JP2004351288A - Method for treating heavy-metal containing water or heavy-metal-containing soil - Google Patents
Method for treating heavy-metal containing water or heavy-metal-containing soil Download PDFInfo
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- JP2004351288A JP2004351288A JP2003150421A JP2003150421A JP2004351288A JP 2004351288 A JP2004351288 A JP 2004351288A JP 2003150421 A JP2003150421 A JP 2003150421A JP 2003150421 A JP2003150421 A JP 2003150421A JP 2004351288 A JP2004351288 A JP 2004351288A
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- heavy metal
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- metal ion
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- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 120
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 title claims abstract description 53
- 239000002689 soil Substances 0.000 title claims abstract description 22
- 239000000835 fiber Substances 0.000 claims abstract description 110
- 229910052751 metal Inorganic materials 0.000 claims abstract description 92
- 239000002184 metal Substances 0.000 claims abstract description 92
- 238000001179 sorption measurement Methods 0.000 claims abstract description 36
- 239000002253 acid Substances 0.000 claims abstract description 20
- SFZULDYEOVSIKM-UHFFFAOYSA-N chembl321317 Chemical group C1=CC(C(=N)NO)=CC=C1C1=CC=C(C=2C=CC(=CC=2)C(=N)NO)O1 SFZULDYEOVSIKM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 125000000524 functional group Chemical group 0.000 claims abstract description 11
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- 229910021645 metal ion Inorganic materials 0.000 abstract description 13
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- 125000004093 cyano group Chemical group *C#N 0.000 description 13
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
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- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
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- Processing Of Solid Wastes (AREA)
- Treatment Of Water By Ion Exchange (AREA)
Abstract
Description
【0001】
【発明の属する技術分野】
本発明は、Pb、Cd、Znなどの重金属を含有する水及び土壌、中でも精錬所等の工場からの重金属含有水中の重金属を効果的に除去する処理方法に関する。
【0002】
【従来の技術】
重金属イオン含有水の処理方法としては、中和凝集沈殿法、イオン浮選法、イオン交換法、電解浮上法、電気透析法、吸着法、逆浸透法、金属捕集剤を用いる方法等が知られている。
【0003】
中和凝集沈殿法は、アルカリ剤を用いて重金属含有水(被処理水)を中和するとともに、重金属イオンを水酸化物の形にしてゼオライト、シリカゲルなどを用いて吸着除去する方法であるが、アルカリ剤を多量に必要とする上、金属水酸化物スラッジが大量に生じるという課題を抱えていた。
【0004】
また、金属捕集剤を用いる方法は、チオ尿素、オキシン、ジフェニルカルバジド、チオグリコール酸、ジメチルグリオキシム、スルファミン酸グアニジンなどの金属捕集剤を水等に溶解させて対象とする被処理水に添加し、当該被処理水中に含まれる金属と金属捕集剤とを反応させて生成したフロックを分離除去して金属を捕集する方法である(特開2001−115137参照)が、この方法も金属捕集剤を多量に必要とする上、大量のフロックが生じるという課題を抱えていた。
【0005】
そこで本発明は、大量のスラッジやフロックが生じず比較的小規模な施設で簡便に行なうことでき、しかも重金属の除去効率が高い方法として、イオン交換樹脂やキレート樹脂などを用いて被処理水中の重金属を直接吸着除去する方法に注目した。
【0006】
この種の処理方法として、例えば特許文献1は、被処理水中の重金属イオンを、キレート基を側鎖に備えた多孔性膜を用いて、イオン濃度が初期濃度の1/10以下になるまで濾過処理することを特徴とする重金属除去方法を開示している。
【0007】
また、特許文献2及び特許文献3は、被処理水中に含有される重金属を、キレート高分子を備えた繊維状物と接触させることにより除去する方法において、そのキレート高分子を備えた繊維状物として、弱酸性のキレート官能基を有するキレート高分子と弱塩基性のキレート官能基を有するキレート高分子とから構成された繊維状物を提案し、このキレート高分子から成る充填層に重金属含有被処理水を通水して重金属をキレート高分子と接触させる方法を開示している。
【0008】
また、特許文献4は、同じく被処理水中に含有される重金属を接触させる高分子成型体として、放射線照射を行うことにより、オレフィン又はハロゲン化オレフィンの重合体又は共重合体からなる繊維、織布又は不織布にアミノ酸をグラフト重合して固定化した高分子成型体を開示している。
【0009】
さらに特許文献5は、放射線照射グラフト重合法により、親水基を含有する重合性モノマーの存在下で、シアノ基を含有する重合性モノマーをポリオレフィン繊維にグラフト重合させ、親水基及びシアノ基を同一グラフト重合側鎖を形成し、そのグラフト重合側鎖のシアノ基にヒドロキシルアミンを反応させてアミドキシム基に変換してなる溶存金属捕集材を開示している。
【0010】
【特許文献1】
特開平3−16601号
【特許文献2】
特開平5−57280号
【特許文献3】
特開平5−57281号
【特許文献4】
特開平5−111685号
【特許文献5】
特開2000−176279号
【0011】
【発明が解決しようとする課題】
本発明の目的は、被処理液或いは被処理土壌中の重金属をキレート樹脂を用いて吸着除去する処理方法において、より効率的で簡易であって、しかもZn、Cd、Pbの吸着能力をより一層高め得る処理方法を提供することにある。
【0012】
【課題解決手段】
本発明は、キレート官能基としてアミドキシム基を備えた金属イオン吸着繊維に重金属含有水を接触させて当該金属イオン吸着繊維に重金属を吸着させる吸着工程と、重金属を吸着した金属イオン吸着繊維を酸溶液と接触させて当該金属イオン吸着繊維を洗浄する逆洗工程とを備えた重金属含有液の処理方法を提案する。
【0013】
このような処理方法であれば、スラッジやフロックなどを処理途中で生じさせないため処理手順及び施設などを簡便化・小型化することでき、かつ処理速度が速いため処理効率を高めることができる。しかも従来用いられているキレート樹脂を用いた水のイオン交換処理法に比べ、大量の液処理に適しており、特に精錬所からの重金属含有水の処理方法として優れている。中でも特に、従来公知の処理方法にて重金属濃度を0.1ppm〜100ppm程度まで低下させた後の二次処理法として特に優れている。
なお、金属イオン吸着繊維に重金属含有水を接触させて当該金属イオン吸着繊維に重金属を吸着させる吸着工程のみを独立して行なうことも可能である。重金属を吸着させた金属イオン吸着繊維は、そのまま運搬することができるから、たとえば山間部などの大規模な処理施設を建設することが難しい場所では吸着工程のみ実施する処理施設を設けておき、重金属を吸着させた金属イオン吸着繊維は別の処理施設に運搬してその後の処理を行うことができる。
【0014】
上記の処理方法において、被処理液中の重金属濃度が高い場合には、洗浄工程で生じた洗浄排液中の重金属を濃縮する濃縮工程と、前記濃縮工程で得た重金属濃縮液を中和する中和工程とを追加するのが好ましい。
このような濃縮工程によって中和処理量が減少し、これにより中和処理剤量の減少および中和廃棄物量の減少を図ることができる。
【0015】
また、上記重金属含有液の処理方法の方法において、吸着工程前に重金属含有水のpHを測定し、当該重金属含有水のpHを約5〜7に調整した上で吸着工程に供給するようにするのが好ましい。キレート官能基としてアミドキシム基を備えた金属イオン吸着繊維、中でもアミドキシム基付近に親水基を共存する金属イオン吸着繊維は、pH約5〜7の範囲で重金属吸着能力を最も発揮することを本発明者は確認している。
【0016】
上記の重金属含有水の処理方法を応用して重金属含有土壌を好適に処理することができる。すなわち、重金属含有土壌をpH5〜7の酸溶液に浸漬し、その上澄み液を必要に応じて濾過して酸溶液から重金属含有水を得、この重金属含有水を上記の処理方法にて処理すれば、重金属含有土壌も上記同様に効率良く処理することができる。しかも、重金属含有水のpHが約5〜7で最も効果的に重金属を吸着除去することができるから、pH約5〜7の酸溶液、好ましくは酢酸、クエン酸などの有機酸溶液に重金属含有土壌を浸漬処理することができ、そればかりか、そのようにすれば、その後pH調整せずに吸着工程に供給することができ、しかも最も効果的に重金属を吸着除去することができ、より一層環境に優しい再生土壌をも得ることができる。
【0017】
なお、「重金属」とは、一般に金(Au)、白金(Pt)、銀(Ag)、銅(Cu)、水銀(Hg)、スズ(Sn)、カドミウム(Cd)、鉛(Pb)、鉄(Fe)、亜鉛(Zn)など、比重が4〜5以上の金属を重金属という。
また、本発明において「重金属含有水」とは、重金属を含有する水全般を包含し、例えば精錬所などの工場、ごみ焼却場、研究所、病院などからの重金属含有水、海水、地熱水、油井水、一般排水などを包含する。
また、本発明において「重金属含有土壌」とは、重金属を含有する土壌全般を包含し、例えばゴミ焼却場で生じる焼却灰、汚水処理場等において使用した処理済みの汚泥、工場跡地の土壌などを包含する。
【0018】
【発明の実施の形態】
次に、本発明の実施の形態について説明する。
【0019】
本発明の一例に係る重金属含有液の処理方法は、必要に応じて重金属含有水のpHを測定して所定範囲にpH調整を行った後(pH調整工程)、重金属含有水を金属イオン吸着繊維に接触させて重金属を金属イオン吸着繊維に吸着させ(吸着工程)、吸着した重金属を金属イオン吸着繊維から離脱させ(逆洗工程)、必要に応じて前記工程で得られた洗浄排液中の重金属を濃縮し(濃縮工程)、必要に応じて濃縮した重金属濃縮液を中和する(中和工程)工程を経て実施することができる。
以下、より詳細に説明する。
【0020】
(金属イオン吸着繊維)
本発明で用いる吸着材は、キレート官能基としてアミドキシム基を備えた金属イオン吸着繊維である。
このような金属イオン吸着繊維は、例えば基材繊維に電子線を照射して繊維分子の動きを活発にして反応性を高めた後(反応開始種としてのラジカルを生成させ)、重合性モノマーをグラフト重合させ、このグラフト重合側鎖にヒドロキシルアミンを反応させて金属捕集能を有するアミドキシム基を導入する製造方法によって得ることができる。但し、この製法に限定するものではない。
基材繊維としては、ポリエチレン、ポリプロピレン、ポリスルホン、ポリテトラフルオロエチレン、その他の高分子からなる繊維を用いることができる。中でも、ポリエチレン及びポリプロピレンはグラフト重合を施し易いため好ましい。照射する放射線としては、α線、β線、γ線、X線、加速電子線等を挙げることができ、その照射線量は100〜200kGy、雰囲気としては空気中或いは不活性ガス中で−50〜0℃とするのが好ましい。
重合性モノマーとしては、例えばアクリロニトリル、メタクリル酸、グリシジルメタクリレート、アクリル酸、スチレンスルホン酸ナトリウムのいずれか、或いはそれらの二種類以上の組合わせからなる混合物を用いることができる。混合物としては、アクリロニトリルとメタクリル酸との混合物やグリシジルメタクリレートとアクリル酸との混合物などを挙げることができる。但しこれらに限定されるものではない。
【0021】
本発明の処理で用いる金属イオン吸着繊維としては、上記の中でも、同一又は異なる重合側鎖にアミドキシム基と親水基とを備えた金属イオン吸着繊維が好ましい。
このような金属イオン吸着繊維は、例えば、上記同様基材繊維に電子線を照射した後、親水基を有する重合性モノマーをグラフト重合し、更にシアノ基を有するモノマーを重合するか、或いは、親水基を有する重合性モノマーの存在下でシアノ基を有するモノマーをグラフト重合する製造方法によって得ることができる。具体的には、特開2000−176279号及び特開2000−178531号に開示された方法により得ることができる。すなわち、例えば基材繊維に電子線を照射し、親水基を有する重合性モノマーの存在下で、アクリロニトリル等のシアノ基を有する重合性モノマーを基材繊維にグラフト重合し、グラフト重合側鎖中のシアノ基にヒドロキシルアミンを反応させてシアノ基をアミドキシム基に変換させることにより得ることができる。また、親水基を有する重合性モノマーの存在下で、アクリロニトリル等のシアノ基を有する重合性モノマーを基材繊維にグラフト重合させる際、親水基を有する重合性モノマーとシアノ基を有する重合性モノマーのモル比を調整して重合させた後、グラフト重合側鎖中のシアノ基にヒドロキシルアミン(NH2OH)を反応させてシアノ基をアミドキシム基に変換させることによっても得ることができる。
この際、シアノ基を有する重合性モノマーとしては、アクリロニトリル、シアン化ビニリデン、クロトンニトリル、メタクリロニトリル、クロルアクリロニトリル、2−シアノメチルアクリレート、2−シアノエチルアクリレート又はそれらの混合物を挙げることができ、親水基を含有する重合性モノマーとしては、2−ヒドロキシエチルメタクリレート、2−ヒドロキシエチルアクリレート、アリルアルコール、ポリエチレングリコールアクリレート、ポリエチレングリコールメタクリレート、ポリエチレングリコールジアクリレート、ポリエチレングリコールジメタクリレート、N−ビニルピロリドン、又はアクリルアミドを挙げることができる。
【0022】
なお、金属イオン吸着繊維のキレート官能基としてアミドキシム基の代わりに、イミノジ酢酸基、スルホン酸基、リン酸基、2−ピロリドン基等を用いることは容易に推定できることであり、作用も同様であると容易に推定することができる。
【0023】
上記の金属イオン吸着繊維は、織布状、不織布状、膜状、管状、プリーツ状、スパイラル状、モール状その他の形状に加工して本処理に使用することができる。
接触効率を高めるため、短繊維状或いは粒子状に形成することも可能である。また、織布状或いは不織布状の金属イオン吸着繊維シートを一枚単位で使用することも可能であるが、複数枚重ねた積層物として、更には繊維シート間にスペーサーを入れて重ねた積層物として使用することも可能である。
さらにまた、簡便に交換できるようなカートリッジフィルタを形成して使用することもできる。
【0024】
上記金属イオン吸着繊維は、予め次のように前処理して重金属吸着能を高めておくのが好ましい。前処理することにより、金属イオン吸着繊維が本来備えている重金属吸着能力を最初から発揮させることができる。
【0025】
すなわち、未使用の金属イオン吸着繊維を酸溶液と接触させた後、金属イオン吸着繊維を洗浄し、次に金属イオン吸着繊維を水酸化カリウム等の金属の水酸化物水溶液に接触させて水洗処理するのが好ましい。
この際、酸溶液の接触、洗浄、金属イオン溶液の接触及び水洗処理からなる工程を繰り返し行ってもよい。
【0026】
上記前処理において、酸溶液との接触方法を特に限定するものではないが、例えば未使用の金属イオン吸着繊維を塩酸、硫酸などの酸溶液内に投入し、攪拌しながら適宜時間浸漬させるのが好ましい。
金属イオン吸着繊維の洗浄は、例えば純水或いはイオン交換水などの洗浄水中に金属イオン吸着繊維を投入し攪拌させたり、或いは洗浄水を掛け流すようにすればよいが、これらの方法に限定するものではない。
酸溶液の接触及び洗浄の工程は繰り返し行ってもよい。
【0027】
また、上記前処理において、金属イオン溶液との接触方法を特に限定するものではないが、例えば苛性カリ(KOH)溶液などの金属イオン溶液に金属イオン吸着繊維を浸漬させるようにすればよい。この際、金属イオン溶液としては、K、Na、Ca等のアルカリ金属或いはアルカリ土類金属のイオンを含有する液を用いるのが好ましく、特に金属イオン吸着繊維を浸漬させる際には80℃付近に加熱するのが好ましい。加熱することで、未使用金属イオン吸着繊維の重金属吸着能をより一層高めることができる上、処理時間を短縮することができる。
また、金属イオン溶液への浸漬は、金属イオン吸着繊維を金属イオン溶液に投入して攪拌しながら適宜時間浸漬させた後、上澄み液を除去するようにする。この工程は繰り返し行ってもよい。
その後の水洗処理は、純水或いはイオン交換水などの洗浄水中に投入して攪拌したり、洗浄水を掛け流すなどすればよい。ただし、これらの方法に限定するものではない。
【0028】
(重金属含有水のpH調整工程)
重金属含有水は、吸着工程に供給する前にそのpHを測定し、pH約5〜7に調整しておくのが好ましい。
通常のキレート官能基を備えた金属イオン吸着繊維は、pH約7以下ではキレート能力を発揮しないが、キレート官能基としてアミドキシム基を備えた金属イオン吸着繊維、中でもアミドキシム基付近に親水基を共存してなる金属イオン吸着繊維は、pH約5〜7の範囲でも効果的に重金属を吸着除去することができる。
よって、重金属含有水のpHを測定し、pHが約5より低かったならば、水酸化ナトリウム、水酸化カリウムなどのアルカリ化剤を添加してpH約5以上に調整し、その一方pHが約7より高かったならば、塩酸、硫酸、硝酸、クエン酸、酢酸、リン酸、アスコルビン酸、クエン酸などの酸類或いはその塩類(例えば炭酸ナトリウムや硫酸水素ナトリウムなど)を添加してpH約7以下に調整するのが好ましい。
なお、pH約7よりpHを高めても有効に重金属を吸着除去することはできるが、特にアミドキシム基付近に親水基を共存してなる金属イオン吸着繊維の場合、pH約5〜7の範囲で優れた重金属吸着能力を発揮することが確かめられており、pH約7より高くする必要はない。
また、pH約3以上とすることで鉄を水酸化物として沈殿させることができるから、必要に応じてpH調整工程後に固液分離工程を挿入することで鉄を予め除去することが可能であり、その場合には鉄イオンの影響なしに後工程の処理を行なうことができる。
【0029】
(吸着工程)
吸着工程では、重金属含有水を金属イオン吸着繊維と接触させ、重金属を金属イオン吸着繊維に吸着させる。また、金属イオン吸着繊維と接触後の処理済水は、必要に応じて別の濾過などの他処理を施した後、重金属除去水として適宜用途へ供給したり或いはそのまま排水することもできる。
【0030】
重金属含有水を金属イオン吸着繊維と接触させる方法としては、例えば金属イオン吸着繊維を充填したカラム内に重金属含有水を通水させたり、金属イオン吸着繊維を積層したフィルターに重金属含有水を通水させたり、或いは、重金属含有水をタンク内を貯留しておき、金属イオン吸着繊維でタンク内を攪拌して接触させたりするなど、重金属含有水が金属イオン吸着繊維と効率良く接触し得る方法であれば適宜方法を採用することができる。
この際、カラム或いはフィルタ内の金属イオン吸着繊維の充填密度、充填量、重金属含有水の流速などは適宜調整すればよい。
【0031】
(逆洗工程)
重金属を吸着した処理済み金属イオン吸着繊維は、塩酸、硫酸などの強酸で洗浄することにより重金属を金属イオン吸着繊維から離脱させ、再生した金属イオン吸着繊維と重金属を含有した洗浄排液とを得る。
【0032】
逆洗方法は、従来公知の方法を採用可能であるが、好ましくは重金属を吸着した処理済み金属イオン吸着繊維を塩酸、硫酸などの強酸溶液(溶離液)に浸漬し、純水で強酸溶液(溶離液)を洗浄した後、当該金属イオン吸着繊維を苛性カリ(KOH)溶液などの金属イオン溶液に浸漬して水洗処理して、重金属を含有した洗浄排液と、再生した金属イオン吸着繊維とを得るようにすればよい。
この際、溶離液への浸漬及び酸溶液除去の工程は、1回でもよいが、複数回繰り返すのが好ましい。また、例えば溶離液の濃度を順に高くするようにして酸と多段階で接触させるようにしてもよい。
溶離液の種類は、回収する金属の種類や回収した金属の精製方法、溶離のし易さ、官能基の種類や耐久性などによって適宜選択するのが好ましい。
また、金属イオン溶液としては。K、Na、Ca等のアルカリ金属或いはアルカリ土類金属のイオンを含有する液を用いるのが好ましく、特に金属イオン吸着繊維を浸漬させる金属イオン溶液を約70〜80℃、好ましくは80℃付近に加熱するのが好ましい。加熱することで、未使用金属イオン吸着繊維同様、次回の重金属吸着能をより一層高めることができる上、処理時間を短縮することができる。
金属イオン吸着繊維を金属イオン溶液に浸漬して水洗処理する際、好ましくは金属イオン溶液に金属イオン吸着繊維を投入して攪拌しながら適宜時間浸漬させた後、上澄み液を除去するようにすればよく、好ましくはこの工程を2回以上繰り返すようにするのがよい。
【0033】
(濃縮工程)
逆洗工程で得られた重金属含有洗浄排液は、必要に応じて濃縮する。濃縮方法としては現在公知の任意の方法を採用すればよく、例えば沈降濃縮法、電気透析法などを好ましい例として挙げることができる。
【0034】
(中和工程)
前記工程で得られた重金属濃縮液は、必要に応じて、水酸化ナトリウムや炭酸ナトリウム等のアルカリ金属水酸化物や炭酸塩などを添加して中和処理する。
アルカリ金属水酸化物や炭酸塩などと反応させることで難溶性化合物を生成させ、濾過等により容易に固液分離できるようになる。例えば石灰等で中和処理すれば重金属炭酸塩等の沈殿物を得ることができる。
中和後の処理水は、pH8〜12、好ましくは10〜11の弱アルカリ性となるようにするのが好ましい。pHが高いほど金属化合物の分離を効率良く行うことができる。
【0035】
(重金属の回収)
逆洗工程で得られた重金属含有洗浄排液或いは前記工程で中和された重金属含有濃縮液は、必要に応じて、固液分離処理を施して重金属を回収する。ただし、重金属を回収しなくても、重金属を高濃度に含有する液のまま処理することも可能である。
【0036】
(重金属含有土壌の洗浄)
重金属含有土壌は、酸に浸漬してその上澄み液を得、その上澄み液を必要に応じて濾過及びpH5〜7に調整した後、その上澄み液を上記の重金属含有水と同様に処理することにより、重金属を除去した土壌として再生することができる。この際、重金属含有土壌をクエン酸、酢酸などのpH5〜7の有機酸に浸漬するようにすれば、後工程でpH調整する必要がないばかりか、より環境に優しい土壌として再生することができる。
【0037】
なお、上記の重金属含有水或いは重金属含有土壌の処理おいて、上記以外の工程を挿入すること、或いは工程の順序を入れ替えることは適宜可能である。
【0038】
(試験1)
試料溶液としてpH約7の精錬所からの重金属含有水(Zn濃度110mg/L、Cd濃度20mg/L)を用意し、バッチ試験を行った。
【0039】
金属イオン吸着繊維(実施例繊維)として、同一グラフト重合側鎖内にアミドキシム基と親水基とが共存してなる金属イオン吸着繊維を用意した。
この金属イオン吸着繊維は、ポリエチレン不織布に電子加速器を使用して窒素雰囲気下で200kGy照射した後、照射繊維を窒素バブリングしたアクリロニトリル(AN):メタクリル酸(MAA):ジメチルスルホキシド(DMSO)=7:3:10からなる溶液に浸漬して40℃で5時間反応させてMAA−ANグラフト繊維を得(グラフト重合率150%)、得られたMAA−ANグラフト繊維を水酸化カリウムで中和した3wt%塩酸ヒドロキシルアミンの水−メタノール溶液(水:メタノール=1:1重量比)に浸漬し、80℃1時間反応させることによって得たものである。
【0040】
また、比較する吸着材(「比較吸着材」という。)として、市販のキレート樹脂(ミヨシ油脂製MX−8C)を用意した。
【0041】
1cm角の金属イオン吸着繊維0.05g(実施例繊維)3枚を試料溶液50mL中に投入する一方、比較吸着材1.5gを試料溶液500mL中に投入し、15時間マグネットスターラーで攪拌した後、上澄液の濃度を測定し、処理前後の重金属(Zn及びCd)の濃度差から吸着量を算出した。
【0042】
この結果、吸着材(実施例繊維及び比較吸着材)1g当たりのZn及びCd吸着量は、実施例繊維が80mg、比較吸着材が22mgであった。
【0043】
(試験2)
試料溶液としてpH約7の精錬所からの重金属含有水(Zn濃度110mg/L、Cd濃度20mg/L)を用意した。
【0044】
試験1と同じ実施例繊維を1個当たり約0.3gに切り刻み、切り刻んだ実施例繊維0.3gをガラス製カラム(容積約2ml)内に詰めて、このカラム内に試料溶液をSV50(100ml/hr)の流速で流し、流出液を10mLづつのフラクションとして回収し、各フラクションのZn及びCd濃度を測定し、各元素の破過曲線を図1に示した。
また、上記の比較例繊維についても同様の試験(但し流速は、SV10(20ml/hr))を行ない、その破過曲線を図2に示した。
【0045】
この結果、比較例繊維では流速がSV10で破過曲線が乱れたのに対し、実施例繊維は流速SV50でも良好な破過曲線を示した。
【0046】
(試験3)
試験2と同様、カラムに実施例繊維を詰めて試料溶液をSV50の流速で流すようにして吸着試験を行なった後の金属イオン吸着繊維をカラムから取り出し、0.5Nの塩酸中に投入して攪拌しながら30分浸漬させ、その上澄液を除去した。このように塩酸中に浸漬して上澄液を除去する工程を繰り返して合計3回行った後、金属イオン吸着繊維を純水で洗浄した。
次に、金属イオン吸着繊維を2.5%濃度のKOH溶液中に投入し、KOH溶液約80℃まで加熱して60分浸漬した(80℃で60分間浸漬)後、金属イオン吸着繊維を取り出して純水で洗浄した。
そして、このように再生処理した金属イオン吸着繊維を再びカラムに詰めて試験2と同様の吸着試験を行い、これを4回繰り返して各繰り返し段階でのZn及びCdの破過曲線を図3に示した。
【0047】
この結果は、金属イオン吸着繊維の優れた耐久性を示しているばかりではなく、上記の如き再生処理を繰り返す程、金属イオン吸着繊維の金属吸着能力が高まることが判明した。この原因は明らかではないが、これより、未使用の金属イオン吸着繊維に対して上記の如き再生処理と同様の処理を施すことにより、金属イオン吸着繊維が本来備えている金属吸着能を最初から発揮させることができるものと考えられる。
【0048】
(試験4)
重金属含有土壌を塩酸に浸漬させて得られた上澄液(Zn濃度約150mg/L、Pb濃度約60mg/L)に水酸化ナトリウム溶液を添加してpH3〜7に調整した土壌溶出pH調整液と、
10%酢酸に水酸化ナトリウム溶液を添加してpH3〜7に調整し、調整した酢酸溶液にPb及びCdを各100mg/L添加した酢酸pH調整液と、
10g/Lクエン酸に水酸化ナトリウム溶液を添加してpH3〜7に調整し、調整した酢酸溶液にPb及びCdを各100mg/L添加したクエン酸pH調整液とを、試料溶液として用意した。
これらの試料溶液を用いて、試験1と同様にバッチ試験を行い、上澄液中のPb、Cd、Zn、Fe濃度を測定し、処理前後の重金属の濃度差から、金属イオン吸着繊維1g当たりの重金属の吸着量(mg)を算出し、図4、図5及び図6に示した。
【0049】
この結果、いずれの試料溶液においても、pH5以上で各金属の吸着量が増加し、特にZn並びにPb、Cd、Zn及びFeの吸着量はpH5〜7の間にピークが存在することが判明した。これより、重金属含有水のpHを約5〜7に調整することで、重金属の吸着量を高めることができることが分った。
【図面の簡単な説明】
【図1】実施例繊維を用いてカラム吸着試験(試験2)をした場合の流出液中のZn及びCd濃度を示した破過曲線である。
【図2】比較例繊維を用いてカラム吸着試験(試験2)をした場合の流出液中のZn及びCd濃度を示した破過曲線である。
【図3】金属イオン吸着繊維を繰り返し再生使用してカラム吸着試験(試験3)をした場合の流出液中のZn及びCd濃度を示した破過曲線である。
【図4】土壌溶出pH調整液のバッチ試験(試験4)において、pH3〜7に調整した場合の金属イオン吸着繊維1g当たりの重金属の吸着量(mg)を示した図である。
【図5】酢酸pH調整液のバッチ試験(試験4)において、pH3〜7に調整した場合の金属イオン吸着繊維1g当たりの重金属の吸着量(mg)を示した図である。
【図6】クエン酸pH調整液をバッチ試験(試験4)において、pH3〜7に調整した場合の金属イオン吸着繊維1g当たりの重金属の吸着量(mg)を示した図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a treatment method for effectively removing heavy metals from water and soil containing heavy metals such as Pb, Cd, and Zn, particularly from heavy metal-containing water from factories such as smelters.
[0002]
[Prior art]
Known methods for treating heavy metal ion-containing water include neutralization coagulation sedimentation, ion flotation, ion exchange, electrolytic flotation, electrodialysis, adsorption, reverse osmosis, and methods using metal collectors. Have been.
[0003]
The neutralization coagulation sedimentation method is a method of neutralizing heavy metal-containing water (water to be treated) using an alkaline agent, and converting heavy metal ions into hydroxides by adsorption and removal using zeolite, silica gel, or the like. In addition, a large amount of an alkali agent is required, and a large amount of metal hydroxide sludge is generated.
[0004]
In addition, the method using a metal collecting agent involves dissolving a metal collecting agent such as thiourea, oxine, diphenylcarbazide, thioglycolic acid, dimethylglyoxime, or guanidine sulfamate in water or the like to treat the target water to be treated. And the metal contained in the water to be treated is allowed to react with the metal-collecting agent to separate and remove the floc generated to collect the metal (see JP-A-2001-115137). However, there is a problem that a large amount of metal collecting agent is required and a large amount of floc is generated.
[0005]
Thus, the present invention provides a method for removing large amounts of sludge and floc, which can be easily performed in a relatively small facility, and has a high removal efficiency of heavy metals. Attention was paid to the method of directly removing heavy metals by adsorption.
[0006]
As a treatment method of this kind, for example, Patent Document 1 discloses that heavy metal ions in water to be treated are filtered using a porous membrane having a chelate group in a side chain until the ion concentration becomes 1/10 or less of the initial concentration. Disclosed is a heavy metal removal method characterized by treating.
[0007]
[0008]
Further,
[0009]
Further,
[0010]
[Patent Document 1]
JP-A-3-16601
[Patent Document 2]
JP-A-5-57280
[Patent Document 3]
JP-A-5-57281
[Patent Document 4]
JP-A-5-111885
[Patent Document 5]
JP 2000-176279 A
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide a treatment method for adsorbing and removing heavy metals in a liquid to be treated or a soil to be treated by using a chelating resin, which is more efficient and simple, and further enhances the adsorption capacity of Zn, Cd, and Pb. It is to provide a processing method that can be enhanced.
[0012]
[Problem solving means]
The present invention provides an adsorption step in which heavy metal-containing water is brought into contact with a metal ion-adsorbing fiber having an amidoxime group as a chelate functional group to adsorb heavy metal to the metal ion-adsorbing fiber, and the metal ion-adsorbing fiber having adsorbed the heavy metal is subjected to an acid solution. And a backwashing step of washing the metal ion-adsorbed fiber by contact with the heavy metal-containing fiber.
[0013]
According to such a processing method, sludge, floc, and the like are not generated during the processing, so that the processing procedure and facilities can be simplified and downsized, and the processing speed is high, so that the processing efficiency can be increased. Moreover, it is more suitable for treating a large amount of liquid than a conventional ion-exchange treatment of water using a chelate resin, and is particularly excellent as a method for treating heavy metal-containing water from a smelter. In particular, it is particularly excellent as a secondary treatment method after the heavy metal concentration is reduced to about 0.1 ppm to 100 ppm by a conventionally known treatment method.
In addition, it is also possible to independently carry out only the adsorption step of bringing heavy metal-containing water into contact with the metal ion-adsorbing fiber and adsorbing the heavy metal onto the metal ion-adsorbing fiber. Since the metal ion-adsorbed fiber having the heavy metal adsorbed thereon can be transported as it is, for example, in a place where it is difficult to construct a large-scale treatment facility such as a mountainous area, a treatment facility for performing only the adsorption step is provided. The metal ion-adsorbed fibers having adsorbed thereon can be transported to another treatment facility for subsequent treatment.
[0014]
In the above treatment method, when the heavy metal concentration in the liquid to be treated is high, a concentration step of concentrating heavy metals in the washing wastewater generated in the washing step, and neutralizing the heavy metal concentrate obtained in the concentration step It is preferable to add a neutralization step.
By such a concentration step, the amount of the neutralization treatment is reduced, whereby the amount of the neutralizing agent and the amount of the neutralized waste can be reduced.
[0015]
Further, in the method of treating the heavy metal-containing liquid, the pH of the heavy metal-containing water is measured before the adsorption step, and the pH of the heavy metal-containing water is adjusted to about 5 to 7 before being supplied to the adsorption step. Is preferred. The present inventor has found that metal ion-adsorbing fibers having an amidoxime group as a chelate functional group, in particular, metal ion-adsorbing fibers coexisting with a hydrophilic group near the amidoxime group, exhibit the best heavy metal adsorption capacity in the pH range of about 5 to 7. Has confirmed.
[0016]
The heavy metal-containing soil can be suitably treated by applying the above-mentioned method for treating heavy metal-containing water. That is, the heavy metal-containing soil is immersed in an acid solution having a pH of 5 to 7, and the supernatant is filtered as necessary to obtain heavy metal-containing water from the acid solution. In addition, heavy metal-containing soil can be treated efficiently as described above. Moreover, since the heavy metal-containing water can be most effectively adsorbed and removed when the pH of the heavy metal-containing water is about 5 to 7, the heavy metal-containing water is added to an acid solution having a pH of about 5 to 7, preferably an organic acid solution such as acetic acid or citric acid. The soil can be immersed, and in addition, it can then be fed to the adsorption process without pH adjustment, and still more effectively adsorb and remove heavy metals. Environmentally friendly reclaimed soil can also be obtained.
[0017]
In addition, "heavy metal" generally means gold (Au), platinum (Pt), silver (Ag), copper (Cu), mercury (Hg), tin (Sn), cadmium (Cd), lead (Pb), iron Metals having a specific gravity of 4 to 5 or more, such as (Fe) and zinc (Zn), are called heavy metals.
In the present invention, "heavy metal-containing water" includes all water containing heavy metals, for example, heavy metal-containing water, seawater, geothermal water from factories such as smelters, garbage incineration plants, research laboratories, hospitals, and the like. , Oil well water, general drainage and the like.
In the present invention, `` heavy metal-containing soil '' includes all soils containing heavy metals, for example, incineration ash generated in garbage incineration plants, treated sludge used in sewage treatment plants, etc. Include.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described.
[0019]
In the method for treating a heavy metal-containing liquid according to an example of the present invention, after the pH of the heavy metal-containing water is measured as necessary and the pH is adjusted to a predetermined range (pH adjustment step), the heavy metal-containing water is mixed with the metal ion-adsorbing fiber. To adsorb heavy metals to the metal ion-adsorbing fibers (adsorption step), and remove the adsorbed heavy metals from the metal ion-adsorbing fibers (backwashing step). It can be carried out through a step of concentrating heavy metals (concentration step) and, if necessary, neutralizing the concentrated heavy metal concentrate (neutralization step).
Hereinafter, this will be described in more detail.
[0020]
(Metal ion adsorption fiber)
The adsorbent used in the present invention is a metal ion-adsorbing fiber having an amidoxime group as a chelate functional group.
Such a metal ion-adsorbing fiber, for example, irradiates the base fiber with an electron beam to activate the movement of the fiber molecule to increase the reactivity (generate a radical as a reaction initiating species) and then polymerize the monomer. It can be obtained by a production method in which graft polymerization is performed, and hydroxylamine is reacted with the graft polymerization side chain to introduce an amidoxime group having a metal-capturing ability. However, it is not limited to this manufacturing method.
As the base fiber, a fiber made of polyethylene, polypropylene, polysulfone, polytetrafluoroethylene, or another polymer can be used. Among them, polyethylene and polypropylene are preferable because they can be easily subjected to graft polymerization. Examples of the radiation to be applied include α-rays, β-rays, γ-rays, X-rays, and accelerated electron beams. The irradiation dose is 100 to 200 kGy, and the atmosphere is in air or in an inert gas. The temperature is preferably set to 0 ° C.
As the polymerizable monomer, for example, any one of acrylonitrile, methacrylic acid, glycidyl methacrylate, acrylic acid, sodium styrenesulfonate, or a mixture of two or more of these can be used. Examples of the mixture include a mixture of acrylonitrile and methacrylic acid and a mixture of glycidyl methacrylate and acrylic acid. However, it is not limited to these.
[0021]
As the metal ion-adsorbing fibers used in the treatment of the present invention, among the above, metal ion-adsorbing fibers having an amidoxime group and a hydrophilic group in the same or different polymerization side chains are preferable.
Such a metal ion-adsorbing fiber is, for example, as described above, after irradiating the base fiber with an electron beam, graft polymerizing a polymerizable monomer having a hydrophilic group, and further polymerizing a monomer having a cyano group, or It can be obtained by a production method in which a monomer having a cyano group is graft-polymerized in the presence of a polymerizable monomer having a group. Specifically, it can be obtained by the methods disclosed in JP-A-2000-176279 and JP-A-2000-178531. That is, for example, the base fiber is irradiated with an electron beam, and in the presence of a polymerizable monomer having a hydrophilic group, a polymerizable monomer having a cyano group such as acrylonitrile is graft-polymerized to the base fiber, and in the graft polymerization side chain. It can be obtained by reacting a cyano group with hydroxylamine to convert the cyano group to an amidoxime group. Further, in the presence of a polymerizable monomer having a hydrophilic group, when graft polymerizing a polymerizable monomer having a cyano group such as acrylonitrile to the base fiber, the polymerizable monomer having a hydrophilic group and the polymerizable monomer having a cyano group After polymerization by adjusting the molar ratio, hydroxylamine (NH) was added to the cyano group in the graft polymerization side chain. 2 OH) to convert a cyano group into an amidoxime group.
At this time, as the polymerizable monomer having a cyano group, acrylonitrile, vinylidene cyanide, crotononitrile, methacrylonitrile, chloroacrylonitrile, 2-cyanomethyl acrylate, 2-cyanoethyl acrylate or a mixture thereof can be mentioned. Examples of the polymerizable monomer having a group include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, allyl alcohol, polyethylene glycol acrylate, polyethylene glycol methacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, N-vinylpyrrolidone, or acrylamide. Can be mentioned.
[0022]
In addition, instead of an amidoxime group as the chelating functional group of the metal ion-adsorbing fiber, it is easily estimated that an iminodiacetic acid group, a sulfonic acid group, a phosphoric acid group, a 2-pyrrolidone group, and the like are used, and the operation is the same. Can be easily estimated.
[0023]
The above metal ion-adsorbing fiber can be processed into a woven, non-woven, membrane, tubular, pleated, spiral, molding, or other shape and used in this treatment.
In order to increase the contact efficiency, it can be formed into a short fiber or a particle. It is also possible to use a woven or nonwoven metal ion-adsorbing fiber sheet in units of one sheet. However, as a laminate obtained by stacking a plurality of sheets, a laminate obtained by inserting a spacer between the fiber sheets and further stacking It is also possible to use as.
Furthermore, a cartridge filter that can be easily replaced can be formed and used.
[0024]
It is preferable that the metal ion-adsorbing fiber is pretreated in advance as follows to increase the heavy metal-adsorbing ability. By performing the pretreatment, the heavy metal adsorption ability originally provided in the metal ion-adsorbing fiber can be exhibited from the beginning.
[0025]
That is, after the unused metal ion-adsorbing fiber is brought into contact with the acid solution, the metal ion-adsorbing fiber is washed, and then the metal ion-adsorbing fiber is brought into contact with an aqueous solution of a metal hydroxide such as potassium hydroxide to perform a water washing treatment. Is preferred.
At this time, the steps of contacting with an acid solution, washing, contacting with a metal ion solution, and washing with water may be repeatedly performed.
[0026]
In the above pretreatment, the method of contacting with the acid solution is not particularly limited.For example, unused metal ion-adsorbed fibers may be put into an acid solution such as hydrochloric acid and sulfuric acid, and immersed for an appropriate time while stirring. preferable.
Washing of the metal ion-adsorbing fiber may be performed by, for example, putting the metal ion-adsorbing fiber into washing water such as pure water or ion-exchanged water and agitating the washing water or pouring the washing water, but is not limited to these methods. Not something.
The steps of contacting and washing with the acid solution may be repeated.
[0027]
In the pretreatment, the method of contacting with the metal ion solution is not particularly limited, but the metal ion-adsorbing fiber may be immersed in a metal ion solution such as a caustic potassium (KOH) solution. At this time, as the metal ion solution, it is preferable to use a solution containing ions of an alkali metal or alkaline earth metal such as K, Na, Ca, etc. Heating is preferred. By heating, the heavy metal adsorption ability of the unused metal ion-adsorbing fiber can be further increased, and the processing time can be shortened.
In the immersion in the metal ion solution, the metal ion-adsorbing fiber is put into the metal ion solution, immersed for an appropriate time while stirring, and then the supernatant is removed. This step may be performed repeatedly.
Subsequent water washing treatment may be performed by throwing into washing water such as pure water or ion-exchanged water and stirring, or flowing washing water. However, it is not limited to these methods.
[0028]
(PH adjustment step of heavy metal-containing water)
It is preferable to measure the pH of the heavy metal-containing water before supplying it to the adsorption step and adjust the pH to about 5 to 7.
A metal ion-adsorbing fiber having a normal chelate functional group does not exhibit chelating ability at a pH of about 7 or less. However, a metal ion-adsorbing fiber having an amidoxime group as a chelating functional group, in particular, a hydrophilic group coexisting near an amidoxime group. The resulting metal ion-adsorbing fiber can effectively adsorb and remove heavy metals even in the pH range of about 5 to 7.
Therefore, the pH of the heavy metal-containing water is measured, and if the pH is lower than about 5, an alkalizing agent such as sodium hydroxide or potassium hydroxide is added to adjust the pH to about 5 or more, while the pH is about 5 or more. If it is higher than 7, add an acid such as hydrochloric acid, sulfuric acid, nitric acid, citric acid, acetic acid, phosphoric acid, ascorbic acid, citric acid or a salt thereof (for example, sodium carbonate or sodium hydrogen sulfate) to a pH of about 7 or less. It is preferred to adjust to.
It should be noted that heavy metals can be effectively adsorbed and removed even if the pH is raised from about
In addition, since iron can be precipitated as hydroxide by adjusting the pH to about 3 or more, it is possible to remove iron in advance by inserting a solid-liquid separation step after the pH adjustment step, if necessary. In that case, the post-process can be performed without the influence of iron ions.
[0029]
(Adsorption process)
In the adsorption step, the heavy metal-containing water is brought into contact with the metal ion-adsorbing fiber, and the heavy metal is adsorbed on the metal ion-adsorbing fiber. Further, the treated water after contact with the metal ion-adsorbing fiber may be subjected to another treatment such as filtration as required, and then supplied to the intended use as heavy metal-removed water, or may be drained as it is.
[0030]
As a method of contacting the heavy metal-containing water with the metal ion-adsorbing fiber, for example, the heavy metal-containing water is passed through a column filled with the metal ion-adsorbing fiber, or the heavy metal-containing water is passed through a filter in which the metal ion-adsorbing fiber is laminated. Or by storing the heavy metal-containing water in the tank and agitating the tank with metal ion-adsorbing fibers to make contact with the metal ion-adsorbing fibers. If so, a suitable method can be adopted.
At this time, the packing density and amount of the metal ion-adsorbing fibers in the column or the filter, the flow rate of the heavy metal-containing water, and the like may be appropriately adjusted.
[0031]
(Backwash process)
The treated metal ion-adsorbed fiber that has absorbed the heavy metal is washed with a strong acid such as hydrochloric acid or sulfuric acid to remove the heavy metal from the metal ion-adsorbed fiber, thereby obtaining a regenerated metal ion-adsorbed fiber and a washed wastewater containing the heavy metal. .
[0032]
As the backwashing method, a conventionally known method can be adopted. However, preferably, the treated metal ion-adsorbed fibers having adsorbed heavy metals are immersed in a strong acid solution (eluent) such as hydrochloric acid or sulfuric acid, and the strong acid solution (pure water) is added. After washing the eluent, the metal ion-adsorbed fiber is immersed in a metal ion solution such as caustic potassium (KOH) solution and washed with water, and the washed wastewater containing heavy metals and the regenerated metal ion-adsorbed fiber are separated. You can get it.
In this case, the steps of immersion in the eluent and removal of the acid solution may be performed once, but are preferably repeated a plurality of times. Further, for example, the concentration of the eluent may be increased in order, and the acid may be contacted in multiple stages.
The type of the eluent is preferably selected as appropriate depending on the type of the metal to be recovered, the method of purifying the recovered metal, the ease of elution, the type of the functional group and the durability.
Also, as a metal ion solution. It is preferable to use a solution containing ions of an alkali metal or an alkaline earth metal such as K, Na, Ca, etc. In particular, a metal ion solution in which the metal ion-adsorbing fibers are immersed is about 70 to 80 ° C., preferably around 80 ° C. Heating is preferred. By heating, similarly to the unused metal ion-adsorbing fiber, the next heavy metal adsorption ability can be further enhanced, and the processing time can be shortened.
When the metal ion-adsorbing fiber is immersed in the metal ion solution and washed with water, preferably, the metal ion-adsorbing fiber is put into the metal ion solution, and the metal ion-adsorbing fiber is immersed for appropriate time with stirring, and then the supernatant is removed. This step is preferably repeated twice or more.
[0033]
(Concentration process)
The heavy metal-containing cleaning effluent obtained in the backwashing step is concentrated if necessary. Any known method may be used as the concentration method, and preferred examples thereof include a sedimentation concentration method and an electrodialysis method.
[0034]
(Neutralization step)
The heavy metal concentrate obtained in the above step is subjected to a neutralization treatment by adding an alkali metal hydroxide such as sodium hydroxide or sodium carbonate or a carbonate, if necessary.
By reacting with an alkali metal hydroxide, a carbonate, or the like, a poorly soluble compound is generated, and solid-liquid separation can be easily performed by filtration or the like. For example, a precipitate such as heavy metal carbonate can be obtained by neutralizing with lime or the like.
It is preferable that the treated water after neutralization has a weak alkalinity of
[0035]
(Recovery of heavy metals)
The heavy metal-containing cleaning effluent obtained in the backwashing step or the heavy metal-containing concentrated liquid neutralized in the above step is subjected to a solid-liquid separation treatment as necessary to recover heavy metals. However, even if the heavy metal is not collected, the treatment can be performed with the liquid containing the heavy metal at a high concentration.
[0036]
(Washing of soil containing heavy metals)
The heavy metal-containing soil is immersed in an acid to obtain a supernatant, and the supernatant is filtered and adjusted to
[0037]
In the treatment of the heavy metal-containing water or the heavy metal-containing soil, steps other than those described above may be inserted, or the order of the steps may be changed.
[0038]
(Test 1)
A heavy metal-containing water (Zn concentration: 110 mg / L, Cd concentration: 20 mg / L) from a smelter having a pH of about 7 was prepared as a sample solution, and a batch test was performed.
[0039]
As the metal ion-adsorbing fiber (Example fiber), a metal ion-adsorbing fiber in which an amidoxime group and a hydrophilic group coexist in the same graft polymerization side chain was prepared.
This metal ion-adsorbed fiber was irradiated with 200 kGy of a polyethylene nonwoven fabric using an electron accelerator under a nitrogen atmosphere, and then the irradiated fiber was subjected to nitrogen bubbling. MAA-AN graft fiber was immersed in a solution consisting of 3:10 and reacted at 40 ° C. for 5 hours to obtain MAA-AN graft fiber (graft conversion rate: 150%). % Hydroxylamine hydrochloride in water-methanol solution (water: methanol = 1: 1 weight ratio), and reacted at 80 ° C. for 1 hour.
[0040]
A commercially available chelate resin (MX-8C manufactured by Miyoshi Oil & Fat) was prepared as an adsorbent to be compared (referred to as “comparative adsorbent”).
[0041]
Three 0.05 cm (1 cm square) metal ion-adsorbing fibers (example fibers) were put into 50 mL of the sample solution, while 1.5 g of the comparative adsorbent was put into 500 mL of the sample solution, and stirred with a magnetic stirrer for 15 hours. The concentration of the supernatant was measured, and the amount of adsorption was calculated from the difference between the concentrations of heavy metals (Zn and Cd) before and after the treatment.
[0042]
As a result, the adsorption amount of Zn and Cd per 1 g of the adsorbent (Example fiber and Comparative adsorbent) was 80 mg for the Example fiber and 22 mg for the comparative adsorbent.
[0043]
(Test 2)
Heavy metal-containing water (Zn concentration 110 mg / L,
[0044]
The same example fiber as in Test 1 was chopped to about 0.3 g per piece, and 0.3 g of the chopped example fiber was packed into a glass column (about 2 ml in volume), and the sample solution was placed in this column with SV50 (100 ml). / Hr), the effluent was collected as 10 mL fractions, the Zn and Cd concentrations of each fraction were measured, and the breakthrough curves of each element were shown in FIG.
In addition, the same test (however, the flow rate was SV10 (20 ml / hr)) was performed on the above-mentioned comparative fiber, and the breakthrough curve is shown in FIG.
[0045]
As a result, the breakthrough curve was disturbed at the flow velocity of SV10 in the comparative example fiber, whereas the breakthrough curve was good at the flow velocity of SV50 in the example fiber.
[0046]
(Test 3)
In the same manner as in
Next, the metal ion-adsorbing fiber is put into a 2.5% KOH solution, heated to about 80 ° C. and soaked for 60 minutes (soaked at 80 ° C. for 60 minutes), and then the metal ion-adsorbing fiber is taken out. And washed with pure water.
Then, the metal ion-adsorbed fiber thus regenerated was packed in a column again, and the same adsorption test as in
[0047]
This result not only indicates the excellent durability of the metal ion-adsorbing fiber, but also reveals that the more the regenerating process as described above is repeated, the higher the metal adsorbing ability of the metal ion-adsorbing fiber is. Although the cause is not clear, from this, the metal adsorption ability originally provided by the metal ion-adsorbing fiber is initially performed by performing the same treatment as the above-described regeneration treatment on the unused metal ion-adsorbing fiber. It is thought that it can be demonstrated.
[0048]
(Test 4)
Sodium hydroxide solution was added to a supernatant (Zn concentration: about 150 mg / L, Pb concentration: about 60 mg / L) obtained by immersing heavy metal-containing soil in hydrochloric acid to adjust the pH to 3 to 7 and the pH was adjusted to pH. When,
A 10% acetic acid solution was added to a sodium hydroxide solution to adjust the pH to 3 to 7, and the adjusted acetic acid solution was added with 100 mg / L of Pb and Cd to each acetic acid pH adjusting solution.
A sodium hydroxide solution was added to 10 g / L citric acid to adjust the pH to 3 to 7, and a pH adjusted solution of citric acid in which 100 mg / L of Pb and Cd was added to the adjusted acetic acid solution was prepared as a sample solution.
Using these sample solutions, a batch test was performed in the same manner as in Test 1, and the concentrations of Pb, Cd, Zn, and Fe in the supernatant were measured. , And the adsorption amount (mg) of the heavy metal was calculated and shown in FIGS. 4, 5 and 6.
[0049]
As a result, in any of the sample solutions, the adsorption amount of each metal increased at
[Brief description of the drawings]
FIG. 1 is a breakthrough curve showing the Zn and Cd concentrations in the effluent when a column adsorption test (Test 2) was performed using the fibers of Example.
FIG. 2 is a breakthrough curve showing Zn and Cd concentrations in an effluent when a column adsorption test (test 2) was performed using fibers of a comparative example.
FIG. 3 is a breakthrough curve showing Zn and Cd concentrations in an effluent when a column adsorption test (test 3) is performed by repeatedly regenerating and using metal ion-adsorbed fibers.
FIG. 4 is a graph showing the amount (mg) of heavy metal adsorbed per 1 g of metal ion-adsorbed fiber when the pH is adjusted to 3 to 7 in a batch test (test 4) of a soil elution pH adjusting solution.
FIG. 5 is a diagram showing the adsorption amount (mg) of heavy metal per 1 g of metal ion-adsorbing fiber when adjusted to
FIG. 6 is a graph showing the amount (mg) of heavy metal adsorbed per gram of metal ion-adsorbed fiber when a pH adjustment solution of citric acid was adjusted to
Claims (3)
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JP2006255515A (en) * | 2005-03-15 | 2006-09-28 | Nippo Corporation:Kk | Method for decontaminating soil contaminated with heavy metal |
KR101457096B1 (en) * | 2013-04-22 | 2014-10-31 | (주)제이엔티아이엔씨 | Eco-friendly deep soil mixing method using heavy metal absorbents and air bubbling |
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JP2006255515A (en) * | 2005-03-15 | 2006-09-28 | Nippo Corporation:Kk | Method for decontaminating soil contaminated with heavy metal |
KR101457096B1 (en) * | 2013-04-22 | 2014-10-31 | (주)제이엔티아이엔씨 | Eco-friendly deep soil mixing method using heavy metal absorbents and air bubbling |
CN104874601A (en) * | 2015-06-03 | 2015-09-02 | 天津工业大学 | Competitive-adsorption-based in-situ quick restoration method for cadmium-polluted paddy field |
KR101663469B1 (en) * | 2016-02-22 | 2016-10-07 | 한국조명재활용공사 주식회사 | Method for removing mercury using automatic disposal system of mercury-containing waste |
CN105936824A (en) * | 2016-04-06 | 2016-09-14 | 深圳多元拓展环保科技有限公司 | Soil heavy metal activator and preparation method and application thereof |
JP2021070859A (en) * | 2019-11-01 | 2021-05-06 | オルガノ株式会社 | Metal recovery method and metal recovery device |
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