JP2007231285A - Porous cellulose carrier and method for selectively separating metal therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent which has high affinity to metals, especially heavy metals, such as mercury, copper and lead, and selectively adsorbs the metals. <P>SOLUTION: This cellulose comprises cellulose which contains glucose units having polyethylene imine side chains and is porous. The cellulose has selective affinity to metals, especially heavy metals. Porous cellulose to which polyethylene imine is graft-introduced can further improve the affinity to the heavy metals, and is thereby used as a metal adsorbent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to a polymer-modified porous cellulose that has a high affinity for metals, particularly heavy metals such as mercury, copper, and lead, and selectively adsorbs them, and selective heavy metals using the same. It relates to a separation method.

BACKGROUND OF THE INVENTION The establishment of a method that can selectively separate metals has a wide range of applications. For example, removing metals, especially heavy metals, from wastewater is very important from the standpoint of environmental protection because metals are often toxic. Furthermore, it can be said that it is more preferable if heavy metals from waste water can be recovered and reused.

  Conventionally, as a metal isolation or separation method, for example, a so-called precipitation method in which an anion that forms a salt having a large solubility constant is selected and added is known. Furthermore, a method using an ion exchange resin, a method using a chelating agent, and the like are known.

Summary of the Invention

  The inventors of the present invention have recently found that porous cellulose bonded with polyethyleneimine has a high affinity for metals, particularly heavy metals such as mercury, copper, and lead, and selectively adsorbs them. It was. In addition, it has been found that cellulose obtained by grafting polyethyleneimine with an appropriate polymer interposed between cellulose and cellulose further improves the affinity for heavy metals. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide a polymer-modified porous cellulose that has a high affinity for metals, particularly heavy metals, and selectively adsorbs them.

  Another object of the present invention is to provide a method for selectively adsorbing metals, particularly heavy metals, and removing or recovering them.

  And the porous cellulose by this invention is a cellulose which consists of a cellulose which contains the glucose unit which has a side chain which has the following repeating unit (I) as the 1st aspect, and this cellulose is porous. .

^{_{- (NR 1 -CH 2 CH 2}} ) n- (I)
(In the formula, R ¹ represents a bond to a hydrogen atom or a glucose unit, and n represents an integer of 1 or more.)
The porous cellulose according to the present invention is a cellulose comprising a cellulose comprising a glucose unit having a side chain having the following repeating unit (II) as a second embodiment, and the cellulose is porous. .

（式中、
Ｒ² は、水素原子またはメチル基を表し、
Ｒ³ は、基−ＣＯ−、基−ＣＯ−Ｏ−ＣＨ₂ ＣＨＲ⁴ ＣＨ_2-（ここで、Ｒ⁴ は−ＯＨまたは−ＳＨを表す）、または基−(p- フェニレン）−( ＣＨ₂ ) ｑ−ＣＨＲ⁵ ＣＨ₂ −（ここで、ｑは１または２の整数を表し、Ｒ⁵ は−ＯＨまたは−ＳＨを表す）を表し、
ｎおよびｐは１以上の整数を表し、
Ａはグルコース単位への結合を表す）
また本発明による多孔質セルロースは、その第三の態様として、下記の繰り返し単位（III ）を有する側鎖を有するグルコース単位を含んでなるセルロースからなり、かつ該セルロースが多孔質であるセルロースである。

(Where
R ² represents a hydrogen atom or a methyl group,
R ³ represents a group —CO—, a group —CO—O—CH ₂ CHR ⁴ CH ₂₋ (wherein R ⁴ represents —OH or —SH), or a group — (p-phenylene) — (CH ₂ ) q-CHR ⁵ CH ₂ — (wherein q represents an integer of 1 or 2, R ⁵ represents —OH or —SH),
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit)
Moreover, the porous cellulose according to the present invention is a cellulose comprising a cellulose comprising a glucose unit having a side chain having the following repeating unit (III) as a third embodiment, and the cellulose is porous. .

（式中、
Ｒ⁶ は、基−ＣＯＨまたは基−ＣＯ−低級アルキルを表し、
Ｘは、ハロゲン原子を表し、
ｎおよびｐは１以上の整数を表し、
Ａはグルコース単位への結合を表す）
また本発明による多孔質セルロースは、その第四の態様として、下記の繰り返し単位（IV）を有する側鎖を有するグルコース単位を含んでなるセルロースからなり、かつ該セルロースが多孔質であるセルロースである。

(Where
R ⁶ represents a group —COH or a group —CO-lower alkyl,
X represents a halogen atom,
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit)
Moreover, the porous cellulose according to the present invention is, as a fourth aspect thereof, composed of cellulose comprising a glucose unit having a side chain having the following repeating unit (IV), and the cellulose is porous. .

（式中、
Ｒ⁷ は、水素原子、メチル基、またはフェニル基を表し、
Ｒ⁸ は、基−ＣＯ−Ｏ−（ＣＨ２）ｒ−（ここで、ｒは１〜６、好ましくは１〜４の整数を表す）、基−（p-フェニレン）−（ＣＨ２）ｒ−（ここでｒは前記と同義である）、基−（ＣＨ２）ｒ−（ここでｒは前記と同義である）、または基p-フェニレンを表し、
Ｘは、ハロゲン原子を表し、
ｎおよびｐは１以上の整数を表し、
Ａはグルコース単位への結合を表す）

(Where
R ⁷ represents a hydrogen atom, a methyl group, or a phenyl group,
R ⁸ is (wherein, r is 1 to 6, preferably an integer of 1 to 4) group -CO-O- (CH2) r-, group - (p-phenylene) - (CH2) r- ( Wherein r is as defined above, a group — (CH 2) r — (where r is as defined above), or a group p-phenylene,
X represents a halogen atom,
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit)

Detailed description of the invention

Repeating units (I), (II), (III), and (IV)
According to the first aspect of the present invention, the cellulose comprises glucose having a side chain having the repeating unit (I). This repeating unit (I) is polyethyleneimine. In other words, the cellulose of the first embodiment according to the present invention can be said to be cellulose into which polyethyleneimine has been introduced.

  According to the preferable aspect of this invention, the molecular weight of the side chain part which has repeating unit (I) is 70,000 or less, More preferably, it is 300-20,000. The terminal group of the repeating unit (I) and the terminal groups of the repeating units (II), (III), and (IV) to be described later are slightly smaller in molecular weight than the molecular weight of these repeating units. Therefore, the type does not greatly affect the properties of the molecule, but can be, for example, hydrogen or an amino group.

According to the second aspect of the present invention, the cellulose comprises glucose having a side chain having the repeating unit (II). Wherein n, in the formula _{- (N-CH 2 CH 2} ) n- moiety that is a value such that the molecular weight comparable to the side chain moiety having the repeating unit (I) is preferable.

According to a preferred embodiment of the present invention, in this second embodiment, R ² represents a hydrogen atom or a methyl group, R ³ represents a group —CO—O—CH ₂ CHR ⁴ CH ₂ — (where R ⁴ represents Represents -OH).

According to a third aspect of the present invention, the cellulose comprises glucose having a side chain having the repeating unit (III). In the formula, the alkyl group of the group —CO-lower alkyl represented by R ⁶ preferably represents C _1-6 alkyl, more preferably C _1-4 alkyl. The halogen atom represented by X represents a fluorine, chlorine, bromine, or iodine atom. Furthermore, n in the formula is a value such that the — (N—CH ₂ CH ₂ ) n— moiety in the formula has a molecular weight comparable to that of the side chain moiety having the repeating unit (I). preferable.

According to a fourth aspect of the present invention, the cellulose comprises glucose having a side chain having the repeating unit (IV). Wherein n, in the formula _{- (N-CH 2 CH 2} ) n- moiety that is a value such that the molecular weight comparable to the side chain moiety having the repeating unit (I) is preferable.

In the present invention, in either the side chain having the repeating unit (I) or the side chain having the repeating unit (II), this side chain is introduced by being substituted with H of the —CH ₂ OH group of glucose. Preferably it is.

Cellulose The cellulose in the present invention is a porous body.
According to a preferred embodiment of the present invention, the cellulose is preferably a foam having a porosity of 80% or more and an average pore diameter of 0.05 to 2.0 mm. More preferred is cellulose having a particle size of 1.0 to 5.0 mm, a porosity of 97% or more, an average pore size of 0.3 to 2.0 mm, and a specific gravity of 1.4 to 1.7 g / cm ³ .

  The cellulose may be either natural cellulose (crystal type I) or regenerated cellulose (crystal type II).

  The cellulose preferably used in the present invention is, for example, a high-purity pulp made from wood is chemically treated to form viscose, a third component is added and mixed to form pores, and the mixture is poured into a mold and heated. It can be obtained by solidifying and removing this third component as appropriate. As the third component, a substance that can be easily removed after foam formation is used. For example, water-insoluble or sparingly soluble crystals, waxes, surfactants having a low HLB value, sublimation substances, and the like are used. This removal operation of the third component is performed according to the property of the third component, for example, by extraction with an organic solvent, sublimation by heating, or the like. According to such a method, a base material having desired physical properties (porosity, pore diameter, etc.) can be easily obtained by appropriately selecting the size, type and blending amount of the third component.

  In the present invention, commercially available cellulose can be used, and examples of preferable cellulose include those commercially available from Biomaterial Co., Ltd. as BM Aquacel (trade name).

Introduction of side chain having repeating unit into cellulose Introduction of side chain having repeating unit (I), (II), (III), or (IV) into glucose unit of cellulose, after synthesizing the side chain, Even if it introduce | transduces it into glucose, after introduce | transducing a functional group into glucose, you may introduce | transduce by polymerizing and growing the chain | strand which has these repeating units through the functional group. Chains having these repeating units can be produced by a purposeful method.

More specifically, the cellulose having a side chain having the repeating unit (I) can be produced as follows. First, after activating the —CH ₂ OH group of glucose with sodium methylate or the like, a functional group such as epoxy is introduced using epichlorohydrin or the like. Furthermore, it can be obtained by reacting cellulose introduced with a functional group and polyethyleneimine at a temperature of about 90 to 100 ° C. in a solvent (for example, DMF) that does not participate in the reaction.
Moreover, among the celluloses having a side chain having the repeating unit (II), those in which R ³ is a group —CO— can be produced as follows. First, polymerization is performed by reacting acrylic acid or methacrylic acid in the presence of cellulose in a suitable solvent (for example, water) at a temperature of 20 to 25 ° C. for 0.5 to 1 hour. Next, the obtained polymer is converted to acid chloride with, for example, thionyl chloride. This acid chloride is reacted with polyethyleneimine in a suitable solvent (for example, tetrahydrofuran) at a temperature of 20 to 25 ° C. for 1 to 2 hours to bond them together by an amide bond.

Of the cellulose having a side chain having the repeating unit (II), R ³ is a group —CO—O—CH ₂ CHR ⁴ CH ₂ — or a group — (p-phenylene)-(CH ₂ ) q-CHR ^5. CH ₂ - in which one can be prepared as follows. First, in the presence of cellulose, glycidyl acrylate, glycidyl methacrylate, thioglycidyl acrylate, thioglycidyl methacrylate, vinyl benzyl glycidyl ester, vinyl phenyl glycidyl ester, vinyl benzyl thioglycidyl ester, or vinyl phenyl thioglycidyl ester in a suitable solvent (for example, , Water) at a temperature of 20 to 25 ° C. for 1 to 2 hours for polymerization. The obtained polymer can be obtained by reacting polyethyleneimine with a suitable solvent (for example, DMF) at a temperature of 90 to 100 ° C. for 3 to 5 hours.

  Moreover, the cellulose which has a side chain which has a repeating unit (III) can be manufactured as follows. First, in the presence of cellulose, α-haloacrylic acid or a lower alkyl α-haloacrylic ester is reacted in a suitable solvent (for example, water) at a temperature of 20 to 25 ° C. for 0.5 to 1 hour. To polymerize. It can be obtained by introducing polyethyleneimine into the obtained polymer in a suitable solvent (for example, DMF) at a temperature of 80 to 100 ° C. for 1 to 2 hours by a quaternization reaction (Mentstock reaction). .

  Moreover, the cellulose which has a side chain which has a repeating unit (IV) can be manufactured according to the manufacturing method of the cellulose which has a side chain which has the said repeating unit (III). That is, in the presence of cellulose, haloalkyl acrylate ester, haloalkyl methacrylate ester, haloalkyl styrene, α- (haloalkyl) styrene, or halostyrene is added in a suitable solvent (for example, water) at a temperature of 20-25 ° C. Polymerize by reacting for ~ 5 hours. It can be obtained by introducing polyethyleneimine into the obtained polymer according to the above quaternization reaction (Menstokin reaction).

After the reaction, it is preferable to remove the unreacted components by thoroughly washing the obtained cellulose.
It will be apparent to those skilled in the art that cellulose having molecular weight and other desired physical properties can be produced by appropriately selecting reaction conditions such as temperature, monomer type, reaction time, and the like.

Selective separation of heavy metals The cellulose according to the present invention has a selective affinity for metals, especially heavy metals. Therefore, the cellulose according to the present invention can be preferably used for selectively separating a metal from a certain system.

  Examples of the metal to which the cellulose according to the present invention has affinity include Hg, Cu, Cd, Pb, Zn, Cr, Co, Ni, Mn, and Al. According to a preferred embodiment of the present invention, the cellulose of the present invention has a high affinity for heavy metals. Particularly preferred heavy metals include Hg, Cu, Cd, and Zn, which have a particularly high selective affinity for Hg.

  The reason why the cellulose according to the present invention has an affinity for metal is presumed to be that a chelate-like structure is formed by coordinating and bonding to a metal ion with a plurality of residue portions containing nitrogen atoms present in the repeating unit. Is done.

  According to a preferred embodiment of the present invention, cellulose having the above repeating unit (II), (III), or (IV) is preferred from the viewpoint of its high adsorption capacity. In the cellulose having the repeating unit (II) (III) or (IV), there can be more residue parts containing a nitrogen atom than in the case of cellulose containing the repeating unit (I). It is considered advantageous because it is relatively free to move and easily captures metal ions.

  Furthermore, the cellulose according to the present invention can be desorbed by once adsorbing a metal and then washing with an acid. Therefore, the cellulose according to the present invention can also be used for metal recovery.

  Furthermore, the affinity of cellulose for metal is maintained after acid washing, and it is advantageous in that it can be reused again for metal isolation.

  The selective separation of the metal by cellulose according to the present invention can be carried out by bringing the solution containing the metal into contact with the cellulose.

  In the cellulose according to the present invention, the adsorption rate is high, so that the metal is adsorbed not only by batch processing but also by continuous processing in which a solution flowing in cellulose is brought into contact.

  According to a preferred embodiment of the present invention, the cellulose according to the present invention has an adsorption capacity of about 300 mg / g with respect to Hg. Further, Cu, Cd, and Zn have adsorption capacities of about 50 mg / g, about 40 mg / g, and about 15 mg / g, respectively.

  Specifically, the cellulose according to the present invention can be effectively used for separation or recovery of metals from industrial wastewater.

  The present invention will be described in detail by the following examples, but the present invention is not limited to these examples.

The material cellulose used was a commercially available product from Biomaterial Co., Ltd. as BM Aquacel (trade name). This cellulose has a highly porous (pore diameter: 200 μm) cubic (1 mm ³ approximation) size.

As a control, a CS-03 adsorbent (pore diameter: 0.15 mm, manufactured by Fuji Boseki Co., Ltd.), which is chitosan modified with a polyamine chelate group, was prepared.
Polyethyleneimine (PEI) was provided by Nippon Shokubai Co., Ltd.
All other reagents were purchased from Wako Pure Chemicals.

Example A1 : Production of porous cellulose Cell-PEI Cellulose (0.50 g) was immersed in dry dimethyl sulfoxide (DMSO) (30.0 ml) at 60 ° C. and stirred for 2 hours. Sodium methylate (26.0 ml) was added to the reaction solution, and the mixture was further stirred at room temperature under a nitrogen stream for 1 hour. The resulting product was washed with dry DMSO.

  Sodium cellulose (1.0 g) was immersed in dry DMSO containing 50.0 ml of epichlorohydrin (78.0 ml) and stirred at 50 ° C. for 2 hours under a nitrogen stream. After the reaction, the produced epoxypropylcellulose was separated, washed with distilled water and ethanol, and then dried under reduced pressure.

  The resulting epoxypropylcellulose (1 g) and PEI (4 times excess, four molecular weights 300, 600, 1200, and 20000) in dimethylformamide (DMF) at 100 ° C. under nitrogen gas. The reaction was continued for 4 hours with constant stirring. The obtained porous cellulose (cell-PEI) was separated by filtration, washed thoroughly with hot water (50 ° C.) and ethanol, and then vacuum-dried.

  Elemental analysis results of the obtained epoxypropylcellulose and cell-PEI were as shown in the following table.

表から明らかなように、１００％に近いエポキシド置換度のエポキシプロピルセルロース担体が得られた。さらに滴定実験によって９９．１％のエポキシドが確認された。

As is apparent from the table, an epoxypropylcellulose carrier having an epoxide substitution degree close to 100% was obtained. Furthermore, 99.1% epoxide was confirmed by titration experiments.

また、Ｃｅｌｌ−ＰＥＩの合成では、用いたＰＥＩの分子量によって、１．６６〜２．０４の範囲のアミン／エポキシド比（すなわち、アミン／グルコース比）の試料が得られた。これらの数値は、一つのＰＥＩ分子が複数のエポキシ基と結合していることを示している。 Cell-PEI was synthesized using PEI having different molecular weights according to the above method. The results of elemental analysis of the obtained Cell-PEI were as shown in Table 2 below.

In the synthesis of Cell-PEI, a sample having an amine / epoxide ratio (ie, amine / glucose ratio) in the range of 1.66 to 2.04 was obtained depending on the molecular weight of PEI used. These numbers indicate that one PEI molecule is bonded to a plurality of epoxy groups.

  Moreover, the porous cellulose-ethylenediamine (Cell-ED) was synthesize | combined by making an epoxy propyl cellulose react with ethylenediamine by the method similarly to the above.

Example A2 : Adsorption of Hg on porous cellulose Cell-PEI Adsorption of Hg on porous cellulose was evaluated as follows.
A predetermined amount of Cell-PEI obtained in Example A1 was added to 20.00 ml of HgCl ₂ salt solution having a concentration of 10 mg / l and equilibrated. The pH of the solution was adjusted with 0.1 mol / l Bis-Tris-0.1 mol / l HCl buffer. This mixture was continuously mixed mechanically with a shaker. After the adsorption was completed, the adsorbent was separated by vacuum filtration, and the concentration of Hg in the filtrate was determined.

For comparison, the same operation as above was performed for cell-ED.
The above results were as shown in FIG. In the figure, Co represents the initial concentration of Hg, and Ce represents the Hg concentration in the filtrate.

Example A3 : Continuous adsorption of heavy metal on porous cellulose Cell-PEI The adsorption capacity of Hg on Cell-PEI was evaluated under the following conditions.

  A cell chromatography column (Amicon Co.) having an inner diameter of 1 cm was packed with cell-PEI adsorbent so as to have a height / diameter ratio of 5.5 (corresponding to 0.2262 g of adsorbent). Approximately 10 mg / l of mercury chloride solution was fed to the column at flow rates of 25, 60, and 120 ml / hour. Mercury ion concentration in the effluent was regularly measured. The result was as shown in FIG.

  Adsorption capacities of 159, 239.0, and 260.0 mg / g were obtained at flow rates of 120, 60, and 25 ml / hr, respectively. Using these values, the adsorption capacity at the minimum flow rate (0 ml / hr) was estimated to be 292.0 mg / g. This value almost coincides with the value obtained from the batch adsorption experiment (288.0 mg / g).

Example A4 : Adsorption of various metals on porous cellulose Cell-PEI The adsorption of various metals shown in FIG. 3 on porous cellulose was measured according to the method described in Example A2 except that the pH was adjusted to 7. did.
The above results were as shown in FIG.

Example A5 : Adsorption and Desorption of Metal First, four groups of 0.0015 g of porous cellulose cell-PEI were immersed in 20 ml of a mercury solution having a mercury concentration of 10 ppm, respectively, to adsorb mercury to the porous cellulose. The amount of mercury adsorbed at this time was in the range of 0.178 to 0.181 mg as shown as Cell-PEI in the first batch of Table 3 below.
These four groups of porous cellulose Cell-PEI were immersed in 0.5 M, 1.0 M, 2.0 M, and 4.0 M hydrochloric acid to desorb mercury. The desorption amount of mercury was shown as the desorption amount of the first batch in Table 3 below.

  The porous cellulose Cell-PEI from which mercury was released was again immersed in 20 ml of a mercury solution having a mercury concentration of 10 ppm to adsorb mercury. As a result, the four groups of porous cellulose each adsorbed the amount of mercury shown as the amount of adsorption in the second batch of Table 3 below.

  These four groups of porous cellulose Cell-PEI were immersed in 4.0 M hydrochloric acid to desorb mercury again. The desorption amount of mercury was as shown as the adsorption amount of the second batch in Table 3 below.

  The porous cellulose Cell-PEI from which the mercury was thus removed was immersed again in 20 ml of a mercury solution having a mercury concentration of 10 ppm to adsorb the mercury. As a result, the four groups of porous cellulose Cell-PEI each adsorbed the amount of mercury shown as the amount of adsorption in the third batch of Table 3 below.

  As is clear from the above results, the metal adsorbed on the porous cellulose Cell-PEI can be desorbed by hydrochloric acid. In this experimental example, by using 4.0 M hydrochloric acid, the adsorbed mercury was almost completely desorbed. Moreover, although the desorption of mercury was repeated twice, the mercury adsorption ability of the porous cellulose Cell-PEI was not observed.

Example B1 : Production of porous cellulose poly (CGMAPEI) The reaction temperature was controlled at 20 ° C using a water bath. A mixture of a predetermined amount of cellulose and water was first heated for 15 minutes to remove a trace amount of air trapped inside the porous cellulose, and then allowed to cool to the reaction temperature in a nitrogen gas atmosphere. Kraft polymerization was performed by adding glycidyl methacrylate, stirring vigorously at 300 rpm, and adding a solution of cerium (IV) ammonium nitrate (CAN) (0.1 M). After completion of the reaction, the resulting poly (cellulose-glycidyl methacrylate) product was isolated, washed with tetrahydrofurfuryl and vacuum dried.

  Subsequently, according to the Cell-PEI synthesis method described in Example A1, polyethyleneimine (molecular weight 600) was introduced into the poly (cellulose-glycidyl methacrylate) obtained above (in DMF, 100 ° C.), and porous cellulose poly ( CGMMAPEI) was obtained.

The elemental analysis and calculated composition of Cell-PEI and poly (cell-GMA-PEI) synthesized at various polymerization times were as shown in Table 4 below. Elemental analysis confirmed poly (CGMAPEI) with a higher degree of amine substitution than in the case of Cell-PEI. Graft polymerization has been shown to introduce epoxides at higher densities.

Example B2 : Production of porous cellulose poly (CGMAPEI) Porous cellulose poly (CGMAPEI) was synthesized by changing the concentration of initiator CAN in the cellulose weight ratio in the method described in Example B1. Elemental analysis of the synthesized porous cellulose was as shown in Table 5 below.

グリジルメタクリレートの架橋は、ＣＡＮとグルコース（セルロースの構成単位）の比ＣＡＮ／Ｇｌｕが１．５のとき特に高かった。

The crosslinking of glycidyl methacrylate was particularly high when the ratio CAN / Glu of CAN to glucose (cellulose unit) was 1.5.

Example B3 : Adsorption of heavy metal to porous cellulose poly (CGMAPEI) 15.00 ml of various metal solutions with a concentration of 10 mg / l are contacted with and equilibrated with poly (CGMAPEI) prepared by the methods of Examples B1 and B2. thing

The metal was adsorbed by The adsorption temperature and pH conditions were 25 ° C. and pH 7, respectively. After adsorption, the porous cellulose was separated and the equilibrium metal concentration in the filtrate was determined.

The results were as shown in FIG. 4 for the porous cellulose synthesized in Example B1 and in FIG. 5 for the porous cellulose synthesized in Example B2.
Moreover, the adsorption ability was similarly evaluated about cell-PEI and CS-03 for the comparison.

  As is apparent from FIG. 4, adsorption capacities of 350 mg / g, 45 mg / g, 8.5 mg / g, and 17.5 mg / g were achieved for Hg, Cu, Co, and Zn, respectively. Even poly (CGMAPEI) 30 min with the lowest amine content had higher metal affinity than Cell-PEI for the three metals.

Example B4 : Continuous adsorption of heavy metal on porous cellulose poly (CGMAPEI) The metal adsorption capacity on poly (CGMAPEI) was determined under the following conditions.
The flow rate was 60 ml / hour, and Cu, Co, and Zn were measured according to Example A3.
The result was as shown in FIG.
The concentration of the effluent decreased to a concentration of ppb level. For Co and Zn, the residual concentration decreased to 0.5 ppm and 0.05 ppm, respectively.

Example B5 :
In addition, an experiment was conducted assuming wastewater treatment in which different metals are simultaneously adsorbed on the column.
Specifically, first, 0.83 g of porous cellulose poly (CGMAPEI) was packed in a column having an inner diameter of 1 cm so that the height / diameter was 5.5. An aqueous solution containing all of Ni, Pb, Zn, Cd, Cr, Al, Co, Mn, Cu, and Hg at a concentration of 10 ppm was passed through the column at a flow rate of 60 ml / hour.
The ratio of each metal concentration in the effluent at that time to the initial concentration was plotted against the effluent amount. The result was as shown in FIG.

It is a figure which shows the relationship between the adsorption amount of Hg to the porous cellulose by this invention, and pH. It is a figure which shows the continuous adsorption | suction of the heavy metal to the porous cellulose by this invention. It is a figure which shows the adsorption amount of the various heavy metals to the porous cellulose by this invention. It is a figure which shows the adsorption amount of various heavy metals to the porous cellulose by this invention by which the polyethyleneimine was grafted. It is a figure which shows the adsorption amount of various heavy metals to the porous cellulose by this invention by which the polyethyleneimine was grafted. It is a figure which shows the continuous adsorption amount of the various heavy metal to the porous cellulose by this invention by which the polyethyleneimine was grafted. It is a figure which shows the amount of adsorption | suction of the heavy metal to the porous cellulose by this invention at the time of making a waste water treatment assume and adsorb | sucking a different metal to a column simultaneously.

Claims (13)

The cellulose which consists of a cellulose containing the glucose unit which has a side chain which has the following repeating unit (I), and this cellulose is porous.
^{_{- (NR 1 -CH 2 CH 2}} ) n- (I)
(In the formula, R ¹ represents a bond to a hydrogen atom or a glucose unit, and n represents an integer of 1 or more.)   The cellulose of Claim 1 or 2 whose molecular weight of the side chain part which has a repeating unit (I) is 70,000 or less. The cellulose which consists of a cellulose containing the glucose unit which has a side chain which has the following repeating unit (II), and this cellulose is porous.

(Where
R ² represents a hydrogen atom or a methyl group,
R ³ represents a group —CO—, a group —CO—O—CH ₂ CHR ⁴ CH ₂₋ (wherein R ⁴ represents —OH or —SH), or a group — (p-phenylene) — (CH ₂ ) q-C

HR ⁵ CH ₂ — (wherein q represents an integer of 1 or 2, R ⁵ represents —OH or —SH),
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit) The cellulose according to claim 3, wherein R ² represents a hydrogen atom or a methyl group, and R ³ represents a group —CO—O—CH ₂ CHR ⁴ CH ₂ — (wherein R ⁴ represents —OH). The cellulose which consists of a cellulose which contains the glucose unit which has a side chain which has the following repeating unit (III), and this cellulose is porous.

(Where
R ⁶ represents a group —COH or a group —CO-lower alkyl,
X represents a halogen atom,
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit) The cellulose which consists of a cellulose containing the glucose unit which has a side chain which has the following repeating unit (IV), and this cellulose is porous.

(Where
R ⁷ represents a hydrogen atom, a methyl group, or a phenyl group,
R ⁸ is a group —CO—O— (CH 2) r — (where r represents an integer of 1 to 6), a group — (p-phenylene) — (CH 2) r — (where r is as defined above). Represents the group-(CH2) r- (wherein r is as defined above), or the group p-phenylene,
X represents a halogen atom,
n and p represent an integer of 1 or more,
A represents a bond to a glucose unit) The side chain represented by the repeating unit (I), (II), (III), or (IV) is introduced by substituting with H of —CH ₂ OH of glucose. Cellulose according to any one of the above.   The cellulose according to any one of claims 1 to 7, wherein the cellulose is a foam having a porosity of 80% or more and an average pore diameter of 0.05 to 2.0 mm. The cellulose according to claim 8, wherein the cellulose has a particle size of 1.0 to 5.0 mm, a porosity of 97% or more, an average pore size of 0.3 to 2.0 mm, and a specific gravity of 1.4 to 1.7 g / cm ^3. .   The cellulose according to any one of claims 1 to 9, which is used for selective separation of metals.   The cellulose according to claim 10, wherein the metal is a heavy metal.   A method for selectively separating a metal, comprising a step of bringing a solution containing a metal into contact with the cellulose according to any one of claims 1 to 9.   The method of claim 12, wherein the metal is a heavy metal.

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