WO2016008802A1

WO2016008802A1 - Device for sampling and analysing chlorinated pollutants

Info

Publication number: WO2016008802A1
Application number: PCT/EP2015/065724
Authority: WO
Inventors: Fabien GERARDIN; Isabelle SUBRA; Vincent JEANDIDIER; Lionel CHENAL; Thierry HENRIET; Stéphane GILLE
Original assignee: Institut National De Recherche Et De Sécurité Pour La Prévention Des Accidents Du Travail Et Des Maladies Professionnelles (Inrs)
Priority date: 2014-07-15
Filing date: 2015-07-09
Publication date: 2016-01-21
Also published as: FR3023915B1; FR3023915A1

Abstract

The invention relates to a device (1) for sampling and analysing chlorinated pollutants, especially nitrogen trichloride and/or chloroform. Said device comprises a base (12) to which a housing (7) is attached, said housing (7) comprising at least one sampling support (5), a spacer (3), a ring (4), a ring (2) for holding said support associated with a filtration membrane (6), at least one lighting means (13), and an electronic circuit for controlling the power of the radiation supplied by said lighting means (13).

Description

DEVICE FOR SAMPLING AND ANALYZING

CHLORINE POLLUTANTS S

The present invention relates to a device for sampling and analyzing chlorinated pollutants, in particular nitrogen trichloride (trichloramine, NC1 ₃ ) and / or chloroform (CHCl3).

Chlorine is widely used because of its low cost, its simplicity of implementation and its bactericidal properties in swimming pools and in the food industry. It is used in various chemical forms such as hypochlorous acid, sodium or calcium hypochlorite, or chlorine gas. Thus, chlorine is currently the disinfectant agent most commonly used in aquatic centers.

Nevertheless, it remains a particularly reactive product in contact with nitrogenous and carbonaceous substances contained in the bathing water. Chlorine in solution, which is mainly in the form of hypochlorite ion or hypochlorous acid, participates in chemical reactions with sweat or saliva generated by human activity or with plant or animal waste.

These reactions lead to the formation of by-products such as halo forms (including trihalomethanes (THMs, including chloroform), haloacetic acids, halo-ketones and chloramines whose most halogenated form, trichloride Nitrogen (trichloramine, NCI3) is very vo lile and irritating to the respiratory tract and to the eyes. Nitrogen trichloride is the cause of chronic bronchitis problems for monitoring staff in water sports centers and food factories. It could also be a triggering factor for asthma, especially in children. Chloroform can also cause ocular and pharyngeal irritation. This should be monitored at various facilities such as food industries and aquatic centers.

Main source of concern for pool staff and occupational hygienists, nitrogen trichloride has been studied toxicological, epidemiological and techno logical. This work led to the proposal of a so - called comfort value, comparable to an average exposure value (VME), equal to 0.5 mg / m ³ in the air, a value from which exposed employees feel discomfort.

The control of air quality, and in particular the concentration of nitrogen trichloride and chloroform, represents a major issue in both economic and health terms. However, to date, there is no tool for measuring the nitrogen trichloride content in halls to ensure a continuous and / or regular monitoring of the exposure of the employee.

A few years ago, only one method of sampling and analyzing nitrogen trichloride was available. Developed in France by the National Research and Safety Institute for the Prevention of Industrial Accidents and Occupational Diseases (INRS), it consists in sampling polluted air in nitrogen trichloride over a period of time ranging from one hour to one hour. eight hours, through a cassette containing filters impregnated with arsenic trioxide. Although accurate, this method nevertheless requires analytical means only available in the laboratory, and therefore unsuitable for field applications.

More recently, the "TRIKLORAME" device, developed by INRS and now manufactured, distributed in kit form by SYCLOPE Electronique and intended for the measurement of nitrogen trichloride in the air of swimming pools and food factories, requires the use of a pump for the extraction of air and the collection of nitrogen trichloride, which is not practical with the activities of the surveillance staff during outpatient sampling.

More recently, another system for sampling and analyzing nitrogen trichloride has been developed as described in document FR 2 969 295. This system does not make it possible to perform a single sampling on a workstation because of the ranges. concentrations that do not correspond to the conditions of exposure of employees to jobs (on average eight hours period). It is therefore not suitable for sampling nitrogen trichloride under the particular conditions mentioned above.

This device proposes the realization of cumulative measurements by successive samplings to estimate the exposure on a workstation (eight hours) under the conditions of concentrations found in a professional environment, in particular in the swimming pools and the agroalimentary factories or any other industry. likely to generate nitrogen trichloride. This solution seems unsatisfactory in comparison with the expectations of users and prevention specialists who require that a sample be taken per workstation over an eight-hour period.

The object of the invention is therefore to solve the problems mentioned above. In particular, an object of the invention is to propose a compact device, autonomous, passive or dynamic (that is to say with the aid of a pump), intended in particular for swimming pool operators, doctors of the and prevention specialists, allowing a simple, fast and inexpensive way to carry out, by continuous monitoring over the entire duration of a workstation, selective sampling of chlorinated pollutants in the air.

Indeed, while the principle of sampling on an autonomous device is known and described in the literature as the applications US Pat. No. 3,985,017 and CA 2,237,133 attest, it is nevertheless true that the system described does not selectively nitrogen trichloride or chloroform under the conditions of exposure of an employee engaged in a professional activity.

The object of the invention is therefore to provide a device for sampling and analyzing chlorinated pollutant (s), preferably nitrogen trichloride and / or chloroform, comprising a base on which a housing is fixed, said housing comprising at least one sampling support, a spacer, a ring, a retaining ring of said support associated with a filtration membrane, one or more means (s) of illumination and an electronic circuit for controlling the power of the radiation provided by said means (s) of illumination. According to one embodiment, the sampling medium is made of quartz fiber and / or cellulosic fiber.

The housing can, for its part, be made of polyvinyl chloride (PVC), or any other polymer not interfering with the sample, and the nylon spacer, or any other polymer not interfering with the sample .

Furthermore, in another embodiment, the filtration membrane may be of a material belonging to a family of fluorocarbon resins, fibers and films, including polytetrafluoroethylene and fluorinated ethylene-propylene.

Preferably, the filtration membrane is Teflon®.

In a preferred manner, the base is a plug base or a convergent base.

Advantageously, the device according to the invention comprises a reflective material at the wavelength of illumination.

According to one embodiment, the device according to the invention comprises two sampling stages, one comprising a first sampling medium impregnated with titanium dioxide, and the other comprising a second sampling medium impregnated with titanium dioxide.

The present invention also relates to a method for sampling and analyzing chlorinated pollutant (s) comprising the following steps:

(a) a device as defined above is exposed to an atmosphere comprising the chlorinated pollutant (s);

(b) the chlorinated pollutant (s) are adsorbed on the surface of the sampling medium impregnated with one or more reagents;

(c) the chlorinated pollutant (s) react with the reagent (s);

(d) the concentration of the product (s) is evaluated. Advantageously, the reaction between the chlorinated pollutant (s) with the reagent (s) is a photocatalysis.

Preferably, the reagent B is titanium dioxide (TiO ₂ ). Alternatively, the reagent B is preferably sodium carbonate (NaC0 ₃ ) and / or sodium hydroxide (NaOH).

Advantageously, the concentration of said chlorinated pollutant (s) is (are) quantifiable by conductimetry or by the analysis of the hypochlorous acid formed during the reaction.

The invention finally relates to the use of a device as defined above in swimming pools and food factories or any other industry likely to generate chlorinated po lluants.

Other objects, features and advantages of the present invention will emerge even more clearly on reading the following description, given solely by way of nonlimiting example, and with reference to the appended drawings in which:

- Figure 1a is a sectional view and perspective of an embodiment of a sampling device according to the invention;

Figure 1b shows another sectional view of the device of Figure 1a;

Figure 1 is a detail view on a larger scale of the device of Figure 1b;

FIG. 1d is an exploded view of the device of FIG.

FIGS. 1e and 1f are profile and top views, respectively, of the device of FIG. 1a;

FIGS. 2a and 2b are sectional and perspective views of two embodiments of a sampling device according to the invention;

- Figure 3 describes the principle of sampling by diffusion, adsorption and reaction;

- Figure 4a is a sectional view in perspective of a sampling medium and a lighting means forming part of an embodiment of a device according to the invention;

- Figure 4b describes the principle of positioning of the lighting means shown in Figure 4a for total illumination of the sampling medium shown in Figure 4a; - Figure 5 describes the principle of positioning three lighting means for a total illumination of a sampling medium;

FIG. 6 is a schematic view of an embodiment of a device according to the invention;

- Figure 7 is another schematic view of an embodiment of a device according to the invention;

FIG. 8 is a schematic view of an electronic circuit;

FIG. 9 shows an example of the positioning of an embodiment of a sampling device according to the invention on a user;

FIG. 10 shows nitrogen trichloride concentration measurements according to a reference method and according to one embodiment of a device according to the invention.

It is further specified that the terms "between ... and ..." and "from ... to ..." used in this specification should be understood to include each of the mentioned terminals.

The device according to the invention is intended for the analysis of chlorinated pollutants, and in particular of nitrogen trichloride and / or chloroform. It can perform ambulatory sampling by being worn by an employee or at a fixed position (if it is a dynamic sample). In addition, the device according to the invention makes it possible to analyze the concentration in the air of chlorinated pollutants, and in particular of nitrogen trichloride and / or chloroform, from the samples taken.

Referring to Figures 1 to 10 which illustrate an embodiment of a sampling device according to the invention.

FIGS. 1a to 1f show a sampling and analysis device 1 for nitrogen trichloride and / or chloroform, which is here in the form of a cylindrical casing 7, fixed to a plug base 12, into which is inserted a sampling support 5 between a spacer 3, located in the upper part of the casing 7, and a ring 4. A second sampling support 14 is inserted below the spacer 3. A light-emitting diode 13 rests in the bottom of the housing 7. A filtration membrane 6 rests on the ring 4 and the assembly is held by a retaining ring 2. The device 1 also comprises an electronic circuit (no shown) to control the power of the radiation provided by the diode 1 3.

The spacer here has a cylindrical shape complementary to that of the housing 7. The ring 4 has, for its part, a cylindrical shape.

It can be seen in FIGS. 1a that the retaining ring 2 is screwed onto the end edge of the casing 7. The screwing means comprise a thread 8 on the retaining ring 2 and a complementary thread 9 on the casing 7. The thread 8 is formed on the inner face of the annular wall of the retaining ring 2, the inner face being intended to face the outer wall of the revolving face of the casing 7. The complementary thread 9 is formed on the outer wall of the revolution face of the housing 7, in the vicinity of the end edge of the housing 7.

It will also be noted that the ring 2 internally delimits a passage making the filtration membrane 6 accessible. It is, however, provided with a peripheral zone 10 by which it rests on the housing and with an internal annular flange 11 projecting axially. in support of snapping against the ring 4 to hold the sampling support 5 between the spacer 3 and the ring 4.

Moreover, the second sampling support 14 is supported under the spacer 3.

According to a preferred embodiment, the cylindrical housing 7 is made of PVC. The sampling support 5 is in turn made of quartz fiber and / or cellulose fiber, the nylon spacer 3, while the filtration membrane 6 is Teflon®.

It will be noted, however, that it is not beyond the scope of the invention when other materials are used for producing the housing 7, the sampling support 5, the spacer 3 or the filtration membrane. 6. The filtration membrane 6 makes it possible to prevent any contamination of the sampling medium by liquid aerosols. It remains permeable to the molecules of nitrogen trichloride and chloroform. A selective sample of nitrogen trichloride can thus be carried out.

FIG. 2a denotes the device for sampling and analyzing the nitrogen trichloride in the passive mode. Indeed, in the case of passive sampling, the lower part of the device 1 is terminated by a plug base 12.

FIG. 2b denotes the sampling and analysis device 1 for nitrogen trichloride and / or chloroform in dynamic mode. Indeed, in the case of dynamic sampling, the lower part of the device 1 is terminated by a convergent shaped base 12 comprising a suction nozzle which is connected to a pump for sampling air flows of 0.5. L / min to l L / min. The housing 7 comprises several bores 17 at the periphery of its lower part, as can be seen in FIG. 1f, on the side of the base in order to allow the sampling of sufficient airflows with the pump, when the sampling is dynamic. .

Thus, the passive collection makes it possible to use the device 1 worn by the employee, and the dynamic picking makes it possible to use the device 1 worn by the employee or at a fixed position.

In passive mode, the operation of the nitrogen trichloride sampling device and / or the chloro form which has just been described is based on the principle of the molecular diffusion of the pollutant from the gaseous medium to a sampling medium previously impregnated with reagents. , as shown in figure 3. In dynamic mode, the pollutant is collected on the sampling medium by forced convection using a pump.

According to this principle of molecular diffusion, with reference to FIG. 3, a compound A, whose ambient concentration is to be determined, passes through a diffusion zone. Compound A is subsequently adsorbed on the surface of the sampling medium impregnated with a reagent B. Compound A then reacts with reagent B to give a product C whose surface concentration can be evaluated.

The pollutant flow density that diffuses through the diffusion zone of the sampling device is governed by the first law of Fick:

j = - D, (1)

ox

with j, the pollutant flux density (mo l / m ² / s), Di, the molecular diffusion coefficient of the pollutant (m ² / s), C, the po lluent concentration (mo l / m ³ ) and x, the diffusion distance (m).

Thus, in order to proceed to the sampling and analysis of nitrogen trichloride and / or chloro form by molecular diffusion, the device 1 is exposed to an atmosphere comprising nitrogen trichloride and / or chloro form. In the present case, the nitrogen trichloride and / or the chloroform is adsorbed on the surface of the support 5 impregnated with one or more reagent (s), and reacts with the reagent (s). The surface concentration of the product (s) resulting therefrom can be evaluated.

The diffusion is then followed by adsorption and by a process using photocatalysis on the surface of the titanium dioxide (TiO ₂ ) impregnated sampling medium acting as a photocatalyst. The support is illuminated by a light source by one or more means of illumination.

When nitrogen trichloride is adsorbed on the sample carrier, it reacts very rapidly and decomposes to form hypochlorous acid and chlorides. At the end of the sampling period, the products thus formed are desorbed from the sampling medium using ultra pure water.

Quantification of the concentration of nitrogen trichloride and / or chloroform is then carried out by conductimetry. For this, the electrodes, supplied with voltage, of the conductivity meter are immersed in the desorbed electrolyte solution. The electrical conductivity value of the solution obtained with the conductivity meter then makes it possible to go back to the concentration of the chemical compounds of the solution by means of abacus or previously known calibration curves. For nitrogen trichloride, another method of quantification may be employed. This is a colorimetric method, based on the specific analysis of the hypochlorous acid formed during the reaction, comparable to the methods of analysis of free chlorine in swimming pool water.

The lighting means may be any technical device for emitting radiation in the UV-A range with a wavelength between 300 and 388 nm. In particular, the lighting means may comprise light emitting diodes (LED DIP) or light emitting diodes surface mounted (LED SMD).

It is then necessary that the entire titanium dioxide-impregnated sampling medium is illuminated with sufficient power by the illumination means for the photocatalytic degradation to take place.

The inner wall of the lower part of the device according to the invention may be covered with a reflective material at the illumination wavelength in order to increase the irradiation incident on the sampling medium.

Several solutions are possible in order to respect these conditions.

The correct positioning of the light-emitting diodes and their technical characteristics are linked to allow sufficient and total illumination of the sampling medium. In addition, to ensure optimal illumination over a minimum period of one workstation, ie 8 hours, the light-emitting diodes must be powered by a battery with sufficient capacity. In addition, in order to ensure constant illumination over time, current regulation is necessary.

In order for the sampling medium to be totally illuminated by means of a single light emitting diode positioned in the axis of the support at a certain distance d, as indicated in FIGS. 4a and 4b, the relation (6) must be respected: x = 2d tan

in which x denotes the diameter of the sampling medium (m);

d denotes the distance between the light emitting diode as shown in Figures 4a and 4b and the sampling medium (m);

a is the opening angle of the light - emitting diode (°).

In addition, the surface of the illuminated sample holder is represented by the relation (7)

where S denotes the area of the illuminated sample holder (m ² ).

Thus, it is deduced that the angle a is represented by the relation

Thus, when a light emitting diode called SMD LED is used, for a surface S of 9.3 cm ² and a distance d of 15 mm, an opening angle of 98 ° is obtained.

When a light emitting diode called LED DIP is used, for a surface S of 9.3 cm ² and a distance d of 12 mm, an opening angle of 110 ° is obtained.

Another solution is to illuminate with the aid of several light emitting diodes judiciously positioned so that the entire sampling medium is totally exposed to UV radiation. Thus, by illuminating with three light-emitting diodes, the positioning of the diodes must comply with certain conditions.

FIG. 5 indicates the positions of the light-emitting diodes to be observed in order to obtain a total illumination of the sampling medium. Circle 1 represents the support of sample to be illuminated by three light-emitting diodes emitting radiation in the UV-A range. This circle should be considered as the circle circumscribed by the equilateral triangle ABC. In order to fully illuminate the sampling medium, it is necessary that each diode is positioned in the middle of each side of the triangle ABC. Circles 2, 3 and 4 represent the areas illuminated by the diodes at the sampling medium for which the illumination is half of the maximum illumination provided by each diode. For a total illumination of the sampling medium, it is necessary that the diameter of these illuminated zones is at least equal to the length of the sides of the equilateral triangle. The diameter x of these zones is thus represented by the relation (9):

(m).

Thus, the relation (10) is given by:

The embodiment using a single diode is preferred.

The power densities of the UV radiation necessary for the photocatalytic degradation of nitrogen trichloride and chloroform are different. It is between 0.5 W / m ² and 1 W / m ² for nitrogen trichloride and between 25 W / m ² and 30 W / m ² for chloroform.

In order to achieve a selective gas sampling, two embodiments are possible.

According to the first embodiment, the two gaseous species are degraded by the method implementing photocatalysis indiscriminately. For this purpose, the titanium dioxide-impregnated sampling medium is illuminated with a light-emitting diode whose power density over the entire support is greater than the maximum power required, ie 30 W / m ² .

According to the second embodiment, it is possible to selectively degrade either the nitrogen trichloride or the chloroform by controlling the light power density provided by the lighting means 13.

Thus, a selective degradation of chlorinated pollutants is operated by controlling the density of light power provided by the means (s) of illumination.

Two solutions are possible to achieve this objective.

The first solution is to configure the device according to the invention as shown in Figure 6. The device then has two sampling stages. It comprises a diode 13, a Teflon® filtration membrane 6, a first titanium dioxide-impregnated pickup 5 for trapping nitrogen trichloride and a second pickup 14, located below the first support 5, impregnated with titanium dioxide for trapping chloroform.

The principle of the device as it is configured consists of superimposing two sampling media impregnated with titanium dioxide. A light emitting diode having a wavelength of less than 388 nm is placed in the lower part of the housing. Its delivered power makes it possible to expose the first membrane to an irradiation of 30 W / m ² . The adsorption and the photocatalytic degradation of the chloroform will be carried out on the support 14. The amount of titanium dioxide deposited on the support 14 allows a transmission of the incident light flux towards the support 5 of about 5%. The irradiation of the support 5 is thus sufficient to allow the degradation of the nitrogen trichloride previously adsorbed on this support 5.

The second solution is based on the use of a single sampling medium impregnated with titanium dioxide as described in FIG. 7.

FIG. 7 shows that the device used comprises a diode 13, a filtration membrane 6 made of Teflon®, and a support of titanium dioxide impregnated sample 5 for entrapment and degradation of nitrogen trichloride alone. The power density received by the sampling medium 5 is then between 0.5 and 1 W / m ² .

For these two solutions, the power density supplied is regulated by an electronic circuit for controlling the power of the radiation of one or more light-emitting diodes.

A switch then makes it possible to control three positions: a position where the electrical circuit is open (the diode or diodes thus emitting no radiation), a position for illuminating the support with a power density greater than 30 W / m ² thus enabling the photocatalytic degradation of chloroform and nitrogen trichloride with the first solution, and a position allowing the support to be illuminated with a power density of between 0.5 and 1 W / m ² , thus allowing degradation nitrogen trichloride with the second solution.

Several control circuits are possible.

A solution is based on the use of a circuit with two resistors in parallel, as described in FIG. 8, the values of which are judiciously chosen so that the light-emitting diode provides the power required for the two described configurations (photocatalytic degradation of the nitrogen trichloride, and photocatalytic degradation of chloroform and nitrogen trichloride).

Thus, as seen in Figure 8, two resistors in parallel are used. The resistor 15 is configured such that the light-emitting diode provides a power density of 30 W / m ² while the resistor 16 is configured such that the light-emitting diode provides a power density of between 0.5 and 1 W / m ² .

In order to make only one measurement of the concentration of chloroform, while remaining based on this principle (with the same control circuit), it is advantageous to replace the filtration membrane 6 with teflon®, intended to prevent the support 5 is not contaminated by liquid aerosols, by a sampling medium 5 impregnated with a reagent.

Indeed, by impregnating the support 5 with a reagent such as sodium carbonate (NaC0 ₃ ) or sodium hydroxide (NaOH), it is then possible to trap nitrogen trichloride on this support. Only chloroform will diffuse on the support impregnated with titanium dioxide. The support will then be illuminated by the light-emitting diode with a power density greater than 30 W / m ² . We can then go from one configuration to another by replacing the Teflon ® membrane with a sampling medium impregnated with reagent and vice versa.

Advantageously, the device which has just been described can be used in swimming pools and agro-food factories or any other industry likely to generate chlorinated pollutants, in particular nitrogen trichloride and / or chloroform. Indeed, the device according to the invention is intended to operate in a pool hall type environment or manufacturing workshop in an agribusiness plant with an air velocity near the device greater than 0.2 m / s.

As Table 1 indicates, the sampling time depends on the concentration of nitrogen trichloride in the measurement space.

Table 1 In order to collect enough nitrogen trichloride on the adsorbent sample medium, the minimum exposure time of the device should be about four and a half hours if the ambient concentration is in the range of 0.2 mg / m ^3. . On the other hand, a little less than two hours of exposure are sufficient to detect a concentration greater than the comfort value set for recall at 0.5 mg / m ³ .

In addition, the device must be placed near the airways of the operator in the case of the wearing of the device by an employee. Figure 9 shows an example of port of the device of the invention by a user.

In one embodiment, the available surface area for the adsorption of nitrogen trichloride molecules is 9.3. 10 ^-4 m ² and the diffusion length is 0.06 m.

Tests conducted in real-life situations were carried out in an aquatic facility with recreational and sporting purposes. They took place over a period of six hours. At the same time, reference samples were taken using dynamic samples taken on a cassette. This method, described in the preamble of the application, is a traditional method developed by the INRS.

Figure 10 shows that six measurements (one sample per workstation) were made using the device of the invention. Concentrations between 0.2 and 0.5 mg / m ³ have been measured, that is, concentrations typically encountered in a professional environment.

In addition, the results indicate a very satisfactory agreement between the dynamic sampling method and those carried out under the actual conditions of exposure of the employees, making the device of the invention ready for use.

Claims

1. Device (1) for sampling and analysis of chlorinated pollutant (s), preferably nitrogen trichloride and / or chloroform, characterized in that it comprises a base (12) on which a housing ( 7) is fixed, said housing (7) comprising at least one sampling support (5), a spacer (3), a ring (4), a retaining ring (2) of said support associated with a filtration membrane (6). ), one or more lighting means (13) and an electronic circuit for controlling the power of the radiation provided by said one or more lighting means (13).

2. Device according to claim 1, characterized in that said sampling medium (5) is made of quartz fiber and / or cellulosic fiber.

3. Device according to one of claims 1 or 2, characterized in that said housing (7) is made of polyvinyl chloride.

4. Device according to one of the preceding claims, characterized in that said spacer (3) is nylon.

5. Device according to one of the preceding claims, characterized in that said filter membrane (6) is a material belonging to a family of fluorocarbon resins, fibers and films, including polytetrafluoroethylene and fluorinated ethylene-propylene.

6. Device according to one of the preceding claims, characterized in that the base (12) is a plug base or a convergent base.

7. Device according to one of the preceding claims, characterized in that it comprises a reflective material at the wavelength of illumination.

8. Device according to one of the preceding claims, characterized in that it comprises two sampling stages, one comprising a first sampling support (5) impregnated with titanium dioxide, and the other comprising a second support of sample (14) impregnated with titanium dioxide.

9. A method for sampling and analyzing chlorinated pollutant (s), characterized in that it comprises the following steps:

(a) a device (1) according to one of claims 1 to 8 is exposed to an atmosphere comprising said chlorinated pollutant (s);

(b) said chlorinated pollutant (s) is adsorbed on the surface of the sample medium (5) impregnated with one or more reagent (s) (B);

(c) said chlorinated pollutant (s) react with said reagent (s) (B);

(d) the concentration of the product (s) (C) is evaluated.

10. The method of claim 9, characterized in that the reaction between said pollutant (s) chlorinated (s) with said reagent (s) (B) is a photocatalysis.

1 1. Method according to one of claims 9 or 10, characterized in that said reagent (B) is titanium dioxide.

12. Method according to one of claims 9 to 1 1, characterized in that the concentration of said chlorinated contaminant (s) is quantifiable by conductimetry or by the analysis of the hypochlorous acid formed during the reaction.

13. Use of a device according to one of claims 1 to 8 in swimming pools and agro-food factories or any other industry likely to generate chlorinated pollutants.