JP2011020007A - Method of extracting organic chlorine compound in contaminated soil - Google Patents
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Abstract
【課題】環境への負荷や電気分解効率の低下を起こすこなく、汚染土壌から効率的に有機塩素化合物を抽出する方法を提供することにある。
【解決手段】有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα‐シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させることを特徴とする、汚染土壌中の有機塩素化合物の抽出方法。
【選択図】図２An object of the present invention is to provide a method for efficiently extracting an organic chlorine compound from contaminated soil without causing an environmental load or a decrease in electrolysis efficiency.
A soil contaminated with an organic chlorine compound is mixed with an aqueous solution containing a nonionic surfactant and α-cyclodextrin, and the organic chlorine compound in the soil is transferred to the aqueous solution. Extraction method of organochlorine compounds in soil.
[Selection] Figure 2
Description
本発明は、ポリ塩化ビフェニル（ＰＣＢ）などの有機塩素化合物で汚染された土壌から有機塩素化合物を抽出する方法に関する。 The present invention relates to a method for extracting an organic chlorine compound from soil contaminated with an organic chlorine compound such as polychlorinated biphenyl (PCB).
土壌汚染や地下水汚染の原因となる物質は多様であるが、とりわけＰＣＢやダイオキシンなどの有機塩素化合物の占める割合が高いのが現状である。既に環境中へ放出された有機塩素化合物に対し、大気・水質などは恒常的なモニタリングと排出抑制が主な対策となるが、土壌に関しては積極的な浄化対策が望まれる。 Substances that cause soil contamination and groundwater contamination are diverse, but the ratio of organic chlorine compounds such as PCB and dioxin is particularly high. For organochlorine compounds that have already been released into the environment, the main measures are air and water quality monitoring and emission control. However, for soil, positive purification measures are desired.
従来から、汚染土壌の浄化方法として、焼却処理、熱脱着処理、洗浄抽出処理等などが実施されている。なかでも、大量に存在するＰＣＢ汚染土壌に対しては、環境負荷が少なく、温和な条件下で実施可能なオンサイト処理技術が要求される。かかる観点から、燃焼による熱や化学処理による分解方式でなく、電気分解によりＰＣＢを分解し無害化する装置および方法が開発されている（特許文献１）。しかしながら、汚染土壌を直接電気分解することは効率的ではないため、本発明者らは、電気分解の前段階処理として、攪拌や超音波などにより物理的洗浄を行なって土粒子に付着した有機塩素化合物を分離する工程や、有機溶媒や界面活性剤による抽出を行なってＰＣＢを土壌から液相に移行させる工程を組み込んだ方法やそれを実施するための装置を開発している（特許文献２）。しかしながら、有機溶媒による抽出は、高濃度では抽出率が優れているものの、低濃度にすると抽出率が低下してしまうという傾向や、また、その種類によっては毒性と臭気の問題があり、繰り返し使用によって周辺環境や作業環境に負荷を与えるという懸念がある。また、界面活性剤は、濃度によって抽出率への影響はないものの、抽出に適正な濃度レベルである１％にすると、汚染土壌抽出後の上澄み液に存在する界面活性剤がＰＣＢと電極との接触を阻害して、電気分解効率を低下させてしまうという問題がある。 Conventionally, incineration processing, thermal desorption processing, washing extraction processing, and the like have been performed as methods for purifying contaminated soil. In particular, on-site treatment technology that can be carried out under mild conditions is required for PCB-contaminated soil that exists in large quantities. From this point of view, an apparatus and a method for decomposing and detoxifying PCB by electrolysis have been developed instead of decomposition by heat or chemical treatment by combustion (Patent Document 1). However, since it is not efficient to electrolyze contaminated soil directly, the present inventors performed organic cleaning by stirring, ultrasonic waves, etc. as a pre-treatment of electrolysis, and organic chlorine adhering to the soil particles. A method incorporating a process of separating a compound, a process of transferring PCB from soil to a liquid phase by performing extraction with an organic solvent or a surfactant, and an apparatus for carrying out the process have been developed (Patent Document 2). . However, although extraction with organic solvents is excellent at high concentrations, the extraction rate tends to decrease at low concentrations, and depending on the type, there are problems of toxicity and odor. There is a concern that it may cause a load on the surrounding environment and work environment. In addition, the surfactant does not affect the extraction rate depending on the concentration, but if the concentration level is 1%, which is appropriate for extraction, the surfactant present in the supernatant liquid after extraction of the contaminated soil will cause the surfactant between the PCB and the electrode. There is a problem that the contact is inhibited and the electrolysis efficiency is lowered.
従って、本発明の課題は、環境への負荷や電気分解効率の低下を起こすことなく、汚染土壌から効率的に有機塩素化合物を抽出する方法を提供することにある。 Accordingly, an object of the present invention is to provide a method for efficiently extracting an organic chlorine compound from contaminated soil without causing an environmental load or a decrease in electrolysis efficiency.
本発明者らは、上記課題を解決すべく鋭意研究を重ねた結果、土壌中の有機塩素化合物の抽出溶媒として、ノニオン系界面活性剤とともにα−シクロデキストリンを添加した水溶液を用いることによって、有機溶媒を使用することなく汚染土壌中から有機塩素化合物を高い抽出率で抽出できること、しかも電気分解の阻害要因である界面活性剤の使用量を低減させることができることを見出し、本発明を完成させるに至った。 As a result of intensive studies to solve the above problems, the present inventors have used an aqueous solution in which α-cyclodextrin is added together with a nonionic surfactant as an extraction solvent for organic chlorine compounds in soil. In order to complete the present invention, it has been found that organochlorine compounds can be extracted from contaminated soil at a high extraction rate without using a solvent, and that the amount of surfactant used as an electrolysis inhibiting factor can be reduced. It came.
すなわち、本発明は以下の発明を包含する。
(1) 有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させることを特徴とする、汚染土壌中の有機塩素化合物の抽出方法。
(2) 前記水溶液中のノニオン系界面活性剤の濃度が０．５〜１．０％である、(1)に記載の抽出方法。
(3) 下記の工程を含む、有機塩素化合物で汚染された土壌の浄化方法。
(a) 有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させる工程
(b) 有機塩素化合物を含む水溶液を土壌と固液分離後、電気分解する工程
(c) 固液分離後の土壌を脱水処理して回収する工程
(4) 前記水溶液中のノニオン系界面活性剤の濃度が０．５〜１．０％である、(3)に記載の浄化方法。
That is, the present invention includes the following inventions.
(1) A soil contaminated with an organic chlorine compound is mixed with an aqueous solution containing a nonionic surfactant and α-cyclodextrin, and the organic chlorine compound in the soil is transferred to the aqueous solution. Extraction method of organochlorine compounds.
(2) The extraction method according to (1), wherein the concentration of the nonionic surfactant in the aqueous solution is 0.5 to 1.0%.
(3) A method for remediating soil contaminated with organochlorine compounds, including the following steps.
(a) mixing an aqueous solution containing a nonionic surfactant and α-cyclodextrin with soil contaminated with an organic chlorine compound, and transferring the organic chlorine compound in the soil to the aqueous solution
(b) A process of electrolyzing an aqueous solution containing an organic chlorine compound after solid-liquid separation from the soil
(c) Process of dewatering and collecting soil after solid-liquid separation
(4) The purification method according to (3), wherein the concentration of the nonionic surfactant in the aqueous solution is 0.5 to 1.0%.
土壌からの有機塩素化合物の抽出溶媒として、ノニオン系界面活性剤のほかにα−シクロデキストリンを添加した水溶液を用いることによって、有機塩素化合物の分解技術の一つである電気分解の阻害要因である界面活性剤の濃度を低減させることができ、しかも抽出率は向上させることができる。抽出溶媒として有機溶媒を用いないので環境負荷が少なく、抽出後の有機溶媒の特殊な処理も不要である。 Using an aqueous solution containing α-cyclodextrin in addition to a nonionic surfactant as an extraction solvent for organochlorine compounds from soil is an inhibitor of electrolysis, one of the organochlorine compound decomposition technologies. The concentration of the surfactant can be reduced, and the extraction rate can be improved. Since no organic solvent is used as the extraction solvent, there is little environmental impact and no special treatment of the organic solvent after extraction is necessary.
以下に、本発明について詳細に述べる。 The present invention will be described in detail below.
１．汚染土壌中の有機塩素化合物の抽出方法
本発明の汚染土壌中の有機塩素化合物の抽出方法は、有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させることを特徴とする。
1. Extraction method of organochlorine compound in contaminated soil The extraction method of organochlorine compound in contaminated soil according to the present invention is a method of mixing an aqueous solution containing a nonionic surfactant and α-cyclodextrin into soil contaminated with an organochlorine compound. The organic chlorine compound in the soil is transferred to the aqueous solution.
本発明の抽出方法で有機塩素化合物を抽出する対象となる汚染土壌としては、有機塩素化合物を含む土壌であれば特に制限はなく、一般の表層土壌のほか、地下土壌、汚泥（産業廃棄物汚泥および一般廃棄物汚泥）、河川・湖沼・港湾の底泥なども含む。 The contaminated soil from which the organic chlorine compound is extracted by the extraction method of the present invention is not particularly limited as long as it contains an organic chlorine compound. In addition to general surface soil, underground soil, sludge (industrial waste sludge) And general waste sludge), rivers, lakes, and harbor bottom mud.
また、本発明の抽出方法で抽出する有機塩素化合物は、代表的には、コプラナーＰＣＢに代表されるポリ塩化ビフェニル（ＰＣＢ）をいうが、ポリ塩化ジベンゾ−P-ジオキシン（ＰＣＤＤ）、ポリ塩化ジベンゾフラン（ＰＣＤＦ）などのダイオキシン類、テトラクロロエチレン、トリクロロエチレン、ジクロロエチレン、トリクロロエタン、四塩化炭素、及びジクロロメタンなどの有機塩素系溶剤、ＤＤＴ類、ＢＨＣ類、アルドリン、エンドリン、ディルドリン、ヘプタクロルなどの有機塩素系農薬も含まれる。 The organic chlorine compound extracted by the extraction method of the present invention is typically polychlorinated biphenyl (PCB) typified by coplanar PCB, but polychlorinated dibenzo-P-dioxin (PCDD), polychlorinated dibenzofuran. Dioxins such as (PCDF), organochlorine pesticides such as tetrachlorethylene, trichloroethylene, dichloroethylene, trichloroethane, carbon tetrachloride, dichloromethane, and other organic chlorine solvents, DDTs, BHCs, aldrin, endrin, dieldrin, and heptachlor are also included. It is.
本発明の抽出方法は、上記汚染土壌から有機塩素化合物を抽出するにあたり、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を抽出溶媒として使用することを特徴とする。 The extraction method of the present invention is characterized in that an aqueous solution containing a nonionic surfactant and α-cyclodextrin is used as an extraction solvent when extracting an organic chlorine compound from the contaminated soil.
ノニオン系界面活性剤としては、ポリオキシエチレンアルキルエーテル（例えば、ポリオキシエチレンラウリルエーテル、ポリオキシエチレンセチルエーテル、ポリオキシエチレンステアリルエーテル、ポリオキシエチレンオレイルエーテルなど）；グリセリン脂肪酸エステル（例えば、グリセロールモノステアレート、グリセロールモノオレエートなど）；ソルビタン脂肪酸エステル（例えば、ソルビタンモノラウレート、ソルビタンモノパルミテート、ソルビタンモノステアレート、ソルビタントリステアレート、ソルビタンモノオレエート、ソルビタントリオレエートなど）；ポリオキシエチレンソルビタン脂肪酸エステル（例えば、ポリオキシエチレンソルビタンモノヤシ油脂肪酸エステル、ポリオキシエチレンソルビタンモノラウレート、ポリオキシエチレンソルビタンモノパルミテート、ポリオキシエチレンソルビタンモノステアレート、ポリオキシエチレンソルビタンモノオレエート、ポリオキシエチレンソルビタントリオレエートなど）；ポリオキシエチレン脂肪酸エステル（例えば、ポリエチレングリコールモノラウレート、ポリエチレングリコールモノステアレート、ポリエチレングリコールジステアレート、ポリエチレングリコールモノオレエートなど）；ポリオキシエチレン誘導体（例えば、ポリオキシエチレンジスチレン化フェニルエーテル、ポリオキシエチレンポリオキシプロピレングリコールなど）；ポリオキシエチレンソルビトール脂肪酸エステル（例えば、テトラオレイン酸ポリオキシエチレンソルビットなど）；プロピレングリコール脂肪酸エステル、ポリオキシエチレンひまし油、ポリオキシエチレン硬化ひまし油、ショ糖脂肪酸エステル（ショ糖ステアリン酸エステル、ショ糖パルミチン酸エステルなど）、ポリグリセリン脂肪酸エステル等が挙げられる。これらのノニオン系界面活性剤は、１種単独で使用することもできるが、２種以上を任意に組み合わせて使用することもできる。本発明においては、ノニオン系界面活性剤としてポリオキシエチレンアルキルエーテルが好適に使用することができる。 Nonionic surfactants include polyoxyethylene alkyl ethers (eg, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether); glycerin fatty acid esters (eg, glycerol monoester) Sorbitan fatty acid esters (eg, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate); polyoxyethylene Sorbitan fatty acid ester (eg, polyoxyethylene sorbitan monococonut oil fatty acid ester, polyoxyethylene sorbitan monolaur Polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc .; polyoxyethylene fatty acid esters (eg, polyethylene glycol monolaurate, Polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, etc.); polyoxyethylene derivatives (eg, polyoxyethylene distyrenated phenyl ether, polyoxyethylene polyoxypropylene glycol, etc.); polyoxyethylene sorbitol Fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate); propylene glycol fatty acid Ester, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, sucrose fatty acid ester (sucrose stearate and sucrose palmitate), polyglycerol fatty acid esters, and the like. These nonionic surfactants can be used alone or in combination of two or more. In the present invention, polyoxyethylene alkyl ether can be suitably used as the nonionic surfactant.
抽出溶媒として用いる水溶液中のノニオン系界面活性剤の濃度は、０．５〜１．０％、好ましくは０．５〜０．７％、より好ましくは０．５％である。また、水溶液中のα−シクロデキストリンの濃度は、０．１〜０．３％、より好ましくは０．１〜０．２％である。 The concentration of the nonionic surfactant in the aqueous solution used as the extraction solvent is 0.5 to 1.0%, preferably 0.5 to 0.7%, more preferably 0.5%. The concentration of α-cyclodextrin in the aqueous solution is 0.1 to 0.3%, more preferably 0.1 to 0.2%.
後述する実施例に示すように、本発明の抽出方法は、ノニオン系界面活性剤とα−シクロデキストリンを組み合わせて使用することによって、電気分解の阻害要因となるノニオン系界面活性剤の濃度を低減、具体的には、１％から０．５％まで低減させることでき、かつ、ノニオン系界面活性剤単独よりも優れた抽出率が得られる。 As shown in the examples described later, the extraction method of the present invention reduces the concentration of nonionic surfactant, which is an inhibitory factor for electrolysis, by using a combination of nonionic surfactant and α-cyclodextrin. Specifically, it can be reduced from 1% to 0.5%, and an extraction rate superior to that of the nonionic surfactant alone can be obtained.
抽出溶媒のｐＨは、抽出を阻害しない限り特に制限はされないが、好ましくは４．０〜９．０、より好ましくは５．６〜８．５の範囲に適宜調節する。 The pH of the extraction solvent is not particularly limited as long as it does not inhibit the extraction, but is preferably adjusted appropriately within the range of 4.0 to 9.0, more preferably 5.6 to 8.5.
抽出温度も特に制限されず、好ましくは１０〜４０℃、より好ましくは２０〜３０℃の範囲で適宜設定することができる。 The extraction temperature is not particularly limited, and can be appropriately set within a range of preferably 10 to 40 ° C, more preferably 20 to 30 ° C.
抽出は、汚染土壌と抽出溶媒を混合することによって行う。土壌と抽出溶媒との割合は、汚染土壌に含まれている有機塩素化合物量に応じて、適宜設定すればよく、特に制限はされないが、土壌１重量部に対する抽出溶媒の割合として、例えば、３〜５重量部、より好ましくは４重量部を例示することができる。 Extraction is performed by mixing contaminated soil and extraction solvent. The ratio of the soil and the extraction solvent may be set as appropriate according to the amount of the organic chlorine compound contained in the contaminated soil, and is not particularly limited. For example, the ratio of the extraction solvent to 1 part by weight of the soil is 3 -5 parts by weight, more preferably 4 parts by weight can be exemplified.
上記の汚染土壌と抽出溶媒を混合は、土壌が抽出溶媒によく分散して接触面積が大きくなるような条件下での混合であればよく、例えば攪拌混合、振盪混合、または超音波処理下での混合を挙げることができるが、好ましくは攪拌混合である。攪拌混合を行う場合は、攪拌速度を２００〜３００ｒｐｍで行うことが好ましい。 The above contaminated soil and extraction solvent may be mixed as long as the soil is well dispersed in the extraction solvent and increases the contact area. For example, under stirring, shaking, or sonication. However, stirring and mixing are preferable. When stirring and mixing, the stirring speed is preferably 200 to 300 rpm.
このように汚染土壌と上記抽出溶媒とを混合することにより、土壌中の有機塩素化合物を効率よくかつ速やかに抽出溶媒（水溶液）へ移行させることができる。本発明の抽出方法によれば、１０〜１５分間、好ましくは１０分間で土壌から有機塩素化合物を抽出することが可能である。 Thus, by mixing contaminated soil and the said extraction solvent, the organic chlorine compound in soil can be efficiently and rapidly transferred to an extraction solvent (aqueous solution). According to the extraction method of the present invention, it is possible to extract an organochlorine compound from soil in 10 to 15 minutes, preferably 10 minutes.
上記のような抽出操作は、汚染土壌に含まれている有機塩素化合物量に応じて回数を増やしてもよく、例えば２〜５回繰り返してもよい。 The above extraction operation may increase the number of times according to the amount of the organic chlorine compound contained in the contaminated soil, and may be repeated, for example, 2 to 5 times.
後述する実施例に示すように、抽出溶媒としてノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を使用する場合、ノニオン系界面活性剤のみを含む水溶液に使用する場合に比べて抽出率を有意に向上させ、界面活性剤の使用量を低減させることが出来る。結果としてその後の工程で行なう有機塩素化合物の電気分解を効率よく行なうことができる。 As shown in the examples described later, when an aqueous solution containing a nonionic surfactant and α-cyclodextrin is used as an extraction solvent, the extraction rate is significant compared to the case of using an aqueous solution containing only a nonionic surfactant. The amount of the surfactant used can be reduced. As a result, the electrolysis of the organochlorine compound performed in the subsequent steps can be performed efficiently.
２．汚染土壌の浄化方法
上記のとおり、本発明の抽出方法は汚染土壌から効率よく有機塩素化合物を抽出除去できるので土壌の浄化方法にも有効に利用することができる。
2. As described above, the extraction method of the present invention can efficiently extract and remove organochlorine compounds from the contaminated soil, so that it can also be effectively used in a soil purification method.
従って、本発明によればまた、有機塩素化合物を汚染土壌から分離するともに無害化する汚染土壌の浄化方法もまた提供される。 Therefore, according to the present invention, there is also provided a method for purifying contaminated soil that separates and detoxifies organochlorine compounds from contaminated soil.
本発明の汚染土壌の浄化方法は、上記の抽出方法を用いて容器内で汚染土壌にノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させた後、有機塩素化合物を含有した上澄み液を別の容器に移し、該容器内に通電させることにより有機塩素化合物の電気分解を行なって脱塩素化し、一方、有機塩素化合物が除去された土壌を脱水処理して回収することにより行なう。 In the method for purifying contaminated soil of the present invention, an aqueous solution containing a nonionic surfactant and α-cyclodextrin is mixed in the contaminated soil in the container using the above extraction method, and the organic chlorine compound in the soil is added to the aqueous solution. After the transfer, the supernatant containing the organic chlorine compound was transferred to another container, and the organic chlorine compound was electrolyzed and dechlorinated by energizing the container, while the organic chlorine compound was removed. This is done by dehydrating and collecting the soil.
すなわち、本発明の汚染土壌の浄化方法は、基本的に下記の(a)〜(c)の工程を含む：
(a) 有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させる工程（抽出工程）
(b) 有機塩素化合物を含む水溶液を土壌と固液分離後、電気分解する工程(脱塩素化工程）
(c) 固液分離後の土壌を脱水処理して回収する工程(再生工程）
That is, the contaminated soil purification method of the present invention basically includes the following steps (a) to (c):
(a) Step of mixing an aqueous solution containing a nonionic surfactant and α-cyclodextrin with soil contaminated with an organic chlorine compound, and transferring the organic chlorine compound in the soil to the aqueous solution (extraction step)
(b) A process of electrolyzing an aqueous solution containing an organic chlorine compound after solid-liquid separation from soil (dechlorination process)
(c) Process of dewatering and recovering soil after solid-liquid separation (regeneration process)
(a)の抽出工程は、汚染土壌から有機塩素化合物を抽出する工程であり、先の１．で説明した方法に従って実施することができる。当該抽出工程により、汚染土壌から有機塩素化合物を分離して抽出溶媒である水溶液中に移行させることができる。また、本工程においては、土粒子に付着した有機塩素化合物を土粒子から分離しやすくし、その後の工程の電気分解に要する時間を短縮化するために、超音波を発生させてもよい。 The extraction step (a) is a step of extracting an organochlorine compound from the contaminated soil. It can be carried out according to the method described in. By this extraction step, the organic chlorine compound can be separated from the contaminated soil and transferred into an aqueous solution that is an extraction solvent. In this step, ultrasonic waves may be generated in order to facilitate separation of the organic chlorine compound adhering to the soil particles from the soil particles and shorten the time required for the electrolysis in the subsequent step.
(b)の脱塩素化工程では、(a)の抽出工程で有機塩素化合物が移行した水溶液を土壌と固液分離後、電気分解することにより無害化する。固液分離は、静置または遠心分離することにより行なう。通常、所定時間静置すれば、有機塩素化合物が分離された土粒子は容器内に沈積し、難溶性の有機塩素化合物は上澄み液内を浮遊した状態となる。 In the dechlorination step (b), the aqueous solution to which the organochlorine compound has been transferred in the extraction step (a) is solidified from the soil and then detoxified by electrolysis. Solid-liquid separation is performed by standing or centrifuging. Normally, when left standing for a predetermined time, the soil particles from which the organic chlorine compound has been separated are deposited in the container, and the hardly soluble organic chlorine compound is in a state of floating in the supernatant.
固液分離により回収した有機塩素化合物を含有する水溶液（液相）は、電気分解に供する。電気分解することにより、陰極には脱塩素化された無害のビフェニルが付着し、陽極には塩素イオンと水中のカルシウムやカリウムなどからなる塩化化合物が付着する。また、電気分解も電気分解槽内に超音波を発生させながら行なってもよい。 The aqueous solution (liquid phase) containing the organic chlorine compound recovered by solid-liquid separation is subjected to electrolysis. By electrolysis, the harmless biphenyl dechlorinated adheres to the cathode, and a chloride compound composed of chlorine ions and calcium or potassium in water adheres to the anode. Electrolysis may also be performed while generating ultrasonic waves in the electrolysis tank.
図１は、本発明の汚染土壌の抽出・浄化方法の一実施形態を示したものである。前記抽出方法を行なうための抽出装置は、混和槽、当該混和槽にノニオン系界面活性剤とα−シクロデキストリンを含有する水溶液を注入するための管、当該に汚染土壌を投入するためのホッパー、および攪拌部材を少なくとも備える。抽出装置の実施形態として、例えば、容器内に鉛直方向の隔壁を設けておき、隔壁の一側側には先端にプロペラを備えた撹拌部材を設置しておき、隔壁の一方の側には水中ポンプを設置しておく。隔壁の他の一方の側には予めノニオン系界面活性剤とα−シクロデキストリンを含有する水溶液が入っており、土砂投入ホッパーから汚染土壌を投入する。汚染土壌から有機塩素化合物を分離し、該有機塩素化合物が浮遊する上澄み液ができた段階で隔壁の上部から他の一方の側へ上澄み液を流入させる。この上澄み液（洗浄液）を水中ポンプでポンプアップしながら電気分解装置へ送る。一方、抽出装置を構成する混和槽内に沈積した有機塩素化合物が分離除去された土壌は、例えば容器内に設置したサンドポンプにてポンプアップするなどして脱水装置に送り、回収する。脱水回収された土砂は別途工事の埋め戻し土などに有効利用することが可能となる。 FIG. 1 shows one embodiment of a method for extracting and purifying contaminated soil according to the present invention. An extraction apparatus for performing the extraction method includes a mixing tank, a tube for injecting an aqueous solution containing a nonionic surfactant and α-cyclodextrin into the mixing tank, a hopper for introducing contaminated soil into the mixing tank, And at least a stirring member. As an embodiment of the extraction device, for example, a vertical partition is provided in the container, a stirring member provided with a propeller at the tip is installed on one side of the partition, and a submerged portion is placed on one side of the partition. Install the pump. On the other side of the partition wall, an aqueous solution containing a nonionic surfactant and α-cyclodextrin is contained in advance, and contaminated soil is introduced from a soil and sand injection hopper. The organic chlorine compound is separated from the contaminated soil, and the supernatant liquid is allowed to flow from the upper part of the partition wall to the other side when the supernatant liquid in which the organic chlorine compound floats is formed. This supernatant liquid (cleaning liquid) is sent to the electrolysis apparatus while being pumped up by a submersible pump. On the other hand, the soil from which the organic chlorine compound deposited in the mixing tank constituting the extraction device is separated and removed is sent to a dehydration device, for example, by being pumped up by a sand pump installed in the container. The dewatered and collected earth and sand can be effectively used as backfill soil for separate construction.
以下、実施例により本発明をさらに具体的に説明する。但し、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.
（実施例１）PCB抽出試験
蒸留水にノニオン系界面活性剤（ポリオキシエチレンアルキルエーテル：エマルゲン1108（花王社製)）とα-シクロデキストリンを添加して洗浄液を作製した。まず、蒸留水にノニオン系界面活性剤の濃度が0、0.1、0.5、1.0％となるように添加し、このノニオン系界面活性剤濃度の異なる蒸留水にそれぞれα−シクロデキストリンを0.2％となるように添加した（試験ケースNo.1〜4）。
(Example 1) PCB extraction test A nonionic surfactant (polyoxyethylene alkyl ether: Emulgen 1108 (manufactured by Kao Corporation)) and α-cyclodextrin were added to distilled water to prepare a washing solution. First, nonionic surfactant is added to distilled water so that the concentration of nonionic surfactant is 0, 0.1, 0.5, 1.0%, and α-cyclodextrin is 0.2% in distilled water having different nonionic surfactant concentrations. (Test cases No. 1 to 4).
また、α−シクロデキストリンに代えて、β−シクロデキストリンを0.2％となるように添加した洗浄液（試験ケースNo.5〜8）、γ−シクロデキストリンを0.3％となるように添加した洗浄液（試験ケースNo.9〜12）、シクロデキストリンを添加しない洗浄液（試験ケースNo.13〜15）も同様にして作製した。 Also, instead of α-cyclodextrin, β-cyclodextrin was added so as to be 0.2% (test cases No. 5 to 8), and γ-cyclodextrin was added so as to be 0.3% (test Cases No. 9 to 12) and a cleaning solution without addition of cyclodextrin (test cases No. 13 to 15) were prepared in the same manner.
50mLのガラス製共栓付遠心沈殿管に濃度既知（平均443mg/kg）のPCB含有土壌試料を10ｇ、上記で調製したノニオン系界面活性剤濃度の異なる各洗浄液40mLを入れ、往復振とう機を用いて200rpmの条件で10分間振とうすることによって洗浄した。この洗浄操作は４回行なった。１回洗浄ごとに静置した上澄み液を採取し、遠心分離機により2000rpmで10分間遠心分離を行ない、液相を50 mLガラス製ネジ口瓶に分取した。 Place 10g of PCB-containing soil sample with a known concentration (average 443mg / kg) in a 50mL glass stoppered centrifugal sedimentation tube, and 40mL of each cleaning solution with different nonionic surfactant concentrations prepared above. It was washed by shaking for 10 minutes at 200 rpm. This washing operation was performed four times. The supernatant liquid that was allowed to stand after each washing was collected, centrifuged at 2000 rpm for 10 minutes with a centrifuge, and the liquid phase was fractionated into 50 mL glass screw cap bottles.
上記の液相10mlをサンプリングし、これにｎ−ヘキサン100mlを添加し、10分間の振とうして抽出した。抽出後の試料を、ガスクロマトグラフ質量分析（ＧＣ／ＭＳ）にかけ、液相中のPCB濃度を測定した。測定したPCB濃度から求めた液相（抽出液）中のPCB含有量と初期のPCB土壌含有量からPCB抽出率を算出した。結果を表１に示す。 10 ml of the above liquid phase was sampled, 100 ml of n-hexane was added thereto, and extracted by shaking for 10 minutes. The sample after extraction was subjected to gas chromatograph mass spectrometry (GC / MS), and the PCB concentration in the liquid phase was measured. The PCB extraction rate was calculated from the PCB content in the liquid phase (extract) obtained from the measured PCB concentration and the initial PCB soil content. The results are shown in Table 1.
また、図２に、ノニオン系界面活性剤の濃度とPCB抽出率との関係を、シクロデキストリンの種類別に示す。図２に示されるように、ノニオン系界面活性剤単独を1.0％濃度で使用した場合PCB抽出率が約69％であるのに対し、α-シクロデキストリン（0.2%)を併用するとPCB抽出率が約87％と飛躍的に増加し、しかも、ノニオン系界面活性剤の使用濃度を0.5％にしても約PCB抽出率が約86％とほぼ同じあった。 FIG. 2 shows the relationship between the concentration of nonionic surfactant and the PCB extraction rate for each type of cyclodextrin. As shown in Fig. 2, when the nonionic surfactant alone is used at a concentration of 1.0%, the PCB extraction rate is about 69%, whereas when α-cyclodextrin (0.2%) is used in combination, the PCB extraction rate is The PCB extraction rate was about the same as about 86% even when the concentration of nonionic surfactant used was 0.5%.
Claims (4)
(a) 有機塩素化合物で汚染された土壌に、ノニオン系界面活性剤とα−シクロデキストリンを含む水溶液を混合し、該水溶液に土壌中の有機塩素化合物を移行させる工程
(b) 有機塩素化合物を含む水溶液を土壌と固液分離後、電気分解する工程
(c) 固液分離後の土壌を脱水処理して回収する工程 A method for purifying soil contaminated with organochlorine compounds, comprising the following steps.
(a) A step of mixing an aqueous solution containing a nonionic surfactant and α-cyclodextrin with soil contaminated with an organic chlorine compound, and transferring the organic chlorine compound in the soil to the aqueous solution
(b) A process of electrolyzing an aqueous solution containing an organic chlorine compound after solid-liquid separation from soil
(c) Process of dewatering and collecting soil after solid-liquid separation
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