JPS6152164B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel chelate resin suitable for adsorbing and recovering trace amounts of dissolved metal ions from seawater, other natural waters, industrial wastewater, and the like.

In order to adsorb and recover dilute trace amounts of metal ions such as uranium in seawater, an adsorbent with high adsorption rate and adsorption capacity is desirable, and also has high stability against the liquid to be treated such as seawater and the desorption treatment liquid. This is very important.

On the other hand, hydroxamic acid compounds are known to form chelate complexes with many heavy metal ions.
Taking advantage of its properties, it is used to quantify and separate heavy metal ions by solvent extraction, and attempts are also being made to apply it to recovery of heavy metal ions from mine drainage by flotation.

Hydroxamic acid compounds form chelate complexes with a wide variety of heavy metal ions, including transition metals such as titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, cadmium, tin, hafnium, tungsten, and mercury. , bismuth, etc.; lanthanide series include praseodymium, neodymium, samarium, gadolinium, and dysprosium; actinide series include protactinium, uranium, neptunium, plutonium, etc.

In order to take advantage of the heavy metal adsorption properties of hydroxamic acid compounds and use them as adsorbents, for example, to adsorb and collect uranium from seawater or to adsorb and recover trace amounts of metal ions dissolved in wastewater, hydroxamic acid compounds are needed. It is necessary to introduce and immobilize it into a stable polymer.

Polyacrylic hydroxamic acid is known as a polymer with such a hydroxamic acid structure immobilized, and it is also known that this resin has good adsorption and collection ability for metal ions such as copper ions [W. Kern, RC Schulz, Angew.Chem., 69 ,
153 (1957), Ryuichi Yamamoto et al., Koka, 70 (5), 152
(1967)). This polyacrylic hydroxamic acid is produced by reacting polyacrylic ester with hydroxylamine, but the reaction does not necessarily proceed smoothly, and a considerable amount of the ester moiety remains in the residue where hydroxamic acid is formed. However, it is difficult to form a chelate resin with high adsorption capacity.

The present inventors have overcome the conventional problems of such methods of introducing and immobilizing hydroxamic acid groups into polymers, and have attempted to incorporate as many hydroxamic acid groups as possible, preferably adjacently on the same carbon. As a result of intensive research on a method for forming a stable chelate resin introduced into polystyrene, it was discovered that the objective could be achieved by introducing dihydroxamic acid groups into polystyrene crosslinked via divinylbenzene, and the present invention I was able to accomplish this.

That is, the present invention involves reacting chloromethylated polystyrene crosslinked via divinylbenzene with di-lower alkyl malonic acid ester,
general formula (R in the formula is a lower alkyl group) and then reacting it with hydroxylamine, or divinylbenzene is added to the reaction mixture of chloromethylstyrene and malonic acid di-lower alkyl ester. In addition, by carrying out suspension polymerization to form a polystyrene derivative having a crosslinked structure, and then reacting this with hydroxylamine, the formula (a) The structural unit represented by (b) Eq. The structural unit represented by and (c) formula The present invention provides a method for producing a chelate resin consisting of the structural unit represented by:

The chelate resin obtained by the method of the present invention has the formula A dihydroxamic acid residue represented by is introduced, and two free hydroxamic acid groups exist for one aromatic nucleus. Furthermore, since these two hydroxamic acid groups are bonded to one carbon atom and are adjacent to each other via that carbon atom, they are suitable for cooperatively bonding to metal ions. Further, the chelate resin of the present invention is made of a crosslinked polystyrene polymer compound, and is an extremely stable adsorbent having excellent chemical resistance, acid resistance, alkali resistance, and heat resistance, and has high practical value.

In order to produce a chelate resin having a dihydroxamic acid residue represented by the above formula () by the method of the present invention, its precursor, the general formula (R in the formula represents a lower alkyl group) Two methods can be adopted depending on the method for forming the benzylmalonic acid dialkyl ester residue represented by the following.

The first method is to react chloromethylated crosslinked polystyrene obtained by a known method with di-lower alkyl malonic acid ester to produce a resin having a residue represented by the general formula (), and then add hydroxylamine to this resin. It causes a reaction. In the initial reaction between chloromethylated crosslinked polystyrene and malonic acid dialkyl ester, a strong base is used as a dehydrochlorination condensing agent, and sodium hydride is particularly suitable. The malonic acid diester can be converted to its carbanion with a strong base beforehand and then the chloromethylated crosslinked polystyrene can be reacted. Solvents used in this reaction include polar solvents, especially dimethylformamide,
Aprotic solvents such as N-methylpyrrolidone and dimethyl sulfoxide, and ether solvents such as tetrahydrofuran and ethylene glycol dimethyl ether are preferred. The reaction temperature can be carried out in a wide range from room temperature to the boiling point of the solvent, but 50°C to 100°C is particularly suitable. Further, the reaction time depends on the reaction temperature, but is usually in the range of 5 hours to 30 hours.

The thus obtained resin having a residue represented by the general formula () is suspended in a solvent containing hydroxylamine and reacted for 1 to 4 days at a temperature ranging from room temperature to the boiling point of the solvent. It is extremely effective to use methanol or ethanol alcoholate as a catalyst to promote this reaction.
The reaction solvent is preferably one that has affinity with the resin, and the most suitable is a mixed solvent of an alcohol such as methanol, ethanol, isopropyl alcohol, and a hydrocarbon such as benzene, toluene, xylene.

According to this method, an ester can be hydroxamed oxidized at a much higher reaction rate than when a polyacrylic ester is reacted with hydroxylamine. This is presumed to be because the ester group of malonic acid is more activated due to its electron-withdrawing effect.

The second method for obtaining a chelate resin having a residue represented by the general formula () is to first condense chloromethylated styrene and dialkyl malonic acid ester to produce vinylbenzyl malonic ester, and then use this polymerizable monomer. is polymerized with divinylbenzene by a known method to obtain the general formula ()
After producing a crosslinked resin having a residue represented by the formula, hydroxylamine is reacted in exactly the same manner as in the first method.

The crosslinked resin of vinylbenzene malonic acid ester can be provided with various states of porosity, like other crosslinked resins, depending on the polymerization conditions. For example, macroporous resins can be formed when suspension polymerization is carried out in the presence of an inert solvent such as toluene, or alternatively, polymerization can be carried out in the presence of poor solvents such as alcohols. A macroreticular resin can be obtained. In this way, it is possible to easily produce resin in any form depending on the purpose and use.

The chelate resin having a dihydroxamic acid group represented by the general formula () obtained by the above method has an excellent adsorption ability for the various metal ions mentioned above, and for example, exists in seawater at only about a few ppb. It can adsorb and collect extremely low concentrations of uranium with high efficiency, and also efficiently adsorb and collect trace amounts of other valuable metals, such as cobalt, nickel, copper, zinc, and strontium, and easily separate and recover them. Therefore, it is an extremely useful adsorbent for adsorption and recovery of metal ions.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these explanations.

Example 1 A solution of 5.6 g (0.035 mol) of malonic acid diethyl ester dissolved in 30 ml of dimethylformamide was added to a solution of 0.72 g (0.03 mol) of sodium hydride suspended in 70 ml of dimethylformamide.
After heating to 60°C and completing the reaction for 1 hour, the mixture was returned to room temperature and 2 g (Cl: 0.01 mol) of chloromethylated polystyrene crosslinked with divinylbenzene (Cl: 18.9%) was added. , 80
It was heated to ℃ and allowed to react for 24 hours. As a result of infrared absorption spectrum measurement of the reaction product, it was confirmed that malonic acid diester groups were introduced into polystyrene. In addition, the reaction rate was determined from the amount of chlorine reduction, and the reaction rate was 85.9%.

After immersing 10 g (0.0982 mol) of this polymer in dry benzene for about 34 hours, a methanol solution of hydroxylamine (0.393 mol) was added, and 7.9 g (0.344 mol) of sodium metal was added while cooling on ice.
After adding 100 ml of methanol solution and keeping the mixture under ice-cooling for an additional hour, the mixture was returned to room temperature, and then heated to 70°C and reacted for 2 days.

The reaction product was washed with ice-cold water and then cooled on ice.
It was treated with 0.5NHCl to form H ⁺ form, and further washed with water until the washing solution became neutral. Next, this was washed with methanol and then vacuum dried. As a result of infrared absorption spectrum measurement, the ester group was completely reacted, and in addition to hydroxamic acid, some carboxylic acid was observed to be produced. As a result of elemental analysis, the production rate of hydroxamic acid is
It was 56.4%.

Example 2 8.4 g (0.35 mol) of sodium hydride was added to 125 ml of tetrahydrofuran and suspended, and then a solution of 80 g (0.5 mol) of malonic acid diethyl ester in 75 ml of tetrahydrofuran was added. After the mixture was cooled to room temperature, a solution of 45.75 g (0.3 mol) of chloromethylated styrene in 30 ml of tetrahydrofuran was added dropwise, and after adding 1 g of sulfur powder as a polymerization inhibitor, it was allowed to stand for about 1 hour.
Thereafter, the mixture was heated to 70°C and reacted for 21 hours. After the reaction, tetrahydrofuran was distilled off, and about 200 ml of ethyl acetate was added to the reaction product concentrate, which was washed several times with ice-cooled 1NHCl aqueous solution, and then washed several times with ice-cold water, and then anhydrous magnesium sulfate was added. and dried overnight. Next, ethyl acetate was distilled off, 1 g of sulfur powder was added, and vacuum distillation was performed to obtain a 0.2 mmHg
Vinylbenzylmalonic acid diethyl ester was obtained as a fraction with a boiling point of 148°C to 150°C. The reaction rate was 55%.

Add 0.25g of polyvinylpyrrolidone to water as a stabilizer.
Dissolve in 40 ml, stir vigorously, and add 7 ml of divinylbenzylmalonic acid diethyl ester obtained as above, 2 ml of divinylbenzene,
5 ml of toluene and several grams of precipitant were added as a solvent. After adding 0.1 g of azobisisobutyronitrile as a polymerization initiator, the reaction was carried out at a temperature of 80° C. for 26 hours while purging the reaction system with nitrogen gas. After the reaction was completed, the granular product was separated and washed with water, and then washed with acetone overnight using a Soxhlet extractor and dried under vacuum. When no precipitant was added, a gel porous granular product was obtained, whereas when methylcyclohexane, cyclohexanol, n-butanol, etc. were used as a precipitant, an opaque macroreticular type granular product was obtained. In addition, as a result of infrared absorption spectrum measurement of these products, the same spectrum as in Example 1 was obtained, and it was recognized that they were crosslinked copolymers.

Hydroxamic oxidation was carried out in the same manner as in Example 1 to obtain a dihydroxamic acid type chelate resin.

Application Example 10 ml of the dihydroxamic acid type chelate resin obtained in Example 1 was packed into a column with an inner diameter of 3 cmφ, and natural supersea water was passed through the column in an upward flow at SV=390 hr ⁻¹ and temperature of 25±2° C. After passing water for 26 days, wash the adsorbent with water.
After drying, qualitative analysis of the adsorbed elements using fluorescent X-ray method revealed that in addition to uranium, cobalt, nickel, copper, zinc, and strontium were detected as metals, indicating that the dihydroxamic acid type chelate resin
It was recognized that it has a high selective adsorption ability for first transition metals and uranium.

The metal ion adsorption properties of the macroreticular dihydroxamic acid resin obtained in Example 2 were also examined under the same conditions, and the same results as above were obtained.

Claims (1)

[Claims] 1. By reacting chloromethylated polystyrene cross-linked via divinylbenzene with di-lower alkyl malonic acid ester, the general formula (In the formula, R is a lower alkyl group) The formula (a) is characterized by introducing a group represented by the following and then reacting the group with hydroxylamine. The structural unit represented by (b) Eq. The structural unit represented by and (c) formula A method for producing a chelate resin consisting of a structural unit represented by: 2. Divinylbenzene is added to a reaction mixture of chloromethylstyrene and di-lower alkyl malonic acid ester, and suspension polymerization is carried out to form a polystyrene derivative having a crosslinked structure, which is then reacted with hydroxylamine. , (a) Eq. The structural unit represented by (b) Eq. The structural unit represented by and (c) formula A method for producing a chelate resin consisting of a structural unit represented by: