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

Abstract

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 (TO) 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 the temperature, of a representative amount of hydrocarbon compounds released by the sample is measured. From predefined initial, intermediate (Tl) and final integration temperatures of said curve, an amount of hydrocarbon compounds released by the natural fibers of the sample and / or an amount of hydrocarbon compounds released by the chemical fibers of the sample is determined. Then, on the basis of predetermined laws of correlation, a mass percentage of natural fibers and / or chemical fibers present in the sample is deduced therefrom.

Description

[0001] METHOD FOR QUANTIFYING NATURAL AND / OR CHEMICAL TEXTILE FIBERS PRESENT IN A LIQUID EFFLUENT

[0002] technical field

[0003] The present invention relates to the field of quantifying textile fibers contained in a liquid effluent. In particular, the present invention may relate to the field of quantifying natural and / or chemical fibers contained in a drain fluid from a textile processing device, such as a washing machine, a laundry (industrial or otherwise), a dry cleaner, a textile dyeing device, or a textile waterproofing device.

[0004] Plastic is ubiquitous in our daily lives, and our clothes are no exception, as approximately 60% of the fibers used in the global textile industry are made from plastics such as polyester (PET), polyamide (PA), or acrylic (PAN). Due to abrasion during washing, these synthetic fibers can break down into microfibers. It is generally accepted that plastic microfibers are fragments of synthetic fibers ranging in length from 1 meter to 5 millimeters. According to recent studies, more than 700,000 plastic microfibers can be released with each use of a domestic washing machine. Discharged into wastewater, they are only partially retained in wastewater treatment plants (WWTPs), and a portion therefore ends up in rivers and then the oceans.It is estimated that 500kT / year of plastic microfibers from washing machines are released globally into the aquatic environment, representing nearly 33% of estimated primary microplastic releases.

[0005] In addition to discharges into aquatic environments, it is important to note that the majority of plastic microfibers captured in wastewater treatment plants end up in the sludge during the initial treatment stages. However, the primary use of this sludge in France, and in most countries, is spreading it on agricultural land to amend and fertilize the soil. These microfibers therefore also end up in the natural environment. A post-treatment solution at wastewater treatment plants to reduce plastic microfiber discharges into the oceans would only solve part of the problem. To be effective, plastic microfiber capture solutions must be deployed as close as possible to the emission sources, that is, at the outlet of textile washing systems.Furthermore, the scientific community agrees on the need to implement standardized and harmonized methods for the identification and quantification of plastics in the environment, and in particular of fibers which are the dominant forms in number in the environment.

[0006] Previous technique The following documents will be cited during the description:

[0007] Dreillard, 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.

[0008] Currently, there is no analytical reference standard for analyzing plastic microfibers. However, regulations concerning these microfibers are being developed for implementation by 2025 and aim to define performance levels and thresholds. The work described in this document (Dreillard et al., 2022) has demonstrated the effectiveness of combining advanced microscopy with artificial intelligence-based image analysis methods to quantify fibers contained in wash water that have been previously deposited on filters. One limitation of this approach has been identified, however: the inability to differentiate between the types of fibers, for example, between cotton and synthetic fibers.

[0009] In general, methods for characterizing plastics and polymers are already known and can be used to identify their presence in a sample such as a liquid effluent: for example, differential scanning calorimetry, thermogravimetric analysis, pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC-MS), or Raman spectroscopy. However, these methods vary in complexity and time.

[0010] For example, Fourier transform infrared microspectroscopy (pFTIR, for micro Fourier Transform Interferometer) is a technique that allows the identification of unknown chemical species by characterizing their composition, size, and quantity. However, this method cannot be used for the quantification and differentiation of microfibers smaller than approximately 20 pm (the detection threshold of the pFTIR method).

[0011] We are also familiar with patent application WO 2022 / 243080 A1, which concerns 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 the 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 followed by 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, PA11, PFA, and PET), distributed in predetermined concentrations, is compiled beforehand.Parameters from the results of the thermal analysis for the sample to be analyzed are compared to those from the sample database for the identification and distinction of polymer families.

[0012] However, this method is designed for samples containing both a porous material and at least one polymer (for example, a sand sample taken from a beach and containing plastic waste), and does not apply to textile fiber samples. Furthermore, this method does not provide a way to distinguish natural fibers from synthetic fibers, let alone quantify the mass of natural and / or synthetic fibers.

[0013] The present invention makes it possible to overcome these drawbacks.

[0014] Summary of the invention

[0015] The present invention relates to a method for quantifying natural and / or synthetic fibers present in a liquid effluent from at least one textile processing device, using a sample of said liquid effluent and / or a sample containing at least one filtration residue from said liquid effluent. The method according to the invention comprises at least the following steps:

[0016] 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;

[0017] B) From a curve C(T) of the evolution as a function of temperature of the said representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere by the said sample, we determine:

[0018] - a quantity of hydrocarbon compounds released by said natural fibers of said sample according to a formula of the type:

[0019] - a quantity of hydrocarbon compounds released by said chemical fibers of said sample according to a formula of the type:

[0020] Where TI is an intermediate integration temperature between 390 and 400°C, TO' 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 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 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 m ech is a mass of said sample;

[0021] C) We can deduce from this:

[0022] - 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 from a sample to a mass percentage of natural fibers from said sample, and / or

[0023] - 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 from a sample to a mass percentage of chemical fibers from said sample.

[0024] According to one embodiment of the invention, starting from a first plurality of reference samples for which a mass percentage of natural fibers is predetermined, the following steps can be carried out:

[0025] - 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;

[0026] - said 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 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.

[0027] Alternatively, the said correspondence law relating a quantity of hydrocarbon compounds released by natural fibers in 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

[0028] Where a is between 100 and 250. According to an embodiment of the invention in which said natural fibers correspond to cotton and / or linen, said coefficient a may be between 170 and 190, and may preferably be 179.

[0029] According to one embodiment of the invention, starting from a second plurality of reference samples for which a mass percentage of chemical fibers is predetermined, the following steps can be carried out:

[0030] - 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;

[0031] - said 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 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.

[0032] Alternatively, the said correspondence law relating a quantity of hydrocarbon compounds released by chemical fibers in a sample to a mass percentage of chemical fibers %FC present in said sample can be defined by a formula of the type: %FC = p. QHCC

[0033] Where p is between 200 and 600.

[0034] According to an embodiment of the invention in which said chemical fibers correspond to PET and / or PA, said coefficient may be between 360 and 390, and may preferably be 372.

[0035] According to one implementation of the invention, said initial integration temperature T0' can be 290°C.

[0036] According to one implementation of the invention, said final integration temperature TF' can be 550°C.

[0037] The invention further relates to a system for implementing the process as described above, comprising at least one pyrolysis furnace in an inert atmosphere and means for measuring hydrocarbon compounds. Other features and advantages of the process according to the invention will become apparent from the following description of non-limiting examples of embodiments, with reference to the accompanying figures described below.

[0038] List of figures

[0039] Figure 1A schematically illustrates the temperature evolution over time of the temperature sequence in the first step of the process according to the invention. Figure 1B schematically illustrates the temperature evolution over time of a variant of the temperature sequence in the first step of the process according to the invention.

[0040] Figure 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 flax, and viscose.

[0041] Figure 3 presents 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 having been determined by application of steps 1) and 2) of the process according to the invention, and for which the mass percentage of chemical fibers is known.

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

[0043] Description of the implementation methods

[0044] The invention relates to a method for quantifying natural fibers and / or chemical fibers present in a liquid effluent from at least one textile processing device, from a sample of the liquid effluent or from a sample comprising at least one filtration residue of said liquid effluent.

[0045] By "natural fibers" or "natural textile fibers", we mean 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 flax) or animal origin (for example wool).

[0046] The term "chemical fibers" or "chemical textile fibers" refers to particles originating from woven, non-woven, or knitted materials (such as clothing or linens) composed of synthetic fibers (i.e., fibers 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 that changes the nature of the fiber) of a natural material (cellulose, wood, plant, etc.). It should be noted that the invention can be applied equally to textile microfibers, that is, fibers with diameters generally ranging from 0.1 to 50 microns.

[0047] The term "textile processing device" refers in particular to a textile washing device, for example, an individual washing machine (or washing machine), for domestic or commercial use, a set of washing machines (for example, in laundries), an industrial laundry (for example, a laundry facility), etc. However, a textile processing device according to the invention generally includes any device that brings 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] The term "liquid effluent from at least one textile treatment device" refers to the liquid resulting 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 as "drainage liquid." Typically, the (micro)fiber content of liquid effluents from textile treatment devices is limited, with levels ranging from 0.1 to 1000 ppm by weight, and generally between 1 and 500 ppm by weight.

[0049] The method according to the invention requires a sample of the liquid effluent or a sample containing at least one filtration residue of the liquid effluent. The directly analyzed liquid effluent sample or the filtered liquid effluent can be obtained from a sample taken at the outlet of the textile processing device's drain line, for example, after each wash in the case of a domestic washing machine, or hourly in an industrial laundry or dry cleaning facility. Such sampling frequencies of the liquid effluent to be analyzed can reliably verify the compliance of a textile processing device's discharges with applicable standards.

[0050] According to one embodiment of the invention, the process according to the invention may include a preliminary step in which the liquid effluent from the textile processing device is filtered by means of filtration devices in order to collect a filtration residue from the liquid effluent. It is understood that the filtration devices must be capable of collecting at least the natural and / or synthetic textile fibers present in the liquid effluent. In one embodiment, the filtration devices comprise a membrane filter. Advantageously, the membrane filter may be made of a material that does not generate particles that could interfere with the quantification of the natural and / or synthetic fibers according to the invention. Most preferably, fiberglass membrane filters may be used.Indeed, these filters are inert with respect to the process according to the invention (they neither contain nor produce natural and / or chemical fibers) and can therefore be introduced, along with their residue, directly into a device suitable for implementing the process according to the invention. Advantageously, a known quantity (for example, 80%) of a material (for example, sand) containing neither natural nor chemical fibers can be added to the filtration residue thus obtained. This is intended to prevent saturating the measurement means with hydrocarbon compounds as described below.

[0051] The process according to the invention can advantageously, but not exclusively, be implemented using 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 oven in an inert atmosphere,

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

[0054] The process 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 process according to the invention may include the following steps:

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

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

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

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

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

[0061] During this step, the sample is heated under an inert atmosphere (such as under a flow of nitrogen, argon or helium) according to a sequence of temperatures in which the 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 has observed, through numerous tests carried out on a variety of natural fiber samples of different types (cotton, linen, wool, etc.), that a temperature of 290°C corresponds to the lowest temperature at which organic compounds begin to be released among all natural fibers. For example, linen has a higher temperature at which organic compounds begin to be released than cotton, which is 290°C. 2As will be described below, this initial temperature is also lower than the temperature at which organic compounds begin to be released from chemical fibers. Similarly, the Applicant has observed, through numerous tests conducted on a variety of chemical fiber samples of different types (PET, PA, viscose, etc.), that a temperature of 550°C is sufficient for the complete release of organic compounds from chemical fibers, regardless of their type. As will be described below, this final temperature is also lower than the temperature at which organic compounds end to be released from natural fibers.

[0063] According to one embodiment of the invention, the initial temperature TO can be between 100 and 290°C, and is preferably 200°C. Indeed, the Applicant has observed, through numerous tests carried out on a variety of fiber samples from textile articles that have been used (for example, hospital sheets, worn clothing, etc.), that such samples release organic compounds at temperatures lower than the initial release temperature of organic compounds from textile articles that have not been used. These may be organic compounds originating from organic residues present in the laundry (food scraps, soil, grease, etc.), which are released at temperatures below 290°C.An initial temperature lower than the start temperature of release of organic compounds from natural fibers (290°C) allows the dissociation of organic compounds from organic residues from organic compounds from natural and / or chemical fibers as will be shown in the application example below.

[0064] According to one embodiment of the invention, the final temperature TF can be between 550 and 850°C, and is preferably 550°C. Indeed, such temperatures ensure that the release of organic compounds from the chemical fibers is complete.

[0065] According to one embodiment of the invention, the temperature sequence under an inert atmosphere may include a first isothermal plateau at the initial temperature T0, optionally followed by a predetermined thermal gradient to raise the sample temperature to the final temperature TF. Figure 1A schematically illustrates the evolution of temperature T as a function of time t in such a temperature sequence, showing an isothermal plateau at temperature T0, followed by a thermal gradient until reaching temperature TF.

[0066] Advantageously, the temperature sequence under an inert atmosphere may include a second isothermal plateau, optionally in addition to the first isothermal plateau, at the final temperature TF. This allows, if necessary, the cracking of compounds with a cracking temperature close to the final temperature TF of the temperature sequence under an inert atmosphere according to the invention to continue. Figure 1B schematically illustrates the evolution of temperature T as a function of time t in a temperature sequence, exhibiting two isothermal plateaus, at temperatures T0 and TF as defined above, and linked by a thermal gradient.

[0067] According to one embodiment of the invention, the isothermal plateau(s) of the temperature sequence under an inert atmosphere may have a predetermined non-zero duration (for example, greater than half a minute), preferably between 1 and 5 minutes, and most preferably 3 minutes. Such durations allow the cracking of compounds having a cracking temperature close to the temperature of the isothermal plateau to be considered complete. According to the embodiment of the invention in which the temperature sequence under an inert atmosphere comprises several isothermal plateaus, and in particular two isothermal plateaus at temperatures T0 and TF, the duration of one isothermal plateau may differ from the duration of the other isothermal plateau(s).

[0068] According to one embodiment of the invention, the thermal gradient(s) of the temperature sequence under an inert atmosphere can be between 1°C / min and 50°C / min, preferably between 15°C and 35°C / min, and most preferably 25°C / min. Such values ​​represent a compromise that allows for the thermal cracking of organic compounds while limiting the implementation time of the process.

[0069] According to the invention, a representative quantity of hydrocarbon compounds (HC) contained in an effluent resulting from said heating is continuously measured (i.e., continuously over time). In other words, during this sequence, the representative quantity of HC released by the sample through thermal cracking of organic matter and thermal decomposition of natural and / or chemical fibers can be continuously measured. The measurement of the representative quantity of hydrocarbon compounds can be carried out using a flame ionization detector (FID). Note that such sensors measure an HC flux and provide values ​​measured in millivolts (mV). Conventionally, the quantity of HC can be determined by calculating the area under the curve measured (possibly between predefined temperatures) by these sensors and dividing this area by the mass in mg of the sample.Alternatively, other means of measuring the quantity of HC can be used.

[0070] According to one embodiment of the invention, the inert atmosphere temperature sequence of the invention may be preceded by a heating phase of the pyrolysis furnace, which may take the form of a thermal gradient, for example, between 1 and 50°C / min, preferably between 20 and 25°C / min, or any other type of heating curve for the pyrolysis furnace. This preliminary heating phase of the pyrolysis furnace brings it to the initial temperature of the inert atmosphere temperature sequence of the invention. This preliminary phase can help initiate the thermal cracking of compounds whose cracking temperature is lower than the initial temperature of the inert atmosphere temperature sequence of the invention.

[0071] According to one embodiment of the invention, the temperature sequence under an inert atmosphere according to the invention can be followed by a phase of lowering the temperature of the pyrolysis furnace, which can 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 decrease curve for the pyrolysis furnace. This final phase of lowering the temperature of the pyrolysis furnace allows, if necessary, the completion of the thermal cracking of the compounds associated with the final temperature of the temperature sequence under an inert atmosphere according to the invention.

[0072] According to the invention, at the end of this step, a curve is obtained representing the amount of HC released over time during the pyrolysis phase, hereafter denoted C(T). It is readily apparent to a person skilled in the art to transform a curve representing the amount of HC released over time into a curve representing the amount of HC released as a function of temperature, since the temperature sequence (evolution of temperature as a function of time T(t)) is known.

[0073] 2) Determination of the quantity of hydrocarbon compounds released

[0074] During this step, from a C(T) curve of the evolution as a function of temperature of the representative quantity of hydrocarbon compounds released by the sample during heating in an inert atmosphere, we determine:

[0075] - a quantity of hydrocarbon compounds released by the natural fibers of the sample according to a formula of the type:

[0076] - a quantity of hydrocarbon compounds released by the chemical fibers of the sample according to a formula of the type:

[0077] Or :

[0078] - TI is a temperature (called the "intermediate integration temperature of the C(T) curve" or more simply the "intermediate integration temperature" hereafter) between 390 and 400°C and preferably 390°C, - TO' is a temperature (called the "initial integration temperature of the C(T) curve" or more simply the "initial integration temperature" hereafter) between the initial temperature TO of the temperature sequence according to the invention and the intermediate integration temperature Tl, preferably between 280°C and 290°C and most preferably 290°C,

[0079] - TF' is a temperature (called "final integration temperature of the curve C(T)" or even more simply "final integration temperature" hereafter) between the intermediate integration temperature Tl and the final temperature TF of the temperature sequence according to the invention, preferably between 550°C and 650°C, and very preferably 550°, and where mech is the mass of the sample.

[0080] In other words, in its much preferred mode, we integrate, 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 of onset of release of organic compounds of natural fibers of 290°C and the intermediate temperature of integration Tl according to the invention, and that the chemical fibers present in a sample release organic compounds between the intermediate temperature of integration Tl according to the invention and the temperature of completion of release of organic compounds of chemical fibers of 550°C.It is quite clear that the initial integration temperature TO' (respectively final integration temperature TF') can be chosen higher (respectively lower) than the start (respectively end) release temperature of organic compounds from natural (respectively chemical) fibers, which is 290°C (respectively 550°C), if the C(T) curve has a peak starting (respectively ending) at a temperature higher (respectively lower) than 290°C (respectively 550°C).Similarly, it is quite clear that the initial integration temperature TO' (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, values ​​that are almost zero within measurement errors) at a temperature lower (respectively higher) than 290°C (respectively 550°C).

[0081] In other words, the values ​​of the parameters QHCN and QHCC will in this case be almost unchanged if we widen the respective start and end temperatures of the integration of the C(T) curve.

[0082] This is illustrated in Figure 2, which shows examples of temperature-dependent curves for the representative quantity of hydrocarbon compounds (QHC-M, unit in mV / mg) released after step 1) applied to the following samples: pure cotton C, pure linen L, PET, and viscose V. It can be observed that the final release temperature of the HC compounds in the natural fiber samples (cotton C, linen L) is lower than the intermediate integration temperature Tl according to the invention, and that the initial release temperature of the HC compounds in the synthetic fiber samples (PET, viscose V) is higher than the intermediate integration temperature Tl according to the invention. Thus, it is clear that the intermediate integration temperature Tl is a temperature that allows for the differentiation of natural fibers from synthetic fibers and vice versa.Similarly, it can be observed that the onset temperature of release of HC compounds from the natural fiber samples (cotton C, flax L) is well above or equal to the highly preferred initial integration temperature (T0'=290°C) described above, and that the final release temperature of HC compounds from the synthetic fiber samples (PET, viscose V) is less than or equal to the highly preferred final integration temperature (TF'=550°C) described above. Furthermore, in the case of a sample consisting solely of flax, it can be deduced from this figure that integrating 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 flax L begins at a temperature above 290°C.Thus, we understand from this example that the highly preferred temperature T0' of 290°C is given for a simplified implementation of the process according to the invention, not requiring an analysis of the C(T) curve.

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

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

[0085] According to a first embodiment of the invention, in a step prior to at least step 3), the correspondence law relating a quantity of hydrocarbon compounds released by natural fibers in a sample to a mass percentage of natural fibers in a sample can be determined as follows: starting from a first plurality of reference samples for which a mass percentage of natural fibers is predetermined, the following steps are carried out:

[0086] - for each of the reference samples of the first plurality of reference samples, 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;

[0087] - we determine the 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 by means of a linear regression method applied to the determined quantities of hydrocarbon compounds released by 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.

[0088] According to a second embodiment of the invention, in a step prior to at least step 3), the correspondence law relating a quantity of hydrocarbon compounds released by chemical fibers in a sample to a mass percentage of chemical fibers in a sample can be determined as follows: starting from a second plurality of reference samples for which a mass percentage of chemical fibers is predetermined, the following steps are carried out:

[0089] - for each of the reference samples of the second plurality of reference samples, 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;

[0090] - we determine 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 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.

[0091] Figure 3 shows an example of a regression line R determined for a plurality of reference samples corresponding to mixtures of different types of chemical fibers in various proportions. The amount of hydrocarbon compounds (QHCC) released by each reference sample was determined by applying steps 1) and 2) described above, and the mass percentage of chemical fibers (%FC) is known for each sample. This figure shows a strongly linear relationship between the amount of hydrocarbon compounds (QHCC) released by the reference samples of chemical fibers and their mass percentage of chemical fibers (%FC), justifying the use of a linear regression method.

[0092] According to a third embodiment of the invention, the correspondence law linking a quantity of hydrocarbon compounds released by natural fibers in a sample to a mass percentage of cotton fibers present in the sample can be defined by the following formula: %FN = a. QHCN where a is between 100 and 250. The values ​​of the coefficient a were established by the Applicant by applying the first embodiment 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.

[0093] According to an embodiment in 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 preferably 179. The values ​​of the coefficient 'a' were established by the Applicant, by applying the first variant of the embodiment of the invention described above to 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, since the textile articles cleaned in this type of facility are essentially made of cotton (work clothes, linens for hotels and restaurants).

[0094] According to a fourth embodiment of the invention, the correspondence law relating a quantity of hydrocarbon compounds released by chemical fibers from a sample to a mass percentage of chemical fibers present in the sample is defined by the following formula: %FC = (F QHCC Where p is between 200 and 600. The values ​​of the coefficient p were established by the Applicant, by applying the second embodiment 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.

[0095] According to an embodiment in which the second plurality of reference samples corresponds to mixtures in various proportions of polyester (PET) and / or polyamide (PA) and an inert material, the coefficient p can be between 360 and 380, and preferably 372. The values ​​of the coefficient p were established by the Applicant, by applying the second variant of the embodiment of the invention described above to a second plurality of reference samples corresponding to mixtures in various proportions of PET and / or PA type chemical fibers and an inert material (not releasing hydrocarbon compounds) such as sand.

[0096] Thus, the present invention makes it possible, from a quantity of hydrocarbon compounds released during a heating sequence in an inert atmosphere with predefined minimum and maximum temperatures, to determine a mass percentage of natural and / or synthetic fibers present in a liquid effluent from at least one textile processing device. These results are obtained from a simple heating in an inert atmosphere, the minimum and maximum temperatures of which are defined 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).

[0097] Examples

[0098] The characteristics and advantages of the process according to the invention will become clearer upon reading the application example below.

[0099] The process 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.

[0100] Figure 4 shows the curve of the evolution as a function of temperature T of the representative quantity of hydrocarbon compounds QHC released during heating under an inert atmosphere. It can be observed that this curve has three distinct zones:

[0101] - a zone Z1, between 200 and 290°C, corresponding to the release of organic compounds not associated with natural or synthetic fibers: indeed, numerous tests carried out by the Applicant on a wide variety of fiber samples show that no textile fiber releases organic compounds below 290°C. These may be organic compounds originating from organic residues present in laundry (food scraps, soil, grease, etc.). It is therefore preferable that the HC compounds released in this zone not be taken into account for the mass quantification according to the invention.

[0102] - a Z2 zone, between 290°C and 390°C, corresponding to the release of organic compounds from natural fibers, as described above; - a Z3 zone, between 390°C and 650°C, corresponding to the release of organic compounds from synthetic fibers, as described above. It can be observed that the QHC values ​​are almost zero above 550°C.

[0103] Steps 2) and 3) are applied with an initial integration temperature TO' of 290°C, an intermediate integration temperature T1 of 390°C, and a final integration temperature TF' of 650°C, according to the third and fourth variants described above. It was thus determined that the sample from the industrial laundry comprises:

[0104] - a mass percentage of cotton fibers %FN equaling 58.53%

[0105] - a mass percentage of chemical fibers %FC equal to 25.53%.

Claims

Demands 1) 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, 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 (T0) of at most 290°C and a final temperature (TF) 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; B) From a curve C(T) of the evolution as a function of temperature of the said representative quantity of hydrocarbon compounds released during said heating in an inert atmosphere by the said sample, we determine: - a quantity of hydrocarbon compounds released by said natural fibers of said sample according to a formula of the type: - a quantity of hydrocarbon compounds released by said chemical fibers of said sample according to a formula of the type: 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 m ech is a mass of said sample; C) We can deduce from this: - a mass percentage of natural fibers present in said liquid effluent by means of a predetermined correspondence law linking a quantity of compounds hydrocarbons released by natural fibers from a sample at 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 from a sample to a mass percentage of chemical fibers from said sample. 2) A method according to claim 1, wherein, starting 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 relating 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. 3) A method according to claim 1, wherein said correspondence law relating a quantity of hydrocarbon compounds released by natural fibers in 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. 4) A method according to claim 3, wherein said natural fibers correspond to cotton and / or flax, and wherein the coefficient a is between 170 and 190, and is preferably 179. 5) A method according to any one of the preceding claims, wherein, starting 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 relating 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) A method according to any one of claims 1 to 4, wherein said correspondence law relating a quantity of hydrocarbon compounds released by chemical fibers in a sample to a mass percentage of chemical fibers %FC present in said sample is defined by a formula of the type: %FC = p. QHCC Where p is a coefficient between 200 and 600. 7) A method according to claim 6, wherein said chemical fibers correspond to PET and / or PA, and wherein said coefficient p is between 360 and 390, and preferably equals 372. 8) A method according to any one of the preceding claims, wherein said initial integration temperature T0' is 290°C. 9) Method according to any one of the preceding claims, wherein said final integration temperature TF' is 550°C. 10) System for implementing the process according to one of the preceding claims comprising at least one pyrolysis furnace in an inert atmosphere and means for measuring hydrocarbon compounds.

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