JP2013079415A - Noble metal recovering cartridge filter using chitosan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a noble metal recovering cartridge filter using chitosan, making it possible to efficiently recover noble metals from acidic solution represented by industrial waste liquid; a method for manufacturing the same; and a method for recovering the noble metal using the same.SOLUTION: The noble metal recovering cartridge filter having a porous core 1 at least one end which is opened and a cartridge filter base material 2 wound around the porous core is characterized in that chitosan derivative is held in the cartridge filter base material. The chitosan derivative represented by a formula (I) contains glucosamine derivative constituting the chitosan.

Description

  The present invention relates to a noble metal recovery cartridge filter using chitosan that enables efficient recovery of a noble metal from an acid solution typified by industrial waste liquid, a method for producing the same, and a method for recovering a noble metal using the same.

  As an adsorbent for precious metals from acid solutions typified by industrial waste liquids, ion exchange resins and the like are widely known. However, in the case of an ion exchange resin, the current situation is that it is not widespread due to the limited flow rate during processing and the difficulty of desorption after adsorption of noble metals.

  Chitosan, which is a natural polysaccharide, has been known for a long time to have an ability to adsorb noble metal ions, and the development of an adsorbent using the ability to adsorb noble metal ions is in progress. However, in many cases, the form of the adsorbent using chitosan is particulate as in the case of the ion exchange resin, which is a complicated process for industrial production, and the same as in the case of the ion exchange resin. In addition, there is a practical problem that the flow rate during processing is limited.

  In addition, acid solutions represented by industrial waste liquids contain a large amount of metals such as iron, copper, aluminum, nickel, and cobalt. Therefore, development of a highly selective chitosan derivative for highly selectively adsorbing and separating only a trace amount of noble metal ions from these metals is required.

  Furthermore, since the adsorption rate of noble metal ions is generally slow, in order to industrialize the separation / recovery process of noble metal ions, the development of an adsorbent / separation material that can be easily eluted and reused, It is necessary to increase the speed.

  Patent Document 1 describes a filter using chitosan for the purpose of adsorption of heavy metals and the like. However, since chitosan is not insolubilized in an acid solution, it is not suitable for recovering noble metals from an acid solution.

  Patent Document 2 describes fine particles containing a polymer having a structure in which chitosan molecules are cross-linked by a cross-linking group containing a coordinating group capable of coordinating to a noble metal ion. However, the production of the chitosan fine particles has a problem that various reagents and facilities are required.

  Patent Document 3 describes a cartridge filter that can selectively recover indium and retains a chitosan derivative that has been insolubilized in an acid solution.

  However, the present situation is that no adsorbent / separator that can perform high-speed processing and can recover a precious metal with high selectivity has not yet been provided.

JP-A-8-132037 JP 2008-95072 A JP 2011-47016 A

  The present invention provides a noble metal recovery cartridge filter using chitosan that enables efficient recovery of noble metal from an acid solution typified by industrial waste liquid, a method for producing the same, and a method for recovering noble metal using the same. This is the issue.

  As a result of examining the above problems, the present inventors have found that a noble metal can be efficiently recovered from an acid solution by holding a chitosan derivative subjected to insolubilization treatment with an acid on a filter, and completed the present invention.

（式中、Ｒ_１、Ｒ_２又はＲ_３は、それぞれ独立に、貴金属イオンに配位可能な配位基を含有する架橋基を形成しているか、もしくは水素であり、または、
Ｒ_２又はＲ_３は、それぞれ独立に、貴金属イオンに配位可能な配位基を含有する架橋基を形成しているか、もしくは水素であり、Ｒ_１は、貴金属イオンに配位可能な配位基であり、
ただしＲ_１、Ｒ_２及びＲ_３が同時に水素であることはなく、
該架橋基を形成するＲ_１、Ｒ_２又はＲ_３は、それぞれ独立に、同一又は異なるキトサン分子を構成する他のグルコサミンのＲ_１、Ｒ_２又はＲ_３と一緒になって貴金属イオンに配位可能な配位基を含有する架橋基を形成しており、
該架橋基の少なくとも１つは、異なるキトサン分子間に形成された架橋基である）
で表されるグルコサミン誘導体を含有することを特徴とする、上記カートリッジフィルター。
（２）架橋基が式（ＩＩ）：

（式中、Ｘ又はＹは、それぞれ独立に、Ｓ、ＮＲ又はＯであり、ただしＸ及びＹが同時にＯであることはなく、
Ｒは、水素又は貴金属イオンに配位可能な配位基であり、
ｍ又はｎは、それぞれ独立に、１以上の整数であり、
＊印は結合位置を示す）
で表される部分構造を含む、上記（１）に記載のカートリッジフィルター。
（３）カートリッジフィルター基材に、カートリッジフィルター基材に対し、５〜１００重量％のキトサン誘導体が保持されている、上記（１）又は（２）に記載のカートリッジフィルター。
（４）カートリッジフィルター基材が、コットン、レーヨン、パルプ、アセチルセルロース及びニトロセルロースからなる群より選択されるセルロース系繊維又はキトサン繊維によって形成されている、上記（１）〜（３）のいずれかに記載のカートリッジフィルター。
（５）セルロース系繊維又はキトサン繊維の繊維密度が０．１〜１．０ｇ／ｃｍ^３である、上記（４）に記載のカートリッジフィルター。
（６）上記（１）〜（５）のいずれかに記載のカートリッジフィルターの製造方法であって、
カートリッジフィルター基材をキトサン含有溶液に浸漬させてキトサンを保持させる工程、及び
カートリッジフィルター基材に保持されたキトサンに誘導体化処理を施す工程
を含むことを特徴とする、上記方法。
（７）キトサン含有溶液のキトサン濃度が１〜１０重量％である、上記（６）に記載の方法。
（８）キトサン含有溶液への浸漬処理を繰り返し行う、上記（６）又は（７）に記載の方法。
（９）貴金属を含有する酸性水溶液を上記（１）〜（５）のいずれかに記載のカートリッジフィルターに接触させて、貴金属をキトサン誘導体に吸着させる吸着工程；及び
貴金属を吸着させたキトサン誘導体を酸性水溶液、アルカリ水溶液、チオ尿素水溶液、塩化物水溶液、又はチオ尿素及び塩酸を含む水溶液に接触させて、貴金属を脱離させる脱離工程
を含む、貴金属の回収方法。 That is, the present invention includes the following inventions.
(1) A noble metal recovery cartridge filter comprising a porous core having at least one end opened and a cartridge filter base material wound around the porous core,
A chitosan derivative is held on the cartridge filter substrate;
The chitosan derivative is represented by the formula (I) as glucosamine constituting chitosan:

(Wherein R ₁ , R ₂ or R ₃ each independently form a bridging group containing a coordinating group capable of coordinating with a noble metal ion, or is hydrogen, or
R _{2 and} R ₃ each independently form a bridging group containing a coordinating group capable of coordinating to a noble metal ion or hydrogen, and R ₁ is a coordination capable of coordinating to a noble metal ion Group,
However, R ₁ , R ₂ and R ₃ are not simultaneously hydrogen,
R ₁ , R ₂ or R ₃ forming the bridging group independently coordinate to a noble metal ion together with other glucosamine R ₁ , R ₂ or R ₃ constituting the same or different chitosan molecule. Forming a bridging group containing possible coordinating groups,
At least one of the bridging groups is a bridging group formed between different chitosan molecules)
The cartridge filter comprising the glucosamine derivative represented by:
(2) The bridging group is represented by formula (II):

Wherein X or Y are each independently S, NR or O, provided that X and Y are not O at the same time,
R is a coordinating group capable of coordinating with hydrogen or a noble metal ion,
m or n each independently represents an integer of 1 or more,
(* Indicates the coupling position)
The cartridge filter according to (1) above, comprising a partial structure represented by:
(3) The cartridge filter according to the above (1) or (2), wherein the cartridge filter base material holds 5 to 100% by weight of the chitosan derivative relative to the cartridge filter base material.
(4) Any of the above (1) to (3), wherein the cartridge filter substrate is formed of a cellulosic fiber or chitosan fiber selected from the group consisting of cotton, rayon, pulp, acetylcellulose, and nitrocellulose. The cartridge filter described in.
(5) The cartridge filter according to the above (4), wherein the fiber density of the cellulosic fiber or chitosan fiber is 0.1 to 1.0 g / cm ³ .
(6) The method for producing a cartridge filter according to any one of (1) to (5) above,
The method as described above, comprising the steps of immersing the cartridge filter substrate in a chitosan-containing solution to retain the chitosan, and subjecting the chitosan retained on the cartridge filter substrate to a derivatization treatment.
(7) The method according to (6) above, wherein the chitosan-containing solution has a chitosan concentration of 1 to 10% by weight.
(8) The method according to (6) or (7) above, wherein the immersion treatment in the chitosan-containing solution is repeated.
(9) An adsorption step in which an acidic aqueous solution containing a noble metal is brought into contact with the cartridge filter according to any one of (1) to (5) to adsorb the noble metal on the chitosan derivative; and a chitosan derivative on which the noble metal is adsorbed A method for recovering a noble metal, comprising a desorption step of desorbing the noble metal by contacting with an acidic aqueous solution, an alkaline aqueous solution, a thiourea aqueous solution, a chloride aqueous solution, or an aqueous solution containing thiourea and hydrochloric acid.

  According to the cartridge filter of the present invention, the precious metal can be efficiently recovered from the acid solution. The cartridge filter of the present invention can be easily manufactured as compared with the conventional particulate filter. Further, the cartridge filter of the present invention has a good flow rate and is excellent in adsorptivity and desorption characteristics, so that the precious metal recovery process can be accelerated. Therefore, this invention is anticipated as a noble metal collection | recovery means from the acid solution represented by the industrial waste liquid.

FIG. 1 is a diagram illustrating a cartridge filter according to the first embodiment. FIG. 2 is a diagram illustrating a manufacturing flow of the cartridge filter according to the first embodiment. FIG. 3 is a view showing a production flow of the adsorbed fine particles of Comparative Example 1.

  The cartridge filter of the present invention is characterized in that the cartridge filter base material holds a chitosan derivative that has been insolubilized with respect to an acid. By using a chitosan derivative that has been insolubilized with respect to an acid, it becomes possible to recover the noble metal from the acid solution, and it is possible to recover the noble metal with high selectivity. Further, the cartridge filter of the present invention has a good flow rate and is excellent in adsorptivity and desorption characteristics, so that the precious metal recovery process can be accelerated. Further, the cartridge filter of the present invention can be easily manufactured as compared with the conventional particulate filter. Specifically, the chitosan can be held in the filter only by immersing the cartridge filter base material in the chitosan solution, so that the manufacturing process is markedly compared to the production of chitosan fine particles that require various reagents and equipment. It can be simplified and is advantageous for industrialization.

1. Noble Metal Recovery Cartridge Filter The cartridge filter substrate used for the cartridge filter of the present invention is wound around a porous core having at least one end opened. Examples of the winding shape include a yarn shape, a pleat shape, and a roll shape.

The cartridge filter substrate used in the cartridge filter of the present invention is preferably formed of cellulosic fibers or chitosan fibers selected from the group consisting of cotton, rayon, pulp, acetylcellulose and nitrocellulose, for example. When cellulosic fibers are used, the hydrophilic polymer chitosan can be retained with high affinity. Moreover, it is preferable that the fiber density of the cellulose fiber or chitosan fiber which forms this cartridge filter base material is 0.1-1.0 g / cm < ³ >. When the fiber density is 0.3 g / cm ³ , the variation in the amount of chitosan retained in the thickness direction of the cartridge filter is more preferable.

（式中、Ｒ_１、Ｒ_２又はＲ_３は、それぞれ独立に、貴金属イオンに配位可能な配位基を含有する架橋基を形成しているか、もしくは水素であり、または、
Ｒ_２又はＲ_３は、それぞれ独立に、貴金属イオンに配位可能な配位基を含有する架橋基を形成しているか、もしくは水素であり、Ｒ_１は、貴金属イオンに配位可能な配位基であり、
ただしＲ_１、Ｒ_２及びＲ_３が同時に水素であることはなく、
該架橋基を形成するＲ_１、Ｒ_２又はＲ_３は、それぞれ独立に、同一又は異なるキトサン分子を構成する他のグルコサミンのＲ_１、Ｒ_２又はＲ_３と一緒になって貴金属イオンに配位可能な配位基を含有する架橋基を形成しており、
該架橋基の少なくとも１つは、異なるキトサン分子間に形成された架橋基である）
で表されるグルコサミン誘導体を含有することを特徴とする。 In the cartridge filter of the present invention, a chitosan derivative is held on the cartridge filter substrate, and the chitosan derivative is represented by the formula (I) as glucosamine constituting chitosan:

(Wherein R ₁ , R ₂ or R ₃ each independently form a bridging group containing a coordinating group capable of coordinating with a noble metal ion, or is hydrogen, or
R _{2 and} R ₃ each independently form a bridging group containing a coordinating group capable of coordinating to a noble metal ion or hydrogen, and R ₁ is a coordination capable of coordinating to a noble metal ion Group,
However, R ₁ , R ₂ and R ₃ are not simultaneously hydrogen,
R ₁ , R ₂ or R ₃ forming the bridging group independently coordinate to a noble metal ion together with other glucosamine R ₁ , R ₂ or R ₃ constituting the same or different chitosan molecule. Forming a bridging group containing possible coordinating groups,
At least one of the bridging groups is a bridging group formed between different chitosan molecules)
It contains the glucosamine derivative represented by these.

Since the hydroxyl group on the 3-position carbon of glucosamine is less reactive than the amino group and the hydroxyl group on the 6-position carbon, the chitosan derivative used in the present invention contains a glucosamine derivative represented by the formula (I) Mainly include those in which R ₃ is hydrogen. In the chitosan derivative used in the present invention, in addition to the glucosamine derivative of the above formula (I) as a glucosamine constituting chitosan, normal glucosamine not having a crosslinking group, or all crosslinking groups are in the same molecule. A glucosamine derivative or the like having the same structure as the above formula (I) may be included except that it is formed between glucosamines.

  Examples of the “coordinating group capable of coordinating to the noble metal ion” include, but are not limited to, a coordinating group containing a sulfur atom, a nitrogen atom, and a combination thereof as a ligand. By using these coordination groups, noble metal ions can be adsorbed with high selectivity.

  It is preferable that two ligands are contained in one bridging group and the bridging group functions as a bidentate chelate ligand.

  The length of the bridging group is not particularly limited, but usually the number of atoms other than hydrogen is preferably 4-30, more preferably 4-20, and 6-12. Particularly preferred.

（式中、Ｘ又はＹは、それぞれ独立に、Ｓ、ＮＲ又はＯであり、ただしＸ及びＹが同時にＯであることはなく、
Ｒは、水素又は貴金属イオンに配位可能な配位基であり、
ｍ又はｎは、それぞれ独立に、１以上の整数であり、
＊印は結合位置を示す）
で表される部分構造を有するものであることが好ましい。式（II）において、ｎは２〜４の整数であることが好ましく、ｍは１〜４の整数であることが好ましい。 The bridging group is of formula (II):

Wherein X or Y are each independently S, NR or O, provided that X and Y are not O at the same time,
R is a coordinating group capable of coordinating with hydrogen or a noble metal ion,
m or n each independently represents an integer of 1 or more,
(* Indicates the coupling position)
It is preferable that it has the partial structure represented by these. In the formula (II), n is preferably an integer of 2 to 4, and m is preferably an integer of 1 to 4.

For example, as a specific coordinating _{groups, -NHCH 2 CH 2 NH -,} - HNCH 2 CH 2 NH 2, -SCH 2 CH 2 NH -, - SCH 2 CH 2 S -, - HNCH 2 CH 2 SH, - _{HNCH 2 CH 2 S -, -} SCH 2 CH 2 SCH 2 CH 2 NHCH 2 CH 2 NH -, - (NHCH 2 CH 2 NH) m -, - (NHCH 2 CH 2 S) m -, - (SCH 2 CH ₂ S) m-, or _{even, - (NH- (CH 2)} n-NH) m -, - (NH- (CH 2) n-S) m -, - (S- (CH 2) n-S _{) m -, - OCH 2 CH} 2 NH -, - OCH 2 CH 2 NH 2, -SCH 2 CH 2 O -, - OCH 2 CH 2 SH, -HNCH 2 CH 2 O -, - SCH 2 CH 2 SCH 2 CH ₂ NHCH ₂ CH ₂ O-, _{(OCH 2 CH 2 NH) m} -, - (NHCH 2 CH 2 S) m -, - (SCH 2 CH 2 S) m-, or _{even, - (NH- (CH 2)} n-NH) m-, _{- (NH- (CH 2) n} -S) m -, - (S- (CH 2) n-S) m -, - (O- (CH 2) n-NH) m -, - (O- ( _{CH 2) n-S) m} -,> NCH 2 CH 2 n <, - SCH 2 CH 2 n <, - OCH 2 CH 2 n <,> N- (CH 2) n-n <, - S- ( CH ₂ ) n—N <, —O— (CH ₂ ) n—N <, a pyridine ring, and a pyridine derivative (n or m is as defined above for formula (II)).

  The chitosan derivative is, for example, converted into a reactive group from the amino group of glucosamine, the hydroxyl group on the 6-position carbon, and / or the hydroxyl group on the 3-position carbon constituting the chitosan using a crosslinking agent, and the chitosan after the conversion And a compound having a coordination group capable of coordinating with a noble metal ion and having at least two functional groups capable of binding to the reactive group is reacted to crosslink between chitosan molecules. Examples of the crosslinking agent include, but are not limited to, epichlorohydrin, diepoxy alkane, diepoxy alkene, dialdehydes (glutaraldehyde, etc.), diisocyanates (toluene diisocyanate, etc.), or methylene bisacrylamide. It is preferable to select from a crosslinking agent having a bifunctional group, and it is more preferable to use epichlorohydrin.

For example, epichlorohydrin is used to convert the amino group and hydroxyl group of glucosamine to the reactive groups 2,3-epoxypropylamino group and 2,3-epoxypropyloxyl group, and then bond to the reactive group Ethylenediamine having two —NH ₂ groups that are possible functional groups and a nitrogen atom that is a ligand capable of coordinating to a noble metal ion is added and reacted to crosslink between the chitosan molecules. The chitosan derivative thus obtained may also have a form in which N and O of glucosamine are cross-linked. There may also be a form in which one end of the bridging group is bonded to O on the 3-position carbon and the other end is bonded to the amino group of another glucosamine, O on the 6-position carbon, or O on the 3-position carbon.

  The chitosan derivative is held in the cartridge filter base material in an amount of 5 to 100% by weight, preferably 10 to 30% by weight, based on the cartridge filter base material. A larger amount of chitosan derivative is preferred in that a large amount of noble metal can be adsorbed and the noble metal can be efficiently recovered.

2. Method for Producing Noble Metal Recovery Cartridge Filter The method for producing a cartridge filter of the present invention comprises a step of immersing a cartridge filter base material in a chitosan-containing solution to retain chitosan, and a derivatization treatment on chitosan retained on the cartridge filter base material. Including a step of applying. According to the production method of the present invention, it becomes possible to produce a noble metal recovery cartridge filter in which a chitosan derivative is held on a cartridge filter base material without going through complicated steps. In addition, when the cartridge filter base material is formed of chitosan fibers, the step of holding chitosan can be omitted.

2-1. Holding Chitosan to Cartridge Filter Substrate As the chitosan-containing solution for immersing the cartridge filter substrate, an acidic aqueous solution containing chitosan in a dissolved state can be used. As the acid contained in the acidic aqueous solution, it is preferable to use inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as acetic acid, lactic acid, glutamic acid, formic acid and adipic acid. The acid concentration is preferably 0.1 to 1M. Moreover, it is preferable that the density | concentration of chitosan is 1 to 10 weight%, and it is especially preferable that it is 3 to 6 weight%. When the chitosan concentration is less than 1% by weight, the amount of chitosan retained on the cartridge filter substrate is decreased, and as a result, the amount of precious metal recovered is undesirably reduced. On the other hand, when the chitosan concentration exceeds 10% by weight, the viscosity of the solution becomes high, and as a result, the fixing rate to the cartridge filter base material is unfavorable.

  By immersing the cartridge filter base material in the chitosan-containing solution, chitosan can be permeated into the cartridge filter base material. The immersion temperature is preferably 10 to 40 ° C, particularly preferably 20 to 30 ° C, and the immersion time is preferably 0.5 to 5 hours. Thereafter, the cartridge filter base material taken out from the acidic aqueous solution is immersed in an alkaline aqueous solution, and washed with water and dried appropriately, whereby a cartridge filter base material holding chitosan is obtained. As the alkali contained in the alkaline aqueous solution, sodium hydroxide, potassium hydroxide or the like is preferably used. The alkali concentration is preferably 0.1 to 1.0M. The immersion temperature is preferably 10 to 40 ° C, particularly preferably 20 to 30 ° C, and the immersion time is preferably 6 to 12 hours. The holding amount of chitosan held on the cartridge filter base material is calculated by measuring the dry weight of the cartridge filter base material before and after the dipping treatment and taking the difference as the holding amount of the chitosan.

  By repeating the above treatment steps 1 to 10 times, preferably 2 to 4 times, the retention amount can be increased without redissolving chitosan in the chitosan solution.

2-2. Chitosan derivatization treatment The derivatization treatment is applied to the chitosan held on the cartridge filter substrate. Thereby, it is possible to obtain a cartridge filter in which the chitosan derivative that has not been dissolved in an acidic solution, that is, subjected to insolubilization treatment, is retained.

  First, the cartridge filter base material holding chitosan by the above method is immersed in an aqueous solution containing a water-miscible solvent in advance. The water-miscible solvent is preferably ethanol, methanol, isopropyl alcohol, DMF, or DMSO, and preferably contains 30 to 100% by volume of the water-miscible solvent. More preferably, a 40% by volume ethanol aqueous solution is used. Moreover, it is preferable that the aqueous solution containing a water miscible solvent is room temperature-60 degreeC, More preferably, it is 20-30 degreeC.

  A cartridge filter substrate is impregnated by adding a crosslinking agent to the aqueous solution. The addition amount of the cross-linking agent is preferably 1 to 15 equivalents in terms of molar ratio with respect to the glucosamine (molecular weight 161) unit that is a constituent unit of chitosan held on the cartridge filter substrate, and is preferably 3 to 10 equivalents. It is more preferable. The immersion temperature is preferably room temperature to 60 ° C., and the immersion time is preferably 1 to 24 hours. Next, after adding a base, a compound containing a coordinating group capable of coordinating to the noble metal ion, such as ethylenediamine, is added, and the cartridge filter substrate is subsequently immersed in the aqueous solution. The base is preferably sodium hydroxide, potassium hydroxide, pyridine, triethylamine or the like, and more preferably sodium hydroxide. The addition amount of the base is preferably 1 to 10 equivalents and preferably 2 to 6 equivalents with respect to the glucosamine (molecular weight 161) unit that is a constituent unit of chitosan held on the cartridge filter substrate. Is more preferable. The addition amount of the compound containing a coordinating group capable of coordinating with the noble metal ion is 1 to 10 equivalents in terms of molar ratio with respect to the glucosamine (molecular weight 161) unit which is a constituent unit of chitosan held on the cartridge filter substrate. It is preferable to set it as 1 to 5 equivalents. The immersion temperature is preferably room temperature to 60 ° C., and the immersion time is preferably 2 to 24 hours. Thereafter, if necessary, the cartridge filter substrate is immersed in an acidic aqueous solution.

  Thereafter, the cartridge filter base material is taken out, washed with water and dried appropriately, whereby a cartridge filter holding the chitosan derivative can be obtained.

  By insolubilizing the chitosan held on the cartridge filter base material by the above method, it becomes possible to efficiently recover the noble metal from the acidic solution.

3. Noble metal recovery method The noble metal recovery method of the present invention comprises an adsorption step in which an acidic aqueous solution containing a noble metal is brought into contact with the cartridge filter to adsorb the noble metal to the chitosan derivative; A desorption step of desorbing a noble metal by contacting with an aqueous alkali solution, an aqueous thiourea solution, an aqueous chloride solution, or an aqueous solution containing thiourea and hydrochloric acid is included. By using the cartridge filter in the recovery method of the present invention, the flow rate in each step can be increased, and the processing time can be shortened. Each process which comprises the collection | recovery method of this invention is demonstrated in detail below.

3-1. Adsorption process The purpose of this process is to bring an acidic aqueous solution containing a noble metal into contact with the cartridge filter so that the noble metal is adsorbed to the chitosan derivative held on the cartridge filter substrate.

  The metal concentration of the acidic aqueous solution containing a noble metal used in this step is preferably 10 to 500 ppm. By using an acidic aqueous solution containing a noble metal at the above concentration, it becomes possible to adsorb the noble metal to chitosan with a high adsorption rate.

  In the recovery method of the present invention, the acid concentration in the acidic aqueous solution containing the noble metal is not particularly limited, but is preferably 6M or less from the viewpoint of operability, and is 0.01 to 0.1M. More preferably. Examples of the acid used include hydrochloric acid, nitric acid and sulfuric acid, and hydrochloric acid is preferred.

  Moreover, the acidic aqueous solution containing a noble metal used in this step further includes, for example, other metal components such as iron, copper, aluminum, nickel, cobalt, and / or one or more other components such as a surfactant. You may go out. The concentration of the one or more other metal ions is preferably 1/10 or less of the noble metal concentration. Even in the case of an acidic aqueous solution containing a noble metal in which the above-mentioned metal component and / or other components coexist, it is possible to selectively recover only the noble metal by applying the recovery method of the present invention. It becomes.

  This step can be carried out by mounting the cartridge filter in a filter housing adapted to the shape of the cartridge filter and passing an acidic aqueous solution containing a noble metal from the liquid introduction part. The material and shape of the filter housing to be used are not particularly limited as long as a cartridge filter can be mounted. Various types of filter housings commonly used in the industry can be used. In consideration of the properties of the solution used, it is preferable to use a resin filter housing made of polypropylene, polyvinyl chloride, fluorine or the like having high acid resistance. By carrying out this process with the cartridge filter mounted in the filter housing, it can be separated from the processing solution by simply emptying the inside of the filter housing without taking out the cartridge filter after completion of the adsorption process. It becomes possible to perform the transition between processes easily and quickly.

The flow rate when the acidic aqueous solution containing a noble metal is passed through the cartridge filter can be appropriately set depending on the volume of the solution and the size and / or number of cartridge filters, but usually 130 to 520 h ⁻ The space velocity (SV) is ¹ , preferably 200 h ^{−1 to} 300 h ⁻¹ , more preferably 240 h ^{−1 to} 280 h ⁻¹ , and even more preferably 260 h ⁻¹ . Since such a flow rate is higher than that of the conventional recovery method using an ion exchange resin or the like, it is possible to adsorb the noble metal to the chitosan derivative in a short time compared to the conventional technology.

  By carrying out this step in the manner as described above, it is possible to reduce labor required for processing and shorten processing time.

3-2. Circulation Step The adsorption step described above may be performed by a circulation step in which an acidic aqueous solution containing a noble metal is brought into contact with the cartridge filter and the solution after contact is circulated through the cartridge filter.

  In this step, an acidic aqueous solution containing a noble metal is passed through the cartridge filter. Here, the solution after passing through the cartridge filter can be circulated very easily by guiding the solution again to the liquid introduction portion of the cartridge filter. In the case of such an embodiment, it is preferable that the flow rate for circulating the solution is the same as that in the adsorption step.

  In this step, the number of times of circulating the solution after contacting the cartridge filter can be arbitrarily set. It is preferable to carry out this step until the adsorption amount of the noble metal reaches a saturation value. Quantification of the amount of precious metal adsorbed is preferably carried out, for example, using an atomic absorption photometer or an ICP emission spectroscopic analyzer.

  By carrying out the circulation step in the manner as described above, the adsorption rate of the noble metal can be improved.

3-3. Desorption process The purpose of this process is to desorb the noble metal by bringing the chitosan derivative adsorbed with the noble metal into contact with an acidic aqueous solution, alkaline aqueous solution, thiourea aqueous solution, chloride aqueous solution, or aqueous solution containing thiourea and hydrochloric acid. And

  The acidic aqueous solution used in this step preferably contains an acid such as hydrochloric acid, sulfuric acid and nitric acid. The acidic aqueous solution preferably has higher acidity than the acidic aqueous solution containing the noble metal used in the adsorption step. Further, the acid concentration is preferably 2 to 12M, more preferably 3 to 6M from the viewpoints of desorption efficiency and operability. In particular, when hydrochloric acid is used, the above concentration is preferable. By using an acidic aqueous solution containing a suitable acid at the above concentration, it is possible to increase the desorption rate of the noble metal.

  The aqueous alkali solution used in this step preferably contains an alkali such as ammonia and sodium hydroxide. The alkali concentration is preferably from 0.1 to 3M, more preferably from 0.5 to 2M, from the viewpoint of desorption efficiency and operability.

  The concentration of the aqueous thiourea solution used in this step is preferably 0.1 to 3M, and more preferably 0.5 to 2M, from the viewpoint of desorption efficiency and operability.

  The aqueous chloride solution used in this step preferably contains chlorides such as sodium chloride and potassium chloride. The chloride concentration is preferably 1 to 5M, more preferably 2 to 4M, from the viewpoint of desorption efficiency and operability.

  The concentration of the aqueous solution containing thiourea and hydrochloric acid used in this step is preferably 0.1 to 3M as thiourea and 2 to 12M as hydrochloric acid from the viewpoint of elimination efficiency and operability. It is preferable that each is.

  This step is performed by, for example, passing an acidic aqueous solution, an alkaline aqueous solution, a thiourea aqueous solution, a chloride aqueous solution, or an aqueous solution containing thiourea and hydrochloric acid from the liquid introduction part of the filter housing equipped with the cartridge filter. The precious metal may be desorbed in the eluate from the filter. The cartridge filter is removed from the filter housing, and the cartridge filter is immersed in the acidic aqueous solution, alkaline aqueous solution, thiourea aqueous solution, chloride aqueous solution, or aqueous solution containing thiourea and hydrochloric acid to remove the noble metal. Also good.

  The cartridge filter after the desorption step can be used again in the recovery method of the present invention by performing appropriate water washing without requiring any special pretreatment, so that the processing cost can be reduced.

  By performing the desorption step in the manner as described above, the noble metal adsorbed on the chitosan derivative can be completely or almost completely desorbed from the chitosan derivative.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to these Examples.

Example 1. Manufacture of cartridge filter holding chitosan derivative (1) Adhesion of chitosan to cartridge filter base material Commercially available chitosan powder (Kimika Co., Ltd., Kimikachitosan F2P) is added to 0.5M acetic acid aqueous solution to 6% by weight. Dissolved to make a chitosan solution. In this solution, a cartridge filter having a cylindrical part length of 58 mm and an outer diameter of 61 mm wound around a cylindrical perforated core with a density of 0.3 g / cm ³ of a cotton thread as a base material was immersed at 25 ° C. for 3 hours.

  Subsequently, the cartridge filter was taken out and immersed in a 1.0 M aqueous sodium hydroxide solution for 6 hours. Thereafter, the cartridge filter was taken out, immersed and washed with pure water, and then dried to fix the chitosan to the cartridge filter substrate. This operation was repeated twice.

(2) Chitosan derivatization treatment The cartridge filter was immersed in a 40% by volume ethanol aqueous solution, 5 equivalents of epichlorohydrin was added to the amount of chitosan attached, and then immersed at 25 ° C for 1 hour. Thereafter, 4 equivalents of an aqueous sodium hydroxide solution was added to the amount of chitosan attached, 2.5 equivalents of ethylenediamine were added, and the mixture was subsequently immersed for 6 hours. Next, after immersing in a 2.0 M hydrochloric acid aqueous solution for 12 hours, washing was performed using pure water. Finally, the cartridge filter was dried to obtain a cartridge filter holding the derivatized chitosan.

  The production flow of the above (1) and (2) is shown in FIG. As shown in FIG. 2, it can be seen that the cartridge filter of the present invention can be manufactured by a simple processing process, which is advantageous in promoting industrialization.

Comparative Example 1 Production of Adsorbed Fine Particles Retaining Chitosan Derivative (1) Preparation of Chitosan Fine Particles 16.2 g of chitosan powder (manufactured by Kimika Co., Ltd., Kimikachitosan F2P) was dispersed in 245.7 g of pure water to obtain 8.1 g of adipic acid. Was added to prepare 270 mL of a 6 wt% chitosan solution. 5.4 g of surfactant Tween 60 was added thereto to make the Tween 60 concentration 2% by weight. On the other hand, 500 mL of a 2 wt% tetraglycerin condensed ricinoleate (TGCR) hexane solution was prepared, placed in a flask, and stirred at 20 ° C. and 250 rpm using a stirring blade. Hexane was emulsified in the chitosan solution by adding 50 mL of hexane to the chitosan solution and stirring the homogenizer at 17500 rpm for 10 minutes. This chitosan emulsion was added to the stirring 2 wt% TGCR hexane solution to prepare a final chitosan emulsion. This chitosan emulsion was directly stirred at 20 ° C. and 250 rpm for 2 hours.

  Next, 250 mL of a 2 wt% TGCR hexane solution was prepared. To this solution, 250 mL of 15 wt% sodium chloride solution was added, and stirred at 17500 rpm for 6 minutes using a homogenizer to prepare a high-concentration sodium chloride emulsion in which the sodium chloride solution was emulsified in a hexane solution. This emulsion was added to the chitosan emulsion stirred in the flask and stirred at 20 ° C. and 250 rpm for 12 hours. The chitosan component in the chitosan emulsion was concentrated.

  Subsequently, 100 mL of ethanol was added to the mixture, and after stirring for 30 minutes, filtration was performed to prepare chitosan fine particles. Then, in order to remove TGCR adhering to chitosan fine particles, it was washed with ethanol. Finally, in order to regenerate into chitosan, the mixture was stirred with a 0.5 M NaOH methanol solution for 2 hours, then washed with ethanol and pure water, and dried to obtain chitosan fine particles.

(2) Chitosan derivatization treatment The chitosan fine particles were immersed in a 40% by volume ethanol aqueous solution, 5 equivalents of epichlorohydrin was added to the chitosan weight, and then immersed at 25 ° C for 1 hour. Thereafter, 4 equivalents of an aqueous sodium hydroxide solution was added to the amount of chitosan attached, 2.5 equivalents of ethylenediamine were added, and the mixture was subsequently immersed for 6 hours. Next, after immersing in a 2.0 M hydrochloric acid aqueous solution for 12 hours, washing was performed using pure water. Finally, the chitosan fine particles were dried to obtain derivatized chitosan fine particles.

  The production flow of the above (1) and (2) is shown in FIG. As shown in FIG. 3, in the case of a fine particle shape, the manufacturing method is complicated as compared with the cartridge filter.

  Example 1 and Comparative Example 1 were tested for flow rate and adsorption characteristics. In addition, Example 1 was tested for desorption characteristics.

After mounting the cartridge filter of Comparative Example 1 with a polypropylene housing on a polypropylene housing, the pressure loss when a 0.1 M aqueous hydrochloric acid solution was passed at 25 ° C. at a flow rate of SV = 260 / hr was confirmed.

  About the chitosan microparticles | fine-particles of the comparative example 1, the flowability test was done similarly to the test performed about the said Example 1 using the column packed with chitosan microparticles | fine-particles.

  The results are shown in Table 1. From Table 1, it was found that the pressure loss of the cartridge filter of Example 1 was 0.01 MPa or less, lower than the pressure loss of chitosan fine particles, and excellent in flowability.

Comparison of adsorption characteristics After mounting the cartridge filter of Example 1 on a polypropylene housing, 2.5 L of a test solution containing 100 ppm of palladium and platinum in a 0.1 M hydrochloric acid aqueous solution was prepared, and SV = 260 / Circulation was conducted at a flow rate of hr.

Each metal in the solution was measured with an atomic absorption photometer or an ICP emission spectrophotometer by collecting a certain amount of a measurement sample from the circulating test solution. The adsorption rate of each metal was calculated using the following formula.
Adsorption rate (%) = {(metal concentration of starting test solution−metal concentration of aging test solution) / metal concentration of starting test solution} × 100

  Using the column packed with chitosan fine particles of Comparative Example 1, an adsorption test was performed in the same manner as the test performed for Example 1 above. Here, the test liquid amount and flow rate with respect to the packed amount in the column were treated in the same manner.

  The results are shown in Table 2. From Table 2, in the case of the cartridge filter of Example 1, both palladium and platinum metals reached an adsorption rate of 80% or more 0.5 hours after the start of treatment. In contrast, in the case of the chitosan fine particles of Comparative Example 1, the time to reach an adsorption rate of 80% or more is 1 hour, and the cartridge filter of Example 1 has a shorter processing time than the chitosan fine particles of Comparative Example 1, and the adsorption characteristics. It was found to be excellent.

Desorption characteristics Palladium and platinum were adsorbed on the cartridge filter of Example 1 using a test solution containing 100 ppm of palladium and platinum in a 0.1 M hydrochloric acid aqueous solution (same test solution as in the above adsorption test). I let you. After the adsorption treatment, a 6.0 M hydrochloric acid aqueous solution was circulated through the cartridge filter at a flow rate of SV = 260 / hr as in the adsorption test. Table 3 shows the results after 6 hours.

  As shown in Table 3, it was found that the adsorbed palladium and platinum can be easily desorbed by circulating the liquid at a flow rate of SV = 260 / hr as in the adsorption test.

1: Core 2: Base material

Claims (9)

A noble metal recovery cartridge filter comprising a porous core having at least one open end and a cartridge filter substrate wound around the porous core,
A chitosan derivative is held on the cartridge filter substrate;
The chitosan derivative is represented by the formula (I) as glucosamine constituting chitosan:

(Wherein R ₁ , R ₂ or R ₃ each independently form a bridging group containing a coordinating group capable of coordinating with a noble metal ion, or is hydrogen, or
R _{2 and} R ₃ each independently form a bridging group containing a coordinating group capable of coordinating to a noble metal ion or hydrogen, and R ₁ is a coordination capable of coordinating to a noble metal ion Group,
However, R ₁ , R ₂ and R ₃ are not simultaneously hydrogen,
R ₁ , R ₂ or R ₃ forming the bridging group independently coordinate to a noble metal ion together with other glucosamine R ₁ , R ₂ or R ₃ constituting the same or different chitosan molecule. Forming a bridging group containing possible coordinating groups,
At least one of the bridging groups is a bridging group formed between different chitosan molecules)
The cartridge filter comprising the glucosamine derivative represented by: The bridging group is of formula (II):

Wherein X or Y are each independently S, NR or O, provided that X and Y are not O at the same time,
R is a coordinating group capable of coordinating with hydrogen or a noble metal ion,
m or n each independently represents an integer of 1 or more,
(* Indicates the coupling position)
The cartridge filter of Claim 1 containing the partial structure represented by these.   The cartridge filter according to claim 1 or 2, wherein the cartridge filter base material holds 5 to 100% by weight of the chitosan derivative relative to the cartridge filter base material.   The cartridge according to any one of claims 1 to 3, wherein the cartridge filter substrate is formed of cellulosic fibers or chitosan fibers selected from the group consisting of cotton, rayon, pulp, acetylcellulose, and nitrocellulose. filter. The cartridge filter according to claim 4, wherein the fiber density of the cellulosic fiber or chitosan fiber is 0.1 to 1.0 g / cm ³ . It is a manufacturing method of the cartridge filter according to any one of claims 1 to 5,
The method as described above, comprising the steps of immersing the cartridge filter substrate in a chitosan-containing solution to retain the chitosan, and subjecting the chitosan retained on the cartridge filter substrate to a derivatization treatment.   The method according to claim 6, wherein the chitosan-containing solution has a chitosan concentration of 1 to 10% by weight.   The method according to claim 6 or 7, wherein the immersion treatment in the chitosan-containing solution is repeated. An adsorption step in which an acidic aqueous solution containing a noble metal is brought into contact with the cartridge filter according to any one of claims 1 to 5 to adsorb the noble metal to the chitosan derivative; and the chitosan derivative adsorbing the noble metal adsorbed in the acidic aqueous solution, alkali A method for recovering a noble metal, comprising a desorption step of desorbing the noble metal by contacting with an aqueous solution, an aqueous thiourea solution, an aqueous chloride solution, or an aqueous solution containing thiourea and hydrochloric acid.

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