Cleaning and decontamination of fibers from used cigarette butts by contact with supercritical fluids and recycling of the decontaminated fibers

Abstract

The present invention relates to an installation (200) for cleaning cigarette butts, said installation comprising a treatment tank adapted to treat the cigarette butts and extract from them fibres to be decontaminated; and decontamination means (100) adapted to decontaminate the fibres by bringing them into contact with a fluid in a supercritical state, known as a supercritical fluid.

Description

[Technical field]

[0001] The present invention relates to the field of butt cleaning, and more particularly to the field of cleaning and decontamination of fibres coming from the filters of smoked butts.

[0002] One of the goals of the present invention is to reduce the impact of smoked butts on the environment by cleaning / decontaminating the fibers derived from butts and recycling these fibers by producing eco-designed products.

[0003] The object of the present invention is therefore a cleaning method and a plant for decontaminating fibres coming from the filters of used cigarette butts using supercritical fluid technology, with the goal of extracting the toxic substances that accumulate during combustion and make the cigarette butts dangerous, in order to purify the fibres of the cellulose acetate filters and to recycle them.

[0004] The object of the present invention also relates to the recycling and reuse of the decontaminated fibers obtained upon completion of said washing.

[0005] The present invention finds many advantageous applications by providing both manufacturers and communities with a technology for decontaminating cigarette butts that is simple to implement and environmentally friendly. [Background technology]

[0006] After smoking, cigarette butts are known to be classified as hazardous waste based on calculated property HP6 (acute toxicity) and property HP14 (ecological toxicity) from ecological toxicity tests.

[0007] The concentration of nicotine in the butt is the primary factor responsible for this classification.

[0008] In addition to their toxicity, butts are one of the most significant waste products in the world, with over 4.3 trillion butts being discarded into nature every year, which represents roughly 40% of the waste in the oceans, for example.

[0009] It should be noted here that cigarette butts decompose in nature after about 15 years, and during this time one cigarette butt can pollute up to 500 liters of water.

[0010] For these reasons, recycling cigarette butts has become a major ecological and environmental issue.

[0011] However, despite this proven toxicity and staggering numbers, the Applicant has determined that, for technical, financial and / or ecological / environmental reasons, very few measures have been developed to date for the implementation of cigarette butt recycling.

[0012] Known inter alia is US Pat. No. 5,399,633 which relates to the recycling of cigarette butts, in which the recycling essentially consists of a water-based washing step.

[0013] Also known is US Pat. No. 5,399,633, which relates to the recycling of waste from tobacco manufacturing and which also uses a water-based washing step.

[0014] Butt decontamination techniques that involve water-based cleaning (by immersion, spraying, wiping, etc.) necessarily require an additional stage to treat and filter the contaminated water used for cleaning.

[0015] This makes the process expensive and tedious.

[0016] Furthermore, the applicant believes that some toxic substances present in cigarette butts are not soluble in water and that the performance associated with this type of technology is not satisfactory.

[0017] Other techniques have also been proposed for the recycling of cigarette butts, such as that proposed in patent application US 2005 / 0133636, which proposes the recycling of cigarette butts by cleaning the fibres from the cigarette butts using natural absorbent materials such as soil to produce sanitary tampons, and which is mainly aimed at improving health conditions in less-privileged countries.

[0018] However, the technical teachings of this document do not apply to cleaning and decontaminating cigarette butts.

[0019] After conducting extensive research on the subject, the Applicant believes that no reliable and efficient solution exists for cleaning and decontaminating cigarette butts to recycle fibres, in particular cellulose acetate fibres, that guarantees cleaning and decontamination on a large scale and at relatively low cost. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] French Patent Application Publication No. 1754267 [Patent Document 2] U.S. Pat. No. 5,504,119 [Patent Document 3] International Publication No. 2019 / 167054 Summary of the Invention [Problem to be solved by the invention]

[0021] The present invention aims to improve the situation as described above.

[0022] More specifically, the present invention aims to overcome at least one of the various drawbacks mentioned above by providing an innovative cleaning and decontamination technique which involves contacting the cigarette butts with a pressurized dense fluid, in particular a fluid in a supercritical state. [Means for solving the problem]

[0023] To this end, according to a first aspect, the object of the present invention relates to a method for cleaning cigarette butts, said method comprising the following steps: - treatment of the cigarette butts by extracting from them the fibres to be decontaminated; and decontamination of the fibres to be decontaminated by contacting said fibres with a pressurized dense fluid, preferably a fluid in the supercritical state, called a supercritical fluid; Includes.

[0024] It should be understood here that cleaning according to the invention consists in cleaning used cigarette butts; in other words, cleaning concerns the filter of the cigarette butt after smoking.

[0025] As indicated in the introduction, smoked cigarette butts have a high nicotine concentration, and it is this nicotine that is meant in this specification as the main toxic component and which therefore should be washed to decontaminate the fibres and allow them to be reused.

[0026] By contacting the fibers to be decontaminated with a pressurized dense fluid, preferably a supercritical fluid, it is possible to extract from said fibers most, or even all, of the toxic substances and malodors accumulated in the cigarette filter that classify the fibers as toxic.

[0027] The pressurized dense fluid (preferably brought to a supercritical state) acts as a strong solvent, particularly for organic compounds including pollutants and contaminants.

[0028] The above-mentioned extraction of toxic substances and malodors accumulated in cigarette filters by pressurized dense fluid techniques (especially supercritical fluids) allows the decontamination of the fibres, after which these fibres become clean and can be reused for new materials and / or other applications.

[0029] Such decontaminated fibers are evaluated, inter alia, for their thermal and / or acoustic properties, their filtration performance and / or their mechanical properties.

[0030] The use of pressurized dense or supercritical fluids is advantageous in that it does not require any post-treatment after decontamination, in contrast to water-based cleaning techniques that require treatment of contaminated wash water.

[0031] Then, by switching the fluid from a pressurized dense state, preferably from a supercritical state to a gaseous state, it can automatically release the pollutants, so that it is usable again and can be recycled continuously. The cleaning therefore produces very little emissions and is carried out in a closed circuit. For example, the decontamination of 30 liters of textile produces only 0.1 liters of emissions that need to be treated, which represents the concentration of the extracted toxic substances. This ratio is extremely interesting and allows the method to be applied on a large scale.

[0032] The fibres from the butts thus decontaminated can then be converted into various forms of semi-finished or finished products, resulting in eco-designed materials that can be used in several fields. It is understood that the level of cleaning and purification of the fibres may vary depending on the field of application, according to the requirements and standards that apply in that field.

[0033] In one advantageous embodiment, the method according to the invention comprises an initial butt collection stage, during which butts are collected.

[0034] Said collection may be carried out by individuals, associations, communities, companies and / or manufacturers, in particular those active in the field of tobacco manufacturing.

[0035] Such collections can therefore be organised at both local and national levels.

[0036] Advantageously, the fibers of the cigarette butts comprise cellulose acetate fibers. The reuse of these cellulose acetate fibers after decontamination is valuable for applications such as: - textile clothing articles (insulating coat stuffing, insulating cushioning, sewing thread, fabrics, wool used in making textile-based garments or articles: mattresses, cushions, duvets, hats, caps, handbags, etc.); - Thermal and / or sound insulation materials (buildings, electronics, automotive: lithium battery insulators for electric vehicles, aviation, shipbuilding, etc.); - Filtration media (liquid, gas, etc.); - Materials for outdoor mulching / geotextiles: fabrics, plates, etc. (decontaminated materials become biodegradable natural fibres that can be used in nature (e.g. at the base of trees)) It is.

[0037] These materials are produced in the form of fiberboards or bulk fibers, according to the standards of the sector under consideration.

[0038] These fibres are also valued in the plastics industry to create new eco-designed solid materials, either blended or not.

[0039] In one advantageous embodiment, the fibres to be cleaned are introduced into the cleaning chamber, preferably during the decontamination step, before contacting.

[0040] Preferably, the chamber is in the form of an enclosure, such as an autoclave.

[0041] Advantageously, during the decontamination phase, the fluid is compressed to a certain so-called supercritical pressure and heated to a so-called supercritical temperature, said supercritical pressure and said supercritical temperature being determined depending on the fluid.

[0042] Preferably, the supercritical pressure is between 0 and 2,000 bar, preferably between 50 and 350 bar, preferably between 280 and 320 bar.

[0043] Preferably, the supercritical temperature is from 0°C to 400°C, more preferably from 15°C to 80°C.

[0044] Thus, one of the aspects of the present invention is to provide effective decontamination by setting, inter alia, pressure and temperature parameters to bring the fluid to a supercritical state that is strong and solvent-rich enough to eliminate (extract) the toxic substances and malodors present in the tobacco fiber after the tobacco is burned.

[0045] The extraction performance of the material depends on the application envisaged for the regeneration of the fibres. It is understood that the parameters relating to pressure and temperature may be varied according to the result of the required fibre purity.

[0046] Advantageously, the fluid is chosen from the following: carbon dioxide, some organic liquids, such as methanol or ethanol, water, tetrafluoroethane, lower alkanes, such as those having 1 to 5 carbon atoms, such as methane, propane, butane, isobutane, and pentane, dihydrogen monoxide, and alkenes, such as ethylene and propylene.

[0047] All of these fluids can be used as pressurized dense fluids in subcritical (wet oxidation) or supercritical states.

[0048] In one advantageous embodiment of the invention, the fluid selected for the decontamination step is carbon dioxide, in which the supercritical temperature is preferably greater than or equal to 31° C. and the supercritical pressure is preferably greater than or equal to 73.85 bar.

[0049] The use of carbon dioxide as a fluid is advantageous in that waste materials such as cigarette butts can be decontaminated with another waste material (carbon dioxide) which is emitted in very large quantities by industry.

[0050] The above temperature (temperature above 31° C.) and pressure (pressure above 73.85 bar) conditions for bringing carbon dioxide into the supercritical state are sufficient and can be reached without problems in an enclosure such as an autoclave.

[0051] Of course, one skilled in the art may select other fluids and / or other pressure and / or temperature parameters for this decontamination operation.

[0052] It should be understood that the degree of extraction and transport capacity of the fluid can be varied by influencing these temperature and pressure parameters. This technique results in a solubilizing fluid with adjustable power, particularly for extracting contaminants from the fibers from the filter.

[0053] Advantageously, a co-solvent is added to the fluid to extract undesirable organic matter from the fibres whilst preserving the quality and technical properties of the fibres.

[0054] The addition of the co-solvent makes it possible to improve this cleaning process by removing from the fibers some of the organic materials present in the fibers.

[0055] It should be understood that the addition of such co-solvents can occur before, during, and / or after contacting the fluid with the fibers to be decontaminated.

[0056] Advantageously, said co-solvent is chosen from dihydrogen monoxide, alcohols, such as aliphatic alcohols having 1 to 5 atoms, such as ethanol, methanol, butanol, aqueous solvents (such as water), terpenes, benzene, cyclohexane and mixtures thereof, ketones, hydrofluoroethers, and all other co-solvents capable of decontaminating undesirable substances present in the fibres.

[0057] Advantageously, an extractant is added to the fluid to extract inorganic substances such as heavy metals from the fibres.

[0058] The addition of the extractant makes it possible to remove some of the inorganic substances present in the fibres from the fibres, improving the performance of the decontamination step.

[0059] It should be understood that such addition of extractant can occur before, during, and / or after contacting the fluid with the fibers to be decontaminated.

[0060] Preferably, said extractant comprises a series of molecules of calixarene type and / or a solution of an agent capable of extracting inorganic substances (complexing agents, chelating agents, antioxidants, buffers).

[0061] The addition of one or more co-solvents may also affect inorganic molecules, and conversely, the addition of one or more extractants may also affect organic molecules.

[0062] The addition of one or more co-solvents and / or one or more extractants during the cycle is preferably pumped using a suitable pump. It is understood that the co-solvents and extractants are selected on a product-specific basis depending on the undesirable substances to be extracted.

[0063] In practice, depending on the product, results may vary with respect to the purity of the fiber desired.

[0064] Thus, parameters (pressure, temperature, flow rate, wash time, etc.) as well as the use or absence of co-solvents and / or extractants can be varied depending on the desired results.

[0065] Advantageously, the decontamination step comprises moistening the fabric prior to contacting.

[0066] Other parameters related to contact with pressurized dense fluid (eg, supercritical fluid) may be considered, i.e., fluid flow rate and / or flow velocity, contact time, etc.

[0067] Advantageously, the contacting step comprises the action of a jet of fluid in the direction of the fibres, said jet causing the fluid to penetrate throughout the material present in the autoclave.

[0068] Preferably, the jet has a velocity of between 1 and 500 meters / second.

[0069] Preferably, the jet has a flow rate of between 1 and 4,000 litres / hour.

[0070] Preferably, the contacting step is carried out for a period comprised between 1 minute and 8 hours, preferably between 15 and 120 minutes.

[0071] Thus, flow rates and wash times can vary depending on the amount of material being processed, the parameters, and the target substance, among other things.

[0072] For example, the fibers may be rotated in a rotating drum within the washing chamber.

[0073] Pressure fluctuations can also be provided by compression-decompression cycles.

[0074] More generally, the pressure, temperature and flow rate of the fluid may remain constant or may be varied during the cleaning cycle.

[0075] Advantageously, the treatment step involves comminution of the butts.

[0076] Preferably, said comminution is carried out after the collection step and, optionally, after a sorting operation, for example in a grinder or a so-called processing vessel.

[0077] The shredded butts are then conveyed along a production line and subjected to multiple processing operations (friction, and / or sieving, and / or cyclone treatment, and / or secondary shredding).

[0078] Advantageously, the treatment step especially comprises screening.

[0079] This operation, or a variation of these operations, has the primary objective of separating the fibers from other waste materials, which may include leaves, ash, and / or tobacco.

[0080] Only the fibers, partly consisting of cellulose acetate, are recovered. The other waste materials (leaves, tobacco, ash) are preferably recycled in the form of compost.

[0081] These treatment operations may be carried out in treatment vessels adapted for this purpose, which may be separate from the autoclave or, in some cases, directly integrated into the autoclave.

[0082] According to a second aspect, the object of the present invention relates to the cleaned (or decontaminated) textiles obtained after the completion of the implementation of the cleaning process described above.

[0083] The fibers thus decontaminated can be reused for many applications, in particular in the construction and clothing sectors, and in any other sector in which this fiber can be utilized.

[0084] According to a third aspect, the object of the present invention relates to a cigarette butt cleaning installation, said cigarette butt cleaning installation comprising: a treatment vessel adapted to treat cigarette butts and extract the fibres to be decontaminated; and - decontamination means adapted to decontaminate said fibres by contacting said fibres with a pressurised dense fluid, preferably a fluid in a supercritical state, called a supercritical fluid; Equipped with.

[0085] In a preferred embodiment, said decontamination means comprises one or several autoclave type washing chambers.

[0086] Preferably, the autoclave is capable of withstanding high pressures, even substantial pressures.

[0087] For example, the volume of the chamber may vary from 0.2 L to 1,500 L, without limitation.

[0088] Several autoclaves may be connected (in series or parallel) and installed in series to transfer the pressurized fluid from one vessel to another, thus conserving the fluid and thus avoiding reconverting it to this state. This allows the flow to be optimized, saving energy and fluid. Thus, the vessels can be emptied and used alternately, which also saves production time.

[0089] Advantageously, the equipment includes means, such as nozzles, piping and / or valves, for injecting the supercritical fluid into one or more chambers.

[0090] Advantageously, said chamber may extend vertically or horizontally.

[0091] It should be noted that the vertical inclination of the chamber facilitates loading / unloading and ensures good propagation of the fluid (carbon dioxide) within the fibers to be decontaminated.

[0092] Preferably, a hermetic door locks each wash chamber.

[0093] Preferably, the nozzles and piping for the inflow and outflow of fluids to and from the washing chamber are equipped with a grid with a fine grid pattern, called a filter grid, to retain fine fibre particles during the discharge of the fluid carrying undesirable substances, preventing fine fibres from being transported during washing and ultimately ending up as extracted undesirable residues at the outlet.

[0094] Preferably, the facility comprises a tank containing a fluid (in liquid state), said tank being connected to said washing chamber.

[0095] Preferably, the fluid is intended to be in a supercritical state.

[0096] Advantageously, said installation comprises heating means and pressurizing means controllable by a central unit, configured respectively to heat the fluid to a predefined supercritical temperature and to compress the fluid to a predefined supercritical pressure, said central unit determining the supercritical temperature and pressure depending on the fluid.

[0097] The installation further comprises an expansion means configured to expand the fluid to continuously separate it from the transported solid and liquid contaminants throughout the cycle in order to recycle the fluid.

[0098] Preferably, said expansion means is located in said installation upstream of said washing chamber, i.e. at the outlet of the chamber.

[0099] These separators allow the separation of fluids from contaminants by changing the state of the fluid through a pressure drop.

[0100] The installation may include a number of successive separators with different and decreasing pressures, which separate all the toxic substances and malodors that have accumulated during transport with the fluid.

[0101] The separator is designed to separate as many toxic substances and odors as possible from the fluid by having the fluid "lick" and rub against the walls as much as possible.

[0102] Preferably, said separators may be of the cyclone type. At the outlet of these separators, the toxic substances and the aromas (malodors) are collected in suitable containers such as vials or bottles.

[0103] At the outlet of the separator the fluid is captured again and reinjected continuously in a closed circuit into the cycle.

[0104] These substances and fragrances are preferably discharged by gravity, thereby avoiding the possibility of the release of hazardous substances.

[0105] A ventilation / extraction device and safety plate system may be installed in the toxic material collection area to ensure collection of toxic concentrates.

[0106] The equipment is sized proportionally to the selected parameters and can accommodate defined parameters (pressure, temperature, flow rate, filtration, etc.) and includes components such as nozzles, hoses, piping, vessels, separators, tanks, pumps, condensers, heater resistors, heater bands, boilers, coolers, sensors, and pneumatic, hydraulic, and mechanical regulators (e.g., flow meters).

[0107] Advantageously, the washing chamber comprises a rotating drum into which the fibres are introduced, said drum being capable of being mounted on a (for example magnetic or mechanical) axis of rotation, thereby enabling said drum to rotate on said axis of rotation.

[0108] According to a fourth aspect, the object of the present invention relates to the use of fibres derived from cigarette butt filters for the manufacture of thermal and / or sound insulation, filters and / or biodegradable plastic articles.

[0109] This makes it possible to produce eco-designed materials based on fibres derived from cigarette butts.

[0110] Preferably, the fibers are cellulose acetate fibers.

[0111] In certain embodiments, the method is carried out to decontaminate the fabric.

[0112] According to a first variant, the method is used to manufacture (thermal or acoustic) insulation plates, such a use being particularly advantageous in the building and / or energy sector.

[0113] In one embodiment, these plates are made by mixing decontaminated fibers from filters with bicomponent materials or other compounds.

[0114] Preferably, the fibers are bonded together by the addition of an adhesive, bonding material, or any other material capable of securing the fibers together.

[0115] Such use for the manufacture of insulation plates is valued not only in the field of HEQ (High Environmental Quality) or VHEQ (Very High Environmental Quality) type constructions, but also in other fields such as the automotive industry, agriculture, aviation, electronics, electrical, etc.

[0116] According to a second variant, the method is used to prepare a textile clothing article, such article being evaluated in particular for its thermal and / or acoustic properties.

[0117] In certain embodiments, the fibers and insulation plates are sewn and / or inserted into the inside of the garment as padding to create an environmentally friendly insulation.

[0118] According to a third variant, the fibres are conditioned again into filters for filtration, mainly for liquid or gas filtration.

[0119] According to a fourth variant, the fibres, either in pure or mixed state, are subjected to plastic processes and plastic deformations to form new solid materials.

[0120] Thus, the present invention provides all parties involved in cigarette butt recycling with an innovative technology that utilizes the properties of supercritical fluids to decontaminate fibers, particularly cellulose acetate fibers.

[0121] Other characteristics and advantages of the invention will become apparent from the following description, with reference to the attached drawings, which illustrate two non-limiting embodiments of the invention, in which: [Brief description of the drawings]

[0122] [Figure 1] FIG. 1 shows the phase diagram of carbon dioxide. [Diagram 2] FIG. 2 shows a schematic diagram of a cleaning facility implementing supercritical fluid technology for cleaning fibers from cigarette butt filters. [Diagram 3] FIG. 3 shows a flow chart of a method for cleaning fibers from cigarette butt filters. [Figure 4] FIG. 4 is a graph showing the change in mass of several samples over time. [Diagram 5] FIG. 5 is a graph illustrating the change in sound absorption coefficient of the first test sample as a function of frequency. [Figure 6] FIG. 6 is a graph depicting the change in sound absorption coefficient of the second test sample as a function of frequency. [Figure 7] FIG. 7 is a graphical representation that makes it possible to classify the sound absorption coefficient as a function of frequency. [Figure 8] FIG. 8 is a graph showing the change in damping exponent of the bulk product as a function of frequency. [Figure 9] FIG. 9 is a graph showing the change in damping index for the backed plate as a function of frequency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0123] A method for cleaning cigarette butts and associated equipment according to one embodiment of the present invention will now be described with reference to Figures 1 to 9.

[0124] As noted in the introduction, cleaning cigarette butts is a problem for both ecological / environmental and economic reasons, with few currently effective technologies available.

[0125] One of the goals of the present invention consists in recovering and decontaminating the fibres present in cigarette butts, and more specifically in cigarette filters, taking into account the ecological / environmental and economic constraints as mentioned above.

[0126] One of the other goals of this document consists in proposing alternative solutions for the recycling and / or reuse of decontaminated textiles.

[0127] This is made possible in the example described below.

[0128] Fibers from cigarette butts are known to adsorb toxic substances and odors during combustion.

[0129] These materials include organic and inorganic materials, and in particular include: -nicotine, -heavy metal, - organic acids (acetic acid and / or tartaric acid), - nitrosamines, - flumetraline, pendimethalin and / or trifluralin, -phenol, -polycyclic aromatic hydrocarbon (PAH), - formaldehyde and acetaldehyde, - dioxins and / or furans, - Anions (chloride, nitrate, phosphate, sulfate, and / or ammonium) It is.

[0130] The cleaning and decontamination of these fibres consists of extracting these toxic substances adsorbed in the fibres during combustion in order to convert the cigarette butts, which are a hazardous waste (classified as HP14: ecological toxicity and HP6: acute toxicity), into a useful unclassified raw material.

[0131] The concept underlying the present invention is to utilize the technology of pressurized dense fluids, particularly supercritical fluids, in removing these materials in order to effectively clean the contaminated filter fibers.

[0132] The use of pressurized dense fluids, particularly supercritical fluids, is an effective emerging technology that has extremely interesting transport properties that can extract toxins from fibers.

[0133] The applicant has observed that supercritical fluid technology is traditionally used for the extraction of aromas (eg coffee or essential oils).

[0134] The technique is also used to dye textiles without the use of water.

[0135] However, to date, the use of such supercritical fluids has not been considered in relation to cleaning and decontaminating smoked butts, and in particular butt fibres.

[0136] The examples described herein use carbon dioxide as the fluid.

[0137] The Applicant believes that the use of carbon dioxide has the advantage that it is an industrial waste product that is produced in large quantities, therefore reusing this waste product proves to be of great interest: carbon dioxide is available at high purity and low cost.

[0138] The process is carbon neutral thanks to the use of carbon dioxide waste generated by industry. Two waste products are used to generate useful raw materials.

[0139] It should be understood by those skilled in the art that other fluids mentioned herein above may be reused in the context of the present invention.

[0140] Thus, FIG. 1 shows the phase diagram for carbon dioxide.

[0141] Such phase diagrams are known to reveal different states of matter depending on different parameters related to the pressure and temperature of the fluid.

[0142] Under normal conditions of temperature and pressure, carbon dioxide can be in a gas, liquid, or solid state. However, carbon dioxide reaches a critical point P c which has P c and Tc Carbon dioxide has a critical pressure and a critical temperature of P c When subjected to pressures and temperatures greater than those of the critical state, it switches to a supercritical state.

[0143] Critical pressure P c Above this temperature any increase in temperature applied to the liquid will result in the formation of a less dense liquid rather than a gaseous state.

[0144] Critical temperature T c Above this pressure, any increase in pressure applied to the gas results in the formation of a (more condensed) supercritical fluid that does not pass through a liquid state.

[0145] In the supercritical state, carbon dioxide is characterized by intermediate behavior between the liquid and gas states and has the following specific properties: - the volumetric mass is higher and therefore similar to that of a liquid; - The diffusion coefficient is between that of liquids and that of gases; - Viscosity is low and similar to that of a gas.

[0146] These various conditions, formations, and parameters are of interest and provide a versatile solvent for affecting a wide variety of materials for extraction.

[0147] Therefore, the fluid reaches its critical pressure P c When compressed beyond its critical temperature T c This section describes a supercritical fluid when heated beyond

[0148] By setting these temperature and pressure parameters, supercritical fluids can be obtained that have interesting transport properties close to those of gases, as well as solvent powers that rival those of liquid solvents.

[0149] It should be noted that applicants have also observed that the properties of cellulose acetate fibers, for example, can be improved by combining a supercritical fluid such as carbon dioxide with the fibers. This contact actually results in a modification of the inherent properties of the polymer. This can reduce the viscosity (glass transition).

[0150] The low viscosity and high diffusion coefficient of carbon dioxide in the supercritical state allows the solvent to penetrate very well into the core of the fiber, enabling effective cleaning. The combination of carbon dioxide's transport properties and efficient extraction allows for thorough cleaning of the material.

[0151] In accordance with the concept of the present invention, carbon dioxide replaces the use of effective (but highly polluting) organic solvents such as hexane, dichloromethane, perchloroethylene, trichloroethylene and chloroform, or the use of aqueous solvents such as water.

[0152] It will therefore be appreciated that the supercritical state of carbon dioxide provides extremely effective transport properties for the damage-free decontamination of fibers, particularly cellulose acetate fibers present in cigarette filters.

[0153] For carbon dioxide, the phase diagram in Figure 1 shows the critical point P c However, the critical temperature T c and a critical pressure P of 73.85 bar or more c This shows that it corresponds to

[0154] By appropriately varying these parameters beyond their critical values ​​(31° C. and 73.85 bar), the carbon dioxide can be brought into a supercritical state and highly effective targeted cleaning can be performed.

[0155] Before proceeding with the actual cleaning itself, the method according to the invention includes a collection step S0.

[0156] This collection step S0 can involve individuals, as well as associations, communities, companies and any other collection parties.

[0157] This is a citizens' approach to the environment. All the above mentioned actors can be considered in such an approach.

[0158] In the example described herein, there is further provided a series of butt processing operations during stage P1, including in particular a sorting step S1_1 to separate butts from any other waste, a crushing step S1_2 and a sieving step S1_3, which may be repeated multiple times in order to extract as much tobacco, ash and leaves as possible.

[0159] Depending on the batch received, a friction step S1_3, a sieving step S1_4 and a cyclone treatment step S1_5 may or may not also be added.

[0160] The sequence of the various steps in phase P1 is aimed primarily at separating the tobacco fibres to be decontaminated from other waste materials such as tobacco leaves, ash and shredded tobacco.

[0161] It should be noted that in the example described here, only the fibres of the filter, which in particular contain cellulose acetate, are retained for the decontamination step P2, the other waste materials being used in a step for the production of compost, which is for example produced according to another process.

[0162] However, a purer compost can also be obtained by subjecting the ash, leaves and tobacco to the same supercritical treatment.

[0163] In the embodiments described herein, these various processing steps are carried out by equipment comprising a production line comprising, in particular, grinders, sieves, and / or processing vessels (not shown herein) implementing cyclones and / or friction means (not shown herein).

[0164] It should be understood that facility 200 does not necessarily comprise the manufacturing line, but may be located remotely (eg, processing performed by a subcontractor).

[0165] The installation 200 further comprises a washing chamber 10 in the form of an autoclave, said chamber 10 being adapted to wash fibres originating from cigarette filters by contacting said fibres with a fluid in supercritical conditions.

[0166] The chamber 10 is thus constructed to contain a fluid in a supercritical state and therefore to withstand high temperatures and pressures.

[0167] In the example described herein, the chamber 10 is an airtight enclosure, preferably made from stainless steel.

[0168] Thus, the first step S2_0 of this decontamination phase P2 comprises the introduction and positioning in the washing chamber 10 of the fibres to be decontaminated.

[0169] Here, the fibers are introduced into a stationary container.

[0170] However, several options can be considered during cleaning in order to optimize and reduce the parameters used in the cleaning chamber. In fact, by combining supercritical techniques with other mechanical, electrical or chemical means, the components required for cleaning can be reduced. To optimize the method, i.e. to reduce the time, the amount of fluids, the pressure and / or the temperature, cleaning can be completed using any of the following components: - a rotating drum (such as a screen or concrete mixer) placed inside the tank, driven by a magnetic or mechanical torque, capable of moving the material to facilitate the diffusion of the supercritical fluid; and / or - a vibration and ultrasound system that combines the benefits of ultrasound with those of supercritical carbon dioxide, making it easier to extract targeted substances; and / or - mechanical compression means, in particular by pneumatic or hydraulic cylinders or worm gears, to compress the fibres and forcibly extract the molecules to be extracted; and / or - a mixer arranged inside to homogenize the wash; and / or a centrifugation system to redirect all the extracted substances to the outside, thereby avoiding their re-adsorption at another location on the fibre; and / or - Electrical means inside the tank to electrically cut the fibres and facilitate their extraction; and / or - Immersion in aqueous solvents during the cleaning cycle (supercritical fluid-liquid configuration) It is.

[0171] All of these modifications can be used alone or in combination. By applying agitation, vibration, compression, tension, or other motions and actions, the washing conditions can be improved or advantageously optimized for any amount of material.

[0172] Of course, these applications remain optional and are not limiting in any way.

[0173] The idea behind the invention is to place these fibres in contact with a fluid in the supercritical state, here carbon dioxide, in a chamber 10 .

[0174] Thus, in this example, there is provided a connection of the washing chamber 10 to a tank 20 containing carbon dioxide.

[0175] To this end, a set of valves, nozzles, and inlet and outlet piping (not shown here) is provided, configured to connect the washing chamber 10 and the tank 20 .

[0176] Preferably, these elements comprise a grid having a fine grid pattern to retain and filter fibrous particles that may be entrained during the discharge of the fluid carrying the undesirable material.

[0177] The grid prevents these fine fibres from being transported out of the chamber during washing and ultimately ending up as an undesirable extracted residue at the outlet.

[0178] It is desirable to bring the fluid to a supercritical state before contacting the fluid with the fibers to be decontaminated.

[0179] In this example, a washing chamber 10 is provided that includes a compression means 30 and a heating means 40, which respectively compress the fluid to a supercritical target pressure P during step S2_1. sc and during step S2_2, the fluid is compressed to a supercritical target temperature T sc The heating element is configured to heat the

[0180] In this example, the compression means 30 and the heating means 40 are controllable by a central unit 50 .

[0181] This central unit 50 thus determines the supercritical temperature T sc and supercritical pressure P sc The apparatus further comprises electronic storage means (not shown here) for storing information regarding settings related to supercritical cleaning, such as:

[0182] In this example, these supercritical temperatures T sc and supercritical pressure P sc corresponds to a temperature above 31° C. and a pressure above 73.85 bar, respectively. These parameters are here related to carbon dioxide, as described above.

[0183] It should be noted here that the energy resources to reach these parameters are extremely low and energy efficient.

[0184] In the example described herein, it is a central unit 50 which controls the compression means 30 and the heating means 40 to bring the fluid to a supercritical state.

[0185] In this example, an additional step S2_3 of wetting the fibers may also be provided.

[0186] This step S2_3 remains optional.

[0187] After the fluid has reached the supercritical state, the decontamination stage P2 comprises a step S2_4 of contacting the supercritical fluid with the fibres to be decontaminated in the autoclave 10. As mentioned above, carbon dioxide in the supercritical state has been shown to be a strong solvent: step S2_4 of contacting such a supercritical fluid with the fibres of the cigarette butt to be decontaminated makes it possible to extract non-polar organic molecules from the fibres, said molecules being mainly formed of long carbon chains with low molar mass (lipids and fatty substances).

[0188] The contacting step S2_4 can be carried out in a number of forms, which can be combined with each other, namely, high pressure vaporization, immersion, jet nozzle, spraying, etc.

[0189] In the examples described herein, a combination of immersion with the action of a jet is provided.

[0190] The cleaning chamber 10 or autoclave is therefore equipped with spraying means (not shown here) adapted to emit a jet of carbon dioxide in the supercritical state.

[0191] In this example, the electronic storage means stores other parameters relating to the cleaning, such as contact time (immersion time), jet flow rate and / or jet speed.

[0192] In this example, it is provided that the jet propelled in the direction of the fibre has a variable speed between 1 and 500 metres / second and a flow rate between 1 and 4,000 litres / hour.

[0193] In this example, it is provided that the contacting step S2_4 is carried out for a period comprised between 1 minute and 8 hours, this period varying depending on the desired cleaning characteristics and the amount of material to be treated.

[0194] In this example, the electronic storage means also stores other parameters related to the contact.

[0195] Pressure and temperature changes according to compression-decompression cycles can be provided, which improve the decontamination performance.

[0196] It is also possible to provide a parameter relating to the rotation speed of the rotating drum.

[0197] It may also operate by irregular motion, or by motion other than rotation (such as a pendulum).

[0198] To improve the performance associated with the decontamination P2, it may also be provided to add a co-solvent to the fluid during step S2_5.

[0199] The addition of a co-solvent (methanol, ethanol, etc.) S2_5 during the decontamination step increases the polarity and selectivity of the wash, which allows also the extraction of polar organic molecules with shorter chains (sugars, ions, etc.).

[0200] In the example described herein, this addition S2_5 is provided between the compression step S2_1 and the heating step S2_2 by a suitable pump. The co-solvent can also be added upstream or downstream of the washing. The choice and use of these so-called co-solvents depends on the target material to be extracted, corresponding to different output criteria.

[0201] It should be noted that the development of chambers operating at high pressures (>350 bar) allows the extraction of increasingly polar molecules without the addition of co-solvents.

[0202] For example, to extract inorganic materials such as heavy metals, the installation 200 can be further configured to add, during step S2_6, a solution of extractable molecules of calixarene type or of an agent capable of extracting inorganic substances (complexing agents, chelating agents, antioxidants, etc.) to the supercritical fluid.

[0203] This supplementary addition S2_6 allows the formation of complexes with inorganic compounds, which allows the simultaneous transport of the inorganic compounds.

[0204] In the example described herein, it is provided that this addition S2_6 is carried out between the compression step S2_1 and the heating step S2_2 by means of a suitable pump, as for step S2_5. The extractant can also be added upstream or downstream of the washing. The choice and use of these so-called extractants depends on the target substances to be extracted, corresponding to the various output criteria.

[0205] The addition of the co-solvent and / or the extractant is carried out by a central unit 50, which controls means 60 adapted to inject the co-solvent and / or the extractant into said fluid by means of a pump.

[0206] At the outlet of the chamber, the fluid is cooled and depressurized during step S3 for transition to a gaseous state (i.e. expansion) by expansion means 70. The expansion of the fluid by these expansion means 70 allows the fluid to be continuously separated from the solid and liquid contaminants being transported.

[0207] The carbon dioxide is then released in gas form by a capture system 80 which serves as a separator between the fluid and contaminants.

[0208] By using several separators in series with successively decreasing pressures, the separation of the fluid and the pollutants can be optimized. Malodorous and toxic substances separate from the fluid under different pressures. It is therefore important that the separation is carried out in different separators with different pressures. During this separation, the fluid "licks" the walls as much as possible, passing close to the walls, thus detaching as many toxic substances and aromas as possible from the fluid. These steps are carried out continuously during the cleaning cycle, and during step S4, this separator 80 discharges the carbon dioxide in gaseous state towards the condenser 90, which during step S5 converts the carbon dioxide in liquid state and returns it to the storage tank 20 for its reuse. The carbon dioxide is recycled and used continuously in a closed circuit.

[0209] This separator 80 discharges contaminants into a suitable separate, isolated container.

[0210] At the end of the cycle, and possibly in additional steps during or after the cycle on the liquid, gaseous or supercritical fluid, multiple filtration or particle / molecule absorption steps can be performed (in addition to the successive separations performed during cleaning and during the switch from the supercritical to the gaseous state) to ensure complete separation of undesirable liquid and / or solid particles that may remain dissolved in the fluid, allowing the recovery of pure supercritical fluid for reinjection into the next cycle.

[0211] Potentially malodorous molecules and VOCs can be captured by passing this fluid through activated carbon, which can be added at the outlet or within the washing chamber, if desired.

[0212] It should be noted that this fluid can be returned to the washing chamber 10 as many times as necessary. The remainder of the contaminated stream is then discharged and treated, as the carbon dioxide is separated from the contaminants by being released and changing to a gaseous state.

[0213] These pollutants are used during the regeneration stage of organic and inorganic substances (hydrocarbons, heavy metals, pesticides, sugars, etc.), for example, such regeneration being carried out according to separate processes.

[0214] The decontaminated fibers are then collected.

[0215] Thus, the technique of textile cleaning with supercritical fluids allows automatic continuous recycling of the fluid by changing its state. Upon leaving the chamber, the fluid switches from the supercritical state to the gaseous state during expansion (loss of volumetric mass), losing its effectiveness as a strong solvent and releasing the undesirable substances (in liquid or solid form) that were transported during the supercritical state. These undesirable substances are collected in dedicated containers for treatment and regeneration.

[0216] Once the physicochemical separation is complete, the fluid can be reinjected into the chamber in a supercritical state. An additional separation step by filtration / absorption can be added to facilitate recovery of residues dissolved in the fluid (in gas, liquid or supercritical state during or after washing) and to purify the fluid in order to restore the full efficacy of its extraction.

[0217] The fluid passes through one or more enclosures (with expansion valves) and one or more separators that can capture and collect any contaminants, thereby cleaning the fluid and making it reusable.

[0218] In the example described herein, the fluid is further passed through an activated carbon filter to trap malodorous molecules and volatile organic compounds. Activated carbon can also be added to the chamber. This step is not required.

[0219] Due to the high volatility of the fluid under atmospheric conditions, the fluid is classified as a dry solvent and therefore no drying step is required.

[0220] The solvent fluid is inert, non-toxic and non-hazardous, and poses no risk of compromising the user's working conditions.

[0221] The present invention provides a technique that does not have the drawbacks of the prior art.

[0222] By adapting supercritical fluid technology and setting parameters, particularly with regard to pressure, temperature, flow rate, contact time, co-solvents and extractants, the present invention allows the decontamination of fibres from the filter of cigarette butts by extracting the odours, organic and inorganic substances that are the reasons why cigarette butts are classified as undesirable waste.

[0223] This extraction is carried out by separating these toxic substances and malodors from the fibrous material. Such a technique provides an ecologically friendly cleaning process that requires very little water and / or chemical solvents.

[0224] Such technology allows very large volumes to be easily managed with very few emissions that must be treated.

[0225] This type of cleaning allows cigarette butts, which would otherwise be completely toxic waste to the environment, to be recycled.

[0226] Recycling of these butts is one of the other advantageous aspects which flows directly from the present invention.

[0227] In fact, decontamination of the fibres makes it possible to reuse them and to take advantage of the technical properties of these fibres, in particular these cellulose acetate fibres, which have interesting acoustic and / or thermal properties.

[0228] Thus, the decontaminated fibers can be used for insulation applications in bulk form or in such a way that the fibers can be arranged and deformed, for example into plates, to create insulation rolls.

[0229] For this purpose, it is preferable to bond and solidify the recycled cellulose acetate fibers together. The bicomponent material is then added to the fibers and mixed. The bicomponent material, of the Trevira 255 2.2 dtex / 6mm: PES copolyethylene type, consists of a core and its periphery. The periphery is more heat sensitive and melts at a lower temperature than the core and the other components, which allows all the fibers to be united. These bicomponent materials are therefore selected according to the characteristics of the recycled fibers. The process works with any type of bicomponent material (possibly organic materials).

[0230] The bonding of the fibers may be accomplished using any type of material, such as an adhesive or bonding material.

[0231] In order to obtain a good dispersion of the materials for good solidification and matching of the plates, it is advisable to carry out a mixing and homogenous integration of the cellulose acetate fibers with the initial bicomponent material (e.g. 15% bicomponent material and 85% cellulose acetate fibers).

[0232] The distribution of the bicomponent material and cellulose acetate fibers can be varied depending on the desired properties of the material (more or less hardness, flexibility, durability, etc.).

[0233] It is understood that the addition of bicomponent materials can increase the durability and stiffness of the material. These plates may be formed by other processes such as gluing, weaving, carding, spinning, pressing, etc. The resulting insulating material can be used for insulation in the construction field as well as in the clothing field and any other field where insulating fibers are needed.

[0234] The decontaminated fibers can also be used to form filters and / or air, water, liquid, or gas filtration systems (municipal, automotive, aviation, hydrocarbon fields, etc.).

[0235] It is still possible to transform the cellulose acetate fibers into a material that can be used in any type of plastic process, especially molding, to convert this recycled material into an article. The cellulose acetate fibers can also be mixed with other materials to create biodegradable products. Furthermore, the cellulose acetate fibers can also be used in the field of composite materials by mixing them with other materials (glues, binders, bicomponent materials, etc.). The cellulose acetate fibers are also used in all types of materials.

[0236] For this application, it is proposed to convert the fibers into a powder or to make them ready for use in plastic processes, so that they can be inserted into machines such as extrusion, injection, molding, thermocompression or even thermoforming machines. It is noted that such materials are transformed in these various processes at temperatures between 80°C and 300°C.

[0237] It should therefore be appreciated that the present invention provides the implementation of supercritical fluid technology for the cleaning and decontamination of fibres originating from cigarette butt filters, such cleaning and decontamination being obtained by contacting said fibres with a carbon dioxide type fluid in the supercritical state.

[0238] By setting the parameters of the autoclave into which the butt fibres are introduced, said fluid can be brought to a so-called supercritical target temperature and pressure that allows good extraction of the toxic substances contained in the fibres, and the process carried out is environmentally friendly and has acceptable economic costs at industrial level.

[0239] The analyses carried out on the fibres decontaminated according to the method of the invention confirm a significant reduction in the nicotine concentration: the residual concentrations of nicotine in the decontaminated cigarette butts no longer result in the classification HP6 "acute toxicity" and HP14 "ecological toxicity" with regard to hazard characteristics, as in the case of the samples before treatment.

[0240] Such decontamination results may lead to the conclusion that the decontaminated fibres are classified as non-hazardous waste.

[0241] Once decontaminated without the use of decontamination water, these fibres can be reused in the form of new ecodesigned materials that are used in bulk form and / or in modified form in several fields, such as fibreboards or bulk fibres according to the standards of the field under consideration: - textile clothing articles (insulating coat stuffing, insulating cushioning, sewing thread, fabrics, wool used in making textile-based garments or articles: mattresses, cushions, duvets, hats, caps, handbags, etc.); - Thermal insulation and / or sound insulation materials (buildings, electronics, automotive: lithium battery insulators for electric vehicles, aviation, shipbuilding and all other sectors where thermal insulation and / or sound insulation is required, etc.); - Materials for outdoor mulching / geotextiles: canvas, plates, bulk, etc. (decontaminated materials become biodegradable natural fibres that can be used in nature (e.g. at the base of trees, etc.)); - Filter media (liquid, gas, etc.) It is.

[0242] These fibres are also valued in the plastics industry to create new eco-designed solid materials, either blended or not.

[0243] It is to be understood that these novel materials may consist of raw materials, semi-finished products, or finished products.

[0244] Other applications are contemplated within the scope of the present invention.

[0245] Such supercritical fluid cleaning techniques have extremely interesting extraction and cleaning properties that are much more effective than the polluting solvents, detergents and aqueous solvents used up to now. Cleaning with such supercritical fluids has the advantage of being completely environmentally friendly, neutral and ecologically favorable, with low emissions (economically interesting since there are almost no residual emissions after cleaning and almost no secondary treatment is required), which allows easy management of large quantities.

[0246] To highlight the important advantages offered by the method of the present invention, analyses were carried out on the following samples: - 20AJ404: batch of unprocessed cigarette butts; - 20AJ405: batches of treated cigarette butts - test 1; -20AJ406: Batches of Treated Butts - Test 2 It is.

[0247] More specifically, the analysis consisted of three batches of ground up cigarette butt samples that may or may not have been subjected to treatment aimed at extracting contaminants.

[0248] For each batch, approximately 100 g of sample was extracted with 5 mL of methanol.

[0249] - Nicotine and phenol analysis results: Nicotine analysis was performed by gas chromatography with flame ionisation detection (GC-FID).

[0250] Phenol analysis was performed by high-performance liquid chromatography (HPLC). Table 1 below shows the results of the quantitative analysis of nicotine and phenol content in the cigarette butts in mg / kg.

[0251] [Table 1]

[0252] - Organic acids and cyanide compounds analysis results: Analysis of organic acids was performed by ion exchange chromatography with conductivity detection after water extraction on approximately 1 g.

[0253] Cyanide analysis was performed by extraction of approximately 1 g and trapping in 30 mL of 1 M sodium hydroxide solution followed by ion exchange chromatography with amperometric detection.

[0254] Table 2 below shows the results of the quantitative analysis of the organic acid and cyanide content in cigarette butts in mg / kg.

[0255] [Table 2]

[0256] - Metal analysis results: Analysis of 24 metals and metalloids, namely aluminum (Al), arsenic (As), boron (B), barium (Ba), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), phosphorus (P), lead (Pb), antimony (Sb), selenium (Se), silicon (Si), titanium (Ti), and zinc (Zn), was performed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after acid digestion (HNO3) of approximately 300 mg samples in a closed microwave oven.

[0257] ICP-OES was used for: (Al, Ba, Ca, Cu, Fe, Hg, K, Mg, Mn, Na, P, Si, Ti, and Zn).

[0258] ICP-MS was used for: (As, B, Cd, Cr, Li, Mo, Ni, Pb, Sb, and Se). Table 3 below shows the results of the quantitative analysis of the metal content in the butts in mg / kg.

[0259] [Table 3]

[0260] - Complementary analysis results: The moisture content of the samples was determined by oven drying (105° C.) to constant weight (Table 4 below).

[0261] Table 4 below shows the results of the analysis of the moisture content of the butt samples.

[0262] [Table 4]

[0263] Due to the small moisture content values, these were not taken into account in the calculations.

[0264] Furthermore, the pH of the aqueous solution in contact with the sample was determined in order to be able to identify the speciation of some metals. The ratio of the mass of the test sample to the volume of water was 1 / 10.

[0265] Table 5 below shows the results of the analysis of the samples for pH.

[0266] [Table 5]

[0267] A pH value corresponding to a slightly basic solution allows the exclusion of alkaline substances such as potash (KOH), soda (NaOH), or lime (Ca(OH)2) present in large amounts (>g / kg).

[0268] Based on the above results, an assessment of the hazard characteristics was carried out, which was carried out according to the XP X 30-489 standard.

[0269] Prior to treatment, the presence of nicotine in the cigarette butts at a concentration of 5,580±51 mg / kg meant the sample was classified as hazardous waste based on the HP6 characteristic "acute toxicity".

[0270] After processing, satisfactory and even very satisfactory results are obtained.

[0271] An iterative approach on two samples 20 AJ 405 (Test 1) and 20 AJ 406 (Test 2) can lead to the conclusion that the first sample after treatment can be classified as non-hazardous waste based on HP4, HP5, HP6, HP7, HP8, HP10, HP11, HP13 and HP14 properties by computational assessment.

[0272] For the two samples, the nicotine concentrations (initially about 5,580 mg / kg) are reduced to 870 mg / kg and 418 mg / kg after treatment, respectively, a reduction sufficient (7-13 times) to no longer qualify for the HP6 characteristic "acute toxicity."

[0273] Thus, once the analysis is completed, the reduction of nicotine concentrations in cigarette butts due to the implemented method can be confirmed, since the residual concentrations of nicotine after treatment do not lead to classification of the HP6 hazard characteristic "acute toxicity", as was the case in the samples before treatment.

[0274] With regard to HP14 properties, tests have also shown that treatment can lead to classification as non-hazardous waste according to HP14.

[0275] To highlight the interesting technical properties of the decontaminated fibres, analyses were carried out to demonstrate their efficacy as sound barriers and technical insulators.

[0276] For this purpose, several samples were prepared, with different numbers, which could be analyzed to determine their different technical properties, including the analysis of the effect of grinding on the fiber properties. "Fiber / mixture / plate.1" means that the material has been milled only once. "Fiber / Mixture / Plate.2": Two grinds "Fiber / Mixture / Plate.3": 3 grinds "Fiber / Mixture / Plate.Powder": Grind until powder form

[0277] -Thermal conductivity properties: This test is aimed at determining the thermal conductivity and heat capacity of a material.

[0278] The device consists of two heat exchanger plates, one fixed and the other movable, insulated at the back. A heat transfer fluid circulates in each plate, the temperature of which is regulated by a thermostatic bath. The bath can be programmed to ensure variation over time. With this setup any temperature can be applied to each of the two main faces of the sample. To measure the temperature of the insulation, two thermocouples are used, which are positioned on the outside of the material to be characterized. Two flux meters are placed on each face to measure the heat flux across the sample.

[0279] The experiment will be conducted in three stages: Step 1: The temperature of each plate is 20°C. Step 2: The temperature of each plate is 25°C. Step 3: One plate is at 20°C and the other plate is at 25°C

[0280] The dimensions of the sample are 30.5 x 30.5 cm. 2and have the following density values ​​as volume mass: Plate No. 3.4: 0.16 g / cm 2 , Plate No. 2.1: 0.13g / cm 2 , Plate No. 1.1: 0.15g / cm 2

[0281] - Specific heat measurement At time t=0, a temperature T=20°C is applied to each side of the plate. This temperature is maintained until thermal equilibrium is achieved. This step is then repeated with T=25°C. Finally, a temperature difference is established by setting T1=20°C and T2=25°C, thereby driving the system to another equilibrium state. Between these two time points, the polystyrene has stored a given amount of thermal energy. The total energy stored (Q) is calculated using the following relationship:

[0282]

number

[0283] - Thermal conductivity measurements: To measure the thermal conductivity, a temperature T=25° C. is applied to the material until an equilibrium state is obtained. During this switch to equilibrium, the electrical conductivity of the recycled material according to the invention can be obtained by the following relationship:

[0284]

number

[0285] Results from the thermal resistance test: [Table 6]

[0286] The results obtained during the experiments confirm that the decontaminated fibres are indeed insulating, since they have a conductivity value of less than 0.06 W / m·K (CF standard NF EN 13162+A1). In fact, the material has an average conductivity value of 0.045 W / m·K. This value is the limit for considering a material as insulating. All samples originating from the decontaminated fibres are therefore considered to be insulating. These conductivity and resistance values ​​are close to the properties of mineral wool. It can also be considered from the above tests that the lower the degree of comminution, the more insulating the material is. This means that there is a relationship between volumetric mass and thermal conductivity. It can therefore be considered to find the optimum volumetric mass / thermal conductivity later for the material according to the invention.

[0287] -Water vapor permeability: The hygrometric function of a material describes the behavior of the material when subjected to large variations in temperature and humidity. It is the material's ability to absorb or reject energy to maintain the thermal comfort of the dwelling. This operation aims to measure and characterize the permeability of recycled materials.

[0288] Protocol: The sample to be tested is placed in the jar. A small amount of water is present at the bottom of the jar to generate humidity. A ring is placed to raise the sample and create an air area (1.2 cm) between the water and the product. This volume is the same for all tests. A seal is formed with a mixture of beeswax and paraffin (60 / 40%) and applied between the jar and the sample to avoid direct transfer between the climatic enclosure and the trapped air. The device is then placed in a climatic enclosure set at a humidity level of 50%. A weighing of the mass is carried out every 24 hours to measure the amount of water evaporated.

[0289] Below is the change in mass as a function of time and the percentage of mass lost.

[0290] [Table 7]

[0291] FIG. 4 provides a graph of the above changes in mass of various products over time.

[0292] The permeability results obtained (and a comparison of the permeability of the various materials) are as follows:

[0293] [Table 8]

[0294] According to the NF EN ISO 10456 standard, the data summarized in the table below are obtained.

[0295] The recycled materials are within the same range as the mixtures described above.

[0296] This material has a high absorption capacity.

[0297] - Acoustic characteristics: The acoustic resistance of a material is an important datum in determining the characteristics of a product.

[0298] Experiments carried out in the laboratory made it possible to obtain the sound absorption coefficient and damping index of the recycled materials.

[0299] Sound absorption coefficient: The sound absorption coefficient defines the ratio of absorbed noise to incoming noise. It varies with the frequency of the sound. The sound absorption coefficient ranges from 0 to 1. The closer a material's sound absorption coefficient is to 1, the more sound absorbing the material is.

[0300] Results obtained after Kundt tube tests in the acoustic laboratory: As shown in Figures 5 and 6, it should be seen that the two products absorb frequencies between 400 and 800 Hertz (Hz) extremely well, with sound absorption coefficients of greater than 0.9.

[0301] It is therefore possible to establish a classification of the sound absorption of products as a function of frequency, as shown in Figure 7.

[0302] From 500 Hz onwards, the coefficient remains above 0.85, i.e. class A, the highest class of sound insulation. These classes are defined by the standard EN ISO 354. This sound-absorbing material makes it possible to reduce reverberation and therefore prevent the transmission of noise.

[0303] Attenuation Index: Expressed in decibels (dB), this is a standardized measurement that characterizes the attenuation index of a building material or product. It represents the amount of noise suppressed by this material or product. The higher the index (Rw) of a material, the more sound-insulating it is.

[0304] The results obtained after the Kundt tube test in the acoustic laboratory are shown in Figures 8 and 9.

[0305] Variation of sound absorption coefficient with frequency and material used: [Table 9]

[0306] Variation of damping index depending on material used and frequency: [Table 10]

[0307] From the above information it can be concluded that the bulk and lined plates are extremely effective and approach the properties of melamine foam used in anechoic chambers (laboratory chambers with walls that absorb sound or electromagnetic waves).

[0308] To conclude the validity of the properties of this recycled material, the inventors have confirmed that the material they have studied, derived from recycled cigarette butts, has interesting properties that can be exploited in many fields, especially for insulation.

[0309] It should be pointed out that, while the above detailed description encompasses several specific embodiments of the present invention, this description is not intended to limit the subject matter of the present invention, but on the contrary, is intended to remove any possible inaccuracies or misinterpretations of the following claims.

Claims

1. A method for cleaning smoked butts, comprising the steps of: - treatment of the cigarette butts to extract cellulose acetate fibres to be decontaminated from said cigarette butts (S1_1, S1_2, S1_3, S1_4, S1_5); and - decontamination of said fibres (S2_0, S2_1, S2_2, S2_3, S2_4, S2_5, S2_6) by contacting said fibres with a pressurised dense fluid, which is in a supercritical state and is called a supercritical fluid (S2_4); A method comprising:

2. The method according to claim 1 , wherein the fibers are pre-introduced into a washing chamber (S2_0).

3. The fluid is subjected to a predetermined so-called supercritical pressure (P ｓｃ ) (S2_1) and a predetermined so-called supercritical temperature (T ｓｃ ) (S2_2), and the supercritical pressure (P ｓｃ ) and the supercritical temperature (T ｓｃ ) is determined as a function of the fluid.

4. The supercritical temperature (T ｓｃ ) is 0°C to 400°C, and the supercritical pressure (P ｓｃ 4. The method of claim 3, wherein the pressure is 0 to 2,000 bar.

5. 5. The method of any one of claims 1 to 4, wherein the fluid is selected from: carbon dioxide; organic liquids such as methanol or ethanol; water; tetrafluoroethane; lower alkanes having 1 to 5 carbon atoms such as methane, propane, butane, isobutane, and pentane; dihydrogen monoxide; alkenes such as ethylene and propylene.

6. The fluid is carbon dioxide, and the supercritical temperature (T ｓｃ ) is 31 ° C. or higher, and the supercritical pressure (P ｓｃ 6. The method of claim 5, wherein the pressure in the pressure vessel is 73.85 bar or more.

7. The method of any one of claims 1 to 6, wherein a co-solvent is added to the fluid (S2_5) to extract organic matter from the fibers.

8. 8. The method of claim 7, wherein the co-solvent is selected from dihydrogen monoxide; alcohols including ethanol, methanol, butanol and other aliphatic alcohols having 1 to 5 carbon atoms; aqueous solvents; terpenes; benzene; cyclohexane and mixtures thereof; ketones; and hydrofluoroethers.

9. The method according to any one of claims 1 to 8, wherein an extractant is added to the fluid (S2_6) to extract heavy metals and other inorganic substances from the fibres.

10. 10. The method according to claim 9, wherein the extractant belongs to the family of calixarene type molecules.

11. The method according to any one of claims 1 to 10, wherein the decontamination comprises moistening (S2_3) the fabric prior to the contacting step (S2_4).

12. The method according to any one of the preceding claims, wherein said contacting step (S2_4) comprises the action of a jet of said fluid in the direction of said fibres.

13. The method of claim 12, wherein the jet has a velocity of from 1 to 500 meters per second.

14. The method of claim 12 or 13, wherein the jet has a flow rate of 1 to 4,000 litres / hour.

15. The method according to any one of claims 1 to 14, wherein said contacting step (S2_4) is carried out for a period comprised between 1 minute and 8 hours.

16. The method according to any one of claims 1 to 15, wherein the processing comprises crushing (S1_2) the cigarette butts.

17. 17. The method of claim 16, wherein the processing comprises screening (S1_4) after the grinding step (S1_2) to separate the fibers from other waste materials, wherein the other waste materials include leaves, ash, and / or tobacco.

18. 18. The method of claim 17, wherein the other waste material is recycled in the form of compost.

19. A method according to any one of the preceding claims, comprising an initial step (S0) of collecting the butts.

20. Washed textiles obtained on completion of the washing method according to any one of claims 1 to 19.

21. An apparatus (200) for cleaning smoked butts, comprising: a treatment vessel configured to treat the cigarette butts to extract cellulose acetate fibres therefrom to be decontaminated; and - decontamination means (100) adapted to decontaminate said fibres by contacting them with a pressurized dense fluid, said to be in a supercritical state, called a supercritical fluid; The facility (200).

22. 22. The installation (200) of claim 21, wherein the decontamination means (100) comprises an autoclave type cleaning chamber (10).

23. 23. The installation (200) according to claim 22, wherein the washing chamber (10) is connected to a tank (20) containing the fluid.

24. The washing chamber (10) comprises heating means (40) and compression means (30) controllable by a central unit (50), the heating means (40) and the compression means (30) respectively being adapted to heat the fluid to a supercritical temperature (T ｓｃ ) and heating the fluid to a supercritical pressure (P ｓｃ ) and the central unit (50) is adapted to compress the fluid to the supercritical temperature (T ｓｃ ) and the supercritical pressure (P ｓｃ 24. The installation (200) of claim 22 or 23, further comprising:

25. The installation (200) according to any one of claims 21 to 24, wherein the washing chamber (10) comprises a rotating drum into which the fibres are introduced.

26. Use of cellulose acetate fibres derived from cigarette butt filters decontaminated by carrying out the cleaning method according to any one of claims 1 to 19 for the manufacture of thermal and / or sound insulation materials, filters and / or biodegradable plastic articles.

27. 27. Use according to claim 26, wherein the insulation material is intended for the manufacture of thermal and / or acoustic insulation plates for construction and / or energy.

28. 27. The use of claim 26, wherein the insulating material is for the preparation of a textile article.

29. 27. Use according to claim 26 for the production of air, gas or liquid filters.

30. 27. Use according to claim 26 for the preparation of a plastic material, in particular a biodegradable plastic material.

Images