JP2002361081A - Hydrophobic material adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbent which adsorbs hydrophobic materials, particularly hormone-like active substances, polycyclic aromatic hydrocarbons and volatile organic compounds with high efficiency and easily desorbs these. SOLUTION: The hydrophobic material adsorbent comprises a crosslinked polymer obtained by copolymerizing a hydrophobic non-crosslinkable monomer (e.g. methyl methacrylate or styrene) and a hydrophilic crosslinkable monomer (e.g. nonaethylene glycol dimethacrylate).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an adsorbent for adsorbing hydrophobic substances, particularly hormone-like substances, polycyclic aromatic hydrocarbons and volatile organic compounds, in a sample with high efficiency and easily desorbing them. About.

[0002]

2. Description of the Related Art Various kinds of hydrophobic harmful substances are contained in environmental samples such as environmental water including waste water, soil, and air. Generally, the initial concentration of these hydrophobic harmful substances in large amounts of environmental samples is low. However, while it is present in an environmental sample for a long period of time, it is highly concentrated due to low diffusivity such as the surface of a solid substance in the environmental sample or concentration in a living body, which has a great effect on ecosystems. Therefore, leaving them in a low concentration state in a large number of environmental samples is a serious problem.

[0003] Among these hydrophobic harmful substances, some of steroid hormones and chemical substances derived from the living body or synthesized into the environment exhibit hormone-like actions when taken into the living body. There is. These chemicals are called endocrine disrupting chemicals, and it has been found that even a very small amount has an adverse effect on the reproductive function of animals. These steroid hormones and hormone-like agents (hereinafter collectively referred to as hormone-like agents)
Since these substances are often derived from artificial discharges, it is necessary to efficiently remove these substances during the discharge treatment process.

[0004] On the other hand, volatile organic compounds such as trichlorethylene, which are used in large quantities in various industrial processes, are substances that are pointed out as carcinogens. It has been. Some of these volatile organic compounds are also used as construction materials due to their preservative effect, and there is a concern that they may adversely affect residents. In addition, polycyclic aromatic hydrocarbons such as benzopyrene are substances that are pointed out to be carcinogenic in exhaust gas from various household or industrial combustion devices, particularly in automobile exhaust, and are high in environmental air. The presence at concentration has been regarded as a problem. These substances also have significant direct effects on the human body, so their removal during the emission process,
Removal from the environment is required.

In general, inorganic adsorbents such as activated carbon, zeolite, and silica; and organic synthetic polymer adsorbents composed of synthetic polymers are used as adsorbents for adsorbing hydrophobic substances in various samples. . The above-mentioned inorganic adsorbent has a drawback that it is difficult to change the composition in accordance with the target substance because the constituent materials are limited. In addition, it has been pointed out that there are drawbacks such as difficulty in regeneration treatment, risk of ignition, and high cost. On the other hand, the organic synthetic polymer-based adsorbent has an advantage in that the material can be selected over a wide range, so that optimization according to the target substance is easy.

As a hydrophobic substance adsorbent composed of an organic synthetic polymer-based adsorbent, an adsorbent containing styrene or divinylbenzene as a main component is widely used. However, since these styrene or divinylbenzene-based adsorbents have strong hydrophobicity, it is difficult to desorb the adsorbed substance once adsorbed. Therefore, the adsorbed substance is desorbed and the target substance is measured or the adsorbent is re-used. It was difficult to use.

Recently, an adsorbent in which a hydrophilic group has been introduced into the styrene adsorbent has been proposed. Examples of such an adsorbent include, for example, an adsorbent comprising (1) a divinylbenzene-vinylpyrrolidone copolymer (U.S. Pat.
(2,521)); and (2) an adsorbent comprising a copolymer of divinylbenzene-polyhydric alcohol poly (meth) acrylate (JP-A-6-258203).

However, the adsorbent of the above (1) is insufficient in hydrophilicity because the content of the hydrophilic monomer is as low as 12 to 30 mol%, and the adsorbing ability of the adsorbed hydrophobic substance is low. There were drawbacks. The adsorbent of the above (2) is made hydrophilic by using a polyhydric alcohol poly (meth) acrylate ester which is more hydrophilic than divinylbenzene as a copolymerization component. ) Since the hydrophilicity of the acrylate itself was low, the resulting copolymer was low in hydrophilicity and the desorption ability was insufficient. In the adsorbents (1) and (2), divinylbenzene which is a crosslinkable monomer is used as a hydrophobic monomer. However, divinylbenzene has a very strong hydrophobicity. This is the main cause of the decrease in the desorption ability of the adsorbent. However, it is necessary to maintain a high degree of crosslinking in order to improve the mechanical strength of the adsorbent, and there is a limit in reducing the amount of divinylbenzene used.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional hydrophilic group-containing adsorbent, in particular, a decrease in desorption ability, and its object is to provide a hydrophobic substance, especially a hormone-like substance, An object of the present invention is to provide an adsorbent that adsorbs polycyclic aromatic hydrocarbons and volatile organic compounds with high efficiency and easily desorbs them.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for adsorbing a hydrophobic substance, comprising a crosslinked polymer obtained by copolymerizing a hydrophobic non-crosslinkable monomer and a hydrophilic crosslinkable monomer. Agent (hereinafter also simply referred to as an adsorbent).

Hereinafter, the present invention will be described in detail. (1) Hydrophobic non-crosslinkable monomer The hydrophobic non-crosslinkable monomer in the present invention is not particularly limited, and includes known hydrophobic monomers, for example, methyl (meth) acrylate, ethyl Alkyl (meth) acrylates such as (meth) acrylate; (meth) acrylic monomers such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate; aromatic monomers such as styrene and vinyltoluene; Can be In this specification, the expression (meth) acryl is a generic term for acryl and methacryl. The expression (meth) acrylate is a general term for acrylate and methacrylate.

(2) Hydrophilic crosslinkable monomer The hydrophilic crosslinkable monomer in the present invention is a monomer having at least one hydrophilic group and at least two polymerizable groups. The hydrophilic group is a known hydrophilic functional group, and its molecular weight and structure are not particularly limited. Of these,
Particularly preferred are a hydroxyl group, an epoxy group, an alkylene glycol group, an aldehyde group, a cyano group, an amino group and a nitrogen-containing heterocyclic group. A plurality or a plurality of these hydrophilic groups may be present in one molecule of the monomer.

The polymerizable group is not limited as long as it is a functional group capable of forming a polymer by a polymerization reaction, but a vinyl group is particularly preferable. It is necessary that at least two of these polymerizable groups exist in one molecule of the monomer.

Examples of the hydrophilic crosslinkable monomer include polyethylene glycol di (meth) acrylate represented by the following formula (1):

Embedded image (Wherein, R represents H or CH ₃ , n represents a number of 5 or more) polypropylene glycol di (meth) acrylate represented by the following formula (2):

Embedded image (Wherein, R is H or CH ₃ , m is a number of 8 or more, and —C ₃ H
₆ O— is —CH ₂ CH ₂ CH ₂ O— or —CH (C
H ₃₎ CH ₂ O-or an _{-CH 2 CH (CH 3) O-} ) and the like glycerin di (meth) acrylate.
A plurality of these may be used.

The amount of the hydrophilic crosslinkable monomer used depends on the type of the monomer used, the type of the hydrophobic non-crosslinkable monomer, and / or the properties of the substance to be adsorbed. As the amount decreases, the hydrophobicity increases and the desorption ability decreases as in the prior art, and when the amount increases, the hydrophilicity increases and the hydrophobic substance cannot be sufficiently adsorbed. Therefore, 100 parts by weight of the hydrophobic non-crosslinkable monomer 100 to 1000 parts by weight, more preferably 150 to 800 parts by weight.

(3) Polymerization reaction The adsorbent of the present invention comprises a crosslinked polymer obtained by copolymerizing the above-mentioned hydrophobic non-crosslinkable monomer and the above-mentioned hydrophilic crosslinkable monomer. The polymerization reaction is usually performed in the presence of a polymerization initiator, as a polymerization method, a known polymerization method,
For example, a method such as a suspension polymerization method, a dispersion polymerization method, and an emulsion polymerization method may be used. Among them, it is preferable to use a suspension polymerization method from the viewpoint of easy operation. For example, when the suspension polymerization method is used, a mixture of the hydrophobic non-crosslinkable monomer, the hydrophilic crosslinkable monomer, and the initiator is dispersed in an aqueous dispersion medium in which a water-soluble dispersant is dissolved. After the addition of an additive or the like, the polymerization reaction can be carried out by raising the temperature under a nitrogen atmosphere while stirring.

Known water-soluble dispersants can be used, for example, synthetic polymers such as polyvinyl alcohol and polyvinyl pyrrolidone; cellulose derivatives; water-soluble polymer compounds such as gelatin and starch; Inorganic salts such as apatite, calcium phosphate, calcium hydroxide and calcium carbonate; various surfactants and the like are used. Among these, water-soluble polymer compounds are preferable, and nonionic water-soluble polymers such as polyvinyl alcohol and polyvinylpyrrolidone are particularly preferable.

As the dispersion medium, water or a known organic solvent is used. Preferably, water or a mixture of water and a water-soluble organic solvent is used.

The polymerization initiator is not particularly limited, and a known water-soluble or oil-soluble radical polymerization initiator is used. Specific examples of the polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; cumene hydroperoxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, o-chlorobenzoyl. Peroxide, acetyl peroxide, t-butyl hydroperoxide, t-butyl peroxyacetate,
organic peroxides such as t-butylperoxyisobutyrate, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxide; 2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis (2-methyl Azo compounds such as butyronitrile) and azobiscyclohexanecarbonitrile. The amount of the polymerization initiator to be used is 0.1 to 100 parts by weight of a monomer mixture of the hydrophobic non-crosslinkable monomer and the hydrophilic crosslinkable monomer.
The amount is preferably from 0.5 to 4 parts by weight, more preferably from 0.08 to 3 parts by weight. If the amount of the polymerization initiator is less than 0.05 part by weight, the polymerization reaction may be insufficient or the polymerization may take a long time. Things may occur.

Furthermore, at the time of the above polymerization, if necessary,
Known additives may be added. As these additives, for example, a porosifying agent (phase separating agent) for converting the polymer into a porous body having a large pore size, a chain transfer agent, a pH adjusting agent, a specific gravity adjusting agent, and the like are used.

As the above-mentioned porous agent, for example, alcohols such as isoamyl alcohol and octanol, aliphatic hydrocarbons such as hexane, and aromatic hydrocarbons such as xylene and toluene are used.

The reaction conditions for suspension polymerization using the above materials are as follows:
The polymerization temperature is preferably from 20 to 100 ° C., and the reaction is preferably performed for 0.5 to 50 hours, although it varies depending on the monomer and the polymerization initiator used. After polymerization, the obtained crosslinked polymer is washed and dried to obtain the adsorbent of the present invention. Water and / or an organic solvent is used for washing, and it is usually necessary to wash a plurality of times. Further, preferably, washing is performed a plurality of times with a plurality of types of organic solvents. Although the organic solvent used for washing varies depending on the monomer used, for example, a known organic solvent such as alcohols such as methanol and ethanol; and acetone is used.

The adsorbent of the present invention can be prepared from the above crosslinked polymer as a raw material by a known molding method, for example, an injection molding method,
It can also be prepared by an extrusion molding method or a blow molding method.

(4) Physical Properties of Adsorbent The shape of the crosslinked polymer used in the adsorbent of the present invention is not particularly limited, and examples thereof include particles, fibers, and filters.
Any shape can be used as long as the sample can be in contact with a liquid or gas sample, but it is particularly preferable that the sample is in the form of particles. The porous structure is also not limited, and may have a micropore structure or a macropore structure as long as it is porous enough to maintain its shape under the use environment. Further, it may be a foam. In addition, the size of the adsorbent of the present invention is not particularly limited, and is appropriately selected depending on conditions at the time of use,
In the case of particles, the average particle size is preferably from 0.1 μm to 50 mm, more preferably from 1 μm to 20 mm. If the values deviate from these ranges, it becomes difficult to perform the work during measurement, wastewater treatment, or exhaust treatment. In particular, when the adsorbent of the present invention is used for pretreatment of a hydrophobic substance measurement, the average particle size is preferably 1 to 500 μm,
10 to 300 μm is more preferred. In addition, when used for removing hydrophobic substances from a large amount of sample, 100 μm
50 mm is preferred, and 500 μm to 20 mm is more preferred. The density of the adsorbent of the present invention is preferably 0.5 to 3.0, more preferably 0.7 to 2.0. If the ratio deviates from this range, the handleability at the time of use, in particular, the handleability at the time of processing a large amount of sample is reduced. Further, in special circumstances, the adsorbent may be a coated structure in which the crosslinked polymer forms a surface layer. In that case, the material of the core portion to be coated is not particularly limited, and is formed of a material having a strength enough to maintain its shape under the use environment, and is formed of a material which does not elute a hydrophobic substance outside. There is a need. The shape of the adsorbent in the case of the coated structure is not particularly limited, and may be any shape such as particulate, fibrous, or filter, which can be in contact with the sample liquid or gas.

(5) Hydrophobic Substance The “hydrophobic substance” as used in the present invention has a solubility in water of 10 g / hydrophobic substance contained in a sample liquid or gas.
L or less, especially 1 g / L or less. These hydrophobic substances include, for example, hormone-like substances, polycyclic aromatic hydrocarbons, and volatile organic compounds. Hormone-like substances include biologically-derived or synthetic steroid hormones, and substances that are reported to exhibit hormone-like effects or suspected hormone-like effects in vivo, and are substances called so-called endocrine disrupting chemicals Is also included. Examples of the hormone-like active substance include dioxins including coplanar PCB and brominated dioxin; polychlorinated biphenyls; alkylphenols such as 4-t-butylphenol, 4-n-heptylphenol, nonylphenol, and 4-t-octylphenol; Bisphenol A; 2,4-dichlorophenol; phthalic acid such as dicyclohexyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, diheptyl phthalate, di-n-butyl phthalate, diethyl phthalate, dimethyl phthalate Esters; di-2-ethylhexyl adipate; benzo (a) pyrene;
Aromatic compounds such as benzophenone, 4-nitrotoluene, styrene, styrene dimer and styrene trimer; estrogens such as estradiol, estrone and estriol; and pesticides such as DDT.
The polycyclic aromatic hydrocarbons include all known polycyclic aromatic hydrocarbons, and include, for example, pyrene, benzo (a) pyrene, benzanthracene, methylcholanthrene, fluorene, anthracene, phenanthrene, and benzofuran. Oranthene, 1-pyrenol; sulfur-containing hydrocarbons such as benzothiophene and dibenzothiophene; and nitrated hydrocarbons such as naphthalenedinitropyrene and nitropyrene. As the volatile organic compound, for example, hexane, heptane, octane, decane, 2, 2,
Aliphatic hydrocarbons such as 4-trimethylpentane and butadiene; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene and 1,3,5-trimethylbenzene; terpenes such as α-pinene and limonene; trichloroethylene; Halides such as tetrachloroethylene, trichloromethane, 1,1,1-trichloroethane, 1,2-dichloroethane, 1,2-dichloropropane, and tetrachloromethane; esters such as butyl acetate; and the like. Then, these hydrophobic substances can be targeted for adsorption.

The adsorbent of the present invention is suitably used particularly in the adsorption of a compound having a benzene skeleton. Specifically, for example, dioxins; polychlorinated biphenyls; phthalates; estrogens; endocrine disrupting chemicals such as alkylphenols; polycyclic aromatic compounds such as benzopyrene and anthracene; toluene, nitrotoluene, xylene, and benzene ,
And aromatic hydrocarbons such as styrene. In addition, it is also suitably used for adsorption of aliphatic hydrocarbons such as hexane, decane and butadiene; and halogenated hydrocarbons such as dichloromethane, trichloroethylene, dichloroethane and trichloroethane.

(6) Use form of hydrophobic substance adsorbent The adsorbent of the present invention efficiently adsorbs hydrophobic substances, particularly hormone-like substances, polycyclic aromatic hydrocarbons or volatile organic compounds, and Adsorbent that desorbs easily. Therefore, it can be beneficially used for all applications including the step of adsorbing a hydrophobic substance. For example, it can be suitably used as an adsorbent for solid phase extraction in pretreatment for measurement of a hydrophobic substance, or as an adsorbent for environmental purification to remove a hydrophobic substance in a sample. However, it is not limited to only these uses.

(7) Form of Sample to be Adsorbed The form of the sample containing the hydrophobic substance to be adsorbed by the adsorbent of the present invention is not particularly limited, and may be any of liquid, gas, and extract from solid. It may be.

[0029]

The cross-linked polymer used in the hydrophobic substance adsorbent of the present invention uses a hydrophilic cross-linkable monomer in order to maintain mechanical strength and maintain hydrophilicity for improving desorption ability. On the other hand, it is a polymer copolymerized using a non-crosslinkable hydrophobic monomer in order to make the adsorbent hydrophobic so as to improve the adsorptivity of the adsorbent. Therefore, it absorbs hydrophobic substances with high efficiency,
And it becomes an adsorbent which is easily desorbed.

[0030]

Examples of the present invention will be described below. (Preparation of adsorbent) Example 1 200 g of methyl methacrylate (hydrophobic non-crosslinkable monomer) and 200 g of nonaethylene glycol dimethacrylate (hydrophilic crosslinkable monomer) were added to benzoyl peroxide (polymerization initiator: 1.5 g (Kishida Chemical Co., Ltd.) was dissolved. The obtained monomer mixture was dispersed in 2500 mL of a 4% by weight aqueous solution of polyvinyl alcohol while stirring, and the temperature was raised to 80 ° C. under a nitrogen atmosphere. After a polymerization reaction at 80 ° C. for 12 hours, the content was washed three times with ion-exchanged water and once with acetone. After washing and drying, an adsorbent was obtained.

Example 2 Example 2 was repeated except that 200 g of styrene (hydrophobic non-crosslinkable monomer) was used instead of 200 g of methyl methacrylate (hydrophobic non-crosslinkable monomer) in Example 1. An adsorbent was prepared in the same manner as in Example 1.

Comparative Example 1 Benzoyl peroxide (polymerization initiator: manufactured by Kishida Chemical Co., Ltd.) was added to 200 g of divinylbenzene (hydrophobic crosslinkable monomer) and 200 g of styrene (hydrophobic noncrosslinkable monomer). 5 g were dissolved. The obtained monomer mixture solution was weighed at 2500 m with a 4% by weight aqueous solution of polyvinyl alcohol.
The resulting mixture was dispersed in L while stirring, and heated to 80 ° C. in a nitrogen atmosphere. After a polymerization reaction at 80 ° C. for 12 hours, the content was washed three times with ion-exchanged water and once with acetone. After washing and drying, an adsorbent was obtained.

Comparative Example 2 In place of 200 g of styrene (hydrophobic non-crosslinkable monomer) in Comparative Example 1, ethylene glycol dimethacrylate (hydrophobic crosslinkable monomer) was used.
An adsorbent was prepared in the same manner as in Comparative Example 1 except that 200 g was used.

Comparative Example 3 180 g of divinylbenzene (hydrophobic crosslinkable monomer) and 100 g of N-vinyl-2-pyrrolidone (hydrophilic non-crosslinkable monomer) were mixed with 250 g of toluene.
Was dissolved. In this solution, 1.0 g of benzoyl peroxide (polymerization initiator: manufactured by Kishida Chemical Co., Ltd.) was dissolved. The obtained monomer mixture was mixed with a 4% by weight aqueous solution of polyvinyl alcohol 2
Disperse the mixture in 500 mL with stirring.
The temperature was raised to 0 ° C. After a polymerization reaction at 80 ° C. for 24 hours, the contents were washed three times with ion-exchanged water, once with acetone, and four times with ethanol. After washing and drying, an adsorbent was obtained.

(Evaluation of Performance) With respect to the adsorbents obtained in the above Examples and Comparative Examples, adsorption performance and desorption performance of a hydrophobic substance were evaluated as follows. 0.1 g of the adsorbent obtained in each of the above Examples and Comparative Examples was packed in a polypropylene column (3 mL in capacity, with a polyethylene filter). Dioxin 1pg-T
Dioxin was adsorbed to the adsorbent by passing 1 L of the sample containing EQ / L. The passed aqueous solution was recovered, the amount of dioxin was measured by an official method (Japanese Industrial Standard K0312), the adsorption rate was obtained, and the results are shown in Table 1.

In the above column, tetrahydrofuran 1
The dioxin adsorbed on the adsorbent was desorbed by passing 0 mL of the liquid. The mixed solution that passed through the column was collected, and the amount of dioxin was measured in the same manner as above to determine the desorption rate. The results are shown in Table 1.

[0037]

[Table 1]

As a result, all of the adsorbents obtained in the examples had good adsorption and desorption rates, and dioxin in the sample was recovered with high efficiency. On the other hand, the adsorbent of the comparative example had a low desorption rate, and dioxin in the sample could not be sufficiently recovered. That is, it was found that the adsorbent of the comparative example, which is a conventional technique, was unsuitable as an adsorbent for pretreatment such as measurement of dioxins.

[0039]

Since the adsorbent of the present invention has the above-described constitution, it can accurately adsorb hydrophobic substances, particularly hormone-like substances, polycyclic aromatic hydrocarbons or volatile organic compounds in the sample, Furthermore, the hydrophobic substance once adsorbed can be easily desorbed by a washing operation with an organic solvent or the like. Therefore, the adsorbent of the present invention can be suitably used for measuring or removing low-concentration hydrophobic substances, especially hormone-like substances, polycyclic aromatic hydrocarbons or volatile organic compounds. In particular, it can be suitably used for a process for recovering a trace amount of a hydrophobic substance from a sample. In addition, the adsorbent of the present invention has high mechanical strength due to a high degree of cross-linking, and can be easily handled with little breakage or the like even in large-scale processing or repeated use.

Claims (1)

[Claims] 1. A hydrophobic substance adsorbent comprising a crosslinked polymer obtained by copolymerizing a hydrophobic non-crosslinkable monomer and a hydrophilic crosslinkable monomer.