JPS5946252B2 - Manufacturing method of heavy metal ion adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heavy metal ion adsorbent having a selective adsorption ability for heavy metal ions dissolved in water as cations and complex ions.

Conventional metal ion adsorbents include cation or anion exchange resins, polyamine-based and iminoacetic acid-based chelate resins, and the like. These resins adsorb many types of metals indiscriminately and have poor selective adsorption ability for specific useful metals, and have no adsorption ability at all when collecting uranium dissolved in seawater, for example.

Recently, titanic acid, resorcinol arsenate resin, triaminophenol glyoxal resin, etc. have been proposed as having adsorption ability for uranium, but their adsorption ability is small and their shape retention in water is unstable, etc. It has not been put into practical use.

In order to solve the above problems, the present inventors conducted extensive systematic research and completed the present invention. However, it is an object of the present invention to provide a method for producing a heavy metal ion adsorbent having excellent selectivity and adsorption ability, especially for uranium.

That is, the present invention has the general formula (1) R, R□3(l) CONH-R4 (wherein R1, R2, and R3 represent hydrogen or a hydroxyl group, and at least one of them is a hydroxyl group).

R4 represents a lower alkyl group having a carboxyl group at the 1st or 2nd position, or an aryl group having a carboxyl group)
This is a method for producing a heavy metal ion adsorbent, which is characterized by polycondensing a benzoic acid amide derivative represented by the formula and formaldehyde at 40° C. or higher in the presence of an alkaline or acidic catalyst. The benzoic acid amide derivatives represented by the general formula (1) used in the present invention include 2-hydroxyhippuric acid, 2,4-dihydroxyhippuric acid, N-(1-carboxyethyl)-salicylic acid amide, N-(1- carboxyethyl)-resorcinamide, N-(2-carboxyethyl)-salicylic acid amide, N-(2-carboxyethyl)-resorcinamide, N-(2-carboxy)
-Phenyl-salicylic acid amide, N-(2-carboxy)-phenyl-resorcinamide, N-(4-carboxy)-phenyl-salicylic acid amide, N-(4-carboxy)-phenyl-resorcinamide, N-(4-carboxy)-phenyl-resorcinamide, -carboxy-3-hydroxy)-phenyl-salicylic acid amide, N-(4-carboxy-3-hydroxy)-phenyl-resorcinamide, and the like.

Furthermore, examples of formaldehyde include formalin and paraformaldehyde. The polycondensation reaction between the benzoic acid amide derivative represented by the above general formula and formaldehyde is performed using at least 0.8 mol of formaldehyde, preferably 1 to 20 mol, of formaldehyde per 1 mol of the benzoic acid amide derivative.
001 to 1 mole of an acidic catalyst such as hydrochloric acid, sulfuric acid, or phosphoric acid, or an alkali catalyst such as caustic soda, at a temperature of 40°C or higher, preferably 60 to 120°C, for about 5 minutes to 15 hours while stirring. be exposed. In this case, water or an organic solvent such as alcohol or ascent may be used as the reaction medium. The product obtained by the polycondensation reaction is concentrated by heating, or the resin precipitated during the reaction is separated, washed with water, and collected.

The resulting water-insoluble resin exhibits a light brown to blackish brown color,
It has infusibility. The adsorbent obtained by this method shows particularly excellent adsorption ability among benzoic acid amide derivatives, especially when R3 is a hydroxyl group, and 2,4-dihydroxyhippuric acid and N-(1-carboxyethyl)-resorcinic acid amide The hydroxyl group at the 2-position and the carboxyl group at the end serve as ligands, and the chelate-forming ability is extremely excellent, and the hydroxyl group at the 2- and 4-positions makes it easy to polymerize with formalin.

Also, those in which R4 contains a 4-carboxy-3-hydroxyl group, such as N-(4-carboxy-3-hydroxy)-
In phenyl resorcinamide, the hydroxyl group adjacent to the acid amide acts as a ligand, increasing the ability to adsorb heavy metals, and the hydroxyl group at the 3-position and the carboxyl group at the 4-position of the phenyl group have chelate-forming ability, making it highly adsorbable. His ability is excellent. Furthermore, these adsorbents have high selectivity for adsorbing uranium, especially among heavy metals.

The heavy metal adsorbent obtained by the method of the present invention adsorbs heavy metals such as iron, copper, zinc, cadmium, lead, nickel, chromium, and uranium in an aqueous solution, and is particularly selective to uranyl ions.

When adsorbing heavy metal ions using the adsorbent obtained by the method of the present invention, the adsorbent is packed in a column or in the form of a fiber, a thin film, etc., and is brought into contact with water containing heavy metal ions for an appropriate period of time.

Further, when the heavy metal ion-containing water contains a large amount of alkali or acid, it is desirable to adjust the pH to 4 to 9.5 before use. For example, when removing and recovering heavy metals from industrial wastewater, it is preferable to remove water-insoluble substances before use. The adsorbent that has been brought into contact with water containing heavy metal ions may contain acids (e.g. mineral acids), alkalis (e.g. caustic soda, aqueous ammonia, etc.) depending on the metal, water-soluble carbonates (e.g. It is possible to recover the adsorbed heavy metal ions by desorbing and dissolving them by immersing them in an aqueous solution containing water-soluble bicarbonate (eg, sodium bicarbonate, etc.) and water-soluble bicarbonate (eg, sodium bicarbonate, etc.).

The adsorbent obtained by the method of the present invention has extremely high industrial utility value, such as wastewater treatment or recovery of useful heavy metals, especially uranium, from seawater. Examples will be described below.

Example 1 2,4-dihydroxyhippuric acid 107 (0.0474 mol) and 37% formalin 6.2? (0.0711 mol) Add 10 CC of ethyl alcohol, stir at 80°C to dissolve, then add 0.37% hydrochloric acid and stir at 80°C for 5 hours to cause a polycondensation reaction, resulting in a dark brown 2,4-dihydroxy A hippuric acid-formaldehyde resin was obtained.

This resin does not melt even when heated to 130°C or higher, and its infrared absorption spectrum is 1650? -1 has characteristics such as absorption based on carbonyl group. Next, 100T resin
! After immersing 19 in dilute hydrochloric acid for a short time, this was used as an adsorbent to absorb 500p of uranium. In addition to seawater 51 containing
After stirring for 4 days, the resin was separated by sedimentation, and after washing with water,
The adsorbed uranium was desorbed by immersion in 10 cc of hydrochloric acid at 60°C for 30 minutes, and the uranium in the desorption solution was quantified by measuring ultraviolet fluorescence using the sodium fluoride sphere method. As a result, it was found to be equivalent to 80% of the total amount of uranium. It was discovered that 4,001 ku of uranium had been adsorbed. Is this an adsorbent? This means that 40 watts of uranium was adsorbed per unit. In addition, as a comparative example, powders of titanic acid and resorcinol-arsenic acid resin, which are known adsorbents, were each used at 100 W!
An adsorption test was conducted in the same manner as above using 9 as an adsorbent. Converted to 1.8 TIZg and 1, respectively.
,9η of uranium adsorption. However, titanic acid is obtained by neutralizing titanium tetrachloride hydrochloric acid solution with caustic soda. Further, resorcinol arsenic acid resin is obtained by formalin polymerization of resorcinol arsenic acid in a conventional manner.
As mentioned above, the adsorbent produced by the method of the present invention has an excellent ability to adsorb uranium. Example 2 Same as Example 1, 2-hydroxyhippuric acid, 3-hydroxyhippuric acid, 4-hydroxyhippuric acid, 2,4-hydroxyhippuric acid, N-(1-carboxyethyl)-salicylic acid amide, N-( 2-carboxyethyl)-salicylic acid amide, and as a comparative example, N-methyl-salicylic acid amide, N
A resin was obtained by polycondensing -ethyl-salicylic acid amide and 5-amino-salicylic acid amide with formaldehyde.

100 W of each of the obtained resins was added with uranium 5 in the same manner as in Example 1.
00μ? The mixture was added to seawater 51 containing 51% of the total amount of uranium and stirred at 30° C. for 4 hours to adsorb uranium in the seawater.

Next, this resin that had adsorbed uranium was subjected to desorption treatment in the same manner as in Example 1, and the results of uranium analysis are summarized in Table 1. From this, the adsorption capacity increases in the order of N-substituents: carboxymethyl group > 1-carboxyethyl group > 2-carboxyethyl group > 5-amino-hexyl group, especially when it has a carboxyl group at the α or β position. I can see that it is excellent. In addition, in the case of an oxyphenyl group having a carboxyl group in the acid amide group, 2●4-dioxyphenyl group>
2-Oxyphenyl> The adsorption amount increases in the order of 4-oxyphenyl group and 3-oxyphenyl group. In addition, commercially available phenylsulfonic acid-based, aliphatic carboxylic acid-based cation exchange resins, amine-based, quaternary ammonium salt-based anion exchange resins, or polyamine-based iminodiacetic acid-based chelate resins The uranium adsorption capacity was low or almost no adsorption capacity was observed. Example
3 In the same manner as in Example 1, an oxybenzoic acid amide derivative having the N-substituent of the benzoic acid amide derivative shown in the general formula (1) is an aromatic carboxylic acid, and an N-phenyloxybenzoic acid amide derivative as a comparative example. A uranium adsorption test was conducted on 100η of the resin obtained by polycondensation with formaldehyde under the same conditions as in Example 1, and the amount of uranium adsorbed for each adsorbent is shown in Table 2.

From Table 2, for oxybenzoic acid amide, Example 2
2,4-dioxyphenyl group〉2-
It can be seen that the adsorption capacity is higher in the order of oxyphenyl group>4-oxyphenyl group≠3-oxyphenyl group. In addition, for the N-substituent, 4-carboxy-3oxyphenyl group>
Adsorption is highest in the order of 4-carboxyphenyl group>2-carboxyphenyl group. Example 4 Adsorbent 1y produced in Example 1 was added to model wastewater 21 containing 10 ppm each of lead nitrate, mercuric nitrate, cadmium nitrate, and chromic nitrate as metal ions.
After stirring and contacting at ℃ for 3 hours, the adsorbent adsorbing metal ions was separated.

The adsorbent that has adsorbed metal ions is immersed in 1N monohydrochloric acid at 60°C for 30 minutes to desorb and elute the adsorbed metal ions.The adsorbent is then separated and the metal ions in the eluate are separated. Quantification was performed. Specifically, for mercury and cadmium ions, after neutralizing a portion of the eluate, an aqueous solution of sodium diethyldithiocarbamate is added to it, the resulting chelate precipitate is collected on paper, and this is analyzed using fluorescent X-rays. did. Furthermore, chromium ions were measured according to atomic absorption spectrometry. The results are summarized in Table 3.

As is clear from the results in Table 3, the adsorbent according to the method of the present invention exhibited excellent adsorption performance for heavy metals. Example
5 Seawater with 0.1 ppm each of uranyl sulfate, cupric chloride, ferric chloride, and nickel chloride added as metal ions 51? Add 100 watts of the adsorbent prepared in Example to 30'
The mixture was stirred and brought into contact at C for 4 days.

Claims (1)

[Claims] 1 General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (R_1 in the formula
, R_2 and R_3 represent hydrogen or a hydroxyl group, at least one of which is a hydroxyl group. R_4 represents a lower alkyl group having a carboxyl group at the 1st or 2nd position, or an aryl group having a carboxyl group) and formaldehyde are polycondensed at 40°C or higher in the presence of an alkaline or acidic catalyst. A method for producing a heavy metal ion adsorbent, characterized by: 2. The method for producing a heavy metal ion adsorbent according to claim 1, wherein R_3 in general formula (1) is a hydroxyl group. 3 In general formula (1), R_4 is 4-carboxy-3
-A method for producing a heavy metal ion adsorbent according to claim 1, which is a hydroxyphenyl group.