JP5045269B2 - Particulate cellulose-based adsorbent and method for producing the same - Google Patents

Description

  The present invention relates to a particulate cellulose-based adsorbent and a method for producing the same, and particularly to a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more and a chelate-forming group and / or an ion-exchange group. The present invention relates to a particulate cellulose-based adsorbent into which is introduced and a method for producing the same.

  Metalloids such as boron and germanium are often contained in industrial wastewater because they are used in a wide range of fields. Such a semimetal has properties as a semiconductor and is an element group indispensable for the development of new materials in high-tech industries and the like, so it is desired to recover it from industrial wastewater. As a method for recovering these metalloids from wastewater, several adsorption methods such as a coagulation precipitation method, an ion exchange adsorption method, and a chelate adsorption method are known. Among these, the chelate adsorption method having selective adsorption property utilizes the property that boron or germanium forms a complex with a compound (polyhydroxy compound) containing a plurality of hydroxyl groups such as sugar chains and alcohols. As a resin in which a functional group containing a hydroxyl group is introduced into an insoluble polymer, for example, an adsorbent using a polystyrene-based adsorption resin into which a methylglucamine group is introduced has been proposed. However, this polystyrene-based chelate adsorbing resin has the disadvantages that since the matrix is hydrophobic, the adsorption rate of boron, germanium, etc. is low and the adsorption capacity is not sufficient. Furthermore, there are problems that the production method of a methylglucamine-type polystyrene chelate adsorbing resin currently on the market is complicated and expensive, and it is difficult to dispose after disposal because it is made from petroleum.

  In contrast, cellulose, which is the most abundant polysaccharide in nature and widely used in various fields as a cheap and renewable resource, is a polyhydroxy compound having a large number of structurally hydrophilic hydroxyl groups. Therefore, development of a glucamine-type cellulose chelate adsorption resin has been proposed (see, for example, Non-Patent Document 1). However, the glucamine-type cellulose chelate adsorbing resin reported in Non-Patent Document 1 is produced by a chemical grafting method in which a base material is chemically activated and grafted, and has a low graft ratio and a glucamine functional group. There is a problem that the base density is low. Furthermore, since a chemical method is used, there are problems such as the safety and handling of the manufacturing process.

On the other hand, compared with chemical grafting, the radiation grafting method does not use a radical polymerization initiator, but introduces any reactive monomer as a graft chain into the polymer substrate. There is an advantage that a monomer can be grafted. There has been reported a method in which a reactive monomer is graft-polymerized in an emulsion solution onto a polymer substrate activated by irradiation (see, for example, Patent Document 1). Although not related to the adsorbent resin, some studies on radiation grafting to cellulose fibers have been reported (for example, see Non-Patent Documents 2 and 3).
JP 2005-344047 A (released on December 15, 2005) Yoshinari Inukai (Y. Inukai), 9 others, "Removal of boron (III) by N-methylglucamin-type cellulose derivatives with higher adsorption rate" (2004), Analytical Chimica Acta, Vol. 51.P261-265. (Elsevier Science) JL Williams and two others, `` Graft copolymers as Elastomeric Fibers- I Synthesis of the Graft Copolymers '' (1975), International Journal of Applied Radiation and Isotopes, Vol.26.P159-168. (Pergamon Press) F. Khan, 2 others, “Gamma radiation-induced emulsion graft copolymerization of MMA onto jute fiber” (2002), Advances in Polymer Teclmology, Vol.21.P132-140. (Wiley Periodicals)

  However, it has been reported that graft chains can be obtained at a high graft ratio by the radiation grafting method using emulsion graft polymerization described in Patent Document 1 and Non-Patent Documents 2 and 3, both of which are amorphous. It is a fibrous or film-like cellulose containing a relatively large portion.

  Cellulose containing a relatively large amount of non-crystalline parts is not sufficient in mechanical strength to be used in an ion exchange / chelating resin sphere adsorption tower, regeneration equipment, etc., and also has chemical stability. Not enough. In addition, the fibrous or film-like cellulose chelate adsorption resin is very expensive and has a different shape from conventional polystyrene adsorbent resin particles. It is difficult to use towers and regeneration facilities as they are. Therefore, it is difficult to use a large amount of fibrous or film-like cellulose chelate adsorption resin as a substitute for conventional polystyrene adsorbent resin particles.

  Accordingly, a cellulose-based adsorbent resin that has sufficient mechanical strength, has a certain chemical stability as a base material for the adsorbent, and is in the form of particles and has a high degree of crystallinity as a base material. Is desired.

  However, the spherical particles of cellulose having a high degree of crystallinity have a low radical yield at the crystal interface, and a high graft rate cannot be obtained. Although it is known that the radical yield of the cellulose base material is increased by irradiating a high dose of radiation, there is a problem that the base material is seriously damaged. In particular, since crystalline cellulose is a typical radiolytic polymer, in the case of spherical particles of cellulose having a high degree of crystallinity, if the graft dose exceeds 30 kGy, the base material is greatly damaged and the mechanical strength is significantly reduced. To do. However, a dose of at least 50 kGy is usually required to obtain the grafting rate of the reactive monomer necessary for the particulate cellulose-based adsorbent.

  Further, in methods other than the radiation grafting method, an example in which a reactive monomer is polymerized at a high graft ratio using cellulose spherical particles having a high crystallinity as a base material has not been known yet.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to use a spherical particle of cellulose having a high degree of crystallinity as a base material, without destroying the original structure and strength of the base material, and to react the reactive monomer. An object of the present invention is to provide a particulate cellulose-based adsorbent that is efficiently polymerized and imparted with desired adsorption characteristics, and a method for producing the same.

  As a result of diligent studies to solve the above problems, the present inventors are a typical radiolytic polymer, and therefore have no idea of applying the radiation grafting method. Even when the spherical particles were irradiated with a low dose of radiation that normally did not reach activation, the present invention succeeded in obtaining a high graft ratio by graft polymerization in an emulsion containing a high concentration of reactive monomer. It came to complete.

  In order to solve the above-mentioned problem, the particulate cellulose-based adsorbent according to the present invention has a chelating group and / or an ion-exchange group on a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more. A particulate cellulose-based adsorbent into which groups are introduced, wherein the chelate-forming group and / or ion-exchange group is introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose-based substrate. The graft ratio of the graft chain is 100% or more.

  According to the above configuration, the adsorption tower for conventional ion exchange / chelate resin spheres is excellent in chemical stability and mechanical strength, has low environmental burden, is inexpensive, and can improve the adsorption performance in water. In addition, it is possible to realize an adsorbent that can be used as it is, such as regeneration equipment.

  In the particulate cellulose-based adsorbent according to the present invention, the average density of the chelate-forming groups and / or ion exchange groups is preferably 1.0 mmol / g or more.

  When the average density of the chelate-forming groups and / or ion exchange groups is 1.0 mmol / g or more, a particulate cellulose-based adsorbent having an excellent adsorbing ability as an adsorbent can be obtained.

  In the particulate cellulose-based adsorbent according to the present invention, the hydrophobic monomer is preferably an epoxy group-containing ethylenically unsaturated monomer.

  In the particulate cellulose-based adsorbent according to the present invention, the epoxy group remaining in the graft chain is preferably dioled.

  Since the remaining epoxy group is converted into a diol, such a diol can also contribute to the formation of a chelate, so that the adsorption ability of the particulate cellulose-based adsorbent can be further improved.

  The particulate cellulose-based adsorbent according to the present invention preferably has an average particle size of 100 to 1500 μm.

  When the average particle diameter is 100 to 1500 μm, it is possible to reduce the resistance when the column is passed through. Further, conventional adsorption towers for ion exchange / chelating resin spheres, regeneration facilities, etc. can be used as they are.

  In the particulate cellulose-based adsorbent according to the present invention, the chelate-forming group is a glucamine group, a diol group, a polyol group, an iminodiacetic acid group, a polyamine group, an amidoxime group, a dithiocarbamic acid group, a thiourea group, or an aminophosphate group. It is preferable that

  The chelate-forming group is a glucamine group, a diol group, a polyol group, an iminodiacetic acid group, a polyamine group, an amidoxime group, a dithiocarbamic acid group, a thiourea group, or an aminophosphate group. Can be granted.

  In the particulate cellulose-based adsorbent according to the present invention, the particulate cellulose-based substrate is preferably made of cellulose having a crystallinity of 95% or more.

  The metalloid adsorbent according to the present invention is preferably composed of the particulate cellulose-based adsorbent. The metalloid adsorbent according to the present invention is preferably a boron adsorbent, a germanium adsorbent or an arsenic adsorbent.

  Use as a semi-metal adsorbent is very advantageous when industrially removing these semi-metals and separating, concentrating and recovering them as useful resources.

  In order to solve the above-mentioned problem, the method for producing a particulate cellulose-based adsorbent according to the present invention comprises adding a chelate-forming group and / or a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more. Or a method for producing a particulate cellulose-based adsorbent into which an ion-exchange group has been introduced, which comprises an activation step of activating a particulate cellulose-based substrate whose main component is cellulose having a crystallinity of 80% or more; A graft chain introducing step of bringing an activated particulate cellulose base material into contact with an emulsion containing a hydrophobic monomer, and grafting the hydrophobic monomer onto the particulate cellulose base material to introduce a graft chain; And a functional group binding step of binding a chelate-forming group and / or an ion exchange group to the introduced graft chain, and the hydrophobicity contained in the emulsion The amount of Nomar is characterized in that 80 wt% or less greater than 30% by weight relative to the emulsion total amount.

  According to the above configuration, the mechanical strength is excellent, the load on the environment is low, the cost is low, and the adsorption performance in water can be improved. Conventional adsorption towers for ion exchange / chelate resin balls, regeneration facilities, etc. An adsorbent that can be used as is can be realized.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the emulsion preferably further contains 3 to 10% by weight of a surfactant with respect to the hydrophobic monomer.

  According to the above configuration, the mechanical strength is excellent, the load on the environment is low, the cost is low, and the adsorption performance in water can be improved. Conventional adsorption towers for ion exchange / chelate resin balls, regeneration facilities, etc. An adsorbent that can be used as it is can be more suitably realized.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the activation step is performed by ionizing a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more with a dose of 1 to 30 kGy. It is preferable to irradiate with radiation.

  When the dose of ionizing radiation is 30 kGy or less, there is an effect that damage applied to the particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more can be suppressed.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, it is preferable to irradiate the particulate cellulose-based substrate having a water content of more than 10% and 50% or less with ionizing radiation.

  By irradiating the particulate cellulose base material having a water content of more than 10% and 50% or less with ionizing radiation, the graft rate of graft chains introduced can be further increased in the subsequent graft chain introduction step.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the emulsion is preferably a water-based emulsion.

  Since the emulsion is an aqueous emulsion and does not use an organic solvent, it is preferable from the viewpoints of reducing process costs, reducing environmental burden, and improving process safety.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the hydrophobic monomer is preferably an epoxy group-containing ethylenically unsaturated monomer.

  The method for producing a particulate cellulose-based adsorbent according to the present invention preferably further includes a step of diolating the epoxy group remaining in the graft chain after the functional group binding step.

  Since the remaining epoxy group is converted into a diol, such a diol can also contribute to the formation of a chelate, so that the adsorption ability of the particulate cellulose-based adsorbent can be further improved.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the particulate cellulose-based substrate preferably has an average particle diameter of 30 to 800 μm.

  When the average particle diameter of the particulate cellulose-based substrate is 30 to 800 μm, a particulate cellulose-based adsorbent having a desired average particle diameter can be obtained.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the chelate-forming group is a diol group, a polyol group, an iminodiacetic acid group, a polyamine group, an amidoxime group, a dithiocarbamic acid group, a thiourea group, or an aminophosphate group. It is preferable that

  The chelate-forming group is a diol group, a polyol group, an iminodiacetic acid group, a polyamine group, an amidoxime group, a dithiocarbamic acid group, a thiourea group, or an aminophosphate group, thereby imparting selective adsorption to the adsorbent. Can do.

  In the method for producing a particulate cellulose-based adsorbent according to the present invention, the ionizing radiation is preferably γ-rays, electron beams, or X-rays.

  When the ionizing radiation is γ-rays, electron beams, or X-rays, the manufacturing process is simple, safe, and low pollution.

  As described above, the particulate cellulose-based adsorbent according to the present invention introduces a chelate-forming group and / or an ion-exchange group into a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more. In the particulate cellulose-based adsorbent, the chelate-forming group and / or ion-exchange group is bonded to a graft chain introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose-based substrate. Since the graft ratio of the graft chain is 100% or more, the mechanical strength is excellent, the environmental load is low, the cost is low, and the adsorption performance in water can be improved. There is an effect that it is possible to realize an adsorbent that can use an adsorption tower for ion exchange / chelate resin spheres, a regeneration facility, and the like.

  As described above, the method for producing a particulate cellulose-based adsorbent according to the present invention includes a chelating group and / or ion-exchange on a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more. A method for producing a particulate cellulose-based adsorbent in which a group is introduced, the activation step of activating a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more, and activation A graft chain introducing step of bringing the resulting particulate cellulose base material into contact with an emulsion containing a hydrophobic monomer, grafting the hydrophobic monomer onto the particulate cellulose base material, and introducing a graft chain; A functional group binding step of binding a chelate-forming group and / or an ion exchange group to the grafted chain, and the amount of the hydrophobic monomer contained in the emulsion Since it has a constitution that is greater than 30% by weight and less than or equal to 80% by weight with respect to the total amount of the emulsion, it has excellent mechanical strength, has a low environmental load, is inexpensive, and can improve the adsorption performance in water. There is an effect that it is possible to realize an adsorbent that can use a conventional adsorption tower for an ion exchange / chelate resin sphere, a regeneration facility, and the like.

  Hereinafter, the present invention will be described in the order of (I) a particulate cellulose-based adsorbent and (II) a method for producing a particulate cellulose-based adsorbent.

(I) Particulate Cellulosic Adsorbent The particulate cellulose adsorbent according to the present invention has a chelating group and / or an ion on a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. A particulate cellulose-based adsorbent into which an exchange group has been introduced, wherein the chelate-forming group and / or ion-exchange group is introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose-based substrate. The graft ratio of the graft chain is 100% or more.

  Here, the graft ratio refers to the amount (weight percentage) of the hydrophobic monomer introduced by graft polymerization with respect to the particulate cellulose-based substrate, and the value calculated by the method described in the examples described later. Say.

(I-1) Particulate Cellulosic Base Material The particulate cellulose-based adsorbent according to the present invention has a chelating group and / or a particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. An ion exchange group is introduced. By using a particulate cellulose base material mainly composed of cellulose with a crystallinity of 80% or more as the base material, the crystallinity is high, so that it has chemical stability and excellent mechanical strength. Adsorbent can be obtained. In addition, since cellulose, which is a natural material, is used, an environmentally friendly and inexpensive adsorbent can be obtained, and since it is hydrophilic, the adsorption 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.

  The particulate cellulose base material may be 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 the 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.

  Cellulose, which is the main component of the particulate cellulose-based substrate, 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 weight fraction of the crystalline part in the particulate cellulose particles is 80% or more. This is intended to include cellulose particles having a crystalline part having a crystallinity of 80% or more, cellulose particles having 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%.

  Cellulose, which is the main component of the particulate cellulose base material, 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, for example, Asahi Kasei Chemicals' Theolas (registered trademark), Serfia (registered trademark). Etc.

  Further, 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 further 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 set of particles serving as samples. Each sample is observed with an electron microscope, and the entire sample taken 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 base material may be porous cellulose. By using porous cellulose, the resulting cellulose-based adsorbent has chelate-forming groups and / or ion-exchange groups introduced into the pores, and the adsorption target may flow through the pores. it can. Therefore, it is possible to obtain a particulate cellulose-based adsorbent having better adsorption performance.

(I-2) Graft chain The particulate cellulose-based adsorbent according to the present invention is a chelate-forming group and / or ion-exchange group in a graft chain introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose-based substrate. A group is attached.

  Here, the hydrophobic monomer is not particularly limited as long as it is a hydrophobic monomer having one ethylenically unsaturated group. The hydrophobic monomer having one ethylenically unsaturated group is not particularly limited. For example, an epoxy group-containing ethylenically unsaturated monomer; styrene; a styrene derivative such as chlorostyrene, or the like is preferably used. it can. Among these, an epoxy group-containing ethylenically unsaturated monomer can be more suitably used.

  The epoxy group-containing ethylenically unsaturated monomer is not particularly limited. For example, the following general formula

A monomer having a structure represented by can be suitably used. Here, in the said general formula, R < ¹ >, R < ² >, R < ³ >, R < ⁴ >, R < ⁵ > and R < ⁶ > show a saturated hydrocarbon group or a hydrogen atom which has a substituent each independently. In the saturated hydrocarbon group, some carbon atoms may be substituted with O, N, P, S, or Si. The substituent 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 an alkyl group having 1 to 6 carbon atoms or a hydrogen atom.

  In the general formula, A represents a saturated hydrocarbon chain having or not having a substituent, that is, a divalent saturated hydrocarbon group having or not having a substituent. In the saturated hydrocarbon chain, some carbon atoms may be substituted with O, N, P, S, or Si. The substituent 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 hydrophobic monomer include glycidyl (meth) allylate, allyl glycidyl ether, glycidyl vinyl ether, 2-vinyloxirane, 2-methyloxiranylmethyl (meth) acrylate, and diglycidyl itaconate. Glycidyl pentenoate, glycidyl hexenoate, glycidyl heptenoate and the like.

  The hydrophobic monomers may be used alone or in combination of two or more. In the present invention, it is sufficient that the hydrophobic monomer having one ethylenically unsaturated group is graft-polymerized on the particulate cellulose base material, and other monomers may be further graft-polymerized. . For example, by allowing a polyfunctional monomer having two or more ethylenically unsaturated groups to coexist, a structure in which graft chains are crosslinked can be obtained. Thereby, the swelling degree of the surface of a particulate cellulose type adsorbent can be adjusted. As the polyfunctional monomer having two or more ethylenically unsaturated groups, for example, polyethylene glycol # 400 to 1000 diacrylate, ethoxylated bisphenol A diacrylate, divinylbenzene and the like can be suitably used. When using the polyfunctional monomer which has 2 or more of the said ethylenically unsaturated groups, it is preferable that the usage-amount is 1-20 mol% with respect to the hydrophobic monomer which has one said ethylenically unsaturated group. More preferably, it is 3-10 mol%.

  In the particulate cellulose-based adsorbent according to the present invention, the graft ratio of graft chains introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose-based substrate is 100% or more. When the graft ratio is 100% or more, the average density of the chelate-forming groups and / or ion exchange groups of the obtained particulate cellulose-based adsorbent can be increased. Therefore, a particulate cellulose-based adsorbent having a high adsorption capacity can be obtained.

  The graft ratio may be 100% or more, more preferably 150% or more, and further preferably 200% or more.

(I-3) Functional group The particulate cellulose-based adsorbent according to the present invention may constitute an adsorbent on a graft chain introduced by graft polymerization of the hydrophobic monomer on the particulate cellulose-based substrate. Possible functional groups are attached. Here, the functional group is not particularly limited as long as it can form an adsorbent by being introduced, but a chelate-forming group, an ion exchange group, or the like is preferably used. Can do. That is, the particulate cellulose-based adsorbent according to the present invention has a chelate-forming group introduced, an ion-exchange group introduced, or both a chelate-forming group and an ion-exchange group introduced. It is more preferable.

  The chelate-forming group used in the present invention is not particularly limited as long as it is a group that forms a chelate compound with an adsorption target. For example, it is composed of a glucamine group, a diol group, a polyol group, a polyol and a nitrogen atom. Group, iminodiacetic acid group, polyamine group, amidoxime group, dithiocarbamic acid group, thiourea group, aminophosphoric acid group and the like can be suitably used. Here, the polyol group means a group having 3 or more hydroxyl groups.

  The chelate-forming group is introduced by reacting the graft chain with a compound capable of binding the chelate-forming group 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 chelate-forming group may be used as the compound.

  Examples of such compounds include N-methylglucamine (N-methyl-D-(-)-glucamine); 2,2′-iminodiethanol; 3-amino-1,2-propanediol, di-2-propanol. Examples thereof include diol group-containing compounds such as amines.

  The ion exchange group used in the present invention may be any ion exchange group that is usually used as an ion exchange group. For example, a cation exchange group such as an acidic hydroxyl group, a carboxyl group, or a sulfo group. An anion exchange group such as an amino group, an imino group, and an ammonium group. The method for introducing the ion exchange group is not particularly limited, and a conventionally known method can be suitably used.

  The average density of the chelate-forming groups and / or ion-exchange groups, that is, the amount of chelate-forming groups and / or ion-exchange groups contained in 1 g of the particulate cellulose-based adsorbent is 1.0 mmol / g or more. Preferably, it is 1.3 mmol / g or more, more preferably 1.5 mmol / g or more.

  When the average density of the chelate-forming group and / or ion-exchange group is 1.0 mmol / g or more, a particulate cellulose-based adsorbent having adsorbability that can be used as an adsorbent can be obtained.

  In the case where the graft chain has an epoxy group, it is more preferable that the epoxy group remaining after the introduction of the chelate-forming group and / or the ion exchange group is dioled. Thereby, since this diol can also contribute to chelate formation, the adsorption capacity of the particulate cellulose-based adsorbent can be further improved.

(I-4) Particulate cellulose-based adsorbent The shape of the particulate cellulose-based adsorbent according to the present invention is not particularly limited as long as it is particulate, as in the case of the particulate cellulose substrate. Any shape, indefinite diameter crushing shape, etc. may be used. Among these, the shape of the particulate cellulose-based adsorbent is more preferably spherical from the viewpoint of mechanical strength.

  Moreover, the average particle diameter of the particulate cellulose-based adsorbent according to the present invention may be 100 to 1500 μm, more preferably 100 to 800 μm, and further 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 particulate cellulose-based adsorbent according to the present invention may be porous. Thereby, the adsorption target can flow in the pores. Therefore, more excellent adsorption performance can be obtained.

  The particulate cellulose-based adsorbent of the present invention can adsorb various metalloids, metalloid compounds, metals or metal compounds by appropriately selecting the introduced chelate group. Examples of the metalloid include boron, germanium, tellurium, selenium, and arsenic. Examples of the metal include Cu, Cd, Hg, Zn, Fe, Cr, Mn, Ca, Mg, and Na. Among these, the particulate cellulose adsorbent of the present invention can be suitably used as a boron adsorbent, a germanium adsorbent, an arsenic adsorbent, a heavy metal adsorbent, and the like.

  In particular, when the particulate cellulose-based adsorbent according to the present invention is one in which a glucamine group or a polyol group is introduced as a chelate-forming group, the particulate cellulose-based adsorbent includes boron, germanium, arsenic in water. Can be more suitably used as an adsorbent for adsorbing. In such a case, the adsorption performance can be further improved by providing a diol group that forms a chelate compound with boron, germanium, or the like by diol-forming the remaining epoxy group. In addition, since cellulose itself is a hydrophilic polyhydroxy compound, it is possible to provide an adsorbent such as boron, germanium, and arsenic having a high adsorption ability.

  The particulate cellulose-based adsorbent into which the chelate-forming group according to the present invention is introduced is, for example, an aqueous solution, organic solvent solution, soil, seawater, factory wastewater containing metalloid, metalloid compound, metal, metal compound, It can be used for removing harmful metals, recovering useful metals, separating and producing specific metals from multi-component metal systems, etc. by bringing them into contact with treatment objects such as hot spring water and mine wastewater.

  In addition, the particulate cellulose-based adsorbent of the present invention can be obtained by appropriately selecting the ion exchange group introduced, and various metal ions; biopolymers such as amino acids, vitamins, proteins, nucleic acids, sugars; ionic dyes Etc. can be adsorbed and separated. In particular, since cellulose is highly hydrophilic, it can be suitably used for the adsorption and separation of biopolymers.

  The method for bringing the particulate cellulose-based adsorbent according to the present invention into contact with the object to be treated is not particularly limited. For example, the particulate cellulose-based adsorbent according to the present invention is introduced into the object to be treated and stirred. Alternatively, a method of shaking and mixing, a method of passing the treatment target through a column or adsorption tower packed with the particulate cellulose-based adsorbent according to the present invention, and the like can be used.

  The particulate cellulose adsorbent after adsorbing metalloid, metal, etc. can be regenerated by contacting the metallurgical metal, metal, etc. with an eluent such as dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid. it can. Also, the eluted metalloid, metal, etc. can be recovered simultaneously. The particulate cellulose-based adsorbent after elution can be used again as an adsorbent after washing with pure water.

(II) Production method of particulate cellulose-based adsorbent The particulate cellulose-based adsorbent according to the present invention has hitherto been difficult to introduce graft chains at a high graft ratio, and has a crystallinity of 80% or more. A graft chain is introduced at a high graft ratio into a particulate cellulose base material mainly composed of cellulose. Such a high graft rate is considered to be achieved by activating the particulate cellulose-based substrate and then graft polymerization in an emulsion containing a high concentration of reactive monomer. Therefore, the manufacturing method of this particulate cellulose adsorbent is also included in the present invention.

  That is, the particulate cellulose-based adsorbent according to the present invention includes an activation step of activating a particulate cellulose-based substrate mainly composed of cellulose having a crystallinity of 80% or more, and an activated particulate cellulose. A graft chain introducing step of bringing a graft substrate into contact with an emulsion containing a hydrophobic monomer, grafting the hydrophobic monomer onto the particulate cellulose substrate, and introducing the graft chain; And a functional group binding step of binding a chelate-forming group and / or an ion exchange group to the emulsion, and the amount of the hydrophobic monomer contained in the emulsion is greater than 30% by weight and less than 80% by weight based on the total amount of the emulsion .

(II-1) Activation Step In the method for producing a particulate cellulose-based adsorbent according to the present invention, first, in the activation step, a particulate cellulose-based substrate mainly comprising cellulose having a crystallinity of 80% or more. Activate.

  Here, the particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more is as described in the above (I-1), and therefore the description thereof is omitted here.

  The activation is not particularly limited as long as the radical active site can be generated in the subsequent graft chain introduction step so that the graft rate of the graft chain to be introduced is 100% or more. , 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, a method of activating by ultrasound A method of activation by plasma irradiation 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. Further, the graft chain can be introduced from the surface to the inside of the particulate cellulose-based substrate, and an adsorbent having an excellent adsorption ability 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. The dose is preferably 1 to 30 kGy, more preferably 1 to 25 kGy, and still 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 30 kGy or less, there is an effect that it is possible to suppress damage applied to the particulate cellulose base material mainly composed of cellulose having a crystallinity of 80% or more. Therefore, it is possible to produce a particulate cellulose-based adsorbent excellent in chemical stability without lowering mechanical strength. Further, by irradiating with a low dose of ionizing radiation, energy and irradiation time can be saved, 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 these, from the viewpoint of industrial productivity, for example, γ-rays and electron beams from cobalt-60. An electron beam, an X-ray, etc. by an accelerator 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. Further, when the particle layer of the particulate cellulose base material 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 to low energy electron beam accelerator of 1 MeV or less. Therefore, the particulate cellulose base material can be preferably activated.

  Further, it is more preferable that the ionizing radiation is irradiated to the particulate cellulose base material having a moisture content of more than 10% and 50% or less. Thereby, the graft ratio of the graft chain introduced can be further increased in the subsequent graft chain introducing step. The reason why the graft ratio can be increased by irradiating the particulate cellulose-based substrate having a water content of more than 10% and not more than 50% is not clear, but the inside of the particulate cellulose-based substrate is not clear. For example, in the case of a particulate cellulose-based substrate containing microcrystalline cellulose, it is considered that water molecules distributed between the microcrystalline bodies generate radicals by irradiation to increase the yield of radical active sites. The moisture content of the particulate cellulose base material that is irradiated with ionizing radiation is more preferably 15 to 35%, and particularly preferably 15 to 25%. On the other hand, when the water content exceeds 50%, it becomes difficult to prepare a particulate cellulose base material containing such an amount of water.

  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.

(II-2) Graft chain introduction step The particulate cellulose base material activated in the activation step is brought into contact with an emulsion containing a hydrophobic monomer in the graft chain introduction step, and the hydrophobic monomer is introduced into the particles. Graft-polymerize on a cellulosic base material. Thereby, a graft chain is introduced into the particulate cellulose base material.

  Here, since the “hydrophobic monomer” is as described in the above (I-2), the description is omitted here.

  The amount of the hydrophobic monomer contained in the emulsion used in this step is preferably more than 30% by weight and 80% by weight or less, more preferably 40 to 60% by weight, more preferably 45%. More preferably, it is -55 weight%. Thereby, a hydrophobic monomer can be graft-polymerized with a high graft ratio on 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 a hydrophobic monomer can also be shortened. On the other hand, when the amount of the hydrophobic monomer is more than 80% by weight based on the total amount of the emulsion, it is difficult to prepare an emulsion, and dispersion is not uniform or stability is not preferable.

  The emulsion is more preferably a water-based emulsion, that is, an emulsion containing the hydrophobic 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 hydrophobic monomer is dispersed in small micelles, and the utilization rate of the radicals and the polymerization rate are increased, so that the degree of crystallinity is high in the particulate cellulose base material mainly composed of cellulose of 80% or more. Hydrophobic monomers can be graft polymerized at a graft rate. Further, since an organic solvent is not used in the graft chain introduction step, it is preferable from the viewpoint of reducing process costs, reducing environmental burden, and improving process safety.

  Moreover, it is preferable that the said emulsion contains 3-10 weight% of surfactant further with respect to a hydrophobic monomer, More preferably, it is 3-8 weight%. Thereby, a hydrophobic monomer can be graft-polymerized with a high graft ratio on 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 hydrophobic monomer can also be shortened.

  The surfactant that can be used in this step is not particularly limited, and a surfactant that is usually used in emulsion polymerization can be suitably used. Specific examples of such surfactants include 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 salts, N-acyl amino acid salts, dialkyldimethylammonium chlorides and monoalkyltrimethylammonium chlorides; amphoteric surfactants such as sulfobetaines and betaines.

  The method for contacting the activated particulate cellulose substrate with the emulsion containing the hydrophobic monomer is not particularly limited. For example, the activated particulate cellulose substrate is added to the emulsion. The method of immersing etc. can be mentioned.

  The contact time between the activated particulate cellulose-based substrate and the emulsion containing the hydrophobic monomer is 5 minutes to 8 hours, more preferably 30 minutes to 60 minutes, when the immersion method is used. . In the present invention, a high graft ratio 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 hydrophobic monomer are brought into contact with each other is preferably 40 to 80 ° C. when the immersion method is used. Is 50-60 ° C.

  Further, the contact between the activated particulate cellulose base material and the emulsion containing the hydrophobic monomer is preferably performed in an inert gas atmosphere such as nitrogen gas, neon gas, or argon gas. Thereby, reaction of a radical and oxygen can be prevented.

(II-3) Functional group bonding step In the functional group bonding step, a chelate-forming group and / or an ion exchange group is bonded to the graft chain introduced in the graft chain introducing step. Here, since the chelate-forming group and / or the ion-exchange group are as described in (I-3), the description thereof is omitted here.

  The reaction conditions in this step may be appropriately selected according to the graft chain, chelate forming group and / or ion exchange group, and are not particularly limited.

(II-4) Other Further, in the method for producing a particulate cellulose-based adsorbent according to the present invention, when an epoxy group-containing ethylenically unsaturated monomer is used as the hydrophobic monomer, after the functional group binding step, It is preferable to include a step of diol-forming the epoxy group remaining in the graft chain.

  The method for diol-forming the epoxy group remaining in the graft chain is not particularly limited, and a conventionally known method may be appropriately selected. Specifically, a method of washing with 0.1 to 1 mol / l dilute hydrochloric acid can be suitably used.

  The particulate cellulose-based adsorbent after adsorbing metalloid, metal, etc. can be regenerated by contacting the metalloid, metal, etc. with an eluent such as dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid. it can. It is considered that the remaining epoxy group is converted into a diol during the regeneration process. For this reason, the particulate cellulose-based adsorbent according to the present invention has a preferable characteristic that the adsorption capacity does not decrease even when it is repeatedly used, and conversely, the adsorption capacity improves as the number of uses increases.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. First, the determination method of the graft ratio in an Example and a comparative example is shown below.

<Graft ratio>
The graft ratio of the particulate cellulose-based adsorbent, that is, the amount (weight percentage) of the hydrophobic monomer introduced by graft polymerization with respect to the particulate cellulose-based substrate was determined by the following method.

After graft polymerization, the cellulose-based particles into which the hydrophobic monomer was introduced were immersed in an organic solvent such as methanol and acetone for 48 hours to remove unreacted hydrophobic monomer and homopolymer. Thereafter, the cellulose particles were further immersed in water for 24 hours, washed with water, and dried at 50 ° C. for 24 hours. The graft ratio was calculated from the weight (W _g ) of the cellulose-based particles after drying and the dry weight (W ₀ ) of the particulate cellulose-based substrate before introducing the hydrophobic monomer by the following formula.
Graft ratio (%) = ((W _g −W ₀ ) / W ₀ ) × 100
<Average density of chelate forming groups and / or ion exchange groups>
The average density of the chelate-forming group and / or ion-exchange group is the weight (W _g ) of the cellulosic particles determined by the above method, the molecular weight (M) of the chelate-forming group and / or ion-exchange group, the chelate-forming group and / or The weight was calculated from the following formula from the weight (W _p ) of the particulate cellulose-based adsorbent obtained by binding ion exchange groups, washing and drying.
Average density of chelating groups and / or ion exchange groups (mmol / g) =
((W _p −W _g ) / M) / W _p
[Example 1]
A particulate cellulose-based adsorbent having the same particle diameter as that of a commercially available boron-adsorbing resin was produced using cellulose fine particles composed of only commercially available microcrystalline cellulose as a particulate cellulose-based substrate.

<Manufacture of particulate cellulose adsorbent>
10 g of cellulose fine particles composed of only commercially available microcrystalline cellulose (manufactured by Asahi Kasei Chemicals, SELFIA (registered trademark) 203) (average particle size: 150 to 300 μm) are used as the particulate cellulose base material, and water is sprayed on the surface. Was sprayed to obtain a water-containing particulate cellulose base material having a water content of 20%.

  The obtained water-containing particulate cellulosic substrate was placed in a thin plastic bag, which was purged several times with nitrogen and sealed. Subsequently, the water-containing particulate cellulose-based substrate is irradiated with 20 kGy of electron beam using an electron beam accelerator (NEPS Corporation, EPS-800) under a cooling condition with dry ice in a nitrogen atmosphere to generate radical active sites. I let you.

  The particulate cellulose-based substrate after irradiation was immediately immersed in an emulsion containing glycidyl methacrylate (GMA) previously prepared and nitrogen-substituted, and reacted at 50 ° C. for 1 hour. The composition of the emulsion used was 4% by weight of a surfactant (manufactured by Wako Pure Chemical Industries, Ltd., Tween 20), 40% by weight of glycidyl methacrylate, and 56% by weight of water based on the total amount of the emulsion liquid.

  The graft ratio of glycidyl methacrylate was 270% to 280%. The grafting rate of glycidyl methacrylate, that is, the number of epoxy functional groups, determines the glucamination conversion rate to be introduced later. Generally, when the graft ratio of glycidyl methacrylate is 100% or more, the amount of glucamine group that effectively acts as a functional group that adsorbs boron or the like can be obtained.

  A 20% N-methyl D-(-)-glucamine (NMG) aqueous solution was prepared from the particulate cellulose-based adsorbent grafted with glycidyl methacrylate at a graft ratio of 270% to 280% obtained as described above. And reacted at 80 ° C. for 12 hours to obtain a glucamine type particulate cellulose adsorbent.

  The glucamine-type particulate cellulose-based adsorbent obtained in this example was washed with water and methanol sequentially and then dried to obtain the desired particulate cellulose-based adsorbent (diameter 400 to 500 μm, average particle diameter 450 μm). . Moreover, the average density of the chelate-forming group was 1.7 mmol / g.

<Structural analysis of particulate cellulose adsorbent>
The result of observing the particulate cellulose-based adsorbent obtained in this example with an electron microscope (JEOL Ltd., JXA-840A) is shown in FIG. In FIG. 1, (A) is an electron micrograph showing the entire particulate cellulose-based adsorbent, (B) is an electron micrograph showing the surface structure of the particulate cellulose-based adsorbent, and (C) is particulate. It is an electron micrograph which shows the cross-sectional structure of a cellulose type adsorbent. 1 (B) and (C), it was found that the particulate cellulose-based adsorbent obtained in the present invention has a porous structure in which the liquid easily flows.

[Example 2]
Example 1 except that the composition of the emulsion used was 5% by weight of surfactant (Tween 20 manufactured by Wako Pure Chemical Industries, Ltd.), 50% by weight of glycidyl methacrylate, and 45% by weight of water with respect to the total amount of the emulsion liquid. Similarly, a particulate cellulose-based adsorbent was produced.

  The graft ratio of glycidyl methacrylate was 341.66%, and a high graft ratio was achieved. Moreover, the average particle diameter of the obtained particulate cellulose-based adsorbent was 600 μm. Moreover, the average density of the chelate-forming group was 1.8 mmol / g.

[Comparative Example 1]
The same particulate cellulose base material as used in Example 1 was irradiated with an electron beam in the same manner as in Example 1 to generate radical active sites.

  The particulate cellulose-based substrate after irradiation was immediately immersed in a 30% glycidyl methacrylate (GMA) methanol solution prepared in advance and purged with nitrogen, and reacted at 50 ° C. for 1 hour. The graft ratio of glycidyl methacrylate was 30%.

[Comparative Example 2]
Example 1 except that the composition of the emulsion used was 2% by weight of a surfactant (manufactured by Wako Pure Chemical Industries, Ltd., Tween 20), 20% by weight of glycidyl methacrylate, and 78% by weight of water based on the total amount of the emulsion liquid. Similarly, a particulate cellulose-based adsorbent was produced. The graft ratio of glycidyl methacrylate was 74%.

[Comparative Example 3]
Example 1 except that the composition of the emulsion used was 1% by weight of surfactant (manufactured by Wako Pure Chemical Industries, Ltd., Tween 20), 10% by weight of glycidyl methacrylate, and 89% by weight of water based on the total amount of the emulsion liquid. Similarly, a particulate cellulose-based adsorbent was produced. The graft ratio of glycidyl methacrylate was 50%.

Example 3
Using the particulate cellulose-based adsorbent obtained in Example 1, a batch adsorption test of boron, germanium, and arsenic was performed.

<Boron batch adsorption test>
A commercially available 1000 ppm boron standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with a buffer solution to prepare a 100 ppm boron aqueous solution, and the pH was variously adjusted with hydrochloric acid and sodium hydroxide. 0.1 g of the particulate cellulose-based adsorbent produced in Example 1 was added to 100 ml of 100 ppm boron aqueous solution and stirred at room temperature for 24 hours.

  Thereafter, the amount of boron in the supernatant was measured with an IPC emission spectrometer, and the amount of boron adsorbed was determined from the amount of boron before addition of the particulate cellulose-based adsorbent and the amount of boron after stirring for 24 hours. A result is shown in Table 1 with the result of having performed the same measurement about commercially available boron adsorbent CRB-05 and GRY-L. In Table 1, “CCM” indicates the particulate cellulose-based adsorbent produced in Example 1.

<Batch adsorption test of germanium>
A commercially available 1000 ppm germanium standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with a buffer solution to prepare a 100 ppm germanium aqueous solution, and the pH was variously adjusted with hydrochloric acid and sodium hydroxide. 0.1 g of the particulate cellulose-based adsorbent produced in Example 1 was added to 100 ml of a 100 ppm germanium aqueous solution and stirred at room temperature for 24 hours.

  Thereafter, the amount of germanium in the supernatant was measured with an IPC emission spectrometer, and the amount of germanium adsorbed was determined from the amount of germanium before addition of the particulate cellulose-based adsorbent and the amount of germanium after stirring for 24 hours. The results are shown in Table 2 together with the results of performing the same measurement on commercially available germanium adsorbents CRB-05 and GRY-L.

<Arsenic (trivalent) batch adsorption test>
A commercially available 100 ppm arsenic standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) is diluted with a buffer solution to prepare arsenic aqueous solutions having six concentrations in the range of 0.1 ppm to 30 ppm. Adjusted to .5. 0.5 g of the particulate cellulose-based adsorbent produced in Example 1 was added to 100 ml arsenic aqueous solution of each concentration and stirred at room temperature for 24 hours.

  The amount of arsenic adsorbed was determined by hydrogenating the arsenic in the supernatant and measuring the amount of arsenic with an IPC emission spectrometer. The difference between the amount of arsenic after stirring for 24 hours and the amount of arsenic before addition of particulate cellulose-based adsorbent was calculated. The amount of arsenic adsorption was determined. The amount of arsenic adsorption at each arsenic concentration is shown in Table 3.

  Since the particulate cellulose-based adsorbent of the present invention has a chelate-forming group at a high density, and further comprises a hydrophilic polymer and is easily adapted to water, as shown in Tables 1, 2 and 3, boron, germanium, arsenic Easily adsorbed. Even when compared with the results of Comparative Example 4 described later, the particulate cellulose-based adsorbent of the present invention is about 1.6 times the commercially available boron adsorbent for boron, and about 1 of the commercially available germanium adsorbent for germanium. .3 adsorption amount was shown. Further, from the result of the arsenic adsorption test, it was found that the particulate cellulose-based adsorbent of the present invention adsorbs the target substance with high efficiency even in a low concentration solution of the adsorption target substance.

[Comparative Example 4]
Boron in the same manner as in Example 3 for commercially available methylglucamine-type chelate adsorbent resin spheres (CRB-05, manufactured by Mitsubishi Chemical Corporation) and glucamine-type cellulose-based chelate fibers (GRY-L, manufactured by Kirest Corporation) And a batch adsorption test of germanium. The results are shown in Tables 1 and 2.

Example 4
Using the particulate cellulose-based adsorbent obtained in Example 1, a boron column adsorption / elution experiment was conducted.

<Boron column adsorption experiment>
First, the particulate cellulose adsorbent obtained in Example 1 was conditioned. The conditioned particulate cellulose-based adsorbent was packed in a slurry state into a column having an inner diameter of 16 mm and a height of 77.5 mm (bed volume: about 15 ml). Boron leakage curves were determined at pH 8.0.

  The column flow experiment was performed at room temperature using two kinds of flow rates (2.5 ml / min (SV = 10), 12.5 ml / min (SV = 50)) using a mini pump. As a sample solution, a 100 ppm boron phosphate buffer solution (pH 8) was used. A result is shown in FIG. 2 with the result of having performed the same measurement about the commercially available boron adsorbent.

<Boron column elution experiment>
In the elution experiment, a column after saturated adsorption of boron was used. After flowing pure water at 12.5 ml / min for 30 minutes, 0.1 mol / l HCl solution was flowed at 12.5 ml / min to elute adsorbed boron. I did an experiment. A result is shown in FIG. 3 with the result of having performed the same measurement about the commercially available boron adsorbent.

  As shown in FIGS. 2 and 3, the particulate cellulose-based adsorbent of the present invention has a chelate-forming group at a high density, and is made of a hydrophilic polymer and easily adaptable to water. Also in the adsorption experiment, the leakage was slower than the commercial product and the boron adsorption ability was excellent. Further, the rate of recovery treatment of adsorbed boron with hydrochloric acid was faster than the commercial product, and the amount of hydrochloric acid used for recovery was less than that of the commercial product. From this result, it was found that the particulate cellulose adsorbent of the present invention is easier to regenerate than the commercially available boron adsorbent.

[Comparative Example 5]
Boron in the same manner as in Example 4 was used for a methylglucamine-type chelate-adsorbed styrene resin sphere (CRB-05, 400 μm, manufactured by Mitsubishi Chemical Corporation), which is a commercially available adsorbent for boron adsorption having substantially the same particle size Column adsorption / elution experiments were performed. The results are shown in FIGS. 2 and 3, respectively.

Example 5
In order to evaluate practicality, the influence on the adsorption performance of boron was examined from the number of times of reusing the column packed with the particulate cellulose-based adsorbent obtained in Example 1. In the same manner as in Example 4, adsorption / elution was repeated 8 times at a flow rate of SV = 50, and a column boron adsorption test was conducted. The results are shown in FIG.

  As shown in FIG. 4, the adsorption capacity of the column packed with the particulate cellulose-based adsorbent of the present invention does not decrease even after repeated regeneration in boron adsorption, and conversely, the adsorption capacity improves as the number of uses increases. It became clear to do. This is presumably because the epoxy functional group remaining in the glycidyl methacrylate (GMA) grafted sesulose particles reacts with the hydrochloric acid for boron recovery to convert the epoxy group into a diol. Since the conventional commercial product does not have an epoxy group, the particulate cellulose-based adsorbent of the present invention shows a great advantage compared to the commercial product in terms of excellent adsorption ability when repeatedly used.

Example 6
Using the particulate cellulose-based adsorbent obtained in Example 1, a germanium column adsorption experiment was conducted. First, the particulate cellulose adsorbent obtained in Example 1 was conditioned. The conditioned particulate cellulose-based adsorbent was packed in a slurry state into a column having an inner diameter of 16 mm and a height of 77.5 mm (bed volume: about 15 ml). Boron leakage curves were determined at pH 8.0.

  The column flow experiment was performed at room temperature using two kinds of flow rates (2.5 ml / min (SV = 10), 12.5 ml / min (SV = 50)) using a mini pump. As a sample solution, a 100 ppm boron phosphate buffer solution (pH 8.0) was used. The results are shown in FIG.

  As shown in FIG. 5, the particulate cellulose adsorbent of the present invention adsorbs better to germanium than boron under the same conditions. The BV value of the germanium fracture curve was 4-6 times that of boron.

Example 7
In order to examine the influence of the moisture content of the particulate cellulose-based adsorbent upon irradiation with the electron beam on the graft ratio, in the same manner as in Example 1 except that the particulate cellulose-based adsorbent having various moisture contents was used, Graft chains were introduced. As a result, when the moisture content was 0 to 10%, no change in the graft rate was observed. On the other hand, when the water content exceeded 10%, the graft ratio increased by 10 to 20%. The highest graft ratio was obtained when the water content was 20%.

  As described above, the particulate cellulose-based adsorbent according to the present invention is desired by efficiently polymerizing a reactive monomer without destroying the original structure and strength, using cellulose spherical particles having a high degree of crystallinity as a base material. This is a particulate cellulose-based adsorbent imparted with the above adsorption characteristics.

  Therefore, the particulate cellulose-based adsorbent according to the present invention has an excellent adsorbing ability for boron, germanium, arsenic and other semimetals, metals, etc., and is contaminated with these semimetals and metals. This is very advantageous when industrially purifying soil, seawater, factory wastewater, hot spring water, mine wastewater, etc., and separating, concentrating and recovering these semimetals and metals as beneficial resources. In addition, the particulate cellulose-based adsorbent of the present invention can adsorb and separate various amino acids, vitamins, proteins, nucleic acids, biopolymers such as sugars, etc. by appropriately selecting the ion exchange groups introduced. Can do. In particular, since cellulose is highly hydrophilic, it can be suitably used for the adsorption and separation of biopolymers.

  Furthermore, since the shape of the particulate cellulose-based adsorbent of the present invention has the same shape as conventional commercial ion exchange resin spheres / chelate resin spheres, the adsorption tower for ion exchange / chelate resin spheres, regeneration equipment, etc. are used as they are. can do. Therefore, it is considered that the particulate cellulose-based adsorbent according to the present invention can replace conventional chelate resin spheres in consideration of factors such as the manufacturing process, adsorption capacity, regeneration speed, and environmental aspect.

It is a figure which shows the result of having observed the particulate cellulose adsorbent obtained in the Example of this invention with the electron microscope, (A) is a figure which shows the whole particulate cellulose adsorbent, (B) Is a diagram showing the surface structure of the particulate cellulose-based adsorbent, (C) is a diagram showing a cross-sectional structure of the particulate cellulose-based adsorbent. It is a graph which shows the result of the column adsorption | suction experiment conducted about the particulate cellulose type adsorbent obtained in the Example of this invention, and the comparison control. It is a graph which shows the result of the column elution experiment performed about the particulate cellulose adsorbent obtained in the Example of this invention, and the comparison control. It is a graph which shows the result of having examined the influence on the adsorption | suction performance of boron from the reproduction | regeneration use frequency of the column filled with the particulate cellulose type adsorbent obtained in the Example of this invention. It is a graph which shows the result of the column adsorption | suction experiment conducted about the particulate cellulose type adsorbent obtained in the Example of this invention, and the comparison control.

Claims (18)

A particulate cellulose-based adsorbent in which a chelate-forming group and / or an ion-exchange group are introduced into a particulate cellulose-based substrate made of microcrystalline cellulose ,
The chelate-forming group and / or ion-exchange group is bonded to a graft chain introduced by graft polymerization of a hydrophobic monomer on the particulate cellulose base material,
A particulate cellulose-based adsorbent, wherein the graft chain has a graft ratio of 150 % or more.   The particulate cellulose-based adsorbent according to claim 1, wherein an average density of the chelate-forming groups and / or ion exchange groups is 1.0 mmol / g or more.   The particulate cellulose-based adsorbent according to claim 1 or 2, wherein the hydrophobic monomer is an epoxy group-containing ethylenically unsaturated monomer.   The particulate cellulose-based adsorbent according to claim 3, wherein the epoxy group remaining in the graft chain is dioled.   The particulate cellulose-based adsorbent according to any one of claims 1 to 4, wherein an average particle diameter is 100 to 1500 µm.   The chelate-forming group is a glucamine group, a diol group, a polyol group, an iminodiacetic acid group, a polyamine group, an amidoxime group, a dithiocarbamic acid group, a thiourea group, or an aminophosphate group. The particulate cellulose-based adsorbent according to any one of the above. A metalloid adsorbent comprising the particulate cellulose adsorbent according to any one of claims 1 to 6 . The metalloid adsorbent according to claim 7 , which is a boron adsorbent, a germanium adsorbent or an arsenic adsorbent. A method for producing a particulate cellulose-based adsorbent in which a chelate-forming group and / or an ion-exchange group are introduced into a particulate cellulose-based substrate made of microcrystalline cellulose ,
An activation step of activating a particulate cellulose-based substrate made of microcrystalline cellulose ;
A graft chain introducing step of introducing a graft chain by bringing the activated particulate cellulose base material into contact with an emulsion containing a hydrophobic monomer to graft polymerize the hydrophobic monomer to the particulate cellulose base material. When,
A functional group binding step of binding a chelate-forming group and / or an ion-exchange group to the introduced graft chain;
Including
The method for producing a particulate cellulose-based adsorbent, wherein the amount of the hydrophobic monomer contained in the emulsion is greater than 30% by weight and 80% by weight or less based on the total amount of the emulsion. The method for producing a particulate cellulose-based adsorbent according to claim 9 , wherein the emulsion further contains 3 to 10% by weight of a surfactant with respect to the hydrophobic monomer. The particulate cellulose-based adsorbent according to claim 9 or 10 , wherein in the activation step, a particulate cellulose-based substrate made of microcrystalline cellulose is irradiated with an ionizing radiation having a dose of 1 to 25 kGy. Manufacturing method. The method for producing a particulate cellulose-based adsorbent according to claim 11 , wherein the particulate cellulose-based substrate having a water content of more than 10% and 50% or less is irradiated with ionizing radiation. The method for producing a particulate cellulose-based adsorbent according to any one of claims 9 to 12 , wherein the emulsion is an aqueous emulsion. The method for producing a particulate cellulose-based adsorbent according to any one of claims 9 to 13 , wherein the hydrophobic monomer is an epoxy group-containing ethylenically unsaturated monomer. The method for producing a particulate cellulose-based adsorbent according to claim 14 , further comprising, after the functional group binding step, a step of diolizing an epoxy group remaining in the graft chain. The average particle diameter of the particulate cellulosic substrate, the manufacturing method of the particulate cellulosic adsorbing material according to any one of claims 9-15 which is a 30 to 800 m. The chelating group may, glucamine group, a diol group, a polyol group, iminodiacetic acid group, a polyamine group, an amidoxime group, dithiocarbamic acid group, thiourea group, or claims 9 to 16, characterized in that an amino phosphoric acid group The manufacturing method of the particulate cellulose adsorbent of any one of these. The ionizing radiation, gamma rays, electron beams, or the manufacturing method of the particulate cellulosic adsorbing material according to any one of claims 11 to 17, characterized in that an X-ray.