JPS58223439A - Adsorbent for heavy metal, production thereof and adsorptive treatment - Google Patents

Abstract

PURPOSE:To provide high adsorptive power for heavy metals and to improve the rate of adsorption as well by depositing water soluble amines, a water soluble epoxy crosslinking agent and the resulted product of reaction of carbon disulfide or its salt on active carbon. CONSTITUTION:Water soluble amines (e.g., hydrazine hydrate) are deposited on active carbon in the presence of water, and the deposited water soluble amines are caused to react with a water soluble epoxy crosslinking agent (e.g., ethylene glycol diglycidyl ether), and are then treated with carbon disulfide or is treated with carbon desulfide and base. The water soluble amines, the water soluble epoxy crosslinking agent and the resulted product of carbon disulfide or its salt are deposited on the active carbon in the above-mentioned way. The resulted adsorbent has high selectively to heavy metals, more particularly mercury, hexavalent Cr, Cd, copper, iron, etc. and can remove the heavy metals when brought into contact with an aq. soln. contg. heavy metals. The adsorbent has excellent chemical stability and the rate of adsorption as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel heavy metal adsorbent, its manufacturing method, and adsorption treatment method.

Conventionally, the number of industrial wastewater, testing laboratory wastewater, etc. was 10μ/l.

Iminodiacetic acid type chelate resins are highly evaluated as being effective in removing heavy metal ions from solutions containing less heavy metal ions, and are widely used for the tertiary treatment of wastewater. Although the above iminodiacetic acid type chelate resin has excellent heavy metal adsorption ability, it has poor selectivity between one heavy metal ion, and when alkaline earth metal ions are shared, it is affected by low concentration treatment of heavy metal ions.
Furthermore, it is not always satisfactory for treating a wide variety of complex wastewater, such as the inability to adsorb and remove heavy metal ions dissolved in anionic form.

More selective heavy metal adsorbents are being developed.
In particular, thiourea is used for mercury ions, which require low concentration treatment (0,005~/or less).

So-called mercury chelate resins having thiol, dithiocarbamine, etc. as chelate groups have been put into practical use.

However, these mercury chelate resins are not fully satisfactory because they have a low adsorption rate and cannot be treated in large quantities, and cannot remove organic mercury and colloidal mercury contained in hospital wastewater.

There is still room for further improvement.

Further, as a single heavy metal adsorbent, dithizone, thionalide, 2-mercaptobenzothiazole, thiourea, thiosemicarbazide, etc. are adsorbed and supported on an adsorbent porous carrier such as activated carbon (for example).

(Japanese Patent Publication No. 47-8281, 53-22554, 54-8474) and those in which aldehyde condensation resins or isocyanate resins are adsorbed and supported (for example, JP-A-48-22374, 48-8409).
Publication No. 2) etc. have already been proposed. However, the key to actually passing liquid through these heavy metal adsorbents using a column method etc. is the elution of the adsorbed and supported substance, adsorption rate, adsorption capacity, etc.
Currently, there are many points to consider, such as mechanical strength, and an economical and practical adsorbent has not yet been obtained.

As a result of intensive research to solve this problem, the present applicant found that treating activated carbon with a water-soluble amine and carbon disulfide provides an extremely simple and economical method for adsorption after water treatment (after washing with large amounts of water). It was discovered that a heavy metal ion adsorbent with almost no decrease in performance could be obtained, and the obtained adsorbent could absorb heavy metal ions.

In particular, it has excellent selectivity and adsorption capacity for mercury ions,
They also discovered that the adsorbent had an excellent service life, and filed a patent application (Japanese Patent Application Laid-open No. 159835/1983). However, the adsorbent described in JP-A-55-159835 contains 1 heavy metal and 2% mercury.

High selectivity and adsorption capacity for silver, heat resistant,
Although it has excellent chemical resistance, it has a low adsorption capacity for heavy metals other than mercury and silver, such as lead, copper, cadmium, hexavalent chromium, and antimony.

The adsorption rate was also not sufficient for water and silver.

Therefore, the inventors of the present invention conducted further intensive research to improve these points, and found that when activated carbon is impregnated with a reaction product of water-soluble amines, a water-soluble epoxy cross-linking agent, and carbon disulfide, or a reaction product thereof, mercury.

It has excellent adsorption ability not only for silver, but also for mercury and heavy metals other than silver, such as lead, copper, cadmium, hexavalent chromium, antimony, iron, and nickel, and also improves adsorption speed. Heading.

The invention has been completed.

That is, the present invention uses activated carbon and water-soluble amines.

A heavy metal adsorbent prepared by impregnating a water-soluble epoxy cross-linking agent and a reaction product of carbon disulfide or its salt; and a water-soluble amine impregnated with activated carbon in the presence of water; Water-soluble amines,
A method for producing a heavy metal adsorbent impregnated with a reaction product of a water-soluble epoxy cross-linking agent and carbon disulfide, or a salt thereof, and a reaction product of water-soluble amines, a water-soluble epoxy cross-linking agent, and carbon disulfide on activated carbon. This is a method for adsorption treatment of a heavy metal-containing solution, which comprises bringing a heavy metal adsorbent impregnated with a metal or a salt thereof into contact with a heavy metal-containing solution.

The adsorbent of the present invention is one in which a reaction product of water-soluble amines, a water-soluble epoxy crosslinking agent, and carbon disulfide or a salt thereof is impregnated, but unreacted water-soluble amines and water-soluble epoxy A crosslinking agent, carbon disulfide or a base may be impregnated.

The activated carbon used in the present invention may be of any type, but one activated at a relatively low temperature in a coconut grain layer is particularly preferred because of its high ability to adsorb heavy metals.

This is thought to be due to the fact that the palm grain layer has a lower iron content and a smaller average pore diameter than the coal-based layer. In addition, the particle size of activated carbon is an important factor that controls the rate of 2-flow, and is 10 to 100 mesh.

Preferably 20 to 60 meshes are used.

The water-soluble amines used in the present invention include those containing at least two primary or secondary amino groups in two molecules, one primary amino group and one secondary amine group. . ), the solubility in water is at least 5 times at 20°C
I like things that are good.

Examples of these include aliphatic polyamines such as hydrazine hydroxide, guanidine, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and octamethylenediamine; 9m-phenylenediamine, p-phenylenediamine, m-phenylenediamine; Xylene diamine, p-xylene diamine, 2.4-diaminophenol, 2.4-diaminotoluene.

2.6-diaminotoluene, 2.2'-diaminophenylmethane, 2.4'-diaminodiphenylmethane, 4゜4'-diaminodiphenylmethane, 3.5-diaminobenzoic acid, p-diaminoazobenzene, 4.4-diamino Examples include aromatic polyamines such as diphenylamine, 1.2.4.5-tetraaminobenzene, polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethyle, nbenthamine, and pentaethylenehexamine, and their congeners polyethyleneimine. It will be done. Among them, polyethyleneimino shows particularly excellent adsorption ability, but this is probably related to the introduction rate of metal ligand per unit weight, adsorption ability to activated carbon, and difficulty in being removed by water. It will be done. In addition, polyethyleneimine can be used in either a linear or branched form, and its molecular weight is 300 to 10,000.
Although it can be used in the range of 0, it is preferably 600 to 6,000 in consideration of the adhesion rate and drop-off property. These polyethyleneimines can be used after being appropriately diluted with water.

The water-soluble epoxy crosslinking agent used in the present invention has a molecular weight of 9, contains at least two epoxy groups or episulfide groups (also includes - epoxy groups and one episulfide group), and has a solubility in water of at least 20C. 3% by weight.

Examples of these include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl, tetraethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, fluoropylene glycol diglycidyl 2-thyl, and polypropylene glycol diglycidyl ether. Diglycidyl ether compounds of glycols such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane diglycidyl ether, pentaerythritol diglycidyl ether, pentaerythritol triglycidyl ether, sorbitol tetraglycidyl ether, diglycerin triglycidyl Examples include polyglycidyl ether compounds of polyhydric alcohols such as ethers, and glycidyl ether compounds in which part or all of the epoxy groups are replaced with episulfide groups. Among them, glycerin diglycidyl ether, glycerin triglycidyl ether, propylene glycol diglycidyl ether,
Sorbitol tetraglycidyl ether is particularly preferred.

Examples of the base used in the present invention include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, ammonium hydroxide, sodium carbonate,
Carbonates such as potassium carbonate.

Bicarbonates such as sodium bicarbonate, aqueous ammonia.

Examples include amines. Among them, sodium hydroxide,
Potassium hydroxide is particularly preferred.

To produce the adsorbent of the present invention, first, as a first step, water-soluble amines are impregnated onto activated carbon in the presence of water. At this time, the impregnation rate of water-soluble amines has a great influence on the heavy metal removal ability of the resulting adsorbent, and is usually 1 to 40
l! Amine concentration and impregnation temperature so that X%, preferably 3 to 25% by weight.

It is preferable to adjust the attachment time. The amine concentration is preferably 1 to 50% by weight, particularly preferably 2 to 20% by weight. The impregnation temperature and time are not necessarily constant depending on the type of activated carbon used, particle size, type of water-soluble amine, concentration, molecular weight, and other conditions, but usually θ~7 (30 minutes to 10 hours at Ic). All you have to do is attach it.

Preferably, the temperature is 10 to 50°C for 1 to 5 hours.

It is preferable to separate the water-soluble amine-impregnated carbon thus obtained by p-filtration or the like to remove unadsorbed amine, and then perform a second three-dimensional treatment. This is because of K.

Since the water-soluble amine can be reused and does not generate fine reaction products, clogging during passage through the column can be prevented.

Next, this water-soluble amine-impregnated carbon and a water-soluble epoxy crosslinking agent are reacted in the presence of water to perform three-dimensional processing. As for the reaction temperature at this time.

It is usually carried out at 0 to 150°C, preferably 10 to ioo°C, but temperatures below 0°C are not preferred because the reaction rate becomes slow. A reaction time of 10 minutes to 5 hours is sufficient, but a longer reaction time is also possible. In addition, the amount of water-soluble epoxy crosslinking agent used is not necessarily constant depending on the type of water-soluble amine impregnated, but 9
Usually, 0.02 to 1.0 equivalent in terms of epoxy group or episulfide group, preferably 0 to 1 equivalent of primary or secondary amino group in the impregnated water-soluble amine.
．． 05 to 0.5 equivalent. If it is smaller than 002 equivalent,
It is preferable because the three-dimensional reaction does not proceed sufficiently and elution with water tends to increase, and if it exceeds 1.0 equivalent, the reaction with carbon disulfide tends to be suppressed and the double metal adsorption capacity tends to decrease. do not have.

In the third step, this three-dimensionally treated impregnated coal is then treated with carbon disulfide or with carbon disulfide and a base. At this time, it may be reacted with carbon disulfide in the presence of a base, or it may be treated with a base after the reaction with carbon disulfide. The reaction temperature at that time is 0 to 90°C.
, preferably at the reflux temperature of carbon disulfide. Generally, a reaction time of 5 minutes to 5 hours is sufficient, but a longer reaction time is also possible. Further, the amount of carbon disulfide is 0.1 equivalent or more F, preferably 0.5 to 1.0 equivalent per equivalent of primary or secondary amine group in the impregnated water-soluble amine. It is equivalent. If the amount is less than 0.1 equivalent, the amount of carbon disulfide introduced into the adsorbent tends to decrease and the adsorption capacity for 9 heavy metals tends to decrease, which is not preferable. In addition, the base treatment is not necessarily constant depending on the type and concentration of the base used, but in general, the treatment temperature is 0 to 100C, preferably 10 to 50C, and the treatment time is 10 minutes. The above is used. Furthermore, the amount of the base used is 1 equivalent or more, preferably 1 to 5 equivalents, per 1 equivalent of carbon disulfide used in one reaction.

The adsorbent thus produced can be used as it is or after being washed and dried.

The adsorbent of the present invention has high selectivity for nine heavy metals, particularly mercury, silver, hexavalent chromium, antimony, cadmium, copper, iron, and uranyl.

It can be removed by contacting with a mold metal aqueous solution in the same manner as a normal chelate resin.

As a contact method, simply mix the adsorbent with the solution.

A batch method in which the liquid is shaken and a column method in which the liquid is packed in a column and passed through are used, but the column method is generally used.

The temperature of the heavy metal-containing solution at that time is 9 usually 15 to 15.
A suitable temperature is 50°C, and a suitable contact time is 3 minutes to 2 hours.

The adsorption method of the present invention is useful for removing mercury from smoke washing wastewater from garbage incinerators, treating wastewater from mercury battery and lead-acid battery manufacturing plants, and treating wastewater from nickel and chrome plating plants. Furthermore, it is useful for purifying wastewater containing organic mercury compounds such as thimerosal and mercurochrome.

According to the present invention, heavy metal adsorbents can be produced in an extremely simple and economical manner.

The resulting adsorbent contains heavy metals other than mercury and silver.

For example, lead, antimony, hexavalent chlorine, and uranyl.

It has adsorption ability for cadmium, copper, iron, nickel, etc., and has excellent chemical stability and adsorption speed, so it can quickly remove heavy metals from vinegar solution containing 9 heavy metals and at extremely low concentrations. Since it can be removed in minutes, it can be effectively used to remove heavy metals from industrial wastewater and wastewater from various testing laboratories.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Reference Example 1 Propylene glycol diglycidyl ether (Denacol EX-911. Nagase Sangyo 'I 1.og).

0.50 g of ammonium thiocyanate was dissolved in 10 g of water and reacted at 25 to 30° C. for 24 hours to obtain a product.

The results of elemental analysis (S%) of the obtained product showed that the conversion rate of epoxy groups to episulfide groups was 50.

This product could be utilized for the synthesis of the it heavy metal adsorbent.

Example 1 Polyethyleneimine (epoxy 5P) with a molecular weight of 1,800
-018, Japan Shokubai Chemical System) 5I with ion-exchanged water 95.
Coconut grain activated carbon (30 to 60 mesh, manufactured by Dai-Kan Kogyo Co., Ltd.) 20.0 # was added to the mixture, stirred at 43°C for 2 hours, separated from F, and thoroughly washed with ion-exchanged water. did.

The impregnation rate of polyethyleneimine is 1 due to the weight increase after drying.
It was 0% by weight.

Next, the obtained polyethyleneimine-impregnated carbon 22.0F was mixed with glycerin diglycidyl ether (Denacol BX-31
3. Nagase Sangyo) 0.50# and ion exchange water 100
The mixture was reacted at 60° C. for 2 hours while slowly stirring with g, and then cooled to 30° C. Next.

After adding 2.4 g of carbon disulfide and reacting at 40 to 43°C for 2 hours, adding 20% sodium hydroxide solution 209 and treating at 20 to 30°C for 3 hours, filtering, washing with water, and drying. An adsorbent of 6JF was obtained.

Based on the weight increase, the total impregnation rate was 28% by weight.

Example 2 Polyethyleneimine (Evomin 5P) with a molecular weight of 1,200
-012, Nippon Shokubai Chemical System) 3.0.9 was dissolved in 97FK ion-exchanged water, and coconut grain activated carbon (20-50
Metsushi, manufactured by Dai-Kan Kogyo) 20. Add OF.

After stirring at 30° C. for 2 hours, the mixture was separated from F and thoroughly washed with ion-exchanged water.

From the weight increase after drying, the impregnation rate of polyethyleneimine is
It was 5.5% by weight.

Next, the obtained polyethyleneimine-impregnated carbon 21. II! was slowly stirred with 0.26 F of glycerin triglycidyl ether and 100 I of ion-exchanged water.
After reacting at 50°C for 3 hours, the mixture was cooled to 30°C. Next, 1.23 g of carbon disulfide was added and reacted at 40 to 43°C for 2 hours, followed by a 20% sodium chloride aqueous solution 4019.
was added and treated at 20 to 30°C for 3 hours, separated by F, washed with water, and dried to obtain a 22.45' adsorbent.

Based on the weight increase, the total impregnation rate was 12% by weight.

Example 3 Polyethyleneimine with a molecular weight of 300 (Evomin 5P-0
03, Japan Shokubai Chemical System) 3. ! M' is ion-exchanged water 10
After adding 25.0 g of coconut grain activated carbon (30 to 60 mesh, manufactured by Dai-Kan Kogyo Co., Ltd.) and stirring at 30°C for 1 hour, F was separated and thoroughly washed with ion-exchanged water. .

Due to the weight increase after drying, the impregnation rate of polyethyleneimide/ is 1
It was 5% by weight.

Next, 28.8 g of the obtained polyethyleneimine-impregnated carbon was mixed with the reaction mixture obtained in Reference Example 1 and 100 I of ion-exchanged water.
After reacting with i at 70°C for 1 hour with slow stirring, the mixture was cooled to 30°C. Next.

Carbon disulfide 4.4 II and 20% sodium chloride solution 2
1. OII was added and treated at 50° C. for 2 hours, separated by F, washed with water, and dried to obtain a 34.5# adsorbent.

The weight increase and total impregnation rate was 38% by weight.

Comparative Example 1 5 g of polyethyleneimine (Evomin 5p-ois, Nippon Shokubai Chemical Co., Ltd.) with a molecular weight of t and soo was dissolved in 95 g of ion-exchanged water, and coconut grain activated carbon (30-60 mesh) 20.0F was added thereto. After stirring at 43° C. for 2 hours, the mixture was separated from F and thoroughly washed with ion-exchanged water.

The impregnation rate of polyethyleneimine is 1 due to the weight increase after drying.
It was 0% by weight.

Next, the obtained polyethyleneimine-impregnated carbon 22. Og was slowly stirred with 2.5 I of carbon disulfide and 100 g of ion-exchanged water, heated and stirred at 40°C for 1 hour and then at 85°C for 3 hours, separated from F, and thoroughly washed with ion-exchanged water. A 23.0 N adsorbent was obtained.

Based on the weight increase, the total impregnation rate was 15% by weight.

Example 4 xoytq7 to 50 mg of an aqueous solution containing concentrated mercury.

The heavy metal adsorbents manufactured in Examples 1 to 3 and the heavy metal adsorbents manufactured in Comparative Example 1 were each mixed at 0. Add II.

The contact was carried out at 30° C. for 1 hour while shaking.

As a result, the mercury concentration in the aqueous solution after treatment is shown in Table 1.

Note that the mercury concentration was measured by low-temperature vaporization atomic absorption spectrometry. It was. The composition of the mercury-containing aqueous solution was as follows.

(Hg: toIIv/z, NaC1: 5.OI
I/l, PH=6.0) Table 1 Comparative Example 2 10181/ to an aqueous solution containing mercury at a concentration of 50-.

Commercially available chelate resin for suction adsorption was 0.2 N in wet condition.
and coconut grain activated carbon (GP30-60') 0. I.J.
was added and contacted for 1 hour at 300°C with shaking.

As a result, the mercury concentration in the aqueous solution after treatment is shown in Table 2.

(Measurement of mercury concentration and composition are the same as in Example 4.) Table 2 From Example 4 and Comparative Example 2, the heavy metal adsorbent produced by the present invention has a higher concentration than the known chelate resin for mercury adsorption.
It is clear that the mercury adsorption capacity, especially the mercury adsorption rate, is extremely excellent.

Example 5. Comparative Example 3 The heavy metal adsorbents produced in Examples 1 to 3, the heavy metal adsorbents produced in Comparative Example 1, and coconut grain activated carbon were added to 50 d of an aqueous solution containing lead at a concentration of 10 μm, respectively. 11
and contact with shaking at 30° C. for 12 hours.

As a result, the lead concentration in the aqueous solution after treatment is shown in Table 3.

Note that the lead concentration was measured by atomic absorption spectrophotometry.

Further, the composition of the lead-containing aqueous solution is as follows.

2+ Pb: 10Q/L, NaC1: 5.01/L
, PH=7.0) Table 3 From the results shown in Table 3, the heavy metal adsorbent produced according to the present invention can treat lead at a low concentration of 1 - below the wastewater standard (1/l).

Example 6. Comparative Example 4 The heavy metal adsorbent manufactured in Example 1.2, the heavy metal adsorbent manufactured in Comparative Example 1, and a commercially available mercury chelate resin were mixed with an inner diameter of 9WI11! A φ glass column was filled with 6M in a wet state, and a mercury-containing solution was passed through it in a downward flow at a space velocity of 10.

The exchange capacity at 9 flow points was determined from the amount of liquid passed until the mercury concentration exceeded 5 my/l of o or oo after the liquid flow treatment.

The results are shown in Table 4.

c Hg2”: 2oowq/l, NaCl; 5
tvt, PH: 6.0) Table 4 Patent applicant Unitika Co., Ltd.

Claims (3)

[Claims] (1) A heavy metal adsorbent comprising activated carbon impregnated with a reaction product of water-soluble amines, a water-soluble epoxy crosslinking agent, and carbon disulfide or a salt thereof. (2) Impregnate activated carbon with water-soluble amines in the presence of water, react the impregnated water-soluble amines with a water-soluble epoxy crosslinking agent, and then treat with carbon disulfide or disulfide. Activated carbon, which is characterized by being treated with carbon and a base, and water-soluble amines. A method for producing a heavy metal adsorbent comprising impregnating a water-soluble epoxy crosslinking agent and a reaction product of carbon disulfide or a salt thereof. (3) A heavy metal adsorbent made by impregnating activated carbon with a reaction product of water-soluble amines, a water-soluble epoxy crosslinking agent, and carbon disulfide, or a salt thereof, is brought into contact with the mold metal solution. A method for adsorption treatment of a heavy metal solution, characterized by: