Method for quantifying natural textile fibers and / or chemical textile fibers present in a liquid effluent

Abstract

The present invention relates to a method for quantifying natural fibers and / or chemical fibers present in a liquid effluent from a textile treatment device. A sample of the liquid effluent or its filtration residue is heated in an inert atmosphere between an initial temperature (T0) of at most 290°C and a final temperature (TF) of at least 550°C, and a curve of the evolution as a function of temperature of a representative quantity of hydrocarbon compounds released by the sample is measured. From predefined initial, intermediate (TI) and final integration temperatures of said curve, a quantity of hydrocarbon compounds released by the natural fibers of the sample and / or a quantity of hydrocarbon compounds released by the chemical fibers of the sample is determined.Then, from predetermined correspondence laws, a mass percentage of natural fibers and / or chemical fibers present in the sample is deduced. Figure 2 to be published.

Description

Title of the invention: Method for quantifying natural textile fibers and / or chemical textile fibers present in a liquid effluent Technical field

[0001] The present invention relates to the field of quantification of textile fibers contained in a liquid effluent. In particular, the present invention may relate to the field of quantification of natural fibers and / or chemical fibers contained in a drain liquid from a textile treatment device, such as a washing machine, a laundromat (industrial or not), a laundry, a device for dyeing textiles, or a device for waterproofing textiles.

[0002] Plastic is omnipresent in our daily lives and our clothes are no exception to the rule since approximately 60% of the fibers used in the textile industry worldwide are made from plastic materials such as polyester (PET), polyamide (PA) or acrylic (PAN). Due to abrasion during washing, these synthetic fibers can break into microfibers. It is generally accepted that plastic microfibers are fragments of synthetic fibers whose length is between 1 pm and 5 mm. According to recent studies, more than 700,000 plastic microfibers can be released each time a domestic washing machine is used. Discharged into wastewater, they are only partially retained in wastewater treatment plants (WWTP) and some therefore end up in rivers and then the oceans.It is estimated that 500kT / year of plastic microfibers from washing machines are released into the aquatic environment worldwide, or nearly 33% of the estimated release of primary microplastics.

[0003] In addition to discharges into the aquatic environment, it is important to note that the majority of plastic microfibers retained in wastewater treatment plants end up in sludge during the first stages of treatment. However, the main outlet for this sludge in France, and in most countries, is spreading on agricultural land to improve and fertilize the soil. These microfibers therefore also end up in the natural environment. A post-treatment solution in wastewater treatment plants to reduce the discharge of plastic microfibers into the oceans would only solve part of the problem. In order to be effective, plastic microfiber capture solutions must be deployed as close as possible to the emission sources, i.e. at the outlet of textile washing devices. Furthermore, the scientific community agrees on the need to implement standardized and harmonized methods for the identification and the quantification of plastics in the environment, and in particular of fibers which are the dominant forms in number in the environment. Prior art

[0004] The following documents will be cited during the description:

[0005] Oreillard, M., Barros, CDF, Rouchon, V., Emonnot, C., Lefebvre, V., Moreaud, M., Guillaume, D., Rimbault, F., Pagerey, F. (2022) Quantification and morphological characterization of microfibers emitted from textile washing. Science of the Total Environment 832, 154973.

[0006] Today, there is no reference analytical standard for analyzing plastic microfibers. However, the regulations on these microfibers are being structured to be implemented from 2025 and seek to define performance and thresholds. The work described in the document (Oreillard et al., 2022) has shown the strength of combining advanced microscopy with image analysis methods based on artificial intelligence to quantify fibers contained in wash water and previously deposited on filters. However, a limitation has been raised to this approach: the impossibility of differentiating the nature of the fibers, for example between cotton and synthetic fibers.

[0007] Generally speaking, methods for characterizing plastics and polymers are already known which can be used to identify the presence of plastics and polymers in a sample such as a liquid effluent: for example, differential scanning calorimetry, thermogravimetric analyses, pyrolysis coupled with gas chromatography - mass spectrometry (Py-GC-MS) or Raman spectroscopy. However, these methods are more or less complex and time-consuming.

[0008] For example, the Fourier transform infrared microspectroscopy technique (known by the acronym "pFTIR" for "micro Fourier Transform Interferometer" in English) is known, which makes it possible to identify unknown chemical species by characterizing their composition, size and quantity. However, this method cannot be used for the quantification and differentiation of microfibers whose size is less than approximately 20 μm (detection threshold of the pFTIR method).

[0009] Patent application WO 2022 / 243080 A1 is also known, which relates to a thermal analysis for characterizing the plastic content in samples of a porous medium such as sediments. More specifically, this method is based on measurements of quantities of hydrocarbon compounds (HC), carbon monoxide (CO) and / or carbon dioxide (CO2) released over time by a sample subjected to a heating sequence in an inert atmosphere and then to a heating sequence in an oxidizing atmosphere applied to solid samples. A database of samples previously prepared from different mineral matrices and several types of polymers (PE, PP, PE100, PA6, PAU, PFA and PET), distributed in predetermined concentrations is previously constituted. Parameters from the results of the thermal analysis for the sample to be analyzed are compared with those from the sample database for the identification and distinction of polymer families. However, this method is dedicated to samples comprising both a porous material and at least one polymer (for example, a sample of sand taken from a beach and comprising plastic waste), and does not concern samples of textile fibers. A fortiori, this method does not teach a way to distinguish natural fibers from chemical fibers, and even less a mass quantification of natural fibers and / or chemical fibers.

[0010] The present invention makes it possible to overcome these drawbacks. Summary of the invention

[0011] The present invention relates to a method for quantifying natural fibers and / or chemical fibers present in a liquid effluent from at least one textile treatment device, from a sample of said liquid effluent and / or a sample comprising at least one filtration residue of said liquid effluent. The method according to the invention comprises at least the following steps:

[0012] A) said sample is heated in an inert atmosphere according to a sequence of temperatures having an initial temperature of at most 290°C and a final temperature of at least 550°C, and at least a representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere is continuously measured;

[0013] B) from a curve of the evolution as a function of the temperature of said representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere by said sample, the following are determined:

[0014] - a quantity of hydrocarbon compounds released by said natural fibers of said sample according to a formula of the type: [°°15] ​​QHCN = ' and / °U

[0016] - a quantity of hydrocarbon compounds released by said chemical fibers of said sample according to a formula of the type: [ °° 17] =

[0018] Where TI is an intermediate integration temperature between 390 and 400°C, T0 is an initial integration temperature between said initial temperature of said temperature sequence and said intermediate integration temperature TI of said curve C(T), TF' is a final integration temperature between between said intermediate integration temperature TI and said final temperature of said temperature sequence, said intermediate integration temperature preferably being 390°C, said initial integration temperature JO preferably being between 280°C and 290°C, and said final integration temperature TF preferably being between 550°C and 560°C, and where mech is a mass of said sample;

[0019] C) We deduce:

[0020] - a mass percentage of natural fibers present in said liquid effluent by means of a predetermined correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of said sample, and / or

[0021] - a mass percentage of chemical fibers present in said liquid effluent by means of a predetermined correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of said sample.

[0022] According to an implementation of the invention, from a first plurality of reference samples for which a mass percentage of natural fibers is predetermined, the following steps can be carried out:

[0023] - for each of said reference samples of said first plurality of reference samples, steps A) and B) are applied so as to determine a quantity of hydrocarbon compounds released by said natural fibers for each of said reference samples of said first plurality of reference samples;

[0024] - said correspondence law linking a quantity of compounds is determined hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of a sample by means of a linear regression method applied to said determined quantities of hydrocarbon compounds released by said natural fibers for each of said reference samples of said first plurality of reference samples and to the predetermined mass percentages of natural fibers of said reference samples of said first plurality of reference samples.

[0025] Alternatively, said correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers %FN in said sample can be defined by a formula of the type: %FN = a QHCN

[0026] Where a is between 100 and 250.

[0027] According to an implementation of the invention according to which said natural fibers correspond to cotton and / or linen, said coefficient a can be between 170 and 190, and can preferably be 179.

[0028] According to an implementation of the invention, from a second plurality of reference samples for which a mass percentage of chemical fibers is predetermined, the following steps can be carried out:

[0029] - for each of said reference samples of said second plurality of reference samples, steps A) and B) are applied so as to determine a quantity of hydrocarbon compounds released by said chemical fibers for each of said reference samples of said second plurality of reference samples;

[0030] - said correspondence law linking a quantity of compounds is determined hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of a sample by means of a linear regression method applied to said determined quantities of hydrocarbon compounds released by said chemical fibers for each of said reference samples of said second plurality of reference samples and to said predetermined mass percentages of chemical fibers of said reference samples of said second plurality of reference samples.

[0031] Alternatively, said correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers %FC present in said sample can be defined by a formula of the type: %FC = / )'. QHCC

[0032] Where P is between 200 and 600.

[0033] According to an implementation of the invention according to which said chemical fibers correspond to PET and / or PA, said coefficient P can be between 360 and 390, and can preferably be 372.

[0034] According to one implementation of the invention, said initial integration temperature T0' may be 290°C.

[0035] According to one implementation of the invention, said final integration temperature TF' may be 550°C.

[0036] The invention further relates to a system for implementing the method as described above comprising at least one pyrolysis furnace in an inert atmosphere and means for measuring hydrocarbon compounds.

[0037] Other characteristics and advantages of the method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the appended figures described below. List of figures [Fig IA]

[0038] [Fig. 1A] schematically illustrates the evolution of the temperature as a function of time of the temperature sequence of the first step of the method according to the invention. [Fig IB]

[0039] [Fig. 1B] schematically illustrates the evolution of the temperature as a function of time of a variant of the temperature sequence of the first step of the method according to the invention. [Fig 2]

[0040] [Fig.2] shows examples of curves of the evolution as a function of temperature of the representative quantity of hydrocarbon compounds relative to the mass of the sample released at the end of step 1) of the process according to the invention applied to samples of pure cotton, pure linen, and viscose. [Fig 3]

[0041] [Fig. 3] shows an example of a regression line determined for a plurality of reference samples corresponding to mixtures in various proportions of chemical fibers of different types, the quantity of hydrocarbon compounds released by each reference sample of which was determined by applying steps 1) and 2) of the method according to the invention, and for which the mass percentage of chemical fibers is known. [Fig 4]

[0042] [Fig.4] shows an example of a curve showing the evolution as a function of temperature of the representative quantity of hydrocarbon compounds released during heating of a sample under an inert atmosphere. Description of the embodiments

[0043] The invention relates to a method for quantifying natural fibers and / or chemical fibers present in a liquid effluent from at least one textile treatment device, from a sample of the liquid effluent or from a sample comprising at least one filtration residue of said liquid effluent.

[0044] By "natural fibers" or "natural textile fibers" is meant particles from woven, non-woven, or knitted materials (such as clothing or linen), composed of fibers of natural origin, more precisely of plant origin (for example cotton and linen) or animal origin (for example wool).

[0045] By "chemical fibers" or "chemical textile fibers" is meant particles from woven, non-woven, or knitted materials (such as clothing or linen), composed of synthetic fibers (i.e. derived from hydrocarbon products, such as PET, PA, etc.) and / or artificial fibers (such as viscose) resulting from the chemical transformation (i.e. a transformation changing the nature of the fiber) of a natural material (cellulose, wood, plant, etc.).

[0046] It should be noted that the invention can be applied equally to textile microfibers, that is to say to fibers having diameters generally between 0.1 and 50 microns.

[0047] By "textile treatment device" is meant in particular a textile washing device, for example an individual washing machine (or a washing machine), for domestic or commercial use, a set of washing machines (for example in laundries), an industrial laundries (for example a laundry), etc. But a textile treatment device according to the invention generally comprises any device bringing a textile into contact with a liquid, the liquid then being separated from the textile, such as a device for dyeing a textile, or a device for waterproofing a textile.

[0048] By "liquid effluent from at least one textile treatment device" is meant the liquid from the emptying of the textile treatment device, for example the liquid after washing and / or rinsing and / or spinning in the case of a washing machine. This is subsequently referred to equivalently as "drain liquid". Conventionally, the (micro)fiber load of liquid effluents at the outlet of textile treatment devices is generally limited, with contents between 0.1 and 1000 ppm by weight, generally between 1 and 500 ppm by weight.

[0049] The method according to the invention requires having a sample of the liquid effluent or a sample comprising at least one filtration residue of the liquid effluent. The sample of liquid effluent directly analyzed or the liquid effluent having been filtered to obtain its residue may result from a sample taken at the outlet of the drain pipe of the textile treatment device, for example at each wash in the case of a domestic washing machine, or every hour in an industrial laundry or in a laundry. Such frequencies of sampling of the liquid effluent to be analyzed can make it possible to reliably verify the conformity of the discharges of a textile treatment device with the standards in force.

[0050] According to one implementation of the invention, the method according to the invention may comprise a preliminary step during which it is possible, by means of filtration means, to filter the liquid effluent from the textile treatment device in order to collect a filtration residue from the liquid effluent. It is clear that the filtration means must be capable of collecting at least the natural and / or chemical textile fibers present in the liquid effluent. According to one implementation, the filtration means comprise a membrane filter. Advantageously, the membrane filter may be formed from a material that does not generate particles that could interfere with the quantification of natural and / or chemical fibers according to the invention. Very preferably, membrane filters of the glass fiber type can be used. Indeed, these filters are inert with respect to the method according to the invention (they do not contain or produce natural and / or chemical fibers) and can therefore be introduced, with their residue, directly into a device suitable for implementing the method according to the invention. Advantageously, a known quantity (for example 80%) of a material (for example sand) comprising neither natural fibers nor chemical fibers can be added to the filtration residue thus obtained. This aims to avoid saturating the means for measuring hydrocarbon compounds as described below.

[0051] The method according to the invention can be advantageously but not limitatively implemented by means of the ROCK-EVAL® device (IFP Energies nouvelles, France), as described in patents FR 2227797 (US 3953171) and FR 2472754 (US 4352673). Indeed, the ROCK-EVAL® device comprises at least:

[0052] - a pyrolysis furnace in an inert atmosphere,

[0053] - means for measuring hydrocarbon compounds (HC), for example in the form of a flame ionization detector (FID).

[0054] The method can alternatively be implemented using any furnace allowing heating in an inert atmosphere, cooperating with one or more devices for measuring hydrocarbon compounds.

[0055] The method according to the invention may comprise the following steps:

[0056] 1) Heating sequence under inert atmosphere (pyrolysis)

[0057] 2) Determination of the quantity of hydrocarbon compounds released

[0058] 3) Quantification of natural fibers and / or chemical fibers

[0059] The steps of the method according to the invention are described below in the case.

[0060] 1) Heating sequence under inert atmosphere (pyrolysis)

[0061] During this step, the sample is heated under an inert atmosphere (such as for example under a flow of nitrogen, argon or helium) according to a sequence of temperatures whose initial temperature (denoted T0 hereafter) is at most 290°C, and the final temperature (denoted TF hereafter) is at least 550°C.

[0062] Indeed, the Applicant was able to observe, by means of numerous tests carried out on a plurality of samples of natural fibers of different types (cotton, linen, wool, etc.), that the temperature of 290°C corresponds to the lowest temperature at which organic compounds are released among all natural fibers. For example, linen has a temperature at which organic compounds are released which is higher than that of cotton, which is 290°C2. As will be described below, this initial temperature is also lower than the temperature at which organic compounds are released from chemical fibers.

[0063] Similarly, the Applicant has been able to observe, by means of numerous tests carried out on a plurality of samples of chemical fibers of different types (PET, PA, viscose, etc.), that the temperature of 550°C is sufficient for complete release of the organic compounds from the chemical fibers, whatever their type. As will be described below, this final temperature is also lower than the end temperature of release of the organic compounds from the natural fibers.

[0064] According to one implementation of the invention, the initial temperature T0 may be between 100 and 290°C, and is preferably 200°C. Indeed, the Applicant has been able to observe, by means of numerous tests carried out on a plurality of samples of fibers originating from textile articles which have been used (for example sheets originating from a hospital, worn clothing, etc.), that such samples release organic compounds at temperatures lower than the temperature at which organic compounds from textile articles which have not been used begin to be released. These may be organic compounds originating from organic residues present in the laundry to be washed (food residues, soil, grease, etc.), which are released at temperatures lower than the temperature of 290°C.An initial temperature lower than the temperature at which organic compounds from natural fibers are first released (290°C) makes it possible to dissociate organic compounds from organic residues from organic compounds from natural and / or chemical fibers as will be shown in the application example below.

[0065] According to one implementation of the invention, the final temperature TF may be between 550 and 850°C, and is preferably 550°C. Indeed, such temperatures make it possible to guarantee that the release of the organic compounds from the chemical fibers is complete.

[0066] According to one implementation of the invention, the sequence of temperatures under an inert atmosphere may comprise a first isothermal plateau at the initial temperature T0, possibly followed by a predetermined thermal gradient so as to raise the temperature of the sample to the final temperature TF. [Fig. 1A] schematically illustrates the evolution of the temperature T as a function of time t of such a sequence of temperatures, having an isothermal plateau at the temperature T0, followed by a thermal gradient until reaching the temperature TF.

[0067] Advantageously, the temperature sequence under an inert atmosphere may comprise a second isothermal stage, optionally in addition to the first isothermal stage, at the final temperature TF. This makes it possible to continue, if necessary, the cracking of the compounds having a cracking temperature close to the final temperature TF of the temperature sequence under an inert atmosphere according to the invention. [Fig. 1B] schematically illustrates the evolution of the temperature T as a function of the time t of a temperature sequence, having two isothermal stages, at temperatures T0 and TF as defined above, and linked together by a thermal gradient.

[0068] According to an implementation of the invention, the isothermal stage(s) of the temperature sequence under an inert atmosphere may have a non-zero predetermined duration (for example, greater than half a minute), preferably between 1 and 5 minutes, and very preferably 3 minutes. Such durations make it possible to consider that the cracking of the compounds having a cracking temperature close to the temperature of the isothermal stage is complete. According to the implementation of the invention in which the temperature sequence under an inert atmosphere according to the invention comprises several isothermal stages and in particular two isothermal stages at temperatures T0 and TF, the duration of an isothermal stage may be different from the duration of the other isothermal stages.

[0069] According to one implementation of the invention, the thermal gradient(s) of the temperature sequence under an inert atmosphere may be between 1°C / min and 50°C / min, preferably between 15°C and 35°C / min, and may very preferably be 25°C / min. Such values ​​constitute compromises allowing the thermal cracking of organic compounds, while limiting the duration of implementation of the process.

[0070] According to the invention, a representative quantity of hydrocarbon compounds (HC) contained in an effluent resulting from said heating is measured continuously (i.e. continuously over time). In other words, during this sequence, the representative quantity of HC released by the sample by thermal cracking of the organic matter and by the thermal decomposition of natural and / or chemical fibers can be measured continuously. The measurement of the representative quantity of hydrocarbon compounds can be carried out by means of a flame ionization detector (FID). It should be noted that such sensors measure a flow of HC, and give values ​​measured in millivolts (mV). Conventionally, a quantity of HC can be determined by determining an area under the curve measured (possibly between predefined temperatures) by these sensors, and by dividing this area by the mass in mg of the sample.Alternatively, other means of measuring the amount of HC may be used.

[0071] According to one implementation of the invention, the temperature sequence under an inert atmosphere according to the invention may be preceded by a phase of temperature rise of the pyrolysis furnace, which may be in the form of a thermal gradient, for example between 1 and 50°C / min, preferably between 20 and 25°C / min, or any other form of temperature rise curve of the pyrolysis furnace. This preliminary phase of temperature rise of the pyrolysis furnace makes it possible to bring the pyrolysis furnace to the initial temperature of the temperature sequence in inert atmosphere according to the invention. This preliminary phase can contribute to starting the thermal cracking of compounds whose cracking temperature is lower than the initial temperature of the temperature sequence under an inert atmosphere according to the invention.

[0072] According to one implementation of the invention, the sequence of temperatures under an inert atmosphere according to the invention may be followed by a phase of lowering the temperature of the pyrolysis furnace, which may be in the form of a thermal gradient, for example between -1 and -50°C / min, preferably between -20 and -25°C / min, or any other form of temperature reduction curve of the pyrolysis furnace. This final phase of lowering the temperature of the pyrolysis furnace makes it possible, if necessary, to complete the thermal cracking of the associated compounds at the final temperature of the sequence of temperatures under an inert atmosphere according to the invention.

[0073] According to the invention, at the end of this step, a curve is obtained representing the quantity of HC released over time during the pyrolysis phase, denoted C(T) thereafter. It is quite obvious for a person skilled in the art to move from a curve representing the quantity of HC released over time to a curve representing the quantity of HC released as a function of temperature, since the sequence of temperatures (evolution of the temperature as a function of time T(t)) is known.

[0074] 2) Determination of the quantity of hydrocarbon compounds released

[0075] During this step, from a curve C ( T ) of the evolution as a function of the temperature of the representative quantity of hydrocarbon compounds released by the sample during heating in an inert atmosphere, we determine: - a quantity of hydrocarbon compounds released by the natural fibers of the sample according to a formula of the type:

[0076] „ ™ [T / CT) (1), and / or QHCN = JTO,7^dr - a quantity of hydrocarbon compounds released by the chemical fibers of the sample according to a formula of the type: QHCC = f^^S^(2)'

[0077] Where:

[0078] - TI is a temperature (called "intermediate temperature of integration of the curve C(T) * or even more simply “intermediate integration temperature” hereinafter) between 390 and 400°C and preferably 390°C,

[0079] - TQ is a temperature (called "initial temperature of integration of the curve C(T) * or even more simply “initial integration temperature” thereafter) included between the initial temperature T0 of the sequence of temperatures according to the invention and the intermediate integration temperature TI, preferably between 280°C and 290°C and very preferably being 290°C,

[0080] - TF' is a temperature (called "final integration temperature of the curve C(T) * or even more simply “final integration temperature” hereinafter) between the intermediate integration temperature TI and the final temperature TF of the temperature sequence according to the invention, preferably between 550°C and 650°C, and very preferably being 550°, and where mech is the mass of the sample.

[0081] In other words, in its most preferred mode, one integrates, with a weighting by the mass of the sample, the curve C(T) between the temperatures which have been identified as characteristic of the release of organic compounds from natural fibers on the one hand (equation (1)), and of organic compounds from chemical fibers on the other hand (equation (2)).Indeed, as discussed in the previous step, the Applicant was able to observe, by means of numerous tests carried out on a plurality of samples of natural fibers of different types (cotton, wool, linen, etc.) and chemical fibers (PET, PA, viscose, etc.), that the natural fibers present in a sample release organic compounds between a temperature at which the organic compounds from the natural fibers start to release, being 290°C, and the intermediate integration temperature TI according to the invention, and that the chemical fibers present in a sample release organic compounds between the intermediate integration temperature TI according to the invention and the temperature at which the organic compounds from the chemical fibers end to release, being 550°C.It is clear that the initial integration temperature T0' (respectively final integration temperature TF') can be chosen higher (respectively lower) than the start (respectively end) temperature of release of organic compounds from natural (respectively chemical) fibers, being 290°C (respectively 550°C) if the curve (j(T) has a peak starting (respectively ending) at a temperature higher (respectively lower) than 290°C (respectively 550°C).Similarly, it is clear that the initial integration temperature T0' (respectively final integration temperature TF') can be chosen lower (respectively higher) than the start (respectively end) temperature of release of organic compounds from natural (respectively chemical) fibers, which is 290°C (respectively 550°C) if the curve c(T) does not show significant values ​​(in other words, almost zero values ​​apart from measurement errors) at a temperature lower (respectively higher) than 290°C (respectively 550°C). In other words, the values ​​of the parameters QHCN and QHCC will in this case be almost unchanged if the start and end temperatures of integration of the curve C{T) are widened.

[0082] This is illustrated in Figure 2, which shows examples of curves of the evolution as a function of temperature of the representative quantity of hydrocarbon compounds related to the mass of the QHC-M sample (unit in mV / mg) released at the end of step 1) applied to the following samples: pure cotton C, pure linen L, PET, viscose V. It can be observed that the end temperature of release of the HC compounds from the samples of natural fibers (cotton C, linen L) is lower than the intermediate integration temperature TI according to the invention, and that the start temperature of release of the HC compounds from the samples of chemical fibers (PET, viscose V) is higher than the intermediate integration temperature TI according to the invention. Thus, it is clear that the intermediate integration temperature TI is a temperature making it possible to distinguish natural fibers from chemical fibers and vice versa.Similarly, it can be observed that the temperature at which HC compounds start to release from the natural fiber samples (cotton C, linen L) is much higher than or equal to the very preferred value of the initial integration temperature (T0'=290°C) described above, and that the temperature at which HC compounds end to release from the chemical fiber samples (PET, viscose V) is lower than or equal to the very preferred value of the final integration temperature (TF'=550°C) described above. In the case of a sample comprising only linen, it can further be deduced from this figure that an integration of the C(t) curve between 290°C and the intermediate temperature would not be necessary since the peak of the C(T) curve associated with linen L starts at a temperature higher than 290°C.Thus, it is understood from this example that the very preferred temperature T0' of 290°C is given for a simplified implementation of the method according to the invention, not requiring an analysis of the curve c(T)-.

[0083] 3) Quantification of natural fibers and / or chemical fibers

[0084] During this step, from the quantities of hydrocarbon compounds released by the natural fibers and / or the chemical fibers of the sample determined in step 2), the following are determined:

[0085] - a mass percentage of natural fibers present in said liquid effluent by means of a predetermined correspondence law relating a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of a sample, and / or

[0086] - a mass percentage of chemical fibers present in said liquid effluent by means of a predetermined correspondence law relating a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of a sample.

[0087] According to a first variant of implementation of the invention, in a step prior to at least step 3), it is possible to determine the correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample at a mass percentage of natural fibers of a sample in the following manner: from a first plurality of reference samples for which a mass percentage of natural fibers is predetermined, the following steps are carried out:

[0088] - for each of the reference samples of the first plurality of samples reference, steps 1) and 2) are applied so as to determine a quantity of hydrocarbon compounds released by said natural fibers for each of the reference samples of the first plurality of reference samples;

[0089] - we determine the correspondence law linking a quantity of compounds hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of a sample by means of a linear regression method applied to the determined quantities of hydrocarbon compounds released by the natural fibers for each of the reference samples of the first plurality of reference samples and to the predetermined mass percentages of natural fibers of these reference samples of the first plurality of reference samples.

[0090] According to a second variant of implementation of the invention, in a step prior at least to step 3), the correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of a sample can be determined in the following manner: from a second plurality of reference samples for which a mass percentage of chemical fibers is predetermined, the following steps are carried out:

[0091] - for each of the reference samples of the second plurality of samples reference, steps 1) and 2) are applied so as to determine a quantity of hydrocarbon compounds released by said chemical fibers for each of the reference samples of the second plurality of reference samples;

[0092] - we determine the correspondence law linking a quantity of compounds hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of a sample by means of a linear regression method applied to the determined quantities of hydrocarbon compounds released by the chemical fibers for each of the reference samples of the second plurality of reference samples and to the predetermined mass percentages of chemical fibers of these reference samples of the second plurality of reference samples.

[0093] [Fig.3] shows an example of a regression line R determined for a plurality of reference samples corresponding to mixtures in various proportions of chemical fibers of different types, the quantity of hydrocarbon compounds QHCC released by each reference sample of which was determined by applying steps 1) and 2) described above, and for which the mass percentage of chemical fibers %FC is known elsewhere. This figure shows a strongly linear behavior between the quantity of hydrocarbon compounds QHCC released by the reference samples of chemical fibers and their mass percentage of chemical fibers %FC, which justifies the implementation of a linear regression method.

[0094] According to a third variant of implementation of the invention, the correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of cotton fibers present in the sample can be defined by the following formula: %F;V = a QHCN

[0095] where a is between 100 and 250. The values ​​of the coefficient a were established by the Applicant by applying the first variant of implementation of the invention described above to a plurality of reference samples corresponding to mixtures of natural fibers in various proportions and an inert material (not releasing hydrocarbon compounds) such as sand.

[0096] According to an implementation according to which the first plurality of reference samples corresponds to mixtures in various proportions of cotton and / or linen, and an inert material, the coefficient a can be between 160 and 190, and can preferably be 179. The values ​​of the coefficient a were established by the Applicant, by applying the first variant of implementation of the invention described above on a first plurality of reference samples corresponding to mixtures in various proportions of cotton and / or linen and an inert material (not releasing hydrocarbon compounds) such as sand. This variant can be advantageously implemented in an industrial laundry, because the textile articles cleaned in this type of structure are essentially made of cotton (work clothes, linen for hotels and restaurants).

[0097] According to a fourth variant of implementation of the invention, the correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers present in the sample is defined by the following formula: %FC = fi. QHCC

[0098] Where / / is between 200 and 600. The values ​​of the coefficient P were established by the Applicant, by applying the second variant of implementation of the invention described above on a plurality of reference samples corresponding to mixtures in various proportions of chemical fibers and an inert material (not releasing hydrocarbon compounds) such as sand.

[0099] According to an implementation according to which the second plurality of reference samples corresponds to mixtures in various proportions of polyester (PET) and / or polyamide (PA) type and an inert material, the coefficient P can be between 360 and 380, and can preferably be 372. The values ​​of the coefficient P were established by the Applicant, by applying the second variant of implementation of the invention described above on a second plurality of reference samples corresponding to mixtures in various proportions of chemical fibers of PET and / or PA type and an inert material (not releasing hydrocarbon compounds) such as sand.

[0100] Thus, the present invention makes it possible, from a quantity of hydrocarbon compounds released during a heating sequence in an inert atmosphere whose minimum and maximum temperatures are predefined, to determine a mass percentage of natural fibers and / or chemical fibers present in a liquid effluent from at least one textile treatment device. These results are obtained from a simple heating in an inert atmosphere, whose minimum and maximum temperatures are defined so as to optimize the energy consumption of the process according to the invention, as well as the implementation time of the process according to the invention (25 minutes maximum). Examples

[0101] The characteristics and advantages of the method according to the invention will appear more clearly on reading the application example below.

[0102] The method according to the invention was applied to a sample consisting of solid residues deposited in the filter of an industrial laundry. The sample was subjected to heating under an inert atmosphere between an initial temperature of 200°C and a final temperature of 650°C.

[0103] [Fig.4] shows the curve of the evolution as a function of the temperature T of the representative quantity of hydrocarbon compounds QHC released during heating under an inert atmosphere. It can be observed that this curve presents three distinct zones:

[0104] - a zone Zl, between 200 and 290°C, corresponding to the release of compounds organic compounds not corresponding to natural and chemical fibers: in fact, the numerous tests carried out by the Applicant on very varied fiber samples show that no textile fiber releases organic compounds below 290°C. These may be organic compounds from organic residues present in the laundry to be washed (food residues, soil, grease, etc.). It is therefore preferable that the HC compounds released in this zone are not taken into account for the mass quantification according to the invention.

[0105] - a zone Z2, between 290°C and 390°C, corresponding to the release of compounds organic from natural fibers, as described above;

[0106] - a zone Z3, between 390°C and 650°C, corresponding to the release of compounds organics from chemical fibers, as described above. It can be observed that the QHC values ​​are almost zero above 550°C.

[0107] Steps 2) and 3) are applied with initial integration temperatures T0' equal to 290°C, intermediate integration temperature TI equal to 390°C, and final integration temperature TF' equal to 650°C, and according to the third and fourth variants described above. It was thus possible to determine that the sample from the industrial laundry comprises:

[0108] - a mass percentage of cotton fibers %FN worth 58.53%

[0109] - a mass percentage of chemical fibers %FC worth 25.53%.

Claims

1. Claims Method for quantifying natural fibers and / or chemical fibers present in a liquid effluent from at least one textile treatment device, from a sample of said liquid effluent and / or a sample comprising at least one filtration residue of said liquid effluent, characterized in that at least the following steps are carried out for said sample: A) said sample is heated in an inert atmosphere according to a sequence of temperatures having an initial temperature (TO) of at most 290°C and a final temperature (TF) of at least 550°C, and at least one representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere is continuously measured; B) from a curve C(70 of the evolution as a function of the temperature of said representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere by said sample, we determine: - a quantity of hydrocarbon compounds released by said natural fibers of said sample according to a formula of the type: QHCN = f”^dT'and / or - a quantity of hydrocarbon compounds released by said chemical fibers of said sample according to a formula of the type: QHCC = J7ï -^dT Where TI is an intermediate integration temperature between 390 and 400°C, TO is an initial integration temperature between said initial temperature (TO) of said temperature sequence and said intermediate integration temperature TI of said curve C(T), TF' is a final integration temperature between said intermediate integration temperature TI and said final temperature (TF) of said temperature sequence, said intermediate integration temperature preferably being 390°C, said initial integration temperature TO preferably being between 280°C and 290°C, and said final integration temperature TF preferably being between 550°C and 560°C, and where mech is a mass of said sample; C) We deduce:

2.

3.

4. - a mass percentage of natural fibers present in said liquid effluent by means of a predetermined correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of said sample, and / or - a mass percentage of chemical fibers present in said liquid effluent by means of a predetermined correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of said sample. Method according to claim 1, in which, from a first plurality of reference samples for which a mass percentage of natural fibers is predetermined, the following steps are carried out: - for each of said reference samples of said first plurality of reference samples, steps A) and B) are applied so as to determine a quantity of hydrocarbon compounds released by said natural fibers for each of said reference samples of said first plurality of reference samples; - said correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers of a sample is determined by means of a linear regression method applied to said determined quantities of hydrocarbon compounds released by said natural fibers for each of said reference samples of said first plurality of reference samples and to the predetermined mass percentages of natural fibers of said reference samples of said first plurality of reference samples. Method according to claim 1, in which said correspondence law linking a quantity of hydrocarbon compounds released by natural fibers of a sample to a mass percentage of natural fibers %FN in said sample is defined by a formula of the type: %FN = a QHCN Where a is a coefficient between 100 and 250. A method according to claim 3, wherein said natural fibers correspond to cotton and / or linen, and wherein the coefficient a is between 170 and 190, and is preferably 179.

5. Method according to one of the preceding claims, in which, from a second plurality of reference samples for which a mass percentage of chemical fibers is predetermined, the following steps are carried out: - for each of said reference samples of said second plurality of reference samples, steps A) and B) are applied so as to determine a quantity of hydrocarbon compounds released by said chemical fibers for each of said reference samples of said second plurality of reference samples;- said correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers of a sample is determined by means of a linear regression method applied to said determined quantities of hydrocarbon compounds released by said chemical fibers for each of said reference samples of said second plurality of reference samples and to said predetermined mass percentages of chemical fibers of said reference samples of said second plurality of reference samples.;

6. Method according to one of claims 1 to 4, in which said correspondence law linking a quantity of hydrocarbon compounds released by chemical fibers of a sample to a mass percentage of chemical fibers %FC present in said sample is defined by a formula of the type: %FC — fi. QHCC Where fi is a coefficient between 200 and 600.

7. Method according to claim 6, in which said chemical fibers correspond to PET and / or PA, and in which said coefficient fi is between 360 and 390, and preferably has a value of 372.

8. Method according to one of the preceding claims, in which said initial integration temperature TW is 290°C.

9. Method according to one of the preceding claims, in which said final integration temperature TF' is 550°C.

10. System for implementing the method according to one of the preceding claims comprising at least one furnace pyrolysis in an inert atmosphere and means of measuring hydrocarbon compounds.

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