JP4383069B2

JP4383069B2 - Spherical activated carbon for direct perfusion of blood and method for producing the same

Info

Publication number: JP4383069B2
Application number: JP2003046439A
Authority: JP
Inventors: 秀明佐藤; 丈樹小野; 直弘園部
Original assignee: Kureha Corp
Current assignee: Kureha Corp
Priority date: 2003-02-24
Filing date: 2003-02-24
Publication date: 2009-12-16
Anticipated expiration: 2023-02-24
Also published as: JP2004256324A

Description

【０００１】
【発明の属する技術分野】
本発明は、血液の直接灌流用球状活性炭及びその製造方法に関する。
【０００２】
【従来の技術】
腎疾患患者などの血液中に含まれる毒性物質を除去する目的で、患者の体外に血液循環路を形成し、患者の血液を体内から体外へ取り出し、体外での浄化処理を実施してから、再び患者体内へ血液を戻す治療方法がある。こうした血液浄化の代表的手段としては、従来から、セルロース製透析膜が利用されてきた。しかしながら、この血液透析法だけで、多様な患者の病態を健常者に近づけるには限界がある。すなわち、血液透析法によって患者から除去可能な物質はセルロース膜を透過する溶質のみであるため、分子量の比較的大きな溶質の除去は血液透析では対処することができない。
このような背景をもとに、血液中から毒性物質を直接除去することのできる手法として、血液透析に代わる手法が求められ、直接血液灌流（ＤｉｒｅｃｔＨｅｍｏｐｅｒｆｕｓｉｏｎ，ＤＨＰ）が開発された。この直接血液灌流法とは、活性炭などの吸着剤を血液に直接に接触させて、毒性物質を吸着除去する手法であり、吸着型血液浄化器などが厚生労働省から既に承認されており、臨床的にも普及している。
【０００３】
前記の直接血液灌流法において用いる吸着剤は、血液と直接に接触し、しかも吸着処理後の血液を体内に戻すことになるので、吸着能以外にも種々の物性が要求される。すなわち、血液は、一般的に異物に接触すると凝血するので、血液を吸着剤（例えば、活性炭）と直接に接触させて毒性物質や不要な溶質を吸着させるためには、吸着剤表面を抗血栓性に改善する必要がある。また、血球の破壊防止と吸着剤粉末による血管閉塞の防止も必要である。
そこで、例えば、特公昭５５−４９８６８号公報（特許文献１）や特公昭５８−４１０６６号公報（特許文献２）などに記載されているように、活性炭などの吸着剤表面に樹脂皮膜を形成する技術が知られている。また、樹脂などで被覆処理する前の活性炭それ自体を改良することによって、より優れた吸着剤を提供することが可能になるはずである。例えば、特公昭６０−２２９４７号公報（特許文献３）や特公平１−２７９７１号公報（特許文献４）などには、熱硬化性樹脂を主原料として製造された粒状活性炭が記載されている。
【０００４】
【特許文献１】
特公昭５５−４９８６８号公報
【特許文献２】
特公昭５８−４１０６６号公報
【特許文献３】
特公昭６０−２２９４７号公報
【特許文献４】
特公平１−２７９７１号公報
【０００５】
【発明が解決しようとする課題】
本発明者は、直接血液灌流法において用いる吸着剤の原料となる活性炭それ自体の物性を向上させる研究を鋭意行ったところ、従来品（人工臓器用吸着剤ＭＵ−ＡＺ：呉羽化学工業）において達成されていた種々の物性を損なうことなく、分子量が比較的大きい物質の吸着能が向上し、しかも水中振盪摩耗率も向上した新規の球状活性炭の開発に成功した。
すなわち、本発明者が開発した新規の球状活性炭では、分子量約１００〜１０００の毒性物質に対する吸着能は、従来の球状活性炭と少なくとも同程度であるが、分子量約１０００〜１００００（ビタミンＢ₁₂と同程度の分子量）の毒性物質に対する吸着能が、従来の球状活性炭よりも向上する。また、本発明者が開発した新規の球状活性炭では、従来の球状活性炭と比較して水中振盪摩耗率も向上するので、吸着剤粉末の発生が一層抑制され、吸着剤粉末による血管閉塞の防止効果が向上する。
本発明は、こうした知見に基づくものである。
【０００６】
【課題を解決するための手段】
従って、本発明は、直径が０．１〜１ｍｍであり、Ｈ／Ｃが０．１４以下であり、そして細孔直径５〜１０００ｎｍの細孔容積が０．２５〜０．５５ｍＬ／ｇであることを特徴とする、血液の直接灌流用球状活性炭に関する。
また、本発明は、多孔性球状酸化ピッチ又は球状活性炭前駆体を不活性ガス雰囲気中で１０００〜２５００℃で熱処理を行い、続いて、水蒸気と酸素と不活性ガスの混合ガス雰囲気中で７５０〜１２００℃で賦活処理を行うことを特徴とする、前記の血液直接灌流用球状活性炭の製造方法にも関する。
【０００７】
【発明の実施の形態】
本発明による球状活性炭は、直径が０．１〜１ｍｍである。球状活性炭の直径が０．１ｍｍ未満になると、球状活性炭の外表面積が増加し、有益物質の吸着が起こりやすくなるとともに、血液浄化時の活性炭充填層の圧力損失が大きくなり、血球が破壊するおそれがあるので好ましくない。また、直径が１ｍｍを超えると、球状活性炭内部への毒性物質の拡散距離が増加し、吸着速度が低下するので好ましくない。直径は、好ましくは０．３〜１ｍｍである。なお、本明細書で「直径がＤｌ〜Ｄｕである」という表現は、ＪＩＳＫ１４７４に準じて作成した粒度累積線図（平均粒子径の測定方法に関連して後で説明する）において、ふるいの目開きＤｌ〜Ｄｕの範囲に対応するふるい通過百分率（％）が９０％以上であることを意味する。
【０００８】
本発明による球状活性炭は、元素分析により求めた水素原子と炭素原子との比率（Ｈ／Ｃ：以下「Ｈ／Ｃ」と略記することがある）が０．１４以下である。Ｈ／Ｃが０．１４を越えると、毒性物質に対する吸着能が、従来公知の球状活性炭と同程度まで低下するか、あるいはそれ以下に低下するので、好ましくない。Ｈ／Ｃの好ましい範囲は、例えば０．１３以下である。吸着能の観点からはＨ／Ｃの下限は特に限定されないが、Ｈ／Ｃ値を低下させるためには焼成処理温度を高くする必要があるので、経済性の観点から０．０５以上であることが好ましい。
【０００９】
本発明による球状活性炭は、細孔直径５〜１０００ｎｍの細孔容積が０．２５〜０．５５ｍＬ／ｇである。この細孔容積が０．２５ｍＬ／ｇ未満になると毒性物質に対する吸着能が低下するので好ましくない。また、この細孔容積が０．５５ｍＬ／ｇを超えると表面強度が低下し、水中振盪摩耗率が大きくなるので好ましくない。前記の細孔容積は、好ましくは０．２８〜０．５２ｍＬ／ｇであり、特に好ましくは０．３〜０．５２ｍＬ／ｇである。なお、細孔直径５〜１０００ｎｍの細孔容積の測定方法は後述する。
【００１０】
本発明による球状活性炭の好ましい態様においては、ＢＥＴ法により求められる比表面積（以下「ＳＳＡ」と省略することがある）が８００ｍ²／ｇ以上である。ＳＳＡが８００ｍ²／ｇより小さい球状活性炭では、毒性物質に対する吸着能が低くなるので好ましくない。ＳＳＡは、より好ましくは１０００ｍ²／ｇ以上である。ＳＳＡの上限は特に限定されるものではないが、カサ密度及び強度の観点から、ＳＳＡは２５００ｍ²／ｇ以下であることが好ましい。
【００１１】
本発明による球状活性炭の好ましい態様においては、水中振盪摩耗率が０．０８％以下である。水中振盪摩耗率の測定方法は後述する。
また、本発明による球状活性炭の好ましい態様においては、カサ密度が０．４０〜０．５５ｇ／ｍＬであり、より好ましくは０．４０〜０．５０ｇ／ｍＬである。カサ密度が０．４０〜０．５５ｇ／ｍＬの範囲になると、単位体積あたりの吸着能が大きい点で好ましい。カサ密度の測定方法は後述する。
更に、本発明による球状活性炭の好ましい態様においては、ビタミンＢ₁₂の吸着率が９３％以上である。ビタミンＢ₁₂の吸着率の測定方法は後述する。
【００１２】
本発明の球状活性炭は、例えば、以下の方法によって製造することができる。最初に、石油ピッチ又は石炭ピッチ等の等方性ピッチに対し、添加剤として、沸点２００℃以上の２環式又は３環式の芳香族化合物又はその混合物を加えて加熱混合した後、成形してピッチ成形体を得る。なお、本発明による前記球状活性炭は、血液の直接灌流用吸着剤として利用するので、その原料も、安全上充分な純度を有し、且つ品質的に安定であることが必要である。
【００１３】
次に、７０〜１８０℃の熱水中で、前記のピッチ成形体を攪拌下に分散造粒し、冷却して微小球体化する。更に、ピッチに対して低溶解度を有し、かつ前記添加剤に対して高溶解度を有する溶剤で、微小球体化ピッチ成形体から添加剤を抽出除去し、得られた多孔性球状ピッチを、酸化剤を用いて酸化すると、熱に対して不融性の多孔性球状酸化ピッチが得られる。この不融化処理は、例えば、空気中にて、２００〜３００℃にて加熱することによって実施することができる。
【００１４】
こうして得られた不融性の多孔性球状酸化ピッチを、不活性ガス（例えば、窒素、アルゴン、若しくはヘリウム、あるいはそれらの混合物）中で、１０００〜２５００℃（好ましくは１０５０〜１５００℃）の温度で焼成処理し、更に、水蒸気、酸素及び不活性ガス（例えば、窒素、アルゴン、若しくはヘリウム、あるいはそれらの混合物）の存在下で、７５０〜１２００℃、好ましくは８００〜１０００℃にてカサ密度が０．４０〜０．５５ｇ／ｍＬに達するまで賦活処理すると、本発明による球状活性炭を得ることができる。
前記の賦活処理における雰囲気中の水蒸気の濃度は４０〜７０ｖｏｌ％が好ましく、酸素の濃度は０．１〜１ｖｏｌ％が好ましい。
【００１５】
熱処理後の賦活処理時間を短縮するため、予め多孔性球状酸化ピッチを、水蒸気が主成分であるガス雰囲気中で７５０〜１０００℃で、カサ密度が０．６ｇ／ｍＬ以上になるまで賦活処理（予備賦活処理）して得られた球状活性炭前駆体を熱処理前の原料として用いることもできる。ここで、水蒸気が主成分であるガス雰囲気としては、例えば、水蒸気４０〜７０ｖｏｌ％を含む不活性ガス（例えば、窒素、アルゴン、若しくはヘリウム、あるいはそれらの混合物）を用いることができる。
【００１６】
前記の原料ピッチに対して、芳香族化合物を添加する目的は、原料ピッチの流動性を向上させ微小球体化を容易にすること及び成形後のピッチ成形体からその添加剤を抽出除去させることにより成形体を多孔質とし、その後の工程による構造制御ならびに焼成を容易にすることにある。このような添加剤としては、例えば、ナフタレン、メチルナフタレン、フェニルナフタレン、ベンジルナフタレン、メチルアントラセン、フェナンスレン、又はビフェニル等を単独で、又はそれらの２種以上の混合物を用いることができる。ピッチに対する添加量は、ピッチ１００重量部に対し芳香族化合物１０〜５０重量部の範囲が好ましい。
【００１７】
ピッチと添加剤との混合は、均一な混合を達成するために、加熱して溶融状態で行うのが好ましい。ピッチと添加剤との混合物は、得られる球状活性炭の粒径（直径）を制御するため、粒径約０．１〜１ｍｍの粒子に成形することが好ましい。成形は溶融状態で行ってもよく、また混合物を冷却後に粉砕する等の方法によってもよい。
【００１８】
ピッチと添加剤との混合物から添加剤を抽出除去するための溶剤としては、例えば、ブタン、ペンタン、ヘキサン、又はヘプタン等の脂肪族炭化水素、ナフサ、又はケロシン等の脂肪族炭化水素を主成分とする混合物、あるいはメタノール、エタノール、プロパノール、又はブタノール等の脂肪族アルコール類等が好適である。
このような溶剤でピッチと添加剤との混合物成形体から添加剤を抽出することによって、成形体の形状を維持したまま、添加剤を成形体から除去することができる。この際に、成形体中に添加剤の抜け穴が形成され、均一な多孔性を有するピッチ成形体が得られるものと推定される。
【００１９】
前記の製造方法によって得られた本発明の球状活性炭の表面を、例えば、前記特公昭５５−４９８６８号公報又は特公昭５８−４１０６６号公報に記載の方法によって被覆することによって、直接灌流用吸着剤を得ることができる。具体的には、例えば、本発明による球状活性炭を、疎水性高分子物質によって下地被覆処理して下地被覆層を形成し、続いて、親水性高分子物質によって上地被覆処理して上地被覆層を形成し、更に必要により、上地被覆層を架橋処理することによって、直接灌流用吸着剤を得ることができる。
【００２０】
本発明による球状活性炭は、前記のとおり、その表面を被覆処理して血液試料の直接灌流用吸着剤として用いることができる。しかしながら、本発明による球状活性炭をそのまま、あるいは適当に後加工してから、一般的な活性炭と同様に、例えば、水処理、空気浄化、脱臭、工業薬品の精製、食品精製、食品脱色、溶剤回収、触媒、貴金属回収、あるいはダイオキシン類などの有害物質の回収にも利用することができる。
【００２１】
前記の血液試料直接灌流用吸着剤は、前記のとおり、例えば、直接血液灌流（ＤｉｒｅｃｔＨｅｍｏｐｅｒｆｕｓｉｏｎ，ＤＨＰ）に用いることができる。ここで「血液試料」とは、血液（全血）だけでなく、血漿なども含む。従って、前記の血液試料直接灌流用吸着剤は、血液（全血）の体外処理だけでなく、血漿の体外処理にも用いることができる。
【００２２】
本発明による球状活性炭が有する各物性値、すなわち、直径（平均粒子径）、細孔容積、カサ密度、比表面積、水中振盪摩耗率、及びビタミンＢ₁₂吸着率は、以下の方法によって測定する。
（１）平均粒子径
球状活性炭についてＪＩＳＫ１４７４に準じて粒度累積線図を作成する。平均粒子径は、粒度累積線図において、横軸の５０％の点の垂直線と粒度累積線との交点から、横軸に水平線を引いて交点の示すふるいの目開き（ｍｍ）を求めて、平均粒子径とする。
【００２３】
（２）水銀圧入法による細孔容積
水銀ポロシメーター（例えば、ＭＩＣＲＯＭＥＲＩＴＩＣＳ社製「ＡＵＴＯＰＯＲＥ９２００」）を用いて細孔容積を測定することができる。試料である球状活性炭を試料容器に入れ、２．６７Ｐａ以下の圧力で３０分間脱気する。次いで、水銀を試料容器内に導入し、徐々に加圧して水銀を球状活性炭試料の細孔へ圧入する（最高圧力＝４１４ＭＰａ）。このときの圧力と水銀の圧入量との関係から以下の各計算式を用いて球状活性炭試料の細孔容積分布を測定する。
具体的には、細孔直径１５μｍに相当する圧力（０．０７ＭＰａ）から最高圧力（４１４ＭＰａ：細孔直径３ｎｍ相当）までに球状活性炭試料に圧入された水銀の体積を測定する。細孔直径の算出は、直径（Ｄ）の円筒形の細孔に水銀を圧力（Ｐ）で圧入する場合、水銀の表面張力を「γ」とし、水銀と細孔壁との接触角を「θ」とすると、表面張力と細孔断面に働く圧力の釣り合いから、次式：
−πＤγｃｏｓθ＝π（Ｄ／２）²・Ｐ
が成り立つ。従って
Ｄ＝（−４γｃｏｓθ）／Ｐ
となる。
本明細書においては、水銀の表面張力を４８４ｄｙｎｅ／ｃｍとし、水銀と炭素との接触角を１３０度とし、圧力ＰをＭＰａとし、そして細孔直径Ｄをμｍで表示し、下記式：
Ｄ＝１．２７／Ｐ
により圧力Ｐと細孔直径Ｄの関係を求める。本明細書において細孔直径５〜１０００ｎｍの範囲の細孔容積とは、水銀圧入圧１．２７〜２５４ＭＰａまでに圧入された水銀の体積に相当する。
【００２４】
（３）カサ密度
試料である球状活性炭を、１１５℃に調節した乾燥器中で３時間乾燥した後、デシケーター中で放冷する。乾燥した球状活性炭試料を、充填密度測定容器（ＪＩＳＫ１４７４−５．７の図８に示された容器）に、その容器の容積の約１／５容量まで入れる。前記球状活性炭試料の上面が一定の高さになるまで、ゴム板上で静かにたたき、更に同量の球状活性炭試料を加えて静かにたたく。このたたき充填操作を繰り返し、容器の上端まで球状活性炭試料を充填し、容器上部の筒を抜き取り、ステンレスステール製直定規を用いて盛り上がった部分を削り取り、球状活性炭試料の上面を水平にする。前記容器内の球状活性炭試料の質量を０．１ｇの桁まで測定する。続いて、充填密度（Ｌ）は次の式によって算出する。
Ｌ＝Ｓ／Ｍ
前記の式で、Ｌはカサ密度（ｇ／ｍＬ）であり、Ｓは球状活性炭試料の質量（ｇ）であり、Ｍは充填密度測定容器の容積（ｍＬ）である。
【００２５】
（４）比表面積
連続流通式のガス吸着法による比表面積測定器（例えば、ＭＩＣＲＯＭＥＲＩＴＩＣＳ社製「ＦｌｏｗＳｏｒｂＩＩ２３００」）を用いて、球状活性炭試料のガス吸着量を測定し、ＢＥＴの式により比表面積を計算することができる。具体的には、試料である球状活性炭を試料管に充填し、その試料管に窒素３０ｖｏｌ％を含有するヘリウムガスを流しながら以下の操作を行い、球状活性炭試料への窒素吸着量を求める。すなわち、試料管を−１９６℃に冷却し、球状活性炭試料に窒素を吸着させる。次に、試料管を室温に戻す。このとき球状活性炭試料から脱離してくる窒素量を熱伝導型検出器で測定し、吸着ガス量（ｖ）とする。
ＢＥＴの式から誘導された近似式：
ｖ_m＝１／（ｖ・（１−ｘ））
を用いて液体窒素温度における、窒素吸着による１点法（相対圧力ｘ＝０．３）によりｖ_mを求め、次式：
比表面積＝４．３５×ｖ_m＝（ｍ²／ｇ）
により試料の比表面積を計算する。前記の各計算式で、ｖ_mは試料表面に単分子量を形成するのに必要な吸着量（ｃｍ³／ｇ）であり、ｖは実測される吸着量（ｃｍ³／ｇ）であり、ｘは相対圧力である。
【００２６】
（５）水中振盪摩耗率
濾過装置にメンブランフィルターを取り付け、メンブランフィルターに含まれる水を吸引濾過する。メンブランフィルターを取り外し、そのメンブランフィルターを１１５℃に調節された乾燥器で３０分間乾燥する。デシケーターで３０分間放冷した後、メンブランフィルターの質量を０．１ｍｇの桁まで測定する。
一方、試料である球状活性炭（約５０ｍＬ）を、１１５℃に調節した恒温乾燥器中で３時間乾燥した後、デシケーター中で放冷する。乾燥した球状活性炭試料約１０ｇを０．１ｍｇの桁まで測定し、その測定値を球状活性炭試料質量（Ｓ）とする。続いて、球状活性炭試料を振盪用瓶に移し、水５０ｍＬを加えた後、振盪数２４５±５ｒ／ｍｉｎで３０分間振盪する。ふるいで濾過し、大きな粒状の球状活性炭試料を取り除いた試料液を、質量を測定した前記メンブランフィルターが取り付けられた濾過装置で吸引濾過する。粉状の濾過残分が付着しているメンブランフィルターの質量を測定し、瓶に移し、１１５℃に調節された乾燥器で３０分間乾燥する。デシケーターで３０分間放冷した後、粉状の濾過残分が付着しているメンブランフィルターの乾燥質量を０．１ｍｇの桁まで測定し、粉状濾過残分量（Ｒ）を求める。水中振盪摩耗率（Ａ）は、次の式によって算出する。
Ａ＝（Ｒ／Ｓ）×１００
前記の式で、Ａは水中振盪摩耗率（％）であり、Ｒは濾過残分の質量（ｇ）であり、そしてＳは球状活性炭試料の質量（ｇ）である。
【００２７】
（６）ビタミンＢ₁₂の吸着除去能
球状活性炭試料約５ｇを、１１５℃に調節された恒温乾燥機中で３時間乾燥させた後、デシケーター中で放冷する。吸着試験用ビーカーに、予めビタミンＢ₁₂原液濃度（Ｆ）がわかっているビタミンＢ₁₂標準原液を正確に１００ｍＬの量で入れる。そして、３７℃に調節された水浴中に浸す。ビタミンＢ₁₂標準原液の液温が３７℃になったら、乾燥した球状活性炭試料を１±０．００１ｇの範囲で０．１ｍｇの桁まで秤量して取り、ビーカーに入れ、回転数４０５ｒ／ｍｉｎで３０分間攪拌し、濾過する。得られた濾液及び標準原液に関して、分光光度計を用いて波長５２０ｎｍにおける吸光度を測定する。標準原液の吸光度より検量線を作成し、濾液の吸光度よりビタミンＢ₁₂残存濃度（Ｅ）を求める。ビタミンＢ₁₂吸着除去率（Ｄ）は、次の式によって算出する。
Ｄ（％）＝〔（１０−Ｅ）／Ｆ〕×１００
前記の式で、ＤはビタミンＢ₁₂吸着除去率（％）であり、ＥはビタミンＢ₁₂残存濃度（ｍｇ／１００ｍＬ）であり、そしてＦはビタミンＢ₁₂原液濃度（ｍｇ／１００ｍＬ）である。
【００２８】
【実施例】
以下、実施例によって本発明を具体的に説明するが、これらは本発明の範囲を限定するものではない。
【００２９】
【実施例１】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）６８ｋｇと、ナフタレン３２ｋｇとを、攪拌翼のついた内容積３００Ｌの耐圧容器に仕込み、１８０℃で溶融混合を行った後、８０〜９０℃に冷却して押し出し、紐状成形体を得た。次いで、この紐状成形体を直径と長さの比が約１〜２になるように破砕した。この破砕物に、０．２３重量％のポリビニルアルコール（ケン化度＝８８％）水溶液１２０ｋｇを加え、９５℃で３５０ｒｐｍの速度で攪拌して分散させた後、急冷して分散粒子を凝固させ、球状ピッチ成形体を得た。
更に、濾過を行って水分を除去し、球状ピッチ成形体の約６倍重量のｎ−ヘキサンで球状ピッチ成形体中のナフタレンを抽出除去した。続いて、空気中にて、２６０℃で１時間保持して酸化処理を行い、不融性多孔性球状酸化ピッチを得た。
次に、不融性多孔性球状酸化ピッチに対して、窒素ガス雰囲気中で１３５０℃で４時間の焼成処理を行った。更に、５０ｖｏｌ％の水蒸気と０．５ｖｏｌ％の酸素とを含む窒素ガス雰囲気中で、８２０℃で１２時間の賦活処理を実施し、本発明による球状活性炭を得た。
【００３０】
【実施例２】
賦活処理を９００℃で５時間実施したこと以外は、実施例１に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３１】
【実施例３】
焼成処理を２０００℃で実施し、賦活処理を９００℃で１０時間実施したこと以外は、実施例１に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３２】
【実施例４】
焼成処理を１１００℃で実施し、賦活処理を９００℃で４時間実施したこと以外は、実施例１に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３３】
【実施例５】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）６８ｋｇと、ナフタレン３２ｋｇとを、攪拌翼のついた内容積３００Ｌの耐圧容器に仕込み、１８０℃で溶融混合を行った後、８０〜９０℃に冷却して押し出し、紐状成形体を得た。次いで、この紐状成形体を直径と長さの比が約１〜２になるように破砕した。この破砕物に、０．２３重量％のポリビニルアルコール（ケン化度＝８８％）水溶液１２０ｋｇを加え、９５℃で３５０ｒｐｍの速度で攪拌して分散させた後、急冷して分散粒子を凝固させ、球状ピッチ成形体を得た。
更に、濾過を行って水分を除去し、球状ピッチ成形体の約６倍重量のｎ−ヘキサンで球状ピッチ成形体中のナフタレンを抽出除去した。続いて、空気中にて、２６０℃で１時間保持して酸化処理を行い、不融性多孔性球状酸化ピッチを得た。
次に、得られた不融性多孔性球状酸化ピッチを、水蒸気５０ｖｏｌ％を含む窒素ガス中で、カサ密度が０．６ｇ／ｍＬ以上になるまで、予備賦活処理を実施して球状活性炭前駆体を得た。カサ密度が０．６ｇ／ｍＬ以上になることは、予備賦活処理中に球状活性炭前駆体の一部を予備賦活炉より取り出して、カサ密度を測定することによって確認することができる。
次に、球状活性炭前駆体を、窒素ガス雰囲気中で１３５０℃で４時間の焼成処理を行った。更に、５０ｖｏｌ％の水蒸気と０．５ｖｏｌ％の酸素とを含む窒素ガス雰囲気中で９００℃で４時間の賦活処理を実施し、本発明による球状活性炭を得た。
【００３４】
【実施例６】
賦活処理時間を７時間としたこと以外は、実施例５に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３５】
【実施例７】
熱処理温度を２０００℃とし、賦活処理時間を１０時間としたこと以外は、実施例５に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３６】
【実施例８】
熱処理温度を１１００℃とし、賦活処理時間を７時間としたこと以外は、実施例５に記載の操作を繰り返して、本発明による球状活性炭を得た。
【００３７】
【比較例１】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）６８ｋｇと、ナフタレン３２ｋｇとを、攪拌翼のついた内容積３００Ｌの耐圧容器に仕込み、１８０℃で溶融混合を行った後、８０〜９０℃に冷却して押し出し、紐状成形体を得た。次いで、この紐状成形体を直径と長さの比が約１〜２になるように破砕した。この破砕物に、０．２３重量％のポリビニルアルコール（ケン化度＝８８％）水溶液１２０ｋｇを加え、９５℃で３５０ｒｐｍの速度で攪拌して分散させた後、急冷して分散粒子を凝固させ、球状ピッチ成形体を得た。
更に、濾過を行って水分を除去し、球状ピッチ成形体の約６倍重量のｎ−ヘキサンで球状ピッチ成形体中のナフタレンを抽出除去した。続いて、空気中にて、２６０℃で１時間保持して酸化処理を行い、不融性多孔性球状酸化ピッチを得た。
次に、不融性多孔性球状酸化ピッチに対して、窒素ガス雰囲気中で８２０℃で０．５時間の焼成処理を行った。更に、５０ｖｏｌ％の水蒸気と０．５ｖｏｌ％の酸素とを含む窒素ガス雰囲気中で、８２０℃で２時間の賦活処理を実施し、比較用の球状活性炭を得た。
【００３８】
【比較例２】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）６８ｋｇと、ナフタレン３２ｋｇとを、攪拌翼のついた内容積３００Ｌの耐圧容器に仕込み、１８０℃で溶融混合を行った後、８０〜９０℃に冷却して押し出し、紐状成形体を得た。次いで、この紐状成形体を直径と長さの比が約１〜２になるように破砕した。この破砕物に、０．２３重量％のポリビニルアルコール（ケン化度＝８８％）水溶液１２０ｋｇを加え、９５℃で３５０ｒｐｍの速度で攪拌して分散させた後、急冷して分散粒子を凝固させ、球状ピッチ成形体を得た。
更に、濾過を行って水分を除去し、球状ピッチ成形体の約６倍重量のｎ−ヘキサンで球状ピッチ成形体中のナフタレンを抽出除去した。続いて、空気中にて、２６０℃で１時間保持して酸化処理を行い、不融性多孔性球状酸化ピッチを得た。
次に、得られた不融性多孔性球状酸化ピッチを、水蒸気５０ｖｏｌ％を含む窒素ガス中で、カサ密度が０．６ｇ／ｍＬ以上になるまで、予備賦活処理を実施して球状活性炭前駆体を得た。カサ密度が０．６ｇ／ｍＬ以上になることは、予備賦活処理中に球状活性炭前駆体の一部を予備賦活炉より取り出して、カサ密度を測定することによって確認することができる。
次に、球状活性炭前駆体に対して、窒素ガス雰囲気中で１３５０℃で４時間の焼成処理を行った。更に、５０ｖｏｌ％の水蒸気を含み、酸素を全く含まない窒素ガス雰囲気中で、９００℃で６時間の賦活処理を実施し、比較用の球状活性炭を得た。
【００３９】
【比較例３】
５０ｖｏｌ％の水蒸気を含み、０．５ｖｏｌ％の酸素を含む窒素ガス雰囲気中で１時間の賦活処理を実施したこと以外は、比較例２に記載の操作を繰り返して、比較用の球状活性炭を得た。
【００４０】
【比較例４】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）及びナフタレンにコバルト０．０１重量％を添加したこと、賦活処理時間を１時間としたこと以外は、比較例１に記載の操作を繰り返して、比較用の球状活性炭を得た。
【００４１】
【比較例５】
石油系ピッチ（軟化点＝２１０℃，キノリン不溶分＝１重量％以下，Ｈ／Ｃ原子比＝０．６３）に代えて、別の石油系ピッチ（軟化点＝１９２℃，キノリン不溶分＝３４．２重量％以下，Ｈ／Ｃ原子比＝０．５３）を用いたこと以外は、比較例１に記載の操作を繰り返して、比較用の球状活性炭を得た。
【００４２】
なお、上記実施例１〜８及び比較例１〜５に記載の各製造条件を、以下の表１にまとめて示した。
【００４３】
【表１】

【００４４】
【物性評価】
前記の実施例１〜８及び比較例１〜５に記載の製造条件に基づいて得られた球状活性炭について、その直径（平均粒子径）、細孔容積、カサ密度、比表面積、Ｈ／Ｃ、水中振盪摩耗率、及びビタミンＢ₁₂吸着率を測定した。各物性値は、前記の測定方法によって測定した。得られた各物性値を表２にまとめて示す。
【００４５】
【表２】

【００４６】
実施例１〜８で得られた本発明の球状活性炭は、いずれも、水中振盪摩耗率が血液の直接灌流用球状活性炭として充分使用できる値であり、ビタミンＢ₁₂の吸着除去能も高い値を示した。
一方、比較例１〜３で得られた比較用球状活性炭においては、水中振盪摩耗率が血液の直接灌流用球状活性炭として充分使用できる値ではあったが、ビタミンＢ₁₂の吸着除去能が充分ではなかった。また、比較例４で得られた比較用球状活性炭においては、ビタミンＢ₁₂の吸着除去能は充分な値を示したが、水中振盪摩耗率が大きく、血液の直接灌流用球状活性炭としては適さない。更に、比較例５で得られた比較用球状活性炭は、水中振盪摩耗率及びビタミンＢ₁₂の吸着除去能がいずれも不充分である。
【００４７】
【発明の効果】
本発明による新規の球状活性炭によれば、直接血液灌流法において用いる吸着剤の原料となる従来公知の活性炭において達成されていた種々の物性を損なうことなく、分子量が比較的大きい物質の吸着能が向上し、しかも水中振盪摩耗率も向上する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spherical activated carbon for direct perfusion of blood and a method for producing the same.
[0002]
[Prior art]
For the purpose of removing toxic substances contained in the blood of patients with kidney disease, etc., a blood circulation path is formed outside the patient's body, the patient's blood is taken out of the body, and purification is performed outside the body. There is a treatment method that returns blood to the patient again. As a representative means for such blood purification, a dialysis membrane made of cellulose has been conventionally used. However, there is a limit in bringing various patient pathologies closer to healthy individuals by this hemodialysis method alone. That is, since the only substance that can be removed from a patient by hemodialysis is a solute that permeates the cellulose membrane, removal of a solute having a relatively large molecular weight cannot be dealt with by hemodialysis.
Based on this background, an alternative to hemodialysis has been sought as a technique that can directly remove toxic substances from the blood, and direct blood perfusion (DHP) has been developed. This direct blood perfusion method is a method of adsorbing and removing toxic substances by directly adsorbing an adsorbent such as activated carbon to the blood. Adsorption-type blood purifiers have already been approved by the Ministry of Health, Labor and Welfare and are clinically It is also popular.
[0003]
Since the adsorbent used in the direct blood perfusion method is in direct contact with blood and returns the blood after adsorption treatment to the body, various physical properties are required in addition to the adsorption ability. That is, blood generally clots when it comes into contact with a foreign substance. Therefore, in order to adsorb toxic substances and unnecessary solutes by directly contacting blood with an adsorbent (for example, activated carbon), the surface of the adsorbent is antithrombotic. It is necessary to improve to sex. It is also necessary to prevent blood cell destruction and blood vessel occlusion with adsorbent powder.
Therefore, for example, as described in Japanese Patent Publication No. 55-49868 (Patent Document 1) and Japanese Patent Publication No. 58-41066 (Patent Document 2), a resin film is formed on the surface of an adsorbent such as activated carbon. Technology is known. Also, it should be possible to provide a better adsorbent by improving the activated carbon itself before being coated with a resin or the like. For example, Japanese Patent Publication No. 60-22947 (Patent Document 3) and Japanese Patent Publication No. 1-227971 (Patent Document 4) describe granular activated carbon produced using a thermosetting resin as a main raw material.
[0004]
[Patent Document 1]
Japanese Patent Publication No.55-49868
[Patent Document 2]
Japanese Patent Publication No. 58-41066
[Patent Document 3]
Japanese Patent Publication No. 60-22947
[Patent Document 4]
Japanese Patent Publication No. 1-227971
[0005]
[Problems to be solved by the invention]
The present inventor has intensively studied to improve the physical properties of the activated carbon itself that is the raw material of the adsorbent used in the direct blood perfusion method, and achieved it in the conventional product (artificial organ adsorbent MU-AZ: Kureha Chemical Industry). The present inventors succeeded in developing a new spherical activated carbon with improved adsorption ability for substances having a relatively large molecular weight and improved underwater shaking wear rate without impairing various physical properties.
That is, in the novel spherical activated carbon developed by the present inventors, the adsorption capacity for toxic substances having a molecular weight of about 100 to 1000 is at least the same as that of conventional spherical activated carbon, but the molecular weight is about 1000 to 10,000 (vitamin B). ₁₂ The adsorbability for toxic substances having the same molecular weight as that of the conventional spherical activated carbon is improved. In addition, the new spherical activated carbon developed by the present inventor also improves the underwater shaking wear rate compared to conventional spherical activated carbon, so that the generation of adsorbent powder is further suppressed, and the blood vessel occlusion prevention effect by the adsorbent powder. Will improve.
The present invention is based on these findings.
[0006]
[Means for Solving the Problems]
Therefore, the present invention has a diameter of 0.1 to 1 mm, H / C of 0.14 or less, and a pore volume having a pore diameter of 5 to 1000 nm is 0.25 to 0.55 mL / g. The present invention relates to a spherical activated carbon for direct perfusion of blood.
In the present invention, the porous spherical oxide pitch or the spherical activated carbon precursor is heat-treated at 1000 to 2500 ° C. in an inert gas atmosphere, and subsequently, 750 to 750 in a mixed gas atmosphere of water vapor, oxygen, and inert gas. The present invention also relates to a method for producing the spherical activated carbon for direct blood perfusion, wherein the activation treatment is performed at 1200 ° C.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The spherical activated carbon according to the present invention has a diameter of 0.1 to 1 mm. When the diameter of the spherical activated carbon is less than 0.1 mm, the outer surface area of the spherical activated carbon increases, the adsorption of beneficial substances is likely to occur, and the pressure loss of the activated carbon packed bed during blood purification increases, and the blood cells may be destroyed. This is not preferable. On the other hand, if the diameter exceeds 1 mm, the diffusion distance of the toxic substance into the spherical activated carbon increases, and the adsorption rate decreases, which is not preferable. The diameter is preferably 0.3 to 1 mm. In the present specification, the expression “diameter is D1 to Du” is a sieve in a particle size cumulative diagram prepared in accordance with JIS K 1474 (which will be described later in connection with the method of measuring the average particle size). It means that the sieve passing percentage (%) corresponding to the range of the mesh openings Dl to Du is 90% or more.
[0008]
The spherical activated carbon according to the present invention has a ratio of hydrogen atoms to carbon atoms (H / C: hereinafter sometimes abbreviated as “H / C”) determined by elemental analysis of 0.14 or less. If H / C exceeds 0.14, the adsorptive capacity for toxic substances is reduced to the same level as that of conventionally known spherical activated carbon, or lower than that. A preferable range of H / C is, for example, 0.13 or less. From the standpoint of adsorption capacity, the lower limit of H / C is not particularly limited, but in order to reduce the H / C value, it is necessary to increase the firing temperature, so that it is 0.05 or more from the viewpoint of economy. Is preferred.
[0009]
The spherical activated carbon according to the present invention has a pore volume of 5 to 1000 nm and a pore volume of 0.25 to 0.55 mL / g. When the pore volume is less than 0.25 mL / g, the adsorptive capacity for toxic substances decreases, which is not preferable. On the other hand, when the pore volume exceeds 0.55 mL / g, the surface strength is lowered and the rate of underwater shaking wear is increased, which is not preferable. The pore volume is preferably 0.28 to 0.52 mL / g, and particularly preferably 0.3 to 0.52 mL / g. A method for measuring the pore volume having a pore diameter of 5 to 1000 nm will be described later.
[0010]
In a preferred embodiment of the spherical activated carbon according to the present invention, the specific surface area (hereinafter sometimes abbreviated as “SSA”) determined by the BET method is 800 m. ² / G or more. SSA is 800m ² A spherical activated carbon smaller than / g is not preferable because the adsorptive capacity for toxic substances is lowered. SSA is more preferably 1000 m ² / G or more. The upper limit of SSA is not particularly limited, but from the viewpoint of bulk density and strength, SSA is 2500 m. ² / G or less is preferable.
[0011]
In a preferred embodiment of the spherical activated carbon according to the present invention, the underwater shaking wear rate is 0.08% or less. Measuring method of underwater shaking wear rate Is It will be described later.
Moreover, in the preferable aspect of the spherical activated carbon by this invention, the bulk density is 0.40-0.55 g / mL, More preferably, it is 0.40-0.50 g / mL. When the bulk density is in the range of 0.40 to 0.55 g / mL, it is preferable in that the adsorption capacity per unit volume is large. Measuring method of density Is It will be described later.
Furthermore, in a preferred embodiment of the spherical activated carbon according to the present invention, vitamin B ₁₂ Is an adsorption rate of 93% or more. Vitamin B ₁₂ Method for measuring adsorption rate Is It will be described later.
[0012]
The spherical activated carbon of the present invention can be produced, for example, by the following method. First, a bicyclic or tricyclic aromatic compound having a boiling point of 200 ° C. or higher is added as an additive to an isotropic pitch such as petroleum pitch or coal pitch, and the mixture is heated and mixed, and then molded. To obtain a pitch compact. Since the spherical activated carbon according to the present invention is used as an adsorbent for direct perfusion of blood, it is necessary that the raw material has sufficient purity for safety and is stable in quality.
[0013]
Next, the above pitch compact is dispersed and granulated with stirring in hot water at 70 to 180 ° C., and cooled to form microspheres. Further, the additive is extracted and removed from the microspherical pitch molded body with a solvent having low solubility for pitch and high solubility for the additive, and the resulting porous spherical pitch is oxidized. When oxidized with an agent, a porous spherical oxidized pitch that is infusible to heat is obtained. This infusibilization treatment can be performed, for example, by heating at 200 to 300 ° C. in the air.
[0014]
The infusible porous spherical oxide pitch thus obtained is heated to 1000 to 2500 ° C. (preferably 1050 to 1500 ° C.) in an inert gas (for example, nitrogen, argon, or helium, or a mixture thereof). And a bulk density at 750 to 1200 ° C., preferably 800 to 1000 ° C. in the presence of water vapor, oxygen and an inert gas (for example, nitrogen, argon, or helium, or a mixture thereof). When the activation treatment is performed until 0.40 to 0.55 g / mL is reached, the spherical activated carbon according to the present invention can be obtained.
The concentration of water vapor in the atmosphere in the activation treatment is preferably 40 to 70 vol%, and the oxygen concentration is preferably 0.1 to 1 vol%.
[0015]
In order to shorten the activation treatment time after the heat treatment, the porous spherical oxidation pitch is preliminarily activated at 750 to 1000 ° C. in a gas atmosphere mainly composed of water vapor until the bulk density becomes 0.6 g / mL or more ( A spherical activated carbon precursor obtained by pre-activation treatment can also be used as a raw material before heat treatment. Here, as the gas atmosphere mainly composed of water vapor, for example, an inert gas (for example, nitrogen, argon, helium, or a mixture thereof) containing water vapor of 40 to 70 vol% can be used.
[0016]
The purpose of adding the aromatic compound to the raw material pitch is to improve the fluidity of the raw material pitch to facilitate microsphere formation and to extract and remove the additive from the formed pitch product. The object is to make the molded body porous and to facilitate structure control and firing in the subsequent steps. As such an additive, for example, naphthalene, methylnaphthalene, phenylnaphthalene, benzylnaphthalene, methylanthracene, phenanthrene, or biphenyl can be used alone, or a mixture of two or more thereof can be used. The addition amount with respect to the pitch is preferably in the range of 10 to 50 parts by weight of the aromatic compound with respect to 100 parts by weight of the pitch.
[0017]
In order to achieve uniform mixing, it is preferable to mix the pitch and the additive in a molten state by heating. The mixture of pitch and additive is preferably formed into particles having a particle diameter of about 0.1 to 1 mm in order to control the particle diameter (diameter) of the obtained spherical activated carbon. Molding may be performed in a molten state, or may be performed by a method such as grinding the mixture after cooling.
[0018]
Examples of the solvent for extracting and removing the additive from the mixture of pitch and additive include, for example, aliphatic hydrocarbons such as butane, pentane, hexane, or heptane, and aliphatic hydrocarbons such as naphtha or kerosene. Or a mixture of aliphatic alcohols such as methanol, ethanol, propanol, or butanol.
By extracting the additive from the mixture molded product of pitch and additive with such a solvent, the additive can be removed from the molded product while maintaining the shape of the molded product. At this time, it is presumed that an additive loophole is formed in the molded body, and a pitch molded body having uniform porosity is obtained.
[0019]
The surface of the spherical activated carbon of the present invention obtained by the above production method is coated, for example, by the method described in Japanese Patent Publication No. 55-49868 or Japanese Patent Publication No. 58-41066. Can be obtained. Specifically, for example, the spherical activated carbon according to the present invention is subjected to a base coating treatment with a hydrophobic polymer material to form a base coating layer, and then a top coating treatment is performed with a hydrophilic polymer material. An adsorbent for direct perfusion can be obtained by forming a layer and, if necessary, cross-linking the upper coating layer.
[0020]
As described above, the spherical activated carbon according to the present invention can be used as an adsorbent for direct perfusion of a blood sample by coating the surface thereof. However, after the spherical activated carbon according to the present invention is processed as it is or after being appropriately processed, for example, water treatment, air purification, deodorization, purification of industrial chemicals, food purification, food decolorization, solvent recovery, as in general activated carbon It can also be used to recover catalysts, precious metals, or hazardous substances such as dioxins.
[0021]
As described above, the adsorbent for direct perfusion of blood sample can be used, for example, for direct blood perfusion (DHP). Here, the “blood sample” includes not only blood (whole blood) but also plasma. Therefore, the adsorbent for direct perfusion of blood sample can be used not only for in vitro treatment of blood (whole blood) but also for in vitro treatment of plasma.
[0022]
Various physical properties of the spherical activated carbon according to the present invention, that is, diameter (average particle diameter), pore volume, bulk density, specific surface area, underwater shaking wear rate, and vitamin B ₁₂ The adsorption rate is measured by the following method.
(1) Average particle size
For spherical activated carbon, a cumulative particle size diagram is prepared according to JIS K 1474. For the average particle diameter, in the particle size cumulative diagram, the horizontal line is drawn on the horizontal axis from the intersection of the vertical line at the 50% point on the horizontal axis and the particle size cumulative line to obtain the mesh size (mm) of the sieve indicated by the intersection. The average particle size.
[0023]
(2) Pore volume by mercury porosimetry
The pore volume can be measured using a mercury porosimeter (for example, “AUTOPORE 9200” manufactured by MICROMERITICS). Spherical activated carbon as a sample is put in a sample container and deaerated at a pressure of 2.67 Pa or less for 30 minutes. Next, mercury is introduced into the sample container and gradually pressurized to press the mercury into the pores of the spherical activated carbon sample (maximum pressure = 414 MPa). From the relationship between the pressure at this time and the amount of mercury injected, the pore volume distribution of the spherical activated carbon sample is measured using the following equations.
Specifically, the volume of mercury injected into the spherical activated carbon sample from a pressure corresponding to a pore diameter of 15 μm (0.07 MPa) to a maximum pressure (414 MPa: corresponding to a pore diameter of 3 nm) is measured. The pore diameter is calculated when mercury is pressed into a cylindrical pore having a diameter (D) at a pressure (P), where the surface tension of mercury is “γ” and the contact angle between the mercury and the pore wall is “ θ ”, from the balance between the surface tension and the pressure acting on the pore cross section, the following formula:
−πDγcos θ = π (D / 2) ² ・ P
Holds. Therefore
D = (− 4γcos θ) / P
It becomes.
In this specification, the surface tension of mercury is 484 dyne / cm, the contact angle between mercury and carbon is 130 degrees, the pressure P is MPa, and the pore diameter D is expressed in μm.
D = 1.27 / P
To obtain the relationship between the pressure P and the pore diameter D. In the present specification, the pore volume having a pore diameter in the range of 5 to 1000 nm corresponds to the volume of mercury that is intruded to a mercury intrusion pressure of 1.27 to 254 MPa.
[0024]
(3) Bulk density
The sample spherical activated carbon is dried for 3 hours in a drier adjusted to 115 ° C., and then allowed to cool in a desiccator. The dried spherical activated carbon sample is placed in a packing density measurement container (the container shown in FIG. 8 of JIS K 1474-5.7) to about 1/5 volume of the volume of the container. Gently tap on the rubber plate until the upper surface of the spherical activated carbon sample reaches a certain height, and add the same amount of spherical activated carbon sample and tap gently. This tapping and filling operation is repeated, the spherical activated carbon sample is filled to the upper end of the container, the tube at the top of the container is removed, the raised part is scraped off using a stainless steel straight ruler, and the upper surface of the spherical activated carbon sample is leveled. Measure the mass of the spherical activated carbon sample in the container to the order of 0.1 g. Subsequently, the packing density (L) is calculated by the following equation.
L = S / M
In the above equation, L is the bulk density (g / mL), S is the mass (g) of the spherical activated carbon sample, and M is the volume (mL) of the packing density measuring container.
[0025]
(4) Specific surface area
Measure the amount of gas adsorbed on a spherical activated carbon sample using a continuous flow gas adsorption method (for example, “Flow Sorb II 2300” manufactured by MICROMERITICS) and calculate the specific surface area using the BET equation. Can do. Specifically, a sample tube is filled with spherical activated carbon, and the following operation is performed while flowing a helium gas containing 30 vol% nitrogen into the sample tube to determine the amount of nitrogen adsorbed on the spherical activated carbon sample. That is, the sample tube is cooled to −196 ° C., and nitrogen is adsorbed on the spherical activated carbon sample. The sample tube is then returned to room temperature. At this time, the amount of nitrogen desorbed from the spherical activated carbon sample is measured with a heat conduction detector and is defined as the amount of adsorbed gas (v).
Approximate expression derived from BET equation:
v _m = 1 / (v · (1-x))
Using a one-point method with nitrogen adsorption (relative pressure x = 0.3) at liquid nitrogen temperature using _m And the following formula:
Specific surface area = 4.35 × v _m = (M ² / G)
To calculate the specific surface area of the sample. In each of the above formulas, v _m Is the amount of adsorption (cm) required to form a single molecular weight on the sample surface ^Three / G), and v is the actually measured adsorption amount (cm ^Three / G) and x is the relative pressure.
[0026]
(5) Underwater shaking wear rate
A membrane filter is attached to the filtration device, and water contained in the membrane filter is suction filtered. The membrane filter is removed, and the membrane filter is dried for 30 minutes in a drier adjusted to 115 ° C. After cooling for 30 minutes in a desiccator, the mass of the membrane filter is measured to the order of 0.1 mg.
On the other hand, spherical activated carbon (about 50 mL) as a sample is dried in a constant temperature dryer adjusted to 115 ° C. for 3 hours and then allowed to cool in a desiccator. About 10 g of the dried spherical activated carbon sample is measured to the order of 0.1 mg, and the measured value is defined as the spherical activated carbon sample mass (S). Subsequently, the spherical activated carbon sample is transferred to a shaker bottle, 50 mL of water is added, and shaken at a shake number of 245 ± 5 r / min for 30 minutes. The sample liquid obtained by filtering through a sieve and removing the large granular spherical activated carbon sample is suction filtered with a filtration apparatus to which the membrane filter whose mass has been measured is attached. The mass of the membrane filter to which the powdery filtration residue is adhered is measured, transferred to a bottle, and dried for 30 minutes in a drier adjusted to 115 ° C. After cooling for 30 minutes with a desiccator, the dry mass of the membrane filter to which the powdery filtration residue is adhered is measured to the order of 0.1 mg, and the amount of powdery filtration residue (R) is determined. The underwater shaking wear rate (A) is calculated by the following equation.
A = (R / S) × 100
In the above formula, A is the underwater shaking wear rate (%), R is the mass of the filtration residue (g), and S is the mass (g) of the spherical activated carbon sample.
[0027]
(6) Vitamin B ₁₂ Adsorption removal ability
About 5 g of the spherical activated carbon sample is dried for 3 hours in a constant temperature dryer adjusted to 115 ° C., and then allowed to cool in a desiccator. Vitamin B in the beaker for adsorption test in advance ₁₂ Vitamin B with known concentration (F) ₁₂ Put the standard stock solution in exactly 100 mL. Then, it is immersed in a water bath adjusted to 37 ° C. Vitamin B ₁₂ When the temperature of the standard stock solution reaches 37 ° C, a dry spherical activated carbon sample is weighed to the order of 0.1 mg within a range of 1 ± 0.001 g, placed in a beaker, and stirred for 30 minutes at a rotation speed of 405 r / min. And filter. For the obtained filtrate and standard stock solution, the absorbance at a wavelength of 520 nm is measured using a spectrophotometer. A calibration curve is prepared from the absorbance of the standard stock solution, and vitamin B is determined from the absorbance of the filtrate. ₁₂ The residual concentration (E) is determined. Vitamin B ₁₂ The adsorption removal rate (D) is calculated by the following equation.
D (%) = [(10−E) / F] × 100
In the above formula, D is vitamin B ₁₂ Adsorption removal rate (%), E is vitamin B ₁₂ Residual concentration (mg / 100 mL) and F is vitamin B ₁₂ Stock solution concentration (mg / 100 mL).
[0028]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.
[0029]
[Example 1]
68 kg of petroleum-based pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63) and 32 kg of naphthalene are charged into a pressure-resistant container having a stirring capacity of 300 L. After melt mixing at 180 ° C., the mixture was cooled to 80 to 90 ° C. and extruded to obtain a string-like molded body. Next, the string-like molded body was crushed so that the ratio of diameter to length was about 1-2. To this crushed material, 120 kg of 0.23% by weight aqueous solution of polyvinyl alcohol (saponification degree = 88%) was added and dispersed by stirring at 95 ° C. at a speed of 350 rpm, and then rapidly cooled to solidify the dispersed particles. A spherical pitch molded body was obtained.
Further, filtration was performed to remove moisture, and naphthalene in the spherical pitch molded body was extracted and removed with n-hexane about 6 times the weight of the spherical pitch molded body. Subsequently, oxidation treatment was performed in air at 260 ° C. for 1 hour to obtain an infusible porous spherical oxidation pitch.
Next, the infusible porous spherical oxide pitch was baked at 1350 ° C. for 4 hours in a nitrogen gas atmosphere. Furthermore, activation treatment was performed at 820 ° C. for 12 hours in a nitrogen gas atmosphere containing 50 vol% water vapor and 0.5 vol% oxygen to obtain spherical activated carbon according to the present invention.
[0030]
[Example 2]
Except that the activation treatment was performed at 900 ° C. for 5 hours, the operation described in Example 1 was repeated to obtain a spherical activated carbon according to the present invention.
[0031]
[Example 3]
A spherical activated carbon according to the present invention was obtained by repeating the operation described in Example 1 except that the firing treatment was performed at 2000 ° C. and the activation treatment was performed at 900 ° C. for 10 hours.
[0032]
[Example 4]
A spherical activated carbon according to the present invention was obtained by repeating the operation described in Example 1 except that the firing treatment was performed at 1100 ° C. and the activation treatment was performed at 900 ° C. for 4 hours.
[0033]
[Example 5]
68 kg of petroleum-based pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63) and 32 kg of naphthalene are charged into a pressure-resistant container having a stirring capacity of 300 L. After melt mixing at 180 ° C., the mixture was cooled to 80 to 90 ° C. and extruded to obtain a string-like molded body. Next, the string-like molded body was crushed so that the ratio of diameter to length was about 1-2. To this crushed material, 120 kg of 0.23% by weight aqueous solution of polyvinyl alcohol (saponification degree = 88%) was added and dispersed by stirring at 95 ° C. at a speed of 350 rpm, and then rapidly cooled to solidify the dispersed particles. A spherical pitch molded body was obtained.
Further, filtration was performed to remove moisture, and naphthalene in the spherical pitch molded body was extracted and removed with n-hexane about 6 times the weight of the spherical pitch molded body. Subsequently, oxidation treatment was performed in air at 260 ° C. for 1 hour to obtain an infusible porous spherical oxidation pitch.
Next, the obtained infusible porous spherical oxidized pitch is subjected to a pre-activation treatment in nitrogen gas containing 50 vol% of water vapor until the bulk density becomes 0.6 g / mL or more, and thus a spherical activated carbon precursor. Got. It can be confirmed that the bulk density is 0.6 g / mL or more by taking a part of the spherical activated carbon precursor from the preliminary activation furnace during the preliminary activation treatment and measuring the bulk density.
Next, the spherical activated carbon precursor was calcined at 1350 ° C. for 4 hours in a nitrogen gas atmosphere. Furthermore, activation treatment was performed at 900 ° C. for 4 hours in a nitrogen gas atmosphere containing 50 vol% water vapor and 0.5 vol% oxygen to obtain spherical activated carbon according to the present invention.
[0034]
[Example 6]
Except that the activation treatment time was 7 hours, the operation described in Example 5 was repeated to obtain spherical activated carbon according to the present invention.
[0035]
[Example 7]
Except that the heat treatment temperature was 2000 ° C. and the activation treatment time was 10 hours, the operation described in Example 5 was repeated to obtain spherical activated carbon according to the present invention.
[0036]
[Example 8]
Except that the heat treatment temperature was 1100 ° C. and the activation treatment time was 7 hours, the operation described in Example 5 was repeated to obtain spherical activated carbon according to the present invention.
[0037]
[Comparative Example 1]
68 kg of petroleum-based pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63) and 32 kg of naphthalene are charged into a pressure-resistant container having a stirring capacity of 300 L. After melt mixing at 180 ° C., the mixture was cooled to 80 to 90 ° C. and extruded to obtain a string-like molded body. Next, the string-like molded body was crushed so that the ratio of diameter to length was about 1-2. To this crushed material, 120 kg of 0.23% by weight aqueous solution of polyvinyl alcohol (saponification degree = 88%) was added and dispersed by stirring at 95 ° C. at a speed of 350 rpm, and then rapidly cooled to solidify the dispersed particles. A spherical pitch molded body was obtained.
Further, filtration was performed to remove moisture, and naphthalene in the spherical pitch molded body was extracted and removed with n-hexane about 6 times the weight of the spherical pitch molded body. Subsequently, oxidation treatment was performed in air at 260 ° C. for 1 hour to obtain an infusible porous spherical oxidation pitch.
Next, the infusible porous spherical oxide pitch was baked at 820 ° C. for 0.5 hours in a nitrogen gas atmosphere. Furthermore, activation treatment was performed at 820 ° C. for 2 hours in a nitrogen gas atmosphere containing 50 vol% water vapor and 0.5 vol% oxygen to obtain a comparative spherical activated carbon.
[0038]
[Comparative Example 2]
68 kg of petroleum-based pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63) and 32 kg of naphthalene are charged into a pressure-resistant container having a stirring capacity of 300 L. After melt mixing at 180 ° C., the mixture was cooled to 80 to 90 ° C. and extruded to obtain a string-like molded body. Next, the string-like molded body was crushed so that the ratio of diameter to length was about 1-2. To this crushed material, 120 kg of 0.23% by weight aqueous solution of polyvinyl alcohol (saponification degree = 88%) was added and dispersed by stirring at 95 ° C. at a speed of 350 rpm, and then rapidly cooled to solidify the dispersed particles. A spherical pitch molded body was obtained.
Further, filtration was performed to remove moisture, and naphthalene in the spherical pitch molded body was extracted and removed with n-hexane about 6 times the weight of the spherical pitch molded body. Subsequently, oxidation treatment was performed in air at 260 ° C. for 1 hour to obtain an infusible porous spherical oxidation pitch.
Next, the obtained infusible porous spherical oxidized pitch is subjected to a pre-activation treatment in nitrogen gas containing 50 vol% of water vapor until the bulk density becomes 0.6 g / mL or more, and thus a spherical activated carbon precursor. Got. It can be confirmed that the bulk density is 0.6 g / mL or more by taking a part of the spherical activated carbon precursor from the preliminary activation furnace during the preliminary activation treatment and measuring the bulk density.
Next, the spherical activated carbon precursor was baked at 1350 ° C. for 4 hours in a nitrogen gas atmosphere. Furthermore, activation treatment was carried out at 900 ° C. for 6 hours in a nitrogen gas atmosphere containing 50 vol% water vapor and no oxygen at all to obtain a spherical activated carbon for comparison.
[0039]
[Comparative Example 3]
A spherical activated carbon for comparison is obtained by repeating the operation described in Comparative Example 2 except that the activation treatment is performed for 1 hour in a nitrogen gas atmosphere containing 50 vol% water vapor and 0.5 vol% oxygen. It was.
[0040]
[Comparative Example 4]
The addition of 0.01 wt% cobalt to petroleum pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63) and naphthalene, and the activation treatment time is 1 hour Except that, the operation described in Comparative Example 1 was repeated to obtain a comparative spherical activated carbon.
[0041]
[Comparative Example 5]
Instead of petroleum pitch (softening point = 210 ° C., quinoline insoluble content = 1 wt% or less, H / C atomic ratio = 0.63), another petroleum pitch (softening point = 192 ° C., quinoline insoluble content = 34 Spherical activated carbon for comparison was obtained by repeating the operation described in Comparative Example 1 except that .2 wt% or less, H / C atomic ratio = 0.53) was used.
[0042]
The production conditions described in Examples 1 to 8 and Comparative Examples 1 to 5 are summarized in Table 1 below.
[0043]
[Table 1]

[0044]
【Evaluation of the physical properties】
About the spherical activated carbon obtained based on the manufacturing conditions described in Examples 1 to 8 and Comparative Examples 1 to 5, the diameter (average particle diameter), pore volume, bulk density, specific surface area, H / C, Underwater shaking wear rate and vitamin B ₁₂ The adsorption rate was measured. Each physical property value was measured by the measurement method described above. The obtained physical property values are summarized in Table 2.
[0045]
[Table 2]

[0046]
Each of the spherical activated carbons of the present invention obtained in Examples 1 to 8 has a water abrasion wear rate that can be sufficiently used as a spherical activated carbon for direct perfusion of blood. ₁₂ The adsorptive removal ability of was also high.
On the other hand, in the comparative spherical activated carbon obtained in Comparative Examples 1 to 3, the underwater shaking wear rate was a value that could be sufficiently used as the spherical activated carbon for direct blood perfusion. ₁₂ The adsorptive removal ability was not sufficient. Moreover, in the comparison spherical activated carbon obtained in Comparative Example 4, vitamin B ₁₂ Although the adsorbing and removing ability of the sample showed a sufficient value, it has a high rate of underwater shaking wear and is not suitable as a spherical activated carbon for direct perfusion of blood. In addition, the comparative spherical activated carbon obtained in Comparative Example 5 has an underwater shaking wear rate and vitamin B ₁₂ The adsorbing and removing ability of each is insufficient.
[0047]
【The invention's effect】
According to the novel spherical activated carbon according to the present invention, the ability of adsorbing a substance having a relatively large molecular weight can be obtained without impairing various physical properties that have been achieved in the conventionally known activated carbon used as a raw material for the adsorbent used in the direct blood perfusion method. In addition, the underwater shaking wear rate is also improved.

Claims

A diameter of 0.1 to 1 mm, H / C is 0.14 or less, the pore volume of the fine pore diameter 5~1000nm is 0.25~0.55mL / g der is, and water shaking wear rate Spherical activated carbon for direct perfusion of blood, characterized in that is 0.08% by weight or less .

The spherical activated carbon for direct perfusion of blood according to claim 1, wherein the bulk density is 0.40 to 0.55 g / mL.

Adsorption rate of vitamin B ₁₂ is 93% or more, direct perfusion spherical activated carbon of blood according to claim 1 or 2.

The porous spherical oxidized pitch or the spherical activated carbon precursor is heat-treated at 1000 to 2500 ° C. in an inert gas atmosphere, and subsequently activated at 750 to 1200 ° C. in a mixed gas atmosphere of water vapor, oxygen and inert gas. The method for producing spherical activated carbon for direct perfusion of blood according to any one of claims 1 to 3, wherein the method is performed.

The porous spherical oxide pitch is
A step of adding a bicyclic or tricyclic aromatic compound having a boiling point of 200 ° C. or higher to an isotropic pitch, heating and mixing, and then molding to obtain a pitch molded body;
Dispersing and granulating the pitch compact in hot water and cooling to microspheres to obtain a microsphere pitch product; and
A porous sphere obtained by extracting and removing the additive from the microspherical pitch-formed product using a solvent having low solubility with respect to pitch and having high solubility with respect to the aromatic compound or a mixture thereof. Oxidizing the pitch with an oxidizing agent;
The method for producing a spherical activated carbon for direct perfusion of blood according to claim 4, which is a porous spherical oxidized pitch obtained by: