JPS6054353B2 - Heavy metal collection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a vinyl pyridine monomer containing a part of the polymer is mixed with a solvent that dissolves the monomer and oligomer but does not dissolve the polymer, and the polymer is removed as an insoluble component. The present invention relates to a method for collecting heavy metals, which uses a polymer compound obtained by radical polymerization of a mixture of the monomer and divinylbenzene.

Recently, in connection with pollution prevention, there has been a need to separate heavy metals from wastewater in particular, and many proposals have been made for collection methods and several products are commercially available.

Wastewater generally contains very low concentrations of heavy metal ions that must be completely removed, so it must be made of a material with strong collection power, and it must also be used in coexistence with other harmless metal ions. Therefore, it is required to have extremely high collection selectivity.

In addition, for industrial implementation, it is desirable that the operation be as simple as possible, that the heavy metal collection cost be low, and that the amount of heavy metals adsorbed should be large.

From this point of view, each conventional method has its advantages and disadvantages, and there has been a strong desire to develop a more excellent method for collecting heavy metals. The inventors of the present invention have diligently investigated a heavy metal collection method that does not have these drawbacks, and have found that a crosslinked polymer having a vinylpyridine skeleton in the main chain or side chain is extremely excellent as a heavy metal collection material, and has patented it. After filing an application, the present invention was arrived at as a result of further detailed study.

That is, the present invention provides a mixture of a vinylpyridine monomer partially containing a vinylpyridine polymer with a solvent that dissolves the monomer and oligomer but not the polymer to remove the polymer, and divinylbenzene. The present invention relates to a method for collecting heavy metals characterized by using a polymer compound obtained by radical polymerization of. Polymer compounds containing vinylpyridines are used in many fields such as ion exchangers, latex, polymer aggregates, and reverse osmosis membranes, but they are more expensive than other monomers and are used in many fields. is limited.

In addition, one of the reasons why vinylpyridine monomers are more expensive than other monomers is that they are much more easily polymerized than other monomers, and the monomers must be purified by distillation before use. The heating at this time may further cause polymerization of vinylpyridines. Since there are almost no effective polymerization inhibitors available for vinylpyridines, it is a particularly important issue to effectively and inexpensively recover vinylpyridine monomers from polymer-containing vinylpyridines to produce polymer compounds. Ta. Therefore, the present inventors have developed a polymer compound obtained by radical polymerization of a mixture of a vinylpyridine monomer and divinylbenzene, which is obtained by adding a solvent that does not dissolve the polymer to a vinylpyridine monomer containing a vinylpyridine polymer to remove the polymer. The present invention was completed based on the discovery that the amount of heavy metals adsorbed can be significantly increased by using this method as a method for collecting heavy metals. Vinylpyridines used in the production of materials used in the heavy metal collection method of the present invention include, for example, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-
Examples include vinylpyridine, 3,5-divinylpyridine, 2-methyl-4-vinylpyridine, and the like.

Solvents used in the production of materials used in the heavy metal collection method of the present invention include vinylpyridine monomers and their dimers,
It dissolves oligomers such as trimers but does not dissolve polymers such as vinylpyridine.

A polymer has a higher molecular weight than these oligomers. These solvents include saturated aliphatic hydrocarbons having 5 or more carbon atoms such as isooctane, aromatic hydrocarbons such as benzene and toluene, and saturated alicyclic hydrocarbons having 6 or more carbon atoms such as cyclohexane or 4 carbon atoms. The above alcohols, oxanes, ethers, ketones,
Petroleum ether, ligroin, esters, etc. can be used.

As other solvents, it is possible to use monomers having ethylenically unsaturated groups.

As examples of these, monovinylidene monomers such as acrylic esters, styrene, vinyltoluene, etc., or polyvinylidene monomers such as divinylbenzene, divinyltoluene, divinylethylene, diaryl phthalate, etc. can be used. These solvents must be appropriately selected depending on the properties of the vinylpyridines. For example, in the case of monovinylpyridines, the alcohol must have 7 or more carbon atoms. Those having 4 to 6 carbon atoms cannot be used for this purpose because they also dissolve monovinylpyridine polymers. However, in the case of polyvinylpyridines such as divinylpyridine, the number of carbon atoms is 4 to 6.
It is also possible to achieve this objective without dissolving the polymer component. Further, it is necessary to use the solvent in an amount of 10% or more based on the vinyl pyridine partially containing the polymer. Divinylbenzene is used in an amount of 2 to 55% by weight based on the total amount of the raw monomer mixture.

Known polymerization methods such as bulk polymerization, suspension polymerization, and emulsion polymerization can be used as the polymerization method for producing the material used in the heavy metal collection method of the present invention. During polymerization, a catalyst is usually used to complete the reaction sufficiently, and such a catalyst may be appropriately selected from among those commonly used in the polymerization reaction of vinyl compounds, such as benzoyl peroxide, tertiary butyl, etc. Peroxide, lauroyl peroxide, azobisisobutyronitrile, etc. are used in an amount of 0.01 to 3% by weight based on the total amount of the monomer mixture.
Further, it is also possible to use a precipitant in combination with the polymerization method for producing the material used in the heavy metal collection method of the present invention.

Any precipitant may be used as long as it dissolves the monomer, does not dissolve the polymer, and does not participate in polymerization. Examples of these include those having 4 or more carbon atoms such as butanol, secondary butanol, 2-ethylhexanol, and decanol. Alcohols or saturated aliphatic hydrocarbons with 5 or more carbon atoms such as heptane and isooctane, benzene, toluene,
Aromatic hydrocarbons such as xylene and ethylbenzene, saturated alicyclic hydrocarbons having 6 or more carbon atoms such as cyclohexane, alkyl esters having 6 or more carbon atoms, and JP-B No. 46
It is soluble in monovinyl linear polymers as shown in Japanese Patent Publication No. 40431, drying oils as shown in Japanese Patent Publication No. 47-(8), or monomers as shown in Japanese Patent Publication No. 47-40315. An inert micelle-forming solubilizing agent that is insoluble in the copolymer. These precipitants are preferably used on a basis of 5 to 60% based on the total amount of the monomer mixture.

According to the invention, for example when carrying out suspension polymerization, it is desirable to add a suspension stabilizer to the reaction system in order to facilitate the reaction. Suspension stabilizers are arbitrarily selected from those commonly used in this type of reaction, such as polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose. Used are sodium polymethacrylate, sodium polyacrylate, calcium carbonate, calcium sulfate, ammonium salt of starch styrene maleic anhydride copolymer, bentonite, magnesium silicate, gelatin, and the like. Add more sodium chloride. During the polymerization reaction, the droplets of the monomer layer are made more uniform, making it easier to control the size range. Furthermore, when aqueous suspension polymerization is carried out, it has the effect of reducing the dissolution of the moimer in the water layer, and the amount of the moimer added is 5 to 3% by weight based on the water. Furthermore, 0.01 to 1% by weight is added to prevent polymerization of monomers dissolved in the aqueous layer.
It is desirable to carry out suspension polymerization by adding sodium nitrite. Suspension polymerization is carried out in an aqueous medium containing a suspension stabilizer, and the polymerization temperature is usually higher than the decomposition temperature of the radical initiator, for example in the range of 40 to 90°C under normal pressure. The material used in the heavy metal collection method proposed in the present invention contains oligomers such as dimers and trimers in the vinylpyridine monomer, so the structure is different from that obtained when the vinylpyridine monomer is used alone. It seems to be different compared to what is available.

However, the present inventors have discovered that although the total exchange capacity of the polymer compound is the same as when vinylpyridine monomers are used alone, the amount of heavy metals adsorbed is significantly increased.
It is not clear why the amount of heavy metal adsorption increases in the material of the present invention, but one factor is that it has a polymer structure in which several vinyl pyridine skeleton structures with one end in a free state are connected. This is presumed to be due to the fact that heavy metals are more likely to be taken into the body. For example, when adsorbing hexavalent chromium, 1.5 times as much hexavalent chromium is adsorbed as compared to the case of monomer alone. It is also presumed that by adding dimers and trimers of vinylpyridines, the material used in the heavy metal collection method of the present invention can be produced, and the amount of heavy metals adsorbed will also increase. Furthermore, by using a cross-linking agent, it has a crosslinked structure, and by removing polymeric vinylpyridines of oligomer or higher molecular weight with a solvent, the heat resistance and chemical resistance are inferior to methods using vinylpyridine alone. The present invention is characterized in that there is no such problem.

The heavy metals referred to in the present invention are metals of Group 1B, Group 1B, Group VB, Group 2B, and Group 2B of the periodic table, and a solution containing one or more of these metal compounds is to be collected.

The periodic table mentioned above is described on page 618 of Kagaku Daijiten 4, 1st edition, December 30, 1939, published by Kyoritsu Publishing Co., Ltd. Examples of these metals include the following:

Namely, salts of copper, silver, and gold and their complex salts (copper chloride, copper sulfate, silver nitrate, gold chloride, potassium silver cyanide, potassium silver titanide, potassium gold cyanide, chloroauric acid, sodium chloroaurate, etc.), Cadmium, mercury salts and their complex salts (cadmium chloride, mercury chloride, cadmium nitrate, cadmium cyanide, mercury potassium iodide, mercury potassium cyanide, etc.), vanadium, niobium, tantalum oxyacids and their salts (ammonium vanadate, chlorium vanadate, sodium vanadate, sodium niobate, etc.), chromium, molybdenum, tungsten oxyacids and their salts (
Potassium dichromate, sodium dichromate, chromic anhydride, ammonium molybdate, sodium molybdate, ammonium tungstate, potassium tungstate, etc.)
, manganese, technitium, rhenium oxyacids and their salts (sodium permanganate, potassium permanganate, magnesium permanganate, etc.). When the raw solution containing heavy metals is mainly water, the material proposed in the present invention for collecting heavy metals is preferably used in the form of an acid, particularly an inorganic mineral acid added thereto.

Examples include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc., and are appropriately selected depending on the properties of the heavy metal ions and coexisting ions to be collected. The collection capacity per unit weight of the material varies considerably depending on the type of acid added in advance, and the selection of the acid is important. Further, when the stock solution containing heavy metals is mainly non-aqueous, it is not necessary to carry out acid addition.

In very special cases, bases may also be added.

It is desirable that these factors be appropriately considered depending on the type of target heavy metal, the type of coexisting ions, and the type of stock solution containing the heavy metal.

As shown in the examples, the material obtained by such a method has extremely high selectivity, captures heavy metals at a surprising rate, and exhibits a high adsorption amount.

Examples will be described in more detail below, but the present invention is not limited thereto.

Reference Example 1 After leaving commercially available 4-vinylpyridine in a dark place at 30°C for one month, put 234y of 4-vinylpyridine in a 500cc beaker, add 58y of isooctane, stir well, and then lower the liquid level to When the floating insoluble 4-vinylpyridine polymer was removed, the polymer content was 30f.
Were present.

This yield was 87% as 4-vinylpyridine.
The molecular weight of the solution from which the polymer was removed was measured by the vapor pressure method and found to be 143. Reference Example 2 Commercially available 4-vinylpyridine was left in a dark place for one month at 30°C, and then placed in a 300cc Claisen flask for 250y.
Put it in and 5T! When distilled with NHy, 172.5 g of 4-vinylpyridine was obtained.

This was a 69% yield of 4-vinylpyridine. The molecular weight of this 4-vinylpyridine fraction was measured using a vapor pressure method and found to be 108. Reference Example 3 An oil layer having the composition shown in Table 1 was prepared using a mixture of 4-vinylpyridine and isooctane obtained in the same manner as in Reference Example 1.
Pour the aqueous layer into a 2e separable flask (with a cooler after stirring)
and stirred for 190 r''.P.m3O minutes at room temperature.

Thereafter, the temperature was raised to 80° C. in about 1 hour at the same stirring speed. After holding at 80°C for 2 hours, the temperature was raised to around 95°C and stirring was continued for 5 hours.

cooling,? After filtration, the obtained granular polymer was washed with methanol by Soxhlet extraction to obtain about 850 m of white opaque granules.
I got 1. The surface area of the obtained granules was 21d by BET method.
/g, and the total exchange capacity was 2.4 meq/ml. Reference Example 4 Approximately 830 ml of white opaque granules were obtained in the same manner as Reference Example 1 using the 4-vinylpyridine obtained in Reference Example 2 and using the oil layer and water layer having the composition shown in Table 2. .

When the obtained granules were compared with the granules obtained in Reference Example 3, the results were as shown in Table 3. Example 1 The resin obtained in Reference Example 3 was immersed in a 1NH2S04 aqueous solution for one day and night to make it into SO4 type, thoroughly washed with water, and adjusted to salt type. 50ml of the resin was prepared with an inner diameter of 15T! It was packed into an adsorption tower with a height of 60 Rml.

Chromic acid aqueous solution (CrJ3+500ppm, pH=3
．． 0) was passed downflow at a rate of 0.51 per hour.

The concentration of hexavalent chromium in the treated water was measured, and water flow was stopped when the concentration of hexavalent chromium reached 0.5 ppm (Cr4l&+
0.5 ppm is the limit of wastewater standards based on the Water Pollution Control Law. ). The amount of liquid passed was 6.3e, and the amount of CrO3 adsorbed was 121.2y per 1e of resin. Reference Example 5 The same procedure as in Example 1 was carried out except that the resin obtained in Reference Example 4 was used. As a result, the amount of liquid passed was 4.2 e and the amount of CrO3 adsorption was 80.8 y per 1 e of resin.

Examples 2 to 7 10 mt of the granules obtained in Reference Example 3 had an inner diameter of 10 r! r! ! The glass tube of No. i was filled with various metal salt aqueous solutions from the bottom at a rate of 120 ml/Hr, and the effluent was analyzed to obtain the results shown in Table 4.

Claims (1)

[Claims] 1. Vinylpyridine monomers containing a part of the polymer are mixed with a solvent that dissolves the monomer and oligomer but does not dissolve the polymer, and the polymer is removed as an insoluble component, and divinyl Group IB, Group IIB, Group VB, Group VIB of the periodic table, characterized by using a polymer compound obtained by radical polymerization of a mixture with benzene,
Method for collecting group VIIB metals. 2. The method according to claim 1, wherein the metal to be collected is hexavalent chromium. 3. The method according to claim 1, wherein the solvent is a saturated aliphatic hydrocarbon or a saturated alicyclic hydrocarbon having 6 or more carbon atoms. 4. The method according to claim 1, wherein the solvent is an alcohol having 4 or more carbon atoms. 5. The method according to claim 1, wherein the solvent is an aromatic hydrocarbon. 6. The method according to claim 1, wherein the solvent is another monomer copolymerizable with vinylpyridines and does not dissolve the vinylpyridine polymer. 7. The method according to claim 1, wherein the polymerization method is an aqueous suspension polymerization method or a bulk polymerization method. 8. The method according to claim 1, wherein the vinylpyridine monomer is 4-vinylpyridine. 9 Claim 1 in which the polymerization reaction is carried out in the presence of precipitate
The method described in section. 10. The method according to claim 9, wherein the precipitant is a saturated aliphatic hydrocarbon having 5 to 10 carbon atoms.