JPWO2011052008A1 - Adsorbent manufacturing method - Google Patents

Abstract

The method for producing an adsorbent according to the present invention includes a cerium supporting step of supporting trivalent cerium on a support having a functional group capable of supporting cerium, oxidizing the supported cerium, and determining the valence of the cerium. And a cerium oxidation step to make it tetravalent. For this reason, an adsorbent with high adsorption capability with respect to trivalent arsenic can be manufactured.

Description

  The present invention relates to an adsorbent, a production method thereof, and use thereof.

  In recent years, removal of arsenic from environmental water such as groundwater, soil, hot spring water, marsh lake water, seawater, factory wastewater, mine wastewater, well water, and river water has become an important issue due to problems such as environmental pollution.

  Arsenic is present in various wastewater, river water, well water, etc. Furthermore, since arsenic is also present in the soil, there is a problem when some river water and groundwater are used as tap water. Since arsenic is highly toxic, strict standard values (environmental standard 0.01 ppm, drainage standard 0.1 ppm) are set, and development of a technique for removing trace amounts of arsenic in water is drawing attention.

  As an arsenic removal technique, a precipitation method, an adsorption method, and the like have been proposed. Among them, a method for treating arsenic by coagulation precipitation using an iron salt or an aluminum salt is widely used. However, with these methods, it has been difficult to remove trivalent arsenic (present in arsenous acid). Moreover, in the precipitation method, filtration separation after the precipitation treatment and a large amount of waste treatment are problems, and it is difficult to remove a trace amount of arsenic at low concentration in water.

  On the other hand, in the adsorption method, activated alumina, strong basic anion exchange resin, or the like is used. However, when a strongly basic ion exchange resin is used, there is a problem that the effect of removing arsenic is significantly reduced by coexisting ions. When activated alumina is used, it has a high affinity for arsenic, but dissolves in an acidic region. And problems such as being unable to be used repeatedly.

  Furthermore, these adsorbents have a major problem that trivalent arsenic cannot be directly adsorbed. In particular, in the case of groundwater, since arsenic is almost in the form of trivalent arsenic, pentavalent arsenic (arsenate ions) that are relatively easy to adsorb trivalent arsenic by a pretreatment step in which an oxidizing agent is added. ) Must be adsorbed after conversion.

  Therefore, realizing an adsorbent capable of directly adsorbing both trivalent arsenic and pentavalent arsenic without pretreatment is very valuable in establishing an economical arsenic removal technology. There is.

  In such a flow, it has been conventionally known that rare earth metals, particularly cerium, have a high affinity for arsenic, and its application to treatment of water to be treated containing these has been studied.

  Tetravalent cerium is already known as a component of adsorbent for removing trivalent arsenic in groundwater because it effectively adsorbs trivalent arsenic in water. For example, water-soluble rare earth metal salts are added. In addition, a method for generating and removing a substance to be removed and an insoluble salt is known.

  However, when this method is used, the same problems as the use of the iron and aluminum salts described above arise. Furthermore, since the cost of rare earth metal salts is considerably higher than that of iron and aluminum salts, it is necessary to redissolve the insoluble salts after treatment, and recover and reuse them by solid-liquid separation. The recovery process is complicated and it is difficult to reuse.

  On the other hand, a water-insoluble rare earth metal usually exists as an oxide of a fine powder, and therefore has a drawback that it is difficult to handle in ion exchange operations such as adsorption and elution regeneration.

  In order to improve such drawbacks, several methods for supporting a rare earth metal on a support have been proposed. Here, the method of supporting the rare earth metal on the carrier is mainly classified into two types depending on the water solubility of the rare earth metal reagent used during the supporting step.

  One is a method in which fine particles of water-insoluble rare earth metal oxide are dispersed in a binder polymer resin material through an appropriate organic solvent, and then the binder resin is formed into particles in a poor solvent.

  For example, a method for producing an arsenic or fluorine adsorbent by using a cerium oxide fine particle supported on a resin such as ethylene-vinyl alcohol copolymer (EVOH) using the above method has been proposed (for example, Patent Documents 1 to 3). 4).

  However, in these methods, in order to maintain the mechanical strength of the molded resin spheres, it is usually necessary to support cerium oxide of tens of mass% or more (in many cases up to 85 mass%). In addition, since the cost of the binder resin is relatively high, the material cost is very high. Further, there is a problem that the supported metal leaks during water flow and regeneration. Further, the adsorption capacity varies greatly depending on the size of the raw cerium oxide particles.

  Another method is known in which an aqueous solution of a water-soluble rare earth metal salt is prepared, immersed in a porous inorganic support such as bentonite, alumina, diatomaceous earth, and then fired at a high temperature (for example, supported) (for example, , See Patent Document 5).

  In this method, since it is usually necessary to fire at a temperature of several hundred degrees, the manufacturing method is complicated, and there is a problem that the adsorption capacity of the adsorbent obtained is insufficient.

  In order to improve such a defect, a method of supporting a rare earth metal on a support using complex formation has been proposed (see, for example, Patent Documents 6 to 7). For example, a method for producing an adsorbent using a water-soluble rare earth metal salt aqueous solution and carrying a rare earth metal on a chelate resin by complex formation has been proposed.

  In addition, a particulate cellulose-based adsorbent in which a chelate-forming group or the like is introduced into a particulate cellulose-based base material mainly composed of cellulose having a crystallinity of 80% or more, which does not support a metal on a carrier, has been reported. (For example, refer to Patent Document 8).

Japanese Patent Publication “Japanese Patent Laid-Open No. 2005-288363 (published on October 20, 2005)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2005-28312 (published on February 3, 2005)” Japanese Patent Publication “Japanese Unexamined Patent Application Publication No. 2009-72773 (published on April 9, 2009)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2006-297382 (published on November 2, 2006)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2005-205368 (Released on August 4, 2005)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2004-188307 (published July 8, 2004)” Japanese Patent Publication “JP 2007-185604 (July 26, 2007)” Japanese Patent Publication “JP 2009-13204 (January 22, 2009)”

  However, an adsorbent having higher arsenic adsorption capability than the configurations described in Patent Documents 6 to 8 is desired.

  For example, an adsorbent carrying zirconium has a low adsorptivity with respect to trivalent arsenic, and thus it is difficult to use it for the treatment of groundwater containing a large amount of trivalent arsenic.

  This invention is made | formed in view of said problem, The objective is to implement | achieve the adsorption material with high adsorption capability with respect to trivalent arsenic, and its manufacturing method.

  In order to solve the above problems, the present inventor has the ability to adsorb trivalent arsenic if tetravalent cerium having higher affinity for arsenic than zirconium can be supported on a carrier such as a chelate resin. We thought that a high adsorbent could be manufactured.

  However, there have been no reports of successful examples of supporting tetravalent cerium on a carrier having a functional group held by a chelate structure. This is because an aqueous solution of a water-soluble tetravalent cerium salt has very strong oxidizing power and the aqueous solution is strongly acidic, so that it is difficult to support tetravalent cerium on a carrier. In particular, in the case of a chelate resin derived from a cellulose base material, it is very difficult to support tetravalent cerium because the resin itself is greatly damaged.

  Therefore, the present inventor does not directly support tetravalent cerium on the chelate resin, but first supports trivalent cerium and then oxidizes the supported cerium to tetravalent, so that tetravalent cerium is supported. Has been found to be supported on a chelate resin, and the present invention has been completed.

  That is, the manufacturing method of the adsorbent according to the present invention includes a cerium supporting step of supporting trivalent cerium on a carrier having a functional group capable of supporting cerium, and the supported cerium. And a cerium oxidation step that oxidizes the cerium into a tetravalent valence.

  According to the above method, tetravalent cerium can be easily supported on a carrier without using a tetravalent cerium aqueous solution having very strong oxidizing power and strong acidity. For this reason, there is an effect that an adsorbent having a high adsorption capability for trivalent arsenic can be easily produced without causing any significant damage to the carrier.

  The adsorbent according to the present invention is obtained by the above method according to the present invention, and is characterized in that the carrier is chelated with tetravalent cerium.

  Further, the adsorbent according to the present invention includes a carrier having a functional group capable of carrying cerium and tetravalent cerium carried on the carrier, and the carrier is chelated with tetravalent cerium. It is a feature.

  According to these structures, since the carrier is chelated with tetravalent cerium, an adsorbent having a high adsorption capability for trivalent arsenic can be provided.

  The adsorption treatment method according to the present invention is an adsorption treatment method for arsenic existing in water, and is characterized by using the adsorbent according to the present invention.

  According to the above method, since the adsorbent according to the present invention, which has a high adsorption ability for trivalent arsenic, is used, there is an effect that trivalent arsenic can be efficiently adsorbed.

  As described above, the adsorbent according to the present invention includes a cerium supporting step of supporting trivalent cerium on a support having a functional group capable of supporting cerium, oxidizing the supported cerium, and A cerium oxidation step for converting the number to tetravalent, and the carrier is chelated with tetravalent cerium.

  For this reason, there exists an effect that the adsorption material with high adsorption capability with respect to trivalent arsenic can be provided.

It is a graph which shows the result of the adsorption experiment of trivalent arsenic in an Example. It is a graph which shows the result of the adsorption experiment of pentavalent arsenic in an Example.

  Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto. Further, various physical properties listed in the present specification mean values measured by the methods described in the examples described later unless otherwise specified.

  In the present specification, “main component” means a component having the largest content in terms of mass among the contained components, and “A to B” indicating the range is A or more and B Unless otherwise specified, “ppm” means a value obtained in terms of mass.

(I) Method for Producing Adsorbent In the method for producing an adsorbent according to the present invention, a cerium carrying step of carrying trivalent cerium on a carrier having a functional group capable of carrying cerium, and oxidizing the carried cerium. And a cerium oxidation step for converting the cerium valence to tetravalent. For this reason, an adsorbent carrying tetravalent cerium can be produced without using a tetravalent cerium salt which is difficult to handle.

  Note that the term “supported on a carrier” means “attached to a carrier and provided on the carrier”, and the bond may be a covalent bond or an ionic bond. A chelate bond carrying cerium at two or more locations is preferred.

  Examples of the functional group capable of supporting cerium include iminodiacetic acid group, phosphoric acid group, sulfonic acid group, and phosphonic acid group from the viewpoint of chelating the carrier with cerium.

  Among these, the functional group capable of supporting cerium is more preferably an iminodiacetic acid group from the viewpoint of ease of reaction for supporting cerium.

  The production method according to the present invention may further include a carrier preparation step for producing the carrier. Hereinafter, each step will be described.

[II] Carrier production step The carrier production step may be any method as long as the carrier can be produced.

  Examples of the carrier include a carrier in which a functional group capable of supporting cerium is bonded to a graft chain of a particulate cellulose-based substrate, and a graft chain of a petroleum-based plastic substrate such as polypropylene, polyethylene, and an ethylene-vinyl alcohol copolymer. In addition, a carrier having a functional group capable of supporting cerium bonded thereto can be used.

  In the carrier preparation step in the case of a carrier in which a functional group capable of supporting cerium is bonded to the graft chain of the particulate cellulose substrate, for example, a particulate cellulose group mainly composed of cellulose having a crystallinity of 80% or more. An activation process for activating the material and bringing the activated particulate cellulose-based substrate into contact with the ethylenically unsaturated monomer, thereby graft-polymerizing the ethylenically unsaturated monomer to the particulate cellulose-based substrate. It is preferable to include a graft chain introducing step of introducing a graft chain and a functional group binding step of binding a functional group capable of supporting cerium to the introduced graft chain.

  By using a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more as the base material, an adsorbent excellent in mechanical strength can be obtained because the crystallinity is high. it can. In addition, since cellulose is the most hydrophilic natural product present in nature, it has a low environmental burden, and can provide an inexpensive adsorbent and is hydrophilic. For this reason, the adsorption | suction performance in water can be improved. Furthermore, since it is in the form of particles, conventional adsorption towers for ion exchange / chelating resin spheres, regeneration facilities, etc. can be used as they are.

  Examples of the carrier preparation step in the present embodiment include a method described in JP-A-2009-13204. Hereinafter, as an example of the present embodiment, a carrier preparation step including an activation step, a graft chain introduction step, and a functional group binding step will be described.

<Activation process>
In the present embodiment, first, in the activation step, a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more is activated.

  For activation, for example, cellulose spherical particles are previously placed in a thin plastic bag, this bag is purged several times with an inert gas such as nitrogen and sealed, and then cooled with dry ice in a nitrogen atmosphere. It can be performed by irradiating ionizing radiation under conditions to generate radical active sites.

  The particulate cellulose base material is not particularly limited as long as it is a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. That is, the particulate cellulose-based substrate is preferably composed only of cellulose having a crystallinity of 80% or more, but may contain other components as long as it does not adversely affect the adsorption performance. More specifically, “main component” means that cellulose having a crystallinity of 80% or more in the particulate cellulose base material is 90% or more, more preferably 95% or more, and still more preferably 99%. % Should be included.

  Further, other components that can be included are not particularly limited, and examples thereof include hemicellulose, lignin, and starch.

  The cellulose which is the main component of the particulate cellulose base material is particulate cellulose having a crystallinity of 80% or more. Here, the particulate cellulose having a degree of crystallinity of 80% or more is not limited as long as the mass fraction of the crystalline portion in the particulate cellulose particles is 80% or more. It is meant to include cellulose particles having a crystallinity of 80% or more, cellulose particles comprising 80% or more of microcrystalline cellulose, and the like.

  Here, the microcrystalline cellulose is obtained by removing a non-crystalline part of normal cellulose and purifying, and the crystallinity is close to 100%. The crystallinity can be measured by an X-ray diffraction method.

  The cellulose that is the main component of the particulate cellulose-based substrate may have a crystallinity of 80% or more, more preferably 90% or more, and 95% or more. More preferred is 99% or more.

  Examples of the particulate cellulose base material having a crystallinity of 99% or more include an aggregate of 100% microcrystalline cellulose. Specific examples of the microcrystalline cellulose include, for example, microcrystalline cellulose that is commercially available for pharmaceutical use. Examples of the microcrystalline cellulose include Asola Kasei Chemicals' SEOLUS (registered trademark), SELFIA (registered trademark), and the like. Can be mentioned.

  The shape of the particulate cellulose-based substrate is not particularly limited as long as it is particulate, and may be a spherical shape, an elliptical shape, an indefinite diameter crushing shape, or the like. Among these, the shape of the particulate cellulose-based substrate is more preferably spherical from the viewpoint of mechanical strength.

  Moreover, although the average particle diameter of the said particulate cellulose base material should just be 30-800 micrometers in a dry state, it is more preferable that it is 50-500 micrometers, and it is still more preferable that it is 100-300 micrometers.

  In the present specification, unless otherwise specified, the average particle diameter means a value determined by the following method. First, samples are collected from several locations of a collection of particles as samples. Each sample is observed with an electron microscope, and the entire sample collected from several locations is the largest in diameter of one target particle, that is, the shape of the particle, for a total of 100 or more particles. Measure the dimension in the larger dimension. Among the 100 or more measured values, an average of 60% of measured values excluding 20% in the upper and lower directions is defined as an average particle diameter in the present invention.

  The particulate cellulose-based substrate may be porous cellulose. By using porous cellulose, the obtained cerium-supported particulate adsorbent has functional groups capable of supporting tetravalent cerium and tetravalent cerium introduced in the pores, and the adsorption target is fine. It can flow in the hole. Therefore, it is possible to obtain a cerium-supported particulate adsorbent that is superior in adsorption performance.

  The activation is not particularly limited as long as a radical active site can be generated so that the graft chain can be introduced in the subsequent graft chain introduction step. For example, a method of chemically activating using a radical polymerization initiator, a method of activating by irradiating with ionizing radiation, a method of activating by irradiating with ultraviolet rays, and activating by ultrasonic waves The method, the method of activating by plasma irradiation, etc. can be used.

  Among them, the method of irradiating with ionizing radiation has an advantage that the manufacturing process is simple, safe and low pollution. In addition, the graft chain can be introduced from the surface to the inside of the particulate cellulose-based substrate, and an adsorbent excellent in adsorption capacity can be obtained.

  When activated by irradiating with ionizing radiation, spherical cellulose particles with high crystallinity are typical radiation-decomposable polymers, so doses of ionizing radiation that do not damage particulate cellulose-based substrates Irradiate. Such a dose is preferably 1 to 25 kGy, and more preferably 10 to 20 kGy.

  When the dose of ionizing radiation is 1 kGy or more, a radical active site necessary for a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more can be generated. Moreover, when the dose of ionizing radiation is 25 kGy or less, it is possible to suppress damage applied to the particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. For this reason, the mechanical strength does not decrease, and an adsorbent excellent in chemical stability can be produced. Further, by irradiating with a low dose of ionizing radiation, energy can be saved and the irradiation time can be shortened, so that the manufacturing cost can be reduced.

  Examples of the ionizing radiation include α-rays, β-rays, γ-rays, electron beams, and X-rays. Among them, from the viewpoint of industrial productivity, for example, γ-rays from cobalt-60, electrons from an electron beam accelerator. Lines, X-rays, etc. can be used more suitably. Moreover, when using an electron beam by an electron beam accelerator, it is more preferable to use an electron beam accelerator capable of performing irradiation of a thick material as the electron beam accelerator, and an electron beam having a medium energy to a high energy with an acceleration voltage of 1 MeV or more. An accelerator can be used suitably.

  Moreover, if the particle layer of the particulate cellulose-based substrate is flattened and sealed, for example, in a plastic bag at the time of irradiation, an electron beam can be transmitted even with a medium-low energy electron beam accelerator of 1 MeV or less. Therefore, the particulate cellulose base material can be preferably activated.

  Further, the irradiation with ionizing radiation is more preferably performed in an inert gas atmosphere such as nitrogen gas, neon gas, or argon gas. This is preferable because the graft chain can be effectively introduced.

  Moreover, it is more preferable to perform ionizing radiation irradiation under cooling conditions of -20 to 0 ° C. This is preferable because the graft chain can be effectively introduced.

<Graft chain introduction process>
The particulate cellulose base material activated in the activation step is brought into contact with the ethylenically unsaturated monomer in the graft chain introduction step, and the ethylenically unsaturated monomer is graft polymerized to the particulate cellulose base material. Let Thereby, a graft chain is introduced into the particulate cellulose base material.

  Here, the ethylenically unsaturated monomer refers to a monomer having an ethylenically unsaturated group, that is, a carbon-carbon double bond. Such an ethylenically unsaturated monomer is not particularly limited. For example, an epoxy group-containing ethylenically unsaturated monomer, or a styrene derivative containing an epoxy group, such as styrene or chlorostyrene, is preferably used. Can do. Among these, an epoxy group-containing ethylenically unsaturated monomer can be more suitably used.

  Although it does not specifically limit as an epoxy-group-containing ethylenically unsaturated monomer, For example, following General formula (1)

A monomer having a structure represented by can be suitably used.

Here, in the above general formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represent a substituted or unsubstituted saturated hydrocarbon group or a hydrogen atom. In the saturated hydrocarbon group, some carbon atoms may be substituted with O, N, P, S, or Si. The substituent that can be substituted with the saturated hydrocarbon group is not particularly limited, and examples thereof include an aryl group, an alkyl group, an alkanoyl group, and an oxo group (═O).

Among these, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are more preferably each independently an alkyl group having 1 to 6 carbon atoms or a hydrogen atom.

  In the above general formula, A represents a substituted or unsubstituted saturated hydrocarbon chain, that is, a substituted or unsubstituted divalent saturated hydrocarbon group. In the saturated hydrocarbon chain, some carbon atoms may be substituted with O, N, P, S, or Si. The substituent that can be substituted with the saturated hydrocarbon chain is not particularly limited, and examples thereof include an aryl group, an alkyl group, an alkanoyl group, and an oxo group. In the above general formula, n is 0 or 1.

  Among these, A is more preferably a saturated hydrocarbon chain having 1 to 2 carbon atoms, or one containing at least one oxy group (—O—) in the saturated hydrocarbon chain. Moreover, it is more preferable that it has an oxo group etc. as a substituent.

  More specifically, examples of the ethylenically unsaturated monomer include glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl vinyl ether, 2-vinyloxirane, 2-methyloxiranylmethyl (meth) acrylate, and itacon. Examples thereof include diglycidyl acid, glycidyl pentenoate, glycidyl hexenoate, and glycidyl heptenoate.

  The said ethylenically unsaturated monomer may be used independently and may be used in combination of 2 or more.

  In this embodiment, it is preferable that the ethylenically unsaturated monomer having one ethylenically unsaturated group is graft-polymerized on the particulate cellulose base material, but other monomers are further graft-polymerized. It may be.

  For example, the presence of a polyfunctional monomer having two or more ethylenically unsaturated groups allows the graft chain to have a crosslinked structure. Thereby, the swelling degree of the surface of an adsorbent can be adjusted.

  Examples of the polyfunctional monomer having two or more ethylenically unsaturated groups include polyethylene glycol diacrylate having a number average molecular weight of 400 to 1000 (polyethylene glycol # 400 to 1000 diacrylate), and ethoxylated bisphenol A diacrylate. Divinylbenzene and the like can be preferably used.

  When the polyfunctional monomer having two or more ethylenically unsaturated groups is used, the amount used is 1 to 20 mol% with respect to the ethylenically unsaturated monomer having one ethylenically unsaturated group. Is preferable, and it is more preferable that it is 3-10 mol%.

  In the adsorbent according to the present embodiment, the graft ratio of the graft chain introduced by graft polymerization of the ethylenically unsaturated monomer to the particulate cellulose base material is preferably 100% or more. . When the graft ratio is 100% or more, the supporting ratio of cerium in the obtained adsorbent can be increased. For this reason, an adsorbent with high adsorption capability can be obtained.

  Here, the graft ratio refers to the amount (mass percentage) of the ethylenically unsaturated monomer introduced by graft polymerization with respect to the particulate cellulose-based substrate, and is calculated by the method described in the examples described later. Value.

  The graft ratio is more preferably 150% or more, and particularly preferably 200% or more.

  Further, in the present embodiment, the graft chain introducing step brings the ethylenically unsaturated monomer into the particles by bringing the activated particulate cellulose base material into contact with an emulsion containing the ethylenically unsaturated monomer. It is preferable to introduce a graft chain by graft polymerization to a cellular cellulose base material.

  In emulsion polymerization of an aqueous solvent, the monomer is dispersed in the micelle and the affinity of the monomer with respect to the substrate is improved. Therefore, the radical utilization rate and the polymerization rate are higher than those in solution polymerization with an organic solvent. Thereby, the irradiation dose required for generating radicals in the substrate can be lowered, and the reaction time can be greatly reduced. As a result, an adsorbent with high mechanical strength can be provided.

  In addition, in emulsion polymerization of an aqueous solvent, since an organic solvent is not used during the graft polymerization step, the cost for the process can be reduced, and the environment is friendly and the safety of the process can be improved.

  The amount of the ethylenically unsaturated monomer contained in the emulsion is preferably 30% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 60% by mass or less, based on the total amount of the emulsion, 45 More preferably, it is at least 55% by mass.

  Thereby, the ethylenically unsaturated monomer can be graft-polymerized at a high graft ratio onto a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. Furthermore, the contact time of the activated particulate cellulose base material and the emulsion containing an ethylenically unsaturated monomer can also be shortened.

  Further, the amount of the ethylenically unsaturated monomer is preferably 80% by mass or less based on the total amount of the emulsion, so that the emulsion can be prepared well, can be uniformly dispersed, and is highly stable, which is preferable. .

  The emulsion is more preferably a water-based emulsion, that is, an emulsion containing the ethylenically unsaturated monomer and water. In addition, what is necessary is just to use ion-exchange water, a pure water, an ultrapure water etc. as water used here.

  As a result, the ethylenically unsaturated monomer is dispersed in small micelles, and the utilization rate of radicals and the polymerization rate are increased, so that the particulate cellulose-based base material mainly composed of cellulose having a crystallinity of 80% or more. The ethylenically unsaturated monomer can be graft polymerized with a high graft ratio. Moreover, since an organic solvent is not used in the graft chain introduction step, it is preferable from the viewpoints of reducing process costs, reducing environmental burden, and improving process safety.

  Moreover, it is more preferable that the emulsion further contains 3 to 10% by mass, more preferably 3 to 8% by mass of a surfactant with respect to the ethylenically unsaturated monomer. Thereby, the ethylenically unsaturated monomer can be graft-polymerized at a high graft ratio onto a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. Furthermore, the contact time between the particulate cellulose-based substrate, the activated particulate cellulose-based substrate and the emulsion containing the ethylenically unsaturated monomer can be shortened.

  In addition, as a particularly preferable composition of the emulsion according to the present embodiment, the surfactant is in the range of 3 to 8% by mass, the monomer is in the range of 30 to 80% by mass, for example, the surfactant 5 It can be made into the mass%, the monomer 50 mass%, and the water 45 mass%.

  The surfactant is not particularly limited, and a surfactant usually used in emulsion polymerization can be suitably used.

  Specific examples of such surfactants include, for example, alkyl polyoxyethylene ether, S-alkyl polyoxyethylene ether, alkylphenyl polyoxyethylene ether, N, N′-di (alkanol) alkanamide, amine oxide, and the like. Nonionic surfactants: soap, alkylbenzene sulfonate, alkyl diphenyl ether sulfonate, alkane sulfonate, α-olefin sulfonate, α-sulfo fatty acid methyl, alkyl sulfate, alkyl sulfate (polyoxyethylene) salt Ionic surfactants such as alkyl phosphate salt, N-acylamino acid salt, dialkyldimethylammonium chloride, monoalkyltrimethylammonium chloride; amphoteric surfactants such as sulfobetaine and betaine.

  Further, the method for contacting the activated particulate cellulose-based substrate and the emulsion containing the ethylenically unsaturated monomer is not particularly limited. For example, the activated particulate cellulose-based substrate is The method etc. which are immersed in an emulsion are mentioned.

  The contact time between the activated particulate cellulose-based substrate and the emulsion containing the ethylenically unsaturated monomer is 5 minutes to 8 hours, more preferably 30 minutes to 60 minutes, when a dipping method is used. It is. That is, a high graft rate can be achieved with a short contact time.

  In addition, the reaction temperature, that is, the temperature at which the activated particulate cellulose-based substrate and the emulsion containing the ethylenically unsaturated monomer are brought into contact is 40 to 80 ° C. when the method of dipping is used as the contact method. More preferably, it is 50-60 degreeC.

  Moreover, it is preferable to perform contact with the activated particulate cellulose base material and the emulsion containing an ethylenically unsaturated monomer in inert gas atmosphere, such as nitrogen gas, neon gas, and argon gas. Thereby, reaction of a radical and oxygen can be prevented.

<Functional group binding step>
In the functional group bonding step, a functional group capable of supporting cerium is bonded to the graft chain introduced in the graft chain introducing step.

  The functional group capable of supporting the cerium is introduced by reacting the graft chain with a compound in which the functional group is introduced by reacting with the graft chain. Therefore, when the graft chain has an epoxy group, a compound that can react with the epoxy group to introduce the functional group may be used as the compound.

  As such a compound, for example, when iminodiacetic acid group is introduced, disodium iminoacetate, hydroxyethyliminodiacetic acid, ethylenediaminediacetic acid, L-aspartic acid-N, Ndiacetic acid, etc. are preferably used. Can do.

  Further, for example, when introducing a sulfonic acid group, sodium sulfite, 2-aminoethanesulfonic acid and the like can be suitably used. For example, when introducing a phosphonic acid group, phosphoric acid, phosphorous acid and the like Can be suitably used.

  Moreover, the carrier in the adsorbent according to the present invention is not particularly limited as long as the graft chain has a functional group capable of supporting cerium, and the timing of introduction of the functional group is not particularly limited. Therefore, the carrier having the functional group may be obtained by introducing the functional group into the graft chain after introducing the graft chain into the base material, or the carrier having the particulate cellulose base. Further, it may be obtained by graft polymerization of an ethylenically unsaturated monomer having a functional group capable of supporting cerium.

  Since there are few reactive monomers having an iminodiacetic acid group, when an iminodiacetic acid group is introduced, a reactive monomer such as an epoxy group-containing ethylene is graft-polymerized on a polymer substrate, and then an iminoacetic acid disodium etc. By carrying out a conversion reaction using a reagent, an iminodiacetic acid group can be suitably introduced into the graft polymerization chain. As the ethylenically unsaturated monomer, for example, when an iminodiacetic acid group is introduced, glycidyl methacrylate (GMA) or the like can be preferably used.

  For example, when a phosphate group is introduced, mono (2-methacryloyloxyethyl) acid phosphate, di (2-methacryloyloxyethyl) acid phosphate, mono (2-acryloyloxyethyl) acid phosphate, di (2- Acryloyloxyethyloyl) acid phosphate and the like can be preferably used.

  Furthermore, for example, when introducing a sulfonic acid group, sodium styrene sulfonate, sodium methacryl sulfonate and the like can be suitably used. For example, when introducing a phosphonic acid group, vinyl phosphonic acid, vinyl phenylphosphonic acid can be used. An acid or the like can be preferably used.

  The introduction amount of the functional group capable of supporting cerium, that is, the amount of the functional group capable of supporting cerium contained in 1 g of the carrier is preferably 1 mmol / g or more, and 1.3 mmol / g or more. More preferably, it is more preferably 1.5 mmol / g or more, and particularly preferably 2 mmol / g or more. Further, the amount of the functional group capable of supporting cerium contained in 1 g of the carrier is preferably 10 mmol / g or less, and more preferably 8 mmol / g or less.

  Here, the amount of the functional group capable of supporting cerium contained in 1 g of the carrier is a value calculated by the method described in Examples described later.

  When the amount of the functional group capable of supporting cerium contained in 1 g of the carrier is 1 mmol / g or more, cerium can be sufficiently supported in a short time.

  The reaction conditions in this step may be appropriately selected according to the functional group capable of supporting cerium, and are not particularly limited. For example, when sodium iminodiacetate is introduced, the particulate cellulose base material into which the graft chain is introduced may be introduced into a sodium iminodiacetate aqueous solution to cause a reaction.

  Here, the molar concentration of the aqueous solution of sodium iminodiacetate, that is, the number of moles of sodium iminodiacetate in 1 L of the aqueous solution of sodium iminodiacetate is not particularly limited, but is preferably 0.1 M or more and 0.8 M or less. Yes, more preferably from 0.3M to 0.6M.

  Moreover, reaction temperature becomes like this. Preferably it is 60 degreeC or more and 90 degrees C or less, More preferably, it is 75 degreeC or more and 85 degrees C or less, For example, it can carry out on the conditions for 12 hours at 80 degreeC.

  The carrier to which the functional group capable of supporting cerium bound, obtained as described above, can be easily purified by washing with water and drying, for example.

[I-II] Cerium supporting step The cerium supporting step may be performed under any conditions as long as trivalent cerium can be supported on a carrier having a functional group capable of supporting cerium. For example, in the cerium supporting step, it is preferable to support trivalent cerium on the carrier using an aqueous solution of a trivalent cerium salt that is water-soluble.

  Examples of the water-soluble trivalent cerium salt include cerium trichloride. Cerium trichloride is preferable because it has a weak oxidizing ability and its aqueous solution is neutral, so that it hardly damages the carrier.

  The cerium supporting step using the aqueous solution of the water-soluble trivalent cerium salt can be performed at room temperature. However, by performing the step at a high temperature, the supporting rate and supporting rate of trivalent cerium are greatly improved. be able to. As a result, an adsorbent carrying a large amount of trivalent cerium can be produced in a short time.

  Specifically, the cerium supporting step is preferably performed at 20 ° C. or higher, more preferably at 80 ° C. or higher, and further preferably at 100 ° C. or higher. In addition, when the temperature of the said aqueous solution exceeds 100 degreeC, it can carry out using reaction containers, such as an autoclave, for example, and the temperature of the said aqueous solution can be measured with the temperature sensor etc. with which the reaction container was equipped.

  The supporting rate of cerium in the adsorbent is not particularly limited, but is usually 2 to 30% by mass, preferably 5 to 10% by mass, from the viewpoint of adsorption capacity, removal rate and physical stability.

[I-III] Cerium oxidation step In the cerium oxidation step, the carrier carrying trivalent cerium obtained in the above cerium carrying step is oxidized to convert the cerium carried on the carrier from trivalent to tetravalent. And oxidizing. For example, in the case of the adsorbent in which cerium is supported on the cellulose base described above, the surface color of the adsorbent is changed from white to dark brown as the cerium is changed from trivalent to tetravalent after the oxidation treatment.

  The method of oxidation treatment is not particularly limited. For example, a method of contacting an aqueous solution of an oxidizing agent such as hydrogen peroxide or sodium hypochlorite with a carrier supporting cerium, a method of contacting a carrier supporting cerium with ozone gas Further, it can be carried out by a method of irradiating a carrier supporting cerium with UV or a method of irradiating a carrier supporting cerium with an electron beam (for example, a low energy electron beam).

  In view of safety, ease of handling, cost, and the like, it is preferable to perform an oxidation treatment with an aqueous hydrogen peroxide solution and an aqueous sodium hypochlorite solution.

  A person skilled in the art can appropriately determine various conditions such as processing temperature, time, and oxidant concentration so that there is little damage to the carrier and hardly affects practical use.

(II) Adsorbent The adsorbent according to the present invention includes a carrier having a functional group capable of carrying cerium and tetravalent cerium carried on the carrier, and the carrier is chelated with tetravalent cerium. Yes. The adsorbent can be manufactured by the manufacturing method described above.

  As the carrier, for example, a graft chain is introduced by graft polymerization of an ethylenically unsaturated monomer on a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. By graft polymerizing an ethylenically unsaturated monomer onto a chain having a functional group capable of supporting cerium or a substrate other than cellulose (polypropylene, polyethylene, ethylene-vinyl alcohol copolymer, etc.) A graft chain is introduced, and the graft chain has a functional group capable of supporting cerium.

  Among these, a graft chain is introduced by graft polymerization of an ethylenically unsaturated monomer to a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. It is preferable to have a functional group capable of supporting cerium.

  Examples of the functional group capable of supporting cerium include the above-described iminodiacetic acid group, phosphoric acid group, sulfonic acid group, and phosphonic acid group.

  The shape of the adsorbent is preferably particulate, and examples thereof include a sphere, an ellipse, and an indefinite crushed shape. Among these, a spherical shape is more preferable from the viewpoint of mechanical strength.

  When the adsorbent is particulate, the average particle diameter of the adsorbent may be 100 to 1500 μm, more preferably 100 to 800 μm, and still more preferably 200 to 500 μm. When the average particle diameter is in the above range, conventional adsorption towers for ion exchange / chelating resin spheres, regeneration facilities, etc. can be used as they are.

  The adsorbent may be porous. Thereby, the adsorption target can flow in the pores. Therefore, more excellent adsorption performance can be obtained.

  The adsorbent can be suitably used as an arsenic adsorbent, but can also be suitably used as an adsorbent for anions such as fluorine ions and selenium ions.

  The adsorbent, for example, by contacting with an object to be treated such as an aqueous solution containing arsenic, organic solvent solution, groundwater, soil, hot spring water, marsh lake water, seawater, factory wastewater, mine wastewater, well water, river water, etc. It can be used for removing fluorine and the like.

  The supporting rate of cerium in the adsorbent is not particularly limited, but is usually 2 to 30% by mass, preferably 2 to 20% by mass from the viewpoint of adsorption capacity, removal rate, physical stability, and the like. It is preferable that it is in the range of 5 to 10% by mass.

(III) Adsorption treatment method The adsorption treatment method according to the present invention is an adsorption treatment method for arsenic existing in water, and uses the adsorbent according to the present invention described above.

  As described above, since the adsorbent according to the present invention carries tetravalent cerium, it can adsorb trivalent arsenic efficiently and can be suitably used for removing arsenic.

  In order to adsorb arsenic using the above adsorbent, for example, the adsorbent is introduced into an aqueous solution containing these and stirred, shaken, or passed through the column or adsorption tower filled with the adsorbent. As a result, the arsenic and the adsorbent are brought into contact with each other. By these treatments, harmful ions such as arsenic are adsorbed on the adsorbent.

  The adsorbent can be reused by treating the adsorbed arsenic with an appropriate eluent and oxidizing agent (e.g., elution with sodium hydroxide and reoxidation with sodium hypochlorite). is there.

  As described above, the method for producing an adsorbent according to the present invention includes a cerium supporting step of supporting trivalent cerium on a carrier having a functional group capable of supporting cerium, oxidizing the supported cerium, and And a cerium oxidation step for converting the valence of cerium to tetravalence.

  According to the above method, tetravalent cerium can be easily supported on a carrier without using a tetravalent cerium aqueous solution having very strong oxidizing power and strong acidity. For this reason, there exists an effect that the adsorption material with high adsorption capability with respect to trivalent arsenic can be manufactured simply.

  Further, since no tetravalent cerium aqueous solution is used, damage to the carrier can be suppressed, and as a result, an adsorbent excellent in mechanical strength and stability can be produced.

  The method for producing an adsorbent according to the present invention further includes a carrier preparation step of preparing the carrier having a functional group capable of supporting cerium, and the carrier preparation step includes cellulose having a crystallinity of 80% or more. An activation step of activating the particulate cellulose-based substrate as a main component, and bringing the activated particulate cellulose-based substrate into contact with the ethylenically unsaturated monomer allows the ethylenically unsaturated monomer to It is preferable to include a graft chain introducing step of introducing a graft chain by graft polymerization onto a particulate cellulose base material, and a functional group binding step of bonding a functional group capable of supporting cerium to the introduced graft chain.

  According to the above method, since the carrier is prepared by performing graft polymerization on the particulate cellulose base material, the size of the carrier is arbitrarily controlled by appropriately adjusting the graft ratio and the size of the cellulose particles. can do. That is, according to the above method, it is possible to produce a spherical adsorbent that is easy to control the structure, has excellent stability, and has an arsenic adsorption ability superior to that of conventional arsenic adsorption resin balls.

  Furthermore, in the method for producing an adsorbent according to the present invention, the graft chain introduction step includes bringing the activated particulate cellulose base material into contact with an emulsion containing an ethylenically unsaturated monomer, thereby producing the ethylenic material. It is preferable to introduce a graft chain by graft polymerization of an unsaturated monomer to the particulate cellulose base material.

  According to the above method, since emulsion polymerization of an aqueous solvent is performed, the utilization rate of radicals and the polymerization rate are higher than those of solution polymerization using an organic solvent. Thereby, the irradiation dose required for generating radicals in the substrate can be lowered, and the reaction time can be greatly reduced. As a result, an adsorbent with high mechanical strength can be provided.

  In the method for producing an adsorbent according to the present invention, the graft chain introduction step is preferably performed so that the graft rate is 100% or more.

  According to the above method, since the cerium supporting rate in the obtained adsorbent can be increased, an adsorbent with high adsorbing ability can be obtained.

  Furthermore, in the method for producing an adsorbent according to the present invention, in the activation step, the particulate cellulose-based substrate is activated by irradiating the particulate cellulose-based substrate with ionizing radiation, and the ionizing property. The radiation is preferably γ-rays, electron beams, or X-rays, and the dose is preferably 10 to 20 kGy.

  According to the above method, damage to the particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more can be suppressed, so that the mechanical strength does not decrease and the chemical stability is reduced. It is possible to produce an adsorbent excellent in the above.

  Moreover, in the manufacturing method of the adsorbent which concerns on this invention, it is preferable that the crystallinity degree of the said cellulose base material is 95% or more.

  According to the above method, an adsorbent excellent in mechanical strength and chemical stability can be produced.

  Furthermore, in the method for producing an adsorbent according to the present invention, the functional group capable of supporting cerium is at least one selected from the group consisting of an iminoniacetic acid group, a phosphoric acid group, a sulfonic acid group, and a phosphonic acid group. It is preferable that

  According to the said method, since it can introduce | transduce into a graft chain easily, an adsorbent can be manufactured more simply.

  Moreover, in the manufacturing method of the adsorbent which concerns on this invention, it is preferable that the content rate of the said functional group which can carry | support cerium in the said support | carrier is 1 mmol / g or more.

  According to the above method, an adsorbent capable of sufficiently supporting cerium in a short time can be produced.

  In the method for producing an adsorbent according to the present invention, in the cerium supporting step, it is preferable to support trivalent cerium on a carrier using a trivalent water-soluble cerium salt.

  According to the above method, since trivalent cerium can be easily supported on the carrier, the adsorbent can be more easily produced.

  In the method for producing an adsorbent according to the present invention, the cerium supporting step is preferably performed at 20 ° C. or higher.

  According to the above method, since trivalent cerium can be easily supported on the carrier, the adsorbent can be more easily produced.

  In the method for producing an adsorbent according to the present invention, the cerium supporting step is preferably performed at 80 ° C. or higher.

  According to the above method, trivalent cerium can be easily supported by the carrier, and thus the adsorbent can be more easily produced.

  In the method for producing an adsorbent according to the present invention, in the cerium supporting step, it is preferable to support the carrier so that the cerium supporting rate of the carrier is in the range of 2 to 20% by mass.

  According to the above method, an adsorbent excellent in adsorption capacity, removal rate and physical stability can be produced.

  In the method for producing an adsorbent according to the present invention, the cerium oxidation step includes the steps of contacting a carrier supporting cerium with an aqueous oxidant solution, contacting the carrier supporting cerium with ozone gas, and a carrier supporting cerium. It is preferable to carry out by a method of irradiating UV or a method of irradiating an electron beam onto a carrier supporting cerium.

  According to the said method, since trivalent cerium can be oxidized easily, an adsorbent can be manufactured more simply.

  The adsorbent according to the present invention is obtained by the above method according to the present invention, and is characterized in that the carrier is chelated with tetravalent cerium.

  Further, the adsorbent according to the present invention includes a carrier having a functional group capable of carrying cerium and tetravalent cerium carried on the carrier, and the carrier is chelated with tetravalent cerium. It is a feature.

  According to these structures, since the carrier is chelated with tetravalent cerium, an adsorbent having a high adsorption capability for trivalent arsenic can be provided.

  In the adsorbent according to the present invention, the carrier has graft chains introduced by graft polymerization of an ethylenically unsaturated monomer to a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. It is preferable that the graft chain has a functional group capable of supporting cerium.

  According to the above configuration, it is possible to provide a spherical adsorbent that is easy to control the structure, has excellent stability, and has an arsenic adsorption ability superior to that of conventional arsenic adsorption resin balls.

  Moreover, in the adsorbent which concerns on this invention, it is preferable that an average particle diameter exists in the range of 100-1500 micrometers.

  According to the said structure, the conventional adsorption tower for ion exchange or a chelate resin ball | bowl, reproduction | regeneration equipment, etc. can be used as it is.

  Furthermore, the adsorbent according to the present invention is preferably an adsorbent for adsorbing at least one anion selected from the group consisting of arsenic ions, fluorine ions, and selenium ions.

  The adsorbent according to the present invention is preferably an adsorbent for adsorbing arsenic dissolved in soil, groundwater, tap water, seawater, industrial wastewater, hot spring water, or mine wastewater.

  The adsorption treatment method according to the present invention is an adsorption treatment method for arsenic existing in water, and is characterized by using the adsorbent according to the present invention.

  According to the above method, since the adsorbent according to the present invention, which has a high adsorption ability for trivalent arsenic, is used, there is an effect that trivalent arsenic can be efficiently adsorbed.

  In the adsorption treatment method according to the present invention, it is preferable to use a column or an adsorption tower packed with the adsorbent.

  According to the above method, trivalent arsenic can be adsorbed more efficiently.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited thereto. First, determination methods of “graft ratio”, “amount of functional group capable of supporting cerium contained in 1 g of carrier”, and “cerium support ratio” in Examples are shown below.

<Graft ratio>
The graft ratio, that is, the amount (mass percentage) of the ethylenically unsaturated monomer introduced by graft polymerization with respect to the particulate cellulose base material was determined by the following method.

After graft polymerization, the graft polymer of the particulate cellulose base material into which the ethylenically unsaturated monomer has been introduced is immersed in an organic solvent such as methanol or acetone for 48 hours to remove unreacted ethylenically unsaturated monomer and homopolymer. Removed. Thereafter, the graft polymer of the particulate cellulose base material was further immersed in water for 24 hours, washed with water, and dried at 50 ° C. for 24 hours. The graft ratio is calculated from the weight (Wg) of the graft polymer of the particulate cellulose base material after drying and the dry weight (W0) of the particulate cellulose base material before introducing the ethylenically unsaturated monomer. Calculated by
Graft ratio (%) = ((Wg−W0) / W0) × 100
<Amount of functional group capable of supporting cerium contained in 1 g of carrier>
The amount of the functional group capable of supporting cerium contained in 1 g of the carrier is the mass (Wg, unit: g) of the graft polymer of the particulate cellulose base material obtained by the above method, and the functional group capable of supporting cerium. It was calculated by the following equation from the weight (Wp, unit: g) of the support obtained by binding an equivalent (M) and a functional group capable of supporting cerium, washing and drying.

Amount of functional group capable of supporting cerium contained in 1 g of carrier (mmol / g) = {((Wp−Wg) / M) / Wp} × 1000
<Cerium loading>
The amount of cerium supported, that is, the amount of cerium supported (mass percentage) relative to the mass of the adsorbent is calculated from the mass of the carrier used (Wp) and the mass of the adsorbent obtained (Wq) by the following equation. did.
Cerium loading (mass%) = ((Wq−Wp) / Wq) × 100
[Example 1]
Cellulose fine particles composed of only microcrystalline cellulose (diameter: 200 to 300 μm, product name: SELFIA (registered trademark), manufactured by Asahi Kasei Chemicals Corporation, crystallinity: 99% or more) are placed in a thin plastic bag. The bag was purged several times with nitrogen and sealed.

  The bag was cooled with dry ice and irradiated with ionizing radiation having a dose of 20 kGy with an industrial high-performance electron accelerator (product name: EPS-800, manufactured by NHV Corporation) to generate radical active sites.

  The sample after irradiation was immediately immersed in an emulsion solution of glycidyl methacrylate substituted with nitrogen prepared in advance.

  The composition of the emulsion used was 3% by mass of a surfactant (trade name: Tween 20, manufactured by Wako Reagent Co., Ltd.), 30% by mass of glycidyl methacrylate, and 67% by mass of water.

  The graft ratio was 250%.

  The glycidyl methacrylate-grafted cellulose particles obtained under the above conditions were put into a 0.5 M aqueous solution of sodium iminoacetate and reacted at 80 ° C. for 12 hours. The obtained sample was washed with water and dried to obtain a carrier (diameter: 400 to 500 μm). The functional group density of iminodiacetic acid groups in this carrier was about 2.2 mol / g.

Thereafter, the carrier was immersed in a 0.1 M cerium chloride (CeCL ₃ ) solution at about 80 ° C. for 8 hours to obtain an adsorbent carrying trivalent cerium. The loading of trivalent cerium in the adsorbent was 9% by mass.

The adsorbent carrying trivalent cerium is brought into contact with a 20% by mass aqueous solution of H ₂ O ₂ at room temperature for 24 hours, and then washed with pure water and dried to obtain tetravalent cerium having a dark brown color. A supported adsorbent (hereinafter referred to as “CCM-As”) was obtained. The adsorption rate of cerium in the adsorbent was 9% by mass.

[Arsenic batch adsorption experiment]
Using the adsorbent CCM-As obtained in Example 1, the following arsenic batch adsorption experiment was performed.

<Trivalent arsenic>
A commercially available trivalent arsenic standard solution was diluted with pure water to prepare a 5 ppm trivalent arsenic solution (initial pH: around 6.5).

  The adsorbent CCM-As 0.1 g was put into 100 mL of 5 ppm arsenic aqueous solution and stirred at room temperature for 24 hours. Thereafter, arsenic in the supernatant was measured with an ICP emission spectrometer, and the amount of arsenic adsorbed was determined from the initial concentration in the solution and the residual concentration after treatment.

  As a comparison, an example is included in a commercially available arsenic adsorption resin ball (trade name: Read-As, manufactured by Nihonkaikai), an unpublished international patent application (application number: PCT / JP2009 / 52796) previously filed by the present applicant. The adsorption experiment was also performed under the same conditions for the zirconium-supported resin spheres described as 1 (Zr loading: 15%, hereinafter referred to as “CCM-F”).

  The result is shown in FIG. As shown in FIG. 1, the adsorbent CCM-As has an adsorption capacity for trivalent arsenic equal to or higher than that of a commercially available arsenic adsorption resin sphere. That is, in the adsorbent CCM-As, almost all arsenic in water can be removed after the treatment with the adsorbent, and a water supply standard of 0.01 ppm can be achieved.

  Further, it was found that the adsorbent CCM-As exhibits a much higher adsorption capacity as compared with CCM-F.

  In addition to the above experiment, an adsorption experiment was performed under the same conditions using the adsorbent before oxidation treatment in Example 1 (referred to as “before CMM-As oxidation treatment”), but most of the trivalent arsenic was. It did not adsorb. From this result, it is considered that the adsorption mechanism of the adsorbent CCM-As is adsorbed after oxidizing trivalent arsenic existing in water to pentavalent arsenic once.

<Pentavalent arsenic>
A commercially available pentavalent arsenic standard solution was diluted with pure water to prepare a 5 ppm pentavalent arsenic solution (initial pH: around 6.5).

  The adsorbent CCM-As 0.1 g was put into 100 mL of 5 ppm arsenic aqueous solution and stirred at room temperature for 24 hours. Thereafter, arsenic in the supernatant was measured with an ICP emission spectrometer, and the amount of arsenic adsorbed was determined from the initial concentration in the solution and the residual concentration after treatment.

  As a comparison, an adsorption experiment was carried out under the same conditions for a commercially available arsenic adsorption resin ball (trade name: Read-As, manufactured by Nihonkaikai), CCM-F, and a commercially available alumina adsorbent (manufactured by Wako Pure Chemical Industries, Ltd.).

  The results are shown in FIG. As shown in FIG. 2, the adsorbent CCM-As showed an adsorption capacity equal to or higher than that of pentavalent arsenic compared to a commercially available arsenic adsorbent resin ball and a commercially available alumina adsorbent. That is, in the adsorbent CCM-As, almost all arsenic in water can be removed after the treatment with the adsorbent, and a water supply standard of 0.01 ppm can be achieved.

  From these results, it was found that the adsorbent according to the present invention has a high adsorption capacity for both trivalent arsenic and pentavalent arsenic.

  As described above, the adsorbent of the present invention has an excellent adsorption capacity for arsenic and the like, and purifies groundwater, factory wastewater, hot spring water, mine wastewater, etc. contaminated with these harmful substances. It was confirmed that this was very advantageous.

  Moreover, since the adsorbent produced in this example is produced by ionizing radiation, particularly electron beam irradiation using an electron accelerator, it is practically easily mass-produced industrially.

  In view of factors such as the manufacturing process, adsorption capacity, regeneration speed, and environmental aspects, the adsorbent of the present invention can replace the conventional arsenic adsorbent.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The adsorbent of the present invention can be suitably used as an adsorbent for various harmful substances such as arsenic.

The present invention relates to a method for producing an adsorbent .

Claims (21)

A cerium supporting step of supporting trivalent cerium on a carrier having a functional group capable of supporting cerium;
A cerium oxidation step of oxidizing the supported cerium so that the valence of the cerium is tetravalent;
The manufacturing method of the adsorbent characterized by including. Further comprising a carrier production step of producing the above carrier having a functional group capable of carrying cerium,
The carrier production process includes
An activation step of activating a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more;
Graft chain introduction in which an activated particulate cellulose-based substrate is brought into contact with an ethylenically unsaturated monomer to graft-polymerize the ethylenically unsaturated monomer onto the particulate cellulose-based substrate to introduce a graft chain. Process,
The method for producing an adsorbent according to claim 1, further comprising a functional group binding step of binding a functional group capable of supporting cerium to the introduced graft chain.   In the graft chain introduction step, the activated particulate cellulose-based substrate is brought into contact with an emulsion containing an ethylenically unsaturated monomer to graft-polymerize the ethylenically unsaturated monomer onto the particulate cellulose-based substrate. The method for producing an adsorbent according to claim 2, wherein graft chains are introduced.   The method for producing an adsorbent according to claim 2 or 3, wherein the graft chain introduction step is performed so that a graft ratio is 100% or more. In the activation step, the particulate cellulose-based substrate is activated by irradiating the particulate cellulose-based substrate with ionizing radiation,
The said ionizing radiation is a gamma ray, an electron beam, or a X-ray, The dose is 10-20 kGy, The manufacturing method of the adsorption material of any one of Claims 2-4 characterized by the above-mentioned.   The method for producing an adsorbent according to any one of claims 2 to 5, wherein the crystallinity of the cellulose-based substrate is 95% or more.   The functional group capable of supporting cerium is at least one selected from the group consisting of an iminoniacetic acid group, a phosphoric acid group, a sulfonic acid group, and a phosphonic acid group. A method for producing the adsorbent according to claim 1.   The method for producing an adsorbent according to any one of claims 1 to 7, wherein the content of the functional group capable of supporting cerium in the carrier is 1 mmol / g or more.   The method for producing an adsorbent according to any one of claims 1 to 8, wherein in the cerium supporting step, trivalent cerium is supported on a carrier using a trivalent water-soluble cerium salt.   The method for producing an adsorbent according to any one of claims 1 to 9, wherein the cerium supporting step is performed at 20 ° C or higher.   The method for producing an adsorbent according to any one of claims 1 to 10, wherein the cerium supporting step is performed at 80 ° C or higher.   The method for producing an adsorbent according to any one of claims 1 to 11, wherein in the cerium supporting step, the carrier is supported so that a cerium supporting rate of the carrier is in a range of 2 to 20 mass%.   In the above cerium oxidation step, a method in which a carrier supporting cerium is brought into contact with an oxidizing agent aqueous solution, a method in which a carrier supporting cerium is brought into contact with ozone gas, a method in which UV is applied to a carrier supporting cerium, or a carrier containing cerium. The method for producing an adsorbent according to any one of claims 1 to 12, wherein the adsorbent is irradiated by an electron beam onto the carrier.   An adsorbent obtained by the method according to any one of claims 1 to 13, wherein the carrier is chelated with tetravalent cerium.   An adsorbent comprising a carrier having a functional group capable of supporting cerium and tetravalent cerium supported on the carrier, wherein the carrier is chelated with tetravalent cerium.   In the above carrier, a graft chain is introduced by graft polymerization of an ethylenically unsaturated monomer to a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more, and the graft chain is cerium. The adsorbent according to claim 15, which has a functional group capable of supporting   The adsorbent according to any one of claims 14 to 16, wherein an average particle diameter is in a range of 100 to 1500 µm.   The adsorption according to any one of claims 14 to 17, which is an adsorbent for adsorbing at least one anion selected from the group consisting of arsenic ions, fluorine ions, and selenium ions. Wood.   The adsorbent for adsorbing arsenic dissolved in soil, groundwater, tap water, seawater, industrial wastewater, hot spring water, or mine wastewater, according to any one of claims 14-18. Adsorbent. A method for adsorbing arsenic present in water,
An adsorption treatment method using the adsorbent according to any one of claims 14 to 19.   21. The adsorption treatment method according to claim 20, wherein a column or an adsorption tower filled with the adsorbent is used.

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