JP2004026753A - Method for recovering organic substance from waste water containing methylene-bridged polyarylpolyamine - Google Patents
Method for recovering organic substance from waste water containing methylene-bridged polyarylpolyamine Download PDFInfo
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Abstract
<P>PROBLEM TO BE SOLVED: To provide an efficient method for recovering organic substances with low environmental impact as an improved method for recovering aniline or amines such as methylene-bridged polyarylpolyamine (hereinafter referred to as MDA) dissolved in a waste water layer after neutralization of a reaction mixture by an aqueous alkaline solution and separation in the post-treatment process for production of MDA obtained by condensation of aniline and formaldehyde in the presence of an acid catalyst such as hydrochloric acid. <P>SOLUTION: This method for recovering organic substances from the MDA-containing waste water comprises neutralizing, by the aqueous alkaline solution, the MDA-containing reaction mixture obtained by the condensation of aniline and formaldehyde in the presence of the acid catalyst, separating the waste water layer from an oil layer, and then extracting the organic substance from the waste water layer by adding thereto 10-40 pts.wt. toluene based on 100 pts.wt. waste water to separate the substance remaining in the waste water together with toluene. <P>COPYRIGHT: (C)2004,JPO
Description
【0001】
【発明の技術分野】
本発明は、アニリンとホルムアルデヒドとを塩酸などの酸触媒存在下で縮合させて得られるメチレン架橋ポリアリールポリアミン(以下、MDAと略す)製造の後処理工程において、得られた反応混合物をアルカリ水溶液で中和・分液した後の廃水層中に溶解している有機物の回収方法に関する。より詳しくは、本発明は、アニリンあるいはMDAなどのアミン分含有廃水からの環境負荷が小さく、効率的な有機物の回収方法に関する。
【0002】
【発明の技術的背景】
MDA(メチレン架橋ポリアリールポリアミン)は、エポキシ樹脂やポリウレタン樹脂の硬化剤として、さらにはホスゲン化して、ポリメチレンポリアリールポリイソシアネートとして硬質フォーム、半硬質フォーム、エラストマーなどのポリウレタン樹脂の原料として使用されている。このMDAは、下記一般式(I)で表すことができる。
【0003】
【化1】
このようなMDAの製造に際して、MDA縮合工程に伴い生ずる廃水からの有機溶媒による有機物の抽出回収については、既に特開平4−154744号公報にそのプロセスが開示されている。
前記公報には、抽出溶媒に用いることができる有機溶媒として種々の溶媒が挙げられているが、実際にはベンゼンが用いられている。この理由としては、アニリン製造の原料(ベンゼンのニトロ化・水添)として多用されており抽出溶媒としての利便性に富むこと、また、廃水層中に溶解しているアニリンあるいはMDAなどのアミン分との相溶性・抽出効率が良好であること、さらに廃水層との良好な分液性を有しており、抽剤としての性能も好適であることなどが挙げられる。このように、MDA製造の後処理工程においては、廃水層中に溶解しているアニリンあるいはMDAなどのアミン分は、ベンゼンによる抽出分離法により回収されていた。
【0005】
しかしながら、MDA製造の後処理工程において、MDA含有反応混合物をアルカリ水溶液で中和・分液した後の廃水層中に溶解しているアニリンあるいはMDAなどのアミン分をベンゼンで抽出分離する場合には、抽剤であるベンゼンの廃水中へのわずかな溶解に基づく水系への微量流出および大気中への拡散などの可能性があり、環境に対する負荷がより低減された分離方法への転換が求められている。
【0006】
本発明者らは、上記実情に鑑みて鋭意研究した結果、抽剤としてトルエンを、廃水に対して特定の割合で用いることにより、廃水層からの有機物の抽出効率を下げることなく、環境への負荷を低減しうることを見出して、本発明を完成するに至った。
【0007】
【発明の目的】
本発明は、MDA製造の後処理工程における、MDA含有反応混合物をアルカリ水溶液で中和・分液した後の廃水層中に溶解しているアニリンあるいはMDAなどのアミン分の改良された回収方法として、環境への負荷が小さく、効率的な有機物の回収方法を提供することを目的としている。
【0008】
【発明の概要】
本発明にかかるメチレン架橋ポリアリールポリアミン含有廃水からの有機物の回収方法は、
アニリンとホルムアルデヒドとを酸触媒存在下で縮合させて得られるメチレン架橋ポリアリールポリアミン含有反応混合物をアルカリ水溶液で中和した後、油層と廃水層を分離し、
該廃水層100重量部に対してトルエンを10〜40重量部の量で用いて、該廃水層をトルエン抽出することにより、廃水層に残存する有機物をトルエンとともに分離することを特徴としている。
【0009】
また、本発明では、上記のような廃水層に残存する有機物をトルエンとともに分離した後、規則充填物を蒸留搭上部に備えた蒸留装置により蒸留分離し、トルエンと有機物を回収使用することを特徴としている。
このように本発明にかかるメチレン架橋ポリアリールポリアミン含有廃水からの有機物の回収方法は、MDA含有廃水中の有機物を低減し、アニリン回収率およびMDA収率を向上させた効率的な有機物の回収方法であるとともに、環境に対する負荷をも小さくしうる。
【0010】
【発明の具体的説明】
以下、本発明について具体的に説明する。
本発明におけるMDAの合成は、公知の方法にて製造される。
すなわち、アニリンとホルムアルデヒドを塩酸などの酸触媒の存在下で縮合させ、反応終了後、過剰の苛性ソーダにより酸触媒を中和し、これを油層と水層とに分液し、さらに該油層を水洗・分液した後、この油層からMDAを得ることができる。
【0011】
具体的には、アニリンとホルマリン(アニリン/ホルマリンのモル比:約1〜5)を、塩酸触媒(塩酸/アニリンのモル比:約0.05〜1)存在下で加熱することにより、縮合反応させ、その後の転位反応により、MDAを合成する。代表的な加熱条件は、縮合反応では約70℃以下であることが好ましく、また、転位反応では約90℃以上であることが好ましく、連続法でもバッチ法でも製造することができる。
【0012】
前記縮合・転位反応終了後のMDA含有反応混合物中には、MDA以外にアニリン、水、塩などが含まれており、使用した塩酸に対して過剰の苛性ソーダを加えることにより、中和・分液が行われる。このようにして得られた油層を、水洗・分液した後、さらに含まれているアニリンおよび水を蒸留分離(脱アニリン工程)することにより、MDAが得られる。
【0013】
中和・分液した後の水層ならびに水洗・分液後の水層(以下、廃水層という。)中には、アニリン、MDAなどの有機物が残存していることから、この有機物を抽剤による抽出分離操作によって回収する。その後、回収液中の抽剤は、有機物(アニリン、MDA)から蒸留操作により分離される。分離された抽剤は、リサイクル使用により再度抽出に用いられる。また、分離された有機物(アニリン、MDA)についても回収され、アニリンとホルマリンとの縮合工程あるいは脱アニリン工程にリサイクルされる。
【0014】
一方、有機物が抽出分離された後の廃水については、一般に廃水処理設備で処分される。この有機物抽出分離後の廃水中には、極微量であるが抽剤が溶解しており、廃水処理設備で処分する前に、この廃水溶解分の抽剤をストリッピング処理などの方法により除去することが行われている。
本発明では、上記MDA含有反応混合物をアルカリ水溶液で中和した後、油層を分離した廃水層100重量部に対して、トルエンを10〜40重量部の量で用いて、該廃水層をトルエン抽出することにより、廃水層に残存する有機物をトルエンとともに分離する。
【0015】
なお、本明細書において廃水層とは、前述したように、中和・分液した後の水層、中和・分液した後の油層を水洗・分液して得られた水層、もしくはこれらの両方を合わせたものをいう。
本発明のMDA含有廃水からの有機物の回収方法では、抽剤として用いるトルエンは、廃水層100重量部に対して、通常10〜40重量部、好ましくは22〜40重量部、より好ましくは23〜40重量部の量で用いられる。抽剤としてトルエンを、廃水層100重量部に対して10重量部以上、好ましくは22重量部以上の量で用いることにより、ベンゼンと同等以上の有機物の抽出性能を発揮させることができるため望ましい。また、上記トルエンの量を廃水層100重量部に対して40重量部以下の量とすることにより、トルエンの回収リサイクルコストを低減しつつ有機物の回収率を高く維持することができるため、好ましい。
【0016】
廃水層中の有機物をトルエンで抽出する方法としては、バッチ法、連続法、向流方式、永田式などのいずれの方法を用いてもよいが、向流接触方式が抽出効率面からは好ましい。また、抽出操作は、約5〜90℃の温度範囲で行うことができる。
また、廃水層中の有機物(アニリン、MDAなど)を抽出分離した後のトルエン(以下、有機物含有トルエンという。)から、トルエンを分離回収するために蒸留操作を行うが、この際に該有機物含有トルエンは有機物以外に水や塩も含有しているため、それらにより、蒸留塔内に詰まりが発生し、差圧が増加するため、塔内を定期的に洗浄する必要が生じて、作業効率が低下する。
【0017】
本発明のMDA含有廃水からの有機物の回収方法では、この詰まりによる差圧の増大速度を抑制し、より長期間安定して運転するために、蒸留塔上部(濃縮部)、好ましくは搭頂部に、規則充填物を備えた蒸留装置により、有機物含有トルエンからトルエンと有機物とを、蒸留分離し、トルエンと有機物を回収使用する。
【0018】
このような蒸留装置に充填される規則充填物としては、たとえば、メッシュタイプ、シートタイプ、テクノパック、モンツパック、スルザーパックなどが挙げられる。
また、蒸留塔の供給部および、供給部の直上部には、バルブトレー、シーブトレー、バルブキャップトレーなどの閉塞に強いトレーを用いることが好ましい。さらに、蒸留塔の回収部には、ラシヒスーパーリング、カスケードミニリング、IMTPなどの不規則充填物を用いてもよい。
【0019】
本発明では、特に有機物含有トルエンの供給部から上部、すなわち濃縮部である搭上部、好ましくは搭頂部に規則充填物が充填された蒸留塔を用いて、トルエンとアニリンなどを分離回収する方法が好ましい。
【0020】
【実施例】
以下、図1を参照して、実施例に基づいて本発明をさらに具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
【0021】
【実施例1】
アニリン、ホルマリン、塩酸、水を接触させて得られたMDA含有反応混合物を苛性ソーダで中和した後、分液槽内で分液し、水層部−1を695kg/h、油層部を、555kg/hの速度で抜き出した。得られた油層部を、さらに200kg/hの温水で水洗、油水分離し、230kg/hの速度で水層部−2を抜き出した。
【0022】
前記水層部−1および水層部−2を混合して、混合廃水を得た(アニリン含量8,500ppm、MDA含量2,000ppm)。
この混合廃水を図1に示した連続向流接触方式の抽出工程にしたがって、トルエン抽出した。すなわち、この混合廃水925kg/h(図中▲1▼)をトルエンと向流2段接触(図中1a、1b)させることにより、廃水中のアニリン、MDAなどの有機物を抽出した。
【0023】
抽出分離工程としては、混合廃水925kg/h(図中▲1▼)と2段目の分液槽(図中1b)より分液されたトルエン211kg/h(図中▲3▼)とを向流接触させ、60℃に設定した1段目の分液槽(図中1a)にて廃水層(図中▲2▼)とトルエン層(図中▲4▼)に分液させた。廃水層916kg/h(図中▲2▼)は、トルエン209kg/h(図中▲5▼)と向流接触させ、60℃に設定した2段目の分液槽(図中1b)にて廃水層(図中▲7▼)とトルエン層(図中▲3▼)に分液させた。
【0024】
1段目の抽出分液槽(図中1a)で分液した220kg/hのトルエン(図中▲4▼)を、規則充填物を蒸留搭上部に備えた連続蒸留装置(図中2)にてトルエン留去を行った結果、11kg/hの有機物(アニリン、MDAなど)が得られた。この有機物を、脱アニリン工程に回収リサイクルすることにより、廃水中のアニリンとMDAを回収分離した。
【0025】
抽出後の廃水(図中▲7▼)中のアニリン含量は210ppm、MDAは不検出であった。また、この抽出後廃水中のトルエン含量は、130ppmであった。
【0026】
【比較例1】
トルエンの代わりにベンゼン175kg/hを用いた以外は実施例1と同様に実施した。その結果、抽出後の廃水(図中▲7▼)中のアニリン含量は220ppm、MDAは不検出であった。また、この抽出後廃水中のベンゼン含量は、220ppmであった。
【0027】
【発明の効果】
本発明によれば、抽剤としてベンゼンを用いないため、環境に対する負荷が小さい上、ベンゼンと同等以上の廃水層からの有機物の抽出性能を確保できることから、MDA製造の後処理工程において、廃水層中に残存する有機物を環境への負荷が小さい方法で効率的に回収することができる。さらには、廃水中の抽出溶媒の残存量を低く保つことができるため、廃水処理もより簡便に実施できる。
【0028】
また、本発明によれば、蒸留搭上部に規則充填物を備えた蒸留装置を用いることにより、廃水層中の有機物を抽出分離した後のトルエンから、トルエンと有機物とを作業効率よく蒸留分離し、トルエンと有機物を効率的に回収使用することができる。
【図面の簡単な説明】
【図1】図1は、連続向流接触方式の抽出工程図である。
【符号の説明】
1a、1b: 抽出分液槽
2: 規則充填物を備えた蒸留塔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a methylene-crosslinked polyarylpolyamine (hereinafter abbreviated as MDA) produced by condensing aniline and formaldehyde in the presence of an acid catalyst such as hydrochloric acid, in a post-treatment step of producing the methylene-crosslinked polyarylpolyamine. The present invention relates to a method for recovering organic matter dissolved in a wastewater layer after neutralization and liquid separation. More specifically, the present invention relates to a method for efficiently recovering organic substances with low environmental load from wastewater containing amine components such as aniline or MDA.
[0002]
[Technical Background of the Invention]
MDA (methylene-crosslinked polyarylpolyamine) is used as a curing agent for epoxy resins and polyurethane resins, and further phosgenated, and used as a raw material for polyurethane resins such as rigid foams, semi-rigid foams, and elastomers as polymethylene polyarylpolyisocyanates ing. This MDA can be represented by the following general formula (I).
[0003]
Embedded image
[0004]
In the production of such MDA, extraction and recovery of organic substances from wastewater by an organic solvent in the MDA condensation step has already been disclosed in Japanese Patent Application Laid-Open No. 4-154744.
The publication discloses various solvents as organic solvents that can be used as the extraction solvent, but benzene is actually used. The reason for this is that it is frequently used as a raw material (nitration / hydrogenation of benzene) for the production of aniline, and is very convenient as an extraction solvent. In addition, amine components such as aniline or MDA dissolved in a wastewater layer are dissolved. And good extraction efficiency, and has good liquid separation properties with the wastewater layer, and also has suitable performance as an extractant. As described above, in the post-treatment process of MDA production, amine components such as aniline or MDA dissolved in the wastewater layer were recovered by the extraction separation method using benzene.
[0005]
However, in the post-treatment step of MDA production, when the MDA-containing reaction mixture is neutralized and separated with an aqueous alkali solution, and the amine component such as aniline or MDA dissolved in the waste water layer is extracted and separated with benzene, There is a possibility that a small amount of benzene, an extractant, dissolves in wastewater due to slight dissolution into water systems and diffusion into the atmosphere.Therefore, it is necessary to switch to a separation method that reduces the burden on the environment. ing.
[0006]
The present inventors have conducted intensive studies in view of the above-mentioned circumstances, and as a result, by using toluene as an extractant at a specific ratio with respect to wastewater, without lowering the extraction efficiency of organic substances from the wastewater layer, it is possible to reduce the environmental impact. The inventors have found that the load can be reduced, and have completed the present invention.
[0007]
[Object of the invention]
The present invention provides an improved method for recovering an amine such as aniline or MDA dissolved in a wastewater layer after neutralizing and separating a MDA-containing reaction mixture with an aqueous alkali solution in a post-treatment step of MDA production. Another object of the present invention is to provide a method for efficiently collecting organic substances, which has a small impact on the environment.
[0008]
Summary of the Invention
The method for recovering organic matter from methylene-crosslinked polyarylpolyamine-containing wastewater according to the present invention comprises:
After neutralizing a methylene-crosslinked polyarylpolyamine-containing reaction mixture obtained by condensing aniline and formaldehyde in the presence of an acid catalyst with an aqueous alkali solution, separating an oil layer and a wastewater layer,
By extracting toluene with 10 to 40 parts by weight of toluene with respect to 100 parts by weight of the wastewater layer and extracting the wastewater with toluene, organic substances remaining in the wastewater layer are separated together with toluene.
[0009]
Further, the present invention is characterized in that, after separating the organic matter remaining in the wastewater layer together with toluene as described above, the ordered packing is separated by distillation using a distillation apparatus provided at the top of the distillation column, and the toluene and the organic matter are recovered and used. And
As described above, the method for recovering organic matter from methylene-crosslinked polyarylpolyamine-containing wastewater according to the present invention reduces the amount of organic matter in MDA-containing wastewater and improves the aniline recovery rate and MDA yield. In addition, the load on the environment can be reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described specifically.
The synthesis of MDA in the present invention is produced by a known method.
That is, aniline and formaldehyde are condensed in the presence of an acid catalyst such as hydrochloric acid, and after completion of the reaction, the acid catalyst is neutralized with an excess of caustic soda, separated into an oil layer and an aqueous layer, and the oil layer is further washed with water. -After liquid separation, MDA can be obtained from this oil layer.
[0011]
Specifically, the condensation reaction is carried out by heating aniline and formalin (molar ratio of aniline / formalin: about 1 to 5) in the presence of a hydrochloric acid catalyst (molar ratio of hydrochloric acid / aniline: about 0.05 to 1). And MDA is synthesized by the subsequent rearrangement reaction. Typical heating conditions are preferably about 70 ° C. or less for the condensation reaction, and about 90 ° C. or more for the rearrangement reaction, and can be produced by a continuous method or a batch method.
[0012]
The MDA-containing reaction mixture after the completion of the condensation / rearrangement reaction contains aniline, water, salt, etc. in addition to MDA, and is neutralized and separated by adding an excess of caustic soda to the hydrochloric acid used. Is performed. After the thus obtained oil layer is washed and separated, MDA can be obtained by further separating and separating the contained aniline and water (dianiline removal step).
[0013]
The organic layer such as aniline and MDA remains in the aqueous layer after neutralization and liquid separation and the aqueous layer after washing and liquid separation (hereinafter referred to as a waste water layer). Recovered by an extraction separation operation. Thereafter, the extractant in the recovered liquid is separated from organic substances (aniline, MDA) by a distillation operation. The separated extractant is used again for extraction by recycling. The separated organic substances (aniline, MDA) are also collected and recycled to the condensation step of aniline and formalin or the deaniline removal step.
[0014]
On the other hand, wastewater from which organic matter has been extracted and separated is generally disposed of in a wastewater treatment facility. A very small amount of extractant is dissolved in the wastewater after the organic matter extraction separation, and the extractant of the dissolved wastewater is removed by a method such as stripping treatment before disposal in a wastewater treatment facility. That is being done.
In the present invention, after neutralizing the MDA-containing reaction mixture with an aqueous alkali solution, toluene is used in an amount of 10 to 40 parts by weight with respect to 100 parts by weight of a wastewater layer from which an oil layer is separated, and the wastewater layer is extracted with toluene. By doing so, the organic matter remaining in the wastewater layer is separated together with the toluene.
[0015]
In this specification, the wastewater layer is, as described above, an aqueous layer after neutralization and liquid separation, an aqueous layer obtained by washing and separating an oil layer after neutralization and liquid separation, or It refers to a combination of both of these.
In the method for recovering organic matter from MDA-containing wastewater of the present invention, toluene used as an extractant is usually 10 to 40 parts by weight, preferably 22 to 40 parts by weight, more preferably 23 to 40 parts by weight, based on 100 parts by weight of a wastewater layer. It is used in an amount of 40 parts by weight. It is desirable to use toluene as an extractant in an amount of 10 parts by weight or more, preferably 22 parts by weight or more based on 100 parts by weight of the wastewater layer, because it can exhibit the same or higher organic substance extraction performance as benzene. Further, it is preferable that the amount of the toluene is 40 parts by weight or less based on 100 parts by weight of the wastewater layer, because the recovery rate of the organic matter can be kept high while the cost of recovering and recycling the toluene can be reduced.
[0016]
As a method for extracting organic substances in the wastewater layer with toluene, any method such as a batch method, a continuous method, a countercurrent method, and a Nagata method may be used, but the countercurrent contact method is preferable from the viewpoint of extraction efficiency. Further, the extraction operation can be performed in a temperature range of about 5 to 90 ° C.
Further, a distillation operation is performed to separate and recover toluene from toluene (hereinafter, referred to as organic substance-containing toluene) after extracting and separating organic substances (aniline, MDA, etc.) in the wastewater layer. Toluene contains water and salts in addition to organic matter, which causes clogging in the distillation column and increases the differential pressure, which necessitates periodic cleaning of the column, resulting in increased work efficiency. descend.
[0017]
In the method for recovering organic matter from MDA-containing wastewater of the present invention, in order to suppress the rate of increase in differential pressure due to the clogging and to operate stably for a longer period of time, the distillation column is placed at the upper part (concentration part), preferably at the top part. The toluene and the organic substance are separated from the organic substance-containing toluene by distillation using a distillation apparatus equipped with the ordered packing, and the toluene and the organic substance are recovered and used.
[0018]
Examples of the structured packing to be filled in such a distillation apparatus include a mesh type, a sheet type, a techno pack, a Montz pack, and a Sulzer pack.
In addition, it is preferable to use a tray that is resistant to blockage, such as a valve tray, a sieve tray, or a valve cap tray, directly above the supply part and the supply part of the distillation column. Further, in the recovery section of the distillation column, irregular packing such as Raschig super ring, cascade mini ring, IMTP, etc. may be used.
[0019]
In the present invention, a method for separating and recovering toluene, aniline, and the like by using a distillation column particularly filled with an ordered packing at an upper part, that is, a top part which is a concentration part, preferably a top part from a supply part of an organic substance-containing toluene, preferably a top part. preferable.
[0020]
【Example】
Hereinafter, the present invention will be described more specifically based on examples with reference to FIG. 1, but the present invention is not limited to these examples.
[0021]
Embodiment 1
The MDA-containing reaction mixture obtained by contacting aniline, formalin, hydrochloric acid, and water was neutralized with caustic soda, and then separated in a separation tank. The aqueous layer-1 was 695 kg / h, and the oil layer was 555 kg. / H. The obtained oil layer portion was further washed with 200 kg / h warm water, separated into oil and water, and the water layer portion-2 was extracted at a speed of 230 kg / h.
[0022]
The aqueous layer part-1 and the aqueous layer part-2 were mixed to obtain a mixed wastewater (aniline content: 8,500 ppm, MDA content: 2,000 ppm).
This mixed wastewater was subjected to toluene extraction according to the continuous countercurrent contact type extraction step shown in FIG. That is, 925 kg / h of this mixed wastewater ((1) in the figure) was brought into two-stage countercurrent contact with toluene (1a, 1b in the figure) to extract organic substances such as aniline and MDA in the wastewater.
[0023]
In the extraction and separation step, 925 kg / h of mixed wastewater ((1) in the figure) and 211 kg / h of toluene (3 (3) in the figure) separated from the second-stage separation tank (1b in the figure) were used. The mixture was brought into flow contact, and separated into a wastewater layer ((2) in the figure) and a toluene layer ((4) in the figure) in the first-stage separation tank (1a in the figure) set at 60 ° C. The wastewater layer 916 kg / h ((2) in the figure) was brought into countercurrent contact with 209 kg / h of toluene ((5) in the figure), and was placed in a second separation tank (1b in the figure) set at 60 ° C. The liquid was separated into a wastewater layer ((7) in the figure) and a toluene layer ((3) in the figure).
[0024]
220 kg / h of toluene ((4) in the figure) separated in the first-stage extraction / separation tank (1a in the figure) was transferred to a continuous distillation apparatus (2 in the figure) equipped with a regular packing at the top of the distillation column. As a result of toluene distillation, 11 kg / h of organic substances (aniline, MDA, etc.) were obtained. The aniline and MDA in the wastewater were collected and separated by collecting and recycling the organic matter in the aniline removal step.
[0025]
The aniline content in the wastewater after extraction (7 in the figure) was 210 ppm, and MDA was not detected. The toluene content of the wastewater after the extraction was 130 ppm.
[0026]
[Comparative Example 1]
The operation was performed in the same manner as in Example 1 except that 175 kg / h of benzene was used instead of toluene. As a result, the aniline content in the wastewater after extraction (7 in the figure) was 220 ppm, and MDA was not detected. The benzene content in the wastewater after the extraction was 220 ppm.
[0027]
【The invention's effect】
According to the present invention, since benzene is not used as an extractant, the load on the environment is small, and the extraction performance of organic substances from a wastewater layer equal to or more than benzene can be ensured. Organic matter remaining in the inside can be efficiently recovered by a method with a small load on the environment. Furthermore, since the residual amount of the extraction solvent in the wastewater can be kept low, the wastewater treatment can be performed more easily.
[0028]
Further, according to the present invention, by using a distillation apparatus provided with a structured packing at the top of the distillation tower, from the toluene after extracting and separating the organic matter in the wastewater layer, the toluene and the organic matter are separated by distillation with high working efficiency. In addition, toluene and organic substances can be efficiently recovered and used.
[Brief description of the drawings]
FIG. 1 is an extraction process diagram of a continuous countercurrent contact method.
[Explanation of symbols]
1a, 1b: Extraction separation tank 2: Distillation column equipped with ordered packing
Claims (2)
該廃水層100重量部に対してトルエンを10〜40重量部の量で用いて、該廃水層をトルエン抽出することにより、廃水層に残存する有機物をトルエンとともに分離することを特徴とするメチレン架橋ポリアリールポリアミン含有廃水からの有機物の回収方法。After neutralizing a methylene-crosslinked polyarylpolyamine-containing reaction mixture obtained by condensing aniline and formaldehyde in the presence of an acid catalyst with an aqueous alkali solution, separating an oil layer and a wastewater layer,
Methylene crosslinking characterized by separating organic substances remaining in the wastewater layer together with toluene by extracting the wastewater layer with toluene by using toluene in an amount of 10 to 40 parts by weight based on 100 parts by weight of the wastewater layer. A method for recovering organic matter from polyarylpolyamine-containing wastewater.
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