WO2022071243A1

WO2022071243A1 - Adsorbent

Info

Publication number: WO2022071243A1
Application number: PCT/JP2021/035441
Authority: WO
Inventors: 剛平山村; 竜馬宮本; 泉永野
Original assignee: 東レ株式会社
Priority date: 2020-09-30
Filing date: 2021-09-27
Publication date: 2022-04-07
Also published as: JPWO2022071243A1

Abstract

The present invention provides an adsorbent for which adsorption properties and recyclability of the absorbent are excellent, with respect to the recovery of valuable material and the removal of hazardous material in a water treatment process. This adsorbent includes: fibers having a diameter of 1-500μm; and metal particles which are supported by the fibers. The adsorbent contains 15-95 parts by mass of the metal particles per 100 parts by mass, and the size of crystallites of the metal particles is 1-30nm.

Description

Adsorbent

The present invention relates to an adsorbent having a function suitable for recovering valuable substances and removing harmful substances in a water treatment process.

In the treatment of wastewater containing metal ions, a water treatment process using an adsorbent has been proposed for the recovery of metals that are valuable as resources or the removal of metals that pollute the environment. In addition, when groundwater is used for industrial water and drinking water, an adsorbent is also used for the purpose of removing harmful substances.

Although the adsorbent is generally granular, fibrous adsorbents have been reported because they can be shaped, have excellent adsorptivity due to their high surface area, and have excellent low pressure loss. ..

For example, Patent Document 1 discloses an adsorbent that supports cerium hydroxide on hollow fibers made of polyvinylidene fluoride and is effective in removing boron from seawater. Further, Patent Document 2 describes fibrous adsorption effective for adsorbing and removing anions such as antimony and iodine in a liquid, in which a monomer having a cation exchange group is graft-polymerized on nylon fiber and then cerium-containing hydroxide is carried. The material is disclosed.

Japanese Patent Application Laid-Open No. 2010-227757 Japanese Patent Application Laid-Open No. 2018-158327

The adsorbent described in Patent Document 1 has the characteristics of removing turbidity and removing boron by adsorption, but has a problem of insufficient adsorptivity. Further, although the fibrous adsorbent described in Patent Document 2 has an adsorptive property of anions such as antimony, there is a problem that the reproducibility of the adsorbent is insufficient.

In view of the background of the prior art, it is an object of the present invention to provide an adsorbent which can be used for recovering valuable substances and removing harmful substances in a water treatment process and has excellent adsorptivity and reproducibility. ..

As a result of diligent studies to solve the above problems, the present inventors have found that a fibrous adsorbent in which metal particles having a specific range of crystallite size are supported on the fibers makes it possible to solve the above problems. , The present invention has been completed.

That is, the adsorbent of the present invention has any of the following configurations (1) to (7).
(1) An adsorbent having a fiber having a diameter of 1 to 500 μm and metal particles supported on the fiber, and the adsorbent contains 15 to 95 parts by mass of the metal particles per 100 parts by mass. However, the adsorbent is characterized in that the crystallite size of the metal particles is 1 to 30 nm.
(2) In the radial cross section of the fiber, the ratio of the amount of metal particles to the amount of fiber changes continuously in the radial direction, and the fiber at the position a at a depth of 0.1 μm from the outer surface to the inside of the fiber. The adsorption according to (1) above, wherein the ratio Ma of the amount of metal particles to the amount and the ratio Mb of the amount of metal particles to the amount of fibers at the center position b of the cross section satisfy 0.5 ≦ Mb / Ma ≦ 0.95. Material.
(3) The metal particles are particles containing at least one selected from the group consisting of sodium, magnesium, aluminum, calcium, titanium, manganese, iron, copper, zirconium, silver, lanthanum and cerium (1). Or the adsorbent according to (2).
(4) The metal particles contain cerium, and the weight ratio (Ce3: Ce4) of trivalent cerium Ce3 to tetravalent cerium Ce4 in the cerium is 20:80 to 1:99. ). The adsorbent according to any one of.
(5) The adsorbent according to any one of (1) to (4) above, wherein the fiber is a porous fiber.
(6) The adsorbent according to (5) above, wherein the porous fiber is a hollow fiber.
(7) The adsorbent according to (6) above, wherein the hollow fiber has a uniform pore structure from the outer surface to the inner surface.

According to the present invention, there is provided an adsorbent having excellent adsorptivity and reproducibility of the adsorbent in recovering valuable substances and removing harmful substances in a water treatment process.
Specifically, it can be preferably used for recovery of rare metals such as chromium, nickel, cobalt and antimony contained in factory wastewater, removal of arsenic and fluorine contained in groundwater, and removal of boron contained in seawater.

FIG. 1 is a cross-sectional view of a fibrous adsorbent according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a hollow thread-shaped adsorbent, which is another embodiment of the present invention. FIG. 3 is a partial cross-sectional view in the radial direction of the adsorbent for explaining a visual field in measuring the ratio of the amount of metal particles to the amount of fibers. FIG. 4 is a partial cross-sectional view in the radial direction of the adsorbent for explaining the visual field in the measurement of the ratio Ma of the amount of metal particles. FIG. 5 is a partial cross-sectional view in the radial direction of the adsorbent for explaining the visual field in the measurement of the ratio Mb of the amount of metal particles.

Hereinafter, the adsorbent of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.
In the present invention, the "fibrous" means a shape that is long in one direction, and the ratio (aspect ratio) of the length in the longitudinal direction to the length in the lateral direction is 2 or more.
Further, in the present specification, "mass" is synonymous with "weight".

The adsorbent of the present invention has fibers having a diameter of 1 to 500 μm and metal particles supported on the fibers.

(1) Fiber (1-1) Material The material constituting the fiber of the adsorbent of the present invention is not particularly limited, and for example, polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polytetrafluoroethylene (PTFE), and polyfluoride. Halogenated polyolefins such as vinylidene, polyvinyl compounds such as polyacrylonitrile, polyamides such as nylon 6, nylon 66, nylon 11, nylon 6-66 copolymers, polyethylene terephthalates, polyesters such as polylactic acid, polycarbonates, poly (meth) acrylates. , Polysulfone, polyethersulfone, polyphenylene sulfide, cellulose ester and the like. The fiber is mainly composed of at least one material selected from the group consisting of these. Here, the "main component" means that the content is 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more. Among these, polyamides, polyesters, and cellulose esters, which are hydrophilic polymers, are preferable in that the content of metal particles in the radial cross section of the fiber is within the scope of the present invention.

Further, these materials may be a combination of two or more kinds, or may contain additives other than those exemplified above. Additives here are other polymers, plasticizers, antioxidants, organic lubricants, crystal nucleating agents, organic particles, inorganic particles, end-blocking agents, chain extenders, UV absorbers, infrared absorbers, anti-coloring agents. Examples thereof include agents, antibacterial agents, antistatic agents, deodorants, flame retardants, weather resistant agents, antistatic agents, antioxidants, ion exchangers, defoaming agents, coloring pigments, photocatalysts and the like.

(1-2) Shape The cross-sectional shape of the fiber is not particularly limited, and may be, for example, a circular shape, a multi-leaf shape, a flat shape, an elliptical shape, or the like, a cruciform shape, a sharp (#) shape, a hollow shape, or a combination thereof. It may have a modified cross section such as a shape. Further, the fiber may be a composite fiber such as a core sheath type or a side-by-side type.

The fiber contained in the adsorbent of the present invention is preferably a porous fiber because it has a large surface area and high adsorptivity. The pore structure of the porous fiber is not limited to a specific shape. Examples of the method for producing the porous fiber include a non-solvent phase separation method, a heat-induced phase separation method, a stretch cleavage method, a plasticizer extraction method, or a method in which two or more of these methods are combined.

Since the treated raw water easily comes into contact with the adsorption site of the porous portion, the porous fiber preferably has a hollow portion penetrating in the longitudinal direction. A fiber having such a hollow portion is hereinafter referred to as a "hollow fiber". When the porous fiber is a hollow fiber, the shape and number of the hollow portion in the radial (short direction) cross section of the fiber are not particularly limited.

The hollow fiber preferably has a uniform pore structure from the outer surface to the inner surface in order to achieve both the ability to remove turbidity, bacteria, viruses, etc. by the membrane and the adsorptivity by the adsorption site of the porous part. The uniform hole structure referred to here means that in the radial cross section of the hollow fiber, the difference between adjacent parts is within ± 30% with respect to the average hole diameter in each part obtained by dividing the outer surface to the inner surface into 10 equal parts. say.

The average pore size in the porous structure is preferably 10 to 500 nm, more preferably 50 to 500 nm, in order to sufficiently exhibit the adsorptivity of the porous portion due to the adsorption site. If the adsorbent is a hollow fiber and its diameter is an appropriate size, the average pore diameter r (nm) in the hollow fiber can be obtained by using the bubble point method. Air pressure is gradually applied from one side of the hollow yarn in water, the pressure at which air leaks continuously for the first time is recorded as the bubble point Pb (kPa), and the surface tension γ (N / m) of the measured liquid is used. The average pore diameter is calculated by the following formula {1}.
r (nm) = 4000 × γ (N / m) / Pb (kPa) ・・・ Equation {1}

The adsorbent of the present invention may be a single fiber or a multifilament containing a plurality of single fibers. Further, the adsorbent may be a non-woven fabric, and the basis weight of the non-woven fabric is preferably 1 to 10 g / m ² from the viewpoint of adsorptivity and reproducibility.

The diameter of the fiber is preferably 1 to 500 μm. The diameter here is the diameter of a single fiber. When the fiber is hollow, the diameter here means the outer diameter of the fiber. If the diameter of the fiber is less than 1 μm, the tensile strength of the fiber is insufficient, which causes a problem in handleability. If the diameter of the fiber exceeds 500 μm, the adsorptivity and the reproducibility of the adsorbent are insufficient. The diameter of the fiber is preferably 5 μm or more, and more preferably 10 μm or more. The diameter of the fiber is preferably 450 μm or less, more preferably 400 μm or less.

(2) Metal particles (2-1) Type The adsorbent of the present invention is one in which metal particles are supported on fibers. The type of metal particles is not particularly limited, and may be particles containing at least one selected from the group consisting of sodium, magnesium, aluminum, calcium, titanium, manganese, iron, copper, zirconium, silver, lanthanum and cerium. preferable. These can be arbitrarily selected depending on the adsorption target.

As the metal particles, metal hydroxides, metal hydrous oxides, and metal hydrated oxides are preferable from the viewpoint of adsorption capacity.

The type of metal particles can be determined by SEM-EDX analysis or the like. Information on the valence of the metal and the structure around the metal element can be obtained by XPS analysis or X-ray absorption fine structure (XAFS) analysis.

When the metal particles are particles containing cerium, the weight ratio (Ce3: Ce4) of trivalent cerium Ce3 and tetravalent cerium Ce4 is preferably 20:80 to 1:99. Ce3: Ce4 is more preferably 10:90 to 1:99, and even more preferably 5:95 to 1:99.

(2-2) Particle diameter The particle diameter of the metal particles supported on the fiber is preferably 1 to 1000 nm. The particle size referred to in the present invention means the particle size in a dispersed state (primary particles) if each particle is dispersed, and if the particles are aggregated, the particles are aggregated. It refers to the particle size of the state (secondary particles).

The particle size of the metal particles is more preferably 500 nm or less, further preferably 100 nm or less, and particularly preferably 50 nm or less. When the particle size exceeds 1000 nm, the number of adsorption sites existing on the outer surface of the particles is reduced, and sufficient adsorption cannot be exhibited. Considering the aggregation of particles during the production of the adsorbent, the lower limit of the particle size is 1 nm.

(2-3) Crystallite size The crystallite size of the metal particles supported on the fiber is 1 to 30 nm. The crystallite size refers to the crystallite size calculated using Scherrer's equation from the half width of the peak of the 2θ-θ intensity data obtained by wide-angle X-ray scattering measurement.

The smaller the crystallite size of the metal particles is, the more preferable it is, but with the current technology, it is considered that the lower limit is about 1 nm. When the crystallite size of the metal particles is 30 nm or less, good adsorptivity and reproducibility of the adsorbent can be obtained. Although the reason for this is not clear, it is considered that when the crystallite size is 30 nm or less, the integrity of the crystal does not become too high, and the substance to be adsorbed and the chemicals at the time of regeneration easily permeate the metal particles. The crystallite size of the metal particles is preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 6 nm or less. The crystallite size of the metal particles is preferably 2 nm or more, more preferably 3 nm or more.

(2-4) Content of Metal Particles The content of metal particles in the adsorbent of the present invention is 15 when the entire adsorbent is 100 parts by mass from the viewpoint of achieving both adsorptivity and tensile strength of fibers. It is important that it is up to 95 parts by mass. If the content of the metal particles is less than 15 parts by mass, the adsorptivity may be insufficient. If the content of the metal particles exceeds 95 parts by mass, the tensile strength of the fiber is insufficient, which may cause a problem in handleability. The content of the metal particles is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more. The content of the metal particles is preferably 85 parts by mass or less, more preferably 75 parts by mass or less. When two or more types of metal particles are contained, the total content thereof is used for judgment.

The content of the metal particles is determined by heating the adsorbent using a thermal weight measuring device or an electric furnace and burning off the components other than the metal particles to take out the metal particles, and the mass (W1) of the adsorbent before heating. It is calculated as (W2 / W1) × 100 (parts by mass) from the mass (W2) of the taken out metal particles.

(2-5) Metal particles in the radial cross section In the radial cross section of the fiber, it is preferable that the ratio of the metal particle amount to the fiber amount continuously changes in the radial direction. The ratio of the amount of metal particles to the amount of fibers referred to here is the content of metal elements derived from metal particles measured by SEM-EDX analysis in the radial cross section, which is one type unique to fibers derived from fibers. Calculated by dividing by the element content. When two or more kinds of metal particles are contained, the total amount of metal particles thereof is used.

Further, the continuous change here means that in the radial cross section, the difference between the adjacent parts is the ratio of the amount of metal particles to the amount of fiber in each part divided into 10 equal parts from the outer surface of the fiber to the center of the cross section. It is within ± 10%. The center of the cross section here means the center of gravity when the cross section is viewed as a figure. When the shape of the radial cross section is hollow, the determination is made at each portion obtained by dividing the outer surface to the inner surface into 10 equal parts.

For the radial cross section of the adsorbent, for example, a method of freezing the adsorbent with liquid nitrogen and then splitting it by applying stress with a razor or a microtome, or a method of preparing a cross section with a broad argon ion beam after embedding in a resin. It is obtained by such as.

In the radial cross section of the adsorbent, the ratio Ma of the amount of metal particles to the amount of fibers at the position a at a depth of 0.1 μm from the outer surface to the inside, and the amount of metal particles to the amount of fibers at the center position b of the adsorbent in the cross section. It is preferable that the ratio Mb of is satisfied with 0.5 ≦ Mb / Ma ≦ 0.95. When Mb / Ma is 0.5 or more, good adsorptivity can be obtained, and when Mb / Ma is 0.95 or less, good reproducibility of the adsorbent can be obtained. When the adsorbent contains two or more kinds of metal particles, Ma and Mb are the total amount of the metal particles.

As shown in FIG. 1, in the fibrous adsorbent 1 having a clogged structure inside, the center position b of the cross section means the center of gravity of the cross section. Further, as shown in FIG. 2, in the fibrous adsorbent 7 which is a hollow fiber, the center position b in the cross section means a position equidistant from the outer surface 3 and the inner surface 5.

By satisfying the range described in (2-4) above and the range of Mb / Ma of 0.5 or more and 0.95 or less, the content of the metal particles is more excellent in adsorptivity, reproducibility, and fiber. Can develop the tensile strength of. For example, such a fibrous adsorbent can be regenerated even when the liquid passing speed of the drug during regeneration is as high as 30 h ^-1 or more in terms of space velocity SV value.

Ma is calculated by dividing the content of metal elements derived from metal particles at position a by the content of one fiber-specific element derived from fibers at position a, as measured by SEM-EDX analysis. do. Mb is also calculated in the same manner at the position b. This index is preferably 0.55 ≦ Mb / Ma ≦ 0.95, more preferably 0.6 ≦ Mb / Ma ≦ 0.9, and 0.65 ≦ Mb / Ma ≦ 0.9. Is particularly preferable.

(3) Use of adsorbent The adsorbent of the present invention can be used in an industrial water treatment process for the purpose of recovering valuable substances and removal of harmful substances, and for a water purifier for the purpose of removing harmful substances. ..

The form when the adsorbent of the present invention is used is not particularly limited. The adsorbent may be packed in a container that can absorb and pass water in the form of cotton, cut fiber, etc., or in the form of filament, non-woven fabric, woven fabric, knitted fabric, etc., wrapped around a central pipe with a hole, and further. It may be packed in a container that can pass water by radial flow. When the adsorbent is a hollow fiber, the end of the opening of the hollow fiber is hardened with a potting agent, and raw water can permeate from the outer surface to the inner surface of the hollow fiber or vice versa. It may be used in the form of a hollow fiber membrane module.

(4) Manufacturing method (4-1) Fiber manufacturing method The fiber manufacturing method used for the adsorbent of the present invention is not particularly limited, and in addition to the conventional melt spinning, dry spinning, and wet spinning, electrospinning and the like are adopted. can. When the fiber is a porous fiber, the production method is not particularly limited, and a non-solvent phase separation method, a heat-induced phase separation method, a stretch cleavage method, a plasticizer extraction method and the like can be adopted.

(4-2) Method of Supporting Metal Particles on Fibers In the adsorbent of the present invention, the method of supporting metal particles on fibers is not particularly limited. For example, it may be supported by interaction with the functional group of the polymer constituting the fiber, or it may be physically supported on the fine irregularities on the surface of the fiber or the fine pores in the porous fiber, or the fiber may be supported. It may be supported in the gaps of the microstructure such as the branched polymer or the graft chain, or it may be supported by a method of mixing metal particles with the polymer constituting the fiber and then spinning, or it may be supported by a method of combining these. You may.

Next, the method of supporting the metal particles on the fiber will be specifically described by taking the case of supporting the hydrated cerium oxide particles on the nylon 6 fiber as an example, but the method for producing the adsorbent is limited to this method. is not.

Nylon 6 fibers, methacrylic acid and acrylic acid, which are monomers, are added to distilled water to which a radical initiator, a reducing agent and a chelating agent have been added so as to have a predetermined bath ratio and concentration, and the first stage graft polymerization is performed. .. Here, the amount of the monomer is 1 to 10 parts by mass with respect to 100 parts by mass of the fiber, and the reaction time is 60 minutes or more. Subsequently, the fibers that have undergone the first-stage graft polymerization are used to perform the second-stage graft polymerization in the same manner as in the first stage. Here, the amount of the monomer is 50 to 500 parts by mass and the reaction time is 5 to 20 minutes with respect to 100 parts by mass of the fiber before the polymerization in the first stage.

By immersing the fibers that have undergone two-step graft polymerization in an aqueous solution of sodium hydroxide and washing with distilled water, the graft-polymerized methacrylic acid and acrylic acid are converted into sodium methacrylate and sodium acrylate, respectively. Then, the sodium is exchanged for cerium by immersing it in an aqueous solution of a trivalent cerium salt such as cerium nitrate, and then the fiber is supported by hydrated cerium oxide particles by being added to a basic aqueous solution and precipitated. Obtain a state adsorbent.

One of the effective methods for setting the content of metal particles in the radial cross section of the fibrous adsorbent within the preferable range of the present invention is to carry out two-step graft polymerization using a radical initiator as described above to obtain a metal. This is a method of introducing a functional group that can be adsorbed and carried by particles. Further, the amount of the monomer and the reaction time for the fiber before polymerization should be the same as described above, the amount of the monomer in the second stage should be 10 to 100 times that of the first stage, and the reaction time in the second stage should be the first. It is more effective to set the stage to 1/3 to 1/20. For example, in the radiation graft polymerization method not adopted in the present invention, the graft ratio as a bulk can be controlled, but the graft ratio cannot be controlled at each part of the radial cross section of the fiber, so that the metal particles in the radial cross section cannot be controlled. It is also difficult to control the content of.

One of the effective methods for setting the crystallite size of the metal particles carried on the fiber within the scope of the present invention is to make the metal ion bonded to the carboxy group such as methacrylic acid or acrylic acid basic as described above. This is a method of precipitating in addition to the aqueous solution of. At this time, the type of the basic aqueous solution is not particularly limited, but it is more effective to use a divalent base such as calcium hydroxide than a monovalent base such as sodium hydroxide in terms of reducing the crystallite size. I found that there is.

Further, when the metal particles are particles containing cerium and Ce3: Ce4 is within the preferable range of the present invention, one of the effective methods is to precipitate metal ions bonded to the functional group of the fiber. , A method of reacting with a divalent base such as calcium hydroxide for 12 hours or more.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited by this.

[Measurement and evaluation method]
Each characteristic value in the example was obtained by the following method.

(1) Fiber diameter The adsorbent was frozen in liquid nitrogen as needed, and then split by applying stress so that a cross section in the direction perpendicular to the longitudinal direction of the fiber appeared. The cross sections of any of the 10 fibers thus prepared were observed with an optical microscope, and the average value thereof was calculated as the fiber diameter (μm).

(2) Content of metal particles First, the mass (W1) of the adsorbent was weighed. Next, the adsorbent was heated to 600 ° C. or higher by a thermal weight measuring device or an electric furnace to burn off components other than the metal particles, so that the metal particles were taken out and the mass (W2) of the metal particles was weighed. The content of the metal particles was calculated as (W2 / W1) × 100 (parts by mass).

(3) Ratio of the amount of metal particles to the amount of fibers in the radial cross section A cross section was prepared so that the direction perpendicular to the longitudinal direction of the adsorbent and the radial cross section of the fibers appeared. The cross section was prepared by freezing it in liquid nitrogen and then cutting it by applying stress with a razor.

Next, the obtained cross section was adjusted to have an energy of about 2 to 3 times the target peak by using a field emission scanning electron microscope (FE-SEM) Merlin and Bruker AXS EDS detector XFlash6. , SEM-EDX analysis was performed. Specifically, as shown in FIG. 3, in the cross section, from an arbitrary position on the outer surface 3 to the center position b of the cross section is divided into 10 regions S1, S2 ... S10 having the same thickness. In each region, three 0.1 μm square fields (indicated by the dotted line in the figure) are arbitrarily selected, and in each field, the content (% by mass) Mq of the metal element derived from the metal particles and the fiber are derived. The content (mass%) Fq of one kind of element peculiar to the fiber such as carbon was measured. Mq / Fq was calculated for each visual field, and the average value of three Mq / Fq in the same region was calculated as the ratio of the amount of metal particles to the amount of fiber in each region.
An average value was further calculated from the ratio of the amount of metal particles to the amount of fibers in each of the regions S1 to S10 thus obtained, and this was used as the ratio of the amount of metal particles to the amount of fibers.

When the adsorbent is a hollow fiber, the outer surface to the inner surface is divided into 10 equal parts, the ratio of the metal particle amount to the fiber amount is obtained in each region, and the average value is the metal particle amount to the fiber amount. The ratio was used.

Regarding the ratio of the amount of metal particles to the amount of fibers in each region S1 to S10, if the difference between adjacent portions is within ± 10%, the ratio of the amount of metal particles to the amount of fibers in the radial cross section changes continuously in the radial direction. I said that.

(4) Ratio of amount of metal particles Ma, Mb
SEM-EDX analysis was performed in the same manner as in (3) above. Specifically, in the cross section, as shown in FIG. 4, a 0.1 μm square field of view centered on any three positions a having a depth of 0.1 μm from the outer surface 3 toward the inside (dotted line in the figure). (Indicated by) was selected. In each field of view, a ratio was obtained by dividing by the total value (mass%) of the content of the metal element and the content (mass%) of any one kind of non-metal element. The average value of the obtained three ratios was taken as the ratio Ma of the amount of metal particles.

Similarly, as shown in FIG. 5, any three fields of view 0.1 μm square (dotted line in the figure) in a circle with a diameter of 0.3 μm (indicated by a dotted chain line) centered on the center position b of the cross section. (Indicated by) was selected. The content (% by mass) of the metal element derived from the metal particles in each field of view is the content (mass%) of the element contained in the fiber and not contained in the metal particles (the same element used for calculating the ratio Ma). ) Was taken as the ratio Mb of the amount of metal particles. In this way, by standardizing the amount of metal atoms using the amount of any one non-metal element, that is, the element contained only in the fiber and not contained in the metal particles, the abundance is determined by the position in the adsorbent. I made it possible to compare.

When the adsorbent was a hollow fiber, the position equidistant from the outer surface and the inner surface was measured as the center position b of the cross section.

(5) Adsorbability (5-1) Adsorption property of fibrous adsorbent or sheet-shaped adsorbent When the fibrous adsorbent cut to a length of 5 to 10 mm or the adsorbent is sheet-like like a non-woven fabric. Was immersed in pure water with an adsorbent cut into pieces of about 5 mm square. A cylindrical column (inner diameter 16 mm, length 50 mm, internal volume 10.0 mL) to which filters and joints can be attached to the upper and lower parts was filled with an adsorbent in water to prepare an evaluation column.
Sodium arsenite was dissolved in distilled water to prepare raw water for evaluation prepared so that the trivalent arsenic concentration was 100 ppb.

The tube connected to the peristaltic pump and the evaluation column were connected, the space velocity SV value with respect to the internal volume of the column was adjusted to be 75h ^-1 , and the raw water was started to flow.

10 mL of the permeate was collected every 500 BV (5 L) of the bed volume (BV) value with respect to the internal volume of the column. The arsenic concentration in the permeate was measured by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy), and the removal rate was calculated by the following formula.
Removal rate (%) = (concentration of raw water-concentration of permeate) / concentration of raw water x 100
The life of the adsorbent was defined as the BV immediately before the removal rate was less than 90%.

(5-2) Adsorbability in Hollow Fiber Adsorbent When the adsorbent is a hollow fiber, a hollow fiber membrane module was prepared as follows and the adsorptivity was evaluated.
A hollow fiber bundle consisting of multiple hollow fibers is inserted into a cylindrical column to which joints can be attached to the upper and lower parts in a half-length bent state, and the end on the hollow fiber opening side is an epoxy potting agent. Hardened with. Joints with liquid inlets and outlets were attached to the upper and lower parts of the column, and an evaluation column was prepared so that raw water could permeate from the outside to the inside of the hollow fiber.
Sodium arsenite was dissolved in distilled water to prepare raw water for evaluation prepared so that the trivalent arsenic concentration was 100 ppb.

The tube connected to the peristaltic pump and the evaluation column were connected, the space velocity SV value with respect to the adsorbent volume was adjusted to be 75h ^-1 , and the raw water was started to flow. Here, the adsorbent volume is a volume obtained by the following formula from the outer diameter and inner diameter of the hollow fiber that has been immersed in water and made wet, the length of the hollow fiber, and the number of hollow fibers.
Adsorbent volume = ((outer diameter) ^2- (inner diameter) ² ) x length x number / 4

10 mL of the permeate was collected every 500 BV of the bed volume (BV) value with respect to the adsorbent volume. The arsenic concentration in the permeate was measured by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy), and the removal rate was calculated by the following formula.
Removal rate (%) = (concentration of raw water-concentration of permeate) / concentration of raw water x 100
The life of the adsorbent was defined as the BV immediately before the removal rate was less than 90%.

(6) Reproductive property The adsorbent was regenerated by passing a liquid through the evaluation column whose removal rate was less than 90% in (5) above under the following conditions. First, pure water is 10 BV at a rate of SV30h ^-1 , then a 2N sodium hydroxide aqueous solution is 10 BV at a rate of SV30h ^-1 , and then pure water is at a rate of SV30h ^-1 and the pH of the permeate is 6.5. The liquid was passed until it was in the range of ~ 7.5.

Using the adsorbent material regenerated in this way, the adsorptivity was evaluated by the method described in (5), and the reproducibility calculated by the following equation was used for evaluation according to the following criteria A to D. Of the following criteria, "A", "B" and "C" are "OK" and "D" is not.
Reproducibility (%) = Adsorbent life after regeneration (BV) / Adsorbent life before regeneration (BV) x 100
A: Reproductive property is 90% or more B: Reproductive property is 80% or more and less than 90% C: Reproductive property is 70% or more and less than 80% D: Reproductive property is less than 70%

(7) Crystallet size of metal particles The adsorbent was fixed to the sample holder, and synchrotron radiation wide-angle X-ray scattering measurement was performed under the following measurement conditions.
As a synchrotron radiation facility, Spring-8 BL03XU (X-ray wavelength λ: 0.10 nm, beam diameter: length 0.1 mm, width 0.2 mm, measurement time: 60 seconds, wide-angle camera length: about 70,100 mm, wide-angle detector The crystallite size was calculated using the Scherrer's formula from the half width β (rad) of the peak of the 2θ-θ intensity data obtained using (SOPHIAS, pixel size: 30 μm square). Here, K is a Scherrer constant (= 0.9).
L = Kλ / (βcosθ)

(8) Ratio of trivalent cerium component Ce3 and tetravalent cerium component Ce4 (Ce3: Ce4)
By irradiating the adsorbent with X-rays and measuring the amount of absorption thereof, the X-ray absorption fine structure (XAFS, X-ray Absorption Fine Structure) spectrum was measured under the following measurement conditions.
As an experimental facility, the experimental station BL11S2 (spectrometer: Si (111) 2 crystal spectroscope, absorption edge: Ce L ₃ (5723eV) absorption edge, detection method: transmission method, detector: Aichi Synchrotron Optical Center (AichiSR)): In the Ce L ₃ -end XANES spectrum obtained using the ion chamber), a mixed component was assumed and component analysis was performed by performing linear fitting using the reference spectrum. The reference spectrum may be selected according to the structure of cerium in the adsorbent. For example, when the trivalent cerium component is bonded to a carboxy group such as methacrylic acid or acrylic acid, Ce (CH ₃ COO) ₃・ H ₂ O may be used, and CeO ₂ · nH ₂ O may be used as the tetravalent cerium component.

[Manufacturing of fibrous adsorbent]
(Example 1)
20 g of nylon 6 fibers (235 decitex, 34 filaments, single fiber diameter 28 μm) cut to a length of about 5 cm were added to an aqueous sodium carbonate solution (0.2 g / L) at a bath ratio of 50, and after stirring at room temperature for 30 minutes, It was washed with pure water. Distilled water was prepared so that the nylon 6 fibers refined in this way had a bath ratio of 50, and 0.75 g of methacrylic acid, 0.25 g of acrylic acid, 1.5 g of sodium hydroxymethanesulfinate dihydrate, and ethylenediamine tetraacetic acid. 0.5 g of disodium dihydrate and 0.5 g of ammonium persulfate were added, and the mixture was stirred and dissolved. The refined nylon 6 fiber was added thereto, and the mixture was stirred at 70 ° C. for 60 minutes and then washed with pure water to obtain a fiber that had undergone the first-stage graft polymerization.

Distilled water was prepared so that the fibers had a bath ratio of 50, and 37.5 g of methacrylic acid, 12.5 g of acrylic acid, 1.5 g of sodium hydroxymethanesulfinate dihydrate, and disodium dihydrate tetraacetate dihydrate dihydrate were prepared. 0.5 g and 0.5 g of ammonium persulfate were added, and the mixture was stirred and dissolved. Fibers that had undergone the first-stage graft polymerization were added thereto, and the mixture was stirred at 70 ° C. for 15 minutes and then washed with pure water to obtain fibers that had undergone the second-stage graft polymerization.

This fiber was added to a 1N aqueous sodium hydroxide solution at a bath ratio of 100, stirred at room temperature for 1 hour, and then washed with pure water. Subsequently, this fiber was added to a 0.2 M aqueous solution of cerium nitrate hexahydrate at a bath ratio of 100, stirred at room temperature for 1 hour, then added to a 0.1 N sodium hydroxide aqueous solution at a bath ratio of 100, and stirred at room temperature for 1 hour. , Washed with pure water and vacuum dried at 40 ° C. for 15 hours to obtain the desired fibrous adsorbent.

The obtained adsorbent was supported on cerium hydrated hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 2)
The target adsorbent was obtained by the same procedure as in Example 1 except that the time for graft polymerization in the second stage was set to 5 minutes.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 3)
18 parts by mass of nylon 6 (Toray Industries, Inc. "Amilan"), 22 parts by mass of sulfolane, and 60 parts by mass of dimethyl sulfone were dissolved at 180 ° C. This solution was discharged from the outside of the double tube type mouthpiece, and at the same time, glycerin was discharged from the inside of the double tube type mouthpiece. The discharged solution was solidified in a 50 mass% glycerin aqueous solution and wound up. The obtained hollow fiber was immersed in pure water for 15 hours to extract the solvent, and then vacuum dried at 40 ° C. for 15 hours to obtain a nylon 6 hollow fiber membrane. The obtained hollow fiber membrane had a uniform pore structure from the outer surface to the inner surface, and the average pore diameter thereof was 185 nm.

Distilled water was prepared so that 20 g of nylon hollow fiber membrane bundles cut to a length of about 30 cm had a bath ratio of 50, and 0.75 g of acetic acid, 0.25 g of acrylic acid, and sodium hydroxymethanesulfate dihydrate 1. 5 g, 0.5 g of disodium disodium tetraacetate dihydrate and 0.5 g of ammonium persulfate were added, and the mixture was stirred and dissolved. A hollow fiber membrane was added thereto, and the mixture was stirred at 70 ° C. for 60 minutes and then washed with pure water to obtain a hollow fiber membrane that had undergone the first-stage graft polymerization.

Distilled water was prepared so that the hollow fiber membrane had a bath ratio of 50, and 37.5 g of methacrylic acid, 12.5 g of acrylic acid, 1.5 g of sodium hydroxymethanesulfinate dihydrate, and disodium disodium tetraacetate of ethylenediamine were prepared. 0.5 g of Japanese product and 0.5 g of ammonium persulfate were added, and the mixture was stirred and dissolved. A hollow fiber membrane that had undergone the first-stage graft polymerization was added thereto, and the mixture was stirred at 70 ° C. for 15 minutes and then washed with pure water to obtain a hollow fiber membrane that had undergone the second-stage graft polymerization.

This hollow fiber membrane was added to a 1N aqueous sodium hydroxide solution at a bath ratio of 100, stirred at room temperature for 1 hour, and then washed with pure water. Subsequently, this hollow fiber membrane was added to a 0.2 M aqueous solution of cerium nitrate hexahydrate at a bath ratio of 100, stirred at room temperature for 1 hour, then added to a 0.1 N sodium hydroxide aqueous solution at a bath ratio of 100, and at room temperature for 1 hour. After stirring, the mixture was washed with pure water and vacuum dried at 40 ° C. for 15 hours to obtain the desired adsorbent.

(Example 4)
The target adsorbent was obtained by the same procedure as in Example 3 except that the time for graft polymerization in the second stage was set to 5 minutes.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 5)
An adsorbent was obtained by the same procedure as in Example 1 except that the second step of graft polymerization was not performed.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 6)
Except that the methacrylic acid at the time of the first stage graft polymerization was 37.5 g, the acrylic acid was 12.5 g, the stirring time at 70 ° C., which was the graft polymerization time, was 15 minutes, and the second stage graft polymerization was not performed. Obtained an adsorbent by the same procedure as in Example 1.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 7)
Except for the fact that methacrylic acid was 37.5 g and acrylic acid was 12.5 g during the first-stage graft polymerization, the stirring time at 70 ° C., which was the graft polymerization time, was 60 minutes, and the second-stage graft polymerization was not performed. Obtained an adsorbent by the same procedure as in Example 1.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 8)
At the stage of precipitating cerium hydrate hydrate in addition to the basic aqueous solution, add it to a 0.1N sodium hydroxide aqueous solution at a bath ratio of 100 and stir at room temperature for 1 hour to make a 0.02M calcium hydroxide aqueous solution. The target adsorbent was obtained by the same procedure as in Example 1 except that the mixture was added at a bath ratio of 100 and stirred at room temperature for 12 hours.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 1 shows other structures and performances.

(Example 9)
The target adsorbent was obtained by the same procedure as in Example 8 except that the time for graft polymerization in the second stage was set to 5 minutes.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Example 10)
At the stage of precipitating cerium hydrate hydrate in addition to the basic aqueous solution, add it to a 0.1N sodium hydroxide aqueous solution at a bath ratio of 100 and stir at room temperature for 1 hour to make a 0.02M calcium hydroxide aqueous solution. The target adsorbent was obtained by the same procedure as in Example 3 except that the mixture was added at a bath ratio of 100 and stirred at room temperature for 12 hours.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Example 11)
The target adsorbent was obtained by the same procedure as in Example 10 except that the time for graft polymerization in the second stage was set to 5 minutes.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Example 12)
In the step of precipitating cerium hydrate hydrate in addition to the basic aqueous solution, the procedure was the same as in Example 1 except that the aqueous solution was changed to a 0.1N sodium hydroxide aqueous solution to make a 0.1N potassium hydroxide aqueous solution. The desired adsorbent was obtained.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Example 13)
At the stage of precipitating cerium hydrate in addition to the basic aqueous solution, the procedure was the same as in Example 1 except that the solution was changed to a 0.1N sodium hydroxide aqueous solution to a 0.5N potassium hydroxide aqueous solution. The desired adsorbent was obtained.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Example 14)
45 parts by mass of cellulose acetate propionate having a weight average molecular weight of 178,000 and average substitutions of acetyl and propionyl groups of 1.9 and 0.7, respectively, and 25 parts by mass of polyethylene glycol having a molecular weight of 600, PVP / acetic acid. 30 parts by mass of a vinyl copolymer (Kollidon VA 64 (BASF Japan Co., Ltd.) was melt-kneaded at 220 ° C. using a twin-screw extruder, homogenized, and then introduced into a melt-spun pack having a spinning temperature of 220 ° C. It was spun below the outside of the double circular tube type mouthpiece hole, wound up with a winder, and then immersed in a 50% ethanol aqueous solution for 12 hours to elute polyethylene glycol and PVP / vinyl acetate copolymer. The hollow filament film obtained had a uniform pore structure from the outer surface to the inner surface, and the average pore diameter thereof was 127 nm.

The hollow fiber membranes were cut to a length of about 30 cm, arranged, and subjected to corona discharge treatment on both sides with a surface treatment strength of 30 W / min / m ² under a nitrogen atmosphere. The obtained hollow fiber membrane was immersed in a dispersion liquid "Zirconeo" of zirconia nanoparticles (manufactured by Aitec Co., Ltd., solvent: water, concentration: 3% by mass, particle diameter ≤ 10 nm) for 1 day at room temperature. Then, the target adsorbent was obtained by washing with water to remove excess particles and vacuum drying at 40 ° C. for 15 hours.

Zirconia was supported on the obtained adsorbent, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of zirconium by the content of carbon. Table 2 shows other structures and performances.

(Example 15)
The purpose was to follow the same procedure as in Example 14 except that a dispersion of titanium oxide (manufactured by Sigma-Aldrich, solvent: water, concentration: 40% by mass, primary particle diameter ≤ 21 nm) was used as the particle dispersion. Adsorbent was obtained.
Titanium oxide was supported on the obtained adsorbent, and the ratio of the amount of metal particles to the amount of fibers changed continuously in the radial direction in the radial cross section of the fibers. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of titanium by the content of carbon. Table 2 shows other structures and performances.

(Comparative Example 1)
Hydrated cerium oxide prepared by gradually adding 1 L of 0.2N sodium hydroxide aqueous solution to 1 L of 0.05 M cerium nitrate hexahydrate aqueous solution as a dispersion of particles and stirring at room temperature for 1 hour. The target adsorbent was obtained by the same procedure as in Example 14 except that the dispersion liquid of the particles was used.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 2 shows other structures and performances.

(Comparative Example 2)
20 g of nylon 6 fibers (28 filaments, single fiber diameter 40 μm) cut to a length of about 5 cm are added to an aqueous sodium carbonate solution (0.2 g / L) at a bath ratio of 50, stirred at room temperature for 30 minutes, and then with pure water. Washed. Nylon 6 fibers refined in this way were placed in a polyethylene bag, the inside of the bag was replaced with nitrogen, the bag was placed in a foamed styrene box together with 500 g of dry ice, irradiated with gamma rays of 50 kGy, and then the fibers were placed in a glass ampoule. A 10% by mass methanol solution of glycidyl methacrylate was introduced therein, and graft polymerization was carried out at 40 ° C. for 5 hours in a constant temperature bath.

The fiber after the polymerization was immersed in acetone, washed and dried. The fibers were immersed in a solution of 10% by mass of sodium sulfite, 10% by mass of inpropyl alcohol and 80% by mass of water, and a sulfonation reaction was carried out at 80 ° C. for 8 hours. This fiber is added to a 2% by mass cerium nitrate hexahydrate aqueous solution, stirred at room temperature for 1 hour, added to a 0.1N sodium hydroxide aqueous solution, stirred at room temperature for 1 hour, washed with pure water, and washed at 40 ° C. for 15 hours. The desired fibrous adsorbent was obtained by vacuum drying for hours.

The obtained adsorbent was supported on cerium hydrated hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 3 shows other structures and performances.

(Comparative Example 3)
The target adsorbent was obtained by the same procedure as in Example 1 except that 6 nylon fibers (1 filament, diameter of single fiber 575 μm) were used.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 3 shows other structures and performances.

(Example 16)
The target adsorbent was obtained by the same procedure as in Example 8 except that nylon 6 fibers (34 filaments, single fiber diameter 12 μm) were used.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 3 shows other structures and performances.

(Comparative Example 4)
20 g of nylon 6 fibers (235 decitex, 34 filaments, single fiber diameter 28 μm) cut to a length of about 5 cm were added to an aqueous sodium carbonate solution (0.2 g / L) at a bath ratio of 50, and after stirring at room temperature for 30 minutes, It was washed with pure water. The nylon 6 fibers were arranged and subjected to corona discharge treatment under a nitrogen atmosphere with a surface treatment strength of 30 W / min / m ² . While stirring 1 L of a 0.05 M cerium nitrate hexahydrate aqueous solution, 1 L of a 0.2N sodium hydroxide aqueous solution was gradually added, and the mixture was stirred at room temperature for 1 hour to prepare a dispersion of hydrated cerium oxide particles. The obtained nylon 6 fibers were immersed at room temperature for 1 day. Then, it was washed with water to remove excess particles and vacuum dried at 40 ° C. for 15 hours to obtain a desired fibrous adsorbent.

In the obtained adsorbent, cerium hydrate was supported only on the surface of the fiber. Table 3 shows other structures and performances.

(Example 17)
The target adsorbent was obtained by the same procedure as in Example 8 except that 20 g of nylon 6 spunbonded nonwoven fabric (weight 8 g / m ² , single fiber diameter 20 μm) cut into about 2 cm squares was used.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 3 shows other structures and performances.

(Example 18)
The target adsorbent was obtained by the same procedure as in Example 9 except that 20 g of nylon 6 spunbonded nonwoven fabric (weight 8 g / m ² , single fiber diameter 20 μm) cut into about 2 cm squares was used.
The obtained adsorbent was supported on cerium hydrate, and the ratio of the amount of metal particles to the amount of fiber was continuously changed in the radial direction in the radial cross section of the fiber. Further, the ratios Ma and Mb of the amount of metal particles were calculated by dividing the content of cerium by the content of carbon. Table 3 shows other structures and performances.

From the results of Tables 1 to 3, in each of Examples 1 to 18, the arsenic removal rate was 90% or more even when the BV value was 8000 or more, the adsorptivity was excellent, and the reproducibility was 70% or more. .. On the other hand, in Comparative Examples 1 to 4, both adsorptivity and reproducibility could not be achieved.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the intent and scope of the invention. This application is based on a Japanese patent application filed on September 30, 2020 (Japanese Patent Application No. 2020-164826) and a Japanese patent application filed on February 26, 2021 (Japanese Patent Application No. 2021-029592). , The whole is incorporated by citation.

The present invention is an adsorbent having excellent adsorptivity and reproducibility of the adsorbent in recovering valuable substances and removing harmful substances in a water treatment process. It can be preferably used for recovery of rare metals such as chromium, nickel, cobalt and antimony contained in factory wastewater, removal of arsenic and fluorine contained in groundwater, and removal of boron contained in seawater.

1: Fibrous adsorbent 3: Outer surface 5: Inner surface 7: Hollow fiber fibrous adsorbent

Claims

An adsorbent having fibers having a diameter of 1 to 500 μm and metal particles supported on the fibers.
The adsorbent contains 15 to 95 parts by mass of the metal particles per 100 parts by mass.
An adsorbent, characterized in that the crystallite size of the metal particles is 1 to 30 nm.
In the radial cross section of the fiber, the ratio of the amount of metal particles to the amount of fiber changes continuously in the radial direction, and the metal with respect to the amount of fiber at the position a at a depth of 0.1 μm from the outer surface to the inside of the fiber. The ratio Ma of the amount of particles and the ratio Mb of the amount of metal particles to the amount of fibers at the center position b of the cross section satisfy 0.5 ≦ Mb / Ma ≦ 0.95.
The adsorbent according to claim 1.
The metal particles are particles containing at least one selected from the group consisting of sodium, magnesium, aluminum, calcium, titanium, manganese, iron, copper, zirconium, silver, lanthanum and cerium.
The adsorbent according to claim 1 or 2.
The metal particles contain cerium and
The weight ratio (Ce3: Ce4) of trivalent cerium Ce3 and tetravalent cerium Ce4 in the cerium is 20:80 to 1:99.
The adsorbent according to any one of claims 1 to 3.
The fiber is a porous fiber.
The adsorbent according to any one of claims 1 to 4.
The porous fiber is a hollow fiber.
The adsorbent according to claim 5.
The hollow fiber has a uniform hole structure from the outer surface to the inner surface.
The adsorbent according to claim 6.