JPS603082B2 - Manufacturing method of heavy metal adsorbent - Google Patents

Description

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

Conventionally, as metal ion adsorbents, cation or anion exchange resins, polyamine-based, imi/acetic acid-based chelate resins, and the like are known.

These resins adsorb many types of metals indiscriminately and have poor selective adsorption properties for specific useful metals. For example, when collecting uranium dissolved in seawater by adsorption, they do not have any adsorption chambers.

Recently, titanic acid, resorcinol arsenic acid resin, triaminophenol glyoxazole resin, etc. have been proposed as having adsorption ability for uranium, but the adsorption capacity is small and the shape retention in water is unstable. It has not been put into practical use for several reasons.

In order to solve the above-mentioned problems, the present inventor conducted extensive systematic research and completed the present invention. Another object of the present invention is to provide a method for producing a heavy metal adsorbent having excellent selectivity and adsorption capacity, especially for uranium. That is, the present invention diazotizes a polyaminostyrene copolymer and then converts it into a 4-hydroxybenzo compound represented by the general formula 01 (wherein R is H or OH and x represents either S, 0, or NH). This is a method for producing a heavy metal adsorbent, which is characterized by carrying out a coupling reaction with imidazole, 4-hydroxybenzoxazole, 4-hydroxybenzothiazole, or a derivative thereof.

The polyaminostyrene copolymer used in the present invention is a polystyrene copolymer, such as styrene-divinylbenzene copolymer, styrene-pinylpyridine copolymer, or styrene-chloromethylstyrene copolymer, which is prepared by mixing with amines. It can be obtained by nitration and reduction of such substances.

It is desirable to nitrate the polystyrene copolymer using a conventional method using a mixed system of concentrated nitric acid and concentrated sulfuric acid at a temperature of 50 to 100°C. If the temperature is lower than 50°C, the reaction rate will be slow and it will take a long time, and if the temperature is higher than 100°C, the substrate will be damaged or susceptible to oxidation.

Further, the reduction of the nitro group to an amino group can be achieved, for example, by heating and refluxing the nitrated polystyrene copolymer with concentrated hydrochloric acid and stannous chloride in ethanol.

If the degree of crosslinking of the polystyrene copolymer is low during nitration, the polymer may melt or become sticky, making it necessary to carry out the reaction over a long period of time.

In this case, there is a mirror direction in which the nitro G ball decreases. In addition, if the degree of crosslinking is too high, the nitroTG rate tends to decrease, which ultimately affects the reaction rate with the penzohydroxamic acid derivative, so it is preferable to select conditions appropriately. When copolymerizing and divinylbenzene by emulsion polymerization or suspension polymerization, the charging ratio of divinylbenzene to styrene is 0.5 to 30 mol%,
Particularly preferably, by setting it to 0.5 to 5 mol%,
It is possible to overcome the above-mentioned difficulties during nitration. In this case, the nitro G ratio is 80 to 95% of the total benzene nuclei. Further, when copolymerizing styrene and chloromethylstyrene, the charging ratio of chloromethylstyrene to styrene is preferably 5 to 100% by mole, and the resulting copolymer is made into powder or fibers and mixed with amines such as an amine having at least difunctionality such as ethylenediamine, jethylenetriamine, triethylenetetramine, piperazine, xylylenediamine and water or methanol;
Alcohols such as ethanol, propanol, butanol, ketones such as acetone, methyl ethyl ketone, and solvents such as acetonitrile, nitromethane, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc., at a temperature of 50 to 90°C from room temperature for 1 to 1 liters.
q Gradually rise and overflow in Terama, process and crosslink.

In this case, if the overflow rate is higher than the above conditions, the surfaces of the powder or fibrous material melt and adhere to each other, forming a gum-like state.

The powdered or fibrous material obtained by this method is highly insoluble and infusible and can withstand nitration conditions.
Further, the nitration rate is 75 to 95% of all benzene nuclei. The polyamide/styrenic copolymer obtained by the above method is then diazotized.

In this case, the shape of the copolymer is preferably powder or fiber. Polyamide/styrenic copolymer
It is immersed in an aqueous solution containing 3 times the molar amount of hydrochloric acid as the base base, and a sodium nitrite aqueous solution is added dropwise at a temperature of 0 to 1 0.

At this time, the saturated amount of bleached sodium nitrate can be determined using iodine starch test paper.

That is, the saturation amount is defined as the point at which the iodine starch paper shows a blue color and does not fade for more than a few minutes. According to this, the amount of amino groups that undergo diazotization in the core polyaminostyrene copolymer can be determined. The copolymer that has undergone diazotization is heated in a furnace of 8U,
4-Hydroxybenzimidazole, 4-hydroxybenzoxazole, 4-hydroxybenzothiazole, or a discussion conductor was gradually added to a 10% caustic soda aqueous solution containing 1 to 10 times the molar amount of amino groups dissolved in a nitrogen atmosphere at -5 to 1 pi○. During the 1st and 2nd year of junior high school, complete the coupling by performing a unique tokuhai.
The compounds represented by the general formula '11 used in the present invention are, for example, 4-hydroxybenzimidazole, 4-hydroxybenzoxazole, 4-hydroxybenzothiazole, 4,6-dihydroxybenzimidazole, 4
-6-dihydroxybenzoxazole, 4,6-dihydroxybenzothiazole, etc.

Confirmation and analysis of reactions in the manufacturing process of the adsorbent of the present invention were performed by the following method.

That is, in the nitration reaction of a polystyrene copolymer, the reaction rate was determined by measuring nitrogen by Kjeldahl nitrogen analysis method, and the amount of nitro groups was determined from this.

In addition, the infrared absorption spectrum of the nitrated polystyrene copolymer has absorptions derived from nitro groups at 1520-1 and 1340-1. In addition, the number of amino groups/groups undergoing diazotization was determined from the saturation amount of sodium nitrite during diazotization.

This confirmed that 95 to 100% of the nitro groups were reduced to amino groups. Further, the reaction rate of the coupling between the diazotized polyaminostyrene copolymer and the compound represented by the general formula '1' can be determined by measuring the absorbance of the aqueous solution containing the coupling component before and after the reaction.

Absorbance measurements are made between 350 and 23 degrees, and it is more accurate to use the maximum absorption.

The reaction rate determined from this was 25 to immediate % of the amount of diazotized amino groups. The adsorbent obtained by the method of the present invention was subjected to nitrogen analysis using the Kjeldahl method, and the coupling reaction rate estimated from this value was within a 10% error of the reaction rate determined from absorbance measurement. The heavy metal adsorbent obtained by the method of the present invention adsorbs heavy metals such as iron, uranium, zinc, copper, nickel, cadmium, lead, chromium, and manganese in an aqueous solution, and exhibits selectivity for uranylion in particular.

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

- Also, if the heavy metal ion-containing water contains a large amount of alkali or acid, it is desirable to adjust it to a value of 4 to 9.5 before use.

For example, when removing and recovering heavy metals from industrial wastewater, it is preferable to adjust the pH to 5 to 9 after removing water from the water. The ion adsorbent that has been brought into contact with water containing heavy metal ions is an acid (e.g. sulfuric acid, nitric acid, hydrochloric acid, etc.)
Also, depending on the metal, it may be immersed in an aqueous solution containing alkali (e.g., caustic soda, aqueous ammonia, etc.), water-soluble carbonate (e.g., sodium carbonate, ammonium carbonate, etc.), water-soluble bicarbonate (e.g., sodium bicarbonate), etc. The adsorbed heavy metals can be desorbed, dissolved and recovered.

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

Examples will be described below.

Example 1 To 1 M of styrene containing 1 mol % of divinylbenzene, add 2 parts of surfactant (1 night of Kao Atlas's EMAR 10, 1 night of Kyoeisha Yushi Co., Ltd./Niolite PN-12), and add 250 cc of water. Emulsify the mixture, add 0.1 tsp of potassium persulfate in a nitrogen stream, and heat vigorously at 80°C.

After 3 hours, 70 g of styrene containing 1 mol% dipinylbenzene was added dropwise over 1 hour, and the system was further heated for 5 hours.
Rinse at 80℃.

The resulting latex is destroyed by adding concentrated hydrochloric acid, and the polystyrene copolymer is separated from the furnace and washed. This polystyrene-based copolymer powder was dried, and then mixed with 15 cc of concentrated nitric acid and 4 ml of concentrated sulfuric acid.
While worshiping the light with 7 pi○ in 0cc, add it for 2 hours,
After reacting for another 3 minutes at 70:00, pour over crushed ice.

The nitrated polystyrene copolymer thus obtained was thoroughly washed and then dried. The total amount of nitrogen in the obtained copolymer was measured by the Kjeldahl method, and it was found that the copolymer contained 0.65 mM of nitrogen in 10 false samples.

Calculating the nitration rate from this, the scale% of all benzene nuclei is
is undergoing nitration. Subsequently, the copolymer was heated under reflux for 1 hour in 80 cc of ethanol and 70 cc of concentrated hydrochloric acid over 10 minutes of stannous chloride dihydrate, washed with water, washed with caustic soda, washed with water, and diazotized. Let's do it.

As a result of measuring the total nitrogen amount by Kjeldahl method, it was found that the 100M sample contained 0.80mM nitrogen.

Therefore, when calculated from this value, it is considered that the nitro group is almost completely reduced to an amino group. This aminated polystyrene copolymer was mixed with 25 cc of water and 25 mL of hydrochloric acid.
Suspended in cc, cooled on ice and kept below 5℃, while stirring vigorously, a 1 molar solution of sodium nitrite was gradually added dropwise.
．． At 8 cc, the iodine starch test paper exhibited a clear blue-purple color. Therefore, it is considered from this value that almost all of the nitro groups were reduced and that 97 to 99% of the amide/groups were diazotized. The diazotized copolymer is thoroughly filtered and washed with ice water.

4-Hydroxybenzimidazole was dissolved in 50 cc of 10% caustic soda, and the diazotized copolymer was added little by little while keeping the temperature at 0 to 3°C in a nitrogen atmosphere.
The coupling reaction was carried out by heating at ℃ for 2 hours.

After the reaction was completed, the powdered resin was filtered, washed with water, and air-dried to obtain an adsorbent. The coupling reaction rate was determined by measuring the absorbance of 4-hydroxybenzimidazole in the solvent before and after the reaction.

Sample the reaction solution LCC and add 2.5% caustic soda to
That's it. This absorbance was measured using UV-200 manufactured by Shimadzu Corporation at 25 meters. Calculating from this, 3
This means that 0mM of 4-hydroxybenzimidazole has reacted. Therefore, the percentage of diazotized amino groups
is thought to have performed the coupling reaction. A uranium adsorption test was conducted on the adsorbent thus obtained.

100 ml of adsorbent was added to 50 ml of natural seawater to which 500 uranium was added as uranyl nitrate, heated at 30°C for 24 hours, and the adsorbent was dried in a 3U oven using Geigerflex SX crab manufactured by Rigaku Denki. Uranium was determined by optical X-ray analysis.

As a result, 415 r of uranium was adsorbed per 10 touches of adsorbent. This means that 4.15 tons of uranium were adsorbed per night of adsorbent, and that % of the total uranium was recovered. As a comparative example, we conducted an adsorption test in the same manner as in the above method using 10 powders of each of known adsorbents titanic acid, resorcinol-arsenic acid resin, and 2,4,6-triaminophenol-glyoxal resin as adsorbents. are shown in Table 1. 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. Also, 2, 4, 6
-Triaminophenol-glyoxal resin is 2.4
- Obtained by condensation polymerization of 6-triaminophenol and glyoxal in an acidic medium. Table 1 Next, the adsorbent subjected to crab light X-ray measurement was taken out and immersed in 10 cc of IN hydrochloric acid at 70°C, and the same treatment was performed once again to elute the uranium and remove the uranium from the solution using sodium fluoride. As a result of measuring ultraviolet light using a sphere method, the amount of uranium in the eluate was 410 Muta.

Therefore, the uranium adsorbed on the 4-hydroxybenzimidazole-azostyrene resin is easily and almost completely desorbed. As mentioned above, it can be seen that the adsorbent according to the present invention has an excellent uranium adsorption capacity and is also very good in terms of adsorption rate and selectivity.

Example 2 A styrene-divinylbenzene copolymer was prepared at a charging ratio of divinylbenzene to styrene of 0 to .・40 mol%
A copolymer was obtained by emulsion polymerization while changing between

Emulsion polymerization was carried out in the same manner as in Example 1, and nitration, reduction, and diazo coupling of the obtained copolymer were carried out in the same manner as in Example 1 to obtain an adsorbent. When carrying out the diazo coupling, 4,6-dihydroxybenzoxazole was used to react 100% of the polyaminostyrene copolymer with 100% of the polyaminostyrene copolymer, and the reaction rate was measured by the absorbance of 200% of the polyaminostyrene copolymer. The bound adsorbents 10 and 9 were placed in an aqueous solution containing lead nitrate so that the lead concentration was 1 foot, and the mixture was kept at room temperature for 24 hours. It was drawn up using the line method. The results are shown in Table 2.

Table 2 From Table 2, the copolymerization ratio of dipinylbenzene is 3.
If it exceeds 0 mol%, the diazotization equivalent decreases significantly, making it unsuitable for practical use.

At the same time, the amount of lead adsorbed also appears to be decreasing synergistically. Polystyrene that does not contain divinylbenzene is
It is thought that the number of functional groups in the polymer decreased because the nitration conditions had to be relaxed. That is, it can be seen that the copolymerization ratio of divinylbenzene to styrene is preferably in the range of 0.5 to 30 mol%, more preferably 0.5 to 5 mol% for the hakama. Example 3 85 parts of styrene was mixed with 25 parts of chloromethylstyrene, and polymerization was carried out at 80°C using penzoyl peroxide as an initiator in a sealed tube purged with nitrogen.
The fibers are melted and removed at 80°C to obtain fibers with a diameter of 10 liters.

This was immersed in a 20% ethanol solvent of diethylenetriamine, heated for 3 hours at 3-0, and then heated for 3 hours to 7
Gradually raise the temperature to 0 and then treat for 7 more hours for 2 hours. The fiber thus obtained was subjected to a nitration-reduction diazo coupling reaction in the same manner as in Example 1.

When carrying out the diazo coupling, 4-hydroxybenzothiazole was used to react 1 piece of fiber with 30 pieces of fiber, and the reaction rate was determined by absorbance at 26 pieces. In each reaction, about 90% of the total benzene nuclei were nitrated, and the diazotized amino/group was 7.1 wM/2.8 mM of the reacted amount of 4-hydroxybenzothiazole.

300 pieces of this fibrous adsorbent were packed into a 1 piece column to a length of 5 pieces.

Ferric nitrate, ferric chloride, cadmium nitrate, uranyl nitrate, zinc chloride, lead nitrate, nickel acetate, chromic acetate, and manganese (b) nitrate were used to reduce the concentration of each heavy metal to 0.
An aqueous solution was prepared, and this solution was passed through the above column for 2 q of life, and the heavy metals adsorbed on the fibers were determined by crab light X-ray analysis.

The results are shown in Table 3.

As is clear from Table 3, the heavy metal adsorption capacity of the fiber was excellent, and in particular, it is thought that almost all of the uranylion was adsorbed.

In addition, when desorbing heavy metals from fibers on which heavy metals have been adsorbed, desorption chambers were investigated using hydrochloric acid, sulfuric acid, nitric acid, caustic soda, bicarbonate of soda, soda carbonate, and ammonium carbonate.

As a desorption method, 100% of the fiber adsorbent was mixed in 25 cc of each 0.9Y solution at 50°C for 3 cycles, and this operation was repeated twice.Then, the amount of heavy metals in the fibers was measured by optical X-ray analysis. did. As a result, when hydrochloric acid, sulfuric acid, and nitric acid were used, the desorption rate for each metal was between 96 and 100%, but when hydrochloric acid was used, the desorption rate for lead was 54%. Example 4
The polyaminostyrene copolymer used in Example 1 was diazo-coupled with 4-hydroxybenzimidazole, 4-hydroxybenzoxazole, and 'C14-hydroxybenzothiazole in the same manner to form an adsorbent. (A, B, C) were produced.

At this time, the coupling reaction was measured in the same manner as in Example 1, and the wind was 41%, 'B' was 40%, and 'C' was 39%, respectively. Using the heavy metal salts used in Example 3, 10 2 nuclear adsorbents were added to an aqueous solution 5Z in which each metal concentration was 0.5 rM, and the adsorbent was mixed for 2 hours. It was determined by the line. The results are shown in Table 4.

Table 4 As is clear from the results shown in Table 4, the adsorbent produced by the method of the present invention has excellent adsorption of heavy metal ions and particularly high selectivity for iron and uranyl ions.

Claims (1)

[Claims] 1. After diazotizing the polyaminostyrene copolymer
General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is H or OH, and X is S, O, or NH
A method for producing a heavy metal adsorbent, which comprises subjecting 4-hydroxybenzimidazole, 4-hydroxybenzoxazole, 4-hydroxybenzothiazole, or a derivative thereof to a coupling reaction.