JPH08150389A - Treatment method of waste liquid containing ethylenediamine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for treating ethylenediamine-containing waste liquid, which can recover useful ethylenediamine from the ethylenediamine-containing waste liquid, effectively use resources, and lead to environmental measures. An ethylenediamine-containing waste liquid for obtaining an ethylenediamine solution by contacting an ethylenediamine hydrochloride solution containing a silane coupling agent and / or a titanium coupling agent with activated carbon to adsorb and remove the silane coupling agent and / or the titanium coupling agent Processing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a useful ethylenediamine by treating an ethylenediamine hydrochloride solution containing a silane coupling agent and / or a titanium coupling agent, that is, an ethylenediamine-containing waste liquid with a simple operation and economically. The method of making a solution of A specific example of the ethylenediamine-containing waste liquid is a waste liquid produced as a by-product when a silane coupling agent or a titanium coupling agent is produced using ethylenediamine.

[0002]

2. Description of the Prior Art Silane coupling agents are produced by reacting chloroalkylalkoxysilanes with ethylenediamine.
Further, the titanium coupling agent is generally produced by the reaction of chloroalkylalkoxy titanium and ethylenediamine. At this time, hydrochloric acid produced as a by-product reacts with excess ethylenediamine to form its hydrochloride.

Since the rate of the reaction decreases as the amount of free ethylenediamine decreases, the reaction is usually carried out using a sufficient amount of ethylenediamine in which the free ethylenediamine remains. Then, the generated silane coupling agent or titanium coupling agent is separated by means such as phase separation.
Therefore, when a silane coupling agent or a titanium coupling agent is produced using ethylenediamine, a hydrochloride solution of ethylenediamine in which the coupling agent is dissolved in a saturated amount or more is by-produced.

Conventionally, there has been no method for treating the ethylenediamine hydrochloride solution, that is, a waste solution containing ethylenediamine, and it has been a standard method to incinerate it as waste.

[0005]

However, the conventional method not only treats useful ethylenediamine as a worthless substance, but also has various problems in terms of generation of NOX and hydrochloric acid gas during incineration and incineration cost. Was there.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for treating ethylenediamine-containing waste liquid, which can recover useful ethylenediamine from the ethylenediamine-containing waste liquid, effectively utilize resources, and lead to environmental measures. Is to provide.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a treatment method of an ethylenediamine-containing waste liquid in order to solve the problems of the conventional method, and as a result, almost completely contacted the ethylenediamine-containing waste liquid with activated carbon. It was found that the silane coupling agent and / or the titanium coupling agent can be removed, and an available ethylenediamine solution can be obtained, and the present invention has been completed.

That is, the present invention is a silane coupling agent and / or
Alternatively, an ethylenediamine hydrochloride solution containing a titanium coupling agent is brought into contact with activated carbon to adsorb and remove the silane coupling agent and / or the titanium coupling agent to obtain an ethylenediamine solution. is there.

The present invention will be described in more detail below.

The silane coupling agent or titanium coupling agent in the present invention is usually produced by reacting a chloroalkylalkoxysilane with ethylenediamine and a latter by reacting a chloroalkylalkoxytitanium with ethylenediamine, and is not particularly limited. .

Specific examples include N- (2-aminoethyl) aminomethyltrimethoxysilane, N- (2-aminoethyl) aminomethylbenzyloxydimethylsilane and N- (2-aminoethyl) -3-aminopropyl. Trimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltris (2-ethylhexoxy) silane, (N- (2-aminoethyl ) Aminomethyl) phenethyltrimethoxysilane, isopropyl tri (N-aminoethyl-aminoethyl) titanate and the like.

During the production of these silane coupling agents or titanium coupling agents, hydrochloric acid is by-produced and reacts with excess ethylenediamine to form its hydrochloride. In addition, the rate of the reaction decreases as the amount of free ethylenediamine decreases, so the reaction is carried out using a sufficient amount of ethylenediamine that leaves free ethylenediamine. Then, the generated silane coupling agent or titanium coupling agent is separated by means such as phase separation. Therefore, when producing a silane coupling agent or a titanium coupling agent using ethylenediamine, a hydrochloride solution of ethylenediamine in which these coupling agents are dissolved, that is,
Waste liquid containing ethylenediamine is by-produced.

The composition of this ethylenediamine-containing waste liquid is
Although not particularly limited, usually the coupling agent 1 to
5 wt%, ethylenediamine hydrochloride 35-80 wt%
(Hydrochloric acid content 13 to 30 wt%), free ethylenediamine 1
It is 5 to 60 wt%, and contains a small amount of water, alcohol and the like. The coupling agent contained may be either a silane coupling agent or a titanium coupling agent, or a mixture thereof.

When the content of the coupling agent is excessive, two liquid phases, that is, the coupling agent phase and the ethylenediamine hydrochloride solution phase in which the coupling agent is dissolved in a saturated amount, may be used. However, considering the operability, it is preferable to perform the treatment in one liquid phase. The concentration of the coupling agent contained in the ethylenediamine hydrochloride solution varies depending on the composition, temperature, etc., and the higher the concentration of ethylenediamine hydrochloride, the higher the water concentration, and the lower the temperature, the lower the concentration. The lower the concentration of the coupling agent, the more it is possible to reduce the amount of the activated carbon at the time of contact with the activated carbon, and it is also possible to add hydrochloric acid to the ethylenediamine-containing waste liquid to neutralize the free ethylenediamine to give ethylenediamine hydrochloride. May be added.

Water has the effect of reducing the viscosity of the ethylenediamine-containing waste liquid, and may be added, but if the water concentration is high, hydrolysis of the coupling agent easily occurs, and the amount of by-products increases,
Moreover, since the treatment liquid amount increases, the addition amount thereof is preferably 50 wt% or less so that an effective thinning effect can be exhibited. Alcohol is
Although derived from a by-product during the synthesis of the coupling agent, it may be added separately for the purpose of reducing the viscosity of the ethylenediamine-containing waste liquid and improving the operability. However, if added in excess, the amount of processing liquid increases, so the amount added is preferably 50 wt% or less at which an effective thinning effect can be exhibited. As the alcohol, lower alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol are preferable because they have a great effect of reducing the viscosity and can be easily separated by distillation from ethylenediamine.

As the activated carbon, commercially available coconut shell charcoal and coal-based coal can be preferably used, but in the present case, coal-based coal is particularly preferable from the viewpoint of effective utilization. As the shape, any of powdered products, granular products, and molded products such as granulated products can be used. When they are contacted in a suspended state, powdery or granular products are preferable, and when they are used on a fixed bed, molded products having high strength are preferable.

The contacting method may be either batch type or fixed bed flow type. The latter is preferable when the utilization rate of activated carbon is increased, the operability is improved, and a large amount of treatment is performed. The batch method is suitable for small-scale treatment, although the activated carbon utilization rate decreases slightly.

The contact temperature is not particularly limited, but is preferably 10 to 100 ° C. When the temperature is 10 ° C. or lower, cooling equipment is required, and the viscosity of the ethylenediamine-containing waste liquid rises to several hundred mPa · s or more, and it is necessary to lengthen the contact time. When the temperature is 100 ° C. or higher, the viscosity can be lowered and the adsorption rate can be increased, and the treatment can be performed in a shorter time, but energy for heating is required. At 10 to 100 ° C., the adsorption rate of the coupling agent is high, the operation is easier, the energy consumption is low, and a suitable contact operation is possible. A more preferable temperature is 20 to 70 ° C., and the above-mentioned effect is further enhanced.

The contact time between the ethylenediamine-containing waste liquid and the activated carbon needs to be changed depending on the temperature, the composition of the ethylenediamine-containing waste liquid, and the contact mode, but the adsorption equilibrium is usually 0.5 to 100 hours. When operating in a fixed bed flow system, superficial velocity (SV): 0.01 to 2 / Hr, liquid linear velocity (L
V): 0.01 to 20 m / Hr can be suitably carried out. If these values are small, the coupling agent removal rate can be increased, but more time is required. Good, but the removal rate of the coupling agent decreases. When the coupling agent is adsorbed, there is no particular change such as large heat generation and solid product formation, and the operability is good. Also, when using the fixed bed flow system,
It is preferable to suppress the mixture of gas such as air into the activated carbon layer as much as possible in order to increase the utilization rate of the activated carbon and the removal rate of the coupling agent. As a pretreatment operation therefor, a deaeration operation such as heating, depressurizing, or ultrasonic treatment of the ethylenediamine-containing waste liquid is suitable. The liquid flow direction can be either upward or downward.

By the above operation, the coupling agent in the ethylenediamine-containing waste liquid can be effectively and efficiently removed. The content of the coupling agent in the ethylenediamine-containing treatment liquid (representing the liquid after adsorbing and removing the silane coupling agent or the titanium coupling agent with activated carbon from the ethylenediamine-containing waste liquid, hereinafter referred to as the ethylenediamine-containing treatment liquid) is 100 ppm. Hereafter, it can be reduced to 10 ppm or less, and the treatment solution containing ethylenediamine can be effectively used. The amount of the coupling agent adsorbed on the activated carbon is 0.1.
More than kg / kg / activated carbon, 0.5 kg / kg / activated carbon or more can be used efficiently. The activated carbon that has adsorbed the coupling agent may be incinerated or may be desorbed and recovered with an organic solvent such as toluene.

The treatment solution containing ethylenediamine after the activated carbon treatment may be effectively utilized as an alkali agent or a reaction agent by utilizing the function of the remaining ethylenediamine, but the ethylenediamine may be isolated by the following method. In that case, it is a preferable method because it can be used in a wider range and the function of ethylenediamine can be further exhibited. That is, (1) an ethylenediamine-containing treatment liquid is distilled to remove impurities having a boiling point lower than that of ethylenediamine such as alcohol, and then an alkali metal hydroxide such as sodium hydroxide is contained in the treatment liquid. A method in which ethylenediamine hydrochloride is neutralized by adding an equivalent amount or more to the hydrochloric acid content, the precipitated hydrochlorides such as sodium chloride are separated and removed, and the solution is distilled to obtain ethylenediamine or an ethylenediamine aqueous solution.

(2) A method of obtaining an ethylenediamine or an ethylenediamine aqueous solution by distilling the hydrochloric acid salt such as sodium chloride precipitated by the method of (1) without separating and removing it.

(3) To the treatment solution containing ethylenediamine, an alkali metal hydroxide such as sodium hydroxide is added in an amount equal to or more than the amount of hydrochloric acid contained in the treatment solution to neutralize and precipitate ethylenediamine hydrochloride. A method of separating / removing a hydrochloride such as sodium chloride, distilling the solution, and fractionally distilling an impurity such as alcohol having a boiling point lower than that of ethylenediamine and ethylenediamine, or the impurity and an ethylenediamine aqueous solution.

(4) The hydrochloride salt such as sodium chloride precipitated by the method of (3) is distilled as it is without separation and removal to obtain impurities such as alcohol and ethylenediamine having a lower boiling point than ethylenediamine, or the impurities and ethylenediamine. Method of fractionating into aqueous solution.

(5) An ethylenediamine phase and an alkali metal such as sodium hydroxide are added to an ethylenediamine-containing treatment liquid in excess of an alkali metal hydroxide such as sodium hydroxide with respect to the hydrochloric acid content of the treatment liquid. This is a method in which two liquid phases of an aqueous solution of hydroxide are formed, and after phase separation, the concentrated ethylenediamine phase is distilled to obtain ethylenediamine or an ethylenediamine aqueous solution.

In the above-mentioned method, the treatment solution containing ethylenediamine may be distilled to remove impurities such as alcohol having a boiling point lower than that of ethylenediamine, and then an alkali metal hydroxide may be added. Alternatively, a hydroxide of an alkali metal may be added to separate and remove precipitated hydrochlorides such as sodium chloride, and then the solution may be distilled.

The alkali metal is not particularly limited, but sodium and potassium hydroxides are preferable in terms of economical use and stable supply in industrial use. Either method is to add a hydroxide of an alkali metal such as sodium hydroxide, to neutralize the hydrochloride, and then to obtain ethylenediamine by distillation, effective and useful to obtain a high-purity ethylenediamine, Can be reused.

[0028]

EXAMPLES The effects of the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Further, the silane coupling agent content and the titanium coupling agent content are Si,
The Ti standard was determined by the ICP analysis method.

Example 1 Waste liquid containing ethylenediamine (composition: ethylenediamine 6
9.0 wt%, hydrochloric acid 25.7 wt%, methanol 2.5
wt%, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (Si standard: 3500 mg / k
g)) 100 g was put in a 250 ml polypropylene Erlenmeyer flask, and then 15 g of commercially available activated carbon (coal-based granular carbon, trade name: Diahope 008) was added, and contact treatment was carried out for 16 hours in a thermostat with a shaker at 40 ° C. Thereafter, the activated carbon was separated and removed by a membrane filter, and the concentration of the silane coupling agent (Si standard) in the filtrate was determined by ICP analysis, and it was 87 mg / kg.

Examples 2 to 10 The same operation as in Example 1 was carried out except that the type and concentration of the coupling agent and the type and amount of the activated carbon in the ethylenediamine-containing waste liquid were changed as shown in Table 1. The results are shown in Table 1. In each case, the coupling agent could be removed efficiently with a small amount of activated carbon. When water or methyl alcohol is used as a diluent for the ethylenediamine-containing waste liquid (Example 7)
In Example 8), the liquid viscosity was lowered, the operability was good, and the adsorption removal rate of the coupling agent was high. The other compositions of the ethylenediamine-containing waste liquid shown in Table 1 excluding the coupling agent are ethylenediamine 71.0 wt%, hydrochloric acid 26.4 wt%, methanol 2.6 wt% and a trace amount of water.

[0031]

[Table 1]

Example 11 A commercially available activated carbon (coal-based granular carbon, trade name: Diahope 008) was placed in a jacketed glass column having an inner diameter of 26 mm.
00 ml was filled (height of packed bed: 1000 mm), and the inside of the jacket was heated with warm water at 55 ° C. A waste liquid containing ethylenediamine (composition: the same as in Example 1) was passed through this activated carbon packed column at a supply rate of 100 ml / Hr. The effluent was sampled at regular intervals, and the Si concentration in the effluent was measured by the ICP analysis method. Effluent volume up to breakthrough is 1
400 ml, and the Si concentration in the effluent at this time was 10
It was less than mg / kg, and the silane coupling agent could be removed efficiently.

Next, 1000 g of the liquid after the activated carbon treatment (composition:
Ethylenediamine 71.0 wt%, hydrochloric acid 26.4 wt
%, Methanol 2.6 wt%) into a 2000 ml round flask equipped with a nitrogen blowing tube and a temperature insertion tube,
Older Shaw distillation column (20 actual stages, 30 mm inner diameter)
71 g of ethylenediamine mixture containing 26 g of low-boiling alcohol (methanol) using a length of 1000 mm)
Was distilled off. 921 g of round flask residue at that time
Was analyzed, the methanol concentration relative to ethylenediamine was 0.01% or less. Then this liquid 800
2000 g equipped with a condenser, a dropping funnel and a stirrer
It was charged in a ml separable flask and maintained at 50 ° C., and 529 g of 48% sodium hydroxide aqueous solution was added by a dropping funnel.
Was added to neutralize the ethylenediamine hydrochloride to precipitate sodium chloride. Then, this slurry was subjected to solid-liquid separation by a centrifugal filtration machine to obtain 1012 g of filtration and 298 g of wet crystals. When the filtrate was analyzed, ethylenediamine was found to be 55
0 g, methanol was 0.01% or less, and no other organic matter was observed.

Example 12 A commercially available activated carbon (coal-based granular carbon, trade name: Kuraray Coal GWH-) was placed in a jacketed glass column having an inner diameter of 26 mm.
C) Fill 500 ml (height of packed bed: 1000 mm),
The inside of the jacket was heated with warm water at 55 ° C. A waste liquid containing ethylenediamine (composition: Example 1
Same as above) was passed through at a feed rate of 50 ml / Hr. The effluent was sampled at regular intervals, and the Si concentration in the effluent was measured by the ICP analysis method. Effluent volume up to breakthrough is 1
It is 700 ml, and the Si concentration in the effluent at this time is 10
It was below mg / kg, and the silane coupling agent could be removed efficiently.

Next, 1000 g of the liquid after the activated carbon treatment (composition:
Ethylenediamine 71.0 wt%, hydrochloric acid 26.4 wt
%, Methanol 2.6 wt%) was charged into a 2000 ml separable flask equipped with a cooling tube, a dropping funnel and a stirrer and maintained at 50 ° C., 609 g of 48% sodium hydroxide aqueous solution was added with the dropping funnel, and ethylenediamine hydrochloride was added to the inside. The mixture was hydrated and sodium chloride was precipitated. Then
1500 g of this slurry was charged into a 2000 ml round flask equipped with a stirrer, a nitrogen blowing tube and a temperature insertion tube,
Older Shaw distillation column (20 actual stages, 30 mm inner diameter)
X length 1000 mm) and water containing 23 g of low boiling alcohol (methanol) and ethylenediamine 168
After removing g by distillation, the mixture was continuously distilled to recover 501 g of an ethylenediamine aqueous solution. The distillation residue in the flask was 822 g. When the ethylenediamine aqueous solution was analyzed by gas chromatography, 325 g of ethylenediamine and the concentration of other organic substances as impurities with respect to ethylenediamine were 0.01% or less, and high-purity ethylenediamine could be recovered and recovered.

Example 13 A commercially available activated carbon (coconut shell granular carbon, trade name: Kuraray Coal GW) 5 was placed in a jacketed glass column having an inner diameter of 26 mm.
00 ml was filled (height of packed bed: 1000 mm), and the inside of the jacket was heated with warm water at 30 ° C. Waste liquid containing ethylenediamine (Si concentration: 1500 m
g / kg, coupling agent type: same as in Example 1) 75
The liquid was passed through at a feed rate of ml / Hr. The effluent was sampled at regular intervals, and the Si concentration in the effluent was measured by the ICP analysis method. The amount of effluent up to the breakthrough point was 1200 ml, and the Si concentration in the effluent at this time was 10 mg / kg or less.

Next, 1000 g of the liquid after the activated carbon treatment (composition:
Ethylenediamine 71.0 wt%, hydrochloric acid 26.4 wt
%, Methanol 2.6 wt%) was charged into a 3000 ml separable flask equipped with a cooling tube, a dropping funnel and a stirrer and maintained at 50 ° C., 1500 g of a 48% aqueous sodium hydroxide solution was added by the dropping funnel, and ethylenediamine was added. The hydrochloride salt was neutralized and the two phases were formed with excess sodium hydroxide. When 1126 g of the upper phase ethylenediamine phase was separated and collected and analyzed by gas chromatography, 683 g of ethylenediamine and 25% of methanol were obtained.
g. Then 1000 g of this ethylenediamine phase
2000 ml equipped with nitrogen blowing tube and temperature insertion tube
A round flask was charged and water containing 22 g of low boiling point alcohol (methanol) and 71 g of ethylenediamine were distilled off using an Oldershaw distillation column (20 actual stages, 30 mm inner diameter x 1000 mm length), and then distilled. Then, 769 g of an ethylenediamine aqueous solution was recovered.
The distillation residue in the flask was 152 g. When the ethylenediamine aqueous solution was analyzed by gas chromatography, the concentration of other organic substances as impurities with respect to ethylenediamine was 0.01% or less, and high-purity ethylenediamine could be recovered and recovered.

Comparative Example 1 1000 g of ethylenediamine-containing waste liquid (composition: the same as in Example 1) which had not been subjected to contact treatment with activated carbon was charged in a 2000 ml separable flask equipped with a cooling tube, a dropping funnel and a stirrer, and 50 ° C. Maintained at 4 ° C by the dropping funnel.
593 g of 8% sodium hydroxide aqueous solution was added to neutralize ethylenediamine hydrochloride to precipitate sodium chloride. Then, this slurry was subjected to solid-liquid separation by a centrifugal filtration machine to obtain 1234 g of the filtration liquid and 337 g of wet crystals. When the filtrate was analyzed, ethylenediamine was 668 g, methanol was 22 g, water was 420 g, and sodium chloride was 95 g.
g, sodium hydroxide 3 g, silane coupling agent 27 g, and other organic substances were not observed.
Next, 1000 g of this filtrate was charged into a 2000 ml round flask equipped with a nitrogen blowing tube (capillary) and a temperature insertion tube, and an Oldershaw distillation column (20 actual stages,
80kP using inner diameter 30mm x length 1000mm)
Under a reduced pressure of a, a low boiling point substance was separated and removed by a distillation operation under the conditions of a reflux ratio: R / D = 10/1 and a liquid temperature in the flask: 115 to 118 ° C., and ethylenediamine was separated and recovered.

First, 102.7 g of an ethylenediamine aqueous solution containing 17.1 g of low-boiling-point methanol and 29.1 g of ethylenediamine as the first fraction was distilled off and then distilled, and the second fraction was diluted with ethylenediamine 32.5.
70.5 g of an ethylenediamine aqueous solution containing g was recovered. Gas chromatographic analysis (capillary column DB-5: inner diameter 0.23 mm × length 30 m, detector: hydrogen flame) of this second fraction revealed that the organic composition in the solution was ethylenediamine 96.4%, methanol 3.3.
% And other impurities 0.3%.

Further distillation was carried out to obtain 204.1 g of an ethylenediamine aqueous solution containing 116.5 g of ethylenediamine as the third fraction, and ethylenediamine 12 as the fourth fraction.
205.7 g of an ethylenediamine aqueous solution containing 7.2 g and about 58 wt% of the filtered and charged filtrate were recovered as a distillate. Gas chromatography analysis of the third and fourth fractions as well as the second fraction revealed that the organic compounds in the solution were ethylenediamine 99.1%, 99.3%, methanol 0.6%, 0.5%, respectively. Other impurities were 0.2%. Also, 409 g of a pale yellowish brown slurry distillation residue was obtained in the flask.

As described above, in the method of neutralizing with sodium hydroxide without performing activated carbon treatment and distilling the produced sodium chloride crystals after separation, methanol and other organic impurities are distilled during the whole process of distillation purification. However, ethylenediamine that could be effectively used was not obtained. These impurities are considered to be the decomposition products of the silane coupling agent due to heat and / or alkali.

[0042]

According to the present invention, the ethylenediamine-containing waste liquid can be effectively and efficiently treated, useful ethylenediamine can be recovered, resources can be effectively used, and environmental measures can be taken. The effects will be listed below.

(1) An industrially useful ethylenediamine treatment liquid substantially free of a coupling agent by treating an ethylenediamine-containing waste liquid containing a silane coupling agent and / or a titanium coupling agent with a simple apparatus and operation. Can be obtained.

(2) The adsorption capacity of the activated carbon for the coupling agent is large, and economical treatment can be realized.

(3) By using an ethylenediamine-containing treatment solution as a post-treatment, adding an alkali metal hydroxide to neutralize the hydrochloride, and then distilling, to obtain a highly pure and high-concentration ethylenediamine or / and ethylenediamine aqueous solution. As a result, the range of use is expanded, and it is industrially effective and useful.

(4) The method of the present invention can be easily carried out as an industrial method.

[0047]

Claims (6)

[Claims] 1. An ethylenediamine characterized in that an ethylenediamine hydrochloride solution containing a silane coupling agent and / or a titanium coupling agent is brought into contact with activated carbon to adsorb and remove the silane coupling agent and / or the titanium coupling agent. Treatment method of contained waste liquid. 2. The treatment solution containing ethylenediamine obtained by the treatment method of claim 1 is distilled to remove impurities having a boiling point lower than that of ethylenediamine, and then the treatment solution contains a hydroxide of an alkali metal. A method for treating an ethylenediamine-containing waste liquid, which comprises adding an equivalent amount or more to a hydrochloric acid component to separate and remove a precipitated hydrochloride, and further distilling the solution to obtain ethylenediamine or an ethylenediamine aqueous solution. 3. The method for treating an ethylenediamine-containing waste liquid according to claim 2, wherein the precipitated hydrochloride is distilled as it is without separation / removal to obtain ethylenediamine or an ethylenediamine aqueous solution. 4. An ethylenediamine-containing treatment liquid obtained by the treatment method according to claim 1 is added with an alkali metal hydroxide in an amount equal to or more than the amount of hydrochloric acid contained in the treatment liquid, and the precipitated hydrochloride is separated and removed. And then distilling the solution to fractionally distill an impurity having a boiling point lower than that of ethylenediamine and ethylenediamine, or an impurity and ethylenediamine aqueous solution, to treat an ethylenediamine-containing waste liquid. 5. The method according to claim 4, wherein the precipitated hydrochloride is distilled as it is without separation / removal, and impurities having a boiling point lower than ethylenediamine and ethylenediamine,
Alternatively, a method for treating an ethylenediamine-containing waste liquid, which comprises fractionating the impurities with an ethylenediamine aqueous solution. 6. An ethylenediamine phase and an alkali metal hydroxide are added to the ethylenediamine-containing treatment liquid obtained by the method of claim 1 in excess of an alkali metal hydroxide with respect to the hydrochloric acid content of the treatment liquid. The method for treating an ethylenediamine-containing waste liquid, comprising the steps of forming two liquid phases of the aqueous solution phase, separating the phases, and distilling the concentrated ethylenediamine phase to obtain ethylenediamine or an ethylenediamine aqueous solution.