JPS61114744A - Treatment of ion exchange resin regeneration solution containing copper - Google Patents

Abstract

PURPOSE:To economically recover copper as copper hydroxide at high yield, by passing air through a cation exchange resin regenerating solution containing copper under an acidic condition of pH3 or less before adjusting the pH value thereof to 10.5-13. CONSTITUTION:A cation exchange resin regenerating solution containing copper is brought to an acidic condition of pH3 or less and, pref., about 0.2-1 volume of air, further pref., about 0.4-0.5 volume of air is passed through the treated solution, pref., for about 2-36hr, further pref., for about 4-30hr. Subsequently, the pH of the treated solution is adjusted to 10.5-13, pref., to about 11-12 to form a precipitate which is, in turn, subjected to filtering treatment. By this method, the concn. of the copper ion in the filtrate is reduced to about 10ppm or less and copper becomes recoverable as copper hydroxide. The cation exchange resin in this method can be selected from a general strong acidic cation exchange resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing acrylamide, and more particularly to a method for treating a recycled cation exchange resin solution containing copper, which is useful for resource recovery and pollution prevention.

(Prior art and its problems) The acrylamide aqueous solution obtained by reacting acrylonitrile with water in the presence of a metallic copper catalyst such as Raney copper, reduced copper, or Ullmann copper is composed of (1) unreacted acrylonitrile; (2) Metal ions such as copper and copper complex ions eluted from the catalyst component; (3) Impurities contained in the raw material acrylonitrile; and (4) side reaction products such as organic acids. Among these, unreacted acrylonitrile (IJ) can be easily removed by conventional methods such as distillation, but other substances are purified by treatment with a strongly acidic cation exchange resin and then with a weakly basic anion exchange resin. ℃・ru (for example, Special Publication No. 52-91819). In this case, the strongly acidic cation exchange resin usually adsorbs metal ions, copper forming copper complex ions, cationic impurities, side reaction products, etc., and can be used repeatedly by regenerating with acid. Ru. When a strongly acidic cation exchange resin is regenerated, the method of adding alkali and separating it as hydroxide steel, which is generally adopted as a method for treating the copper eluted into the regenerating solution, is not suitable for the production of acrylamide as described above. It is difficult to apply copper hydroxide because the precipitation of copper hydroxide is insufficient due to the influence of other impurities.

Another method is to add a metal that has a higher ionization tendency than copper ions and precipitate the copper ions as metallic copper, but in this method, some metals dissolve as metallic ions by precipitating as metallic copper. This has the disadvantage that it must be removed again to remove the copper, and since the metal required for metallic copper precipitation is often expensive, it is also not economical to apply it to the regenerating solution.

(Means for Solving the Problems) The present inventors have discovered that there are no drawbacks seen in such prior art, and
As a result of extensive research to find a simple and economical treatment method, we found that copper hydroxide was sufficiently precipitated by aerating air into the treatment solution under acidic conditions with a pH of 3 or less and then neutralizing it. The present invention has been achieved by discovering that the copper content in the P solution can be significantly reduced by separating this into r.

That is, the present invention provides a method for producing acrylamide in which acrylamide is synthesized using an aqueous phase of acrylonitrile and a cation exchange resin is used in the purification step, in which the cation exchange resin regenerated solution containing copper is aerated with air under acidic conditions with a pH of 3 or less. This is a method for treating a copper-containing cation exchange resin regenerated solution, which comprises adjusting the pH to 10.5 to 13.

Next, the present invention will be explained. Since the method of producing acrylamide using an aqueous phase of acrylonitrile uses a copper-based catalyst, purification using a cation exchange resin is essential to remove copper ions derived from the catalyst. The regenerated solution regenerated with mineral acids usually contains copper ions and other substances as described above.

In the present invention, in order to treat the copper in these regenerating solutions, air is preferably added at a volume of 0.2 to 1 volume per minute to the processing solution, for example, for 2 to 36 hours, under acidic conditions of p'H3 or less. More preferably, after aerating 0.4 to 0.5 times the volume of air for 4 to 20 hours, the processing solution is adjusted to pH 10.5 to 10.5.
13, preferably 11 to 12.5, and then precipitates and separates P.

When using the above method, the copper ion concentration in the P solution is 1
0 ppm or less, and copper can be recovered as copper hydroxide. At this time, when aeration is performed under conditions where the pH exceeds 3, it is difficult to reduce the copper ion concentration in the P solution to 10 ppm or less after precipitation with an alkali and f separation. The regenerated liquid is usually obtained as an acidic liquid with a pH of 1 or less, and it is preferable to aerate air as it is.
This may be done after adjusting the value to an appropriate value of 3 or less.

The cation exchange resin employed in the method of the present invention can be selected from general strong acid cation exchange resins made by sulfonating a styrene-divinylbenzene copolymer, such as Revachit 5P-112 (a product manufactured by Bayer AG). name), Amberlite IR-120B (manufactured by Rohm and Haas, trade name), and the like. The alkali for neutralization can be selected from common inorganic alkalis, such as sodium hydroxide, calcium hydroxide, and the like. If the pH of the intermediate phase is less than 10.5 or greater than 13, the concentration of copper ions in the f liquid will exceed 10 ppm, which is not preferable. Air ventilation time is generally 2
Less than 20 hours tends to be insufficient, and more than 20 hours is not economical. Moreover, other oxygen-containing gases may be used instead of air. Precipitation of hydroxide steel
When separating, it is more effective to add a polymer flocculant,
The polymer flocculant can be selected from common polymer flocculants that are polymers made of acrylamide and sodium acrylate.

(Operation and effect of the invention) The advantages brought about by the invention are as follows.

(1) By aerating air under acidic conditions with a pH of 3 or less, copper can be treated by a neutralization precipitation method, and can be recovered as copper hydroxide in a high yield and economically.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 6 Preliminarily deoxygenated acrylic acid nitrile and deoxygenated pure water were fed to a suspended bed reactor using Raney copper as a catalyst for consecutive days, and the resulting reaction liquid was subjected to catalytic filtration. The mixture was filtered through a vacuum distiller, and almost all of the unreacted acrylonitrile and a portion of the water were distilled off through a vacuum distiller to obtain a 43% acrylamide aqueous solution as the distiller's bottoms. This water bath solution was treated at room temperature and pressure by blowing air into it, and then passed through a column filled with H-type cation exchange resin 5P-112 (manufactured by Bayer AG). The pH of the acrylamide aqueous solution after flowing is 3.5.
At this point, the liquid passage was terminated, and the cation exchange resin was washed with water, and then regenerated with 2N hydrochloric acid.

The obtained regenerating solution containing 0.5% copper ions was aerated with air at a rate of 0.4 times the volume per minute of the treated solution for 18 hours, and then 20%
The predetermined pH was adjusted to a predetermined pH with sodium hydroxide, and the mixture was stirred for 1 hour to form a precipitate. A polymer flocculant, trade name A-110 (manufactured by Mitsui Cyanamid Co., Ltd.) was added to separate the P. Table 1 shows the results of measuring the copper ion concentration in the f solution while varying the pH conditions at this time.

Examples 7 to 13 After conducting experiments in the same manner as in Examples 1 to 6 except that the cation exchange resin was replaced with IR-120B (manufactured by Rohm and Haas),
The cation exchange resin was regenerated with 2N hydrochloric acid, and the resulting regeneration solution containing 0.5% copper ions was added to the treatment solution at a rate of 0.5% per minute.
After aerating 4 times the volume of air for 2 to 200 hours, 20
% hydroxide) Adjust the pH to 11.5 with IJum and stir for 1 hour to form a precipitate.
(manufactured by Mitsui Cyanamid Co., Ltd.) was added and separated. Table 2 shows the results of measuring the copper ion concentration in the f liquid at each ventilation time.

Comparative Example 1 In Examples 1 to 6, only the neutralization pH was changed to 10.0, and the f liquid steel concentration was 31.8 ppm.

Comparative Example 2 In Examples 1 to 6, except that only the neutralization pH was changed to 13.5, the f-liquid copper concentration was 21.8 ppm.

Comparative Example 3 The regenerated liquid obtained in Examples 7 to 13 was once adjusted to pH 4 with sodium hydroxide, and then the treated liquid was adjusted to pH 0.4 per minute.
When twice the volume of air was passed through the steel for 18 hours and the steel was treated in the same manner, the f-liquid steel concentration was 11Q, 2 ppm.

Reference Example 1 In Examples 7 to 13 in which only the aeration time was changed to 1 hour, the F liquid copper concentration was 32.8 ppm.

Claims (1)

[Claims] In a method for producing acrylamide in which acrylamide is synthesized by hydration of acrylonitrile and a cation exchange resin is used in the purification process, the cation exchange resin regenerated solution containing copper is aerated with air under acidic conditions of pH 3 or less, and then the pH
A method for treating a cation exchange resin regenerated liquid containing copper, the method comprising adjusting the value to 10.5 to 13.