JPWO2019188708A1 - Platinum group element recovery method - Google Patents

Platinum group element recovery method Download PDF

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JPWO2019188708A1
JPWO2019188708A1 JP2020510806A JP2020510806A JPWO2019188708A1 JP WO2019188708 A1 JPWO2019188708 A1 JP WO2019188708A1 JP 2020510806 A JP2020510806 A JP 2020510806A JP 2020510806 A JP2020510806 A JP 2020510806A JP WO2019188708 A1 JPWO2019188708 A1 JP WO2019188708A1
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platinum group
water
group element
soluble polymer
hydrochloric acid
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JP7182222B2 (en
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一法 古川
一法 古川
章人 中井
章人 中井
英孝 川喜田
英孝 川喜田
重蔵 小山田
重蔵 小山田
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Zeon Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
    • C22B3/24—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition by adsorption on solid substances, e.g. by extraction with solid resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

白金族元素が吸着した水溶性高分子から白金族元素を回収する方法であって、０．２５〜３１．５０重量％の塩酸を含有する塩酸水溶液を準備する準備工程と、前記準備工程において準備した塩酸水溶液と、前記白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で、１．５時間以上混合する混合工程とを備え、前記混合工程における混合液中の、前記チオ尿素の含有割合を０．５〜２０．０重量％、前記白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％として混合を行う白金族元素の回収方法を提供する。A method for recovering a platinum group element from a water-soluble polymer adsorbed with a platinum group element, which is a preparation step for preparing an aqueous solution of hydrochloric acid containing 0.25 to 31.50% by weight of hydrochloric acid, and a preparation step for the preparation. The aqueous solution of hydrochloric acid and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea for 1.5 hours or more, and the thiourea in the mixed solution in the mixing step is provided. Provided is a method for recovering a platinum group element by mixing, with the content ratio of the platinum group element being 0.5 to 20.0% by weight and the content ratio of the water-soluble polymer adsorbed by the platinum group element being 16 to 72% by weight.

Description

本発明は、白金族元素が吸着した水溶性高分子から、白金族元素を回収する方法に関する。 The present invention relates to a method for recovering a platinum group element from a water-soluble polymer adsorbed by the platinum group element.

従来から、ニトリルゴム（アクリロニトリル−ブタジエン共重合ゴム）は、耐油性、機械的特性、耐薬品性等を活かして、ホースやチューブなどの自動車用ゴム部品の材料として使用されており、また、ニトリルゴムのポリマー主鎖中の炭素−炭素二重結合を水素化した水素化ニトリルゴム（水素化アクリロニトリル−ブタジエン共重合ゴム）はさらに耐熱性に優れるため、ベルト、ホース、ダイアフラム等のゴム部品に使用されている。 Traditionally, nitrile rubber (acrylonitrile-butadiene copolymer rubber) has been used as a material for rubber parts for automobiles such as hoses and tubes by taking advantage of its oil resistance, mechanical properties, chemical resistance, etc., and nitrile. Hydrogenated nitrile rubber (hydrogenated acrylonitrile-butadiene copolymer rubber), which is a hydrogenated carbon-carbon double bond in the polymer main chain of rubber, is used for rubber parts such as belts, hoses, and diaphragms because it has even better heat resistance. Has been done.

このような水素化ニトリルゴムは、たとえば、次の製造プロセスにより、製造される。すなわち、α，β−エチレン性不飽和ニトリル単量体や、共役ジエン単量体を含む単量体混合物を乳化重合し、乳化重合により得られるニトリルゴムのラテックスを凝固・乾燥し、次いで、凝固・乾燥により得られたニトリルゴムを水溶性有機溶媒に溶解することで、ニトリルゴムの水溶性有機溶媒溶液を得て、これに水素化触媒としての白金族元素含有触媒を添加し、水素化することにより製造される。 Such hydrogenated nitrile rubber is produced, for example, by the following production process. That is, an α, β-ethylenic unsaturated nitrile monomer or a monomer mixture containing a conjugated diene monomer is emulsion-polymerized, and the latex of the nitrile rubber obtained by the emulsion polymerization is coagulated and dried, and then coagulated. -By dissolving the nitrile rubber obtained by drying in a water-soluble organic solvent, a water-soluble organic solvent solution of nitrile rubber is obtained, and a platinum group element-containing catalyst as a hydrogenation catalyst is added thereto to hydrogenate the nitrile rubber. Manufactured by

一方で、このような製造方法により製造される水素化ニトリルゴムには、水素化触媒としての白金族元素含有触媒を用いるものであり、このような白金族元素含有触媒に含まれる白金族元素は高価であることから、その回収および再利用が望まれている。 On the other hand, the hydrogenated nitrile rubber produced by such a production method uses a platinum group element-containing catalyst as a hydrogenation catalyst, and the platinum group elements contained in such a platinum group element-containing catalyst are Due to its high price, its recovery and reuse are desired.

このような白金族元素を回収する技術として、たとえば、特許文献１や特許文献２には、アセチル化キトサン誘導体や、イミノジ酢酸またはジアルキルアミンが結合されてなるセルロースを吸着剤として用いるとともに、この吸着剤から白金族元素を脱離することで、白金族元素を回収する方法が提案されている。 As a technique for recovering such a platinum group element, for example, Patent Document 1 and Patent Document 2 use an acetylated chitosan derivative or cellulose to which iminodiacetic acid or dialkylamine is bound as an adsorbent, and adsorb this adsorbent. A method for recovering a platinum group element by desorbing the platinum group element from the agent has been proposed.

特開２００９−２４７９８１号公報Japanese Unexamined Patent Publication No. 2009-247981 特開２０１０−１７９２０８号公報Japanese Unexamined Patent Publication No. 2010-179208

しかしながら、上記特許文献１，２の技術においては、その実施例の開示からも明らかなように、塩酸水溶液中に含まれる白金族元素を、吸着剤に吸着させることを前提とした技術（吸着剤として、塩酸水溶液中で用いられるものを使用することを前提とする技術）であり、また、上記特許文献１，２の技術においては、吸着剤から白金族元素を脱離させた後、吸着剤を再利用した際に、白金族元素の吸着効率が低下してしまう（たとえば、特許文献１では再利用後の吸着効率が７０％程度、特許文献２では再利用後の吸着効率が９５％程度）という課題があった。さらには、上記特許文献１，２の技術においては、白金族元素を脱離させた吸着剤自体の回収効率について何ら記載されておらず、ましてや、白金族元素を脱離させた吸着剤自体の回収効率を向上させることについて、何らの知見が示されていないものであった。 However, in the techniques of Patent Documents 1 and 2, as is clear from the disclosure of the examples, the technique on the premise that the platinum group element contained in the hydrochloric acid aqueous solution is adsorbed on the adsorbent (adsorbent). (Technology premised on using the one used in an aqueous hydrochloric acid solution), and in the techniques of Patent Documents 1 and 2 above, after desorbing the platinum group element from the adsorbent, the adsorbent (For example, in Patent Document 1, the adsorption efficiency after reuse is about 70%, and in Patent Document 2, the adsorption efficiency after reuse is about 95%. ) Was a problem. Furthermore, in the techniques of Patent Documents 1 and 2, there is no description about the recovery efficiency of the adsorbent itself from which the platinum group element has been desorbed, much less the adsorbent itself from which the platinum group element has been desorbed. No findings have been shown regarding the improvement of recovery efficiency.

本発明は、このような実状に鑑みてなされたものであり、白金族元素が吸着した水溶性高分子から、高い回収率で白金族元素を回収でき、しかも、白金族元素を回収した後の水溶性高分子を、白金族元素を吸着させる用途に好適に再利用できる、白金族元素の回収方法を提供することを目的とする。 The present invention has been made in view of such an actual situation, and the platinum group element can be recovered from the water-soluble polymer adsorbed by the platinum group element with a high recovery rate, and after the platinum group element is recovered. It is an object of the present invention to provide a method for recovering a platinum group element, which can suitably reuse the water-soluble polymer for the purpose of adsorbing a platinum group element.

本発明者等は、白金族元素が吸着した水溶性高分子から白金族元素を回収する際に、所定の濃度の塩酸水溶液を予め準備し、このような塩酸水溶液と、白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で所定時間混合すること、さらには、この際における、混合液中の、チオ尿素の含有割合および白金族元素が吸着した水溶性高分子の含有割合を特定の範囲とすることにより、上記目的を達成できることを見出し、本発明を完成させるに至った。 When recovering a platinum group element from a water-soluble polymer on which a platinum group element is adsorbed, the present inventors prepared a hydrochloric acid aqueous solution having a predetermined concentration in advance, and such a hydrochloric acid aqueous solution and the platinum group element were adsorbed. Mixing the water-soluble polymer with the water-soluble polymer for a predetermined time in the presence of thiourea, and further, the content ratio of the thiourea and the content ratio of the water-soluble polymer adsorbed by the platinum group element in the mixed solution at this time. It has been found that the above object can be achieved by setting it within a specific range, and the present invention has been completed.

すなわち、本発明によれば、白金族元素が吸着した水溶性高分子から白金族元素を回収する方法であって、０．２５〜３１．５０重量％の塩酸を含有する塩酸水溶液を準備する準備工程と、前記準備工程において準備した前記塩酸水溶液と、前記白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で、１．５時間以上混合する混合工程とを備え、前記混合工程における混合液中の、前記チオ尿素の含有割合を０．５〜２０．０重量％、前記白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％として混合を行う白金族元素の回収方法が提供される。 That is, according to the present invention, a method for recovering a platinum group element from a water-soluble polymer adsorbed with a platinum group element, which is a preparation for preparing an aqueous hydrochloric acid solution containing 0.25 to 31.50% by weight of hydrochloric acid. The mixing step comprises a step of mixing the aqueous solution of hydrochloric acid prepared in the preparatory step and the water-soluble polymer adsorbed by the platinum group element in the presence of thiourea for 1.5 hours or more. The platinum group element to be mixed is mixed with the content ratio of the thiourea being 0.5 to 20.0% by weight and the content ratio of the water-soluble polymer adsorbed by the platinum group element being 16 to 72% by weight in the mixed solution. Recovery method is provided.

本発明の白金族元素の回収方法においては、前記混合工程における混合液中の、前記塩酸の含有割合を１．０〜１６．０重量％とすることが好ましい。
本発明の白金族元素の回収方法においては、前記水溶性高分子が、アミノ基含有（メタ）アクリレート系重合体であることが好ましい。
本発明の白金族元素の回収方法においては、前記アミノ基含有（メタ）アクリレート系重合体が、Ｎ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）の単独重合体、またはＮ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）を含む２種以上の単量体の共重合体であることが好ましい。
本発明の白金族元素の回収方法においては、前記白金族元素が、パラジウムであることが好ましい。
本発明の白金族元素の回収方法においては、前記白金族元素が、ニトリルゴムの水素化反応に用いた白金族元素含有触媒に由来の白金族元素であることが好ましい。
本発明の白金族元素の回収方法においては、前記混合工程が、前記準備工程において準備した前記塩酸水溶液と、前記チオ尿素とを予め混合することで、チオ尿素を含有する塩酸水溶液を得た後に、該チオ尿素を含有する塩酸水溶液に、前記白金族元素が吸着した水溶性高分子を添加して混合する工程であることが好ましい。
本発明の白金族元素の回収方法においては、前記チオ尿素を含有する塩酸水溶液中における、前記チオ尿素の含有割合が、１．０〜３５．０重量％であることが好ましい。
本発明の白金族元素の回収方法においては、前記混合工程において、前記準備工程において準備した前記塩酸水溶液に、前記白金族元素が吸着した水溶性高分子を添加する際に、前記白金族元素が吸着した水溶性高分子を固体の状態で添加することが好ましい。In the method for recovering a platinum group element of the present invention, the content ratio of hydrochloric acid in the mixed solution in the mixing step is preferably 1.0 to 16.0% by weight.
In the method for recovering a platinum group element of the present invention, it is preferable that the water-soluble polymer is an amino group-containing (meth) acrylate-based polymer.
In the method for recovering a platinum group element of the present invention, the amino group-containing (meth) acrylate-based polymer is a copolymer of N, N-dimethylaminoethyl methacrylate (DMAEMA) or N, N-dimethylaminoethyl methacrylate. It is preferably a copolymer of two or more kinds of monomers containing (DMAEMA).
In the method for recovering a platinum group element of the present invention, it is preferable that the platinum group element is palladium.
In the method for recovering a platinum group element of the present invention, it is preferable that the platinum group element is a platinum group element derived from the platinum group element-containing catalyst used in the hydrogenation reaction of nitrile rubber.
In the method for recovering a platinum group element of the present invention, in the mixing step, the hydrochloric acid aqueous solution prepared in the preparation step and the thiourea are mixed in advance to obtain a hydrochloric acid aqueous solution containing thiourea. It is preferable that the step is to add the water-soluble polymer adsorbed by the platinum group element to the hydrochloric acid aqueous solution containing the thiourea and mix them.
In the method for recovering a platinum group element of the present invention, the content ratio of the thiourea in the aqueous hydrochloric acid solution containing the thiourea is preferably 1.0 to 35.0% by weight.
In the method for recovering a platinum group element of the present invention, when the water-soluble polymer adsorbed by the platinum group element is added to the hydrochloric acid aqueous solution prepared in the preparation step in the mixing step, the platinum group element is used. It is preferable to add the adsorbed water-soluble polymer in a solid state.

本発明によれば、白金族元素が吸着した水溶性高分子から、高い回収率で白金族元素を回収でき、しかも、白金族元素を回収した後の水溶性高分子を、白金族元素を吸着させる用途に好適に再利用できる、白金族元素の回収方法を提供することができる。 According to the present invention, the platinum group element can be recovered from the water-soluble polymer to which the platinum group element is adsorbed with a high recovery rate, and the platinum group element is adsorbed on the water-soluble polymer after the platinum group element is recovered. It is possible to provide a method for recovering a platinum group element, which can be suitably reused for the purpose of making the element.

本発明の白金族元素の回収方法は、
白金族元素が吸着した水溶性高分子から白金族元素を回収する方法であって、
０．２５〜３１．５０重量％の塩酸を含有する塩酸水溶液を準備する準備工程と、
前記準備工程において準備した前記塩酸水溶液と、前記白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で、１．５時間以上混合する混合工程とを備え、
前記混合工程における混合液中の、前記チオ尿素の含有割合を０．５〜２０．０重量％、前記白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％として混合を行うものである。The method for recovering a platinum group element of the present invention is
A method of recovering a platinum group element from a water-soluble polymer adsorbed by the platinum group element.
A preparatory step for preparing an aqueous hydrochloric acid solution containing 0.25 to 31.50% by weight of hydrochloric acid, and
A mixing step of mixing the hydrochloric acid aqueous solution prepared in the preparation step with the water-soluble polymer adsorbed by the platinum group element in the presence of thiourea for 1.5 hours or more is provided.
Mixing is carried out with the content of the thiourea in the mixed solution in the mixing step being 0.5 to 20.0% by weight and the content of the water-soluble polymer adsorbed by the platinum group element being 16 to 72% by weight. It is a thing.

＜白金族元素＞
まず、本発明の回収方法において、回収の対象となる白金族元素について説明する。
本発明の回収方法において、回収の対象となる白金族元素としては、特に限定されないが、ニトリルゴムなどの共役ジエン系ゴム中に含まれる炭素−炭素二重結合を水素化することで、水素化ニトリルゴムなどの水素化共役ジエン系ゴムを得る際に用いられる、白金族元素含有触媒に由来の白金族元素などが挙げられる。このような共役ジエン系ゴムの水素化反応の一例として、ニトリルゴムの水素化反応を例示して、以下、説明する。<Platinum group element>
First, in the recovery method of the present invention, the platinum group element to be recovered will be described.
In the recovery method of the present invention, the platinum group element to be recovered is not particularly limited, but is hydrogenated by hydrogenating the carbon-carbon double bond contained in the conjugated diene rubber such as nitrile rubber. Examples thereof include platinum group elements derived from platinum group element-containing catalysts used for obtaining hydrogenated conjugated diene rubber such as nitrile rubber. As an example of such a hydrogenation reaction of a conjugated diene rubber, a hydrogenation reaction of a nitrile rubber will be illustrated below.

ニトリルゴムとしては、たとえば、α，β−エチレン性不飽和ニトリル単量体と、共役ジエン単量体とを少なくとも含む単量体混合物を共重合することにより得られる共重合体が挙げられる。α，β−エチレン性不飽和ニトリル単量体としては、ニトリル基を有するα，β−エチレン性不飽和化合物であれば特に限定されず、たとえば、アクリロニトリル；α−クロロアクリロニトリル、α−ブロモアクリロニトリルなどのα−ハロゲノアクリロニトリル；メタクリロニトリルなどのα−アルキルアクリロニトリル；などが挙げられる。また、共役ジエン単量体としては、１，３−ブタジエン、イソプレン、２，３−ジメチル−１，３−ブタジエン、１，３−ペンタジエン、クロロプレンなどの炭素数４〜６の共役ジエン単量体が挙げられる。 Examples of the nitrile rubber include a copolymer obtained by copolymerizing a monomer mixture containing at least an α, β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer. The α, β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group, and for example, acrylonitrile; α-chloroacrylonitrile, α-bromoacrylonitrile, etc. Α-halogenoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; and the like. Further, as the conjugated diene monomer, a conjugated diene monomer having 4 to 6 carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and chloroprene Can be mentioned.

ニトリルゴム中における、α，β−エチレン性不飽和ニトリル単量体単位の含有量は、全単量体単位に対して、好ましくは５〜６０重量％、より好ましくは１０〜５０重量％、さらに好ましくは１５〜５０重量％である。また、ニトリルゴム中における、共役ジエン単量体単位（水素化反応により、水素化されている部分も含む）の含有量は、全単量体単位に対して、好ましくは４０〜９５重量％、より好ましくは５０〜９０重量％、さらに好ましくは５０〜８５重量％である。 The content of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile rubber is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, and further, based on all the monomer units. It is preferably 15 to 50% by weight. The content of the conjugated diene monomer unit (including the portion hydrogenated by the hydrogenation reaction) in the nitrile rubber is preferably 40 to 95% by weight with respect to the total monomer unit. It is more preferably 50 to 90% by weight, still more preferably 50 to 85% by weight.

また、ニトリルゴムは、α，β−エチレン性不飽和ニトリル単量体および共役ジエン単量体に加えて、これらと共重合可能な他の単量体を共重合したものであってもよく、このような共重合可能な他の単量体としては、アクリル酸、メタクリル酸などのα，β−エチレン性不飽和モノカルボン酸単量体；α，β−エチレン性不飽和多価カルボン酸単量体；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチルなどのα，β−エチレン性不飽和モノカルボン酸エステル単量体；マレイン酸モノｎ−ブチル、フマル酸モノｎ−ブチルなどのα，β−エチレン性不飽和ジカルボン酸モノエステル単量体；エチレン；α−オレフィン単量体、芳香族ビニル単量体；フッ素含有ビニル単量体；共重合性老化防止剤；などが挙げられる。 Further, the nitrile rubber may be obtained by copolymerizing other monomers copolymerizable with the α, β-ethylene unsaturated nitrile monomer and the conjugated diene monomer. Other copolymerizable monomers include α, β-ethylenic unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; α, β-ethylenic unsaturated polyvalent carboxylic acid monopoly. Quantities: α such as methyl acrylate, ethyl acrylate, n-butyl acrylate, β-ethylenic unsaturated monocarboxylic acid ester monomer; α such as mono n-butyl maleate, mono n-butyl fumarate, etc. , Β-Ethylene unsaturated dicarboxylic acid monoester monomer; ethylene; α-olefin monomer, aromatic vinyl monomer; fluorine-containing vinyl monomer; copolymerizable antiaging agent; and the like.

ニトリルゴムの水素化反応は、通常、白金族元素含有触媒を用いて行われる。ニトリルゴムの水素化反応は、乳化重合により得られるニトリルゴムのラテックスに対し、ラテックス状態のまま行うこともできるし、あるいは、乳化重合により得られるニトリルゴムのラテックスを、凝固・乾燥して固形状のニトリルゴムを得て、得られたニトリルゴムを、水溶性有機溶媒に溶解して、重合体溶液の状態で行うこともできる。これらのなかでも、触媒活性等の観点より、得られたニトリルゴムを、水溶性有機溶媒に溶解して、重合体溶液の状態で行うことが好ましい。 The hydrogenation reaction of nitrile rubber is usually carried out using a platinum group element-containing catalyst. The hydrogenation reaction of the nitrile rubber can be carried out in a latex state with respect to the latex of the nitrile rubber obtained by the emulsion polymerization, or the latex of the nitrile rubber obtained by the emulsion polymerization is coagulated and dried into a solid state. The nitrile rubber of the above can be obtained, and the obtained nitrile rubber can be dissolved in a water-soluble organic solvent and carried out in the state of a polymer solution. Among these, from the viewpoint of catalytic activity and the like, it is preferable to dissolve the obtained nitrile rubber in a water-soluble organic solvent and carry out the process in the state of a polymer solution.

ニトリルゴムのラテックスの凝固・乾燥は、公知の方法により行えばよいが、凝固して得られるクラムと塩基性水溶液とを接触させる処理工程を設けることにより、得られるニトリルゴムをテトラヒドロフラン（ＴＨＦ）に溶解して測定される重合体溶液のｐＨが７を超えるように改質することが好ましい。ＴＨＦに溶解して測定される重合体溶液のｐＨは、好ましくは７．２〜１２、より好ましくは７．５〜１１．５、最も好ましくは８〜１１の範囲である。このクラムと塩基性水溶液との接触処理により、溶液系水素化を速やかに進行させることが可能となる。 The latex of nitrile rubber may be solidified and dried by a known method, but the obtained nitrile rubber is converted to tetrahydrofuran (THF) by providing a treatment step of bringing the crumb obtained by solidification into contact with a basic aqueous solution. It is preferable to modify the polymer solution to be dissolved and measured so that the pH of the polymer solution exceeds 7. The pH of the polymer solution measured by dissolving in THF is preferably in the range of 7.2-12, more preferably 7.5-11.5, and most preferably 8-11. By the contact treatment between the crumb and the basic aqueous solution, solution-based hydrogenation can be rapidly promoted.

水素化反応を行う際の重合体溶液中における、ニトリルゴムの濃度は、好ましくは１〜７０重量％、より好ましくは１〜４０重量％、特に好ましくは２〜２０重量％である。水溶性有機溶媒としては、たとえば、アセトン、メチルエチルケトン、ジエチルケトン、メチルイソプロピルケトンなどのケトン類；テトラヒドロフラン、ジオキサンなどのエーテル類；酢酸エチルなどのエステル類；などが挙げられる。これらの有機溶媒の中でもケトン類が好ましく用いられ、アセトンが特に好適に用いられる。 The concentration of the nitrile rubber in the polymer solution during the hydrogenation reaction is preferably 1 to 70% by weight, more preferably 1 to 40% by weight, and particularly preferably 2 to 20% by weight. Examples of the water-soluble organic solvent include ketones such as acetone, methyl ethyl ketone, diethyl ketone and methyl isopropyl ketone; ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate; and the like. Among these organic solvents, ketones are preferably used, and acetone is particularly preferably used.

水素化反応を行う際には、水素化触媒として、白金族元素含有触媒が用いられる。白金族元素含有触媒としては、白金族元素、すなわち、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウムまたは白金を含有する触媒であればよく、特に限定されないが、触媒活性や入手容易性の観点からパラジウム化合物、ロジウム化合物が好ましく、パラジウム化合物がより好ましい。また、２種以上の白金族元素化合物を併用してもよいが、その場合もパラジウム化合物を主たる触媒成分とすることが好ましい。 When the hydrogenation reaction is carried out, a platinum group element-containing catalyst is used as the hydrogenation catalyst. The platinum group element-containing catalyst may be a catalyst containing a platinum group element, that is, ruthenium, rhodium, palladium, osmium, iridium or platinum, and is not particularly limited, but is a palladium compound from the viewpoint of catalytic activity and availability. , Rhodium compounds are preferred, and palladium compounds are more preferred. Further, two or more kinds of platinum group element compounds may be used in combination, but even in that case, it is preferable to use a palladium compound as a main catalyst component.

パラジウム化合物は、通常、ＩＩ価またはＩＶ価のパラジウム化合物が用いられ、その形態は塩や錯塩である。 As the palladium compound, a divalent or IV-valent palladium compound is usually used, and the form thereof is a salt or a complex salt.

パラジウム化合物としては、例えば、酢酸パラジウム、シアン化パラジウム、フッ化パラジウム、塩化パラジウム、臭化パラジウム、ヨウ化パラジウム、硝酸パラジウム、硫酸パラジウム、酸化パラジウム、水酸化パラジウム、ジクロロ（シクロオクタジエン）パラジウム、ジクロロ（ノルボルナジエン）パラジウム、ジクロロビス（トリフェニルホスフィン）パラジウム、テトラクロロパラジウム酸ナトリウム、ヘキサクロロパラジウム酸アンモニウム、テトラシアノパラジウム酸カリウムなどが挙げられる。 Examples of the palladium compound include palladium acetate, palladium cyanide, palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium oxide, palladium hydroxide, and dichloro (cyclooctadien) palladium. Examples thereof include dichloro (norbornadiene) palladium, dichlorobis (triphenylphosphine) palladium, sodium tetrachloropalladium, ammonium hexachloropalladium, and potassium tetracyanopalladium.

これらのパラジウム化合物の中でも、酢酸パラジウム、硝酸パラジウム、硫酸パラジウム、塩化パラジウム、テトラクロロパラジウム酸ナトリウム、へキサクロロパラジウム酸アンモニウムが好ましく、酢酸パラジウム、硝酸パラジウムおよび塩化パラジウムがより好ましい。 Among these palladium compounds, palladium acetate, palladium nitrate, palladium sulfate, palladium chloride, sodium tetrachloropalladium, ammonium hexachloropalladium acid are preferable, and palladium acetate, palladium nitrate and palladium chloride are more preferable.

ロジウム化合物としては、たとえば、塩化ロジウム、臭化ロジウム、ヨウ化ロジウム、硝酸ロジウム、硫酸ロジウム、酢酸ロジウム、蟻酸ロジウム、プロピオン酸ロジウム、酪酸ロジウム、吉草酸ロジウム、ナフテン酸ロジウム、アセチルアセトン酸ロジウム、酸化ロジウム、三水酸化ロジウムなどが挙げられる。 Examples of the rhodium compound include rhodium chloride, rhodium bromide, rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate, rhodium naphthenate, rhodium acetylacetoneate, and oxidation. Examples include rhodium and rhodium trihydroxide.

白金族元素含有触媒としては、上述したパラジウム化合物やロジウム化合物をそのまま使用してもよいし、あるいは、上述したパラジウム化合物やロジウム化合物などの触媒成分を担体に担持させて、担持型触媒として使用してもよい。 As the platinum group element-containing catalyst, the above-mentioned palladium compound or rhodium compound may be used as it is, or the above-mentioned catalyst component such as the palladium compound or rhodium compound may be supported on a carrier and used as a supported catalyst. You may.

担持型触媒を形成するための担体としては、一般的に金属触媒の担体として用いられているものであればよいが、具体的には、炭素、ケイ素、アルミニウム、マグネシウムなどを含有する無機化合物が好ましく、その中でも、パラジウム化合物やロジウム化合物などの触媒成分の吸着効率がより高まるという観点より、担体の特性として、平均粒子径が１μｍ〜２００μｍ、比表面積が２００〜２０００ｍ２／ｇであるものを使用するのが好ましい。The carrier for forming the supported catalyst may be one that is generally used as a carrier for a metal catalyst, but specifically, an inorganic compound containing carbon, silicon, aluminum, magnesium, or the like is used. Among them, those having an average particle size of 1 μm to 200 μm and a specific surface area of 200 to 2000 m 2 / g are preferable from the viewpoint of further increasing the adsorption efficiency of catalyst components such as palladium compounds and rhodium compounds. It is preferable to use it.

このような担体は、活性炭、活性白土、タルク、クレー、アルミナゲル、シリカ、けいそう土、合成ゼオライトなど公知の触媒用担体の中から適宜に選択する。担体への触媒成分の担持方法としては、たとえば、含浸法、コーティング法、噴霧法、沈殿法などが挙げられる。触媒成分の担持量は、触媒と担体との合計量に対する触媒成分の割合で通常０．５〜８０重量％、好ましくは１〜５０重量％、より好ましくは２〜３０重量％である。触媒成分を担持した担体は、反応器の種類や反応形式などに応じて、たとえば、球状、円柱状、多角柱状、ハニカム状などに成形することができる。 Such a carrier is appropriately selected from known catalyst carriers such as activated carbon, activated clay, talc, clay, alumina gel, silica, diatomaceous earth, and synthetic zeolite. Examples of the method for supporting the catalyst component on the carrier include an impregnation method, a coating method, a spraying method, and a precipitation method. The amount of the catalyst component supported is usually 0.5 to 80% by weight, preferably 1 to 50% by weight, more preferably 2 to 30% by weight, as a ratio of the catalyst component to the total amount of the catalyst and the carrier. The carrier carrying the catalyst component can be formed into, for example, a spherical shape, a columnar shape, a polygonal columnar shape, a honeycomb shape, or the like, depending on the type of the reactor, the reaction type, and the like.

また、パラジウム化合物やロジウム化合物などの白金族元素の塩を担体に担持させずに、白金族元素含有触媒としてそのまま使用する場合においては、これらの化合物を安定させるための安定化剤を併用することが好ましい。安定化剤を、パラジウム化合物やロジウム化合物などの白金族元素含有触媒を溶解または分散させた媒体中に存在させることにより、ニトリルゴムを高水素添加率で水素化することができる。 In addition, when a salt of a platinum group element such as a palladium compound or a rhodium compound is not supported on a carrier and is used as it is as a platinum group element-containing catalyst, a stabilizer for stabilizing these compounds should be used in combination. Is preferable. Nitrile rubber can be hydrogenated at a high hydrogenation rate by allowing the stabilizer to be present in a medium in which a platinum group element-containing catalyst such as a palladium compound or a rhodium compound is dissolved or dispersed.

このような安定化剤としては、たとえば、ポリビニルピロリドン、ポリビニルアルコール、ポリビニルアセタール、ポリアルキルビニルエーテルなどの側鎖に極性基を有するビニル化合物の重合体；ポリアクリル酸のナトリウム、ポリアクリル酸カリウムなどのポリアクリル酸の金属塩；ポリエチレンオキサイド、ポリプロピレンオキサイド、エチレンオキサイド−プロピレンオキサイド共重合体などのポリエーテル；カルボキシメチルセルロース、ヒドロキシプロピルセルロースなどのセルロース誘導体；ゼラチン、アルブミンなどの天然高分子；などが挙げられる。これらの中でも、側鎖に極性基を有するビニル化合物の重合体、またはポリエーテルが好ましい。側鎖に極性基を有するビニル化合物の重合体の中では、ポリビニルピロリドン、ポリアルキルビニルエーテルが好ましく、ポリメチルビニルエーテルがより好ましい。 Examples of such stabilizers include polymers of vinyl compounds having a polar group on the side chain such as polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetal, and polyalkyl vinyl ether; sodium polyacrylic acid, potassium polyacrylate, and the like. Metallic salts of polyacrylic acid; polyethers such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymers; cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose; natural polymers such as gelatin and albumin; and the like. .. Among these, a polymer of a vinyl compound having a polar group in the side chain or a polyether is preferable. Among the polymers of vinyl compounds having a polar group in the side chain, polyvinylpyrrolidone and polyalkyl vinyl ether are preferable, and polymethyl vinyl ether is more preferable.

また、水素化反応に際しては、還元剤を併用してもよく、還元剤としては、ヒドラジン、ヒドラジン水和物、酢酸ヒドラジン、ヒドラジン硫酸塩、ヒドラジン塩酸塩等のヒドラジン類、またはヒドラジンを遊離する化合物などが挙げられる。 Further, in the hydrogenation reaction, a reducing agent may be used in combination, and the reducing agent is hydrazines such as hydrazine, hydrazine hydrate, hydrazine acetate, hydrazine sulfate, hydrazine hydrochloride, or a compound that liberates hydrazine. And so on.

水素化反応の温度は、通常０〜２００℃、好ましくは５〜１５０℃、より好ましくは１０〜１００℃である。水素化反応の温度を上記範囲とすることにより、副反応を抑えながら、反応速度を十分なものとすることができる。 The temperature of the hydrogenation reaction is usually 0 to 200 ° C, preferably 5 to 150 ° C, more preferably 10 to 100 ° C. By setting the temperature of the hydrogenation reaction within the above range, the reaction rate can be made sufficient while suppressing side reactions.

水素化反応を行う際における、水素の圧力は、通常、０．１〜２０ＭＰａであり、好ましくは０．１〜１５ＭＰａ、より好ましくは０．１〜１０ＭＰａである。反応時間は特に限定されないが、通常３０分〜５０時間である。なお、水素ガスは、先ず窒素などの不活性ガスで反応系を置換し、さらに水素で置換した後に加圧することが好ましい。 The pressure of hydrogen in carrying out the hydrogenation reaction is usually 0.1 to 20 MPa, preferably 0.1 to 15 MPa, and more preferably 0.1 to 10 MPa. The reaction time is not particularly limited, but is usually 30 minutes to 50 hours. It is preferable that the hydrogen gas is first replaced with an inert gas such as nitrogen, then replaced with hydrogen, and then pressurized.

そして、白金族元素含有触媒として、担持型触媒を使用した場合には、濾過や遠心分離などにより担持型触媒を分離することにより、水素化ニトリルゴムの水溶性有機溶媒溶液を得ることができる。 When a supported catalyst is used as the platinum group element-containing catalyst, a water-soluble organic solvent solution of hydrogenated nitrile rubber can be obtained by separating the supported catalyst by filtration, centrifugation or the like.

＜白金族元素が吸着した水溶性高分子＞
次いで、本発明の回収方法において用いる、白金族元素が吸着した水溶性高分子について説明する。
本発明の回収方法において用いる、白金族元素が吸着した水溶性高分子としては、特に限定されないが、たとえば、上記のような白金族元素含有触媒を使用してニトリルゴムの水素化を行った際に得られる、水素化ニトリルゴムの水溶性有機溶媒溶液から、白金族元素含有触媒に由来の白金族元素を、その回収や再利用のために、水溶性高分子に吸着させたものが好適に挙げられる。<Water-soluble polymer adsorbed with platinum group elements>
Next, the water-soluble polymer on which the platinum group element is adsorbed, which is used in the recovery method of the present invention, will be described.
The water-soluble polymer on which the platinum group element is adsorbed used in the recovery method of the present invention is not particularly limited, but for example, when hydrogenation of the nitrile rubber is performed using the platinum group element-containing catalyst as described above. Platinum group elements derived from a platinum group element-containing catalyst are preferably adsorbed on a water-soluble polymer for recovery and reuse from the water-soluble organic solvent solution of hydrogenated nitrile rubber obtained in Can be mentioned.

水素化ニトリルゴムから、白金族元素含有触媒に由来の白金族元素を、その回収や再利用のために、水溶性高分子に吸着させるための具体的な方法としては、たとえば、上記のような白金族元素含有触媒を使用してニトリルゴムの水素化を行った際に得られる、水素化ニトリルゴムの水溶性有機溶媒溶液に対し、水溶性高分子の水溶液を添加し、次いで、これを撹拌する方法が挙げられる。そして、このような方法によれば、水素化ニトリルゴムの水溶性有機溶媒溶液に、水溶性高分子の水溶液を添加し、これを撹拌することで、水素化ニトリルゴムの水溶性有機溶媒溶液に含まれる、白金族元素に水溶性高分子が配位し、白金族元素が水溶性高分子に取り込まれ、その一方で、水溶性高分子が、水溶性有機溶媒の影響により脱水和することで、水溶性高分子を、白金族元素が吸着した状態で析出させることができ、これにより白金族元素含有触媒に由来する白金族元素を、水素化ニトリルゴムから適切に分離させることが可能となる。また、この際においては、析出物として、白金族元素が吸着した水溶性高分子が得られることとなる。 Specific methods for adsorbing a platinum group element derived from a platinum group element-containing catalyst from a hydrogenated nitrile rubber to a water-soluble polymer for its recovery and reuse include, for example, the above. An aqueous solution of a water-soluble polymer is added to a water-soluble organic solvent solution of hydrogenated nitrile rubber obtained when hydrogenation of nitrile rubber is performed using a platinum group element-containing catalyst, and then this is stirred. There is a way to do it. Then, according to such a method, an aqueous solution of a water-soluble polymer is added to a water-soluble organic solvent solution of hydrogenated nitrile rubber, and the mixture is stirred to obtain a water-soluble organic solvent solution of hydrogenated nitrile rubber. A water-soluble polymer is coordinated with the contained platinum group element, and the platinum group element is incorporated into the water-soluble polymer, while the water-soluble polymer is dehydrogenated by the influence of the water-soluble organic solvent. , The water-soluble polymer can be precipitated in a state where the platinum group element is adsorbed, whereby the platinum group element derived from the platinum group element-containing catalyst can be appropriately separated from the hydrogenated nitrile rubber. .. Further, in this case, a water-soluble polymer adsorbed with a platinum group element can be obtained as a precipitate.

本発明で用いる水溶性高分子としては、水溶性を有し、水に可溶な高分子であればよく、特に限定されない。このような水溶性高分子としては、アミノ基含有（メタ）アクリレート系重合体（「アミノ基含有メタクリレート系重合体および／またはアミノ基含有アクリレート系重合体」の意味。以下、同様。）、カルボキシキル基含有（メタ）アクリレート系重合体、スルホン酸基含有（メタ）アクリレート系重合体、リン酸基含有（メタ）アクリレート系重合体などの変性基含有（メタ）アクリレート系重合体；アルキルセルロース、ヒドロキシアルキルセルロース、アルキルヒドロキシアルキルセルロースなどのセルロース誘導体；などが挙げられるが、これらの中でも、白金族元素との親和性が高く、水素化ニトリルゴムからの白金族元素の分離効果がより高いという観点より、変性基含有（メタ）アクリレート系重合体が好ましく、アミノ基含有（メタ）アクリレート系重合体がより好ましい。また、水溶性高分子に白金族元素含有触媒に由来する白金族元素を取り込ませた後、水溶性高分子を適切に析出させるという観点より、水溶性高分子としては、電気的に中性な水溶性高分子（すなわち、カチオン化やアニオン化がされてない水溶性高分子）であることが好ましく、特に、電気的に中性なアミノ基含有（メタ）アクリレート系重合体（すなわち、カチオン化やアニオン化がされてないアミノ基含有（メタ）アクリレート系重合体）が特に好ましい。 The water-soluble polymer used in the present invention is not particularly limited as long as it is a water-soluble and water-soluble polymer. Examples of such a water-soluble polymer include an amino group-containing (meth) acrylate-based polymer (meaning “amino group-containing methacrylate-based polymer and / or amino group-containing acrylate-based polymer”; the same applies hereinafter) and carboxy. Modified group-containing (meth) acrylate-based polymers such as kill group-containing (meth) acrylate-based polymers, sulfonic acid group-containing (meth) acrylate-based polymers, and phosphate group-containing (meth) acrylate-based polymers; alkylcellulose, Examples thereof include cellulose derivatives such as hydroxyalkyl cellulose and alkyl hydroxyalkyl cellulose; among these, the viewpoint that the affinity with the platinum group element is high and the separation effect of the platinum group element from the hydride nitrile rubber is higher. More preferably, a modified group-containing (meth) acrylate-based polymer is preferable, and an amino group-containing (meth) acrylate-based polymer is more preferable. Further, from the viewpoint of appropriately precipitating the water-soluble polymer after incorporating the platinum-group element derived from the platinum-group element-containing catalyst into the water-soluble polymer, the water-soluble polymer is electrically neutral. Water-soluble polymers (ie, water-soluble polymers that have not been cationized or anionized) are preferred, and in particular, electrically neutral amino group-containing (meth) acrylate-based polymers (ie, cationized). And an amino group-containing (meth) acrylate-based polymer that has not been anionized) is particularly preferable.

アミノ基含有（メタ）アクリレート系重合体としては、（メタ）アクリル酸エステル単位を主成分とする重合体であって、少なくとも一部にアミノ基を含有する重合体であればよく、特に限定されない。アミノ基含有（メタ）アクリレート系重合体は、たとえば、アミノ基含有（メタ）アクリル酸エステル単量体の単独重合体、二種以上のアミノ基含有（メタ）アクリル酸エステル単量体の共重合体、一種以上のアミノ基含有（メタ）アクリル酸エステル単量体と、これと共重合可能な一種以上の単量体との共重合体などが挙げられる。 The amino group-containing (meth) acrylate-based polymer is not particularly limited as long as it is a polymer containing a (meth) acrylic acid ester unit as a main component and contains at least a part of an amino group. .. The amino group-containing (meth) acrylate-based polymer is, for example, a copolymer of an amino group-containing (meth) acrylic acid ester monomer and a copolymer of two or more amino group-containing (meth) acrylic acid ester monomers. Examples thereof include a copolymer of one or more amino group-containing (meth) acrylic acid ester monomers and one or more monomers copolymerizable therewith.

アミノ基含有（メタ）アクリル酸エステル単量体の具体例としては、Ｎ，Ｎ−ジメチルアミノエチルアクリレート（ＤＭＡＥＡ）、Ｎ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）、Ｎ，Ｎ−ジメチルアミノプロピルアクリレート、Ｎ，Ｎ−ジメチルアミノプロピルメタクリレート、Ｎ，Ｎ−ｔ−ブチルアミノエチルアクリレート、Ｎ，Ｎ−ｔ−ブチルアミノエチルメタクリレート、Ｎ，Ｎ−モノメチルアミノエチルアクリレート、Ｎ，Ｎ−モノメチルアミノエチルメタクリレート等のアミノアルキル（メタ）アクリレート；Ｎ，Ｎ−ジメチルアクリルアミド、Ｎ，Ｎ−ジメチルメタクリルアミド、Ｎ，Ｎ−ジエチルアクリルアミド、Ｎ，Ｎ−ジエチルメタクリルアミド、Ｎ，Ｎ−ジメチルアミノプロピルアクリルアミド、Ｎ，Ｎ−ジメチルアミノプロピルメタクリルアミド、Ｎ，Ｎ−ジメチルアミノエチルアクリルアミド、Ｎ，Ｎ−ジメチルアミノエチルメタクリルアミド、Ｎ−イソプロピルアクリルアミド等のＮ−アミノアルキル（メタ）アクリルアミド；などが挙げられる。アミノ基含有（メタ）アクリル酸エステル単量体は一種単独でも、複数種を併用してもよい。これらのなかでも、アミノアルキル（メタ）アクリレートが好ましく、Ｎ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）が特に好ましい。 Specific examples of the amino group-containing (meth) acrylic acid ester monomer include N, N-dimethylaminoethyl acrylate (DMAEA), N, N-dimethylaminoethyl methacrylate (DMAEMA), and N, N-dimethylaminopropyl acrylate. , N, N-dimethylaminopropyl methacrylate, N, N-t-butylaminoethyl acrylate, N, N-t-butylaminoethyl methacrylate, N, N-monomethylaminoethyl acrylate, N, N-monomethylaminoethyl methacrylate, etc. Aminoalkyl (meth) acrylates; N, N-dimethylacrylamide, N, N-dimethylmethacrylate, N, N-diethylacrylamide, N, N-diethylmethacrylate, N, N-dimethylaminopropylacrylamide, N, N -N-aminoalkyl (meth) acrylamides such as dimethylaminopropylmethacrylamide, N, N-dimethylaminoethylacrylamide, N, N-dimethylaminoethylmethacrylate, N-isopropylacrylamide; and the like. The amino group-containing (meth) acrylic acid ester monomer may be used alone or in combination of two or more. Among these, aminoalkyl (meth) acrylate is preferable, and N, N-dimethylaminoethyl methacrylate (DMAEMA) is particularly preferable.

また、共重合可能な単量体の具体例としては、アクリル酸、メタクリル酸、イタコン酸、マレイン酸、フマル酸、無水マレイン酸、無水イタコン酸、無水フマル酸等の不飽和カルボン酸；２−ヒドロキシエチルアクリレート、ヒドロキシプロピルアクリレート、４−ヒドロキシブチルアクリレート、２−ヒドロキシエチルメタクリレート、ヒドロキシプロピルメタクリレート、４−ヒドロキシブチルメタクリレート等の水酸基含有ビニル；スチレン、２−メチルスチレン、ｔ−ブチルスチレン、クロルスチレン、ビニルアニソール、ビニルナフタレン、ジビニルベンゼン等の芳香族ビニル；アクリルアミド、メタクリルアミド、Ｎ−メチロールメタクリルアミド、Ｎ−メチロールアクリルアミド、ジアセトンアクリルアミド、マレイン酸アミド等のアミド；酢酸ビニル、プロピオン酸ビニル等のビニルエステル；塩化ビニリデン、フッ化ビニリデン等のハロゲン化ビニリデン；塩化ビニル、ジビニルエーテル、メチルビニルケトン、Ｎ−ビニルアセトアミド、クロロプレン、エチレン、プロピレン、イソプレン、ブタジエン、ビニルピロリドン、２−メトキシエチルアクリレート、２−エトキシエチルアクリレート、グリシジルアクリレート、グリシジルメタアクリレート、アリルグリシジルエーテル、アクリロニトリル、メタアクリロニトリル、エチレングリコールジメタクリレート、ジエチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、ポリエチレングリコールジメタクリレート、ポリプロピレングリコールジメタクリレート、ネオペンチルグリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、１，６−ヘキサンジオールジメタクリレート、ネオペンチルグリコールジメタクリレート、ポリエチレングリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、トリプロピレングリコールジアクリレート、ポリプロピレングリコールジアクリレート、トリメチロールプロパントリメタクリレート、トリメチロールプロパントリアクリレート、テトラメチロールメタントリアクリレート、テトラメチロールメタンテトラアクリレート、アリルメタクリレート、アリルアクリレート、ジシクロペンテニルアクリレート、ジシクロペンテニルオキシエチルアクリレート、イソプロペニル−α，α−ジメチルベンジルイソシアネート、アリルメルカプタン等が挙げられる。共重合可能な単量体は一種単独でも、複数種を併用してもよい。 Specific examples of the copolymerizable monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride; Hydroxyl-containing vinyls such as hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate; styrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, Aromatic vinyls such as vinylanisole, vinylnaphthalene and divinylbenzene; amides such as acrylamide, methacrylicamide, N-methylolmethacrylicamide, N-methylolacrylamide, diacetoneacrylamide and maleic acid amide; vinyl such as vinyl acetate and vinyl propionate. Esters; vinylidene halides such as vinylidene chloride and vinylidene fluoride; vinyl chloride, divinyl ether, methyl vinyl ketone, N-vinylacetamide, chloroprene, ethylene, propylene, isoprene, butadiene, vinylpyrrolidone, 2-methoxyethyl acrylate, 2- Ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, metaacrylonitrile, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate. , 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate , Polypropylene glycol diacrylate, Trimethylol propanetrimethacrylate, Trimethylol propanetriacrylate, Tetramethylol methanetriacrylate, Tetramethylol methanetetraacrylate, Allyl methacrylate, Allyl acrylate, Dicyclopentenyl acrylate, Dicyclopentenyloxyethyl acrylate, Isopropenyl -Α, α-dimethylbenze Examples thereof include luisocyanate and allyl mercaptan. The copolymerizable monomer may be used alone or in combination of two or more.

アミノ基含有（メタ）アクリレート系重合体中における、アミノ基含有（メタ）アクリル酸エステル単量体単位の含有割合は、水素化ニトリルゴムからの白金族元素の分離効果をより高めるという観点より、好ましくは３０〜１００重量％、より好ましくは５０〜１００重量％、特に好ましくは７０〜１００重量％である。 The content ratio of the amino group-containing (meth) acrylic acid ester monomer unit in the amino group-containing (meth) acrylate-based polymer is from the viewpoint of further enhancing the separation effect of the platinum group element from the hydrogenated nitrile rubber. It is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, and particularly preferably 70 to 100% by weight.

本発明で用いる水溶性高分子の重量平均分子量（Ｍｗ）は、水素化ニトリルゴムからの白金族元素の分離効果をより高めるという観点より、好ましくは１，０００〜１，５００，０００、より好ましくは５，０００〜１，２００，０００、さらに好ましくは１０，０００〜１，０００，０００、さらにより好ましくは２０，０００〜１，０００，０００、さらに一層好ましくは１００，０００〜１，０００，０００、特に好ましくは３００，０００〜１，０００，０００、最も好ましくは６００，０００〜１，０００，０００である。水溶性高分子の重量平均分子量（Ｍｗ）は、ゲル・パーミエーション・クロマトグラフィー法を用いて、標準ポリスチレンあるいは標準ポリエチレングリコール換算にて求めることができる。 The weight average molecular weight (Mw) of the water-soluble polymer used in the present invention is preferably 1,000 to 1,500,000, more preferably 1,500,000 from the viewpoint of further enhancing the effect of separating platinum group elements from hydrogenated nitrile rubber. Is 5,000 to 1,200,000, more preferably 10,000 to 1,000,000, even more preferably 20,000 to 1,000,000, even more preferably 100,000 to 1,000, 000, particularly preferably 300,000 to 1,000,000, most preferably 600,000 to 1,000,000. The weight average molecular weight (Mw) of the water-soluble polymer can be determined in terms of standard polystyrene or standard polyethylene glycol by using a gel permeation chromatography method.

水素化ニトリルゴムの水溶性有機溶媒溶液に、水溶性高分子を水溶液の状態で添加する際における、水溶液中の水溶性高分子の濃度は、水素化ニトリルゴムからの白金族元素の分離をより効率的に行うという観点より、好ましくは１〜４０重量％、より好ましくは２〜３０重量％、さらに好ましくは５〜２０重量％である。 When a water-soluble polymer is added to a water-soluble organic solvent solution of hydrogenated nitrile rubber in the state of an aqueous solution, the concentration of the water-soluble polymer in the aqueous solution determines the separation of platinum group elements from the hydrogenated nitrile rubber. From the viewpoint of efficient operation, it is preferably 1 to 40% by weight, more preferably 2 to 30% by weight, and further preferably 5 to 20% by weight.

また、水素化ニトリルゴムの水溶性有機溶媒溶液に、水溶性高分子を水溶液の状態で添加する際における、水溶性高分子の水溶液の添加量は、水素化ニトリルゴムからの白金族元素の分離をより効率的に行うという観点より、水素化ニトリルゴム１００重量部に対する、水溶性高分子の添加量が０．１〜５０重量部となる量が好ましく、０．５〜４０重量部となる量がより好ましく、１〜３０重量部となる量がさらに好ましく、１〜５重量部となる量が特に好ましい。 Further, when the water-soluble polymer is added to the water-soluble organic solvent solution of the hydrogenated nitrile rubber in the state of an aqueous solution, the amount of the aqueous solution of the water-soluble polymer added is the separation of the platinum group element from the hydrogenated nitrile rubber. From the viewpoint of more efficiently performing the above, the amount of the water-soluble polymer added to 100 parts by weight of the hydrogenated nitrile rubber is preferably 0.1 to 50 parts by weight, preferably 0.5 to 40 parts by weight. Is more preferable, an amount of 1 to 30 parts by weight is further preferable, and an amount of 1 to 5 parts by weight is particularly preferable.

水素化ニトリルゴムの水溶性有機溶媒溶液に、水溶性高分子を水溶液の状態で添加して、撹拌を行う際における、攪拌方法としては、特に限定されないが、たとえば、攪拌機を用いた方法や振とう器を用いた方法などが挙げられる。また、撹拌を行う際における、攪拌の条件も、特に限定されず、攪拌温度は、好ましくは５〜５０℃、より好ましくは１０〜４０℃であり、また、攪拌速度は、好ましくは１〜５００ｒｐｍ、より好ましくは５〜１００ｒｐｍである。混合時間は１．５時間以上であり、好ましくは２時間以上、より好ましくは３時間以上であり、上限は特に限定されないが、２４時間以下であり、混合時間をこのような範囲とすることにより、水素化ニトリルゴムからの白金族元素の分離を、高い効率にて行うことができる。 The stirring method when adding a water-soluble polymer in an aqueous solution to a water-soluble organic solvent solution of hydrogenated nitrile rubber is not particularly limited, but for example, a method using a stirrer or shaking. Examples include a method using a solvent. Further, the stirring conditions at the time of stirring are not particularly limited, the stirring temperature is preferably 5 to 50 ° C., more preferably 10 to 40 ° C., and the stirring speed is preferably 1 to 500 rpm. , More preferably 5 to 100 rpm. The mixing time is 1.5 hours or more, preferably 2 hours or more, more preferably 3 hours or more, and the upper limit is not particularly limited, but is 24 hours or less, and by setting the mixing time in such a range. , Platinum group elements can be separated from hydrogenated nitrile rubber with high efficiency.

＜白金族元素が吸着した水溶性高分子からの白金族元素の回収＞
そして、本発明の白金族元素の回収方法は、上述した白金族元素が吸着した水溶性高分子から、白金族元素を回収する方法である。具体的には、本発明の白金族元素の回収方法においては、白金族元素が吸着した水溶性高分子と、塩酸水溶液とを、チオ尿素の存在下において、混合するものであり、これにより、白金族元素が吸着した水溶性高分子から、白金族元素を回収するものである。<Recovery of platinum group elements from water-soluble polymers adsorbed by platinum group elements>
The method for recovering a platinum group element of the present invention is a method for recovering a platinum group element from the water-soluble polymer adsorbed by the platinum group element described above. Specifically, in the method for recovering a platinum group element of the present invention, a water-soluble polymer adsorbed by the platinum group element and an aqueous hydrochloric acid solution are mixed in the presence of thiourea. The platinum group element is recovered from the water-soluble polymer adsorbed by the platinum group element.

ここで、本発明においては、このような塩酸およびチオ尿素を用いた白金族元素の回収方法において、予め、塩酸濃度を０．２５〜３１．５０重量％に調整した塩酸水溶液を準備し、このような濃度に調整された塩酸水溶液中に、白金族元素が吸着した水溶性高分子を添加するものである。特に、本発明者等が検討を行ったところ、白金族元素が吸着した水溶性高分子と、塩酸水溶液とを互いに混ぜ合わせる時点（すなわち、白金族元素が吸着した水溶性高分子と、塩酸水溶液とを接触させる時点）における、塩酸水溶液中における塩酸濃度が高すぎると、白金族元素を回収した後の水溶性高分子が劣化してしまい、これにより、白金族元素を吸着させる用途に再利用した際における、白金族元素の吸着率が低下してしまうという問題があることを見出したものである。 Here, in the present invention, in such a method for recovering platinum group elements using hydrochloric acid and thiourea, an aqueous hydrochloric acid solution having a hydrochloric acid concentration adjusted to 0.25 to 31.50% by weight is prepared in advance. A water-soluble polymer in which platinum group elements are adsorbed is added to an aqueous hydrochloric acid solution adjusted to such a concentration. In particular, as a result of studies by the present inventors, the time point at which the water-soluble polymer adsorbed by the platinum group element and the aqueous solution of hydrochloric acid are mixed with each other (that is, the water-soluble polymer adsorbed by the platinum group element and the aqueous solution of hydrochloric acid). If the concentration of hydrochloric acid in the aqueous solution of hydrochloric acid is too high at the time of contact with), the water-soluble polymer after recovering the platinum group element will deteriorate, and as a result, it will be reused for the purpose of adsorbing the platinum group element. It was found that there is a problem that the adsorption rate of platinum group elements is lowered at that time.

そして、本発明によれば、このような状況において、白金族元素が吸着した水溶性高分子と、塩酸水溶液とを互いに混ぜ合わせる時点（すなわち、白金族元素が吸着した水溶性高分子と、塩酸水溶液とが接触させる時点）における、塩酸水溶液の濃度を０．２５〜３１．５０重量％に制御することにより、このような問題を有効に解決できることを見出したものである。特に、本発明者等の知見によると、水素化反応後の水素化ニトリルゴムを水溶性有機溶媒溶液として得た場合には、水素化に用いた白金族元素含有触媒に由来の白金族元素の分離は、水溶性有機溶媒中で行われるため、酸性雰囲気とされることはなく、そのため、このような用途に用いられる水溶性高分子は、塩酸による影響を受けやすい傾向にあるものであることを見出したものであり、これに対し、本発明によれば、白金族元素が吸着した水溶性高分子と、塩酸水溶液とを互いに混ぜ合わせる時点（すなわち、白金族元素が吸着した水溶性高分子と、塩酸水溶液とが接触させる時点）における、塩酸水溶液の濃度を上記範囲に制御することにより、このような問題を有効に解決できることを見出したものである。そのため、本発明によれば、吸着剤として、水素化ニトリルゴムの水素化に用いた白金族元素含有触媒に由来の白金族元素の吸着に好適に用いられる水溶性高分子を用いた場合、とりわけ、吸着剤として、アミノ基含有（メタ）アクリレート系重合体を用いた場合に、このような塩酸水溶液とを互いに混ぜ合わせる時点（すなわち、白金族元素が吸着した水溶性高分子と、塩酸水溶液とが接触させる時点）における、塩酸水溶液の濃度の影響が大きくなる傾向にあるものであり、そのため、吸着剤として、水溶性高分子を用いた場合、とりわけ、アミノ基含有（メタ）アクリレート系重合体を用いた場合に、本発明の作用効果が顕著になるものである。 According to the present invention, in such a situation, when the water-soluble polymer adsorbed by the platinum group element and the aqueous hydrochloric acid solution are mixed with each other (that is, the water-soluble polymer adsorbed by the platinum group element and hydrochloric acid It has been found that such a problem can be effectively solved by controlling the concentration of the hydrochloric acid aqueous solution to 0.25 to 31.50% by weight at the time of contact with the aqueous solution). In particular, according to the findings of the present inventors, when the hydrogenated nitrile rubber after the hydrogenation reaction is obtained as a water-soluble organic solvent solution, the platinum group element derived from the platinum group element-containing catalyst used for hydrogenation Since the separation is carried out in a water-soluble organic solvent, it does not have an acidic atmosphere, and therefore the water-soluble polymer used for such applications tends to be easily affected by hydrochloric acid. On the other hand, according to the present invention, at the time when the water-soluble polymer adsorbed by the platinum group element and the aqueous hydrochloric acid solution are mixed with each other (that is, the water-soluble polymer adsorbed by the platinum group element). It has been found that such a problem can be effectively solved by controlling the concentration of the hydrochloric acid aqueous solution within the above range at the time of contact with the hydrochloric acid aqueous solution). Therefore, according to the present invention, especially when a water-soluble polymer preferably used for adsorbing a platinum group element derived from a platinum group element-containing catalyst used for hydrogenation of hydrogenated nitrile rubber is used as an adsorbent. When an amino group-containing (meth) acrylate-based polymer is used as the adsorbent, the time point at which such an aqueous solution of hydrochloric acid is mixed with each other (that is, the water-soluble polymer adsorbed by the platinum group element and the aqueous solution of hydrochloric acid Therefore, when a water-soluble polymer is used as the adsorbent, the influence of the concentration of the aqueous hydrochloric acid solution at the time of contact with the polymer tends to be large. When is used, the action and effect of the present invention become remarkable.

本発明の白金族元素の回収方法において、予め準備する塩酸水溶液中における、塩酸濃度は０．２５〜３１．５０重量％であり、好ましくは１０．０〜２０．０重量％、より好ましくは１４．０〜１７．５重量％である。塩酸水溶液中における、塩酸濃度が高すぎると、白金族元素を回収した後の水溶性高分子を、白金族元素を吸着させる用途に再利用した際における回収効率が低下してしまう。一方、塩酸水溶液中における、塩酸濃度が低すぎると、白金族元素が吸着した水溶性高分子からの、白金族元素の回収効率が低下してしまう。 In the method for recovering a platinum group element of the present invention, the hydrochloric acid concentration in the hydrochloric acid aqueous solution prepared in advance is 0.25 to 31.50% by weight, preferably 10.0 to 20.0% by weight, and more preferably 14. It is 0 to 17.5% by weight. If the hydrochloric acid concentration in the hydrochloric acid aqueous solution is too high, the recovery efficiency when the water-soluble polymer after recovering the platinum group element is reused for the purpose of adsorbing the platinum group element is lowered. On the other hand, if the hydrochloric acid concentration in the hydrochloric acid aqueous solution is too low, the recovery efficiency of the platinum group element from the water-soluble polymer adsorbed by the platinum group element is lowered.

なお、塩酸水溶液中に、白金族元素が吸着した水溶性高分子を添加する際には、白金族元素が吸着した水溶性高分子は、固体の状態で添加してもよいし、あるいは、水溶液の状態で添加してもよいが、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、混合液中における、塩酸濃度を制御し易いという観点より、白金族元素が吸着した水溶性高分子は、固体の状態で添加することが好ましい。なお、この際においては、水溶性高分子は、実質的に固体状態であるといえるものであればよく、若干量の水分（たとえば、１重量％以下程度の水分）が含まれていてもよい。 When a water-soluble polymer adsorbed with a platinum group element is added to an aqueous solution of hydrochloric acid, the water-soluble polymer adsorbed with the platinum group element may be added in a solid state, or may be added in an aqueous solution. However, when the aqueous solution of hydrochloric acid and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, it is easy to control the concentration of hydrochloric acid in the mixed solution. From the viewpoint, it is preferable to add the water-soluble polymer on which the platinum group element is adsorbed in a solid state. In this case, the water-soluble polymer may be a water-soluble polymer as long as it can be said to be in a substantially solid state, and may contain a small amount of water (for example, water of about 1% by weight or less). ..

また、本発明の白金族元素の回収方法においては、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合するものであるが、これらを混合している際における、混合液中における、チオ尿素の含有割合を０．５〜２０．０重量％とするものであり、好ましくは３．０〜１８．０重量％、より好ましくは５．０〜１７．０重量％である。混合液中における、チオ尿素の含有割合が少なすぎると、白金族元素が吸着した水溶性高分子からの、白金族元素の回収効率が低下してしまう。一方、チオ尿素の含有割合が多すぎると、水溶性高分子中に硫黄が取り込まれてしまい、水溶性高分子を吸着剤として再利用した際に、吸着の対象となる水素化ニトリルゴムなどの共役ジエン系ゴムに硫黄が混入し、これにより、乾燥工程の熱などにより架橋が進行してしまったり、最終的に得られる水素化ニトリルゴムなどの水素化共役ジエン系ゴムに意図しない硫黄が含まれることで、架橋の制御が困難となる場合がある。 Further, in the method for recovering a platinum group element of the present invention, an aqueous hydrochloric acid solution and a water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, and these are mixed. The content of thiourea in the mixed solution is 0.5 to 20.0% by weight, preferably 3.0 to 18.0% by weight, and more preferably 5.0 to 17. It is 0% by weight. If the content of thiourea in the mixed solution is too small, the recovery efficiency of the platinum group element from the water-soluble polymer adsorbed by the platinum group element will decrease. On the other hand, if the content of thiourea is too high, sulfur will be incorporated into the water-soluble polymer, and when the water-soluble polymer is reused as an adsorbent, hydrogenated nitrile rubber or the like to be adsorbed will be used. Sulfur is mixed into the conjugated diene rubber, which causes cross-linking to proceed due to the heat of the drying process, etc., and the finally obtained hydrogenated conjugated diene rubber such as hydrogenated nitrile rubber contains unintended sulfur. This may make it difficult to control the cross-linking.

なお、本発明の白金族元素の回収方法においては、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合するものであればよく、チオ尿素の添加時期としては、特に限定されないが、（１）塩酸水溶液中に、チオ尿素を予め添加しておき、チオ尿素を含有する塩酸水溶液に、白金族元素が吸着した水溶性高分子を添加して混合する方法、（２）塩酸水溶液に、白金族元素が吸着した水溶性高分子を添加する際に、チオ尿素をそのまま、あるいは水溶液の状態にて添加して混合する方法、（３）塩酸水溶液に、白金族元素が吸着した水溶性高分子を添加して混合を開始した後に、チオ尿素をそのまま、あるいは水溶液の状態にて添加して、混合を継続する方法、などが挙げられる。これらの中でも、操作性の観点より、上記（１）の方法が好ましい。この際における、チオ尿素を含有する塩酸水溶液中における、チオ尿素の含有割合は、特に限定されないが、好ましくは１．０〜３５．０重量％、より好ましくは２．０〜２５．０重量％、さらに好ましくは５．０〜１０．０重量％である。 In the method for recovering a platinum group element of the present invention, an aqueous hydrochloric acid solution and a water-soluble polymer adsorbed by the platinum group element may be mixed in the presence of thiourea, and the timing of adding thiourea may be sufficient. The method is not particularly limited, but (1) thiourea is added in advance to the hydrochloric acid aqueous solution, and the water-soluble polymer adsorbed by the platinum group element is added to the hydrochloric acid aqueous solution containing thiourea and mixed. Method, (2) When adding a water-soluble polymer in which platinum group elements are adsorbed to an aqueous hydrochloric acid solution, thiourea is added as it is or in the state of an aqueous solution and mixed. Examples thereof include a method in which a water-soluble polymer adsorbed with a platinum group element is added to start mixing, and then thiourea is added as it is or in an aqueous solution to continue mixing. Among these, the method (1) above is preferable from the viewpoint of operability. At this time, the content ratio of thiourea in the aqueous hydrochloric acid solution containing thiourea is not particularly limited, but is preferably 1.0 to 35.0% by weight, more preferably 2.0 to 25.0% by weight. , More preferably 5.0 to 10.0% by weight.

また、本発明の白金族元素の回収方法においては、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、混合液中における、白金族元素が吸着した水溶性高分子の含有割合を、１６〜７２重量％とするものであり、好ましくは２０〜６５重量％、より好ましくは２０〜５５重量％、さらに好ましくは３０〜５０重量％である。混合液中における、白金族元素が吸着した水溶性高分子の含有割合が少なすぎると、白金族元素を回収した後の水溶性高分子の回収率（すなわち、再利用に供することのできる水溶性高分子の割合）が低下してしまう。一方、混合液中における、白金族元素が吸着した水溶性高分子の含有割合が多すぎると、白金族元素が吸着した水溶性高分子からの、白金族元素の回収効率が低下してしまう。 Further, in the method for recovering a platinum group element of the present invention, a platinum group element in a mixed solution when an aqueous hydrochloric acid solution and a water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea. The content ratio of the water-soluble polymer adsorbed by the element is 16 to 72% by weight, preferably 20 to 65% by weight, more preferably 20 to 55% by weight, still more preferably 30 to 50% by weight. .. If the content of the water-soluble polymer adsorbed by the platinum group element in the mixed solution is too small, the recovery rate of the water-soluble polymer after the platinum group element is recovered (that is, the water-soluble polymer that can be reused). The ratio of high molecular weight) will decrease. On the other hand, if the content ratio of the water-soluble polymer adsorbed by the platinum group element is too large in the mixed solution, the recovery efficiency of the platinum group element from the water-soluble polymer adsorbed by the platinum group element is lowered.

なお、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、混合液中における塩酸濃度（すなわち、白金族元素が吸着した水溶性高分子およびチオ尿素を添加した後の混合液中における塩酸濃度）は、特に限定されないが、好ましくは１．０〜１６．０重量％であり、より好ましくは５．０〜１４．０重量％、さらに好ましくは６．０〜９．０重量％である。混合液中における塩酸濃度を上記範囲とすることにより、白金族元素が吸着した水溶性高分子からの、白金族元素の回収効率をより適切に高めるこができる。 When the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, the hydrochloric acid concentration in the mixed solution (that is, the water-soluble polymer adsorbed by the platinum group element and the water-soluble polymer and the water-soluble polymer adsorbed by the platinum group element. The hydrochloric acid concentration in the mixed solution after the addition of thiourea) is not particularly limited, but is preferably 1.0 to 16.0% by weight, more preferably 5.0 to 14.0% by weight, still more preferably. Is 6.0 to 9.0% by weight. By setting the hydrochloric acid concentration in the mixed solution within the above range, it is possible to more appropriately increase the recovery efficiency of the platinum group element from the water-soluble polymer adsorbed by the platinum group element.

また、本発明の白金族元素の回収方法において、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、混合時間は、１．５時間以上、好ましくは２時間以上、より好ましくは２〜４時間である。混合時間が短すぎると、白金族元素が吸着した水溶性高分子からの、白金族元素の回収効率が低下してしまう。一方、混合時間が長すぎると、プロセス全体のサイクルタイムが長くなり生産性が低下してしまう。 Further, in the method for recovering a platinum group element of the present invention, when the hydrochloric acid aqueous solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, the mixing time is 1.5 hours or more. It is preferably 2 hours or more, more preferably 2 to 4 hours. If the mixing time is too short, the recovery efficiency of the platinum group elements from the water-soluble polymer adsorbed by the platinum group elements will decrease. On the other hand, if the mixing time is too long, the cycle time of the entire process becomes long and the productivity decreases.

塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、混合温度は、特に限定されないが、好ましくは５〜９０℃、より好ましくは１０〜３０℃である。白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、これらの混合方法は、たとえば、攪拌機を用いた方法や振とう器を用いた方法などが挙げられる。 The mixing temperature at the time of mixing the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed with the platinum group element in the presence of thiourea is not particularly limited, but is preferably 5 to 90 ° C., more preferably 10 to 30 ° C. ℃. When mixing a water-soluble polymer adsorbed with a platinum group element in the presence of thiourea, examples of these mixing methods include a method using a stirrer and a method using a shaker.

そして、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合させた後、得られた混合液に、水溶性高分子に対して溶解性を示さない有機溶媒を添加することで、水溶性高分子を析出させ、ろ過などの方法により、混合液から水溶性高分子を分離させる。また、水溶性高分子から脱離した白金族元素については、焼却などにより、混合液から回収することできる。一方、析出させた水溶性高分子は、ニトリルゴムなどの共役ジエン系ゴム中に含まれる炭素−炭素二重結合を水素化する際に用いられる、白金族元素含有触媒に由来の白金族元素を吸着させる吸着剤として、再利用することができる。水溶性高分子に対して溶解性を示さない有機溶媒としては、特に限定されず、使用する水溶性高分子の種類に応じて選択すればよいが、たとえば、アセトン、メチルエチルケトン、ジエチルケトン、メチルイソプロピルケトンなどのケトン類；テトラヒドロフラン、ジオキサンなどのエーテル類；酢酸エチルなどのエステル類；などが挙げられ、これらの有機溶媒の中でもケトン類が好ましく用いられ、アセトンが特に好適に用いられる。 Then, the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, and then the obtained mixed solution is an organic substance that does not show solubility in the water-soluble polymer. By adding a solvent, the water-soluble polymer is precipitated, and the water-soluble polymer is separated from the mixed solution by a method such as filtration. Further, the platinum group element desorbed from the water-soluble polymer can be recovered from the mixed solution by incineration or the like. On the other hand, the precipitated water-soluble polymer contains a platinum group element derived from a platinum group element-containing catalyst used for hydrogenating a carbon-carbon double bond contained in a conjugated diene rubber such as nitrile rubber. It can be reused as an adsorbent to be adsorbed. The organic solvent that does not show solubility in the water-soluble polymer is not particularly limited and may be selected depending on the type of the water-soluble polymer used. For example, acetone, methyl ethyl ketone, diethyl ketone, and methyl isopropyl may be selected. Examples thereof include ketones such as ketones; ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate; and the like. Among these organic solvents, ketones are preferably used, and acetone is particularly preferably used.

特に、本発明の回収方法においては、上述した所定の濃度の塩酸水溶液を予め準備し、このような予め準備した塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、特定の濃度のチオ尿素の存在下で混合するものであるため、白金族元素が吸着した水溶性高分子の劣化を抑制しながら、白金族元素の回収を行うことができるものであり、これにより、高い回収率での白金族元素の回収を実現しつつ、白金族元素を回収した後の水溶性高分子については、高い吸着率を維持した状態にて回収することができ、そのため、白金族元素を吸着させる用途に好適に再利用することができるものである。加えて、本発明の回収方法においては、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際に、白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％として混合を行うため、これにより、白金族元素を脱離させた後の水溶性高分子を高い回収率で回収することができるものであり、このような観点からも、白金族元素を吸着させる用途に好適に再利用することができるものである。 In particular, in the recovery method of the present invention, the above-mentioned aqueous solution of hydrochloric acid having a predetermined concentration is prepared in advance, and the aqueous solution of hydrochloric acid prepared in advance and the water-soluble polymer adsorbed by the platinum group element are provided at a specific concentration. Since it is mixed in the presence of thiourea, it is possible to recover the platinum group element while suppressing the deterioration of the water-soluble polymer adsorbed by the platinum group element, thereby achieving a high recovery rate. The water-soluble polymer after the recovery of the platinum group element can be recovered while maintaining a high adsorption rate while realizing the recovery of the platinum group element in the above. Therefore, the platinum group element is adsorbed. It can be reused suitable for the intended use. In addition, in the recovery method of the present invention, when the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, the water-soluble polymer adsorbed by the platinum group element is used. Since the mixing is carried out with the content ratio set to 16 to 72% by weight, the water-soluble polymer after desorption of the platinum group element can be recovered with a high recovery rate from this viewpoint. Also, it can be suitably reused for the purpose of adsorbing platinum group elements.

以下、本発明を、さらに詳細な実施例に基づき説明するが、本発明は、これら実施例に限定されない。なお、以下において、「部」は、特に断りのない限り重量基準である。 Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, "part" is based on weight unless otherwise specified.

＜製造例１＞
（水素化アクリロニトリル−ブタジエン共重合体の製造）
反応器に、オレイン酸カリウム２部、イオン交換水１８０部、アクリロニトリル３７部、およびｔ−ドデシルメルカプタン０．５部を、この順に仕込んだ。次いで、反応器内部を窒素で置換した後、ブタジエン６３部を添加し、反応器を１０℃に冷却して、クメンハイドロパーオキサイド０．０１部、および硫酸第一鉄０．０１部を添加した。次いで、反応器を１０℃に保ったまま内容物を１６時間攪拌した。その後、反応器内へ１０重量％のハイドロキノン水溶液を添加して重合反応を停止させた後、重合反応液から未反応の単量体を除去することで、アクリロニトリル−ブタジエン共重合体のラテックスを得た。重合転化率は９０％であった。<Manufacturing example 1>
(Production of hydrogenated acrylonitrile-butadiene copolymer)
The reactor was charged with 2 parts of potassium oleate, 180 parts of ion-exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecyl mercaptan in this order. Then, after replacing the inside of the reactor with nitrogen, 63 parts of butadiene was added, the reactor was cooled to 10 ° C., and 0.01 part of cumene hydroperoxide and 0.01 part of ferrous sulfate were added. .. The contents were then stirred for 16 hours while keeping the reactor at 10 ° C. Then, a 10 wt% hydroquinone aqueous solution was added into the reactor to stop the polymerization reaction, and then the unreacted monomer was removed from the polymerization reaction solution to obtain a latex of an acrylonitrile-butadiene copolymer. It was. The polymerization conversion rate was 90%.

次いで、上記とは別の反応器に、塩化カルシウム（凝固剤）３部を溶解した凝固水３００部を入れ、これを５０℃で攪拌しながら、上記にて得られたラテックスを凝固水中へ滴下した。そして、ここへ水酸化カリウム水溶液を加えてｐＨを１１．５に保ちながら重合体クラムを析出させた後、凝固水から重合体クラムを分取して水洗後、５０℃で減圧乾燥した。次いで、得られた重合体クラムをアセトンに溶解することで、重合体含量が１５重量％のアセトン溶液を調製した。 Next, 300 parts of coagulated water in which 3 parts of calcium chloride (coagulant) was dissolved was placed in a reactor different from the above, and the latex obtained above was dropped into the coagulated water while stirring this at 50 ° C. did. Then, an aqueous potassium hydroxide solution was added to precipitate the polymer crumbs while maintaining the pH at 11.5, the polymer crumbs were separated from the coagulated water, washed with water, and dried under reduced pressure at 50 ° C. Then, the obtained polymer crumb was dissolved in acetone to prepare an acetone solution having a polymer content of 15% by weight.

そして、得られたアクリロニトリル−ブタジエン共重合体のアセトン溶液にシリカ担持型パラジウム（Ｐｄ）触媒（Ｐｄ量は「Ｐｄ金属／アクリロニトリル−ブタジエン共重合体」の比で１０００重量ｐｐｍ）を加えて、これを攪拌機付オートクレーブに投入し、窒素ガスを１０分間流すことで溶存酸素を除去した。次いで、系内を２回水素ガスで置換後、５ＭＰａの水素を加圧し、内容物を５０℃に加温して６時間攪拌することで、水素化反応を行った。 Then, a silica-supported palladium (Pd) catalyst (the amount of Pd is 1000 ppm by weight in the ratio of "Pd metal / acrylonitrile-butadiene copolymer") is added to the acetone solution of the obtained acrylonitrile-butadiene copolymer. Was put into an autoclave equipped with a stirrer, and dissolved oxygen was removed by flowing nitrogen gas for 10 minutes. Next, the inside of the system was replaced with hydrogen gas twice, hydrogen of 5 MPa was pressurized, the contents were heated to 50 ° C., and the mixture was stirred for 6 hours to carry out a hydrogenation reaction.

水素化反応終了後、反応系を室温に冷却し、系内の水素を窒素で置換した。そして、水素化反応により得られた水素化アクリロニトリル−ブタジエン共重合体の溶液について、濾過を行うことで、シリカ担持型パラジウム触媒を回収し、ろ過後の水素化アクリロニトリル−ブタジエン共重合体の溶液を得た。 After completion of the hydrogenation reaction, the reaction system was cooled to room temperature, and hydrogen in the system was replaced with nitrogen. Then, the solution of the hydrogenated acrylonitrile-butadiene copolymer obtained by the hydrogenation reaction is filtered to recover the silica-supported palladium catalyst, and the filtered solution of the hydrogenated acrylonitrile-butadiene copolymer is obtained. Obtained.

上記にて得られた、ろ過後の水素化アクリロニトリル−ブタジエン共重合体の溶液のうち一部を採取し、これを１０倍量の水中に投入して、共重合体を析出させ、得られた共重合体を真空乾燥機で２４時間乾燥することで、固形状の水素化アクリロニトリル−ブタジエン共重合体を得た。得られた固形状の水素化アクリロニトリル−ブタジエン共重合体について、原子吸光測定により、共重合体中のパラジウム量を測定したところ、パラジウム量は１５１重量ｐｐｍであった。また、ＪＩＳ Ｋ６２３５に準じてヨウ素価を測定したところ、ヨウ素価は、７．６であった。 A part of the filtered solution of the hydrided acrylonitrile-butadiene copolymer obtained above was collected and put into 10 times the amount of water to precipitate the copolymer, which was obtained. The copolymer was dried in a vacuum dryer for 24 hours to obtain a solid hydride acrylonitrile-butadiene copolymer. When the amount of palladium in the obtained solid hydrogenated acrylonitrile-butadiene copolymer was measured by atomic absorption spectroscopy, the amount of palladium was 151 wt ppm. Moreover, when the iodine value was measured according to JIS K6235, the iodine value was 7.6.

＜製造例２＞
（水溶性高分子の製造）
反応器に、Ｎ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）１０部、イオン交換水３７部を仕込み、次いで、反応器内部を窒素で置換した後、反応器を７５℃に加温して、ペルオキソ二硫酸アンモニウム０．３５部を添加した。次いで、反応器を７５℃に保ったまま内容物を１時間攪拌した。得られた高分子水溶液をアセトン中へ滴下し、重合体を析出させた後、アセトン中から重合体を分取してアセトン洗浄を行った後、５０℃で減圧乾燥することにより固体状の水溶性高分子（ポリ（Ｎ，Ｎ−ジメチルアミノエチルメタクリレート））を得た。得られた水溶性高分子について、ＧＰＣ測定により、ポリスチレン換算の重量平均分子量（Ｍｗ）を測定したところ、重量平均分子量（Ｍｗ）は６５０，０００であった。そして、得られた水溶性高分子１部をイオン交換水１０部に溶かして水溶性高分子の水溶液（水溶性高分子の濃度：９．１重量％）を得た。<Manufacturing example 2>
(Manufacturing of water-soluble polymer)
The reactor was charged with 10 parts of N, N-dimethylaminoethyl methacrylate (DMAEMA) and 37 parts of ion-exchanged water, and then the inside of the reactor was replaced with nitrogen, and then the reactor was heated to 75 ° C. to peroxo. 0.35 part of ammonium disulfate was added. The contents were then stirred for 1 hour while keeping the reactor at 75 ° C. The obtained aqueous polymer solution is dropped into acetone to precipitate a polymer, the polymer is separated from the acetone, washed with acetone, and dried under reduced pressure at 50 ° C. to form a solid water-soluble substance. A sex polymer (poly (N, N-dimethylaminoethyl methacrylate)) was obtained. When the polystyrene-equivalent weight average molecular weight (Mw) of the obtained water-soluble polymer was measured by GPC measurement, the weight average molecular weight (Mw) was 650,000. Then, 1 part of the obtained water-soluble polymer was dissolved in 10 parts of ion-exchanged water to obtain an aqueous solution of the water-soluble polymer (concentration of the water-soluble polymer: 9.1% by weight).

＜参考例１＞
（水溶性高分子を用いた、水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離）
製造例１で得られた、ろ過後の水素化アクリロニトリル−ブタジエン共重合体の溶液を一部採取し、これをバイアルに移し、水素化アクリロニトリル−ブタジエン共重合体の濃度が８重量％となるように、アセトンを添加して濃度調整を行った後、水素化アクリロニトリル−ブタジエン共重合体１００部に対して、製造例２で得られた水溶性高分子の水溶液２５部を添加した。次いで、振とう器（商品名「ＲＥＣＩＰＲＯ ＳＨＡＫＥＲ ＳＲ−１」、タイテック社製）を使用して、２５℃、１００ｒｐｍの条件にて、２４時間攪拌を行った。そして、２４時間の撹拌により、水溶性高分子は固体となって沈降した。次いで、ろ過を行うことにより、パラジウムを吸着させた水溶性高分子を得た。そして、得られた固形状の水溶性高分子について、原子吸光測定により、水溶性高分子中のパラジウム量を測定したところ、パラジウム量は５４３重量ｐｐｍであった。<Reference example 1>
(Separation of palladium from a solution of hydrogenated acrylonitrile-butadiene copolymer using a water-soluble polymer)
A part of the filtered solution of the hydride acrylonitrile-butadiene copolymer obtained in Production Example 1 was collected and transferred to a vial so that the concentration of the hydride acrylonitrile-butadiene copolymer was 8% by weight. After adjusting the concentration by adding acetone, 25 parts of the aqueous solution of the water-soluble polymer obtained in Production Example 2 was added to 100 parts of the hydride acrylonitrile-butadiene copolymer. Then, using a shaker (trade name "RECIPRO SHAKER SR-1", manufactured by TIETECH Co., Ltd.), stirring was performed at 25 ° C. and 100 rpm for 24 hours. Then, by stirring for 24 hours, the water-soluble polymer became a solid and settled. Then, filtration was performed to obtain a water-soluble polymer on which palladium was adsorbed. Then, when the amount of palladium in the water-soluble polymer was measured by atomic absorption spectroscopy with respect to the obtained solid water-soluble polymer, the amount of palladium was 543 parts by weight ppm.

＜実施例１＞
（パラジウムを吸着させた水溶性高分子からのパラジウムの回収）
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度１６．６重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液を得た。得られたチオ尿素含有塩酸水溶液１００部に、参考例１において得られた、パラジウムを吸着させた固体状の水溶性高分子１００部投入し、次いで、振とう器（商品名「ＲＥＣＩＰＲＯ ＳＨＡＫＥＲ ＳＲ−１」、タイテック社製）を使用して、２５℃、１２０ｒｐｍの条件にて４時間撹拌を行った。その後、攪拌後の混合液を、等量以上のアセトンに投入し、振とう器（商品名「ＲＥＣＩＰＲＯ ＳＨＡＫＥＲ ＳＲ−１」、タイテック社製）を使用して撹拌し、ろ過をすることで、水溶性高分子の沈殿物を得た。得られた固形状の水溶性高分子について、原子吸光測定により、水溶性高分子中のパラジウム量を測定したところ、パラジウム量は１６．４重量ｐｐｍまで減少していた。また、ろ過により、回収された水溶性高分子の沈殿物の量は、９９．２部であり、水溶性高分子の回収率（水溶性高分子の回収率（重量％）＝（回収された水溶性高分子の沈殿物の量÷チオ尿素含有塩酸水溶液中に投入した水溶性高分子の量）×１００）は９９．２重量％であった。<Example 1>
(Recovery of palladium from a water-soluble polymer on which palladium is adsorbed)
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 16.6% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 6.9% by weight was obtained. To 100 parts of the obtained aqueous hydrochloric acid solution containing thiourea, 100 parts of the solid water-soluble polymer obtained in Reference Example 1 on which palladium was adsorbed was added, and then a shaker (trade name "RECIPRO SHAKER SR-") was added. 1 ”, manufactured by Tietech Co., Ltd.) was used to stir for 4 hours under the conditions of 25 ° C. and 120 rpm. After that, the mixed solution after stirring is put into an equal amount or more of acetone, stirred using a shaker (trade name "RECIPRO SHAKER SR-1", manufactured by TIETECH Co., Ltd.), and filtered to make it water-soluble. A precipitate of sex polymer was obtained. When the amount of palladium in the water-soluble polymer was measured by atomic absorption spectrometry on the obtained solid water-soluble polymer, the amount of palladium was reduced to 16.4 ppm by weight. The amount of the water-soluble polymer precipitate recovered by filtration was 99.2 parts, and the recovery rate of the water-soluble polymer (recovery rate of the water-soluble polymer (% by weight) = (recovered). The amount of the water-soluble polymer precipitate ÷ the amount of the water-soluble polymer charged into the thiourea-containing aqueous hydrochloric acid solution) × 100) was 99.2% by weight.

（水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離）
そして、回収された水溶性高分子の沈殿物１部を、再度、イオン交換水１０部に溶かして水溶性高分子の水溶液（水溶性高分子の濃度：９．１重量％）とし、上述した参考例１と同様にして、水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離操作を行った。その結果、得られた固形状の水溶性高分子について、原子吸光測定により、水溶性高分子中のパラジウム量を測定したところ、パラジウム量は５２８．１重量ｐｐｍであり、上記にて回収操作を経た、水溶性高分子によれば、水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離操作に、好適に再利用できるものであった。(Separation of palladium from solution of hydrogenated acrylonitrile-butadiene copolymer)
Then, 1 part of the recovered water-soluble polymer precipitate was dissolved again in 10 parts of ion-exchanged water to prepare an aqueous solution of the water-soluble polymer (concentration of the water-soluble polymer: 9.1% by weight), which was described above. In the same manner as in Reference Example 1, the operation of separating palladium from the solution of the hydride acrylonitrile-butadiene copolymer was carried out. As a result, when the amount of palladium in the water-soluble polymer was measured by atomic absorption spectroscopy with respect to the obtained solid water-soluble polymer, the amount of palladium was 528.1 wt ppm, and the recovery operation was performed as described above. According to the water-soluble polymer, it can be suitably reused for the operation of separating palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer.

そして、上記した「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を、同様にして、繰り返し２回行った（合計で３回）。１回目、２回目、３回目における、各結果を表１に示す。なお、表１中、「水溶性高分子の回収率」は、その値が高いほど、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」を行った後における、水溶性高分子の回収量が多くなるため好ましい。実施例１においては、「水溶性高分子の回収率」は、１回目：９９．２重量％、２回目：９９．５重量％、３回目：９９．１重量％と、いずれも高い水準であった。また、「水溶性高分子中のパラジウム残留量」は、その値が低いほど、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」を行った際における、回収効率が高いと判断できるため、好ましい。実施例１においては、「水溶性高分子中のパラジウム残留量」は、１回目：１６．４重量ｐｐｍ、２回目：１７．３重量ｐｐｍ、３回目：１６．９重量ｐｐｍと、いずれも低く抑えられたものであった。さらに、表１中、「再利用後の水溶性高分子中におけるパラジウム吸着量」は、その値が高いほど、水溶性高分子を、「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」操作に再利用した際における、吸着効率が高いと判断できるため、好ましい。実施例１においては、「再利用後の水溶性高分子中におけるパラジウム吸着量」は、１回目：５２８．１重量ｐｐｍ、２回目：５２５．３重量ｐｐｍ、３回目：５２６．４重量ｐｐｍと、いずれも高く、吸着効率に優れたものであった。 Then, the above-mentioned operations of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" are repeated twice in the same manner. I went (3 times in total). Table 1 shows the results of the first, second, and third times. In Table 1, the higher the value of "recovery rate of water-soluble polymer", the higher the value of the water-soluble polymer after "recovery of palladium from the water-soluble polymer adsorbed with palladium". This is preferable because the amount of recovery is large. In Example 1, the "recovery rate of the water-soluble polymer" was as high as 99.2% by weight for the first time, 99.5% by weight for the second time, and 99.1% by weight for the third time. there were. Further, as for the "residual amount of palladium in the water-soluble polymer", it can be judged that the lower the value, the higher the recovery efficiency when "recovering palladium from the water-soluble polymer adsorbed with palladium". Therefore, it is preferable. In Example 1, the "residual amount of palladium in the water-soluble polymer" was low, 1st time: 16.4% by weight ppm, 2nd time: 17.3% by weight ppm, and 3rd time: 16.9% by weight ppm. It was suppressed. Further, in Table 1, the higher the value of "amount of palladium adsorbed in the recycled water-soluble polymer", the more the water-soluble polymer is "palladium from the solution of hydrogenated acrylonitrile-butadiene copolymer". It is preferable because it can be judged that the adsorption efficiency is high when it is reused for the "separation" operation. In Example 1, the "amount of palladium adsorbed in the water-soluble polymer after reuse" was as follows: 1st time: 528.1% by weight ppm, 2nd time: 525.3% by weight ppm, 3rd time: 526.4% by weight ppm. All of them were high and had excellent adsorption efficiency.

＜実施例２＞
塩酸濃度１６．６重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部に対する、パラジウムを吸着させた固体状の水溶性高分子の投入量を５０部に変更したこと、および、振とう器を使用した攪拌時間を２時間に変更したこと以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 2>
The amount of the solid water-soluble polymer adsorbed with palladium was changed to 50 parts with respect to 100 parts of the thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.6% by weight and a thiourea concentration of 6.9% by weight. In the same manner as in Example 1, "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "hydrochloric acid acrylonitrile-butadiene", except that the stirring time using the shaker was changed to 2 hours. Each operation of "separation of palladium from the copolymer solution" was repeated 3 times in total. Table 1 shows the results of the first, second, and third times.

＜実施例３＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、およびチオ尿素（和光純薬社製、試薬特級）を、イオン交換水にて希釈し、塩酸濃度３０．９重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度３０．９重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 3>
A commercially available aqueous hydrochloric acid solution having a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) and thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) were diluted with ion-exchanged water to have a hydrochloric acid concentration of 30.9% by weight. , A thiourea-containing hydrochloric acid aqueous solution having a thiourea concentration of 6.9% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 30.9% by weight and a thiourea concentration of 6.9% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜実施例４＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度０．４重量％、チオ尿素濃度７．４重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度０．４重量％、チオ尿素濃度７．４重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 4>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration is 0.4% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 7.4% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 0.4% by weight and a thiourea concentration of 7.4% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜実施例５＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度１５．４重量％、チオ尿素濃度３２．０重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度１５．４重量％、チオ尿素濃度３２．０重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 5>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 15.4% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 32.0% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 15.4% by weight and a thiourea concentration of 32.0% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜実施例６＞
塩酸濃度１６．６重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部に対する、パラジウムを吸着させた固体状の水溶性高分子の投入量を２５部に変更した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 6>
Except for changing the input amount of the solid water-soluble polymer adsorbed palladium to 25 parts with respect to 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.6% by weight and a thiourea concentration of 6.9% by weight. In the same manner as in Example 1, each operation of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydride acrylonitrile-butadiene copolymer" is repeated three times in total. went. Table 1 shows the results of the first, second, and third times.

＜実施例７＞
塩酸濃度１６．６重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部に対する、パラジウムを吸着させた固体状の水溶性高分子の投入量を１８５部に変更した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Example 7>
Except for changing the input amount of the solid water-soluble polymer adsorbed palladium to 185 parts with respect to 100 parts of the thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.6% by weight and a thiourea concentration of 6.9% by weight. In the same manner as in Example 1, each operation of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydride acrylonitrile-butadiene copolymer" is repeated three times in total. went. Table 1 shows the results of the first, second, and third times.

＜比較例１＞
参考例１において得られた、パラジウムを吸着させた水溶性高分子１００部をイオン交換水７７．６５部に溶解し、水溶性高分子の水溶液を得た。得られた水溶性高分子の水溶液１７７．６５部に、濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）１８．９部、およびチオ尿素（和光純薬社製、試薬特級）３．４５部を添加した以外は、実施例１と同様にして、振とう器による混合等の操作を行うことで、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」を行った。そして、実施例１と同様に、このような「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative example 1>
100 parts of the water-soluble polymer adsorbed with palladium obtained in Reference Example 1 was dissolved in 77.65 parts of ion-exchanged water to obtain an aqueous solution of the water-soluble polymer. In addition to 177.65 parts of the obtained aqueous solution of the water-soluble polymer, 18.9 parts of a commercially available hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) having a concentration of 12 mol / L, and thiourea (manufactured by Wako Pure Chemical Industries, Ltd., reagent). "Recovery of palladium from the water-soluble polymer adsorbed with palladium" by performing operations such as mixing with a shaker in the same manner as in Example 1 except that 3.45 parts of (special grade) was added. went. Then, as in Example 1, each of the operations of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer". Was repeated 3 times in total. Table 1 shows the results of the first, second, and third times.

＜比較例２＞
振とう器を使用した攪拌時間を１時間に変更したこと以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative example 2>
"Recovery of palladium from a water-soluble polymer adsorbed with palladium" and "Hydrogenated acrylonitrile-butadiene" in the same manner as in Example 1 except that the stirring time using a shaker was changed to 1 hour. Each operation of "separation of palladium from the solution of the polymer" was repeated 3 times in total. Table 1 shows the results of the first, second, and third times.

＜比較例３＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度３２．３重量％、チオ尿素濃度６．４重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度３２．３重量％、チオ尿素濃度６．４重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からのパラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からのパラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative example 3>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 32.3% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 6.4% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 32.3% by weight and a thiourea concentration of 6.4% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜比較例４＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度３３．６重量％、チオ尿素濃度６．４重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度３３．６重量％、チオ尿素濃度６．４重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative example 4>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 33.6% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 6.4% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 33.6% by weight and a thiourea concentration of 6.4% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜比較例５＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度０．２重量％、チオ尿素濃度７．４重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度０．２重量％、チオ尿素濃度７．４重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative example 5>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration is 0.2% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 7.4% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 0.2% by weight and a thiourea concentration of 7.4% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜比較例６＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度１６．９重量％、チオ尿素濃度０．７重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度１６．９重量％、チオ尿素濃度０．７重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative Example 6>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 16.9% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 0.7% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.9% by weight and a thiourea concentration of 0.7% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜比較例７＞
濃度１２ｍｏｌ／Ｌの市販の塩酸水溶液（和光純薬社製、試薬特級）、チオ尿素（和光純薬社製、試薬特級）、およびイオン交換水を用いて、塩酸濃度１６．９重量％、チオ尿素濃度０．４重量％のチオ尿素含有塩酸水溶液を得た。そして、上記にて調製した塩酸濃度１６．９重量％、チオ尿素濃度０．４重量％のチオ尿素含有塩酸水溶液１００部を使用した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative Example 7>
Using a commercially available aqueous hydrochloric acid solution with a concentration of 12 mol / L (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), thiourea (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), and ion-exchanged water, the hydrochloric acid concentration was 16.9% by weight, thio. A thiourea-containing hydrochloric acid aqueous solution having a urea concentration of 0.4% by weight was obtained. Then, "palladium is adsorbed" in the same manner as in Example 1 except that 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.9% by weight and a thiourea concentration of 0.4% by weight prepared above was used. Each operation of "recovery of palladium from the water-soluble polymer" and "separation of palladium from the solution of the hydrogenated acrylonitrile-butadiene copolymer" was repeated three times in total. Table 1 shows the results of the first, second, and third times.

＜比較例８＞
塩酸濃度１６．９重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部に対する、パラジウムを吸着させた固体状の水溶性高分子の投入量を１７部に変更した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative Example 8>
Except for changing the input amount of the solid water-soluble polymer adsorbed palladium to 17 parts with respect to 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.9% by weight and a thiourea concentration of 6.9% by weight. In the same manner as in Example 1, each operation of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydrochloric acid hydride-butadiene copolymer" is performed for a total of 3 operations. Repeated times. Table 1 shows the results of the first, second, and third times.

＜比較例９＞
塩酸濃度１６．９重量％、チオ尿素濃度６．９重量％のチオ尿素含有塩酸水溶液１００部に対する、パラジウムを吸着させた固体状の水溶性高分子の投入量を３００部に変更した以外は、実施例１と同様にして、「パラジウムを吸着させた水溶性高分子からの、パラジウムの回収」および「水素化アクリロニトリル−ブタジエン共重合体の溶液からの、パラジウムの分離」の各操作を合計３回繰り返し行った。１回目、２回目、３回目における、各結果を表１に示す。<Comparative Example 9>
Except for changing the input amount of the solid water-soluble polymer adsorbed palladium to 300 parts with respect to 100 parts of a thiourea-containing hydrochloric acid aqueous solution having a hydrochloric acid concentration of 16.9% by weight and a thiourea concentration of 6.9% by weight. In the same manner as in Example 1, each operation of "recovery of palladium from the water-soluble polymer adsorbed with palladium" and "separation of palladium from the solution of the hydrochloric acid hydride-butadiene copolymer" is performed for a total of 3 operations. Repeated times. Table 1 shows the results of the first, second, and third times.

Figure 2019188708
Figure 2019188708

表１に示すように、０．２５〜３１．５０重量％の塩酸を含有する塩酸水溶液を予め準備し、予め準備した塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、混合液中における、白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％、チオ尿素の含有割合を０．５〜２０．０重量％となるように、１．５時間以上混合することにより、水溶性高分子の回収率が高くなり、水溶性高分子中のパラジウム残留量が低く抑えられており、さらには、再利用後の水溶性高分子中におけるパラジウム吸着量を高くすることができ、良好な結果であった（実施例１〜７）。 As shown in Table 1, a hydrochloric acid aqueous solution containing 0.25 to 31.50% by weight of hydrochloric acid is prepared in advance, and the prepared hydrochloric acid aqueous solution and a water-soluble polymer adsorbed with a platinum group element are mixed. Mix for 1.5 hours or more so that the content ratio of the water-soluble polymer adsorbed by the platinum group element is 16 to 72% by weight and the content ratio of thiourea is 0.5 to 20.0% by weight. As a result, the recovery rate of the water-soluble polymer is high, the residual amount of palladium in the water-soluble polymer is suppressed to a low level, and the amount of palladium adsorbed in the water-soluble polymer after reuse is increased. The results were good (Examples 1 to 7).

一方、白金族元素が吸着した水溶性高分子を水溶液の状態とし、ここに、濃度１２ｍｏｌ／Ｌ（濃度３７重量％）の塩酸使用液を添加した場合や、予め調製する塩酸水溶液中における塩酸濃度が高すぎる場合には、水溶性高分子の劣化が起こり、再利用後の水溶性高分子中におけるパラジウム吸着量が低くなる結果となった（比較例１，３，４）。
また、塩酸水溶液と、白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で混合する際における、混合時間が短すぎる場合や、予め調製する塩酸水溶液中における塩酸濃度が低すぎる場合、さらには、チオ尿素の濃度が低すぎる場合には、水溶性高分子中のパラジウム残留量が高くなり、水溶性高分子からのパラジウムの回収効率に劣る結果となった（比較例２，５，６，７）。
さらに、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、白金族元素が吸着した水溶性高分子の含有割合が低すぎる場合には、水溶性高分子の回収率が低くなる結果となった（比較例８）。
また、塩酸水溶液と、白金族元素が吸着した水溶性高分子とを、チオ尿素の存在下で混合する際における、白金族元素が吸着した水溶性高分子の含有割合が高すぎる場合には、水溶性高分子中のパラジウム残留量が高くなり、水溶性高分子からのパラジウムの回収効率に劣る結果となった（比較例９）。On the other hand, when a water-soluble polymer adsorbed with a platinum group element is made into an aqueous solution and a hydrochloric acid-using solution having a concentration of 12 mol / L (concentration 37% by weight) is added thereto, or the hydrochloric acid concentration in a hydrochloric acid aqueous solution prepared in advance If it is too high, the water-soluble polymer deteriorates, resulting in a low adsorption amount of palladium in the reused water-soluble polymer (Comparative Examples 1, 3 and 4).
Further, when the hydrochloric acid aqueous solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, the mixing time is too short, or the hydrochloric acid concentration in the hydrochloric acid aqueous solution prepared in advance is too low. Furthermore, when the concentration of thiourea is too low, the residual amount of palladium in the water-soluble polymer becomes high, resulting in inferior efficiency in recovering palladium from the water-soluble polymer (Comparative Examples 2 and 5). , 6, 7).
Further, when the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, when the content ratio of the water-soluble polymer adsorbed by the platinum group element is too low, The result was that the recovery rate of the water-soluble polymer was low (Comparative Example 8).
Further, when the aqueous hydrochloric acid solution and the water-soluble polymer adsorbed by the platinum group element are mixed in the presence of thiourea, when the content ratio of the water-soluble polymer adsorbed by the platinum group element is too high, The residual amount of palladium in the water-soluble polymer became high, resulting in inferior efficiency in recovering palladium from the water-soluble polymer (Comparative Example 9).

Claims (9)

白金族元素が吸着した水溶性高分子から白金族元素を回収する方法であって、
０．２５〜３１．５０重量％の塩酸を含有する塩酸水溶液を準備する準備工程と、
前記準備工程において準備した前記塩酸水溶液と、前記白金族元素が吸着した水溶性高分子とをチオ尿素の存在下で、１．５時間以上混合する混合工程とを備え、
前記混合工程における混合液中の、前記チオ尿素の含有割合を０．５〜２０．０重量％、前記白金族元素が吸着した水溶性高分子の含有割合を１６〜７２重量％として混合を行う白金族元素の回収方法。A method of recovering a platinum group element from a water-soluble polymer adsorbed by the platinum group element.
A preparatory step for preparing an aqueous hydrochloric acid solution containing 0.25 to 31.50% by weight of hydrochloric acid, and
A mixing step of mixing the hydrochloric acid aqueous solution prepared in the preparation step with the water-soluble polymer adsorbed by the platinum group element in the presence of thiourea for 1.5 hours or more is provided.
Mixing is carried out with the content of the thiourea in the mixed solution in the mixing step being 0.5 to 20.0% by weight and the content of the water-soluble polymer adsorbed by the platinum group element being 16 to 72% by weight. Method for recovering platinum group elements. 前記混合工程における混合液中の、前記塩酸の含有割合を１．０〜１６．０重量％とする請求項１に記載の白金族元素の回収方法。 The method for recovering a platinum group element according to claim 1, wherein the content ratio of the hydrochloric acid in the mixed solution in the mixing step is 1.0 to 16.0% by weight. 前記水溶性高分子が、アミノ基含有（メタ）アクリレート系重合体である請求項１または２に記載の白金族元素の回収方法。 The method for recovering a platinum group element according to claim 1 or 2, wherein the water-soluble polymer is an amino group-containing (meth) acrylate-based polymer. 前記アミノ基含有（メタ）アクリレート系重合体が、Ｎ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）の単独重合体、またはＮ，Ｎ−ジメチルアミノエチルメタクリレート（ＤＭＡＥＭＡ）を含む２種以上の単量体の共重合体である請求項３に記載の白金族元素の回収方法。 The amino group-containing (meth) acrylate-based polymer is a homopolymer of N, N-dimethylaminoethyl methacrylate (DMAEMA) or two or more kinds of monomers containing N, N-dimethylaminoethyl methacrylate (DMAEMA). The method for recovering a platinum group element according to claim 3, which is a copolymer of. 前記白金族元素が、パラジウムである請求項１〜４のいずれかに記載の白金族元素の回収方法。 The method for recovering a platinum group element according to any one of claims 1 to 4, wherein the platinum group element is palladium. 前記白金族元素が、ニトリルゴムの水素化反応に用いた白金族元素含有触媒に由来の白金族元素である、請求項１〜５のいずれかに記載の白金族元素の回収方法。 The method for recovering a platinum group element according to any one of claims 1 to 5, wherein the platinum group element is a platinum group element derived from a platinum group element-containing catalyst used in the hydrogenation reaction of nitrile rubber. 前記混合工程が、前記準備工程において準備した前記塩酸水溶液と、前記チオ尿素とを予め混合することで、チオ尿素を含有する塩酸水溶液を得た後に、該チオ尿素を含有する塩酸水溶液に、前記白金族元素が吸着した水溶性高分子を添加して混合する工程である請求項１〜６のいずれかに記載の白金族元素の回収方法。 In the mixing step, the hydrochloric acid aqueous solution prepared in the preparation step and the thiourea are mixed in advance to obtain a hydrochloric acid aqueous solution containing thiourea, and then the hydrochloric acid aqueous solution containing the thiourea is added. The method for recovering a platinum group element according to any one of claims 1 to 6, which is a step of adding and mixing a water-soluble polymer in which a platinum group element is adsorbed. 前記チオ尿素を含有する塩酸水溶液中における、前記チオ尿素の含有割合が、１．０〜３５．０重量％である請求項７に記載の白金族元素の回収方法。 The method for recovering a platinum group element according to claim 7, wherein the content ratio of the thiourea in the aqueous hydrochloric acid solution containing the thiourea is 1.0 to 35.0% by weight. 前記混合工程において、前記準備工程において準備した前記塩酸水溶液に、前記白金族元素が吸着した水溶性高分子を添加する際に、前記白金族元素が吸着した水溶性高分子を固体の状態で添加する請求項１〜８のいずれかに記載の白金族元素の回収方法。 In the mixing step, when the water-soluble polymer adsorbed by the platinum group element is added to the hydrochloric acid aqueous solution prepared in the preparation step, the water-soluble polymer adsorbed by the platinum group element is added in a solid state. The method for recovering a platinum group element according to any one of claims 1 to 8.
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