JP2018099636A - Adsorbent for detoxification treatment of contaminant - Google Patents
Adsorbent for detoxification treatment of contaminant Download PDFInfo
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Abstract
Description
本発明は、汚染物質の無害化処理用吸着剤、具体的には、汚染土壌等の汚染物質の原因物質である重金属を高い回収率にて回収可能とする汚染物質の無害化処理用吸着剤に関する。 The present invention relates to an adsorbent for the detoxification treatment of pollutants, specifically, an adsorbent for the detoxification treatment of pollutants that makes it possible to recover heavy metals that are causative substances of pollutants such as contaminated soil at a high recovery rate. About.
近年、自然由来および又は産業活動に起因した有害物質である重金属による土壌汚染・水質汚染が顕在化している。このため、これらの汚染に対する環境保全が重要な社会的課題であるといえる。自然由来の重金属による土壌・地下水汚染については、従来、土壌汚染対策法の規制対象外であったが、２０１０年４月に土壌汚染対策法が改正され、現在では、たとえ自然由来の重金属であっても、場合によっては、その拡散を防ぐ必要がある。
このうち、代表的な汚染物質であるヒ素は、国内の天然土壌に多く分布している。このため、都市再開発やトンネル工事などで発生した掘削土に高濃度のヒ素が含まれる場合がよくあり、簡単にヒ素を除去することが社会的に要求されている。
また、海外においても、インドやバングラデシュなどの開発途上国を中心とする各国でヒ素等を含む汚染地下水の飲用による地域住民の健康被害が深刻であり、社会資本整備による恒久的な浄化対策が必要となっている。
このような状況のもと、近年では、特許文献１や非特許文献１に示すように、鉄粉にヒ素を吸着させることによって、汚染土壌からヒ素を除去する技術が注目されている。
In recent years, soil contamination and water pollution due to heavy metals, which are harmful substances derived from nature and / or industrial activities, have become apparent. For this reason, it can be said that environmental protection against these pollutions is an important social issue. Conventionally, soil and groundwater contamination by naturally occurring heavy metals was outside the scope of the Soil Contamination Countermeasures Law, but the Soil Contamination Countermeasures Law was amended in April 2010, and now it is a natural heavy metal. However, in some cases, it is necessary to prevent the diffusion.
Of these, arsenic, which is a typical pollutant, is widely distributed in domestic natural soil. For this reason, excavated soil generated in urban redevelopment or tunnel construction often contains high concentrations of arsenic, and it is socially required to remove arsenic easily.
Overseas, the health hazards of local residents due to drinking of contaminated groundwater containing arsenic are serious in developing countries such as India and Bangladesh, and permanent purification measures are needed through social capital development. It has become.
Under such circumstances, in recent years, as shown in
しかしながら、特許文献１、非特許文献１によれば、ヒ素の吸着率は、鉄粉製品を多量に投入しなければ、ヒ素の検出限界を超えることができなかった。また、ヒ素以外の重金属、特に、六価クロムと鉛については、吸着率が低く、社会的要求に十分に応えることができなかった。
However, according to
本発明は、高い回収率にて汚染土壌から重金属を回収するものである。そして、鉄成分だけでなく、重金属の化学特性に着目し、鉄粉にアルカリ金属またはアルカリ土類金属の酸化物を付着させ、この酸化物と重金属とを反応させることにより、高い吸着率にて汚染物質から重金属を吸着させることができることを知見した。また、アルカリ金属またはアルカリ土類金属の酸化物を鉄粉に付着させることで、吸着した重金属を容易に分離可能とすることができることを知見した。これらの知見から、本発明を完成させた。 The present invention recovers heavy metals from contaminated soil at a high recovery rate. Focusing on the chemical properties of heavy metals as well as iron components, by attaching oxides of alkali metals or alkaline earth metals to iron powder and reacting these oxides with heavy metals, the adsorption rate is high. It was found that heavy metals can be adsorbed from pollutants. It was also found that the adsorbed heavy metal can be easily separated by attaching an oxide of an alkali metal or alkaline earth metal to the iron powder. Based on these findings, the present invention has been completed.
本発明は、汚染土壌等の汚染物質の原因物質である重金属を吸着するとともに、その吸着した重金属を機械的衝撃により分離可能とすることにより、汚染物質の無害化処理を容易にすることを目的とする。 It is an object of the present invention to facilitate the detoxification treatment of pollutants by adsorbing heavy metals that are causative substances of pollutants such as contaminated soil and making the adsorbed heavy metals separable by mechanical impact. And
請求項１に記載の発明は、汚染物質中に含まれる重金属を吸着するとともに、その吸着した重金属を分離可能とする汚染物質の無害化処理用吸着剤であって、鉄粉の表面に形成された酸化鉄の酸化膜の一部に、アルカリ金属又はアルカリ土類金属の酸化物である金属酸化物が付着した、塩基性の汚染物質の無害化処理用吸着剤である。
The invention described in
本発明に係る汚染物質に含まれる重金属とは、人体に対して有害と認められる物質のうち、鉄やアルカリ金属、アルカリ土類金属に対し反応性が認められるものをいい、ヒ素、六価クロム、カドミウム、鉛等である。汚染物質とは、これらの重金属が混在した物質であり、汚染土壌や汚染水等が挙げられる。
アルカリ金属は１価の陽イオンになりやすい金属であり、代表的なものとして、カリウム、ナトリウムが挙げられる。アルカリ土類金属は、２価の陽イオンになりやすい金属であり、代表的なものとしてマグネシウム、カルシウムが挙げられる。
本発明に係る汚染物質の無害化処理用吸着剤は、鉄粉の表面に酸化膜、つまり、酸化鉄の膜で覆われ、その表面の一部に金属酸化物が付着したものである。つまり、酸化鉄の膜の表面の一部に金属酸化物が付着し、それ以外の部分は酸化鉄の膜が露出している。
なお、酸化鉄の酸化膜は、鉄粉の表面全面に形成されていても鉄粉の表面の一部に形成されていてもよい。
The heavy metal contained in the pollutant according to the present invention refers to a substance recognized to be harmful to the human body and reactive to iron, alkali metal, and alkaline earth metal. Arsenic, hexavalent chromium , Cadmium, lead and the like. A pollutant is a substance in which these heavy metals are mixed, and includes contaminated soil and contaminated water.
Alkali metal is a metal that easily becomes a monovalent cation, and typical examples include potassium and sodium. Alkaline earth metal is a metal that tends to be a divalent cation, and typical examples include magnesium and calcium.
The adsorbent for detoxification treatment of contaminants according to the present invention is one in which the surface of iron powder is covered with an oxide film, that is, an iron oxide film, and a metal oxide adheres to a part of the surface. That is, the metal oxide adheres to a part of the surface of the iron oxide film, and the iron oxide film is exposed in the other parts.
The iron oxide oxide film may be formed on the entire surface of the iron powder or may be formed on a part of the surface of the iron powder.
本発明に係る汚染物質の無害化処理用吸着剤の効果が得られる科学的根拠は明確ではない。しかしながら、後述する実施例に示すデータから次のように推察することができる。
アルカリ金属、アルカリ土類金属の酸化物に含まれる金属イオン及び鉄粉、酸化鉄中に含まれる鉄イオンが水分子の存在により溶出し、ヒ素等の重金属と結合して錯体を構成する。この錯体は塩基性雰囲気においては水に対し不溶性である。この錯イオンは全体として正の電荷を帯びる。一方、金属イオンが放出された後の汚染土壌の無害化処理用吸着剤全体には負の電荷を帯び、錯イオンの吸着固定化を促進する。このようにして、汚染物質中の重金属が汚染物質の無害化処理用吸着剤に吸着されるものと考えられる。
アルカリ金属、アルカリ土類金属の酸化物が付着していることから、本発明に係る汚染物質の無害化処理用吸着剤は、純水に投入した際、塩基性を示す。本来であれば、重金属の吸着は中性領域において高い吸着性能を示すが、本発明に係る汚染物質の無害化処理用吸着剤は、ｐＨが１２以上である強塩基性領域であっても、ヒ素等の吸着力が高く（つまり、回収効率が高い）、有効であるといえる。
The scientific basis for obtaining the effect of the adsorbent for detoxifying a pollutant according to the present invention is not clear. However, it can be inferred from the data shown in the examples described later as follows.
Metal ions contained in oxides of alkali metals and alkaline earth metals and iron ions contained in iron powder and iron oxide are eluted by the presence of water molecules, and are combined with heavy metals such as arsenic to form a complex. This complex is insoluble in water in a basic atmosphere. This complex ion has a positive charge as a whole. On the other hand, the entire adsorbent for detoxification treatment of the contaminated soil after the metal ions are released has a negative charge, facilitating the adsorption and fixation of complex ions. In this way, it is considered that the heavy metal in the pollutant is adsorbed by the adsorbent for the detoxification treatment of the pollutant.
Since the oxides of alkali metals and alkaline earth metals are attached, the adsorbent for detoxifying contaminants according to the present invention exhibits basicity when introduced into pure water. Originally, heavy metal adsorption exhibits high adsorption performance in a neutral region, but the contaminant-detoxifying treatment adsorbent according to the present invention is a strongly basic region having a pH of 12 or more. It can be said that the adsorption power of arsenic or the like is high (that is, the recovery efficiency is high) and effective.
また、金属酸化物は酸化鉄の酸化膜を介して鉄粉に付着している。付着の形態は特に問わないが、金属酸化物が酸化鉄の酸化膜に付着することで、金属酸化物と鉄粉とが容易に分離することが可能である。
さらに、本発明に係る汚染物質の無害化処理用吸着剤の中心（コア、核）となる部分は鉄である。このため、汚染物質に本発明に係る汚染物質の無害化処理用吸着剤を混合（投入）し、重金属を吸着した後に、重金属が吸着した汚染物質の無害化処理用吸着剤を取り出すために磁力選別をすればよく、極めて簡単に汚染物質の無害化処理用吸着剤を取り出すことができる。その後、吸着した重金属を化学的又は物理的処理により汚染物質の無害化処理用吸着剤を分離すれば、重金属に対して適切な処理を行うことができる。また、重金属を分離した使用済みの汚染物質の無害化処理用吸着剤については、再び汚染物質の無害化処理用吸着剤として利用することができる（つまり、再利用が可能である）。ここで物理的衝撃を与える処理とは、破砕機による破砕、摩鉱を含むものとする。
Further, the metal oxide is attached to the iron powder through an oxide film of iron oxide. The form of attachment is not particularly limited, but the metal oxide can be easily separated from the iron powder by attaching the metal oxide to the iron oxide film.
Furthermore, the part which becomes the center (core, core) of the adsorbent for the detoxification treatment of the contaminant according to the present invention is iron. For this reason, the adsorbent for the detoxification treatment of the pollutant according to the present invention is mixed (injected) into the pollutant, and after adsorbing the heavy metal, the magnetic The adsorbent for the detoxification treatment of the pollutant can be taken out very easily. Thereafter, if the adsorbent for detoxifying contaminants is separated from the adsorbed heavy metal by chemical or physical treatment, an appropriate treatment can be performed on the heavy metal. In addition, the used adsorbent for detoxification of used pollutants from which heavy metals have been separated can be used again as an adsorbent for detoxification of pollutants (that is, it can be reused). Here, the process of giving a physical impact includes crushing by a crusher and grinding.
請求項２に記載の発明は、前記金属酸化物は、酸化カルシウムである請求項１に記載の汚染物質の無害化処理用吸着剤である。
The invention described in claim 2 is the adsorbent for detoxification treatment of pollutants according to
請求項３に記載の発明は、前記汚染物質の無害化処理用吸着剤が製鋼スラグから得られた請求項１又は請求項２に記載の汚染物質の無害化処理用吸着剤である。
The invention described in claim 3 is the adsorbent for detoxification treatment of pollutants according to
請求項３に記載の発明に係る汚染物質の無害化処理用吸着剤は、表面に酸化膜が形成された鉄粉の表面の一部に、酸化カルシウムが付着したもの、すなわち、鉄鋼スラグをベースに製造することが可能なものである。鉄鋼スラグのうち、製鋼スラグについて、磁力選別と篩い分けを繰り返すことにより、表面に酸化膜が形成された鉄粉の表面の一部に、酸化カルシウムが付着した汚染物質の無害化処理用吸着剤を得ることができる。すなわち、請求項３に記載の発明は、汚染物質の無害化処理用吸着剤の製造が容易であることから、低コストでかつ容易に汚染物質の無害化処理を行うことができる。 The adsorbent for detoxification treatment of pollutants according to the invention of claim 3 is based on the iron powder having an oxide film formed on the surface thereof, to which calcium oxide is adhered, that is, based on steel slag. It can be manufactured. Among steel slags, the adsorbent for detoxification treatment of pollutants with calcium oxide adhering to a part of the surface of the iron powder with oxide film formed on the surface by repeating the magnetic separation and sieving of steel slag Can be obtained. That is, according to the third aspect of the invention, since the adsorbent for the detoxification treatment of the pollutant is easy, the detoxification treatment of the pollutant can be easily performed at a low cost.
請求項４に記載の発明は、吸着した重金属を物理的衝撃により分離可能とする請求項１〜請求項３のうちいずれか１項に記載の汚染物質の無害化処理用吸着剤である。
吸着後の汚染物質の無害化処理用吸着剤に物理的衝撃を加えることにより重金属を分離可能とすることができることから、汚染物質から重金属を回収するコストや、分離された重金属を処分するコストをさらに抑えることができる。
The invention described in claim 4 is the adsorbent for detoxifying a pollutant according to any one of
Since it is possible to separate heavy metals by applying a physical impact to the adsorbent for detoxification treatment of pollutants after adsorption, the cost of recovering heavy metals from pollutants and the cost of disposing of separated heavy metals can be reduced. It can be further suppressed.
本発明によれば、アルカリ金属、アルカリ土類金属の酸化物に含まれる金属イオン及び鉄粉、酸化鉄中に含まれる鉄イオンが水分子の存在により溶出し、ヒ素等の重金属と結合して正の電荷を帯びた錯体を構成する一方、金属イオンが放出された後の汚染物質の無害化処理用吸着剤全体には負の電荷を帯び、錯イオンの吸着固定化を促進する。このため、本来であれば、重金属の吸着は中性領域において高い吸着性能を示すが、本発明に係る汚染物質の無害化処理用吸着剤は、ｐＨが１２以上である強塩基性領域であっても、ヒ素等の吸着力が高く（つまり、回収効率が高い）、有用であるといえる。
また、金属酸化物は酸化鉄の酸化膜を介して鉄粉に付着している。付着の形態は特に問わないが、金属酸化物が酸化鉄の酸化膜に付着することで、金属酸化物と鉄粉とが容易に分離することが可能である。
さらに、本発明に係る汚染物質の無害化処理用吸着剤の中心（コア、核）となる部分は鉄である。このため、汚染物質に本発明に係る汚染物質の無害化処理用吸着剤を混合（投入）し、重金属を吸着した後に、重金属が吸着した汚染物質の無害化処理用吸着剤を取り出すために磁力選別をすればよく、極めて簡単に汚染物質の無害化処理用吸着剤を取り出すことができる。その後、吸着した重金属を化学的又は物理的処理により汚染物質の無害化処理用吸着剤を分離すれば、重金属に対して適切な処理を行うことができる。また、重金属を分離した使用済みの汚染物質の無害化処理用吸着剤については、再び汚染物質の無害化処理用吸着剤として利用することができる（つまり、再利用が可能である）。
According to the present invention, metal ions and iron powder contained in oxides of alkali metals and alkaline earth metals and iron ions contained in iron oxide are eluted due to the presence of water molecules, and bind to heavy metals such as arsenic. While forming a positively charged complex, the entire adsorbent for detoxifying the pollutant after the release of metal ions is negatively charged, facilitating the adsorption and fixation of complex ions. Therefore, originally, heavy metal adsorption exhibits high adsorption performance in the neutral region, but the contaminant-detoxifying adsorbent according to the present invention is a strongly basic region having a pH of 12 or more. However, it can be said that the adsorption power of arsenic or the like is high (that is, the recovery efficiency is high) and it is useful.
Further, the metal oxide is attached to the iron powder through an oxide film of iron oxide. The form of attachment is not particularly limited, but the metal oxide can be easily separated from the iron powder by attaching the metal oxide to the iron oxide film.
Furthermore, the part which becomes the center (core, core) of the adsorbent for the detoxification treatment of the contaminant according to the present invention is iron. For this reason, the adsorbent for the detoxification treatment of the pollutant according to the present invention is mixed (injected) into the pollutant, and after adsorbing the heavy metal, the magnetic The adsorbent for the detoxification treatment of the pollutant can be taken out very easily. Thereafter, if the adsorbent for detoxifying contaminants is separated from the adsorbed heavy metal by chemical or physical treatment, an appropriate treatment can be performed on the heavy metal. In addition, the used adsorbent for detoxification of used pollutants from which heavy metals have been separated can be used again as an adsorbent for detoxification of pollutants (that is, it can be reused).
請求項２に記載の発明に係る汚染物質の無害化処理用吸着剤は、鉄鋼スラグをベースに製造することが可能なものであり、低コストで汚染物質の無害化処理用吸着剤を製造することができる。特に、請求項３に記載の発明では、鉄鋼スラグのうち、製鋼スラグについて、磁力選別と篩い分けを繰り返すことにより、表面に酸化膜が形成された鉄粉の表面の一部に、酸化カルシウムが付着した汚染物質の無害化処理用吸着剤を得ることができ、それを使用すれば低コストでかつ容易に汚染物質の無害化処理を行うことができる。 The adsorbent for detoxification treatment of pollutants according to the invention of claim 2 can be produced based on steel slag, and produces the adsorbent for detoxification treatment of pollutants at low cost. be able to. In particular, in the invention according to claim 3, calcium oxide is formed on a part of the surface of the iron powder having an oxide film formed on the surface thereof by repeating the magnetic separation and sieving of the steel slag out of the steel slag. An adsorbent for detoxification treatment of adhering contaminants can be obtained, and if it is used, it can be easily detoxified at low cost.
また、請求項４に記載の発明によれば、吸着後の汚染物質の無害化処理用吸着剤に物理的衝撃を加えることにより重金属を分離可能とすることができることから、汚染物質から重金属を回収するコストをさらに抑えることができる。 In addition, according to the invention described in claim 4, heavy metal can be separated by applying a physical impact to the adsorbent for detoxification treatment of the pollutant after adsorption, so that heavy metal is recovered from the pollutant. Cost can be further reduced.
本発明の実施例に係る汚染物質（汚染土壌）の無害化処理用吸着剤（以下、単に「吸着剤」と記載する。）の、ＳＥＭ写真を図１に示す。図１のａで示されるもの（ａ地点を含む全体）の成分について図２（ａ）のＥＤＸチャートにて分析すると、Ｆｅを示すピークが高く、Ｏを示すピークは低く表れている。つまり、図１のａで示される部分は鉄（酸化されていない鉄）である。そして、図１のａで示される部分の縦横の最長の長さ（距離）はおおよそ０．２ｍｍである。すなわち、本実施例に係る吸着剤は、粒径おおよそ０．２ｍｍの粒状の鉄粉が存在する。
図１のｂで示されるもの（ｂ地点を含む全体）の成分について図２（ｂ）のＥＤＸチャートにて分析すると、Ｆｅを示すピークとＯを示すピークが高く表れている。つまり、図１のｂで示される部分は酸化鉄である。そして、図１のｂで示される部分の幅はおおよそ１０μｍである。すなわち、本実施例に係る吸着剤は、粒径おおよそ０．２ｍｍの粒状の鉄粉の表面に厚さ１０μｍ程度の酸化鉄（酸化膜）が存在する。
図１のｃで示されるもの（ｃ地点を含む全体）の成分について図２（ｃ）のＥＤＸチャートにて分析すると、Ｃａを示すピークとＯを示すピークが高く表れている。また、Ｍｇを示すピーク、Ｓｉ、Ａｌを示すピークも高く表れている。つまり、図１のｃで示される部分は主に酸化カルシウムであるが、シリカ（二酸化ケイ素）、アルミナ（酸化アルミニウム）、酸化マグネシウムも含まれている。そして、図１のｃで示される部分は、図１のｂに示す部分の表面全体を覆うように存在しておらず、図１のｂに示す部分の表面の一部に付着しているように存在している。
以上のとおり、図１、図２に示すように、本発明の実施例に係る吸着剤は、表面に酸化膜が形成された鉄粉の表面の一部に、酸化カルシウムが付着している。
この吸着剤は製鋼スラグから磁力選別、ふるい選別を組み合わせて製造されるものである。そして、前述の通り、酸化カルシウムが多く含まれている。つまり、この吸着剤は、塩基性スラグである。
An SEM photograph of an adsorbent for detoxification treatment of a pollutant (contaminated soil) according to an example of the present invention (hereinafter simply referred to as “adsorbent”) is shown in FIG. When the components shown by a in FIG. 1 (the whole including the point a) are analyzed by the EDX chart in FIG. 2A, the peak indicating Fe is high and the peak indicating O is low. That is, the portion indicated by a in FIG. 1 is iron (unoxidized iron). And the longest length (distance) of the part shown by a of FIG. 1 is about 0.2 mm. That is, the adsorbent according to the present embodiment includes granular iron powder having a particle size of approximately 0.2 mm.
When the components shown by b in FIG. 1 (the whole including the point b) are analyzed by the EDX chart in FIG. 2B, the peak indicating Fe and the peak indicating O appear high. That is, the portion indicated by b in FIG. 1 is iron oxide. And the width of the part shown by b of FIG. 1 is about 10 micrometers. That is, the adsorbent according to the present example has iron oxide (oxide film) having a thickness of about 10 μm on the surface of granular iron powder having a particle size of about 0.2 mm.
When the components shown by c in FIG. 1 (the whole including the point c) are analyzed by the EDX chart in FIG. 2C, the peak indicating Ca and the peak indicating O are high. Moreover, the peak which shows Mg and the peak which shows Si and Al are also appearing high. That is, the part shown by c in FIG. 1 is mainly calcium oxide, but also includes silica (silicon dioxide), alumina (aluminum oxide), and magnesium oxide. And the part shown by c of FIG. 1 does not exist so that the whole surface of the part shown to b of FIG. 1 may be covered, but it has adhered to a part of surface of the part shown by b of FIG. Exists.
As described above, as shown in FIGS. 1 and 2, in the adsorbent according to the embodiment of the present invention, calcium oxide is attached to a part of the surface of the iron powder having an oxide film formed on the surface.
This adsorbent is produced from steelmaking slag by combining magnetic force sorting and sieve sorting. And as above-mentioned, many calcium oxides are contained. That is, this adsorbent is basic slag.
この吸着剤は、篩い分け、破砕分離、篩い分け、磁力選別を組み合わせて製造される。具体的には、図３に示すように、原料となる製鋼スラグを目開き２５ｍｍの振動篩により篩い分けする。目開き２５ｍｍの振動篩に残った残留物（つまり、粒径２５ｍｍ以上の原料）をロッドミルにて粉砕する。その後、所定の粒径まで篩い分けをした後に、磁力選別機により、１回目の磁力選別を行う。このときの磁束密度は０．１５テスラである。
１回目の磁力選別による磁着物についてセパレータにて所定の粒径を超えるものと、それ以外のもの（所定の粒径以下のもの）とにセパレートした後、所定の粒径以下のものについて２回目の磁力選別を行う。また、所定の粒径を超えるものについては、原料投射型の破砕機にて破砕した後、多重篩にて所定の目開きを通過するものについても、２回目の磁力選別により磁力選別する。このときの磁束密度は０．１５テスラである。この磁力選別による磁着物を吸着剤として使用する。
This adsorbent is produced by combining sieving, crushing separation, sieving, and magnetic separation. Specifically, as shown in FIG. 3, steelmaking slag as a raw material is sieved with a vibrating sieve having a mesh opening of 25 mm. The residue (that is, the raw material having a particle size of 25 mm or more) remaining on the vibrating sieve having a mesh opening of 25 mm is pulverized by a rod mill. Then, after sieving to a predetermined particle size, the first magnetic separation is performed by a magnetic separator. The magnetic flux density at this time is 0.15 Tesla.
The magnetic deposits obtained by the first magnetic separation are separated into those exceeding the predetermined particle size by the separator and those other than the predetermined particle size (those having a predetermined particle size or less), and the second time for those having the predetermined particle size or less. Perform magnetic sorting. In addition, those that exceed a predetermined particle size are crushed by a raw material projection type crusher, and then those that pass through a predetermined opening by a multiple sieve are also magnetically sorted by the second magnetic sorting. The magnetic flux density at this time is 0.15 Tesla. The magnetized material obtained by this magnetic sorting is used as an adsorbent.
（吸着性能試験）
本発明にかかる汚染物質（汚染土壌）の無害化処理用吸着剤について、ヒ素、カドミウム、六価クロムおよび鉛の吸着性能を測定した。
本発明にかかる汚染土壌の無害化処理用吸着剤の成分を表１に示す。
このうち、Ｔ．Ｆｅは吸着剤に含まれる鉄の総量であり、Ｍ．Ｆｅは酸化されていない鉄の量を示す。また、比較サンプル２は、汚染土壌の吸着剤として一般的に販売されている従来品（鉄粉）である。
(Adsorption performance test)
With respect to the adsorbent for detoxifying the pollutant (contaminated soil) according to the present invention, the adsorption performance of arsenic, cadmium, hexavalent chromium and lead was measured.
Table 1 shows the components of the adsorbent for detoxification treatment of contaminated soil according to the present invention.
Of these, T.W. Fe is the total amount of iron contained in the adsorbent. Fe indicates the amount of iron that has not been oxidized. Comparative sample 2 is a conventional product (iron powder) generally sold as an adsorbent for contaminated soil.
（ヒ素の吸着性能試験）
水中にヒ素を１０ｐｐｍ添加・溶解したヒ素水溶液を２５０ｍｌ用意し、これに吸着剤を添加した内容積５００ｍｌのバイアル瓶を密封し、２５℃の恒温水槽に浸漬して、７２時間振とうした。その後、メンブランフィルタでろ別し、ろ液中のヒ素の濃度を定量して、吸着除去率を求めた。ヒ素の濃度は、ＩＣＰ発光分光分析法（高周波誘導結合プラズマ発光分光分析法、サーモフィッシャーサイエンティフィック社製、型式：ｉＣＡＰ６３００ＤＵＯ）にて分析した。また、ヒ素吸着初期時における水溶液のｐＨを測定した。ヒ素の吸着性能試験の試験結果を表２に示す。
(Arsenic adsorption performance test)
250 ml of an arsenic aqueous solution in which 10 ppm of arsenic was added / dissolved in water was prepared, and a 500 ml vial with an adsorbent added thereto was sealed, immersed in a constant temperature water bath at 25 ° C., and shaken for 72 hours. Then, it filtered with the membrane filter, the density | concentration of the arsenic in a filtrate was quantified, and the adsorption removal rate was calculated | required. The arsenic concentration was analyzed by ICP emission spectroscopy (high frequency inductively coupled plasma emission spectroscopy, manufactured by Thermo Fisher Scientific, model: iCAP6300DUO). Further, the pH of the aqueous solution at the initial stage of arsenic adsorption was measured. The test results of the arsenic adsorption performance test are shown in Table 2.
（カドミウム、六価クロム、鉛の吸着性能試験）
カドミウム、六価クロム、鉛についてヒ素吸着性能試験と同様の試験を行った。その結果を表３に示す。
(Adsorption performance test of cadmium, hexavalent chromium and lead)
Tests similar to the arsenic adsorption performance test were performed on cadmium, hexavalent chromium, and lead. The results are shown in Table 3.
以上の結果から、本発明に係る汚染物質の無害化処理用吸着剤については、ヒ素の吸着が９９％以上と極めて高いだけでなく、カドミウム、六価クロム、鉛の吸着においても高い吸着が可能であることが明らかとなった。 From the above results, the adsorbent for detoxifying pollutants according to the present invention is not only highly adsorbed with arsenic of 99% or more, but also highly adsorbed with cadmium, hexavalent chromium and lead. It became clear that.
本発明に係る汚染物質の無害化処理用吸着剤の効果が得られる科学的根拠は明確ではないものの、吸着初期時のｐＨに着目すると、本来であれば、重金属の吸着は中性領域において高い吸着性能を示し、強酸性領域及び強塩基性領域においては低い吸着性能を示すが、本発明に係る汚染物質の無害化処理用吸着剤にあっては、ｐＨが１２以上と強塩基性領域であるにもかかわらず、重金属の吸着率が高い。
アルカリ金属、アルカリ土類金属の酸化物に含まれる金属イオン及び鉄粉、酸化鉄中に含まれる鉄イオンが水分子の存在により溶出し、ヒ素等の重金属と結合して錯体を構成する。この錯体は塩基雰囲気においては水に対し不溶性である。この錯イオンは全体として正の電荷を帯びる。一方、金属イオンが放出された後の汚染土壌の無害化処理用吸着剤全体には負の電荷を帯び、錯イオンの吸着固定化を促進する。このようにして、汚染物質中の重金属が汚染物質の無害化処理用吸着剤に吸着されるものと考えられる。
このため、ｐＨの高い強塩基性領域においても重金属の吸着率を高めるためには、汚染物質の無害化処理用吸着剤を純水に投入した際に塩基性を示すことが必要であり、酸化膜が形成された鉄粉の表面の一部に付着している金属酸化物は、アルカリ金属、アルカリ土類金属の酸化物であればよいといえる。
Although the scientific basis for obtaining the effect of the adsorbent for detoxifying the pollutant according to the present invention is not clear, when focusing on the pH at the initial stage of adsorption, the adsorption of heavy metals is originally high in the neutral region In the strongly acidic region and the strongly basic region, the adsorption performance is low. However, in the adsorbent for detoxifying the pollutant according to the present invention, the pH is 12 or more in the strongly basic region. Despite being, the adsorption rate of heavy metals is high.
Metal ions contained in oxides of alkali metals and alkaline earth metals and iron ions contained in iron powder and iron oxide are eluted by the presence of water molecules, and are combined with heavy metals such as arsenic to form a complex. This complex is insoluble in water in a basic atmosphere. This complex ion has a positive charge as a whole. On the other hand, the entire adsorbent for detoxification treatment of the contaminated soil after the metal ions are released has a negative charge, facilitating the adsorption and fixation of complex ions. In this way, it is considered that the heavy metal in the pollutant is adsorbed by the adsorbent for the detoxification treatment of the pollutant.
For this reason, in order to increase the adsorption rate of heavy metals even in a strongly basic region having a high pH, it is necessary to show basicity when an adsorbent for detoxification of pollutants is introduced into pure water. It can be said that the metal oxide attached to a part of the surface of the iron powder on which the film is formed may be an oxide of an alkali metal or an alkaline earth metal.
本発明は、自然由来および又は産業活動に起因した有害物質である重金属による土壌汚染・水質汚染に対する環境保全技術に有効である。 INDUSTRIAL APPLICABILITY The present invention is effective for environmental conservation technology against soil contamination and water pollution by heavy metals that are harmful substances derived from nature and / or industrial activities.
Claims (4)
鉄粉の表面に形成された酸化鉄の酸化膜の一部に、アルカリ金属又はアルカリ土類金属の酸化物である金属酸化物が付着した、塩基性の汚染物質の無害化処理用吸着剤。 An adsorbent for detoxifying a pollutant that adsorbs heavy metals contained in the pollutant and can separate the adsorbed heavy metals,
An adsorbent for detoxifying a basic pollutant, in which a metal oxide that is an oxide of an alkali metal or an alkaline earth metal is attached to a part of an oxide film of iron oxide formed on the surface of iron powder.
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| JPS5651240A (en) * | 1979-10-04 | 1981-05-08 | Nippon Kokan Kk <Nkk> | Treating material for eluted heavy metals and treatment method therefor |
| JP2004076027A (en) * | 2002-08-09 | 2004-03-11 | Sumitomo Metal Ind Ltd | Environmental clean-up material, and manufacturing and operating method therefor |
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