JP3887487B2 - Filter and liquid cleaning method using the filter - Google Patents

Description

【００１３】
（式中、Ｒ¹ ，Ｒ² ，Ｒ³ は低級アルキレン基、ｎは１〜４の整数を表わす）
【００１４】
該フィルターの主たる構成要素となるキレート形成性繊維は、ベース繊維を構成する分子の反応性官能基に直接、もしくは繊維を構成する分子に他の反応性官能基を導入した後、該官能基に下記一般式［２］で示されるポリカルボン酸の酸無水物を反応させることによって得たものが好ましく使用され、
【００１５】
【化４】

【００１６】
（式中、Ｒ¹ ，Ｒ² ，Ｒ³ は低級アルキレン基、ｎは１〜４の整数を表わす）
【００１７】
金属イオン捕捉能を高める上では、前記アシル基の下記式によって計算される置換率が１０重量％以上であるキレート形成性繊維を使用することが望ましい。
置換率（重量％）＝［（反応後の繊維重量−反応前の繊維重量）／反応前の繊維重量］×１００
【００１８】
また、該キレート生成性繊維を製造する際に使用される前記一般式［２］で示されるポリカルボン酸の酸無水物としては、ニトリロ三酢酸無水物、エチレンジアミン四酢酸２無水物、ジエチレントリアミン五酢酸２無水物よりなる群から選択される少なくとも１種が好ましく、又これらキレート形成性官能基が導入されるベース繊維としては、天然繊維、再生繊維、合成繊維を単独で、あるいは必要により２種以上を組合せて使用できる。
【００１９】
また本発明に係る清浄化法は、前述したフィルターに水性液や油性液などの液体を通し、該液体中の金属イオンと不溶性夾雑物を除去して清浄化するところに特徴を有している。
【００２０】
【発明の実施の形態】
本発明に係るフィルターの構成素材となる金属キレート形成性繊維は、上記の様に、繊維分子中に前記一般式［１］で示されるアシル基を置換基として有し、このアシル基は、その中に存在する窒素やカルボン酸が銅、亜鉛、ニッケル、コバルト等の重金属イオンに対して優れた選択吸着性を有しており、且つ該選択吸着活性基が繊維表面に露出しているので、この繊維は、該アシル基の存在によって優れた金属イオン選択吸着活性を発揮する。
【００２１】
尚、前記一般式［１］のＲ¹ 〜Ｒ³ で示される低級アルキレン基としては、Ｃ₁ 〜Ｃ₆ のアルキレン基が挙げられるが、中でも特に好ましいのはメチレン、エチレン、プロピレンである。また繰り返し数ｎとして特に好ましいのは１または２である。
【００２２】
金属キレート形成能が付与されるベース繊維の種類は特に制限されず、例えば綿、麻などを始めとする種々の植物繊維；絹、羊毛などを始めとする種々の動物性繊維；ビスコースレーヨン、アセテートなどを始めとする種々の再生繊維；ポリアミド、アクリル、ポリエステルなどを始めとする様々の合成繊維を使用することができ、これらの繊維は必要に応じて各種の変性を加えたものであっても構わない。
【００２３】
これらベース繊維の中でも特に好ましいのは、繊維分子中にヒドロキシル基やアミノ基等の反応性官能基を有する植物性繊維や動物性繊維、再生繊維であり、これらの繊維であれば、該繊維分子中の反応性官能基を利用して前述の様な金属キレート形成能を持った基を容易に導入することができるので好ましい。もっとも、原料繊維自体が反応性官能基を有していない場合であっても、これを酸化など任意の手段で変性して反応性官能基を導入し、この官能基を利用して前述の様な基を導入することも可能である。
【００２４】
ここで用いられる繊維の性状にも特に制限がなく、長繊維のマルチフィラメント、短繊維の紡績糸、あるいはこれらを織物状や編物状に製織若しくは製編した布帛、更には不織布であってもよく、２種以上の繊維を複合もしくは混紡した繊維や織・編物を使用することも勿論有効である。また木材パルプや紙、更には木材片や木材チップ、薄板などを使用することも可能である。
【００２５】
そして分子中に上記反応性官能基を有する上記繊維に、前記一般式［２］で示されるポリカルボン酸の酸無水物を反応させると、該繊維分子中に前記一般式［１］で示されるアシル基がペンダント状に導入されるが、該アシル基中のカルボン酸は金属イオンとのキレート反応性が非常に高く、従って該アシル基の導入された繊維を用いて金属イオンを含む被処理液を処理すると、その中に含まれる金属イオンは金属キレートを形成して効率よく捕捉される。
【００２６】
上記一般式［１］で示されるアシル基の導入に用いられる、前記一般式［２］で示されるポリカルボン酸の酸無水物の好ましい具体例としては、ニトリロ三酢酸・無水物（ＮＴＡ無水物）、エチレンジアミン四酢酸・二無水物（ＥＤＴＡ・二無水物）、エチレンジアミン四酢酸・一無水物（ＥＤＴＡ・一無水物）、ジエチレントリアミン五酢酸・二無水物（ＤＴＰＡ・二無水物）、ジエチレントリアミン五酢酸・一無水物（ＤＴＰＡ・一無水物）等が例示されるが、中でも特に好ましいのは、ＮＴＡ無水物、ＥＤＴＡ・二無水物、ＤＴＰＡ・二無水物である。
【００２７】
そして、これらの酸無水物と、分子中に反応性官能基を有する前記繊維とを、Ｎ，Ｎ’−ジメチルホルムアミドやジメチルスルホキシド等の極性溶媒中で、例えば６０〜１００℃程度で３０分〜数時間程度反応させると、酸無水物基が繊維分子中の反応性官能基（例えば水酸基やアミノ基など）と反応して結合し、前記一般式［１］で示されるアシル基がペンダント状に導入され、金属イオンに対して選択的吸着性に優れた繊維を得ることができる。
【００２８】
繊維を構成する分子中に反応性官能基が存在しない場合は、該繊維を酸化、グラフト重合など任意の手段で反応性官能基を導入してから、前記ポリカルボン酸の無水物を反応させればよく、また反応性官能基が存在する場合でも、上記ポリカルボン酸の無水物との反応性が低い場合は、反応性の高い反応性官能基を導入してから前記ポリカルボン酸無水物と反応させることも有効である。
【００２９】
かくして得られる金属キレート形成能を有する繊維における、上記アシル基の導入量は、上記導入反応に使用する上記ポリカルボン酸無水物の使用量や反応条件等によって任意に調整することができるが、十分な重金属捕捉能を与えるには、前記式によって計算されるポリカルボン酸無水物の置換率を１０重量％以上、より好ましくは２０重量％以上にすることが望ましい。置換率の上限は特に制限されないが、置換率が高くなりすぎると、繊維の結晶性が高くなって脆弱になる傾向が現れてくるので、経済性なども考慮して１００重量％程度以下、より一般的には５０重量％程度以下に抑えるのがよい。但し、繊維分子中の反応性官能基の種類や導入量によっては、１００〜２００重量％といった高レベルの置換率を与えることも可能であり、その様に置換率が非常に高く、従って金属イオン捕捉性能の著しく高められた繊維も、用途によっては極めて有用となる。
【００３０】
上記アシル基の導入反応を、綿あるいは絹とエチレンジアミン四酢酸・二無水物との反応を例にとって模式的に示すと、下記の通りである。
【００３１】
（綿の場合）
【００３２】
【化５】

【００３３】
（絹の場合）
【００３４】
【化６】

【００３５】
尚上記では、繊維分子中の水酸基またはアミノ基に前記ポリカルボン酸無水物を反応させた場合を代表的に示したが、＝ＮＨ，−ＳＨその他の反応性官能基を利用して前記アシル基を導入する場合も、同様に考えればよい。
【００３６】
かくして、繊維分子中に前記一般式［１］で示されるアシル基を導入することによって、中性付近はもとより低ｐＨ域においても、また金属イオン濃度の低い被処理水に適用した場合でも、優れた重金属イオン選択吸着活性を示し、優れた捕捉効果を得ることができる。
【００３７】
また、本発明の金属キレート形成能を有する繊維によって吸着・捕捉された金属は、たとえば塩酸や硫酸等の強酸水溶液で処理すると、前記アシル基中のカルボキシル基から簡単に離脱するので、こうした特性を利用すれば容易に再生することができ、必要によっては再生液から金属を有価金属として回収することも可能となる。
【００３８】
上記金属キレート形成性繊維を用いた捕捉対象となる金属としては、銅、ニッケル、コバルト、亜鉛、カルシウム、マグネシウム、鉄など、または希土類元素であるスカンジウム、イットリウム、およびランタノイド系に属するランタン、セリウム、プラセオジム、ネオジム、サマリウム、ユウロピウム、ガドリウム、ジスプロシウム、ホルミウム、エルビウム、イッテルビウムなど、更には放射性元素であるテクネチウム、プロメチウム、フランシウム、ラジウム、ウラン、プルトニウム、セシウムなどが例示される。
【００３９】
本発明で使用する上記金属キレート形成性繊維は、用いるベース繊維の性状に応じてモノフィラメント状、マルチフィラメント状、紡績糸状、不織布状、繊維織・編物状、紐状、更には紙など任意の性状のものとして得ることができるが、いずれにしても細径の繊維の分子表面に導入された前述の金属キレート形成性を有する基の実質的に全てが、金属捕捉性能を有効に発揮するので、従来の粒状形態のものに比べて格段に優れた金属捕捉能を発揮する。
【００４０】
従って、この金属キレート形成性繊維をフィルターのフィルター素材として使用し、同時に除去すべき不溶性夾雑物の大きさに応じた網目サイズのフィルター層を形成すれば、被処理液が該フィルター層を通過する際に、該被処理液中に含まれる金属イオンがキレート形成性官能基によって捕捉されると共に、不溶性夾雑物は該フィルターの網目によって通過を阻止され、処理液から同時に除去されて清浄化される。
【００４１】
尚フィルターの構成自体は格別特殊なものではなく、その用途に応じて前記キレート形成性繊維を一部もしくは全構成素材として使用し、任意の繊維間隙間を有する織・編物もしくは不織布からなる単層もしくは複層構造のマット状に成形して適当な支持体に組み付けた構造、あるいは通液性支持筒の外周側にキレート形成繊維からなる紐状物を綾巻状に複数層巻回した構造、または同繊維からなる織・編物もしくは不織布シートをプリーツ状に折り曲げて支持部材に装着した構造、同繊維を用いて作製した織・編物や不織布を袋状に成形したバグフィルタータイプなど、公知の全てのフィルターと同様に成形できる。
【００４２】
このとき、使用するキレート形成性繊維の太さや織・編密度、積層数や積層密度などを調整し、また紐状のキレート形成性繊維を複数層に巻回してフィルターとする場合は、巻回の密度や層厚、巻回張力などを調整することによって、繊維間隙間を任意に調整できるので、被処理液体中に混入している不溶性夾雑物の粒径に応じて該繊維間隙間を調整すれば、必要に応じた清浄化性能のフィルターを得ることができる。
【００４３】
なお本発明のフィルターは、フィルター素材の全てを前記キレート形成性繊維で構成し、フィルター層全体に類金属イオンと不溶性夾雑物に対する除去性能を与えることができるが、本発明のキレート形成性繊維は通常のフィルター素材に比べて高価であるので、被処理液体中に含まれる金属イオンと不溶性夾雑物の含有比率に応じて、キレート形成性繊維と通常の濾過用フィルター素材を適当な比率で組み合わせ（混紡、混織・混編、積層など）、比較的低コストで高い清浄化効果が得られる様にすることも可能である。
【００４４】
また、本発明で使用する金属キレート形成性繊維は通常のフィルター素材に比べて高価であるので、好ましくは被処理液体中の不溶性夾雑物の大部分を適当な手段で予め除去しておき、その後で金属キレート形成性繊維層を通すことによって、残りの不溶性夾雑物と金属イオンを同時に除去することが望ましい。
【００４５】
また該フィルターの作製に当たっては、前述した様な方法によって作製した金属キレート形成性繊維よりなる不織布、織・編物、紐などをフィルター内に組み込むことも勿論可能であるが、金属キレート形成性化合物との反応性官能基を有する基を有し（あるいは導入された）繊維をフィルター素材として組み込んだフィルターに、金属キレート形成性化合物含有液を循環させ、該フィルター素材に金属キレート形成性官能基を事後的に導入することによって、キレート捕捉能を与えることも可能である。従って、例えばセルロース等をフィルター構成素材とする通常のフィルターを使用し、これに金属キレート形成性官能基を導入することによって、金属イオン除去性能を兼ね備えた本発明のフィルターとすることもできる。
【００４６】
本発明は以上の様に構成されており、フィルター素材としてキレート形成性繊維を使用することにより、次の様な利点を享受できる。
【００４７】
▲１▼従来の粒状キレート樹脂には、キレート捕捉に機能する部位として外周面と細孔部があるが、細孔部は拡散が遅くて実質的に全官能基がキレート捕捉に寄与し得ないので、キレート樹脂全体としては有効活用率が極めて低く、且つ捕捉し得る元素の絶対量も不十分とならざるを得ず、また不溶性夾雑物に対する除去性能は殆んど期待できないが、本発明のフィルターでは、繊維表面に導入されたキレート形成性官能基の全てが金属成分のキレート捕捉に有効に活用されると共に有効比表面積も大きいので、少量の使用で極めて高いキレート捕捉能が得られると共に、繊維間隙間を調整することによって、被処理液体中の不溶性夾雑物を同時に除去することができ、一回の処理で高い清浄化効果が得られる。
【００４８】
▲２▼キレート形成性官能基がフィルター素材を構成する繊維表面に露出しているので、吸着速度が高い。
【００４９】
▲３▼粒状キレート樹脂は一般に乾燥すると脆弱になって微粉化し、実用できなくなるが、本発明で使用するキレート繊維は、繊維素材にキレート形成性官能基を導入したものであるから、乾燥しても脆化することがなく、再生による繰り返し使用も容易である。
【００５０】
▲４▼粒状キレート樹脂では、充填容器の形状によって使用形態が制限されるが、本発明はキレート形成性繊維をフィルター素材とするものであるから、不織布状や織編物状、紐状などとすることにより、使用目的に応じた任意の形状のフィルターに成形できる。
【００５１】
▲５▼粒状キレート樹脂では、粒径によって空隙率が自動的に決まってくるが、キレート繊維であれば、形態を変えることによって充填密度や繊維間空隙を任意に変更できるので、被処理液体中に含まれる不溶性夾雑物の粒径に応じた高い清浄化効果を確保できる。
【００５２】
▲６▼本発明のフィルターを使用すれば、キレート形成性繊維で金属成分と不溶性夾雑物を捕捉した後、例えば塩酸や硫酸等の強酸水溶液で処理することにより、キレートを形成して捕捉された金属元素を簡単に離脱させることができ、それにより再生液から金属成分を有価成分として回収することも可能となる。
【００５３】
▲７▼本発明で使用する前記のキレート形成性繊維は、特に銅、亜鉛、ニッケル、コバルト等の重金属イオンと選択的にキレートを形成する特性を有しているので、その他の金属イオン、例えばＭｇ，Ｃａ，Ｎａ，Ｋ等の金属、あるいはその他の陰イオン、たとえばフッ素、塩素、沃素等のハロゲンイオン等が共存する場合でも、銅、亜鉛、ニッケル、コバルト等の重金属イオンの選択的捕捉材としても極めて有効に活用することができる。従って、様々の製造工程において、Ｍｇ，Ｃａ，Ｎａ，Ｋなどが含まれる工程液から有害な重金属だけを除去し、あるいは、例えば飲料水や食品加工用水中に含まれることのあるＭｇ，Ｃａ，Ｎａ，Ｋ等を残して有害な重金属のみを除去することも可能である。
【００５４】
かくして本発明のフィルターであれば、構成素材として使用するキレート形成性繊維独自の金属キレート形成能によって金属を効率よく除去できると共に、不溶性夾雑物を同時に除去することができるので、例えば次に示す様な被処理液体の清浄化に有効に活用できる。
【００５５】
ａ．飲料水や食品加工用水の浄化（特に重金属を含む有害イオン性物質と不溶性夾雑物の同時除去）。
【００５６】
ｂ．食用油脂などに含まれることのあるニッケル等の金属イオンと共に不溶性夾雑物の除去。
【００５７】
ｃ．エンジンオイルやモータオイル等の廃油中に金属触媒等とし混入することのある銅、ニッケル等の金属イオンと共に不溶性夾雑物の除去（廃油処理）。
ｄ．超純水製造時における微量重金属と共に不溶性夾雑物の除去。
【００５８】
ｅ．各種有機溶剤や重合性モノマーの製造工程あるいは保存中に不純物などとして混入することのある銅、ニッケル、鉄などの金属イオンと共に不溶性夾雑物の除去。
ｆ．過酸化水素水精製時における微量重金属と共に不溶性夾雑物の除去。
【００５９】
【実施例】
次に本発明の実施例を示すが、本発明はもとより下記実施例によって制限を受けるものではなく、前後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも勿論可能であり、それらはいずれも本発明の技術的範囲に含まれる。
【００６０】
実施例
綿製の紡績糸をステンレス製のコア材に綾巻き状に巻回した市販のカートリッジフィルター（アドバンテック東洋社製、商品名「ＴＣＷ−１−ＣＳＳ」：公称孔径１μｍ）を、ステンレス製ハウジング（アドバンテック東洋社製、商品名「１ＴＳ」）に装着し、これに、エチレンジアミン四酢酸・２無水物１７７ｇをＮ，Ｎ’−ジメチルホルムアミド１０００ｍｌに８０℃で加熱溶解した溶液を、循環ポンプを用いて１５リットル／分の流速で８０℃×６時間循環させた。次いで反応液を排出した後、蒸留水３０００ｍｌを循環させながら、アンモニア水を用いてｐＨを約１０に調整してから約１時間循環することにより、未反応のエチレンジアミン四酢酸を溶解し、更に蒸留水を用いて洗浄水が中性になるまで循環・排液を繰り返した。その後、０．１規定の硫酸水溶液３０００ｍｌを１時間循環した後、蒸留水を用いて洗浄水が中性になるまで循環・排液を繰り返し、金属キレート形成性フィルターを得た。
【００６１】
この金属キレート形成性フィルターを、ポリプロピレン製ハウジング（アドバンテック東洋社製商品名「１ＰＰ−１−０００」）に装着し、Ｃｕ，Ｚｎ，Ｎｉ，Ｃｏを各々約５０ｐｐｍを含有し、ｐＨ５に調製した希硫酸水溶液１０リットルに、不溶性夾雑物として平均粒径１０μｍの二酸化珪素微粉末２．２１ｇを分散させた試験液を、１５リットル／分の流速で２５℃で３０分間循環させた。
【００６２】
その後、試験液中に残存したＣｕ²⁺，Ｚｎ²⁺，Ｎｉ²⁺，Ｃｏ²⁺の各金属イオン濃度を定量したところ、いずれも１ｐｐｍ以下となっていることが確認された。また、該試験液１リットルを孔径０．１μｍのメンブランフィルターに通し、残存する二酸化珪素を定量することによってその除去率を求めたところ、９８％であることが確認された。
【００６３】
実施例２
上記実施例１において、エチレンジアミン四酢酸・２無水物に代えてニトリロ三酢酸・無水物１７７ｇを使用した以外は実施例１と同様にして、金属キレート形成性フィルターを得た。得られた金属キレート形成性フィルターを用いて実施例１と同様の試験を行なったところ、Ｃｕ²⁺，Ｚｎ²⁺，Ｎｉ²⁺，Ｃｏ²⁺の各金属イオン濃度はいずれも１ｐｐｍ以下となっており、二酸化珪素の除去率は９８％であることが確認された。
【００６４】
実施例３
上記実施例１において、綿製の紡績糸をステンレス製のコア材に綾巻き状に巻回したカートリッジフィルターに代えて、セルロース繊維ろ紙をプリーツ状に成形したカートリッジフィルター（アドバンテック東洋社製商品名「ＴＣ−１」：公称孔径１μｍ）を使用した以外は実施例１と同様にして、金属キレート形成性フィルターを得た。得られた金属キレート形成性フィルターを用いて実施例１と同様の試験を行なったところ、Ｃｕ²⁺，Ｚｎ²⁺，Ｎｉ²⁺，Ｃｏ²⁺の各金属イオン濃度はいずれも１ｐｐｍ以下となっており、二酸化珪素の除去率は９７％であることが確認された。
【００６５】
実施例４
上記実施例１と同様にして得た金属キレート形成性フィルターを、ステンレス製ハウジング（アドバンテック東洋社製、商品名「１ＴＳ」）に装着し、Ｎｉを１３００ｐｐｂ，Ｃｕを３０ｐｐｂ，Ｆｅを４６０ｐｐｂ含有するパーム硬化油２リットルを６０℃に加温して融かし、更に不溶性夾雑物として平均粒径１０μｍの二酸化珪素微粉末０．５１ｇを分散させた試験液を、１リットル／分の流速で６０℃で５分間循環させた。
【００６６】
その後、パーム油中の各金属残存量を測定したところ、Ｎｉは１０ｐｐｂ以下、ＣｕとＦｅはいずれも５ｐｐｂ以下に低減していた。また、該試験液５００ｍｌをトリクロルエチレンで希釈した後、孔径０．１μｍのメンブレンフィルターに通し、残存する二酸化珪素量を定量することによってその除去率を求めたところ、９４％であることが確認された。
【００６７】
【発明の効果】
本発明は以上の様に構成されており、フィルター素材として金属成分に対して高い捕捉能を有し且つ不溶夾雑物除去性能を兼ね備えた金属キレート捕捉性繊維を使用することによって、被処理液体中の金属成分、特に銅、亜鉛、ニッケル、コバルト、鉄などと不溶性夾雑物を同時に除去することができ、それらの清浄化を極めて効率よく行なうことができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel filter capable of efficiently removing and cleaning metal ions and insoluble impurities in an untreated liquid, and a liquid cleaning method using the filter. It can efficiently remove metal ions contained in aqueous and oily liquids, especially harmful heavy metal ions such as copper, zinc, nickel and cobalt, and at the same time remove insoluble impurities contained in these liquids to be treated. Therefore, it can be effectively used for purification of water such as industrial wastewater, drinking water, and water for food processing, or oil such as edible oil and food processing oil.
[0002]
[Prior art]
Industrial wastewater and the like may contain various harmful ions. From the viewpoint of preventing environmental pollution, these harmful metal ions are required to be sufficiently removed by waste water treatment. In addition, heavy metal components contained in rivers and groundwater also have an adverse effect on the human body, so sufficient consideration must be given to the effective use of water. Furthermore, it is necessary to remove as much as possible metals that may be mixed in as a hydrogenation catalyst or the like when producing edible oil or food processing oil.
[0003]
In addition, when used as irrigation water, food processing water, edible oil, food processing oil, etc., it is necessary to remove insoluble impurities in addition to the metal components as described above, but these can be removed at the same time. No device has been proposed.
[0004]
The present invention efficiently removes these harmful metal ions and their compounds from a liquid to be treated such as water or edible oil, and at the same time efficiently removes and purifies insoluble impurities contained in the liquid to be treated. Furthermore, the present invention provides a filter capable of cleaning the liquid to be treated such as water and oil using the filter.
[0005]
Conventionally, ion exchange resins have been widely used to remove harmful metal ions in effluent or to capture beneficial metal ions, but the effect of selectively adsorbing and separating low-concentration metal ions can always be satisfactory. Not a thing.
[0006]
In addition, chelate resins that have the property of selectively capturing these by forming chelates with metal ions have excellent selective capture properties for metal ions, particularly heavy metal ions. It is used to remove and capture heavy metals in the processing field. However, most of the chelate resins are simply those in which iminodiacetic acid is introduced, have a low chelate-forming ability, and lack the selective adsorptivity particularly in the pH range.
[0007]
In general, ion-exchange resins and chelate-forming resins are in the form of beads with a rigid three-dimensional structure provided by a crosslinking agent such as divinylbenzene, and the diffusion rate of metal ions and regenerants into the resin is slow. There was also a problem with efficiency. Furthermore, in the case of a disposable type that is not recycled, it is difficult to incinerate, so how to reduce the volume of used resin also becomes a big problem.
[0008]
As a means for solving such problems of the bead-like chelate-forming resin, a fibrous or sheet-like chelate material has been proposed (Japanese Patent Laid-Open No. 7-10925). This fiber-like or sheet-like chelate material has a large specific surface area and has chelating functional groups that serve as adsorption / desorption points for metal ions on the surface, so the adsorption / desorption efficiency is improved, and incineration is also possible. It has many advantages such as being easy to do. However, the production method of the fibrous or sheet-like chelate material is complicated, and a method using ionizing radiation has to be adopted, so that there are many in terms of equipment, safety, production cost, etc. The problem is pointed out.
[0009]
Furthermore, conventional chelate resins or fibrous or sheet-like chelate materials exhibit a certain level of metal ion scavenging ability as described above, but are expected to be removed from insoluble contaminants that are mixed in the liquid to be treated. Therefore, in order to remove these insoluble contaminants and sufficiently clean the liquid to be treated, the insoluble impurities in the liquid to be treated must be removed before or after the removal of metal ions with a chelate resin or the like. In order to obtain a reliable cleaning effect, at least two processes are required.
[0010]
[Problems to be solved by the invention]
The present invention has been made paying attention to the circumstances as described above, and its first object is that it has excellent capture performance for metal ions and their compounds, and is easy to incinerate. In addition, we developed chelate-forming fibers that can be manufactured inexpensively by a simple and safe method, and by taking advantage of the special properties of the chelate fibers, metal ions and insoluble contaminants in the liquid to be treated can be efficiently and efficiently used simultaneously. The object of the present invention is to provide a filter that can be removed, and to establish a method capable of efficiently cleaning a liquid using the filter.
[0011]
[Means for Solving the Problems]
The filter according to the present invention that has solved the above problems is a chelate-forming fiber in which a group having an acyl group represented by the following general formula [1] is introduced into a fiber molecule as at least a part of a filter material. There is a gist where it is arranged.
[0012]
[Chemical 3]

[0013]
(Wherein R ¹ , R ² and R ³ are lower alkylene groups, and n represents an integer of 1 to 4)
[0014]
The chelate-forming fiber which is the main component of the filter is introduced directly into the reactive functional group of the molecule constituting the base fiber, or after introducing another reactive functional group into the molecule constituting the fiber, and then into the functional group. What was obtained by making the acid anhydride of polycarboxylic acid shown by the following general formula [2] react is preferably used,
[0015]
[Formula 4]

[0016]
(Wherein R ¹ , R ² and R ³ are lower alkylene groups, and n represents an integer of 1 to 4)
[0017]
In order to enhance the metal ion capturing ability, it is desirable to use a chelate-forming fiber having a substitution rate calculated by the following formula of the acyl group of 10% by weight or more.
Substitution rate (% by weight) = [(fiber weight after reaction−fiber weight before reaction) / fiber weight before reaction] × 100
[0018]
The acid anhydride of the polycarboxylic acid represented by the general formula [2] used when producing the chelate-forming fiber includes nitrilotriacetic anhydride, ethylenediaminetetraacetic acid dianhydride, diethylenetriaminepentaacetic acid. At least one selected from the group consisting of dianhydrides is preferred, and as the base fiber into which these chelate-forming functional groups are introduced, natural fibers, regenerated fibers, and synthetic fibers may be used alone, or two or more if necessary. Can be used in combination.
[0019]
Further, the cleaning method according to the present invention is characterized in that a liquid such as an aqueous liquid or an oily liquid is passed through the above-described filter, and metal ions and insoluble impurities in the liquid are removed and cleaned. .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the metal chelate-forming fiber as the constituent material of the filter according to the present invention has an acyl group represented by the general formula [1] as a substituent in the fiber molecule. Since nitrogen and carboxylic acid present therein have excellent selective adsorption properties for heavy metal ions such as copper, zinc, nickel, cobalt, and the selective adsorption active groups are exposed on the fiber surface, This fiber exhibits excellent metal ion selective adsorption activity due to the presence of the acyl group.
[0021]
The lower alkylene group represented by R ^{1 to} R ³ in the general formula [1] includes a C _{1 to} C ₆ alkylene group, and particularly preferred are methylene, ethylene and propylene. The number of repeats n is particularly preferably 1 or 2.
[0022]
The type of base fiber to which metal chelate-forming ability is imparted is not particularly limited, and various plant fibers such as cotton and linen; various animal fibers such as silk and wool; viscose rayon, Various regenerated fibers including acetate, etc .; various synthetic fibers including polyamide, acrylic, polyester, etc. can be used, and these fibers are variously modified as required. It doesn't matter.
[0023]
Among these base fibers, particularly preferred are plant fibers, animal fibers, and regenerated fibers having a reactive functional group such as hydroxyl group or amino group in the fiber molecule. It is preferable because a group having the ability to form a metal chelate as described above can be easily introduced using the reactive functional group therein. However, even if the raw fiber itself does not have a reactive functional group, it is modified by any means such as oxidation to introduce a reactive functional group, and this functional group is used as described above. It is also possible to introduce various groups.
[0024]
The properties of the fibers used here are not particularly limited, and may be multifilaments of long fibers, spun yarns of short fibers, or a fabric obtained by weaving or knitting these in a woven or knitted shape, or a non-woven fabric. Of course, it is also effective to use a fiber or a woven / knitted fabric obtained by compounding or blending two or more kinds of fibers. It is also possible to use wood pulp, paper, wood pieces, wood chips, thin plates and the like.
[0025]
When the fiber having the reactive functional group in the molecule is reacted with the acid anhydride of the polycarboxylic acid represented by the general formula [2], the fiber molecule is represented by the general formula [1]. The acyl group is introduced in a pendant form, and the carboxylic acid in the acyl group has a very high chelate reactivity with the metal ion, and therefore the liquid to be treated containing the metal ion using the fiber into which the acyl group is introduced. , The metal ions contained therein are efficiently trapped by forming a metal chelate.
[0026]
Preferable specific examples of the acid anhydride of the polycarboxylic acid represented by the general formula [2] used for the introduction of the acyl group represented by the general formula [1] include nitrilotriacetic acid / anhydride (NTA anhydride). ), Ethylenediaminetetraacetic acid / dianhydride (EDTA / dianhydride), ethylenediaminetetraacetic acid / monoanhydride (EDTA / monoanhydride), diethylenetriaminepentaacetic acid / dianhydride (DTPA / dianhydride), diethylenetriaminepentaacetic acid -Although monoanhydride (DTPA * monoanhydride) etc. are illustrated, NTA anhydride, EDTA * dianhydride, DTPA * dianhydride are especially preferable especially.
[0027]
Then, these acid anhydrides and the above-mentioned fibers having a reactive functional group in the molecule are mixed in a polar solvent such as N, N′-dimethylformamide or dimethyl sulfoxide, for example, at about 60 to 100 ° C. for 30 minutes to When reacted for several hours, the acid anhydride group reacts with and binds to a reactive functional group (for example, a hydroxyl group or an amino group) in the fiber molecule, and the acyl group represented by the general formula [1] is formed in a pendant shape. Introduced, a fiber excellent in selective adsorptivity to metal ions can be obtained.
[0028]
If there is no reactive functional group in the molecule constituting the fiber, the reactive of the fiber can be introduced by any means such as oxidation or graft polymerization, and then the anhydride of the polycarboxylic acid can be reacted. Even if a reactive functional group is present, if the reactivity with the polycarboxylic acid anhydride is low, a highly reactive reactive functional group is introduced before the polycarboxylic acid anhydride and It is also effective to react.
[0029]
The amount of the acyl group introduced in the thus-obtained metal chelate-forming fiber can be arbitrarily adjusted depending on the amount of polycarboxylic anhydride used in the introduction reaction, reaction conditions, etc. In order to provide a heavy metal scavenging ability, it is desirable that the substitution rate of the polycarboxylic acid anhydride calculated by the above formula is 10 wt% or more, more preferably 20 wt% or more. The upper limit of the substitution rate is not particularly limited, but if the substitution rate becomes too high, the fiber crystallinity tends to increase and becomes brittle. Generally, it is better to keep it to about 50% by weight or less. However, depending on the type and amount of the reactive functional group in the fiber molecule, it is possible to give a high substitution rate of 100 to 200% by weight, and the substitution rate is very high. Fibers with significantly enhanced capture performance are also very useful depending on the application.
[0030]
The introduction reaction of the acyl group is schematically shown below, taking cotton or silk and ethylenediaminetetraacetic acid / dianhydride as an example.
[0031]
(For cotton)
[0032]
[Chemical formula 5]

[0033]
(For silk)
[0034]
[Chemical 6]

[0035]
In the above, the case where the polycarboxylic acid anhydride is reacted with the hydroxyl group or amino group in the fiber molecule is representatively shown. However, the acyl group is used by utilizing = NH, -SH or other reactive functional groups. The same applies to the introduction of.
[0036]
Thus, by introducing the acyl group represented by the general formula [1] into the fiber molecule, it is excellent not only in the vicinity of neutrality but also in a low pH range and when applied to treated water with a low metal ion concentration. The heavy metal ion selective adsorption activity is exhibited, and an excellent capturing effect can be obtained.
[0037]
In addition, when the metal adsorbed and captured by the fiber having the metal chelate-forming ability of the present invention is treated with a strong acid aqueous solution such as hydrochloric acid or sulfuric acid, for example, it is easily released from the carboxyl group in the acyl group. If used, it can be easily regenerated, and if necessary, the metal can be recovered from the regenerated solution as a valuable metal.
[0038]
Examples of metals to be captured using the metal chelate-forming fibers include copper, nickel, cobalt, zinc, calcium, magnesium, iron, etc., or rare earth elements scandium, yttrium, and lanthanum, cerium belonging to the lanthanoid series, Examples include praseodymium, neodymium, samarium, europium, gadolinium, dysprosium, holmium, erbium, ytterbium, and the like, and technetium, promethium, francium, radium, uranium, plutonium, cesium, and the like.
[0039]
The metal chelate-forming fiber used in the present invention has any properties such as monofilament, multifilament, spun yarn, non-woven fabric, fiber woven / knitted fabric, string, and paper depending on the properties of the base fiber used. However, in any case, substantially all of the aforementioned metal chelate-forming groups introduced on the molecular surface of the small-diameter fiber effectively exhibit the metal-trapping performance. Compared to conventional granular forms, it exhibits much better metal capture capability.
[0040]
Therefore, if this metal chelate-forming fiber is used as a filter material for a filter and a filter layer having a mesh size corresponding to the size of insoluble contaminants to be removed at the same time, the liquid to be treated passes through the filter layer. At this time, the metal ions contained in the liquid to be treated are trapped by the chelate-forming functional group, and the insoluble contaminants are prevented from passing by the network of the filter, and are simultaneously removed from the treatment liquid and cleaned. .
[0041]
The filter structure itself is not particularly special, depending on its use, the chelate-forming fiber is used as a part or all of the constituent material, and a single layer composed of a woven / knitted or non-woven fabric having an arbitrary inter-fiber gap. Or a structure formed into a mat with a multi-layer structure and assembled to an appropriate support, or a structure in which a cord-like material made of a chelate-forming fiber is wound in a spiral pattern on the outer peripheral side of a liquid-permeable support tube, Or all known structures such as a woven / knitted or non-woven sheet made of the same fiber folded into a pleated shape and attached to a support member, and a woven / knitted or non-woven fabric made using the same fiber formed into a bag shape. Can be molded in the same way as the filter
[0042]
At this time, when adjusting the thickness, woven / knitting density, the number of layers, the lamination density, etc. of the chelate-forming fibers to be used and winding the string-like chelate-forming fibers into a plurality of layers to form a filter, By adjusting the density, layer thickness, winding tension, etc., the inter-fiber gap can be adjusted arbitrarily, so that the inter-fiber gap is adjusted according to the particle size of the insoluble contaminants mixed in the liquid to be treated. Then, a filter having a cleaning performance as required can be obtained.
[0043]
In the filter of the present invention, all of the filter material is composed of the chelate-forming fiber, and the entire filter layer can be given removal performance against similar metal ions and insoluble contaminants. Since it is more expensive than ordinary filter materials, chelate-forming fibers and ordinary filtration filter materials are combined at an appropriate ratio according to the content ratio of metal ions and insoluble impurities contained in the liquid to be treated ( It is also possible to obtain a high cleaning effect at a relatively low cost.
[0044]
In addition, since the metal chelate-forming fiber used in the present invention is more expensive than a normal filter material, it is preferable to remove most of insoluble impurities in the liquid to be treated in advance by an appropriate means, and then It is desirable to remove the remaining insoluble impurities and metal ions simultaneously by passing the metal chelate-forming fiber layer.
[0045]
In producing the filter, it is of course possible to incorporate a non-woven fabric, woven / knitted fabric, string, etc. made of a metal chelate-forming fiber produced by the method as described above into the filter. A metal chelate-forming compound-containing liquid is circulated through a filter incorporating a fiber having a reactive functional group (or introduced) as a filter material, and the metal chelate-forming functional group is subsequently added to the filter material. It is also possible to give chelate scavenging ability by introducing it. Therefore, for example, an ordinary filter using cellulose or the like as a filter constituent material is used, and by introducing a metal chelate-forming functional group into the filter, the filter of the present invention having metal ion removal performance can be obtained.
[0046]
This invention is comprised as mentioned above and can enjoy the following advantages by using chelate-forming fiber as a filter material.
[0047]
(1) The conventional granular chelate resin has an outer peripheral surface and pores as sites that function for chelate capture, but the pores are slow to diffuse and virtually all functional groups cannot contribute to chelate capture. Therefore, the effective utilization rate of the chelate resin as a whole is extremely low, the absolute amount of elements that can be captured must be insufficient, and the removal performance for insoluble contaminants can hardly be expected. In the filter, all of the chelate-forming functional groups introduced on the fiber surface are effectively utilized for chelate capture of metal components and the effective specific surface area is also large, so extremely high chelate capture ability can be obtained with a small amount of use, By adjusting the inter-fiber gap, insoluble impurities in the liquid to be treated can be removed at the same time, and a high cleaning effect can be obtained by a single treatment.
[0048]
(2) Since the chelate-forming functional group is exposed on the surface of the fibers constituting the filter material, the adsorption rate is high.
[0049]
(3) The granular chelate resin generally becomes brittle and finely pulverized when dried, making it impractical. However, the chelate fiber used in the present invention has a chelate-forming functional group introduced into the fiber material. Are not brittle and can be used repeatedly by regeneration.
[0050]
(4) The usage of the granular chelate resin is limited depending on the shape of the filled container, but since the present invention uses chelate-forming fibers as a filter material, it is made into a nonwoven fabric, woven or knitted fabric, string, etc. Therefore, it can be formed into a filter having an arbitrary shape according to the purpose of use.
[0051]
(5) In granular chelate resins, the porosity is automatically determined by the particle size, but in the case of chelate fibers, the packing density and inter-fiber voids can be changed arbitrarily by changing the form, so A high cleaning effect according to the particle size of the insoluble contaminants contained in can be ensured.
[0052]
(6) If the filter of the present invention is used, the metal component and insoluble impurities are captured by the chelate-forming fiber, and then treated with a strong acid aqueous solution such as hydrochloric acid or sulfuric acid to form a chelate and be captured. The metal element can be easily detached, and it is possible to recover the metal component as a valuable component from the regenerated liquid.
[0053]
(7) The chelate-forming fiber used in the present invention has a characteristic of selectively forming a chelate with heavy metal ions such as copper, zinc, nickel, cobalt and the like. Selective trapping materials for heavy metal ions such as copper, zinc, nickel and cobalt even when metals such as Mg, Ca, Na and K, or other anions such as halogen ions such as fluorine, chlorine and iodine coexist As such, it can be used extremely effectively. Accordingly, in various manufacturing processes, only harmful heavy metals are removed from the process liquid containing Mg, Ca, Na, K, or the like, or Mg, Ca, which may be contained in drinking water or food processing water, for example. It is also possible to remove only harmful heavy metals while leaving Na, K and the like.
[0054]
Thus, with the filter of the present invention, the metal can be efficiently removed and the insoluble contaminants can be removed at the same time by the unique metal chelate-forming ability of the chelate-forming fiber used as the constituent material. Can be effectively used to clean the liquid to be treated.
[0055]
a. Purification of drinking water and food processing water (especially simultaneous removal of harmful ionic substances including heavy metals and insoluble impurities).
[0056]
b. Removal of insoluble impurities together with metal ions such as nickel that may be contained in edible oils and fats.
[0057]
c. Removal of insoluble contaminants along with metal ions such as copper and nickel, which can be mixed in waste oil such as engine oil and motor oil as metal catalyst.
d. Removal of insoluble impurities as well as trace heavy metals during ultrapure water production.
[0058]
e. Removal of insoluble impurities together with metal ions such as copper, nickel and iron that may be mixed as impurities during the manufacturing process or storage of various organic solvents and polymerizable monomers.
f. Removal of insoluble contaminants along with trace heavy metals during hydrogen peroxide purification.
[0059]
【Example】
Next, examples of the present invention will be shown. However, the present invention is not limited by the following examples as a matter of course, and it is needless to say that the present invention can be implemented with appropriate modifications within a range that can meet the gist of the preceding and following descriptions. These are all included in the technical scope of the present invention.
[0060]
EXAMPLE A commercially available cartridge filter (advantech Toyo Co., Ltd., trade name “TCW-1-CSS”: nominal pore diameter 1 μm) in which a cotton spun yarn is wound around a stainless steel core material in a twilled form is made into a stainless steel housing. (Product name “1TS”, manufactured by Advantech Toyo Co., Ltd.), and a solution obtained by dissolving 177 g of ethylenediaminetetraacetic acid dianhydride in 1000 ml of N, N′-dimethylformamide at 80 ° C. using a circulation pump And circulated at 80 ° C. for 6 hours at a flow rate of 15 liters / minute. Next, after discharging the reaction liquid, adjusting the pH to about 10 using ammonia water while circulating 3000 ml of distilled water, and circulating for about 1 hour to dissolve unreacted ethylenediaminetetraacetic acid and further distill Circulation and drainage were repeated using water until the wash water became neutral. Thereafter, 3000 ml of 0.1 N sulfuric acid aqueous solution was circulated for 1 hour, and then circulation and drainage were repeated using distilled water until the wash water became neutral, to obtain a metal chelate-forming filter.
[0061]
This metal chelate-forming filter was mounted on a polypropylene housing (trade name “1PP-1-000” manufactured by Advantech Toyo Co., Ltd.), containing about 50 ppm each of Cu, Zn, Ni, and Co, and adjusted to pH 5 A test solution in which 2.21 g of silicon dioxide fine powder having an average particle size of 10 μm was dispersed as an insoluble contaminant in 10 liters of sulfuric acid aqueous solution was circulated at 25 ° C. for 30 minutes at a flow rate of 15 liters / minute.
[0062]
Thereafter, the concentrations of each metal ion of Cu ²⁺ , Zn ²⁺ , Ni ²⁺ , and Co ²⁺ remaining in the test solution were quantified, and it was confirmed that all were 1 ppm or less. Further, when 1 liter of the test solution was passed through a membrane filter having a pore diameter of 0.1 μm and the remaining silicon dioxide was quantified, the removal rate was determined to be 98%.
[0063]
Example 2
A metal chelate-forming filter was obtained in the same manner as in Example 1, except that 177 g of nitrilotriacetic acid / anhydride was used instead of ethylenediaminetetraacetic acid · 2 anhydride. When the same test as in Example 1 was performed using the obtained metal chelate-forming filter, the concentration of each metal ion of Cu ²⁺ , Zn ²⁺ , Ni ²⁺ , and Co ²⁺ was 1 ppm or less. The removal rate of silicon dioxide was confirmed to be 98%.
[0064]
Example 3
In Example 1 above, instead of a cartridge filter in which a cotton spun yarn is wound around a stainless steel core material in a twill shape, a cartridge filter in which cellulose fiber filter paper is formed into a pleated shape (trade name “Advantech Toyo” A metal chelate-forming filter was obtained in the same manner as in Example 1 except that “TC-1”: nominal pore diameter 1 μm) was used. When the same test as in Example 1 was performed using the obtained metal chelate-forming filter, the concentration of each metal ion of Cu ²⁺ , Zn ²⁺ , Ni ²⁺ , and Co ²⁺ was 1 ppm or less. The removal rate of silicon dioxide was confirmed to be 97%.
[0065]
Example 4
A metal chelate-forming filter obtained in the same manner as in Example 1 above is mounted on a stainless steel housing (trade name “1TS”, manufactured by Advantech Toyo Co., Ltd.), and contains 1300 ppb Ni, 30 ppb Cu, and 460 ppb Fe. A test solution in which 2 liters of hydrogenated oil was heated to 60 ° C. and melted, and 0.51 g of silicon dioxide fine powder having an average particle size of 10 μm was dispersed as an insoluble contaminant at a flow rate of 1 liter / min at 60 ° C. For 5 minutes.
[0066]
Then, when each metal residual amount in palm oil was measured, Ni was reduced to 10 ppb or less, and both Cu and Fe were reduced to 5 ppb or less. In addition, after diluting 500 ml of the test solution with trichloroethylene, it was passed through a membrane filter having a pore diameter of 0.1 μm, and the removal rate was determined by quantifying the amount of remaining silicon dioxide, which was confirmed to be 94%. It was.
[0067]
【The invention's effect】
The present invention is configured as described above, and uses a metal chelate-capturing fiber that has a high scavenging ability for a metal component and also has an insoluble contaminant removal performance as a filter material. The metal components, particularly copper, zinc, nickel, cobalt, iron and the like, and insoluble impurities can be removed at the same time, and they can be cleaned very efficiently.

Claims (7)

As at least a part of the filter material, a chelate-forming fiber in which a group having an acyl group represented by the following general formula [1] is introduced into at least one fiber molecule selected from natural fibers and regenerated fibers is disposed. A filter characterized by

(Wherein R ¹ , R ² and R ³ are lower alkylene groups, and n represents an integer of 1 to 4) The chelate-forming fiber is directly or directly introduced into the reactive functional group of the molecule constituting the fiber, and then the functional group is represented by the following general formula [2]. The filter according to claim 1, wherein the filter is obtained by reacting a polycarboxylic acid anhydride.

(Wherein R ¹ , R ² and R ³ are lower alkylene groups, and n represents an integer of 1 to 4) The filter according to claim 2, wherein the substitution rate calculated by the following formula of the acyl group is 10% by weight or more.
Substitution rate (% by weight) = [(fiber weight after reaction−fiber weight before reaction) / fiber weight before reaction] × 100   The polycarboxylic acid anhydride represented by the general formula [2] is at least one selected from the group consisting of nitrilotriacetic anhydride, ethylenediaminetetraacetic acid dianhydride, and diethylenetriaminepentaacetic acid dianhydride. Item 4. The filter according to any one of Items 1 to 3. Passed through a liquid filter according to any of claims 1 to 4, the cleaning method of the liquid and removing the metal ions and insoluble impurities in the liquid. The cleaning method according to claim 5 , wherein the liquid is an aqueous liquid. The cleaning method according to claim 5 , wherein the liquid is an oily liquid.