JPS6361998A - Manufacture of nuclear fuel element adsorbent for uranium, thorium, etc. using persimmon tannin as raw material - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (a) Industrial application field This invention is used for the recovery and removal of nuclear fuel elements such as uranium and thorium dissolved in the hydrosphere such as nuclear fuel manufacturing wastewater, mine water, and seawater. Therefore, it is related to the production of new adsorbents for nuclear fuel elements such as uranium and thorium using persimmon tannin as a raw material.

(0) Conventional technology Traditionally, as adsorbents for uranium, there have been inorganic adsorbents such as hydrous titanic acid and organic adsorbents such as chelate resins (amidoxime type, etc.). Since the system substance is originally fine particles, it must be molded and granulated when used as an adsorbent, and this molding and granulation operation reduces the adsorption rate and weakens the mechanical strength of the granulated product. There were drawbacks such as. On the other hand, organic adsorbents such as chelate resins have relatively high adsorption capacity, but their adsorption speed is slow and these adsorbents are extremely expensive, so they have drawbacks such as high recovery costs for the target metal. there were.

(c) Three points that the invention attempts to solve: This invention uses persimmon juice, which is one of the natural biological resources and can be made by hand at low cost, as a raw material, and has excellent adsorption ability for nuclear fuel elements such as uranium and thorium. The purpose of the present invention is to obtain an adsorbent with a high adsorption rate at a low cost and by a simple manufacturing method.

(d) Measures to solve the problem: Persimmon juice can usually be made manually in liquid or powder form, but since persimmon juice is extremely soluble in water, it cannot be used in its current form as an adsorbent for nuclear fuel elements such as uranium. Therefore, as shown in Examples, a water-insoluble gel adsorbent is produced by reacting persimmon juice with a polyaldehyde such as glutaraldehyde or glyoxal, or a mineral acid such as sulfuric acid.

(f) Effect The obtained persimmon astringent adsorbent exhibits extremely excellent uranium adsorption ability, and this substance can adsorb 1.37 g of uranium per part. This uranium adsorption value is the highest of any uranium adsorbent published to date.The reason why this material exhibits extremely high uranium adsorption ability is as follows.
This is thought to be due to the presence of significant amounts of polyphenol compounds such as tannins and flavonols in persimmon juice, and the large number of polyphenolic hydroxyl groups possessed by these compounds form chelated metals with uranium. In addition, by gelling persimmon juice, a 3D structure is created in which the polyphenolic hydroxyl group, which is a uranium adsorption functional group, can easily coordinate with uranium.
Moreover, since this gel is an extremely hydrophilic substance, it is thought that this substance exhibits extremely excellent uranium adsorption ability.

Furthermore, this persimmon astringent adsorbent has the following excellent adsorption properties.

(1) The uranium adsorption rate of this substance is extremely fast, reaching adsorption equilibrium in 2-4 hours. (2) Uranium adsorbed on this material can be easily desorbed with extremely dilute 0.01 N acid. (3) This material shows no deterioration in its uranium adsorption ability and can be repeatedly adsorbed and desorbed.
(4) Mn, Co, Ni, Zn.

The adsorption amount of metal ions from a mixed solution containing Cu, Cd, and U is in the following order: U>>(u>other metals, and this material exhibits a high selective adsorption ability for uranium. (5) This material has a high selective adsorption ability for uranium. Furthermore, as shown in the examples, it also exhibits high adsorption capacity for thorium.

(Book) Example (Example 1) To 8 parts of liquid persimmon astringent (polyphenol content 4.0 $), 25
Two parts of χ geltalaldehyde aqueous solution was added, and the mixture was allowed to stand for 12 hours to form a gel, thereby obtaining a persimmon astringent adsorbent. 5.0 tsg of the obtained adsorbent was added to a 10 ppm uranium solution (pH 6).
100% of uranium could be recovered by contacting with 200 ml for 1 hour while stirring while closed.

Further, by contacting 25 mg of this adsorbent with 500 ml of waste water (pH 8) containing 46 ρp- of uranium for 1 hour, 97 X of uranium could be recovered. In addition, 13.8 lag of this adsorbent was added to 4 x 10-”
M) By contacting with 100 I+ of lithium solution (pH 3) for 1 hour, 95X of thorium could be recovered.

(Example 2) Liquid persimmon astringent 1001 used in Example 1 was mixed with 6NH2SO
The adsorbent was obtained by adding 41 L of the adsorbent to 41 L and leaving it overnight, then filtering and washing with water.

By contacting 1.8 mg of this adsorbent with 100 ml of a 10 ppm uranium solution (pH 6) for 1 hour, 91X uranium could be recovered.

(Example 3) 1 part of 40X glyoxal solution was added to 9 parts of liquid persimmon astringent, and the mixture was left to stand for 12 hours to obtain a gel-like persimmon astringent adsorbent.

(g) Effects of the invention As mentioned above, this substance exhibits an extremely high adsorption capacity for nuclear fuel elements such as uranium and thorium, and can be produced at low cost and with simple operations. Also,
Because of its excellent physical properties, it can be used to remove nuclear fuel elements such as uranium and thorium contained in nuclear fuel refining wastewater, nuclear fuel processing wastewater, mine water, phosphoric acid liquid, seawater, etc., using either the column method or the batch method. can be efficiently collected and removed.

Claims (1)

[Claims] A method for producing an adsorbent for nuclear fuel elements such as uranium and thorium, which comprises reacting persimmon tannin with a polyaldehyde such as glutaraldehyde or a mineral acid such as sulfuric acid.