amines and water-soluble epoxy compounds, combinations of heterocyclic amines and polyhydric aldehydes, etc. Various types are known, but in particular, microcapsules having a urea-formaldehyde polymer film by polycondensation of urea and formaldehyde or a melamine-formaldehyde polymer film by polycondensation of melamine and formaldehyde give a high-concentration capsule. It has advantages such as excellent water resistance and solvent resistance, and excellent denseness, and is preferably used in the present invention.

  The diameter of the microcapsule used in the present invention is preferably 1 to 100 μm. When the diameter is smaller than 1 μm, the number of magnetic particles contained is reduced, and the magnetic sensitivity may be reduced. When the diameter is larger than 100 μm, the mechanical strength may decrease. In addition, the diameter of a microcapsule is calculated | required based on the electron micrograph.

  Specific examples of chelate groups used in the present invention include groups derived from iminodiacetic acid, iminodiphosphonomethane, nitrilotriacetic acid, ethylenediaminetetraacetic acid, 1,3-propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, iminodiethanol and the like. Can be mentioned. In addition, various polyvalent amines such as ethylenediamine, 1,3-diaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine and the like, various amino acids such as phenylalanine, lysine, leucine and valine And groups derived from proline and the like, groups derived from various sugars such as glucamine and N-methylglucamine, and groups derived from 8-hydroxyquinoline. Among these, a group derived from iminodiacetic acid having high selectivity with respect to heavy metals such as cobalt, nickel and copper, and N- with high selectivity with respect to semimetals such as boron, arsenic, germanium and selenium. Groups derived from methylglucamine are preferred.

  The chelate group used in the present invention is introduced into a polymer side chain bonded to the surface of the microcapsule film. In order to realize such a structure, 1) a method in which a monomer having a chelate group is graft-polymerized on the surface of the microcapsule film, and 2) a monomer having a functional group that can be used for introducing a chelate group in the latter stage is grafted. There is a method of introducing a chelate group after polymerization. Examples of the monomer having a chelate group used in 1) include a reaction product of glycidyl methacrylate and iminodiacetic acid, iminodiethanol or N-methylglucamine. However, since the monomer having a chelate group generally has a high molecular weight, the reactivity tends to decrease and the graft ratio may decrease, so the method 2) is preferred. Examples of the monomer having a functional group that can be used to introduce a chelate group in the latter stage used in 2) include glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether.

  As a polymerization initiation method for graft polymerization of the monomer onto the microcapsule surface, a method using radiation or a method using a sensitizer and ultraviolet rays can be used, but a special apparatus is not required and safety is high. A method using a redox initiator is preferable because the grafting reaction can be started at a low temperature. Specific examples of the redox initiator include a combination of a low-valent iron ion or copper ion and hydrogen peroxide or persulfate, or a tetravalent cerium salt.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples. The number of parts and percentages in the examples are based on mass unless otherwise specified.

<Manufacture of microcapsule 1 by in situ polymerization method>
To a mixture of 4 g of polyalphaolefin previously kneaded in a ball mill and 16 g of iron trioxide magnetic powder (manufactured by Toda Kogyo Co., Ltd., trade name: MAT-305), adjust the pH to 4.5 with acetic acid. 100 g of an α-methylstyrene-maleic anhydride copolymer aqueous solution adjusted to 5% by mass was added and stirred and mixed with a homomixer for 1 minute. Here, 6.5 g of 37% formaldehyde aqueous solution and 10 g of water were added to 5 g of melamine powder, the pH was adjusted to 8, and the melamine-formalin initial condensate aqueous solution prepared by heating up to a liquid temperature of 70 ° C. After stirring at 70 ° C. for 2 hours, the pH was adjusted to 9 to obtain a slurry of magnetic particle-containing microcapsules 1. The magnetic powder used for the preparation was almost entirely contained in the microcapsules. Therefore, the magnetic substance content of the microcapsule can be calculated as 58% in terms of solid content excluding the α-methylstyrene-maleic anhydride copolymer, and is easily aggregated using a permanent magnet having a magnet strength of 0.45T. I was able to. According to the observation with a scanning electron microscope, the particles had a spherical or elliptical spherical structure with a diameter of 20 to 80 μm.

<Manufacture of microcapsule 2 by in situ polymerization method>
Instead of 20 g of the polyalphaolefin-iron tetroxide magnetic powder kneaded product, 20 g of magnetic fluid (manufactured by Sigma High Chemical Co., Ltd., trade name: E-600; magnetic component 80%) is used. By operating in the same manner as in production, a slurry of magnetic particle-containing microcapsules 2 was obtained. Almost all of the magnetic material used for preparation was encapsulated in microcapsules. Therefore, the magnetic substance content of the capsule can be calculated as 58% in terms of solid content excluding the α-methylstyrene-maleic anhydride copolymer, and can be easily aggregated using a permanent magnet having a magnet strength of 0.45T. I was able to. According to observation with a scanning electron microscope, the particles had a spherical or elliptical spherical structure with a diameter of about 5 to 10 μm.

Example 1
5 g of slurry of microcapsule 1 was diluted with 40 ml of distilled water, 1.2 g of glycidyl methacrylate and 0.1 g of sodium dodecylbenzenesulfonate were added, and the mixture was stirred under a nitrogen atmosphere. A solution prepared by dissolving 0.24 g of diammonium cerium nitrate (IV) in 20 ml of 0.1 N nitric acid was added dropwise thereto at room temperature, and the mixture was further stirred for 2 hours. To this reaction product, 3.9 g of N-methylglucamine was further added and refluxed for 3.5 hours. After cooling, 70 ml of distilled water was added and stirred for 15 minutes, and then the supernatant was removed by decantation while drawing the solid content with a permanent magnet. The same operation was repeated twice using 200 ml of distilled water, and finally the solid was filtered to obtain a magnetosensitive chelate material. The yield was 1.6g.

Example 2
In the same manner as in Example 1 except that 2.1 g of iminodiethanol was used instead of 3.9 g of N-methylglucamine, 1.4 g of a magnetosensitive chelate material was obtained.

Example 3
Instead of 3.9 g of N-methylglucamine, the same operation as in Example 1 was performed except that 3.54 g of sodium iminodiacetate was used, to obtain 1.4 g of a magnetosensitive chelate material.

Example 4
A magnetosensitive chelate material (1.4 g) was obtained in the same manner as in Example 1 except that 4.1 g of sodium iminodipropionate was used instead of 3.9 g of N-methylglucamine.

Example 5
1.6 g of a magnetosensitive chelate material was obtained in the same manner as in Example 1 except that 5 g of the microcapsule 2 slurry was used instead of 5 g of the microcapsule 1 slurry.

(Comparative Example 1)
Langmuir, 2005, Vol. 21, p. The following operation was performed in accordance with the contents described in 6989 (Non-patent Document 1). First, a solution prepared by dissolving 11.8 g of ferric chloride hexahydrate and 4.3 g of ferrous chloride tetrahydrate in 400 ml of distilled water was maintained at 90 ° C., and 25% aqueous ammonia and then 10 ml of oleic acid were added. The mixture was further heated and stirred at the same temperature for 1 hour. After cooling, the supernatant was removed by decantation while drawing the solid content with a permanent magnet having a magnet strength of 0.45T. The same washing operation was repeated twice using 250 ml of distilled water. 47.5 ml of vinyl acetate, 2.5 ml of divinylbenzene, and 2.0 g of benzoyl peroxide were added to the residue, and 12.5 g of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA217) and 15 g of sodium chloride were distilled from this residue. The solution was dissolved in 400 ml of water overnight and placed under a nitrogen atmosphere. While stirring this mixture at the maximum output of the mechanical stirrer (450 rpm), the internal temperature was raised from room temperature to 60 ° C. over 1 hour, and the mixture was heated and stirred at the same temperature for 2 hours and further at 70 ° C. for 2 hours. The product could not be attracted and collected with a permanent magnet having a magnet strength of 0.45 T, and only a part of the product settled down even after centrifugation (4,000 rotations / minute × 20 minutes). For this reason, the subsequent chelating group introduction operation was abandoned. Whether or not the iron component was encapsulated in the microcapsules in this experiment was not clear by visual observation, but the magnetic substance content of the microcapsules was 8% even if all of the iron components were encapsulated.

(Comparative Example 2)
A chelate fiber (manufactured by Kirest Co., Ltd., trade name: Kirest Fiber GRY-L) was used as the chelate material of Comparative Example 2. This chelate fiber has a group derived from N-methylglucamine as a chelate group for boron ions.

(Comparative Example 3)
A chelate resin (manufactured by Mitsubishi Chemical Corporation, trade name: Diaion CR11) was used as the chelate material of Comparative Example 3. This chelate resin has a group derived from iminodiacetic acid as a chelate group for copper ions.

<Boron ion adsorption capacity>
0.2 g of the magnetosensitive chelate material obtained in Example 1 was added to 50 ml of a 9.1 mmol / liter boric acid aqueous solution, stirred at 20 ° C. for 3.5 hours, and then a permanent magnet having a magnet strength of 0.45 T was used. The solid content and the mother liquor were separated, and boron remaining in the mother liquor was quantified by inductively coupled plasma (ICP) emission spectroscopy. As a result, it was found that the boron ion adsorption capacity per 1 g of the magnetic chelate material was 1.3 mmol. It was also confirmed that the magnetically sensitive chelate material that adsorbed boron ions released the adsorbed boron ions with a 1 N hydrochloric acid solution and could be used again for the adsorption of boron ions.

  Similarly, the boron ion adsorption capacity per gram of the magnetically sensitive chelate material obtained in Examples 2 and 5 was determined to be 0.6 mmol and 1.3 mmol, respectively. It was also confirmed that the magnetically sensitive chelate material that adsorbed boron ions released the adsorbed boron ions with a 1 N hydrochloric acid solution and could be used again for the adsorption of boron ions.

  Boron ion adsorption ability was measured using 0.2 g of the chelate material of Comparative Example 2. However, the solid content and the mother liquor were separated by filtration using filter paper. It was found that the boron ion adsorption capacity per 1 g of this chelate material was 0.9 mmol.

<Copper ion adsorption capacity>
0.2 g of the magnetosensitive chelate material obtained in Example 3 was added to 50 ml of an aqueous 9.1 mmol / liter cupric sulfate solution, stirred at 20 ° C. for 3.5 hours, and then a permanent magnet having a magnet strength of 0.45 T. Was used to separate solids and mother liquor, and the copper ions remaining in the mother liquor were quantified by inductively coupled plasma (ICP) emission spectroscopy. As a result, it was found that the copper ion adsorption capacity per 1 g of the magnetic chelate material was 0.8 mmol. Similarly, the copper ion adsorption capacity per gram of the magnetosensitive chelate material obtained in Example 4 was determined to be 0.2 mmol.

(Comparative Example 3)
Copper ion adsorption ability was measured using 0.2 g of the chelate material of Comparative Example 3. However, the solid content and the mother liquor were separated by filtration using filter paper. It was found that the copper ion adsorption capacity per 1 g of this chelate material was 0.6 mmol.

  From the results of Examples 1 to 5 and Comparative Example 1, the magnetosensitive chelate material of the present invention can be produced by a safe method without requiring an unstable acid halide or the like. Moreover, it turns out that it can isolate | separate easily with a permanent magnet from the comparison with Examples 1-5 and Comparative Examples 1-3, and refinement | purification is also easy. In addition, Examples 1 and 5 and Comparative Example 2 have a group derived from N-methylglucamine as a chelating group for boron ion, and Example 3 and Comparative Example 3 have a chelating group for copper ion. Although it has a group derived from iminodiacetic acid, it can be seen that in any combination, the example of the present invention shows higher adsorption ability for the metal ion than the comparative example.

  Comparing the magnetically sensitive chelate materials of Examples 1 and 2, it can be seen that a group derived from N-methylglucamine as a chelate group is preferable because it exhibits a high adsorbing ability for boron ions, which are a representative metalloid species. . Further, when Examples 3 and 4 are compared, it can be seen that a group derived from iminodiacetic acid as a chelate group is preferable because it exhibits a high adsorbing ability for copper ions, which are representative species of heavy metals.

Claims (2)

  A magnetosensitive chelate material comprising microcapsules encapsulating magnetic particles, wherein the microcapsule film is produced by an in situ polymerization method, and the film surface has a polymer side chain having a chelate group.   The magnetosensitive chelate material according to claim 1, wherein the chelate group is a group derived from iminodiacetic acid or a group derived from N-methylglucamine.