RU2110859C1 - Detergent for decontaminating from radioactive and toxic metals - Google Patents

Abstract

FIELD: decontamination of cloth, including linen and overalls. SUBSTANCE: detergent has in its composition surface-active agents, sodium tripolyphosphate, sodium nitrilotrimethylphosphonate, electrolyte, and water. Proportion of components is as follows, mass percent: surface-active agents - 10-15; sodium tripolyphosphate - 40-65; sodium nitrilotrimethylphosphonate - 1-3; electrolyte and water - the rest. Sodium sulfate is primarily used as electrolyte. EFFECT: improved decontaminating efficiency. 2 cl, 2 dwg, 3 tbl

Description

 The invention relates to decontamination and relates to detergents for washing fabric materials, including underwear and clothing, contaminated with radioactive and toxic metals.

 There is an effective method for decontamination of clothes using soda, potassium permanganate, oxalic acid in combination with surfactants, sodium tripolyphosphate (TPF) and synthetic detergents (SMS) in washing, 12 operations in total [1, 2]. This method removes radioactive contamination to the background level. The disadvantage of this method is a significant reduction in the strength of the fabric due to the use of highly aggressive agents, corrosion of equipment, and most importantly, high energy consumption and water consumption and, as a result, huge volumes of low-level wastewater to be treated.

 Also known is a means for removing contaminants from radioactive and toxic metals from various surfaces, including fabric materials, consisting of a base SMS, including 20-30% surfactant, 30-40% TPF, 0.5-3% liquid glass, 0.5 -1.5% carboxymethyl cellulose (CMC), sodium sulfate and water up to 100%, and additionally a mixture of salts of polyaminocarboxylic (PAA) (3-10%) and polyaminophosphonic acids 1-5% [3]. However, studies have shown that this deactivating agent is not effective enough when washing fabric materials contaminated with radioactive metals: for it, the deactivation coefficient (CD), defined as the ratio of the levels of radioactive contamination of samples before and after decontamination, is small even for a mixture of radionuclides containing easily removable cesium 137, and significantly reduced by the fourth cycle of pollution-decontamination. At the same time, among the main requirements for the effectiveness of decontaminating detergents, one of the most important is the absence of the destructive effect of detergent on the surface of the fabric and, as a consequence, the prevention of repeated sorption of radioactive contamination on the surface of the fabric [4]. That is why the stability of CD during the next three cycles of pollution-decontamination is defined as a mandatory indicator of the effectiveness of decontamination [5].

 The invention proposes a new detergent for removing contaminants of radioactive and toxic metals from fabric materials, including underwear and overalls, containing surfactants, TPP, sodium nitrilotrimethylphosphonate (NTF sodium), electrolyte and water in the following ratio, wt.%: Surfactant 10- 15; TPF 40 - 65; TPF 40 - 65; NTF sodium 1 to 3; electrolyte and water up to 100.

 Table 1-3 shows the results of a study of the decontamination efficiency of a series of samples of the proposed new composition (1-7), samples containing all the main components of SMS (8-11), a comparison sample containing only surfactants, TPP, sodium sulfate 13, and the drug "Magnet" (sample 12), produced by industry in accordance with the patent [3] according to TU 9144-001-17734746-93. Samples 1-11 and 13 were prepared by dry mixing. As surfactants used ionic surfactants, which include alkylbenzenesulfonates and alkylsulfonates, and nonionic surfactants, which include polyoxyethylated synthetic alcohols and monoethanolamides of synthetic fatty acids (FFA). As sodium NTF - di- and trisodium salts of nitrilotrimethylphosphonic acid, in particular, commerylate (TU 6-09-20-243-94) and diphonate (TU 6-09-20-235-93) produced in accordance with the patent [6].

Washing solutions were prepared by dissolving samples in water at 50 ± 2 ^° C. The concentration of each sample in the washing solution was 1%.

Decontamination of tissue samples was carried out according to the known method [8]. The treatment regime for contaminated samples with a washing solution is as follows (6 operations):
- treatment with a washing solution at 40-50 ^o With 10 min,
- rinse at 20 ^o With 5 min,
- treatment with a washing solution at 40-50 ^o With 10 min,
- double rinse at 20 ^o C for 5 minutes,
- drying to dry completely.

 Cotton suit fabric — bleached moleskin — was used as workwear materials.

The following solutions were used to contaminate tissue samples:
- a solution of cesium-137 chloride containing 10 ^-3 mol / l potassium chloride, with a volumetric activity (2.0 ± 0.2) • 10 ⁷ Bq / l, the pH of the solution is 5.5-6.0,
- a solution of cerium-144 chloride + praseodymium-144 containing 10 ^-3 mol / l potassium chloride with a volumetric activity (2.0 ± 0.5) • 10 ⁷ Bq / l, the pH of the solution is 5.5-6.0.

Solutions of radioactive substances were applied to the center of tissue material samples in an amount of 0.15 ml. The samples were dried at 22 ± 2 ^o C from 18 to 20 hours

 The contamination-decontamination cycle was repeated 4 times.

 The initial and residual contamination of the samples was measured on a radiometric setup, as described in [5].

 Based on the measurement results, the coefficient of CD deactivation was calculated, which is equal to the ratio of the levels of radioactive contamination before and after decontamination.

 The data obtained are given in table. 1-3.

 As the table shows. 1, the new proposed detergent (samples 1-4) is distinguished by a high deactivating ability (cleaning occurs to the background level) in relation to contaminants with a mixture of radionuclides cesium-137 and cerium-144: due to the inability to give a large load on the device, only the lower boundary KD> 300. This value far exceeds the KD of the Magnit preparation given in the patent [3] and the KD of the comparison sample (13), as well as the KD of those artificial mixtures (samples 10 and 11) that contained the usual SMS base, including liquid glass and CMC.

Further comparison of the effectiveness of decontamination was carried out on the basis of a comparison of CD in relation to pollution with a standard solution of radionuclides ¹⁴⁴ Ce + ¹⁴⁴ Pr.

 As the table shows. 1 (samples 1-7) and FIG. 1, the addition of sodium NTF in an amount of 0.5-3% to the comparison sample 13 increases the deactivation coefficient from 25.3 to 42.0, but there is no further increase in CD with an increase in the content of sodium NTF.

 An essential role in increasing the effectiveness of decontamination is played by an increase in the content of TPF (Table 1, samples 1-5 and Fig. 2). However, increasing the TPF content above 65% is impractical for economic reasons. When the TPF content is below 40%, the CD quickly drops, which determines the lower limit of the TPF content in the proposed detergent.

 An important component of any decontaminating detergent is surfactant. In the table. 2 shows the results of a study of various types of surfactants on the deactivating ability of the proposed detergent containing sodium NTF and an increased amount of TPF. As an example of alkylbenzenesulfonates, sulfonol was used, alkylsulfonates — volgonate, polyoxyethylated synthetic alcohols — syntanol, polyoxyethylated monoethanolamides FFA — syntamide.

 From the table. Figure 2 shows that in the presence of sodium NTF, compositions containing various surfactants in an amount of 5 - 20% give deactivation coefficients that are close in magnitude (examples III and VIII), and are significantly higher than the compositions taken for comparison without sodium NTF (examples I and II). At the same time, it is possible to reduce the total consumption of surfactants from 20 - 25% (examples I and II) to 10-15% (examples IV and VIII) while maintaining a high coefficient of decontamination. The increase in the content of surfactants in the proposed detergent above 15% is impractical, since it does not increase the deactivating ability (examples III and IV). When the surfactant content is below 10%, the washing ability of the agent decreases, which is undesirable.

 The addition to the proposed tool of such components of the standard SMS base as liquid glass and CMC significantly reduces the deactivating ability (Table 1, samples 8-11). Even for sample 8 containing liquid glass, the relatively high CD after 1 cycle of contamination – deactivation (29.5) falls to the fourth cycle to 11.9 (see Table 3).

 The increase in the compositions containing liquid glass and CMC, the content of TPP to 60-65% (table. 1, samples 9, 10) does not lead to an increase in efficiency.

 Sodium sulfate was used as the electrolyte in the proposed detergent, however, this does not exclude the possibility of using other neutral salts commonly used in SMS as an electrolyte.

 To determine the effect of the detergent composition on its deactivating ability with respect to repeatedly polluted tissues, the deactivation coefficients of several samples from the number presented in Table 1 were determined. 1 after each of four consecutive contamination-decontamination cycles.

 As can be seen from the table. 3, the CD of the proposed detergent (samples 1, 3, 4, 6) show stability in the last three cycles and a sufficiently high CD after the fourth cycle (CD> 20). At the same time, the CD of the reference sample and the Magnesium preparation rapidly decrease in the next three cycles and after the fourth one they show unacceptable values: the CD for sample 13 of comparison 12.8, the CD for Magnet (12) 8.5.

Checking the deactivating ability of the proposed detergent at various temperatures showed that the decontamination factors at 80-90 ^{o are} slightly higher than at the temperature of the main study (40-50 ^o ), which allows the use of this detergent at different temperature conditions of washing.

 In accordance with the generally accepted methodology for determining the washing ability, it is shown that such for the proposed detergent (samples 1-4.6) is 100%.

Thus, the new detergent in terms of decontamination efficiency is significantly superior to the Magnet sample; gives stable high results on decontamination during four cycles of contamination - decontamination, can be used at various temperature conditions of washing from 40 to 90 ^o C, has a washing ability of 100%. The indicated properties of the proposed detergent make it possible to significantly reduce energy consumption and water consumption, as well as the volume of wastewater to be cleaned when used to remove contaminants of radioactive and toxic metals from clothes and overalls.

Sources of information
1. Sanitary rules for industrial and urban special laundries for the decontamination of clothing and other personal protective equipment, N 5163-89. - M.: Ministry of Health, 1969, p. 40-41.

 2. Zimon A.D., Pikalov V.K. Deactivation. - M., 1994, p. 296-298.

 3. RF patent N 2035074, cl. G 21 F 9/34, 1993.

 4. Gorodinsky S.M., Goldstein D.S. Decontamination of polymeric materials. - M.: Energoizdat, 1981, p. 31.

 5. GOST 27708-88. Materials and coatings polymer protective deactivable. Method for determining deactivability. - M.: Goskomstandart, 1988, p. 6.

 6. RF patent N 2056428, cl. C 07 F 9/38, 1993.

Claims (1)

1. Detergent for removing contaminants of radioactive and toxic metals from fabric materials, including underwear and clothing, characterized in that it contains surface-active substances (surfactants), sodium tripolyphosphate (TPF), sodium nitrilotrimethylphosphanate (sodium NTF), electrolyte and water in the following ratio of components, wt.%:
SAW - 10 - 15
TPF - 40 - 65
NTF sodium - 1 - 3
Electrolyte and water - Up to 100
2. The tool according to claim 1, characterized in that sodium sulfate is used as the electrolyte.

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