JPS58150434A - Heavy metal adsorbent and preparation thereof - Google Patents

Abstract

PURPOSE:To enhance adsorbing capacity of a heavy metal adsorbent prepared by adding and depositing a reaction product of polyethylene imine and carbon disulfide to activated carbon, to mercury to a large extent, by adjusting an adding and depositing ratio of the heavy metal adsorbent to activated carbon within a specific range. CONSTITUTION:Activated carbon is treated with polyethylene imine with M.W. of 600-6,000 and carbon disulfide in the presence of water and a reaction product of polyethylene imine and carbon disulfide is added to and deposited on the activated carbon to prepare a heavy metal adsorbent. In this case, about 8.5-20wt% on the basis of activated carbon of polyethylene imine is added to and deposited on activated carbon at first and the polyethylene imine added and deposited activated carbon is thereafter treated with carbon disulfide so as to adjust the total of adding and depositing amount of about 9-30wt% on the basis of activated carbon. As the result, an adsorbent having high selectivity, total exchange capacity and flow-through exchange capacity especially to mercury and long life is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heavy metal adsorbent prepared by treating activated carbon with /IJ ethyleneimine and carbon disulfide, and a method for producing the same.

Chelating ion-exchange resins are highly regarded as effective for adsorption and removal of heavy metals in wastewater, as environmental pollution caused by heavy metal ions contained in industrial wastewater has become a social issue. In particular, chelating ion exchange resins based on phenol/aldet resins or styrene resins and having chelate F functional groups such as imino V acetic acid, thiourea, and dithiocarba phosphate have been put into practical use as effective heat treatment agents. ing. However, when adsorbing and removing mercury, which is particularly harmful to the human body, these resins have a low adsorption speed, so if the tank is filled with excess liquid, high-speed processing will significantly reduce the adsorption capacity. Also, it is not suitable for treating a large amount of wastewater containing R+.

These chelating ion exchange resins
) and cannot adsorb and remove organic mercury and mercury at all, so it is not satisfactory as a treatment for industrial wastewater, research, and laboratory wastewater that contains mercury in various forms. There is still room for further improvement.

On the other hand, 9-granular activated carbon is used to treat heavy metals and organic matter in wastewater to compensate for the above drawbacks, but it generally has poor selectivity for heavy metal ions, especially mercury ions, and has a low adsorption capacity at low concentrations. Moreover, since it is susceptible to the influence of pH 1 co-loading, it is difficult to use in practice. As a solution to this.

Special Public Showa 5! S-22554 newsletter, special meeting 1984-84
Publication No. 74 etc. c + *, thiourea, thiosemicarba v
Adsorbents in which sulfur-containing amino compounds such as carbon dioxide and thioacetamide are supported on activated carbon, and adsorbents in which sulfur-containing amino acids are supported on activated carbon together with hydrohalic acid are in operation.

However, since thiosemica pazides are generally easily soluble in water, when used to remove heavy metal ions from an aqueous solution, there is a top μ such as some of the thiosemica pazides being eluted.
The problem has not necessarily been solved.Furthermore, when actually filling a column or the like to process water containing heavy metal ions, consideration must be given to the contact area of the adsorbent with water, adsorption capacity, mechanical strength, etc. Currently, there are many P1 points, and an economical and practical adsorbent has not yet been obtained.

As a result of intensive research to resolve this issue, the present applicant found that treating activated carbon with a water-soluble amine and carbon disulfide is an extremely simple and economical method that can be used to remove water after washing with water (after washing in large amounts of water). ) has been found to be able to obtain a heavy metal ion adsorbent with almost no decrease in adsorption capacity, and the obtained adsorbent can also absorb heavy metal ions.

In particular, it has excellent selectivity and adsorption capacity for mercury ions,
In addition, we discovered that the adsorbent has excellent contribution, and filed a patent application (Japanese Patent Laid-Open No. 55-159835). is the exchange capacity for 9 heavy metals, especially mercury,
In other words, the total exchange amount and the flow point intersection amount were not completely satisfactory.

Therefore, as a result of further intensive research to improve this point, the inventors of the present invention found that the carbon wetting rate for activated carbon was
The present inventors have discovered that when activated carbon is treated with 49-ethylene imine and carbon disulfide while adjusting the ac, the total exchange capacity for heavy metals, especially mercury, and the through-flow point exchange volume can be greatly improved. .

That is, the present invention provides a heavy metal adsorbent which is prepared by treating activated carbon with I9 ethyleneimine and carbon disulfide in the presence of water to impregnate the activated carbon with a reaction product of polyethyleneimine and carbon disulfide, in which the amount of impregnation is smaller than that of the activated carbon. A heavy metal adsorbent and activated carbon characterized in that the amount of the heavy metal adsorbent is about 9 to 50% by weight, and activated carbon is treated with polyethyleneimine and carbon disulfide in the presence of water to form a reaction product of polyethyleneimine and carbon disulfide on the activated carbon. When producing a heavy metal adsorbent, first impregnate activated carbon with polyethyleneimine, which is about 8.5 to 20 g6 by weight, and then the total impregnated amount is about 9 to SO weight to activated carbon. *This is a method for producing a heavy metal adsorbent, characterized by treating it with carbon disulfide so that it becomes C.

The adsorbent of the present invention has excellent total exchange capacity and flow-through point exchange capacity for single heavy metals, especially mercury.

If the amount of the reaction product of polyethyleneimine and carbon disulfide impregnated is less than about 9% by weight based on activated carbon.

The adsorption effect by the ligand is not sufficient, and only surface modification of activated carbon results in a product with a small total exchange capacity for heavy metals, especially mercury.Moreover, when the total exchange capacity for mercury exceeds about 30%, the pores of activated carbon This decreases the specific surface area of activated carbon and significantly reduces the adsorption effect of microzea on activated carbon, making it impossible to obtain a sufficient adsorption capacity. In particular, about 10 to 25% by weight of the adsorbent of the present invention based on activated carbon.
Preferably, it is attached.

The adsorbent of the present invention is one in which a reaction product of polyethyleneimine and carbon disulfide is impregnated, but unreacted polyethyleneimine or carbon disulfide may be impregnated therein.

In order to obtain the adsorbent of the present invention, it is desirable to maintain the molecular weight and concentration of polyethyleneimine and the charge ratio (bath ratio) of activated carbon and polyethyleneimine (1 reaction temperature) within predetermined ranges. As a method, polyethyleneimine is impregnated onto activated carbon in an amount of approximately 8.5 to 20% by weight based on the activated carbon. At that time, if the amount of d+2 lyethyleneimine impregnated is about 8.5% by weight of the activated carbon, the adsorption effect by the ligand will not be sufficient and the activated carbon will only be surface-modified. Only a small exchange capacity can be obtained, and if it exceeds about 20% by weight, the pore volume and specific surface area of the activated carbon will become small, and the adsorption effect by the micropores of the activated carbon will be drastically reduced.
- Sufficient adsorption capacity cannot be obtained.

The molecular weight of the polyethyleneimine used in the present invention is preferably 600 to 6,000.
If the molecular weight is smaller than 9m, adhesion to 9m is easy, but this is not preferable because it is within the range where elution into water occurs during absorption, and if the molecular weight exceeds 6,000, the impregnation rate decreases to about 8.0m.
This is not preferred because it tends to be difficult to adjust the content to 5 to 20% by weight.

The aqueous solution of polyethyleneimine is preferably 2 to 20% by weight, particularly preferably 3 to 15% by weight. When the concentration of polyethyleneimine is less than 2%, about 8.5~
It is not preferable because it tends to be difficult to impregnate 20% by weight, and if it exceeds 20% by weight, the viscosity of the aqueous solution increases and not only does it tend to be difficult to separate and wash with water, but also the polyethylene that is recovered once. The amount of imine becomes large, which is economically unfavorable.

In addition, the charging ratio of activated carbon and polyethyleneimine aqueous solution also affects the impregnation rate, and it is preferable to set the ratio by weight to 1:3 to 1:10.If the bath ratio is less than 1:3, the target impregnation rate may be 1:10 tends to be difficult to obtain.
If it exceeds this amount, it is not economically preferable because a large amount of impregnating treatment cannot be carried out.

Furthermore, the temperature at which polyethyleneimine is impregnated onto activated carbon is preferably 10C to 901C.If the temperature is lower than 10C or higher than 90C, it tends to be difficult to obtain the desired impregnation rate, so it is preferable. do not have.

The polyethyleneimine-impregnated carbon obtained in this way is activated carbon in which about 8.5 to 20% by weight of polyethyleneimine has been adsorbed, and the unadsorbed polyethyleneimine aqueous solution is separated by solid-liquid separation. It is preferable to thoroughly wash with water to remove the polyethyleneimine adhering to the surface.Also, the solid-liquid separated polyethyleneimine aqueous solution can be used repeatedly as many times as the concentration is adjusted. Available for use.

Next, in the second stage, the polyethyleneimine-impregnated carbon obtained above and carbon disulfide are treated, but during the treatment,
It is preferable to treat at 40C to 100C with *g of water. If the temperature is lower than 40C, the cross-linking three-dimensional reaction will not proceed sufficiently, so not only will it not be possible to form a thiocarbohydrazide structure, but it will also elute into ice. This is not preferable because it tends to increase the amount of carbon disulfide added.The amount of carbon disulfide to be added is 0.2 to 1 equivalent of primary and #f secondary amino groups of polyethyleneimine coated with activated carbon. 2-1
．． It is preferable to use an amount of 1@. If the amount is less than 0.2 equivalent, not only will the cross-linking three-dimensional reaction not proceed sufficiently and elution into water will tend to increase, but also the adsorption capacity for mercury will tend to decrease, and the amount of carbon disulfide added will decrease. If the amount exceeds 1.1 equivalent, the excess carbon disulfide will be adsorbed onto the activated carbon, resulting in a gummy odor and will tend to lower the pH, which is not preferable.

The activated carbon used in the present invention may be any type of activated carbon, but it is particularly preferable to use carbon activated by steam with Yarn V-shell carbon. Also, what is the particle size of activated carbon?

It is an important factor that controls the liquid flow rate and adsorption amount, and is 10 to 80.
A mesh, preferably 20 to 60 mesh, is used.

The adsorbent thus obtained is mercury (organic mercury, :I
rhoidal mercury), steel, cadmium, #1. It has a high selective adsorption property for heavy metals such as gold, especially mercury, and has excellent total exchange capacity and flow-through salt exchange capacity, so it can be used in the same way as ordinary chelating ion exchange resins.

This can be removed by contacting with a water-containing S solution. The contact method includes a batch method in which the adsorbent is simply mixed with a solution and stirred, and a cup method in which the adsorbent is filled in a cup and the liquid is passed through it, but the cuff method is generally used. The temperature of the heavy metal solution at that time is 45 to 1.00'
c is suitable, and a contact time of 4 to 8 hours is suitable.

According to the present invention, it is possible to obtain a heavy metal adsorbent in which the adsorption capacity after washing with water (after washing with a large amount of water) hardly decreases by a very simple and convenient method, and the obtained adsorbent has high selectivity and adsorption capacity (total exchange capacity and flow-through salt exchange capacity) for heavy metals such as mercury, steel, cadmium, silver and gold, and in particular for mercury, and is also excellent for blue gold as an adsorbent.

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

Fruit 11 Polyethyleneimine with a molecular weight of 1,200 (Evomin 8P
-012, Nippon Shokubai Kagaku II) 101 with ion-exchanged water 9
Coconut shell activated carbon (20-50 methV)
(manufactured by Daiichi Carbon Industry Co., Ltd.) 20. After adding Of and stirring at 30°C for 2 hours, the mixture was filtered and thoroughly washed with ion-exchanged water. Based on the weight increase after drying, the impregnation rate of polyethyleneimine was 15% by weight.

Next, the obtained polyethyleneimine impregnation*23. Of was slowly stirred with 2.6 g of carbon disulfide and 100% of ion-exchanged water, heated at 40°C for 1 hour, further heated at 75°C for 4 hours.
After continuing to heat and stir for a period of time, the mixture was filtered and thoroughly washed with ion-exchanged water to obtain an adsorbent.

The total impregnation rate (calculated from the weight increase) of the adsorbent thus obtained was 23% by weight.

01B, 8 catalyst chemistry 91) 51F with ion exchange water 95
9 and added coconut shell activated carbon (30 to 60 ml, manufactured by Dai-Kaban Kogyo) 20. After adding Of and stirring at 45C' for 2 hours, the mixture was filtered and thoroughly washed with ion-exchanged water. Based on the weight increase after drying, the impregnation rate of polyethyleneimine was 10% by weight.

Next, the obtained polyethyleneimine-impregnated *22.09 was slowly stirred with 2.5-carbon disulfide and 100 f of ion-exchanged water, and 4. After heating and stirring was continued for 1 hour at QC and further for S hours at 85° C., the mixture was filtered and thoroughly washed with ion-exchanged water to obtain an adsorbent.

The total impregnation rate of the adsorbent thus obtained was over 151%.

Comparative Example 1 Meliethyleneimine aqueous solution with a molecular weight of 70.000 and a concentration of 30% by weight (Evomin P-10001 Nippon Shokubai Kagaku $
Dissolve 10f in 90°C of ion-exchanged water, add 20.09ml of coconut shell activated carbon (20-50V), stir at 50C for 2 hours, filter, and dissolve in ion-exchanged water. Washed thoroughly. Based on the weight increase after drying, the impregnation rate of polyethyleneimine was 6.0% by weight.

Next TC4 impregnated polyethyleneimine * 20.6
f was slowly stirred with 1.0 g of carbon disulfide and ion-exchanged water 1009, heated and stirred at 40°C for 1 hour and then at 90°C for 4 hours, filtered, and thoroughly washed with ion-exchanged water. An adsorbent was obtained.

The total impregnation rate of the adsorbent thus obtained was 4.5% by weight.

Comparative Example 2 Polyethyleneimine with a molecular weight of 500 (Epomin SP-
003, manufactured by Nippon Shokubai Chemical) 30g of ion-exchanged water 709
Coconut shell activated carbon (30 to 60 ml,
Daiichi Carbon Industry @ ) 20. Add Of and S at 30℃
After stirring for an hour, the mixture was filtered and thoroughly washed with ion-exchanged water. 49 m of ethyleneimine from the weight increase after drying
The adhesion rate was 27% by weight.

Next, the obtained polyethyleneimine-impregnated carbon (25.49 g) was slowly stirred with 9.5 g of carbon disulfide and 1001 F of ion-exchanged water, heated and stirred at 50°C for 1 hour and then at 75°C for 4 hours, and then filtered. The adsorbent was then thoroughly washed with ion-exchanged water to obtain an adsorbent.

The total impregnation rate of the adsorbent thus obtained was 40% by weight.

Reference Examples 1 to 2 The adsorbents obtained in Examples 1 to 2 and Comparative Examples 1 to 2 and the raw material YaV Activation Hiro were each dried at a concentration of 0.10 fI.
I sold it, immersed it in 505 g of a low concentration mercury-containing aqueous solution, and
The lateral mercury concentration after immersion at 0° C. for 12 hours was measured by low-temperature vaporization reduction atomic absorption spectrometry, and the results are shown in Table 1.

The composition of the mercury-containing water $11 is as follows.

(Hg Kano, s 10#II/j, NaC1159/1
．． pH-6) Table 1 Reference Examples 3-4! 11!11911-2 and the adsorbent obtained in Comparative Example 1,
Each dry line was volatilized at 0.109, immersed in a highly concentrated mercury-containing aqueous solution at 50 mC, and the remaining mercury concentration after immersion at 60°C for 24 hours was measured by chelate titration to determine the total amount exchanged.

The results are shown in Table 2.

The composition of the mercury-containing aqueous solution is as follows*
(Hg Kano i1,000 da/1. NaC1 trial 59/1.
pH-6) Table 2 Reference Example 5 The adsorbents obtained in Example 1 and Comparative Example 1 were each filled as a wet resin into a gafskhum with an internal diameter of 9 cm, and
A mercury-containing liquid was passed through the chamber at a space velocity of 5 through a downward flow.

Flow until the mercury concentration in the flow-through exceeds 5 ppb.
□Find the liquid volume and show the exchange capacity at one flow point in Table-5.

The composition of the mercury-containing liquid is as follows.

(Hg” Judgment 200*/j, NaC1s 5t/1
．． pH6) Table 3

Claims (1)

[Scope of Claims] (1) A heavy metal WI4I4 adhesive obtained by treating activated carbon with polyethyleneimine and carbon disulfide in the presence of books to impregnate the activated carbon with a reaction product of polyethyleneimine and carbon disulfide, A heavy metal adsorbent characterized in that the amount of impregnation is about 9 to 30 direct weight superior to that of activated carbon. (!) The adsorbent according to claim 1, wherein about 9 to 30% by weight is greater than about 10 to 25% by weight. (3) When producing a heavy metal adsorbent in which activated carbon is treated with polyethyleneimine and carbon disulfide in the presence of water to impregnate the reaction product of polyethyleneimine and carbon disulfide to a high degree of activity, first the activated carbon W -gv ethyleneimine 0
Approximately 8.5 to 20 weight for w4 activated carbon *@ After betting,
A method for manufacturing a heavy metal adsorbent, characterized in that it is treated with carbon disulfide so that the total amount of impregnation is about 9 to 30 units per activated carbon (4) Polyethyleneimine is 600 to 30 units
The manufacturing method according to claim 3, wherein the polyethyleneimine has a molecular weight of 6,000.