JP2008214551A - Collecting agent for high valent metal ion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collecting agent (chelate resin) capable of efficiently and selectively collecting high valent metal ions having ≥3 valency included in a medium under an acidic condition. <P>SOLUTION: The high valent metal ions included in a medium can be easily collected under an acidic condition, by using a support comprising a compound having a hydroxam group as the collecting agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a collecting agent for collecting high-valent metal ions. More specifically, the present invention relates to a collecting agent that introduces a hydroxamic acid group into a carrier and can easily collect high-valent metal ions such as vanadium, iron, and titanium even under strong acidity.

  Ion exchange resins are widely used to remove metal ions such as calcium, magnesium, manganese, iron, copper, and zinc contained in rivers and wastewater, or to capture beneficial metal ions. Select low-concentration metal ions. The effect of adsorption is not necessarily satisfactory.

  On the other hand, chelate resins that have the property of selectively capturing chelates with heavy metal ions to remove and capture heavy metal ions such as copper, zinc, nickel, cobalt, and vanadium in the water treatment field Has been used. The structure is such that iminodiacetic acid, ethylenediaminediacetic acid, ethylenediaminetriacetic acid, thioglycolic acid, thiomalic acid, phosphoric acid, etc. are introduced into a rigid three-dimensional carrier formed by a crosslinking agent such as divinylbenzene. It is common.

  However, the above ion exchange resin and chelate resin are those that efficiently adsorb target metal ions when the sample solution containing the metal ions to be adsorbed is weakly acidic to neutral, and have an acidic pH of 6 or less. In particular, it was difficult to efficiently and selectively adsorb high-valent metal ions having a valence of 3 or more, particularly under strong acidity at pH 2 or higher.

In addition, most of the conventional chelate resins are bead-like resins having a rigid three-dimensional structure formed by a cross-linking agent such as divinylbenzene as described above. The diffusion rate of metal ions and regenerants is slow and there is a problem in processing efficiency.
JP 2000-73043 A JP-A-9-127092 JP-A-8-295966

  An object of the present invention is to provide a collecting agent capable of efficiently and selectively collecting high-valent metal ions having a valence of 3 or more contained in a medium under acidic conditions.

  The present inventors have found that by using a carrier into which a compound having a hydroxamic acid group is introduced as a scavenger, it is possible to easily collect high-valent metal ions contained in a medium under acidic conditions. I did it.

  That is, the present invention is characterized by the following items (1) to (5).

  (1) A metal ion scavenger having a valence of 3 or more, wherein a compound having a hydroxamic acid group is introduced into a carrier.

  (2) The collecting agent according to (1), wherein the carrier is polymer particles.

  (3) The collection agent according to (1) or (2), wherein the pH of the solution containing the metal ions to be collected is 6 or less.

  (4) The collection agent according to (1) or (2), wherein the pH of the solution containing the metal ions to be collected is 2 or less.

  (5) The collection agent according to any one of (1) to (4), wherein the compound having a hydroxamic acid group is desferrioxamine B (DFB).

  According to the present invention, it is possible to provide a collecting agent capable of efficiently and selectively collecting high-valent metal ions having a valence of 3 or more contained in a medium under acidic conditions, particularly under strong acidic conditions of pH 2 or lower. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail.

  The scavenger of the present invention is characterized in that it is obtained by introducing a compound having a hydroxamic acid group into a carrier, and in particular, titanium (IV), vanadium (V), iron (III), molybdenum (VI ), Niobium (V), tantalum (V), zirconium (IV) and other high valence metal ions having a valence of 3 or more can be efficiently and selectively collected even under acidic conditions. .

The hydroxamic acid group captures a high-valent metal ion with a siderophore structure, and therefore forms a stable wrap-around complex even under strong acidity at pH 2 or lower, and can collect the high-valent metal ion. Examples of the compound having a hydroxamic acid group include acetohydroxamic acid, salicylhydroxamic acid, benzohydroxamic acid, aminobenzodihydroxamic acid, desferrioxamine B (DFB), and the like. Among them, it is preferable to use DFB having three or more hydroxamic acid groups in one molecule in order to facilitate the formation of a siderophore structure, and in order to facilitate introduction into a carrier, it has H ₃ N ⁺ at the end. More preferably, DFB is used. A preferred DFB structure having H ₃ N ⁺ at the end is shown below.

  The carrier may be made of, for example, a vinyl polymer such as polyvinyl alcohol or styrene-divinylbenzene copolymer, an acrylic polymer such as polyacrylate or polymethacrylate, or a polymer that does not dissolve in the sample solvent. There is no particular limitation. The carrier is preferably polymer particles (beads), more preferably polymer particles having an average particle diameter of about 1 μm to 2 mm from the viewpoint of ease of synthesis, and particularly preferably, the classification is easy. From the viewpoint, the polymer particles have an average particle diameter of about 5 μm to 800 μm. In addition, although the said polymer particle can be manufactured by well-known polymerization methods, such as suspension polymerization method, dispersion polymerization, and soap free polymerization, it is preferable to manufacture by aqueous suspension polymerization at the point of the ease of superposition | polymerization.

  The polymer particles preferably have a functional group such as a hydroxyl group, an epoxy group, or a halogen group such as chloro or bromo to facilitate introduction of a compound having a hydroxamic acid group. It is more preferable that it has an epoxy group for ease.

  The polymer particles can be prepared, for example, by a copolymerization reaction of a polymerizable carbon-carbon double bond of a non-crosslinkable polymerizable monomer and a crosslinkable polymerizable monomer, and preferably an epoxy Copolymerization is performed using a non-crosslinkable polymerizable monomer or a crosslinkable polymerizable monomer having a functional group such as a group, a hydroxyl group, or a halogen group. Thereby, polymer particles having a functional group can be easily obtained. Of course, the functional group may be introduced by reacting epichlorohydrin or the like after the preparation of the polymer particles. Moreover, when introduce | transducing an epoxy group, it is preferable to use the non-crosslinkable polymerizable monomer which has an epoxy group.

  Examples of the non-crosslinkable polymerizable monomer having an epoxy group include acrylic acid and methacrylic acid derivatives having an epoxy group, styrene derivatives having an epoxy group, and more specifically, acrylic acid. Examples thereof include glycidyl, glycidyl methacrylate, glycidyl clonate, glycidyl itaconate, glycidyl fumarate, glycidyl malate, and vinylbenzyl glycidyl ester.

  The crosslinkable polymerizable monomer may be any monomer as long as it has two or more polymerizable groups in one molecule. The monomer having two polymerizable groups in one molecule is not particularly limited. For example, divinylbenzene, glycol and methacrylic acid or acrylic acid diester, ethylene glycol dimethacrylate, ethylene glycol diacrylate, propylene glycol Dimethacrylate, propylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol methacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, neopentyl glycol dimethacrylate, neopen Diglycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, tripropylene glycol dimethacrylate, tripropylene glycol diacrylate, trimethylolpropane Monomers having 3 or more polymerizable groups in one molecule such as dimethacrylate, trimethylolpropane diacrylate, tetramethylolmethane dimethacrylate, tetramethylolmethane diacrylate, polypropylene glycol dimethacrylate, polypropylene glycol diacrylate Is not particularly limited, for example Trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, trimethylolethane trimethacrylate, trimethylolethane triacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane triacrylate, pentaerythritol trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate , Pentaerythritol tetraacrylate and the like, and several of them can be mixed. If necessary, other known non-crosslinkable polymerizable monomers and crosslinkable polymerizable monomers can be copolymerized.

  The polymer particles are preferably obtained by copolymerizing the non-crosslinkable polymerizable monomer in a proportion of 90 to 30% by weight and the crosslinkable polymerizable monomer in a proportion of 10 to 70% by weight. . When the proportion of the crosslinkable polymerizable monomer is less than 10% by weight, the resulting polymer particles have poor mechanical strength, poor durability in repeated use, and tend to be unable to perform stable separation analysis. If the proportion of the polymerizable monomer exceeds 70% by weight, it may be difficult to adjust the pore diameter of the polymer particles in some cases.

  In the polymerization, the non-crosslinkable polymerizable monomer and the crosslinkable polymerizable monomer are converted into an inert organic solvent such as dimethyl sulfoxide, xylene, toluene, dioxane, N, N-dimethylformamide, N, N. -It is desirable to dissolve in dimethylacetamide, acetone, tetrahydrofuran or the like.

In the polymerization, a dispersant such as gelatin, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, or hydroxyapatite may be used to stabilize the oil droplets of the monomer in the dispersion medium. Some of the above dispersants do not sufficiently exhibit their functions. In that case, it is effective to add a dispersion aid. As the dispersion aid, generally known surfactants, cationic, anionic and nonionic surfactants can be used, and among them, anionic surfactants are particularly preferable. Examples of the anionic surfactant include sodium alkylbenzene sulfonate, sodium α-olefin sulfonate, sodium alkyl sulfonate, and metal salts thereof. The anionic surfactant is preferably added in an amount of 1 × 10 ^{−4 to} 0.1% by weight with respect to the dispersion medium. If the anionic surfactant is less than 1 × 10 ⁻⁴ wt%, the function as a dispersion aid tends to be difficult to develop. If it exceeds 0.1 wt%, the anionic surfactant itself functions as a dispersant or emulsifier. There is a tendency that good suspension polymerization cannot be performed.

  In the polymerization, a polymerization initiator may be used, and as the polymerization initiator, for example, a peroxide radical initiator or an azo radical initiator can be preferably used. Examples of the peroxide radical initiator include benzoyl peroxide, 2-ethylhexyl perbenzoate, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, lauroyl peroxide, ditert-butyl peroxide, cumene hydroperoxide, Examples include methyl ethyl ketone peroxide, 4,4,6-trimethylcyclohexanone di tert-butyl peroxyketal, cyclohexanone peroxide, methyl cyclohexanone peroxide, acetylacetone peroxide, cyclohexanone di tert-butyl peroxyketal, acetone di-tert-butyl peroxyketal, diisopropyl hydroperoxide, etc. Examples of the azo radical initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis ( , 4-dimethylvaleronitrile), (1-phenylethyl) azodiphenylmethane, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate, 2, 2'-azobis (2-methylbutyronitrile), 1,1'-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis (2,4,4- Trimethylpentane), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2′-azobis (2-methylpropane), and the like. The polymerization initiator is not particularly limited, but it is preferably used in an amount of 0.05 to 10 parts by weight with respect to 100 parts by weight of the monomer having a polymerizable group. When the amount used is less than 0.05 parts by weight, the polymerization time becomes long, and unreacted monomers tend to remain in the polymer particles. When the amount exceeds 10 parts by weight, the polymerization initiator is merely wasted. In addition, it is difficult to control the heat generation during polymerization, and problems such as insufficient molecular chain length tend to occur.

  The polymer particles are preferably porous polymer particles. In order to make the polymer particles porous, it can be obtained by adding a solvent as a pore regulator during the polymerization. As such a solvent, it is desired that the polymerizable monomer is soluble and the resulting polymer is insoluble, and specifically, for example, toluene, xylene, ethylbenzene, diethylbenzene, heptanol, isoamyl Known compounds such as alcohols, ethyl acetate, butyl acetate, dimethyl phthalate, aliphatic phthalates such as diethyl phthalate and diethyl phthalate, ethylene glycol monoethyl ether acetate, hexane, octane and decane can be used. These solvents are properly used depending on the type of polymerizable monomer to be used, and may be used alone or in combination. Further, the blending ratio of these solvents is preferably 5 to 300% by weight, more preferably 20 to 200% by weight, and further preferably 50 to 50% by weight based on the total amount of the polymerizable monomers from the viewpoint of imparting porosity. 100% by weight is added. If the blending ratio is less than 5% by weight or exceeds 300% by weight, it is difficult to obtain desired porosity, and the resulting polymer tends to have poor pressure resistance.

  The porous polymer particles are preferably prepared by polymerization in an aqueous medium. This aqueous medium is basically for emulsifying and dispersing oil droplets that are the basis of porous polymer particles to a desired size, and the amount depends on the type and amount of monomer. Although not generally determined, it is preferably 80 to 400 parts by weight with respect to 100 parts by weight of the polymerizable monomer. If the amount of the aqueous medium is less than 80 parts by weight, the viscosity of the emulsified dispersion tends to increase, making it difficult to adjust the desired oil droplets. If it exceeds 400 parts by weight, the yield of porous polymer particles per production batch However, there are problems such as a decrease in productivity.

The method for introducing the compound having a hydroxamic acid group into the carrier, that is, the method for producing the scavenger of the present invention is not particularly limited. For example, when a carrier having a functional group such as an epoxy group is used. The carrier is dissolved in a solvent together with the compound having a hydroxamic acid group, and the functional group of the carrier is reacted with the hydroxamic acid group. In this case, the compound having a hydroxamic acid group is preferably added in the range of 1 × 10 ^{−2 to} 0.1 mol with respect to 1 g of the carrier. After completion of the hydroxamic acid group introduction reaction, the carrier (collecting agent) into which the hydroxamic acid group has been introduced is removed by filtration or the like, and if necessary, washed with a solvent, water or the like and dried. In addition, the example of introduction shown here is an example, and is not limited to this.

  The solvent used in the introduction reaction is not particularly limited as long as it can dissolve a compound having a hydroxamic acid group, and examples thereof include dimethyl sulfoxide (DMSO), dimethylformamide, pyridine, and tetrahydrofuran. . These solvents may be mixed or used with water. In addition, when the compound having a hydroxamic acid group does not dissolve, the solvent may be heated at a boiling point or lower to dissolve it. The amount of the solvent used may be appropriately determined according to the amount of the carrier or the compound having a hydroxamic acid group, the type of solvent used, etc., and is not particularly limited, but may be in the range of 5 to 500 ml with respect to 1 g of the carrier. preferable.

  Further, the pH of the solvent may be adjusted to facilitate the introduction reaction. For a good reaction between the functional group of the carrier and the compound having a hydroxamic acid group, it is preferable to adjust the pH within the range of 4 to 10. In addition, when the pH is less than 4 or exceeds 10, hydrolysis reaction or the like occurs and the introduction of hydroxamic acid groups tends to be easily inhibited.

  The temperature during the introduction reaction is not particularly limited as long as it is from room temperature to the boiling point of the solvent, but the reaction tends to be slow at 40 ° C. or lower, and the reaction is difficult to control at 90 ° C. or higher. The reaction time may be determined appropriately as long as the reaction proceeds sufficiently, and is not particularly limited, but is preferably 1 to 24 hours, and more preferably 3 to 10 hours.

  Hereinafter, although the collection agent of this invention and its usage are demonstrated concretely by an Example, this invention is not restrict | limited by the said Example.

(Example 1)
<Production of collection agent>
A mixture of 18 g of ethylene glycol dimethacrylate, 21 g of tetramethylolmethane trimethacrylate, 165 g of glycidyl methacrylate, 70 g of n-butyl acetate, 130 g of isoamyl alcohol and 0.9 g of azobisisobutyronitrile was added to 2000 g of 0.5 wt% aqueous methylcellulose solution, Suspension polymerization was performed at 90 ° C. for 10 hours. After cooling the reaction solution, the produced copolymer was filtered, washed with water and methanol to obtain polymer particles. Furthermore, the obtained polymer particles were classified to an average particle size of 50 μm, and then dried at 60 ° C. for 15 hours. In addition, the obtained polymer particle was porous and the quantity of the epoxy group was 3.5 mmol / g.

Next, 2 × 10 ⁻³ mol of DFB (manufactured by Ciba Geigy Japan, Inc., having the above-mentioned chemical structural formula), 5 ml of DMSO and 5 ml of water are added to the flask, and the DFB is dissolved while stirring at 60 ° C. The pH of the solution was adjusted to 9 using an aqueous sodium oxide solution, and 0.1 g of the polymer particles obtained above were added thereto, and the mixture was stirred at 80 ° C. for 4 hours to be reacted.

  After completion of the reaction, the gel substance was filtered, washed with methanol, and dried at 60 ° C. for 3 hours to obtain polymer particles into which DFB was introduced (hereinafter referred to as DFB beads: collection agent). In FIG. 1, the flowchart of collection agent preparation operation is shown.

<Evaluation>
-Adsorption: Concentration of Zr, Mo, W, Ti, and V adjusted to pH 2 with 0.0050 g of the DFB beads obtained above and a sulfuric acid + sodium sulfate buffer solution in a 25 ml sample bottle was 2.0 × 10 ⁻ 10 ml of each ⁶ M high-valent metal solution was added and shaken for 10 minutes (210 rpm) to adsorb each high-valent metal ion to the DFB beads.

Thereafter, the DFB beads are removed by suction filtration, and the metal ion concentration in each filtrate is measured by ICP-OES. From the difference between the measured value and the initial concentration (2.0 × 10 ⁻⁶ M), The metal ion adsorption amount and adsorption rate were calculated. Table 1 shows the pH of the solution when each metal is adsorbed and the adsorption rate of each metal. FIG. 2 shows a flowchart of the adsorption operation.

-Desorption DFB beads adsorbed with each high-valent metal ion in accordance with the above-described adsorption operation are added to 10 ml of an eluent (aqueous sodium hydroxide solution) adjusted to alkaline pH, and shaken for 5 minutes (210 rpm). High valent metal ions were desorbed from

  Thereafter, the DFB beads were removed by suction filtration, the metal ion concentration in each filtrate was measured by ICP-OES, and the recovery rate was determined from the ratio between the measured value and the adsorption amount determined above. Table 2 shows the pH of the eluent when each metal is desorbed and the recovery rate of each metal. FIG. 3 shows a flowchart of the desorption operation.

(Comparative Example 1)
After passing 10 ml of each of the high-valent metal solutions used in Example 1 through a cartridge (Inertsep ME1; manufactured by GL Science Co., Ltd.) in which iminodiacetic acid is fixed to an acrylic resin, this is recovered and the metal ion concentration is measured. As a result, the concentration was the same as the initial concentration, and it was confirmed that each high-valent metal ion was not adsorbed.

The flowchart which shows one Embodiment of the operation flow at the time of producing the collection agent (DFB bead) of this invention. The flowchart which shows one Embodiment of the operation flow at the time of making a collection agent of this invention adsorb | suck a metal. The flowchart which shows one Embodiment of the operation flow at the time of desorbing (recovering) adsorption metal from the collection agent of this invention.

Claims (5)

  A metal ion scavenger having a valence of 3 or more, wherein a compound having a hydroxamic acid group is introduced into a carrier.   The collecting agent according to claim 1, wherein the carrier is polymer particles.   The collection agent according to claim 1 or 2, wherein the pH of the solution containing the metal ions to be collected is 6 or less.   The collection agent according to claim 1 or 2, wherein the solution containing the metal ions to be collected has a pH of 2 or less.   The scavenger according to any one of claims 1 to 4, wherein the compound having a hydroxamic acid group is desferrioxamine B (DFB).

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