DK151213B - PROCEDURE FOR GAS-OR OR DISSOLVED IOD BONDING - Google Patents

Description

1 151213

The present invention relates to a method for bonding gaseous or dissolved iodine, especially iodine from gaseous or liquid waste streams, for industrial production of the iodine or on removal thereof from waste streams which pollute the iodine.

Iodine is very widespread in nature, and its industrial production generally presents the problem of concentration from aqueous solutions or gaseous mixtures. The same problem arises in connection with the recovery of iodine for economic reasons from liquid or gaseous waste streams. It is also important to concentrate on the radioactive iodine released by nuclear fuel processing for its recovery or on its release during storage.

Various methods for concentrating iodine are known which are contained in small amounts in aqueous solutions or in gaseous mixtures. Bubbling of gaseous waste streams containing iodine in reactive solutions, such as solutions of ammonia, sodium hydroxide, sodium carbonate, sodium thiosulphate, sodium sulfite or silver nitrate, is a frequently used and effective method, but it presents the disadvantage the iodine is converted to metal iodide, necessitating a further step in the isolation of iodine.

Gaseous or dissolved iodine can be absorbed on porous bodies such as activated carbon, zeolites, alumina, magnesium oxide, silica gel, molecular sieves, and glass powders. The adsorption capacity of these bodies can be very significant when the solutions or gaseous mixtures to be extracted are heavily loaded with iodine, but they are insufficient in cases where these solutions or gaseous mixtures contain very little concentrations of iodine. This adsorption ability can be enhanced by impregnating the porous bodies with a metal or metal salt-responsive iodine. Iodides are then formed and the elution presents difficulties. (See "Nouveau Traité de Chi-mie Minérale" by Paul Pascal, editor Masson, hind XVI, 5 pages 451 to 477).

Gaseous iodine or iodine dissolved in aqueous solutions can be extracted with numerous solvents which are not miscible with water. The most frequently mentioned are tetrachlorocarbon, chloroform, sulfur carbon, benzene, petroleum 09 tributylphosphate. However, these extractions necessitate the handling of substantial quantities of solvents, the treatment of which requires considerable precautions ("Encyclopedia of Chemical Technology", KIRK-OTHMER, second edition, volume 11, page 852).

Gaseous or dissolved iodine can be bonded to anion exchange resins (see "Chemical Abstracts", Vol. 74, No. 8, reference 33067). However, this bonding is only possible if the gaseous mixtures or solutions do not contain anions capable of preferentially binding to the iodine 20 on these resins. Regeneration of these resins converts the bound iodine to metal iodide, necessitating an oxidation to recover the iodine.

The applicant has provided a method which allows the resin to be bonded to elemental, non-bound iodine from gaseous mixtures or aqueous solutions without retention of acids or anions present in these mixtures or solutions to maintain it in elemental state. on the resin and to elute it 3Q either in elemental state or in bonded form in metal salt state.

The bonding of elemental iodine by the method of 151213 3

The invention is selective and can be carried out in the presence of strong acid such as sulfuric acid, nitric acid, hydrochloric acid and hydrogen iodide, in the presence of salts such as sodium sulfate, sodium nitrate, sodium chloride, sodium bromide and potassium iodide.

The other halogens can also be extracted with it having peaks capable of binding iodine, but bromine, chlorine and fluorine react with this resin and partially destroy it.

The method of the invention consists in bonding the iodine to a resin of the type specified in claim 1. This resin does not contain groups of cation or anion character, but it does not contain ether groups with non- (OCH2CH2) nO-15 wherein n has a value from 0 to 100.

These ethoxy groups are linked to hydrogen or to groups from a compound containing a labile hydrogen atom such as monoalcohols, polyols, phenol, substituted phenols and carboxylic acids.

The ethoxy groups may be the only alkoxy groups or they may be attached to other alkoxy groups such as propoxy-xy and butoxy groups.

In the particular case where n = 0, the resin contains a single ether group which also possesses the property of 25 a. To bind iodine.

Ethoxy groups are available in a large number of condensation products which are well known as solvents, as surfactants, as basic materials in the production of polyurethane foam and polyurethane resins, as well as in the manufacture of lubricants and hydraulic fluids, and are described. eg. in the book "Nonionic Surfactants" by MARTIN J. SCHICK (Surfactant Science Series).

In the process of the invention, these condensation products can be adsorbed either in a macro-crosslinked resin without ion-forming groups or on a cation exchange resin containing carboxyl groups, or they can be bound by chemical bonding on the polymer forming the resin backbone.

The ability to adsorb condensation products of alkylene oxides and alcohols, alkyl phenols, and acids on macro-crosslinked resins without ion-forming groups and on cation exchange resins containing carboxylic acid groups is well known. The adsorption of the condensation products 15 occurs by contacting their aqueous solution with the resin of the prior art for the use of ion exchange resins and preferably by passing the aqueous solution through a column containing the resin.

The bonding of condensation products of alkylene oxides and 20 alcohols, alkyl phenols and acids through a chemical bond on the polymer forming the resin backbone is accomplished by reacting their alkali metal alcoholate with a resin containing chloromethyl groups.

Chloromethylated resins are well known and usually serve to prepare amino group-containing anion exchange resins. The adsorption of condensation products on macro-crosslinked resins without ion-forming groups or on cation exchange resins containing carboxyl groups is so much easier to carry out, as their hydrophobic base 30 and their molecular weight are considerable, while the bonding of condensation products by reaction of their alkali metal alcoholate is on chloromethyl ester 12 5 with low molecular weight condensation products due to the easier availability of the reactive groups.

The bonding of iodine to ethoxy group-containing resin by the process of the invention occurs by contacting the resin with the aqueous solution containing dissolved iodine or with the gas mixture containing iodine vapors.

The contact between an aqueous solution containing iodine and the resin containing ethoxy groups is carried out by known techniques for the use of ion exchange resins. The preferred technique is that of passing the aqueous solution through a column containing the resin. It is advantageous to allow the aqueous iodine solution to pass upwards in order to provide a distribution of the resin by its density and thus by its iodine content.

The contact between a gaseous mixture containing iodine and the resin containing ethoxy groups is carried out by known techniques used for adsorption of gases by means of 20 activated charcoal.

The iodine bound to the resins containing ethoxy groups can be displaced by known solvents for: iodine, of which they. most important are: ethanol, benzene, ether, dioxane, glycerine, sulfur carbon, cyclohexane, dodecane, chloroform and carbon tetrachloride. Glycol ethers are especially selected: methyl glycol, ethyl glycol, butyl glycol, methyl diethylene glycol, ethyl diethylene glycol, butyldiethylene glycol, methyl triethylene glycol, ethyl triethylene glycol and butyl triethylene glycol.

30 In the elution with iodine-bound solvent, the ethoxy groups derived from ethylene oxide condensation products adsorbed on macro-crosslinked resins without ion-forming groups or on cation exchange resins with carboxyl groups are part of the iodine * condensation products, thereby reducing the binding ability to iodine for subsequent periods of use. However, this capacity deterioration is small.

The iodine is recovered from the solvent by prior art, such as evaporation or precipitation of insoluble iodide. The solvent may be returned directly to a subsequent elution or it may be distilled prior to return. Distillation of the solvent leaves as evaporation residue the included condensation products. These can be re-bound to the resins so that they regain their original binding ability to iodine.

Elution with iodine-retained solvent has peaks whose ethoxy groups are bound by chemical bonding on the polymer constituting the resin backbone, bringing only iodine and, consequently, no deterioration of the bonding ability to iodine of the resin from a 20 application period for the next one. The iodine is recovered from the solvent by prior art, such as evaporation or precipitation of insoluble iodide, and the solvent is returned.

The process of the present invention, which allows to concentrate iodine which is in a very dilute state in aqueous solutions or in air, can be integrated with various methods of industrial production of iodine. It allows extraction of iodine from contaminated waste streams for recovery of the iodine or for purification of the waste streams.

The resins containing ethoxy groups can bind radioactive iodine, especially the isotopes 129 and 131 of iodine released by nuclear fuel processing. This binding can be carried out under the most demanding conditions which exist in the treatment of irradiated fuel, ie. from solutions of nitric acid diluted with water or from gas mixtures containing nitric oxide vapors.

The following examples further illustrate the invention: EXAMPLES 1 TO 9

These examples illustrate the bonding of iodine to resins containing ethoxy groups derived from ethylene oxide condensation products adsorbed on a macro-crosslinked resin type without ion-forming groups.

To produce the resin, at a rate of 600 ml per hour, two liters of an aqueous solution containing 40 g of ethoxylated nonylphenol with 10 molecules of ethylene oxide are passed through a column filled with 100 ml of macro-crosslinked resin without ion-forming groups (AMBER-15 LITE XAD-4, registered mark of ROHM & HAAS), which allows one liter of water to pass through at the same rate to displace the excess, non-bound ethoxylated nonylphenol.

Analysis of ethoxylated nonylphenol in the solution and in the wash water which has passed the resin shows that 24 g of this product has been bound.

By proceeding in a similar manner, resins whose ethoxy groups are derived from other condensation products are prepared.

An aqueous solution containing 40 g of iodine and 80 g of potassium iodide is then poured at a rate of 400 ml per hour. liters through a column filled with 100 ml of resin containing ethoxy groups and previously prepared by the above method.

A solution containing the total amount of potassium iodide added and a small amount of iodine is collected, allowing calculation of the amount of iodine which has been bound to the resin.

Under these reaction conditions, the following results were obtained: Weight in g of solder in solder (g)% iodine added.

Ethoxy group ethoxylated yeast 40 bound retained pears original product bun / l passed per suffering it at 1 li-. liters of moisture moist resin moist hard resin pix

Nonylphenol ethoxylated with 10 moles 240 6 (X) S 542 90.5

EO

Octylphenol ethoxylated with 30 moles 280 600 g 553 92.2

EO

C13 C15 al alcohol alcohol ethoxylated with 190 600 g 512 85.8

7 mol EO

Nonylphenol ethoxylated 220 400 g 380 95

with 6 moles of EO

Hexanol ethoxylated with 170 400 g 352 88

3 mol EO

Butyl triethylene glycol 190 400 g 277 69.5 col

Ethyl triethylene glycol 180 400 g 270 67.5 col

Methyl diethylene 180 370 g 273 73.8 glycol

Methylglycol 180 400 g 208 67 or 151213 EXAMPLES 10 TO 18

These examples illustrate the bonding of iodine to resins containing ethoxy groups derived from ethylene oxide condensation products adsorbed on a cation exchange resin containing carboxyl groups.

5 liters at a rate of 6θΟ ml per hour 1 liter of an aqueous solution containing 20 g of ethoxylated nonylphenol with 6 molecules of ethylene oxide through a column filled with 100 ml of cation exchange resin with carboxylic acid groups (AMBERLITE IRC 84, trademark of ROHM & HAAS), then 1 liter of water is passed at the same rate to displace ethoxylated nonylphenol which has not been bound to the resin.

Analysis of ethoxylated nonylphenol in the solution and in the wash water that has passed through the resin shows that 13 g of this product has been bound.

An identical process produces resins whose ethoxy groups are derived from other condensation products.

Then, at a rate of 400 ml per hour, an aqueous solution containing 40 g / l iodine and 80 g / l potassium iodide is passed through a column filled with 100 ml of the resin prepared by the technique described above.

A solution containing the total amount of potassium iodide added and a certain amount of iodine is collected which allows calculation of the amount of iodine bound to the resin.

Under these reaction conditions, the following results were obtained: n 151213 Weight in g of solder in solder (g)% iodine added.

Ethoxy group ethoxylated yeast 40 bound retained pears original product bun / l passed per suffering it at 1 li-. liters of moisture to resin moist hard resin pix

Nonylphenol ethoxylated with 10 moles of 130 400 g of 2 65

EO

Octylphenol ethoxylated with 30 moles of 180 400 g of 282 70.5

EO

C-, C-C, c-alko-13 well ethoxylated with 7 mol 180 480 g 350 73

EO

Nonylphenol ethoxylated 130,500 g 3 ^ 0 72.2

with 6 moles of EO

Hexanol Ethoxy · * ·· clay with 3 190 400 g 300 75

mol EO

Butyl triethylene glycol 190 400 g 218 54.5

Ethyltriethylene glycol 190 400 g 146 3 5

Methyldiethylene glycol 190 400 g 14 & 3 ^, 5

Methylglycol 190 400 g 80 20 EXAMPLES 19 TO 22

A resin having ethoxy groups derived from ethylene oxide condensation products bonded by chemical bonding to the polymer constituting the resin backbone is prepared.

In a 500 ml flask equipped with a cooling device, with a temperature gauge, with the addition of nitrogen and with stirring, 0.33 mole of sodium alcoholate of methyl triethylene glycol diluted in 150 g of diethylene glycol dimethyl ether is then added to 50 g of resin formed as a skeleton. of styrene and divinylbenzene copolymer to which are attached 10 chloromethyl groups (0.275 groups per 50 g of resin).

The mixture is heated to 140 ° C for 12 hours, then filtered after cooling the resin and washed with water. 0.24 groups 0Η ^ (00Η20Η2) ^ 0- are bound and the volume in water of the resin thus synthesized is 190 ml.

Another method of preparation for resin containing ethoxy groups derived from ethylene oxide condensation products, which is attached by chemical bonding to the polymer constituting the resin backbone, can be used.

In a 500 ml flask equipped with a cooling device, a 20 temperature gauge, nitrogen inlet and stirring, 0.275 moles of sodium alcoholate of ethoxylated nonylphenol with 6 molecules of ethylene oxide diluted in 170 g of xylene are prepared, then 50 g of a resin is added. represents a sphere of styrene and divenylbenzene copolymer to which are attached chlorine methyl groups (0.275 groups per 50 g of resin).

The mixture is heated to 130 ° C for 8 hours, after which the resin after cooling is filtered off and washed with water. 0.17 groups

CgHig - ^ - (OCH2CH2) g0- has been bound to the resin, whose volume in water is now 260 ml.

131213 13

By one of the methods described above, resins were prepared containing the following groups:

Number of groups Volume of bound per 50 Moist Resin Chloromethics (ml) Clay Resin __ ^ (OCH2CH2) 6 ° - 0.17 260 C13-C15 alkyl- (OCH2CH2)? 0.21 270 C4Hg (OCH2CH2) 30-0.21 270 C8HrrC1V (° CH2CH2 ^ 30 ° 0.10 190 CH2 (OCH2CH2) 30- 0.24 190 CH3 (OCH2CH2) 20- 0.24 190 CH3 OCH2CH20- 0.24 190 CH

At a rate of 100 ml per an hourly solution is passed through an aqueous solution containing 40 g / l iodine and 80 g / l potassium iodide 5 through a column filled with 30 ml of a resin prepared by one of the aforementioned methods in which the ethylene oxide condensation products are bonded to it. polymers constituting the resin backbone through a chemical bond.

10 A solution containing the total amount of potassium iodide added as well as an amount of iodine is obtained which allows the calculation of the amount of iodine bound to the resin.

Under these reaction conditions the following results were obtained: solder in solder (g)% iodine of 40 bonded bound

The species g / 1 of the ethoxy groups passed per · lipr. liters of moisture resin have peak C13-C15 alkyl (00Η20Η2)? 0- 330 g 300 91 c4h9- (OCH₂CH₂) 30-400 g 250 62.5

CgHig - ^^ - (OCH2CH2) 60- 330 g 260 79 C8H1 '/ "Cy * (° CH2CH2 ^ 0 °" 330 δ 300 91 EXAMPLE 23 TO 28

It is allowed to pass at a rate of 200 ml. An hourly aqueous solution containing 250 mg / l iodine and 0.5 g / l potassium iodide through a column filled with 20 ml of a resin prepared by one of the methods described in Examples 19 to 22. The total amount of potassium iodide added and a certain amount of iodine are collected which allow the calculation of the amount of iodine bound by the resin.

Under these reaction conditions, the following results were obtained: 15 solvents in solvents (g)% iodine of 40 "bound bound

The species g / l of the ethoxy groups passed per · lipr. liters of grit resin have a peak Cl3-Cl5-a1ky1- (OCH2CH2) 70-210 g 190 90.5 C4H9 - (OCH2CH2) 30-275 g 220 80 C9HirO2 (OCH2CH2) 6 ° - 280 S 240 86 CH5 - (OCH2CH2) 30-250 g 230 92 CH3- (OCH2CH2) 20-190 g 177 93.2 CH3-0CH2CH20 125 g 76 60.5 EXAMPLES 29 TO 33

You are allowed to pass at a rate of 250 ml per minute. an hourly aqueous solution containing 2.5 g / l iodine and 5 g / l potassium iodide through a column filled with 30 ml of resin prepared by analogy with one of the methods described in Examples 19 to 22. It is collected total amount of potassium iodide added and a certain amount of iodine which allows calculation of the amount of iodine bound to the resin.

Under these reaction conditions, the following results were obtained: 151213 I6 solute in solution (g)% iodine of 40 bound bound

The species g / 1 of the ethoxy groups passed per LipR. liters of grit resin have peaks C9H19 ~ 3 3 O C'H2C'H2 ^ 60- 330 g 240 72.8 C8E17 ~ (^ y ~ (° CH2 CH2) 30 ° - 375 g 240 64 C13 "C15" alkyl " 375 g 270 72 C4Hg- (OCH2CH2) 30-500 g 280 56 CH2 O- 500 g 110 22

The test carried out with resin to which ethoxylated nonylphenol has been added has been repeated, each time eluting the resin with different solvents to test their effectiveness.

In this example, 7 to 7.5 g of iodine have been bound to the resin in each test. Rinsing with 50 ml of solvent on the 30 ml resin allowed elution

Benzene 2.2 g of iodine

Methanol 2.8 g iodine

Sulfur carbon 0.3 g iodine

Chloroform 1.2 g iodine

Cyclohexane 0.7 g iodine

Dodecan 0.9 g iodine

Methylglycol 7.1 g of iodine

Methyl diethylene glycol 7.3 g of iodine

Ethyl diethylene glycol 6.4 g of iodine

Butyl triethylene glycol 7.2 g of iodine

This shows the efficiency of the glycol ethers for eluting iodine bound to the resins and for regenerating them.

EXAMPLE 34

It is allowed to pass at a rate of 200 ml. per hour 37 liters of an aqueous solution containing 1.48 g of iodine 5 (40 mg / l) through a column filled with 20 ml of resin containing the groups Cq H 2 O = (OCH 2 CH 2 A solution containing 0.26 g of iodine is collected. The amount of bound iodine is thus 1.22 g corresponding to 6 i g per liter. liter of resin and 82% of the added iodine-10 amount.

EXAMPLE 35

At a rate of 200 ml. 86 liters of synthetic seawater containing per hour are allowed to pass. l:

NaCl 26.70 g

MgCl2, 6 H2 O 7.00 g

MgSO 4, 7 H2 O 4.30 g

CaSO 4, 2H 2 O 1.75 g KCl 0.72 g to which is added solder 40 mg through a column filled with 20 ml of resin with groups 15 C 1 -C 4 alkyl-COCH 3 H 2 yO- bound to the resin. A solution containing 250 mg of iodine is collected. Thus, the bound amount of iodine is 3.19 g corresponding to 159 g per liter of resin and 92.5% of the added iodine amount.

EXAMPLE 36

At a rate of 200 ml. 108 liters of synthetic sea water of the composition of Example 35 is allowed to pass, to which is added 10 mg of iodine per hour. per liter, through a column filled with 20 ml of resin with the groups C 1 -C 2 -alkyl- (OCE 2 C 2) 7O- bound to the resin.

A solution containing 35 mg of iodine is collected. Thus, the amount of bound iodine is 1055 mg corresponding to 52 g per liter. liter of resin and 97.5% of the iodine amount.

EXAMPLES 37 and 58

At a rate of 200 ml. 28 liters of an aqueous crude solution containing 7 g of iodine (250 mg / l) and 14 g of potassium iodide are passed through a column of 20 ml resin with ethoxy groups derived from polypropylene glycol of molecular weight 1800 which is ethoxylated with 5 molecules of ethylene oxide and adsorbed on a macro-cross-linked resin without ion-forming groups (AMBERLITE XAD

4, the trademark of ROHM & HAAS) prepared according to the method of Examples 1 to 9.

A solution containing 0.6 g of iodine and 14 g of potassium iodide is collected. Thus, the amount of bound iodine is 6.4 g / 20, corresponding to 320 g / ml. liter of resin and 91.5% of the added iodine amount.

Under the reaction conditions of this example, absorbing on the resin prior to the iodine a C ^-C ^ alcohol ethoxylated with 7 molecules of ethylene oxide instead of propylene glycol of molecular weight 1800 ethoxylated with 5 molecules of ethylene oxide was bound per . per liter of resin 366 g of iodine out of 400 g sent through the resin, corresponding to 91 »5% of the added iodine amount.

EXAMPLE 59

At a rate of ΐ6θ ml pe. 10 h of a solution of 2.5 g of iodine (250 mg / l) in 3 N nitric acid is passed through a column filled with 20 ml of resin containing ethoxy groups derived from C , which is ethoxylated with 7 molecules of ethylene oxide and absorbed on a macro-crosslinked resin without ion-forming groups (AMBERLITE XAD 4, trademark of ROHM & HAAS).

A solution of 3 normal nitric acid containing 0.75 g of iodine is collected. The amount of bound iodine is thus 1.75 g corresponding to 87 g per liter. liters of resin and 70% of the iodine added.

EXAMPLE 40

At a rate of 120 ml per 8 hours of a solution of 2.0 g of iodine (250 mg / l) in 3 N 15 nitric acid is allowed to pass through a column filled with 20 ml of resin with the groups CH

A solution of 3 N nitric acid containing 0.65 g of iodine is collected. Thus, the amount of bound iodine is 1.35 g corresponding to 67 g per liter of resin and 67> 5% of the added iodine amount.

EXAMPLES 41 AND 42

Passing air loaded with approx. 1 mg of iodine per day. liter and at a rate of 100 liters per liter. hour through 50 hours through a column filled with 20 ml of resin with the groups (OCH ^ CHg) 300 bonded to the resin.

After the air flow is stopped, the iodine bound to the resin is displaced with 50 ml of methyl glycol. The amount of iodine eluted with methyl glycol is 4.5 g, which corresponds to 225 g of iodine bound per liter. liter of resin and 90% of the added iodine amount.

Using the reaction conditions of this example and with a resin to which are attached the groups C9H19 "" "" (0GH2CH2 ^ 6 ° "" were bonded 190 S per liter of resin.

EXAMPLE 45

Passing air loaded with approx. 0.2 mg 10 iodine per liter, at a rate of 500 liters per · hour for 50 hours through a column filled with 20 ml of resin with the groups C ^ Hg- (oci ^ ci ^) to the resin.

After stopping the flow of air, the iodine bound to the resin is displaced with 50 ml of methyl glycol. The amount of 15 iodine eluted with methyl glycol is 4.3 g, which is equivalent to 215 g of iodine bound per liter. liter of resin and 86% of the added iodine amount.

A subsequent flushing with air loaded with iodine under the same reaction conditions on these 20 ml of resin 20 allows binding of 240 g of iodine per liter. liter of resin.

EXAMPLE 44

Passing air loaded with approx. 25 mg of iodine and approx. 500 mg of nitrogen peroxide per liter, at a rate of 50 liters per liter. hour by hour through a column filled with 50 ml of resin with ethoxy groups derived from ethoxylated nonylphenol with 10 molecules of ethylene oxide adsorbed on a macro-crosslinked resin without ion-forming groups (AMBERLITE XAD 4, trademark of ROHM & HAAS).

151213 21

Then you let air that is loaded with approx. 25 mg of iodine per liter, but without nitrogen peroxide, at the same rate for 7 hours. Despite the presence of the nitrogen peroxide adsorbed on the resin, the iodine of this resin binds.

After interrupting the flow of air, the bound iodine is replaced by 100 ml of methyl glycol. The amount of iodine eluted with methyl glycol is 9.4 g, which is equivalent to 188 g of iodine bound per liter. liter of resin and 94% of the added iodine-10 amount.

Claims (2)

1512131 P_a_t_e_n_t_k_r_a_v_ £ A process for bonding in a gaseous mixture or aqueous solution containing iodine, characterized in that the iodine-containing, gaseous mixture or aqueous solution is passed over a resin containing ether groups of the nonionic nature - (OCH2CH2) nO- wherein n has a value from 0 to 100, which resin is selected from resins obtained by adsorption of an ethoxylated condensation product on a macro-crosslinked resin without ion function, resins obtained by adsorption of an ethoxylated condensation product on a cation exchange resin containing carboxyl groups, and resins obtained by fixing an ethoxylated condensation product, through a chemical bond, on a polymer forming a resin backbone. Process according to claim 1, characterized in that the gaseous mixture or aqueous solution being treated has a radioactive iodine content which is derived from nuclear fuel or vapors or solutions formed by the treatment of nuclear fuel with nitric acid containing liquids. , especially liquid solutions containing nitric acid, nitric oxides and iodine.