JPS5830384A - Method for recovering amines in waste water in high concentration - Google Patents

Abstract

PURPOSE:To recover amines in high concn. of >=25% by regenerating the active carbon which is brought into contact with waste water contg. water soluble amines with sulfuric acid, and recoveing the water/amines phase separated by concentrating, neutralizing with alkali and salting out of the regenerating liquid. CONSTITUTION:Waste water contg. water soluble amines such as alkyl tertiary amines, tetra-substd. polymethylene diamines or the like is passed through a filter and is brought into contact with active carbon as it is. Ordinary granular active carbon is used here and in a special case such as batch operation, the use of granular active carbon is equally well. Sulfuric acid is added to the active carbon adsorbed with amines to regenerate the active carbon. The regenerating liquid is stored in a tank or the like, and sulfuric acid is added to the active carbon by the second contact with said regenrating liquid. The above-mentioned operations are repeated. The concd. regenerating liquid is neutralized with alkali and is salted out, whereby the liquid is separated to the two phases; a water/ amines phase, and a water/alkali sulfate phase; thereafter, the water/amines phase is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering highly concentrated amines from wastewater containing amines. More specifically, the present invention relates to a method for recovering highly concentrated amines from wastewater containing amines. , relates to a method for recovering high-concentration amines by concentrating, neutralizing, and salting out a regenerated solution.

In general, amines are widely used as raw materials for various surfactants, raw materials for synthetic chemicals, intermediates, catalyst aids, epoxy resin JIi-r curing agents, urethane catalysts, and the like. Of these amines, water-soluble amines will need to be treated in some way if they are found 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 for wastewater treatment. In other words, a method in which various coagulants or the like are added to an amine compound and floated under pressure is hardly effective because the amine compound is unlikely to form water-insoluble matter.

It is generally known that amine compounds are difficult to remove even in small-scale biochemical treatments, and although it is a special wastewater of organic synthesis, it has been shown that it does not decompose at all, according to Japanese Patent Application Laid-open No. 115556/1983. There is.

Therefore, it is necessary to consider other methods.
No. 556 discloses a method of recovering amines by treating with activated carbon and adding organic and inorganic acids to the activated carbon.

However, although amines come out in the form of salts when acids are added, the salts have relatively low concentrations, and if they are discharged as they are, CO
The D value is high, there is no indication as to what to do with this salt, the treatment technology is still incomplete, and there are many problems in industrially adopting this method.

Under these circumstances, the present inventors have conducted intensive studies to develop a method for recovering water-soluble amines at high concentrations, and have arrived at the present invention.

That is, the present invention includes a step of bringing wastewater containing water-soluble amines into contact with activated carbon, a step of generating -F+ with sulfuric acid on the activated carbon adsorbing the amines, a step of condensing by repeatedly using a regenerated liquid, Neutralize the concentrated regenerated liquid with alkali and salt out L2
This is a method for recovering amines in wastewater at a high concentration, which comprises a step of separating into two phases, a water/amine normal phase and a water/alkaline sulfuric acid phase, and a step of recovering the water/amine normal phase.

By the method of the present invention, amines that are dissolved in wastewater at a low concentration of several tens to several thousand ppm can be recovered at a high concentration of at least 25%, and this can be further purified by distillation etc. It is extremely effective as a technology for recycling expensive amine compounds, and has extremely large industrial value.

The amines to be used in treatment 1 in the present invention are not particularly limited as long as they are water-soluble amines, but include alkyl 6th class amines, tetra-substituted polymethyl/fujiamines, substituted, 1-seriethylene polyamines, triethylene diamines, and other alkyl secondary amines.

Examples of these amine compounds include triethylamine, diethylmethylamine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethylbutanediamine, tetraethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltriethylenetetramine, triethylenediamine, diethylamine, dipropylamine, etc. can be mentioned.

Wastewater containing such water-soluble amines is usually
Since it is alkaline, it is passed through a filter and brought into contact with the activated carbon. Activated carbon is usually used in granular form, but in special cases such as patch operations, powdered form may also be used. Any type of activated carbon can be used, although its adsorption capacity may vary depending on the raw material source. The contact operation can be carried out in a batch or continuous manner, but the continuous method is more efficient. Continuous type W, combined fine speed Wld usually 1 to 15
This is done in the 0 range of about 1r (m/)1r, but it may be faster or slower depending on the %I ratio. Chemical 1. If the length of the sum adsorption zone increases, the efficiency is not good.

There is no particular limit to the contact temperature, but it is usually in the range of 10 to 60''.If the temperature is high, the efficiency of absorbing water tends to deteriorate.

Such contacting operations purify the treated water and allow it to be drained, especially as long as it is free of other harmful substances.

Next, the process of the present invention in which all amines are adsorbed and the activated carbon is regenerated with sulfuric acid will be described. The acid used to completely regenerate activated carbon in this step must be sulfuric acid. Acids other than sulfuric acid, such as hydrochloric acid and nitric acid, will undergo salting out in the later process17.
In the process of dividing the amine into two phases, the two phases do not separate, making it impossible to recover all of the amine at high concentrations. Sulfuric acid is added to activated carbon that has absorbed amines to saturation to regenerate the activated carbon. In this case, the amount of sulfuric acid used is preferably 117 or more, or 1.5 times the amount of M1 or more of the adsorbed amines. The higher the temperature of the sulfuric acid to be added, the higher the concentration of amine sulfate in the regenerated solution because excess moisture will not be added, so it is better to adjust the temperature, but the appropriate concentration should be determined depending on the material of the adsorption tower, the strength of the granular activated carbon, etc. It is better to remove all the water in the adsorption column before the adsorption is saturated and sulfuric acid is added.

Next, the process of reusing and concentrating the regenerated liquid will be described. In this process, the regeneration liquid that came out in the previous process is stored in a suitable vortex tank, etc., and when the next time it is necessary to regenerate activated carbon, the regeneration liquid comes into contact with the activated carbon for the second time and is adsorbed by the activated carbon. Add only sulfuric acid in an amount equivalent to or more than the amount of amines, or more than 1.5 times the amount of sulfuric acid, and regenerate the activated carbon that has been saturated and adsorbed with this liquid (7. This is a process that is repeated. Repeat several times. Whether it is necessary at least reaches a concentration necessary for the concentrated regenerated liquid to be separated into two phases in the next step, and the two-phase separation conditions also depend on the concentration of the alkali used in the next step.

Next, a process will be described in which the concentrated regenerated liquid is neutralized with an alkali, salted out, and separated into two phases: a water/amine normal phase and a water/alkali sulfuric acid base phase. This step is a step in which all of the alkali 11 is added to the ladle solution containing the amine sulfate at a certain concentration in the previous step. Examples of the alkali include caustic soda, sumo wrestler ikali, 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.

If alkali is added to the concentrated regenerated liquid in small amounts with amines, it will generate a little heat, but the upper phase will contain water and amine, and the lower phase will contain water and alkali sulfate. minute 1
A in J] 1 separation. This neutralization point ld:pt1 is detected. Therefore, by removing the upper phase, an aqueous amine solution containing bacteria can be obtained. Under conditions for phase separation, the amine concentration will be at least 25%.

Hereinafter, the method of the present invention will be specifically explained with reference to Examples.

Example 1 Water containing 500 ppm of tetramethylpropanediamine was passed through a column with an inner diameter of 30 mm packed with 150 g of coconut shell activated carbon at a linear velocity of 3 m/hr, and the total amount of tetramethylpropanediamine in the effluent was passed through. Continuing the liquid, saturated adsorption activated carbon was obtained. This saturated adsorbent activated carbon Q was regenerated from 300 ml of regenerating solution containing 23 g of sulfuric acid, 7'j.

Next, water newly containing amine was passed through the regenerated activated carbon to obtain saturated adsorbent activated carbon, 25 g of 98-thiosulfuric acid was newly added to the regenerated liquid, and the saturated adsorbed activated carbon was regenerated with this liquid.

This operation was repeated 45 times (L2) to obtain a concentrated regenerated liquid.

When this regenerated liquid "ff" was neutralized with a 50% caustic soda aqueous solution, the regenerated liquid phase-separated into an upper phase containing water and tetramethylpropanediamine and a lower phase containing water and sodium sulfate within 1 minute after neutralization. Decantation The concentration of tetramethylpropanediamine in the upper phase taken out was 62%.

Example 2 When water containing 500 ppm of tetramethylethylenediamine was treated in the same manner as in Example 1, the treated water was 191
The concentration of teleramethylethylenediamine at t is I Q p
It was below pm. First, phase separation occurs after neutralization, and the δ' degree of tetramethylethylenediamine in the upper phase is 26%.
Met.

Example 6 When water containing 400 ppm of pentamethyldiethylene/nitria-S was treated in the same manner as in Example 1, the concentration of pentamethyldiethylene (IJ) amine in the treated water 247-j was 10 ppm or less. -P, phase separation occurred after neutralization, and the concentration of pentamethyldiethylenetriamine in the two phases was 28.

Comparative Example 1 When the regenerated liquid used only once in Example 1 was neutralized in the same manner, there was no two-phase separation in the ZeJ raw liquid.

t;#, the concentration of tetramethylpropanediamine in the medium fl regenerant was 2% or less.

Comparative Example 2 In Example 1, when hydrochloric acid was used as the regenerant and (-), the regenerated solution after neutralization was separated into two phases [7]. concentration of 1 liter
-t2% or less.

Comparative Example 6 When nitric acid was used as the regenerating agent in Example 1, the regenerated liquid after neutralization did not undergo two-phase separation. The concentration of tetramethylpropanediamine in the regenerated solution after neutralization was less than 2%.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. A process in which wastewater containing water-soluble amines is brought into contact with activated carbon, a process in which activated carbon that has adsorbed amines is regenerated with sulfuric acid, a process in which the regenerated liquid is repeatedly used to concentrate it, and a process in which the concentrated regenerated liquid is neutralized with an alkali. A method for recovering high concentrations of amines in wastewater, which consists of a step of separating into two phases, a water/amine normal phase and a water/alkali sulfate phase by salting out, and a step of recovering the water/amine normal phase.