JPS63197554A - Preparation of anion adsorbent - Google Patents

Abstract

PURPOSE:To efficiently prepare an economical anion adsorbent, by impregnating a particulate substrate with a liquid mixture containing vinyl pyridine, a crosslinkable divinyl monomer or the like and, after evaporating a solvent, copolymerizing the adhered monomers in a gaseous phase. CONSTITUTION:At first, a required amount of vinyl pyridine, a crosslinkable divinyl monomer and a polymerization initiator are added to a low b.p. org. solvent to prepare a liquid mixture. Next, the liquid mixture is received in a reaction vessel and a particulate substrate, for example, a silica gel, alumina, natural zeolite or activated carbon is added to the liquid mixture to be impragnated therewith and, thereafter, the org. solvent is removed by a vacuum means. Subsequently, the vinyl pyridine and crosslinkable divinyl monomer adsorbed by the surface of the substrate are copolymerized in a gaseous phase by heating. By this coating method, the regulation of the adhesion amount of the monomers to the particulate substrate or a crosslinking degree becomes easy and manufacturing efficiency is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing an anion adsorbent. More specifically, the present invention.

Efficient production of anion adsorbents that have excellent mechanical strength, adsorption speed, and resistance to expansion and contraction, and are made by coating the surface of a granular substrate with a copolymer of vinylpyridine and a crosslinkable divinyl monomer. It's about how to do it.

Conventional technology In recent years, ion exchange resins have been widely used in various fields, such as water treatment and the separation and purification of amino acids and nucleic acid-related substances in the food field, and antibiotics in the pharmaceutical and biochemical fields. In the analytical chemistry field, it is used as a separation carrier for chromatography, etc., for decolorizing and desalting enzymes, proteins, etc.

These ion exchange resins are generally classified into strongly acidic cation exchange resins, weakly acidic cation exchange resins, strongly basic anion exchange resins, and weakly basic anion exchange resins, depending on the type of exchange group, physical structure, degree of crosslinking, etc. It can be roughly divided into four types.

By the way, among these ion exchange resins, those made of a copolymer of vinylpyridine and a crosslinkable divinyl monomer such as divinylbenzene are generally known as weakly basic anion exchange resins. However, this material is inferior in mechanical strength, adsorption speed, and resistance to expansion and contraction, and is not fully satisfactory in terms of durability, making it difficult to use it industrially as an anion adsorbent as it is. It has its drawbacks.

Therefore, the present inventors previously developed a (heavy) chromium adsorbent that is made by coating the surface of a fine powder base with a copolymer of vinyl pyridine and a crosslinkable divinyl monomer, as an anion adsorbent that has improved these drawbacks. He discovered an acid ion adsorbent and proposed a method for producing it (Japanese Patent Publication No. 52741/1983). In this method, vinyl pyridine and a crosslinkable divinyl monomer are catalytically adsorbed with steam onto a fine powder base supporting a polymerization initiator, and polymerization is carried out. The method is to cover it with However, although this method provides an adsorbent that has been improved to some extent from the above-mentioned drawbacks, it is difficult to control the amount of monomer adsorbed and the degree of crosslinking, and gas adsorption equipment is required, resulting in high costs. However, this method cannot necessarily be said to be a satisfactory method.

Problems to be Solved by the Invention Under these circumstances, the present invention has excellent mechanical strength, adsorption speed, resistance to expansion and contraction, and durability, and can be suitably used industrially. The object of this invention is to provide an extremely efficient and economically advantageous method for producing an anion adsorbent comprising a powdery substrate coated with the copolymer.

Means for Solving the Problems In order to achieve the above object, the inventors of the present invention have conducted extensive research, and as a result, impregnated a powdery substrate with a mixed solution consisting of various monomers, a polymerization initiator, and a low-boiling organic solvent. Afterwards, they discovered that the purpose could be achieved by evaporating the solvent and then copolymerizing the monomers attached to the surface of the substrate in the gas phase, and based on this knowledge, they completed the present invention. Ta.

That is, in the present invention, vinylpyridine, vinylpyridine,
After impregnating a mixed solution consisting of a crosslinkable divinyl monomer, a polymerization initiator, and a low boiling point organic solvent, the solvent is evaporated and then the vinylpyridine and crosslinkable divinyl monomer attached to the surface of the substrate are impregnated. Provided is a method for producing an anion adsorbent in which the surface of a powdery substrate is coated with a copolymer of vinylpyridine and a crosslinkable divinyl monomer, the method comprising copolymerizing the above in a gas phase. It is something to do.

The present invention will be explained in detail below.

The powdery substrate used in the method of the present invention is made of an inorganic or organic material with a large surface area, and examples of such materials include silica gel, synthetic zeolite,
Examples include those made of natural zeolites, molecular sieves, alumina, carbon black, activated carbon, cellulose, etc.

These substrates may be used alone or in combination of two or more.

Examples of the vinylpyridine used in the method of the present invention include 2-vinylpyridine and 4-vinylpyridine, which may be used alone or in combination of two or more.

Furthermore, examples of crosslinkable divinyl monomers include aromatic divinyl compounds such as divinylbenzene, divinyltoluene, and divinylnaphthalene, and aliphatic divinyl compounds such as ethylene glycol diacrylate and ethylene glycol dimethacrylate. These may be used alone or in combination of two or more. The ratio of this to the vinylpyridine is appropriately selected depending on the desired degree of crosslinking.

As the polymerization initiator used in the method of the present invention, any conventional radical initiator can be used, such as benzoyl peroxide, azobisisobutyronitrile, potassium persulfate, and the like. These polymerization initiators are usually used in an amount of 0.5 to 5% by weight compared to the use of vinylpyridine.

Examples of organic solvents include low-boiling compounds such as methanol, ethanol, acetone, and diethyl ether.

In the method of the present invention, first, required amounts of vinylpyridine, a crosslinkable divinyl monomer, and a polymerization initiator are added to the above-mentioned low-boiling organic solvent to prepare a mixed solution. There is no particular restriction on the solid content concentration of this liquid mixture. Next, the mixed solution is placed in a reaction container, and after adding and impregnating the powdery substrate into the reaction container, the organic solvent is removed by means such as reduced pressure, and then the container is sealed and heated. Vinylpyridine and the crosslinkable divinyl monomer adsorbed on the surface of the substrate are copolymerized in a gas phase. The polymerization temperature may be generally higher than the decomposition temperature of the polymerization initiator, and is generally selected within the range of 50 to 100°C under normal pressure. Polymerization may be carried out while the contents are kept stationary, or may be carried out while stirring or stirring.

The amount of vinylpyridine used in the present invention, c, the substrate 10
It is preferably 20 parts by weight or less per part of 0 weight.

If this amount exceeds 20ii parts, powdery substrates will adhere,
This is not preferable because it often aggregates and makes it impossible to obtain a uniform composite.

In this way, an anion adsorbent is obtained in which the surface of a granular substrate is coated with a copolymer of vinylpyridine and a crosslinkable divinyl monomer.

Effects of the Invention According to the method of the present invention, it is easy to adjust the amount of monomer adhering to a powdery substrate and the degree of crosslinking, and there is no need for gas adsorption equipment, etc., and it is extremely efficient and economically advantageous to form a powdery substrate. An anion adsorbent whose surface is coated with a copolymer of vinylpyridine and a crosslinkable divinyl monomer can be produced.

The anion adsorbent obtained by the method of the present invention not only has excellent mechanical strength and resistance to expansion and contraction, but also has an extremely fast adsorption rate for anions, and is suitable for industrial use in various fields.

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

Example 1 4-vinylpyridine5. oy, divinylbenzene 0.1
? , azobisisobutyronitrile 0.05F and diethyl ether 30- are placed in a reaction vessel, and 10
20 grams of silica gel sized to a size of 0 to 200 mesh was added and immersed. After that, diethyl ether was evaporated under reduced pressure at room temperature, then nitrogen gas was introduced to bring the pressure to normal pressure, and the mixture was left in a thermostat at 80°C for 5 hours to form 4-vinylpyridine and divinylbenzene on the silica gel surface. was polymerized.

After the reaction, the product was washed with hydrochloric acid and water, and then dried to obtain a product 23.9y in which the surface of the silica gel particles was substantially covered with the vinylpyridine-divinylbenzene copolymer. As a result of differential calorimetry analysis of the product, an exothermic peak and weight loss due to oxidative decomposition of the copolymer were observed at 280 to 750°C.
From this value, the copolymer content in the product was found to be 17.1% by weight.

The product has a dry volume of 1.3 cm1/r and a wet volume of 1.6 d.
/2, almost no swelling in water was observed, the shape remained unchanged even when vigorously stirred or shaken in water, and the mechanical strength was good.

The base exchange capacity of this product was measured by a conventional method and was found to be 1.01 meq/f.

Similar experiments were conducted using alumina, natural zeolite, and activated carbon instead of silica gel, and the results are summarized in the table below.

Comparative Example 1 4-vinylpyridine S, OF Tosivinylbenzene 0.
A copolymer was prepared by polymerizing No. 11 and sizing the particles into 100 to 200 meshes. This copolymer has a dry volume of 1.6i/
? At a wet volume of 51.4 i/V, it gelled and swelled in water, was destroyed by stirring or shaking, and its mechanical strength was extremely poor.

Example 2 Product obtained using silica gel in Example 1 1.0ffc
Potassium dichromate aqueous solution with r concentration 101!9/l 50
0 fnt, the solution OpH was adjusted while stirring at room temperature, the equilibrium pHk of the solution was measured after shaking for 1 day, the residual Orm degree in the solution was measured, and the removal rate was calculated from this value. . Similarly, po350 mg/t metaphosphoric acid and Cu 10 q/L 0u-EDTA
Product 1F was added to the complex aqueous solution 500- to determine the removal rate. The results are shown in Figure 1. A total of 90 to 100 of the Or203-, POi, and Ou-FiDTA complexes were removed from the product at around pH 3.

Example 3 The product 1.02 obtained using silica gel in Example 1 was
It was added to a potassium dichromate aqueous solution with an Or concentration of 10/l adjusted to H3, and the O in the solution was sampled at predetermined intervals while stirring at room temperature.
The r concentration was measured. The product is (! r 20 y f
Adsorption occurred quickly, and adsorption equilibrium was almost reached in 15 to 20 minutes. This change in Or concentration over time is shown by curve A in FIG.

Comparative Example 2 Copolymer 1 obtained in Comparative Example 1. The same operation as in Example 3 was carried out using θ2. Since the gel-like copolymer destroyed by stirring was dispersed in the sampled solution, the Or concentration in the solution was measured after centrifuging this solution. The results are shown as curve B in FIG. The adsorption rate was slow and adsorption equilibrium took a long time.

[Brief explanation of the drawing]

Figure 1 is a graph showing an example of the relationship between the pH and removal rate of an aqueous solution of Cr2O, PO; and Cu-EDTA complex using the adsorbent obtained by the method of the present invention. 207 is a graph showing an example of the relationship between the residual Or concentration in the solution and time when the adsorbent is added to the solution. 2 3 4 Evening 6 f: Hide, H Figure 1 0 10 20 30 710
”p:T-leap (#) Figure 2

Claims (1)

[Claims] 1. After impregnating a powdery substrate with a mixed solution consisting of vinyl pyridine, a crosslinkable divinyl monomer, a polymerization initiator, and a low-boiling organic solvent, the solvent is evaporated off, and then the vinyl adhering to the surface of the substrate is removed. The surface of a powdery substrate is coated with a copolymer of vinylpyridine and a crosslinkable divinyl monomer, characterized by copolymerizing pyridine and a crosslinkable divinyl monomer in a gas phase. Method for producing anion adsorbent.