JP2013136046A - Ion adsorbent and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion adsorbent which adsorbs anion compounds and radioactive substances adsorbed by anions, especially cesium, from solid materials, e.g., soil.SOLUTION: The ion adsorbent is produced by modifying a cotton-like article, a nonwoven fabric, a thread, a woven fabric or a knitted article, containing cellulose fiber, with a compound having a cationic functional group. The compounds having a cationic functional group include amines, polyamines, polyimines, quaternary ammonium salts and poly quaternary ammonium salts. The ion adsorbent is manufactured by a method including a scouring step of treating a cotton-like article, a nonwoven fabric, a thread or a knitted article, containing cellulose fiber, with an aqueous solution of a surfactant, a cleaning step, a positive charge treatment step of modifying the material with the compound containing a cationic functional group, and a cleaning and drying step.

Description

  The present invention relates to an ion adsorbent, a method for producing an ion adsorbent, and an ion adsorption method using the same, and in particular, from soil, road surface, waste liquid, and the like, anions such as silicon and arsenic, and further potassium, copper, iron, and the like The present invention relates to a method of effectively adsorbing cations to remove anions and a method of recovering suspended substances in liquid.

  Recently, as various kinds of chemical substances are manufactured and used, the opportunities for these chemical substances to come in contact with in daily life are increasing. In addition, these chemical substances may be polluted by the air from the factory and accumulate on the road surface and soil. Many of these substances have harmful effects on human health and ecosystems. In Japan, environmental standards are stipulated, and some metals and heavy metals are specified. For example, it is necessary to remove heavy metal anions including chromium, selenium, arsenic and the like.

  Arsenic compounds are substances that have carcinogenicity as well as strong toxicity. Arsenic has been widely used for metal scouring, pharmaceuticals, etc., but has recently been used in the manufacturing process of semiconductors and ceramics. In recent years, it is often dispersed in waste water or soil.

  Recently, radioactive contamination has been a problem. In particular, the removal of cesium is a very serious problem because of its long half-life. It is believed that cesium is scattered in the atmosphere, accumulates on soil and road surfaces with rain, and further accumulates in drains. Adsorption and removal of cesium deposited on these is an important issue.

  JP 2007-117923 A (Patent Document 1) discloses a fine product obtained by drying a precipitation product obtained by adding an alkali to an iron ion solution and neutralizing to pH 4 to 8 at 60 to 100 ° C. An anion adsorbent obtained by heating and sintering a mixture of a crystalline iron hydroxide material and a synthetic resin powder is disclosed.

  Japanese Patent Application Laid-Open No. 2003-154263 (Patent Document 2) discloses a metal ion adsorbent made of a film obtained by grafting poly (meth) acrylate to a porous polyethylene film.

  Japanese Patent Application Laid-Open No. 2011-162608 (Patent Document 3) discloses a novel cationized microfibrillated plant fiber and a method for producing the same. However, the adsorption of an anionic substance is disclosed. Not.

JP 2007-117923 A JP 2003-154263 A JP 2011-162608 A

  The anion adsorbent disclosed in Patent Document 1 adjusts the pH range in a solution and cannot be applied to solid substances such as soil. Further, the metal ion adsorbent disclosed in Patent Document 2 is intended to remove metal ions from an aqueous solution, and is not removed from solid matter such as soil. It does not adsorb radioactive substances such as cesium.

  The present invention, unlike conventional adsorbents, provides an ion adsorbent that adsorbs anionic compounds, more particularly radioactive substances adsorbed on anions from solid substances such as soil, and uses the ion adsorbent. It is an object of the present invention to provide a method for adsorbing ions and a method for collecting suspended substances in liquid.

  The present invention is an ion adsorbent obtained by modifying a cotton-like product, cellulose, yarn, woven fabric or knitted fabric containing cellulose fibers with a compound having a cationic functional group. The compound having a cationic functional group is preferably an amine, polyamine, polyimine, quaternary ammonium salt or polyquaternary ammonium salt.

  Other embodiments of the present invention include a scouring step, a washing step, a cationic functional group-modified compound containing a cellulose fiber, a scouring step of treating an aqueous surfactant solution with a non-woven fabric, yarn, woven fabric or knitted fabric. The present invention relates to a method for producing an ion adsorbent comprising a charge treatment step and a washing / drying step.

  Furthermore, another embodiment of the present invention relates to an ion adsorption method, wherein the ion adsorbent is brought into contact with soil or soil suspension water to adsorb a substance having an anionic functional group. Here, the substance having an anionic functional group is an organic compound, a clay mineral, or a silicate.

  Furthermore, in another embodiment of the present invention, the flocculant and the ion adsorbent are introduced into soil suspension water containing a radioactive substance (that is, by using the ion adsorbent and the flocculant in combination), In particular, the present invention relates to a method for efficiently recovering a radioactive substance and a substance containing an anionic functional group. Here, the order of adding the flocculant and the ion adsorbent into the liquid is not particularly limited, and either of them may be input first or simultaneously. Here, the flocculant is preferably an anionic flocculant.

  As described above, in the form of the invention in which the ion adsorbent and the flocculant are used in combination, the recovery target may be any substance that can be aggregated by the coagulant used in combination among the suspended substances in liquid. It is not limited to substances (charged substances) and substances containing radioactive substances. Examples of the dispersion system to which the embodiment of the present invention can be applied include natural water such as river water and seawater, hot water ejected from a hydrothermal vent on land (hot spring), and ejected from a hydrothermal vent on the seabed (black smoker). And suspensions containing hydrothermal deposits, sediments of hydrothermal deposits, submarine hydrothermal deposits, and multi-metal sulfide deposits.

  Since the adsorbent of the present invention is modified with a compound having a cationic functional group on a cotton-like material, cellulose, non-woven fabric, yarn, woven fabric or knitted fabric containing cellulose fiber, it effectively adsorbs anionic substances in soil. be able to. In particular, when the soil is contaminated with a radioactive substance such as cesium, the radioactive substance can be recovered simultaneously by effectively adsorbing the soil, and the soil contaminated with the radioactivity can be removed. Even when radioactive substances are mixed in the waste water, the radioactive substances can be effectively removed by using the ion adsorbent of the present invention.

  In addition, since the adsorbent of the present invention has a cationic functional group as described above, the suspended substance aggregated by the anionic flocculant (hereinafter also referred to as agglomerate) is effectively recovered in the liquid. be able to. When an anionic flocculant is added to a liquid in which a suspended substance containing an anionic substance is dispersed, an agglomerate composed of the suspended substance and the flocculant is formed. The agglomerate is negatively charged as a whole and easily binds to the adsorbent of the present invention having a cationic functional group. Therefore, by using the adsorbent of the present invention and the flocculant together, it is possible to efficiently recover and remove suspended substances in the liquid, and the suspended substances can save valuable resources such as precious metals and rare metals. When included, they can be easily and efficiently recovered.

<Cotton containing cellulose fiber, non-woven fabric, yarn, woven fabric or knitted fabric>
The cellulose fiber means a fiber containing cellulose in the molecular structure, and broadly means a fiber obtained by pulverizing cotton, wood pulp, vegetable fiber, recycled paper, waste paper, or the like. And what made the cellulose fiber the cotton-like thing, the nonwoven fabric, the thread | yarn, the woven fabric, or the knitted fabric is used for an ion adsorption material. The cellulose fiber may be contained in a cotton-like material, non-woven fabric, yarn, woven fabric or knitted fabric in an amount of 10% by mass or more. For example, it may be used as a synthetic fiber such as nylon, polyester, rayon, or a woven fabric or knitted fabric. Can do.

<Compound with cationic functional group used for modification>
In the present invention, as a compound having a cationic functional group for modifying cellulose fiber, a quaternary ammonium compound having a chlorohydrin group, a quaternary ammonium compound having an epoxy group, a quaternary ammonium compound having a triazine group, poly Examples include allylamine and polyethyleneimine.

  Furthermore, 3-chloro-2-hydroxypropyltrimethylammonium chloride, 2,3-epoxypropylmethylammonium chloride, monochloroethyldiethylamine, glycidyltrimethylammonium chloride, and the like can be used.

  The amount of the compound having a cationic functional group is adjusted in the range of 0.5 to 20 parts by mass, preferably 1 to 6 parts by mass with respect to 100 parts by mass of the cellulose fiber.

<Production method of ion adsorbent>
The method of modifying cellulose fiber with a compound having a cationic functional group includes a scouring step, a water washing step, a positive charge treatment step, and a water washing / drying step on a cellulose fiber non-woven fabric or the like.

(Scouring process)
In the scouring step, the treatment solution is an alkaline solution, for example, 5 to 30% by mass, preferably 10 to 25% by mass NaOH aqueous solution, 0.1 to 5 g / L, preferably 0.3 to 1 g / L interface. Contains an active agent. Here, the surfactant is a polyoxyethylene group, a sugar (sorbitan, sucrose, glucose), a nonionic surfactant having a hydroxy group or the like as a hydrophilic group, a fatty acid salt, a sulfonate, a sulfate, a phosphorus Anionic surfactant having acid ester salt as hydrophilic group, amine salt, quaternary ammonium salt, cationic surfactant having sulfonium salt as hydrophilic group, betaine having amino acid type or quaternary ammonium salt structure Any type of amphoteric surfactant can be used. Preferably, it is an anionic surfactant. In particular, as a suitable surfactant, there is an anionic surfactant such as Saisol 2EX (Daiichi Kogyo Seiyaku Co., Ltd.).

  In the scouring step, the surface of the cellulose fiber is dropped, and the affinity between the surface of the cellulose fiber and the compound containing a cationic functional group can be increased. A scouring treatment is performed by immersing a cellulose fiber nonwoven fabric or the like in the treatment solution. Here, the treatment solution is treated at a temperature of 50 to 100 ° C. for 2 to 10 minutes.

(Washing process)
In the washing step, the alkaline solution and excess surfactant in the refinement step are removed, and the scoured cellulose fiber nonwoven fabric is immersed in a water bath or washed with a shower. The water bath is treated at a temperature of 10 to 40 ° C. for 2 to 10 minutes.

  In addition, prior to the water washing, water washing can be performed. The hot water washing is preferably carried out at 50 ° C. to 90 ° C. for 2 to 10 minutes.

(Positive charge treatment process)
Next, the cellulose fiber nonwoven fabric is subjected to a positive charge treatment step with a compound containing a cationic functional group. After the washing step, the nonwoven fabric is a compound containing a cationic functional group, for example, a quaternary ammonium compound having a chlorohydrin group, a quaternary ammonium compound having an epoxy group, a quaternary ammonium compound having a triazine group, or polyallylamine. Modified with polyethyleneimine.

  As a positively charged treatment solution, an alkaline solution, for example, 5 to 30% by mass, preferably 10 to 30% by mass NaOH aqueous solution, 1.0 to 5.0 g / L, preferably 1.5 to 6.0 g / L. Compounds containing L cationic functional groups are dissolved. Cellulose fiber nonwoven fabric and the like are subjected to a positive charge treatment by being immersed in the treatment solution. Here, the positive charge treatment is performed for 10 to 60 minutes by adjusting the temperature of the treatment solution to 50 to 90 ° C. By this treatment, the cationic functional group is electrostatically bonded or partly chemically bonded to the surface of the cellulose fiber to obtain a modified cellulose fiber.

  In the positive charge treatment step, the cellulose fiber is treated with a chelating agent such as sodium nitrilotriacetate together with an inorganic acid, acrylic acid or the like in order to effectively bind the cellulose fiber to the cationic functional group as a pretreatment. It is preferable.

(Washing / drying process)
The purpose of the washing / drying step is to wash away and remove the alkaline solution and the compound containing unreacted cationic functional groups remaining on the surface of the positively charged cellulose fiber. A modified cellulose fiber nonwoven fabric is immersed in a water bath or washed with a shower. The water bath is treated at a temperature of 10 ° C. to 40 ° C. for 2 to 10 minutes. Prior to the water washing, it is preferable to wash with hot water. The hot water washing is preferably performed at a temperature of 50 ° C. to 90 ° C. for 2 to 10 minutes. In order to remove moisture such as the nonwoven fabric of cellulose fiber washed with water, the cellulose fiber is dried for 10 to 15 minutes at a temperature of 80 ° C. to 100 ° C. with a dryer.

<Ion adsorption method by ion adsorbent>
In order to adsorb an element such as cesium using the ion adsorbent of the present invention, the following method can be employed. The ion adsorbent can adsorb these substances by directly contacting a substance containing an anion or a contaminant such as cesium adsorbed on a substance containing an anion. Moreover, an anion can be removed by making it contact with the solution containing an anion, and making the ion adsorption material adsorb | suck the anion contained in this solution.

  Here, examples of the anion to be removed include anions and fluorine ions containing cesium, molybdenum, chromium, antimony, selenium, arsenic, and boron. Among them, in the anion adsorbent of the present invention and the method of removing anions using them, clay adsorbed with cesium, for example, 55.4% silica, 30.0% aluminum, 7.4% iron, Ca3. 6%, K2.5%, Ti0.8% clay has an adsorption effect together with cesium.

<Disposal of ion adsorbent>
When a radioactive substance is adsorbed on the ion adsorbent of the present invention, it is immersed in sulfuric acid (3.67 to 6.67%), carbonized at 100 to 140 ° C. for about 1 hour, and can be sealed and discarded after volume reduction. . Hydrogen peroxide 10cc / L, No. 1 sodium silicate 5g / L, NaOH (24%) 0.2g / L,
When the treatment at 130 ° C. × 1 hour is performed, the cationic group bonded to the fiber is destroyed, and the radioactive substance can be eluted in water, and can be removed and reduced in volume by passing through a permeable membrane. Also, incinerate in a combustion furnace with an impurity removal bag filter and seal and discard with extracted impurities.

<Regeneration method of ion adsorbent>
The adsorbent adsorbing the anions can be regenerated. For example, the adsorbed anion is eluted by treating the ion adsorbent with an alkaline solution. The alkaline solution used in the method for regenerating the ion adsorbent is not particularly limited, and an aqueous solution such as sodium hydroxide or potassium hydroxide can be used. Moreover, it is preferable that pH of the process liquid at the time of processing with an alkaline solution shall be the range of 13-14, More preferably, it is pH13.5-14. Further, by treating the ion adsorbent adsorbing anions with an alkaline solution, the adsorbed anions can be eluted, and the elements contained in the anions can be recovered.

<Method for recovering suspended matter in liquid by using ion adsorbent and coagulant>
The following method can be employed as a method for recovering suspended matter in liquid using the ion adsorbent and the flocculant of the present invention in combination. The flocculant aggregates suspended substances dispersed in the liquid to form a negatively charged agglomerate. Since the ion adsorbent can adsorb such agglomerates, suspended substances can be efficiently recovered and removed. For example, after collecting soil contaminated with radioactive substances such as cesium and dispersing it in a liquid, agglomerating agent is added to form agglomerates, and the ion adsorbent of the present invention is further added to the ion adsorbent. The agglomerates can be adsorbed to collect contaminants. That is, the method for recovering a suspended substance in a liquid according to the present invention includes a step of aggregating a substance having an anionic functional group in a liquid to form an agglomerate, and the agglomerate and the ion adsorbent according to the present invention. And a method of adsorbing ions.

  Further, in the above method, the method of first adding the flocculant into the liquid is exemplified, but in the method for recovering a suspended substance in liquid according to the present invention, the order of adding the flocculant and the ion adsorbent is limited to this. Instead, the ion adsorbent may be charged into the liquid first, or the ion adsorbent and the flocculant may be charged simultaneously. In these cases, the agglomerates as described above are not formed, but it is possible to improve the adsorption efficiency of the suspended substance on the ion adsorbent as in the case where the agglomerates are formed. In other words, as long as the ion adsorbent of the present invention and the flocculant are used in combination, the effect of the present invention is exhibited. Furthermore, in the above method, as long as the ion adsorbent of the present invention and the flocculant are used in combination, other elements may be used in combination, and even if other elements are used in combination, the effect of the present invention Is indicated.

<Flocculant>
Here, the flocculant used in the above method is not particularly limited, and may be either an inorganic flocculant or an organic flocculant, but is preferably an anionic flocculant. As such a flocculant, for example, Metafloc 30 type (product name: manufactured by Environmental Soken Co., Ltd.), Super Z M-0308CR, ECOHERE 3, AQUARIA-POP WP360, AQUARIA-POP WP460 (all are product names: limited company) KM System), Hymo Lock MS Series, Hymo Lock SS Series, Hymo Lock AP Series (all product names and product numbers: Hymo Co., Ltd.), Sanflock AH Series, Sanflock AS Series, Sanflock R Series (all product names and Part No .: Sanyo Kasei Kogyo Co., Ltd.) Diaflock AP series, Diaflock KA series (both product name and part no .: Daianitrix Co., Ltd.), Akoflock A series (Product name and part no .: MT Akaku Mention may be made of a polymer Co., Ltd.) and the like. Further, even when the aggregating agent is cationic, amphoteric or nonionic, the effect of the present invention is exhibited as in the case of the anionic aggregating agent when the agglomerates are negatively charged as a whole.

[Production method of ion adsorbent]
The ion adsorbents A to C and F of Examples 1 to 4 and the ion adsorbents D, E and G of Comparative Examples 1 to 3 were produced by the following method.

<Example 1: Ion adsorbent A>
(Cellulose fiber)
A cotton non-woven fabric was used as the material. A basis weight of 50 g / m ² , a width of 90 cm, a length of 100 m, and a mass of 4.5 kg were used. A closed cotton dyeing machine was used as the processing machine.

(Scouring process)
To 45 L of water, 360 g of a 24% aqueous solution of NaOH was mixed. Furthermore, as a nonionic surfactant, 22.5 g (0.5 g / L) of SSK-60 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was dissolved to prepare a treatment solution. This treatment solution was adjusted to 100 ° C., and the cotton nonwoven fabric was subjected to immersion treatment for 10 minutes.

(Washing process)
The cotton nonwoven fabric treated in the scouring process was immersed in a hot bath at a temperature of 60 ° C. and washed with hot water for 5 minutes. The treated cotton nonwoven fabric was immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes.

(Positive charge treatment process)
2. Water (45 L) and cationone KCN (quaternary ammonium salt mainly composed of 3-chloro-2-hydroxypropyltrimethylammonium chloride and 2,3-glycidyltrimethylammonium chloride: manufactured by Otsuka Kogyo Co., Ltd.) 375 kg and 2.07 kg of a 24% aqueous solution of NaOH were mixed. This treatment solution was adjusted to 60 ° C., and the cotton nonwoven fabric was immersed for 40 minutes.

(Washing / drying process)
The treated cotton nonwoven fabric was immersed in a warm bath at a temperature of 60 ° C. and washed with hot water for 5 minutes, and then immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes. After the water washing step, the cotton nonwoven fabric was dehydrated with a centrifugal dehydrator and dried at a temperature of 80 ° C. for 10 minutes using a suction conveyor dryer to obtain an ion adsorbent.

<Example 2: Ion adsorbent B>
(Cellulose fiber)
A cotton non-woven fabric was used as the material. A basis weight of 50 g / m ² , a width of 90 cm, a length of 200 m, and a mass of 9.0 kg were used. A closed cotton dyeing machine was used as the processing machine.

(Scouring process)
A treatment solution was prepared by dissolving 150 g of water and 150 g of Saisol 2EX (anionic surfactant: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an anionic surfactant. This treatment solution was adjusted to 60 ° C., and the cotton nonwoven fabric was dipped for 10 minutes.

(Washing process)
The cotton non-woven fabric treated in the hot water washing and scouring process was immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes.

(Positive charge treatment process)
As a pretreatment, water 150L, chelate NTB (nitrilotriacetate sodium: manufactured by Kirest Co., Ltd.) 45g, 62.5% sulfuric acid 59.4g, 80% methacrylic acid 2700g, 0.2% sulfuric acid An aqueous solution containing 18 g of iron and 450 g of 35% hydrogen peroxide was prepared. This treatment solution was adjusted to 90 ° C., and the cotton nonwoven fabric was dipped for 60 minutes. Thereafter, the cotton nonwoven fabric was immersed in a warm bath at a temperature of 60 ° C. and washed with hot water for 5 minutes, and further immersed in a water bath at 30 ° C. and washed with water for 5 minutes.

  To 150 L of water, 3000 g (PAA-15: manufactured by Nitto Bo Medical Co., Ltd.) of 15% aqueous polyallylamine was added. The said cotton nonwoven fabric was immersed for 60 minutes at the temperature of 90 degreeC.

(Washing / drying process)
The cotton nonwoven fabric treated in the scouring process was immersed in a hot bath at a temperature of 60 ° C. and washed with hot water for 5 minutes. Thereafter, the cotton nonwoven fabric treated in the hot water washing and scouring step was immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes. After washing with water, the cotton nonwoven fabric was dehydrated with a centrifugal dehydrator and dried at 80 ° C. for 10 minutes using a suction conveyor dryer to obtain an ion adsorbent.

<Example 3: Ion adsorbent C>
(Cellulose fiber)
A cotton non-woven fabric was used as the material. A basis weight of 50 g / m ² , a width of 90 cm, a length of 200 m, and a mass of 9.0 kg were used. A closed cotton dyeing machine was used as the processing machine.

(Scouring process)
150 g of water and 150 g of Saisol 2EX (anionic surfactant: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added as an anionic surfactant to prepare a treatment solution. This treatment solution was adjusted to 60 ° C., and the cotton nonwoven fabric was dipped for 10 minutes.

(Washing process)
The cotton non-woven fabric treated in the hot water washing and scouring process was immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes.

(Positive charge treatment process)
As pretreatment, 45 g of cherest NTB (sodium nitrilotriacetate: manufactured by Kirest Co., Ltd.) as chelating agent, 59.4 g of 62.5% sulfuric acid, 2700 g of 80% methacrylic acid, 18 g of 0.2% ferrous sulfate An aqueous solution containing 450 g of 35% hydrogen peroxide was prepared. This treatment solution was adjusted to 90 ° C., and the cotton nonwoven fabric was dipped for 60 minutes.

  Thereafter, the cotton nonwoven fabric was immersed in a 60 ° C. warm bath and washed with hot water for 5 minutes, and further immersed in a 30 ° C. water bath and washed with water for 5 minutes.

  A cotton non-woven fabric was immersed in a treatment liquid obtained by adding 450 g of 98% polyethyleneimine (manufactured by Nitto Bo Medical Co., Ltd.) to 150 L of water, and treated by immersing in a water bath at a temperature of 90 ° C. for 60 minutes.

(Washing / drying process)
After washing with water, the cotton nonwoven fabric was dehydrated with a centrifugal dehydrator and dried at 80 ° C. for 10 minutes using a suction conveyor dryer to obtain an ion adsorbent.

<Example 4: Ion adsorbent F>
An ion adsorbent was obtained in the same manner as in Example 1 except that rayon cotton was used as the material.

<Comparative Example 1: Ion adsorbent D>
The same cotton nonwoven fabric as in Example 1 was used, and this was used untreated.

<Comparative Example 2: Ion adsorbent E>
(Cellulose fiber)
A cotton non-woven fabric was used as the material. A basis weight of 50 g / m ² , a width of 90 cm, a length of 200 m, and a mass of 9.0 kg were used. A closed cotton dyeing machine was used as the processing machine.

(Scouring process)
150 g of water was mixed with 150 g of Saisol 2EX (anionic surfactant: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an anionic surfactant to prepare a treatment solution. This treatment solution was adjusted to 60 ° C., and the cotton nonwoven fabric was dipped for 10 minutes.

(Washing process)
The cotton non-woven fabric treated in the hot water washing / scouring process was immersed in a water bath at a temperature of 30 ° C. and washed with water for 5 minutes.

(Positive charge treatment process)
As pretreatment, 45 g of cherest NTB (sodium nitrilotriacetate: manufactured by Kirest Co., Ltd.) as chelating agent, 59.4 g of 62.5% sulfuric acid, 2700 g of 80% methacrylic acid, 18 g of 0.2% ferrous sulfate An aqueous solution containing 450 g of 35% hydrogen peroxide was prepared. This treatment solution was adjusted to 90 ° C., and the cotton nonwoven fabric was dipped for 60 minutes.

  Thereafter, the cotton nonwoven fabric was immersed in a 60 ° C. warm bath and washed with hot water for 5 minutes, and further immersed in a 30 ° C. water bath and washed with water for 5 minutes.

  900 g of soda ash was added to 150 L of water to prepare a treatment solution. And the cotton nonwoven fabric was immersed in the warm bath of the temperature of 85 degreeC, and processed for 30 minutes.

(Washing / drying process)
After washing with water, the cotton nonwoven fabric was dehydrated with a centrifugal dehydrator and dried at 80 ° C. for 10 minutes using a suction conveyor dryer to obtain an ion adsorbent.

<Comparative example 3: Ion adsorbent G>
The same rayon cotton as in Example 4 was used and used as it was untreated.

[Experiment 1: Comparison between cationic group and anionic group]
(A) To a beaker, 10 g of soil, 100 ml of water, and 0.3 ml of a 24% NaOH aqueous solution were added and stirred for 10 minutes.
(B) The cotton nonwoven fabric was added in the amount shown in Table 1 and stirred for 30 minutes.
(C) The cotton nonwoven fabric was taken out from the beaker, washed with water twice with 100 cc of water, dried, and then weighed.
(D) The thing in a beaker was divided into precipitation and supernatant, and the sediment was dried and weighed. The results are shown in Table 1.

  From the results in Table 1, it can be seen that the adsorption rate of Example 1 is 13%, which is significantly higher than 6% and 5% of the adsorption rates of Comparative Examples 1 and 2.

[Experiment 2: Soil adsorption test]
With respect to Examples 2 and 3 and Comparative Example 1, soil adsorption tests were conducted on the ion adsorbents B, C, and D produced by the above method by the following method.
(A) To a beaker, 10 g of soil, 100 ml of water, and 0.3 ml of a 24% NaOH aqueous solution were added and stirred for 10 minutes.
(B) The cotton nonwoven fabric was added in the amount shown in Table 1 and stirred for 30 minutes.
(C) The cotton nonwoven fabric was taken out from the beaker, washed with water with 100 cc of water twice, and then weighed.
(D) The thing in a beaker was divided into precipitation and supernatant, and the sediment was dried and weighed. The results are shown in Table 2.

  From the results of Table 2, the adsorption rates of Examples 2 and 3 are 11.2% and 14.4%, respectively, which are significantly higher than 0.4% of the adsorption rate of Comparative Example 1. I understand that

[Experiment 3: Contaminated grass decontamination test]
Regarding Example 1 and Comparative Example 1, a decontamination test of grass contaminated by the following method was performed on the ion adsorbents A and D produced by the above method.
(A) 6 L of water, 500 g of grass, and 6 ml of 24% NaOH aqueous solution were added to the bucket and stirred for 10 minutes.
(B) The cotton nonwoven fabric was added in the amount shown in Table 1 and stirred for 30 minutes.
(C) The cotton non-woven fabric was taken out from the bucket, squeezed by hand, and water was returned to the bucket.
(D) The radiation dose of the nonwoven fabric, grass and bucket water was measured with a dosimeter. The measurement was performed using TERRA-P + (Terapy Plus) manufactured by ECOTEST, and the results are shown in Table 1.

  From the results in Table 3, the adsorption rate of Example 1 is considerably higher than that of Comparative Example 1.

[Experiment 4: Clay decontamination test]
Regarding Example 1 and Comparative Example 1, a clay decontamination test was conducted in which the ion adsorbents A and D produced by the above method were contaminated by the following method.
(A) 10 L of water, 1 kg of clay and 10 ml of 24% NaOH aqueous solution were added to the bucket and stirred for 10 minutes.
(B) The cotton nonwoven fabric was added in the amount shown in Table 1 and stirred for 30 minutes.
(C) The cotton non-woven fabric was taken out from the bucket, squeezed by hand, and water was returned to the bucket. The supernatant was transferred to another bucket and separated from the residue.
(D) The radiation dose of the work chamber and clay is measured in advance.
(E) The radiation dose of the residue, the nonwoven fabric and the supernatant (treated water) was measured with a dosimeter in the working chamber. The measurement was performed using TERRA-P manufactured by ECOTEST.

  From the results of Table 4, the adsorption rate of Example 1 is considerably higher than that of Comparative Example 1.

[Experiment 5: Decontamination test of sand planted in park]
Regarding Example 1 and Comparative Example 1, a decontamination test of grass contaminated by the following method was performed on the ion adsorbents A and D produced by the above method.
(A) 10 L of water, 1 kg of sand and 10 ml of 24% NaOH aqueous solution were added to the bucket and stirred for 10 minutes.
(B) The cotton nonwoven fabric was added in the amount shown in Table 1 and stirred for 30 minutes.
(C) The cotton non-woven fabric was taken out from the bucket, squeezed by hand, and water was returned to the bucket. The supernatant was transferred to another bucket and separated from the residue.
(D) The radiation dose of the work chamber and clay is measured in advance.
(E) The radiation dose of the residue, the nonwoven fabric and the supernatant (treated water) was measured with a dosimeter in the working chamber. The measurement was performed using TERRA-P manufactured by ECOTEST.
(F) The precipitate was dried and weighed.

  Table 5 shows the measurement results. From the results in Table 5, the adsorption rate of Example 1 is considerably higher than that of Comparative Example 1.

[Experiment 6: Radioactivity measurement of drainage by high-pressure washing work in parking lot]
Regarding Example 1, the radioactivity of the waste water was measured for the ion adsorbent A produced by the above method by the following method.
(A) 10 L of high-pressure washing waste liquid and 10 ml of 24% NaOH aqueous solution were added to the bucket and stirred for 10 minutes.
(B) 250 g of a cotton nonwoven fabric was added and stirred for 40 minutes.
(C) The cotton non-woven fabric was taken out from the bucket, squeezed by hand, and water was returned to the bucket.
(D) Radioactivity was measured with an AT1320A radioactivity measuring machine manufactured by ATOMTEX.

  Table 6 shows the measurement results. From the results in Table 6, it can be seen that the adsorption rate of Example 1 is extremely high.

[Experiment 7: Radioactive substance removal test from radioactive substance decontamination effluent]
Regarding Example 4, using the ion adsorbent F produced by the above method, a radioactive substance removal test from waste water by high-pressure washing work was performed by the following method.
(A) Collecting wastewater containing radioactive cesium generated by high-pressure washing work (hereinafter also referred to as high-pressure washing wastewater) and using a germanium semiconductor detector (model “GC2520”: manufactured by Camberra), the ratio of high-pressure washing wastewater Radioactivity was measured.
(B) 1.7 L of high-pressure washing waste water is put into the bucket, and 0.68 g (0.4 g / L) of Metafloc 30 type (inorganic-based flocculant: manufactured by Environmental Soken Co., Ltd.) is added as an anionic flocculant. Agitation and precipitation of the suspended material was carried out.
(C) 51 g (30 g / L) of ion adsorbent F was added and stirred. It was confirmed by visual observation that the aggregated sediment and suspended substances were sufficiently adsorbed to the ion adsorbent F, and the ion adsorbent F was recovered from the bucket.
(D) After collecting the ion adsorbent F, the ion adsorbent F was squeezed to collect the wastewater contained in the ion adsorbent F. And the collect | recovered waste_water | drain and the waste_water | drain left in the bucket were mixed. Subsequently, the specific activity of the mixed waste water was measured in the same manner as described above.

  The test results are shown in Table 7. From the results in Table 7, it was confirmed that an extremely high decontamination effect was obtained by using the ion adsorbent of Example 4 and the flocculant in combination. Although the details of the mechanism of action in which this effect is manifested are not clear, the present inventors, for this reason, as described above, agglomerates with a negative charge are formed by the flocculant. It is presumed that the adsorption of the radioactive substance is promoted not only by the adsorption to the surface but also by the interaction between the ion adsorbent of the present invention and the anionic flocculant.

[Experiment 8: Adsorption test using suspension of kaolin clay]
Regarding Example 4, the kaolin clay adsorption capacity of the ion adsorbent F produced by the above method was evaluated by the following method using a commercially available clay and kaolin suspension (hereinafter also referred to as kaolin suspension). did.
(A) A kaolin suspension having a concentration of 1% was prepared.
(B) To a glass beaker, 100 mL of kaolin suspension and 0.1 g (1 g / L) of ion adsorbent F were added and stirred for a short time.
(C) Next, 0.02 g (0.2 g / L) of a flocculant (Metafloc 30 type) was added, and stirring was further continued.
(D) After stirring for 1 minute, the ion adsorbent was recovered, and the liquid was squeezed out and dried. Similarly, after 1.5 minutes of stirring, 2 minutes of stirring, 3 minutes of stirring, and 5 minutes of stirring, the ion adsorbent was recovered, and the liquid was squeezed out and dried.
(E) From the weight after the test and the weight before the test of the ion adsorbent, the adsorption rate was determined by the following formula (I).
(F) The adsorption rates of the ion adsorbent F and the ion adsorbent G were determined in the same manner as in (a) to (e) except that the flocculant was not added.

  Adsorption rate (%) = {(weight after test / weight before test) -1} × 100 (I)

  The test results are shown in Table 8. In the table, Example 5 shows a case where the ion adsorbent of Example 4 and the flocculant are used in combination. From the results of Table 8, the adsorption rate of the ion adsorbent of Example 4 is better than that of Comparative Example 3. And when the ion adsorbent of Example 4 and the coagulant | flocculant are used together (namely, in the case of Example 5), the adsorption rate has improved dramatically.

  Although the details of the mechanism of action in which this effect appears are unknown, the present inventors presume the mechanism as follows. In Experiment 8, the ion adsorbent is first introduced into the liquid, and then the flocculant is introduced. Therefore, unlike Experiment 7, no agglomerates are formed. Nevertheless, the improvement in the adsorption rate is expected to be due to the interaction between the complex composed of the flocculant and the suspended solids in the liquid and the ion adsorbent of the example. The That is, the aggregating agent has a function as an adsorption accelerator, and the function is expected to work effectively particularly when combined with the ion adsorbent of the example.

[Experiment 9: Adsorption test in seawater or sodium chloride solution]
Regarding Example 4, the adsorption ability of the ion adsorbent F produced by the above method in seawater or sodium chloride solution was evaluated by the following method.
(A) In a glass beaker, seawater or a 3% sodium chloride solution and kaolin were added and stirred to uniformly disperse kaolin to obtain a kaolin suspension having a kaolin concentration of 3%.
(B) To a glass beaker, 100 mL of the kaolin suspension obtained as described above and 0.1 g (1 g / L) of the ion adsorbent F were added and stirred for a short time.
(C) Next, 0.02 g (0.2 g / L) of a flocculant (Metafloc 30 type) was added, and stirring was further continued.
(D) After stirring for 2 minutes, the ion adsorbent was recovered, the liquid was squeezed out and dried.
(E) From the weight after the test and the weight before the test of the ion adsorbent, the adsorption rate was determined by the above formula (I).
(F) Except not adding a flocculant, the adsorption rate of the ion adsorbent F and the ion adsorbent G was determined in the same manner as in (a) to (e).

  The test results are shown in Table 9. In the table, Example 5 shows a case where the ion adsorbent of Example 4 and the flocculant are used in combination. From the results of Table 9, it can be confirmed that the method of Example 5 can obtain an extremely high adsorption capacity even in seawater or sodium chloride solution, and is an extremely efficient method for recovering suspended matter in liquid. It was.

  Moreover, from the results in Table 9, in Example 5, the adsorption rate in seawater is slightly lower than in the 3% sodium chloride solution. This is considered to be because the effect of the flocculant is diminished by hardness components (magnesium ions, calcium ions, etc.) contained in the seawater. Therefore, for example, when applying the method for recovering a suspended substance in liquid of the present invention to seawater or natural water containing a hardness component, an ion adsorbent (that is, a cation exchanger) made of anionized fibers is used. It is considered that a higher adsorption ability can be obtained by previously passing through the treated water and then applying the method for recovering a suspended substance in liquid of the present invention.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples. It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The ion adsorbent in the present invention effectively removes solids such as soil, absorbs anions or radioactive substances, and is effectively used for decontamination of soil contaminated with radioactive substances such as cesium. it can. Further, for example, when the suspended material in liquid contains mineral resources such as noble metals and rare metals, it can be used for easy and efficient recovery of them. Furthermore, it can be used for a system for softening seawater or natural water.

Claims (6)

  An ion adsorbent obtained by modifying a cotton-like material, cellulose, woven fabric, yarn or knitted fabric containing cellulose fibers with a compound having a cationic functional group.   The ion adsorbent according to claim 1, wherein the compound having a cationic functional group is an amine, a polyamine, a polyimine, a quaternary ammonium salt or a polyquaternary ammonium salt.   A scouring step, a washing step, a positive charge treatment step for modifying with a compound containing a cationic functional group, and a washing / drying step for cotton-like materials, cellulose, yarn, woven fabric or knitted fabric containing cellulose fiber. A method for producing an ion adsorbent comprising:   A method for adsorbing ions, comprising bringing the ion-adsorbing material according to claim 1 into contact with soil or soil suspension water to adsorb a substance having an anionic functional group.   The method for adsorbing ions according to claim 4, wherein the substance having an anionic functional group is an organic compound, a clay mineral, or a silicate.   A method for recovering a suspended substance in liquid, comprising using the ion adsorbent according to claim 1 and a flocculant in combination.