Patent Application
20220186154
The present invention relates to a composition for the removal of chemical residues, to a method for employing said composition, and also to the use of said composition for removing residues on materials, machines, and equipment soiled with chemicals of any type.
In industry there is thus far no effective solution for decontaminating materials, machines, and/or equipment soiled with chemical contaminants. In the event of a chemical accident during a maintenance operation or during manipulations, splashing with liquids, solids or gases can occur, thus resulting in contamination of the work area and/or of protective equipment. Materials and surfaces in the work area are then soiled by the chemical without this necessarily being visible, thus giving rise not only to risks of chemical injury for workers (skin contact with the chemical or inhalation) but also to risks of corrosion for materials and consequent shortening of the service life thereof.
The use of an absorbent mineral such as diatomaceous earth or sepiolite or of a specialty absorbent such as TRIVOREX® or UNISAFE PH PLUS® makes it possible to neutralize splashes on floors. However, when the contaminated surface is not horizontal but is vertical or uneven (walls, ceilings, machines and protective equipment), it is not possible to use these absorbents.
None of the existing solutions available to those skilled in the art are able to effectively decontaminate said surfaces.
Those skilled in the art can either:
When fluoride-based compounds (such as hydrofluoric acid) are spilled or splashed in areas that are difficult to reach, those skilled in the art are faced with an even greater problem. This is because, in addition to eliminating the hazard associated with the corrosiveness of the chemical, it is also necessary to protect against its toxicity. Fluoride poisoning can occur after skin exposure, exposure via the gastrointestinal tract and/or exposure by inhalation. It results in bone, respiratory, and heart disorders that can lead to death. The potentially lethal dose amounts to 5 mg/kg body weight.
None of these solutions mentioned above makes it possible to reduce toxicity from fluoride ions.
A chemical decontaminant for the specific material hydrofluoric acid and derivatives is LeVert HF. The latter makes it possible to decontaminate the surface of soiled materials by restoring the pH of the contaminating chemical to between 5.5 and 9 and by binding fluoride ions. Decontamination is considered to have been effective when the threshold of 1.5 mg/L at which the concentration of fluoride ions becomes non-hazardous has been reached in the decontaminant-fluorochemical mixture. Those skilled in the art must use an external means (test strips for measuring fluoride ions, ion meter) to check that this limit of 1.5 mg of fluoride ions per liter of waste has been achieved. However, the action of the chemical decontaminant LeVert HF is limited to hydrofluoric acid and to other chemical compounds containing fluoride ions and therefore does not permit the effective neutralization of basic chemicals. Such compositions therefore not of universal utility and are unable to indicate when the decontamination operation is complete. Furthermore, such compositions have a high concentration of the salt NaCl, which corrodes metals.
There is accordingly thus far no composition that:
(1) makes it possible to decontaminate and neutralize chemicals of any type, and including hydrofluoric acid and derivatives thereof through the binding of free fluoride ions,
(2) does not necessitate an external means of indicating when the acidic/basic decontamination operation is complete,
(3) is not hazardous for humans or for the environment (nontoxic, noncorrosive, nonflammable and nonirritant), and
(4) is free of salts that could cause metals to corrode.
Nevertheless, the present inventors have had the distinction of finding a decontamination composition that presents an excellent compromise between these different criteria (1) to (4).
The invention thus relates to a decontamination composition comprising:
(pKa1+pKa2)/2>5
7>pKa1>4
11>pKa2>7
and an agent having at least one pKa of between 7 and 11, and mixtures thereof,
It also relates to a decontamination method employing the composition of the present invention, characterized in that it comprises the following steps:
(1) dispersing the composition on a surface soiled with a chemical,
(2) repeating step (1) until a pH of between 5.5 and 9 is obtained, and
(3) optionally rinsing with water to prevent colored crystals from appearing during drying of the decontaminated surface.
It also relates to the use of the composition according to the present invention for decontaminating materials, machines, and equipment soiled with chemicals of any type.
The invention relates to a decontamination composition comprising:
(pKa1+pKa2)/2>5
7>pKa1>4
11>pKa2>7
and an agent having at least one pKa of between 7 and 11, and mixtures thereof,
“Salts HaXb” is understood as meaning not only salts in molecular form but also particles composed of salts HaXb agglomerated together and not dissolved in solution.
Said primary neutralizing agent may be the complex AlNa2EDTAOH.
Said primary neutralizing agent may be present in an amount ranging from 0.1% to 25% by weight, preferably from 10% to 20% by weight, and more preferably from 15% to 18% by weight, relative to the total weight of the composition.
Said secondary neutralizing agent may be selected from ascorbic acid and salts thereof, hydrogen carbonate and salts thereof, creatinine, glutathione, isoguanine, adenine, an amino acid and salts thereof, such as glutamic acid, aspartic acid, arginine, lysine, ornithine, cysteine, and mixtures thereof.
Hydrogen carbonate and salts thereof may be sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, and mixtures thereof.
Glutamic acid and salts thereof may be glutamate in the form of sodium glutamate, sodium L-glutamate hydrate, and mixtures thereof.
Salts of aspartic acid may be aspartate.
Salts of arginine may be L-arginine monohydrochloride.
Salts of ornithine may be L-ornithine monohydrochloride.
Salts of lysine may be L-lysine hydrochloride.
In one particular embodiment, said secondary neutralizing agent is selected from sodium glutamate, lysine, ornithine, cysteine, and L-arginine.
Said secondary neutralizing agent may be present in an amount ranging from 0.1% to 50% by weight, preferably from 1% to 20% by weight, and more preferably from 5% to 15% by weight, relative to the total weight of the composition.
Examples of additives that may be mentioned are dyes, fragrances, viscosity modifiers, and mixtures thereof.
In one particular embodiment, said color indicator or said mixture of color indicators has a color-change zone at a pH of between 1 and 7, preferably between 2 and 6, and more preferably between 2.5 and 5, and a color-change zone at a pH of between 8 and 13, preferably between 8.5 and 11, and more preferably between 9 and 10.
Color indicators that may be mentioned are methyl red, thymol blue, ethyl orange, methyl orange, tropaeolin OO, bromophenol blue, and mixtures thereof.
The color indicator may be present in an amount ranging from 0% to 5% by weight, preferably ranging from 0.001% to 1% by weight, and more preferably from 0.002% to 0.5% by weight, relative to the total weight of the composition.
The composition of the present invention is free of salts HaXb, which means it causes little or no corrosion or degradation of surfaces (plastics, metal, glass, etc.) on which it is applied and of metal surfaces in particular, which corrode easily.
In particular, the composition of the present invention is free of at least one compound selected from the salt NaCl, the salt KCl, the salt NaF, and the salt NaBr.
The composition of the invention advantageously comprises:
(a) from 5 to 25%, preferably from 8 to 20%, and more preferably from 10 to 17%, of a primary neutralizing agent,
(b) from 1 to 50%, preferably from 5 to 15%, and more preferably from 8 to 13%, of a secondary neutralizing agent,
(c) from 0% to 5%, preferably from 0.001% to 1%, and more preferably from 0.002% to 0.5%, of a color indicator or of a mixture of color indicators,
(d) water,
said percentages being percentages by weight relative to the total weight of the composition.
The present invention also relates to a decontamination method employing the composition of the present invention, characterized in that it comprises the following steps:
(1) dispersing the composition on a surface soiled with a chemical,
(2) repeating step (1) until a neutral pH is obtained, preferably until a pH of between 5.5 and 9 is obtained, and
(3) optionally rinsing with water to prevent colored crystals from appearing during drying of the decontaminated surface.
In the case where the composition includes a color indicator, step (1) is repeated until a neutral pH is visually obtained, preferably until a pH of between 5.5 and 9 is obtained.
The present invention also relates to the use of the composition of the present invention or as obtained by the method of the present invention for decontaminating materials, machines, and equipment soiled with chemicals of any type.
“Decontaminate” is understood as meaning not only the mechanical entrainment of the polluting chemical but also the neutralization thereof, that is to say:
The contaminating chemical may be a strong base or a strong acid, preferably sodium hydroxide, hydrochloric acid, hydrofluoric acid or derivatives thereof, such as ammonium fluoride or sodium fluoride, or mixtures thereof.
The state of decontamination may be monitored through the presence of a color indicator or of a mixture of color indicators. An external means of checking the acidic/basic decontamination may therefore not be necessary.
The composition according to the present invention can be used to decontaminate materials, machines, and equipment soiled with hydrofluoric acid and derivatives thereof, such as ammonium fluoride or sodium fluoride.
Without being bound by any one theory, the primary neutralizing agent makes it possible to neutralize fluoride ions.
“Neutralize fluoride ions” is understood as meaning preventing their availability and their deleterious action and therefore arresting their toxicity.
The composition of the invention advantageously makes it possible to restore the concentration of free fluoride ions to an acceptable value, that is to say a value of less than 1.5 mg/L.
This threshold corresponds to the maximum permitted fluoride concentration in water for human consumption (WHO, 2004). An individual may consume (by drinking) 2 L per day of water having a concentration of 1.5 mg/L without developing dental fluorosis. Similarly, an individual with skin exposure to a liquid having a fluoride concentration of 1.5 mg/L will not exhibit deleterious effects.
The fluoride ion concentration can be measured with an ion meter or with an electrode specific for fluoride ions.
An electrode specific for fluoride ions can be an electrode having a membrane permeable only to fluoride ions. An example of a membrane permeable only to fluoride ions includes, but is not limited to, a europium-doped lanthanum fluoride membrane.
The invention will now be illustrated by the non-restricting examples hereinbelow.
In the examples that follow, the following commercial products are used:
A decontamination composition 1 was prepared that comprised:
The decontamination composition 1 is free of salts HaXb as defined according to the present invention.
Neutralization Test
A neutralization test was carried out with the following liquids: 1 M sodium hydroxide (NaOH) and 1 M hydrochloric acid (HCl), using the composition prepared in example 1, according to the following procedure:
to 1 mL of 1 M sodium hydroxide (NaOH) or 1 mL of 1 M hydrochloric acid (HCl) were successively added:
1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 10 mL, 20 mL, 30 mL, 40 mL and/or 50 mL of the solution from example 1, waiting a maximum of 1 minute between each addition, and the pH was measured after each addition.
The results are presented in table 2 and depicted in
Color Test
A color test was carried out with the following liquids: 1 M sodium hydroxide (NaOH) and 1 M hydrochloric acid (HCl), using the composition prepared in example 1, according to the following procedure:
into a beaker containing 20 mL of solution from example 1 are added 10 mL of 1 M sodium hydroxide (NaOH) or of 1 M hydrochloric acid (HCl). The color is observed with the naked eye.
A variation in the color of the solution from example 1 as a function of pH is observed.
The results are presented in table 3 below.
Binding of Fluoride Ions Test
A binding of fluoride ions test was carried out with a 1 M solution of ammonium fluoride (NH4F), using the composition prepared in example 1, according to the following procedure:
to 5 mL of a 1 M solution of ammonium fluoride (NH4F) were successively added 1 mL or 5 mL of the solution from example 1, waiting a maximum of 1 minute between each addition, and the concentration of free fluoride ions was measured continuously.
The fluoride ion concentration is measured with a PHM240 ion meter sold by the company Radiometer and an Orion™ brand electrode specific for fluoride ions sold by the company Thermo Scientific.
The results are depicted in
A decontamination composition 2 was prepared that comprised:
The decontamination composition 2 is free of salts HaXb as defined according to the present invention.
Neutralization Test
A neutralization test was carried out according to the procedure from example 1 using the composition from example 2.
The results are presented in table 5 and depicted in
Color Test
A color test was carried out according to the procedure from example 1 using the composition from example 2.
A variation in the color of the solution from example 2 as a function of pH is observed.
The results are presented in table 6 below.
Binding of Fluoride Ions Test
A binding of fluoride ions test was carried out according to the procedure from example 1 using the composition from example 2.
The results are depicted in
A decontamination composition 3 was prepared that comprised:
The decontamination composition 3 is free of salts HaXb as defined according to the present invention.
Neutralization Test
A neutralization test was carried out according to the procedure from example 1 using the composition from example 3.
The results are presented in table 8 and depicted in
Color Test
A color test was carried out according to the procedure from example 1 using the composition from example 3. A variation in the color of the solution from example 3 as a function of pH is observed. The results are presented in table 9 below.
Color Test
A color test was carried out according to the procedure from example 1 using the composition from example 3.
A variation in the color of the solution from example 3 as a function of pH is observed.
The results are presented in table 9 below.
Binding of Fluoride Ions Test
A binding of fluoride ions test was carried out according to the procedure from example 1 using the composition from example 3.
The results are depicted in
In conclusion, decontamination compositions 1 to 3 neutralize 1 M sodium hydroxide and 1 M hydrochloric acid by restoring the pH to between 5.5 and 9. This variation in pH is accompanied by a change in color.
Decontamination compositions 1 to 3 also make it possible to bind fluoride ions by restoring the concentration of free fluoride ions to an acceptable value, that is to say a value of less than 1.5 mg/L.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1901804 | Feb 2019 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2020/050319 | 2/20/2020 | WO | 00 |
