JPH0230315B2 - AMINRUIOFUKUMUHAISUINOSHORIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater containing amines, and more specifically, the present invention relates to a method for treating wastewater containing amines, and more specifically, the present invention relates to a method for treating wastewater containing amines. This invention relates to a method for treating wastewater with high concentrations of amines by regenerating resin with an inorganic acid and neutralizing the regenerated liquid.

In general, amines are widely used as raw materials for various surfactants, raw materials for synthetic chemicals, intermediates, catalyst aids, epoxy resin curing agents, urethane catalysts, and the like. Of these amines, water-soluble amines need to be treated in some way if they are contained in trace amounts in wastewater, depending on usage conditions. However, water-soluble amines are difficult to remove by solid-liquid separation, which is a common method of wastewater treatment. In other words, the methods of flocculation separation by adding various flocculants to amine compounds, sedimentation separation methods, and flotation separation methods are almost ineffective because amine compounds are difficult to form water-insoluble substances.

It is also known that amine compounds are generally difficult to remove with biological treatment.

The object of the present invention is to effectively treat such water-soluble amines.

The present invention consists of a step of bringing wastewater containing water-soluble amines into contact with a weakly acidic ion exchange resin, a step of regenerating the weakly acidic ion exchange resin that has adsorbed amines with an inorganic acid, and a step of neutralizing the regenerated liquid with an alkali. A method for effectively treating wastewater containing water-soluble amines, a step of bringing the wastewater containing water-soluble amines into contact with a weakly acidic ion exchange resin, a step of regenerating the ion exchange resin that has adsorbed amines with sulfuric acid, and regeneration. The process of repeatedly using and concentrating the liquid, neutralizing the concentrated regenerated liquid with an alkali, salting out, and forming a water/amine phase and a water/
This is a method for treating wastewater containing amines, which comprises a step of separating into two phases, an alkali sulfate phase, and a step of recovering a water/amine phase.

By the method of the present invention, tens to thousands of ppm can be produced in wastewater.
At least amines that are soluble at low concentrations such as
The amine can be purified to 10 ppm or less, and the amine can be recovered at a high concentration of 5% or more.

The recovered liquid can be subjected to subsequent industrial processing,
The problem of recycled waste liquid, which is a drawback of wastewater treatment using ion exchange resins, has also been solved.

The amines that can be treated in the present invention are not particularly limited as long as they are water-soluble amines, but include alkyl tertiary amines, tetra-substituted polymethylene diamines, substituted polyethylene polyamines, triethylene diamines, and other alkyl amines. Secondary amines, etc. Examples of these amine compounds include triethylamine, diethylmethylamine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethylbutanediamine, tetraethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltriethylenetetramine, triethylenediamine, diethylamine, and dipropylamine. etc.

Such wastewater containing water-soluble amines is usually alkaline as it is, and if suspended solids are removed through a filter, it can be brought into contact with a weakly acidic ion exchange resin as it is. Any type of weak acid type ion exchange resin can be used, although there are some differences in exchange capacity, physical strength, etc. depending on the type. The contact method may be a batch method or a column method using up-flow or down-flow. In the case of a downflow column method, the linear velocity of liquid flow is usually about 10 to 100 m/hr, but
It may be faster or slower than this depending on the situation. However, as the speed increases, the length of the adsorption zone becomes longer, which is not good in terms of efficiency. The contact temperature is not particularly limited as long as it is below the maximum operating temperature of each of the various weakly acidic ion exchange resins.

Through this contact operation, the treated water is purified and can be discharged as is unless it contains other harmful substances.

It is preferable that normal backwashing is performed after this contacting operation, and the backwash water is drained.

Next, the process of regenerating the weak acid type ion exchange resin that has adsorbed amines in the above contact process according to the method of the present invention will be described. An inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid is added to the weak acid type ion exchange resin that has adsorbed amines to regenerate it. At this time, the amount of inorganic acid contacted is equal to or more than the equivalent of the adsorbed amine, preferably 1.5 times or more. The higher the concentration of the inorganic acid to be added, the higher the concentration of amines in the regenerated liquid because excess water will not be added, so it is preferable, but the material of the resin packed column,
An appropriate concentration may be determined based on the acid resistance of various weak acid type ion exchange resins.

Next, the process of neutralizing the regeneration liquid will be described.
Since amines exist as inorganic acid salts in the regeneration liquid obtained from the regeneration process, in order to obtain free amines, the regeneration liquid must be treated with an alkali stronger than the amine, such as caustic soda, caustic potash, and their aqueous solutions. need to be neutralized. The required amount of alkali may be added in an amount equivalent to the amine contained in the regenerating solution, and this neutralization point can be detected by pH.

In the second invention of the present invention, the following method is used.
Amines can be recovered at high concentrations of 25% or more.

Contact between the water-soluble amine and the weakly acidic ion exchange resin is carried out in the same manner as described above.

After this contacting operation, normal backwashing is performed, and the backwash water is extracted to prevent water from increasing in the regenerating liquid.

Next, a process of recovering and regenerating amines at a high concentration of 25% or more using a weakly acidic ion exchange resin that has adsorbed amines in the above adsorption process will be described. The regenerant uses sulfuric acid to cause phase separation in the subsequent neutralization step. Phase separation does not occur with acids other than sulfuric acid, such as hydrochloric acid and nitric acid. Regeneration is carried out by bringing the weakly acidic ion exchange resin that has saturatedly adsorbed amines into contact with sulfuric acid in an amount equivalent to or more, preferably 1.5 times or more, the amount of the adsorbed amines. The higher the concentration of sulfuric acid to be added, the higher the concentration of amines in the regenerated liquid because excess water will not be added, so it is preferable. All you have to do is determine.

Next, the process of concentrating the regenerated liquid by repeatedly using the regenerated liquid will be described. In this process, the regenerating liquid that came out in the previous process is stored in a suitable tank, etc., and when the weak acid type ion exchange resin needs to be regenerated, the regenerating liquid is contacted for a second time to regenerate the weak acid type ion exchange resin. This is a step in which only sulfuric acid is added in an amount equal to or more than the equivalent of the amines adsorbed on the ion exchange resin, preferably more than 1.5 times the equivalent, and the weak acid type ion exchange resin that has adsorbed the amines is regenerated with this liquid, and this process is repeated. The number of times it is necessary to repeat the process is at least until the concentration required for two-phase separation in the next step is reached, and the conditions for this two-phase separation also depend on the concentration of the alkali used.

Next, the process of neutralizing the concentrated regenerated liquid with an alkali, salting out, and separating it into two phases, a water/amine phase and a water/alkali sulfate phase, will be described. This step is a step in which an alkali is added to the regeneration solution containing amine sulfate at a certain concentration or higher in the previous step. Examples of the alkali include caustic soda, caustic potash, and aqueous solutions thereof. In the present invention, there is no particular restriction as long as the alkali is stronger than the amines to be treated, but caustic soda and its aqueous solution are preferred.
When alkali is added to an amount equivalent to the amine contained in the concentrated regenerated liquid, it generates some heat, but the phase separates within a few minutes into a phase containing water and amine in the upper phase and a phase containing water and alkali sulfate in the lower phase. do. This neutralization point is detected by PH.

Therefore, by removing the upper phase, a highly concentrated amine aqueous solution can be obtained. Under conditions for phase separation, the amine concentration will be at least 25%.

The method of the present invention will be specifically explained below with reference to Examples.

Example 1 Wastewater containing 500 ppm of tetramethylpropanediamine was treated with commercially available H-type weak acid type ion exchange resin 200
A linear velocity of 12 m/ml was applied to a 18.5 mm inner diameter column filled with
When the amount of tetramethylpropanediamine in the effluent water was determined, it was less than 5 ppm up to 34 hours. Further, the solution was continued to pass through, and a weak acid type ion exchange resin with saturated adsorption was obtained. After backwashing and draining this saturated adsorption weak acid type ion exchange resin, it was regenerated with 300 ml of regenerating solution containing 48 g of sulfuric acid. This regeneration liquid
When neutralized with a 50% caustic soda aqueous solution, the concentration of tetramethylpropanediamine in the regenerated solution was 6.6.
It was %.

Example 2 The weak acid type ion exchange resin regenerated in Example 1 was saturated with amine again, and this was mixed with the regenerated liquid prepared by newly adding 48 g of 98% concentrated sulfuric acid to the regenerated liquid of Example 1. Replayed. This operation was repeated four times to obtain a concentrated regenerated liquid. When this concentrated regenerated liquid was neutralized with a 50% caustic soda aqueous solution, the concentrated regenerated liquid separated into an upper phase containing water and tetramethylpropanediamine and a lower phase containing water and sodium sulfate within 1 minute after neutralization. The concentration of tetramethylpropanediamine in the upper phase taken out by decantation was 34%.

Example 3 The treatment was carried out in the same manner as in Example 1, except that wastewater containing tetramethylethylenediamine was used. As a result, the concentration of tetramethylethylenediamine in the effluent was below 3ppm. Further, the concentration of tetramethylethylenediamine in the regenerated liquid after neutralization was 6.1%.
Further, as in Example 2, the regeneration liquid was used four times, and the concentration of tetramethylethylenediamine in the upper phase obtained by phase separation was 28%.

Example 4 The treatment was carried out in the same manner as in Example 1 except that wastewater containing pentamethyldiethylenetriamine was used as the amine. As a result, the concentration of pentamethyldiethylenetriamine in the effluent was up to 28
It was less than 1 ppm. In addition, the concentration of pentamethyldiethylenetriamine in the regenerated solution after neutralization is 7%.
It was hot. Further, as in Example 2, the regeneration solution was used four times, and the concentration of pentamethyldiethylenetriamine in the upper phase obtained by phase separation was 30%.

Comparative Example 1 Various aluminum salt type flocculants, iron salt type flocculants, and organic polymer flocculants were added to water containing 200 ppm of tetramethylpropanediamine, and flocculation separation was attempted under appropriate conditions, but It was found that the concentration of tetramethylpropanediamine was 170 to 200 ppm, making it difficult to separate the aggregates.

Comparative Example 2 Treatment was carried out in the same manner as in Example 1 except that a strong acid type ion exchange resin was used instead of a weak acid type ion exchange resin, and the concentration of tetramethylpropanediamine in the effluent was 1 ppm after passing 16 times. As a result, only 60% of the adsorbed tetramethylpropanediamine was regenerated, and the concentration of tetramethylpropanediamine in the regenerated liquid after neutralization was 1.8%.

Claims (1)

[Claims] 1. A step of bringing wastewater containing water-soluble amines into contact with a weakly acidic ion exchange resin, a step of regenerating the weakly acidic ion exchange resin that has adsorbed the amines with an inorganic acid, and neutralizing the regenerated liquid with an alkali. A method for treating wastewater containing amines. 2 A process in which wastewater containing water-soluble amines is brought into contact with a weakly acidic ion exchange resin, a process in which the weakly acidic ion exchange resin that has adsorbed amines is regenerated with sulfuric acid, a process in which the regenerated liquid is repeatedly used and concentrated, a concentrated regenerated liquid A method for treating wastewater containing amines, which comprises the steps of neutralizing with an alkali, salting out and separating into two phases, a water/amine phase and a water/alkali sulfate phase, and recovering the water/amine phase.