LT4725B - Sorbent for iodine and method for the preparation thereof - Google Patents

Abstract

The invention concerns chemistry engineering and may be used in certain technologies for fixing and neutralizing iodine, eliminating it from gas or airflow exhaust absorbers.A hydrothermal processing resistant iodine sorbent is extracted from absorbent carbon and iodine acceptor is extracted from polydimethyl diallyl ammonium iodide. Granular or fibred absorbent carbon can also be used. Iodine sorbent is extracted through impregnating absorbent carbon with a water polymethyl diallyl ammonium iodide solution of 1-4%.

Description

The invention relates to the field of chemical engineering and can be used in special iodine-binding and decontamination technologies. This includes removing it from the gas or air stream in the absorbers.

Activated charcoal is known to bind iodine in emissions [cf. kn .: Filtering from Abluft aus Kemtechnischen Anlagen und Isotopenlaboratorien / von

J. G. Wilhelm. Schriftenreihe Reaktorsicherheit und Strahlenschutz.-BMU, 1998, 376 s .; Ta300HHCTKa h κοΗτροπΒ ra3OBbix BBidpocoB A3C / H.E.HaxyTHH, /TB.Oukhh, H.M.CMnpHOBa h /ip..- M.: SHeproaioMinaai, 1983- 24 c.]. Activated carbon is impregnated with a variety of water-soluble organic and inorganic materials, hexamethylenetetramine, to increase the sorption of iodine. TS: TY 6-16-3028-87], triethylenediamine [cf. kn .: Ta3oomiCTKa h KOHTporib ra30Bbix BbiopocoB A3C / H.E.HaxyniH, J.B.Oukhh, H.M.CMnpHOBa n ap ..- M.: 3HeproaTOMii3 ^ aT, 1983.-24c.], metal iodides [see. kn. H.Deubner, K.Gerlach. Parametrische Untersuchungen zur Abscheidung von Methljodid an einer KJimpemierten Aktivkohle KfK 3746, Forschungscentrum Karlsruhe, 1984 and TS: TY

6-16-3028-87], silver nitrate.

Their disadvantage is that hexamethylenetetramine and triethylenediamine are toxic and flammable compounds [cf. kn .: npeøenbHO aonycTHMbie KOHueHTpamm XHMHHecKHX BeiųecTB b OKpy / Kaiomeii cpene / Γ.Ε. EecnaMHTHiiKOBa, K) .A. ΚροτοΒ.-Jl: Χημηλ, 1985]. This must be taken into account during operation of the iodine absorbers, especially during charging.

Non-toxic metal iodides are commonly used. Poly (dimethyldiallyl) ammonium iodide (PDMDAAJ), a low-soluble but high-sorption iodine non-flammable and non-toxic polymer, is known. Lithuanian Pat. No. 4497, TPK C08F 126 / 02,1999]. In 20 ° C water, PDMDAAJ dissolves in 0.5 g / l, 95 ° C - 65 g / l. Thus, the solubility of PDMDAAJ in water at elevated temperatures is also significantly increased.

A major disadvantage of all of the above iodine sorbents is the low resistance to hydrothermal effects due to the water solubility of the iodine acceptors used. When vapors get into the absorber or other humidity and temperature rise, the iodine acceptors can migrate and be washed off with activated water from the condensing water.

Closest to the present invention are potassium iodide (KI) impregnated activated carbon for use in practice. TS: ΊΎ 6-16-3028-87 et al .: Filterung von Abluft aus Kemtechnischen Anlagen und Isotopenlaboratorien / von J.Gavilhelm. Schriftenreihe Reaktorsicherheit und Strahlenschutz.-BMU, 1998, 376 s]. Potassium iodide content in sorbent is 1-2%.

It is an object of the present invention to provide an iodine sorbent which is more resistant to hydrothermal effects, i. multiple treatments with hot (85-95 ° C) water do not wash the iodine acceptor. Such an iodine acceptor is immobilized on activated carbon polydimethyldiallyl ammonium iodide.

This objective is achieved by impregnating the activated carbon with an aqueous solution of 1-4% PDMDAAJ and drying. The thus obtained granular impregnated activated carbon iodine sorbent has from 1 to 4% iodine acceptor and the fibrous impregnated activated carbon iodine sorbent contains 5% PDMDAAJ.

Table 1 provides data on various iodine sorbents, and Table 2 compares the hydrothermal resistance of iodine sorbents obtained by the prototype and the proposed process. As can be seen from the data in Table 1, iodine acceptors increase iodine binding by impregnated activated carbon. The sorption power of the impregnated activated carbon iodine depends on the activated carbon used for impregnation, the acceptor and its content in the sorbent. Immobilization of activated carbon on the same amount of PDMDAAJ as the prototype used potassium iodide (Table 1, Nos. 2, 3) improves its sorption properties. The sorption power of impregnated PDMDAAJ-activated carbons increases with increasing PDMDAAJ content in the sorbent (Table 1, # 3-5). However, we cannot impregnate activated carbon with higher concentrations of PDMDAAJ solutions due to the limited water solubility of the polymer). Lithuanian Pat. No. 4497, TPK C08F, 1999j. The fibrous activated carbon has a higher iodine sorption capacity due to its higher active surface area than granular. They are treated with PDMDAAJ solution (Table 1, # 7) to obtain a higher sorption power iodine sorbent.

Resistant to hydrothermal treatment, iodine sorbents are obtained only according to the proposed process (Table 2). During ten hydrothermal treatment cycles, 94% of the potassium iodide present in the iodine sorbent is removed from the prototype, while only a small fraction of unbound polymeric iodine acceptor is leached from the impregnated samples in the same process.

The determination of the hydrothermal resistance of iodine sorbents is carried out by adding 20 g of sorbent prepared according to Examples 1-4 to 100 g of 90-95 ° C distilled water and holding for 10 minutes. After trapping water, the operation is repeated up to 10 times.

The invention is illustrated by the following examples:

example

Prepare lOOOg 1% PDMDAAJ by dissolving 990 mL of water in 10O PDMDAAJ. Add 500g of granular activated carbon (TU 6-162727-84) to the prepared solution. After 20 min, remove the solution. Weight of wet pellets 100%. They are spread in a thin layer and dried in a convection dryer at 90 - 105 ° C. An iodine sorbent containing 1% PDMDAAJ is obtained. Under static conditions, it binds 22mg L · / lg of sorbent from air (Table 1, No 3). After 10 cycles of hydrothermal treatment, 0.75% PDMDAAJ remains on the sorbent mass (Table 2).

example

The impregnation is carried out according to Example 1, but uses only 2% PDMDAAJ solution instead of 1% PDMDAAJ solution. Obtained 2% iodine sorbent

PDADMAJ. Under static conditions in air it binds 33 mg I ₂ / lg resin, dynamic - 90mg ₂ / lg resin (Table 1, No. 4).

example

The impregnation is performed according to Example 1, only 4% PDMDAAJ solution is used instead of 1% PDMDAAJ solution. Incoming? iodine sorbent containing 4% PDADMAJ. Under static conditions, it binds 41mg I ₂ / lg of sorbent from air (Table 1, No. 5). After 10 cycles of hydrothermal treatment, 2.94% PDMDAAJ remains on the sorbent mass (Table 2).

Example 10000g of 1% PDMDAAJ solution is prepared according to Example 1. Immerse 150 g of activated carbon in the prepared solution. After 20 min, remove the solution. Weight of wet fibrous coal 500%. The wet fibrous charcoal is dried in a convection dryer at 90 to 105 ° C. An iodine sorbent containing 5% PDMDAAJ is obtained. Under static conditions in air, and bound 154mg ₂ / lg resin, dynamic - 450 mg I ₂ / lg resin (Table 1, No. 4).

example

Prepare lOOOg 1% potassium iodide solution by dissolving lOg KI (GOST 4232-74) in 990 mL water. 500g of granulated activated carbon is added to it. After 20 min, the solution is suctioned off. Weight of wet pellets 100%. They are spread in a thin layer and dried in a convection dryer at 90 - 105 ° C. Obtained iodine sorbent with 1% CI. Under static conditions, it binds 21mg I ₂ / lg of sorbent from air (Table 1, No 2). After 10 cycles of hydrothermal treatment, 0.06% by weight of potassium iodide remains on the sorbent (Table 2).

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Claims (3)

Definition of the Invention 1. An iodine sorbent consisting of activated carbon and an iodine acceptor, wherein the iodine acceptor is polydimethyldiallylammonium iodide. 2. The iodine sorbent of claim 1, wherein the activated carbon is in the form of granules or fibrous material. 3. A process for preparing an iodine sorbent comprising impregnating the activated carbon with an iodine acceptor solution and drying the resulting product, wherein the activated carbon is impregnated with an aqueous solution of 1-4% polydimethyldiallyl ammonium iodide.