WO2024216338A1

WO2024216338A1 - Method for separating fluoropolymer layers and/or glass from a substrate

Info

Publication number: WO2024216338A1
Application number: PCT/AU2024/050371
Authority: WO
Inventors: Massoud SOFI; Zipeng ZHANG; Yilas SABRI; Mohammad Al Kobaisi; Paramita KOLEY; Neeraj Das
Original assignee: Elecsome Pty Ltd
Current assignee: Elecsome Pty Ltd
Priority date: 2023-04-18
Filing date: 2024-04-18
Publication date: 2024-10-24
Anticipated expiration: 2025-10-18
Also published as: AU2024259205A1

Abstract

The following disclosure relates to a method for separating fluoropolymer layers from a substrate, the method comprising: contacting the substrate with an ionic liquid comprising an organic acid and an organic base to dissolve at least one layer of the fluoropolymer from the substrate. The disclosure further relates to a method of dismantling solar panels for recycling using said method, as well as a method for producing glass fines from photovoltaic glass, comprising: milling the photovoltaic glass to produce glass fines, wherein at least half the glass fines have a particle size of less than 83 µm, and optionally using said glass fines in building materials.

Description

METHOD FOR SEPARATING FLUOROPOLYMER LAYERS AND/OR GLASS FROM A SUBSTRATE Technical Field The present disclosure relates to a method for separating fluoropolymer layers and/or glass from a substrate, for example in the separating and/or recycling of polyvinyl fluoride (PVF) or polyvinylidene fluoride (PVDF) and glass covers from solar panel back- sheets. Background of the Disclosure Fluoropolymers are fluorocarbon based polymers such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymer (PFA) which exhibit a number of useful qualities such as high chemical resistance, thermal stability, low surface energy, high volume and surface resistivity and low coefficient of friction. This makes them advantageous in a number of industries and application, especially as coatings or liners on architectural, automotive and aerospace wall and floor panels, cooking surfaces, and surgical surfaces. While their chemical stability makes them useful in these applications, it poses an issue when fluoropolymer coated substrates are disposed of. One of the main concerns with the disposal of fluoropolymers is the release of perfluorinated compounds (PFCs). PFCs have been found to persist in the environment for long periods of time and can be toxic to wildlife and humans. They are also capable of bioaccumulating in the food chain, which means that their concentrations can increase as they move up the food chain. Some fluorinated polymers are not biodegradable and can persist in the environment for centuries, potentially causing long-term harm to ecosystems. When fluoropolymer waste is pyrolyzed or incinerated, the heat can cause the breakdown of the PFCs into smaller, more toxic compounds that can be released into the air and potentially contaminate the surrounding area. This can lead to air pollution and negative impacts on human health and the environment. In addition to the release of toxic compounds, the incineration of fluoropolymer waste can generate ash and other by-products that may be hazardous and require proper disposal. One application where fluoropolymer waste is becoming a growing concern is in Photo-voltaic systems. Photo-voltaic systems, commonly referred to as solar panels or solar PV, are an increasingly popular method of power generation, owing in part to technological advances in solar panel efficiency, the low relative cost of installation, as well as the non- polluting and renewable nature of the generation. As these photo-voltaic systems age, are damaged, and/or are replaced with newer, more advanced panels, the older panels are decommissioned, generating waste. Currently, the lifespan of a solar panel is somewhere between 20 and 30 years. It is expected that by 2050, up to 78 million tonnes of photo-voltaic panel waste will have been generated globally. Accordingly, there is a high demand for an environmentally friendly way to recycle or repurpose the decommissioned panels. A number of solar panel technologies exist, for example but not limited to monocrystalline, polycrystalline, ribbon, amorphous silicon-based cells, thin-film based cells such as copper indium gallium and cadmium telluride cells, and other emerging technologies such as perovskite cells. Regardless of the technology being used, solar panels typically have a similar design, consisting of a solar cell which produces a photo-voltaic effect, that is to say the conversion of light into electricity (the configuration and constituent materials being dependent on the specific technology), as well as metals such as aluminum, silver, copper alloys, and silicon alloys. A busbar which is typically tin coated copper with lead/tin soldering is also used to connect and channel the generated electricity. The cell and busbar are encapsulated in a polymer such as EVA and situated between a front glass panel and a back- sheet. The back-sheet is typically a PET/PVF or PVDF polymeric laminate, and a common choice is the DuPont™ Tedlar®-polyester-Tedlar® (TPT) back-sheet, which consists of a polyester film sandwiched between two layers of PVF film. Another commonly used back- sheet is DuraShield® KPE, which only uses a single layer of PVDF film on the air side of the polyester, with an adhesive layer instead on the cell side. The front glass, photo-voltaic cells sandwiched between EVA layers and the back-sheet assembly are attached to a frame, usually aluminium, with an adhesive. The panel is also connected to a junction box for connection to the electrical grid. An issue that arises when attempting to recycle solar panels is the removal and separation of the PVF, PVDF, or other fluoropolymer component of the back-sheets when dismantling solar panels. The purpose of the back-sheet is to protect the back of the solar panel from environmental elements as well as to provide insulation. Accordingly, high wear and degradation resistant fluoropolymers such as PVF and/or PVDF are a popular choice for at least the outer layer of the back-sheet. As a result, the fluoropolymers are hard to separate from the polyester film owing to its chemical and physically resistive properties. There are three main existing methods of processing the PVF backsheet when recycling decommissioned solar panels: incineration (heating typically between 750-950°C), pyrolysis (heating typically between 300-500°C), and landfill disposal. All of these processes cause issues. Incinerating PVF produces toxic contaminants including hydrogen fluorides, fluoralkanes and particulate matter, pyrolysis similarly releases fluorine and fluorine products on heating, and additionally retains hazardous compounds in the char and oil produced by pyrolysis, and storing the PVF sheets in landfill risks the leaching of toxic products into the surrounding environment and water. Similar issues arise in the recycling and/or disposal of other applications of fluoropolymer coatings. Fluoropolymers such as PVF and PVDF are widely used across a number of industries due to their durability and strong chemical resistance, for example in wall panels, signage, and window coverings. There thus exists a need to address fluoropolymer waste, such as PVF and PVDF films, across a range of these industries in a way that is comparatively environmentally friendly. Some attempts have been made to dissolve fluoropolymers under supercritical conditions (that is to say, high temperatures and pressures) in organic solvents. For example, PVF has been found to dissolve in CH2F2 at temperatures above 180°C and pressures over 1500 bar, and in dimethyl ether (DME) at temperatures over 130°C and pressures over 550 bar. The required heating and pressure to dissolve PVF using this method is both costly and difficult. There thus exists a need to find an alternative method of separating out fluoropolymers from substrates, for example from the back-sheets of solar panels. A further issue with the recycling of solar panel waste, and indeed waste glass in general, is the recycling of the front glass panels. Waste glass is typically crushed and the products are generally categorized into two streams: furnace ready cullets and non-furnace ready fines. Furnace ready cullets consist of the glass pieces typically larger than 8 mm in size which can be easily separated from contaminants such as bottle tops and wrappers, and can be economically recycled into other glass products. Non-furnace ready glass fines, however, which are the glass pieces smaller than 8 mm, are much harder to recycle. The small size of the particles means that the contaminants cannot easily be removed, which in turn means that the glass-fines may damage the furnace and/or produce a lower quality recycled glass product. Glass panel waste from solar panels are often contaminated with remnants from the other components of the solar panel, and the glass panels typically struggle to be separated from the solar panels into furnace ready cullets. Additionally, the remnants of other components of the solar panel which are crushed with the glass panel may introduce elements not found in typical recycling glass processes. With no easy recycling stream or use for these glass panels, they often end up in landfill or otherwise not being recycled. There thus exists a need to find a method for recycling waste glass, such as the glass front panels of solar panels, which is unsuitable for crushing into cullets, or glass fines created as a by-product of the crushing process. Summary of the Invention According to a first broad aspect, there is provided a method for separating fluoropolymer layers from a substrate, the method comprising: contacting the substrate with an ionic liquid comprising an organic acid and an organic base to dissolve at least one layer of the fluoropolymer from the substrate. In some embodiments, the method further comprises contacting the substrate with an organic solvent prior to contacting the substrate with an ionic liquid. In some embodiments, the substrate is contacted with a mixture comprising the ionic liquid and an organic solvent. In some embodiments, the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:100. In some embodiments, the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:10. In some embodiments, the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:3. In some embodiments, the organic solvent is chosen from dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or tetrahydrofuran (THF). In some embodiments, the organic acid in the ionic liquid is chosen from acetic acid (AcOH) or toluenesulfonic acid (PTSA). In some embodiments, the organic base is chosen from triethylamine (TEA) or tributylamine (TBA). In some embodiments, contacting the substrate with an ionic liquid is carried out at between approximately 20°C and 120°C. In some embodiments, contacting the substrate with an ionic liquid is carried out at between approximately 50°C and 90°C. In some embodiments, contacting the substrate with an ionic liquid is carried out at between approximately 60°C and 70°C. In some embodiments, contacting the substrate with an ionic liquid is carried out for between 5 and 40 minutes. In some embodiments, contacting the substrate with an ionic liquid is carried out for between 5 and 25 minutes. In some embodiments, contacting the substrate with an ionic liquid is carried out for between 5 and 10 minutes. In some embodiments, the method further comprises cooling the ionic liquid or mixture to form solid fluoropolymer material. In some embodiments, the fluoropolymer separated from the cooled ionic liquid or mixture is washed with water, methanol, and/or acetone following separation. In some embodiments, the fluoropolymer is PVF or PVDF. In some embodiments, the substrate is a back-sheet for a solar panel. In some embodiments, the back-sheet includes an outer layer of a fluoropolymer on one side of a polyester film and an inner layer of a fluoropolymer on an opposing side of the polyester film; and wherein contacting the back-sheet with an ionic liquid dissolves the outer layer of the fluoropolymer; the method further comprising: washing the back-sheet; depolymerising the polyester film of the back-sheet; and contacting the back-sheet with the ionic liquid a second time to dissolve the inner layer of the fluoropolymer. In a second broad aspect, there is provided a method of recycling glass from a photovoltaic cell, comprising: separating glass components from the photovoltaic cell; and milling the glass components to produce glass fines. In some embodiments, the milling is in the form of vortex milling. In some embodiments, the vortex milling is in the form of vortex oscillation milling. In some embodiments, the method further comprises: filtering out at least one of the following elements from the glass fines: Fe, Ti, Zn, Co, Pb, Cd, Cu, Ag, Yt, Gd, Yb, and/or In. In some embodiments, the method further comprises adding a surface modifying agent to the glass fines. In some embodiments, the glass fines are used as a replacement for a filler material or fine aggregate in a building material. According to a third aspect, there is provided a method of producing a building material from photovoltaic glass, comprising: milling the photovoltaic glass to produce glass fines; and combining the glass fines with at least a cement and water to form a building material. In some embodiments, the glass fines are used as a filler material in the building material. In some embodiments, the glass fines comprise approximately between 20 and 80 wt% of the total filler in the building material. In some embodiments, the glass fines comprise approximately between 20 and 50 wt% of the total filler in the building material. In some embodiments, the building material is a concrete or a mortar. In some embodiments, the glass fines are used as a sand replacement in the concrete or mortar. In some embodiments, the glass fines are combined with a water reducer. In some embodiments, the water reducer is added in an amount between approximately 1.4 and 3 kg/m3. According to a fourth aspect, there is provided a building material including glass fines produced from milled photovoltaic glass as a filler or fine aggregate replacement. In some embodiments, the building material is made using the method of the third aspect. According to a fifth aspect, there is provided a method for separating a solar panel into recyclable components, the solar panel comprising: a frame and junction box; a glass panel; a solar cell sandwiched between layers of ethylene vinyl acetate (EVA); and a back- sheet comprising a layer of polyvinyl fluoride (PVF) or polyvinylidene fluoride (PVDF) and a polyester film; wherein the method comprises: contacting the back-sheet with an ionic liquid comprising an organic acid and a trialkyl amine to dissolve at least one layer of PVF or PVDF from the back-sheet. In some embodiments, contacting the back-sheet with an ionic liquid is carried out according to the method of any one of claims 1 to 20. In some embodiments, the method further comprises: separating the glass panel from the solar panel; and milling the glass components to produce glass fines. In some embodiments, the glass fines are used to produce a building material according to the third aspect. In some embodiments, the method further comprises: mechanically separating the frame and junction box from the solar panel prior to any other steps. In some embodiments, the method further comprises: incinerating the solar cell and EVA layers; sieving the incinerated solar cell to separate glass from photo-voltaic fragments. In some embodiments, the method further comprises: using high shear homogenizers and/or centrifugation to separate the solar cell and EVA layers into EVA gel and photo-voltaic fragments. In some embodiments, the method further comprises: separating the photo-voltaic fragments into separate metal components and silicon components by electrowinning. Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the inventions disclosed. Brief Description of the Figures The present disclosure will become better understood from the following detailed description of various non-limiting embodiments thereof, described in connection with the accompanying figures, wherein: FIGURE 1 shows an exploded diagrammatic view of a typical silicon-based solar panel and its components. FIGURE 2 shows a diagrammatic view of a typical back-sheet for a solar panel. FIGURE 3 shows a diagram of an embodiment of the method of the present invention. FIGURE 4 shows the FTIR spectra for three experimental ionic liquids. FIGURE 5 shows three SEM images of PVF obtained from different volumetric ratios of [PTSA]/[TBA]-DMF mixtures. FIGURE 6 shows three SEM images of PVF obtained from different volumetric ratios of [AcOH]/[TBA]-DMF mixtures. FIGURE 7 shows three SEM images of PVF obtained from different volumetric ratios of [AcOH]/[TEA]-DMF mixtures. FIGURE 8 shows two SEM images of PVF obtained from an embodiment of the present method following an acetone wash. FIGURE 9 shows four TEM images of PVF obtained from an embodiment of the present method following an acetone wash. FIGURE 10 shows the FTIR spectra for PVF pre and post extraction from a solar panel. FIGURE 11A and 11B show SEM images of two batches of solar panel waste glass. FIGURE 11C and 11D show elemental maps of the two batches of solar panel waste glass in FIGURES 11A and 11B respectively. FIGURE 12 shows the XRD spectra for two batches of solar panel waste glass. FIGURE 13 shows the compressive strength at 3, 7, and 28 days for a number of concrete mixes using solar panel waste glass as a sand replacement. FIGURE 14A and 14B show SEM images of untreated and treated glass particles respectively. FIGURE 15 shows the compressive strength at 3, 7 and 28 days for mortar mixes using treated and untreated solar panel waste glass as a sand replacement. Detailed Description The inventors have found that fluoropolymer layers may be removed from a substrate using an ionic liquid comprising an organic acid and an organic base (such as a trialkyl amine) at less than supercritical conditions. Otherwise stated, the present method allows the dissolution of fluoropolymers such as PVF or PVDF from a substrate under mild conditions by contacting the fluoropolymer layer with an ionic liquid. Preferably, this process is carried out at a temperature between approximately 20°C and 120°C for a time period of between approximately 5 and 40 minutes. In especially preferred embodiments, the heating temperature is between approximately 50°C and 90°C and the time period is between approximately 5 and 25 minutes. In particularly preferred embodiments, the heating temperature is between approximately 60°C and 70°C and the time period is between approximately 5 and 10 minutes. This process can be improved by additionally using an organic solvent, such as DMF, DMSO or THF to swell the fluoropolymer and prime it for dissolution. This can be carried out either in two steps: immersing the substrate in the organic solvent and then in the ionic liquid; or in one step where the substrate is immersed in a mixture of the organic solvent and ionic liquid. The inventors have found that the ratio of ionic liquid to organic solvent may be between approximately 1:1 and 1:100 while still successfully separating fluoropolymer layers from the substrate. Preferably, the ratio of ionic liquid to organic solvent is between approximately 1:1 and 1:10, and even more preferably between 1:1 and 1:3. While DMF, DMSO and THF are preferred organic solvents, it will be understood by a person skilled in the art that other organic solvents may also be suitable for this purpose provided they cause swelling in the fluoropolymer layer. Unlike existing methods of separating fluoropolymers from substrates, where the layer is burnt or pyrolyzed off the substrate, the present method allows the recycling of fluoropolymer material in solution with the ionic liquid. The liquid may be cooled following the dissolution of fluoropolymer material in order to separate out the fluoropolymer in the form of microparticles. The present method also avoids the possible release of toxic contaminants into the atmosphere and environment generated upon incineration, pyrolysis, or landfill storage. Further, the substrate may, where appropriate, also be recycled as part of this method. For example, in the case where the substrate is a polyester film or similar polymer substrate, this layer may also be depolymerized and recovered using any known means. Embodiments of the method which include this process result in even less waste being generated. One common application where this process may be advantageous is in the recycling and end of life management of solar panels. A diagram of a typical solar panel is shown in FIGURE 1. The solar panel 1 comprises a frame 2, attached to the rest of the panel via frame adhesive 3; a glass panel 4, which in this example is a tempered low-Fe cover glass with a thickness of 3 mm; a first polymeric encapsulation film 5 (which in this example is ethylene-vinyl acetate (EVA)), a solar cell 6 (which in this example is a monocrystalline silicon photo-voltaic cell); a second polymeric encapsulation film 7 (also EVA in this example), and a back-sheet 8. Common commercial choices for this back sheet include Tedlar™-polyester- Tedlar™ (TPT) by Dupont™ which consists of a 250 µm thick layer of polyethylene terephthalate (PET) film between two layers of 38 µm thickness PVF film (Tedlar™). A similar product used less frequently includes only a single layer of PVF film on one side of the PET film. The solar panel also includes a junction box 9 in electrical communication with the solar cell 6. A number of back-sheets are commercially available which use at least one fluoropolymer. FIGURES 2A to 2F show some common configurations of back-sheets. FIGURE 2A shows a schematic diagram representing a Tedlar™-polyester- Tedlar™ (TPT) back-sheet, with a first layer of PVF 211, glued by an adhesive 212 to a PET film 213. The PET film 213 is glued by an adhesive 214 to a second layer of PVF 215. FIGURE 2B shows a schematic diagram representing a Kynar™-polyester- Kynar™ (KPK) back-sheet, which is similar to the TPT film of FIGURE 2A with the exception that the PET film 223 is glued by adhesive 222 to a PVDF film 221 on a first side, and by adhesive 224 to a PVDF film 225 on the other side. FIGURE 2C shows a schematic diagram representing a Kynar™-polyester-fluorine (KPF) back-sheet. In this back-sheet, a PVDF film 231 is glued by an adhesive 232 to a PET film 233. The opposing side of the PET film 233 to the PVDF film 231 has been fluorinated to form a fluorine coating 234. FIGURE 2D shows a schematic diagram of a Tedlar™-polyester-polyEthylene vinyl acetate (TPE) back-sheet. This back-sheet comprises a PVF film 241 glued by adhesive 242 to a PET film 243 which is glued by adhesive 244 to a polyethylene vinyl acetate (PEVA) film 245. FIGURE 2E shows a schematic diagram of a Kynar™-polyester-polyEthylene vinyl acetate (KPE) back-sheet. This back-sheet comprises a PVDF film 251 glued by adhesive 252 to a PET film 253 which is glued by adhesive 254 to a polyethylene vinyl acetate (PEVA) film 255. FIGURE 2F shows a schematic diagram of a Tedlar™-polyester-fluorine (TPF) back-sheet. In this back-sheet, a PVF film 261 is glued by an adhesive 262 to a PET film 263. The opposing side of the PET film 263 to the PVF film 261 has been fluorinated to form a fluorine coating 264. While the preparation of each of these back sheets for the present method may differ, they will all involve exposing the fluoropolymer surfaces to be contactable with the ionic liquid. For back-sheets with two layers of fluoropolymers, such as shown in FIGURE 2A and FIGURE 2B, the back sheet may be separated from the rest of the solar panel in order to enable both layers to be contacted with ionic liquid in a single step. In the following, specific reference will be made to PVF films for ease of understanding. A person skilled in the art will readily understand that this is not intended to limit the invention to said films, and the process may be applicable to other fluoropolymers, such as but not limited to PVDF as also commonly used in solar panel back-sheets In some embodiments, it may be advantageous to separate the back-sheet from the remainder of the solar panel. After stripping the frame and junction box from the panel by mechanical or other known means, the remaining elements of the panel can be subjected to a toluene treatment in order to peel the back-sheet away from the EVA encapsulated solar cell. One benefit of this step is that it exposes the cell-side PVF layer, enabling the ionic liquid treatment of both the cell-side and air-side PVF layers in a single step. This may assist in the more complete recycling of the solar panel compared to existing methods. The PVF will be dissolved in the ionic liquid and can then be separated on cooling of the liquid to produce solid PVF which can then be recycled into new products. Similarly, the polyester substrate can be depolymerized by known methods. The frame, which is typically aluminium, can be easily melted and recast into new products. The glass panel can be recycled according to the method described below, or alternatively through other known methods, while a high shear homogenizer and centrifugation or similar gravimetric methods can reduce the encapsulated solar cell to EVA gel and photo-voltaic fragments, the metals of which can be separated, for example by electrowinning. Another embodiment of the method is shown in FIGURE 3. In this embodiment, the back sheet is not removed, and instead the solar panel 1 (with the frame and junction box removed, and optionally having being cut and or shredded into smaller pieces) is contacted with the ionic liquid-organic solvent mixture 13 in step (1). This results in the dissolution of the outer or air-side PVF layer 12 from the solar panel 1 into the ionic liquid-organic solvent mixture 13. The mixture 13 can be cooled to solidify the PVF and separate it out for recovery. The remaining elements of the solar panel are then washed with water in step (2) and then contacted with a concentrated caustic aqueous solution in step (3) in order to depolymerize the PET into terephthalic acid. The following step (step (4)) is another wash with water, before the solar panel is contacted with the ionic liquid-organic solvent mixture 13 a second time (step (5)), to dissolve the cell-side PVF layer 10. The remaining elements of the solar panel, the encapsulated solar cell 6 and glass panel 4 are washed with water (step (6)) to remove the ionic liquid and then crushed and incinerated, before undergoing a vortex milling and a sieving process to separated glass fines 15 from photo-voltaic components 16. The photo-voltaic components can then be separated into their constituent elements (silver, copper, silicon, etc.) by acid leaching, electrowinning, or other known methods. The inventors have also developed a process for recycling the glass front panels, producing glass fines where at least half the glass fines have a particle size of less than 83 µm. Further, the inventors have found that the produced glass fines are suitable for use in building materials. Examples of building materials include as fine aggregates in concrete and asphalt, laying-course materials such as mortar for block paving, sands for bedding and backfill, and as an additive in unbound aggregates. Two preferred building materials are mortar and concrete. Mortar and concrete are both mixtures of sand and cements in different amounts. While the glass fines may potentially partially or totally replace either the sand or cement component, the inventors have found that the glass fines may be particularly useful as a sand replacement in these applications. To convert the glass panel into glass fines, the glass panel must be removed from the remainder of the solar panel. As previously mentioned, this process may take the form of removing the junction box and aluminium frame from the solar panel, and then cutting and/or shredding the remainder of the solar panel into smaller pieces. The EVA and fluoropolymer back sheets may be separated using the method detailed above, and the glass pieces can then be milled. Other components may be separated out through known methods such as optical or magnetic sorting either or both pre and post milling. The inventors have found that the most common milling methods, namely hammer and ball milling, are ill-suited to the production of glass fines from solar glass panels. In hammer milling, hammers contact the glass to break it into smaller pieces, while in ball milling, grinding balls contact the glass instead. These methods are ill-suited because they result in glass fines with particle sizes too large to be used in building materials, necessitating repeated milling of the glass fines in these machines. Conversely, the inventors have found that vortex milling, where the glass pieces are accelerated and contact each other, produce glass fines with a smaller particle size, which is better suited for use in building materials. Preferably, the vortex milling is specifically vortex oscillation milling, which has a comparatively higher output and less energy consumption compared to other vortex milling methods. In this process, a vortex is formed within a chamber into which coarse particles are fed. The particles accelerate in the vortex and impact each other due to the turbulence, breaking up the particles into finer and finer particles. The intensity of the created vortex oscillates, improving the efficiency of the process. This process also dehydrates and mixes the particles, which are also desirable when creating glass fines for use in building materials. The present disclosure will become better understood from the following experimental results. The present method involves contacting a substrate including at least one PVF film with an ionic liquid comprising an organic acid and a trialkyl amine. For example, the inventors have found that organic acids such as acetic acid (AcOH) and p-toulunesolphonic acid (PTSA), and organic bases such as trimethylamine (TEA) and tributylamine (TBA) are suitable to produce effective and low-cost ionic liquids for the present method. To test the effectiveness of saidmethod, the inventors prepared equimolar mixtures of [TEA]/[AcOH], [TBA]/[AcOH], and [TBA]/[PTSA], the chemical structures of which are shown below:

To confirm the species in these three experimental ionic liquids, FTIR spectrometry was carried out, the results of which can be seen in FIGURE 4 which shows spectra for [TBA]/[AcOH] 41, [TBA]/[PTSA] 42, and [TEA]/[AcOH] 43 respectively. The inventors have found that the addition of an organic solvent such as DMF, DMSO, or THF can assist in the dissolution of PVF in the ionic liquid, either when the substrate is contacted with the solvent prior to the ionic liquid, or when the substrate is contacted with a mixture of the ionic liquid and organic solvent. To assess the feasibility of these mixtures, the inventors mixed each of the three ionic liquids ([TEA]/[AcOH], [TBA]/[AcOH], and [TBA]/[PTSA]) with DMF in volumetric ratios of 1:1, 1:2, and 1:3 ionic liquid to DMF. Samples of a back-sheet obtained from an end-of-life solar panel were contacted with each of these mixtures at 70°C to assess the effectiveness of the method. The inventors found that faster dissolution of the PVF occurred at the 1:3 ionic liquid to DMF ratio compared to the 1:1 and 1:2 ratios. For example, the 1:3 [AcOH]/[TBA] to DMF mixture was able to dissolve the PVF at 70°C in 10 minutes, while the 1:1 and 1:2 ratio mixtures required 25 minutes. Similarly, the 1:3 [AcOH]/[TEA] to DMF mixture was able to dissolve the PVF film at 70°C in 15 minutes, while the other ratio mixtures required 40 minutes to dissolve the PVF. One advantage of the present method is that the PVF can be recovered upon cooling of the ionic liquid/organic solvent mixture. The PVF material solidifies and separates when the mixture is brought back to room temperature. After the PVF material is extracted or separated from the ionic solution-organic solvent mixture, the mixture can be reused with further substrates. FIGURES 5, 6, and 7 show SEM images of the extracted PVF following water and methanol washing. FIGURE 5 shows PVF extracted from [PTSA]/[TBA] ionic liquid and DMF mixtures at 1:1, 1:2 and 1:3 volumetric ratios for subfigure (A), (B), and (C) respectively, FIGURE 6 shows PVF extracted from [AcOH]/[TBA] ionic liquid and DMF mixtures at 1:1, 1:2 and 1:3 volumetric ratios for subfigure (A), (B), and (C) respectively, and FIGURE 7 shows PVF extracted from [AcOH]/[TEA] ionic liquid and DMF mixtures at 1:1, 1:2 and 1:3 volumetric ratios for subfigure (A), (B), and (C) respectively. It will be understood that in other embodiments, acetone or further suitable washes may be used. To assess the processability of the extracted PVF, experiments were carried out where PVF material obtained from the 1:2 volumetric ratio [PTSA]/[TBA] to DMF mixture was given an acetone wash. The SEM images in FIGURE 8 show that the PVF microspheres aggregated and fused, forming a mesoporous structure. This suggests that the PVF recovered can be processed for reuse. Subfigure (B) shows the same material mesoporous structure as in (A) at a higher magnification. FIGURE 9 shows TEM imagery of the same PVF material shown in FIGURE 8. Clear fringes can be seen, with a gap of approximately 8 nm. This suggests that the recovered PVF material remains chemically resistant and inert, and may be suitable for applications such as constructing solid electrolytes in batteries. Finally FTIR spectrometry was carried out on the extracted PVF film, the PVF film from the solar panel, and a pure PVF film from Sigma Aldritch. A comparison of the extracted PVF film and the solar panel film are shown in FIGURE 10. Comparing the extracted PVF film 102 to the solar panel PVF film 101, it can be seen that no residual ionic liquid is present. Both original and recovered PVF have the same spectral features indicating similar chemo-physical properties. These results are seen for both commercial virgin PVF film pre- and post-extraction from a substrate as well as PVF films obtained from solar panels. The PVF film from solar panels may differ from commercial virgin PVF film as it may be degraded, oxidized over the solar panel's lifespan, or some additives used in the formulation of the commercial PVF used in the back-sheet of the solar panel. [0100] It will be understood that, while the above experimental data relates to PVF containing back-sheets, the process may be tailored for other fluoropolymer containing back- sheets with only minor alterations. The same is true of back-sheets with differing configurations. While the exact steps in the process may differ in order to expose the fluoropolymer layers, the step of using an ionic liquid to remove said layers will fundamentally be the same, though parameters such as the heating temperature, ionic liquid to organic solvent ratio, and contacting time may vary. [0101] While in the foregoing examples, specific reference has been made to solar panels, it will be understood by a person skilled in the art that PVF layers on substrates may be found in a variety of industries and applications. Some non-limiting examples include the construction industry; where PVF is used in facades, wall coverings, ceilings and floors, the aerospace and transportation industries, where PVF films are used on window shades, ceiling panels, insulation and moisture barriers and bulkhead partitions; in the signage industry, where PVF films are used to provide UV and moisture protection, and the healthcare industry, where PVF coverings are used as they can be cleaned using harsh disinfecting chemicals such as bleach. In some or all of these applications, a person may desire to recycle or recover the PVF from a substrate (in this case, a wall panel, window covering, advertising sign or similar) using a method as described in the present application. [0102] The inventors have also carried out a number of experiments to assess the suitability of glass fines produced from solar panel waste for use in building materials. [0103] The use of the term building materials in this specification is intended to refer to cements, concretes, mortars, and similarly prepared materials, as well as any articles such as tiles, bricks, blocks, sleepers, beams, screeds, and the like which are made from said prepared materials. [0104] Conventionally produced building materials, such as concretes and mortars, are produced through a mixture of a cement, water, and aggregates such as sand and gravel. Mortar typically includes only fine aggregates, such as sand, whereas concrete typically includes both fine aggregates and coarse aggregates. Sand and gravel may also be used as a filler material in said building materials, to strengthen the building material and/or to reduce the overall cost. The inventors propose the use of glass fines produced from solar panel waste for use in building materials, where they may replace or supplement existing fine aggregate and/or filler materials. [0105] To assess the suitability of the prepared glass fines from photovoltaic glass for use as a fine aggregate in concrete mixes, the glass fine properties were assessed against Australian Standard AS2758.1:2014 – Concrete Aggregates. The bulk density of the glass fines was found to be 1.60 t/m³ and 1.72 t/m³, similar to the density of natural fine sands, the particle density was found to be 2.5 t/m³ on both a dry and SSD basis, and 2.51 t/m³ on an apparent basis, in line with normal-weight aggregates. The water absorption rate ranged from 0.1% to 0.5% which is low relative to natural sands. The chloride content was found to be 0.002% Cl and the sulfate content was found to be 0.02% SO3, well below the maximum allowable level. Organic matter, light particles, sugar, and clay/silt particles were not detected in the prepared glass fines, and also met the standard's requirements. Where the prepared glass fines do not satisfy the requirements of AS2758.1 are in the particle size distribution and the total alkali content. [0106] The particle size distribution was assessed using the AS1289.3.6.1 method, where the glass fines were passed through a series of sieves of decreasing sizes. Natural sands lack any significant amount of particles below 300 µm, while glass sands extend down to smaller sizes less than 75 µm. Glass fines also have higher proportions of particles between 600 µm and 300 µm relative to natural sands.19% of the glass fines pass through a 75 µm sieve, which exceeds the 10% set out for concrete applications in AS1141.12. The fine glass particles may, however, provide some benefits over natural sands in some applications. Due to the higher surface area, stronger bonding and adhesion may be achieved relative to natural sands, and the fines may improve packing density and reduce voids in the resultant building material. The finer particle sizes may, however, reduce the workability of the slurry due to higher cohesion of the glass fines relative to natural sands. [0107] The total alkali content of glass fines as measured by XRF is higher than natural sands, exceeding the standard maximum of 2.8 kg/m³ for concrete. The reason for limiting the amount of alkali in concretes is to limit the risk of alkali-silica reactions in concrete. XRF data only indicates the overall bulk chemistry of the glass fines, rather than the alkali availability which can cause alkali-silica reactions. ASR testing, which provides a measure of the reactive alkali in the glass fines by analysing mortar bar expansion, showed similar ASR performance for concrete with glass fines in place of natural sands. This indicates that despite the higher total alkali content, the risk of alkali-silica reactions is comparable to natural sands and the glass fines are still suitable for use in building materials. [0108] Experiments were carried out on two separate batches of photovoltaic glass to produce glass fines for use in building materials. The photovoltaic glass, in the form of crushed glass and solar panel back-sheet cuts, was sieved to separate out the glass from other components and vortex mill. Particle size, crystallinity, microstructural, and elemental analysis was performed on the two batches of glass waste to determine the variability of the feed material. The results show that there is considerable variation between different batches of vortexed solar panel glass. [0109] The particle size of the two batches was investigated using a laser particle size analyser to obtain the specific surface area for both batches, as well as the D10, D50 and D90 values, which represent that 10%, 50% and 90% of the particles in each batch are smaller than these values, respectively. These results are tabulated below:

[0110] Batch 2 has a finer particle size, with at least 50% of the glass particles finer than 82.9 µm (as represented by the D50 value), and a specific surface area almost 50% more than Batch 1. [0111] The two batches of solar panel waste glass were also characterised using Scanning Electron Microscope Energy Dispersive X-ray (SEM-EDX). The results are shown in FIGURE 11A-11D. FIGURE 11A shows SEM imagery of Batch 1 at 100x magnification, while FIGURE 11B shows SEM imagery of Batch 2 at the same magnification. In line with the results from the particle size distribution analysis, the particles of Batch 2 in FIGURE 11B are comparatively finer than those of Batch 1 in FIGURE 11A. FIGURE 11C and 11D show the elemental map of Batch 1 and Batch 2 respectively. Both batches show calcium and silicon, which is expected as they are basic components of soda-lime glasses. The presence of iron was also detected, which is attributed to the soldering material used in solar panels. It is noted that approximately five times the amount of iron is present in Batch 1, this may represent a larger proportion of soldering material being present in the initial feed material of Batch 1 compared to Batch 2. Aluminium present in both batches is thought to be remnants of the aluminium frame. Titanium detected in Batch 1 is thought to be from titanium dioxide coatings commonly used as an anti-reflective coating for solar panels. Given that Batch 2 did not show detectable titanium, the solar panel from which Batch 2 is sourced most likely did not include such a coating. This highlights that the composition of glass fines is dependent on the specific type of solar panel glass used. This may need to be taken into account when using the glass fines in building materials, as the presence of these elements may cause disadvantageous effects on the resultant material and may need to be separated from the glass prior to their use as a component in said materials. The elemental composition of both batches are tabulated below:

[0112] The crystalline phases for each batch were assessed by X-Ray Diffraction (XRD). The results can be seen in FIGURE 12. The spectra of both Batch 1 (121) and Batch 2 (122) show humps between 20 and 30 degrees, which is attributed to the amorphous soda-lime glass. The crystalline phases, however, differ significantly from each other. In Batch 1, the main peaks are attributed to titanium oxide and iron oxide, which aligns with the elemental analysis carried out on the batches and is attributed to soldering from the solar cell, as well as contaminants from other waste streams. In Batch 2, the main peaks are associated with calcium/magnesium carbonate and a series of yttrium, gadolinium, ytterbium, indium oxides and fluorides, which are coating materials commonly used in solar panels to improve efficiency. This also suggests that Batch 2 was sourced from a different solar panel to Batch 1. [0113] The alkali content of the two batches of solar panel glass fines was also assessed, as it is important not to exceed acceptable limits for concrete in order to use the glass fines as a sand replacement. X-Ray Fluorescence (XRF) spectrometry was used to obtain the following oxide weights of each batch:

[0114] The alkali equivalent Na₂Oeq can be calculated by the following equation: ^^ ^^₂ ^^ ^^ ^^(%) = ^^ ^^₂ ^^(%) + 0.658 × ^^₂ ^^ (%) [0115] This gives the following values:

[0116] The equivalent alkali contribution can then be obtained using the following formula:

100 [0117] This provides an equivalent alkali contribution of 0.015 kg/m³, which falls well below the 2.8 kg/m³ maximum of AS2758.1. [0118] The two batches were used to create a number of example concrete mixes, where the photovoltaic glass fines were used as a partial substitute for sand in different ratios:

[0119] The workability of each mixture was assessed using a slump test with a target slump of 80 mm. In each mix, the amount of water reducer was adjusted to ensure this target slump was obtained. The higher dosage of water reducer required for mixes using PV glass from Batch 2 is attributed to the greater specific surface area of the finer particle sized PV glass fines in Batch 2 relative to Batch 1. [0120] These mixes were then assessed for their compressive strength over 3, 7 and 28 day periods using a compression testing machine. Samples in the form of cylinders with dimensions of 200 mm height and 100 mm diameter were fabricated using each mix, and the loading speed for the machine was fixed at 0.5 MPa/s. [0121] The results are shown in FIGURE 13 which shows the compressive strength for the control concrete mix (131), concrete with 20% glass substitution from Batch 2 (132), concrete with 50% glass substitution from Batch 2 (133), concrete with 80% glass substitution from Batch 2 (134), concrete with 50% glass substitution from Batch 1 (135), and concrete with 80% glass substitution from Batch 1 (136). Replacing normal sands with the Batch 2 of PV glass decreases the compressive strength of the concrete samples. The mix containing 20% PV glass from Batch 2 possesses relatively high compressive strength, achieving 35 MPa at the age of 28 days and satisfying the requirement of Grade N32 concrete. The mixes of with 50% and 80% substitution show relatively low strength compared to the other mixes but are still able to meet the requirement of the Grade N25 concrete. Interestingly, the concrete samples using Batch 1 of the PV glass exhibit comparable compressive strength to the reference samples. The samples with 80% PV glass achieve 40.7 MPa at 28 days, even higher compressive strength than the samples with 50% replacement. This may indicate some degree of interaction between the additional elements present in Batch 1 with the other components of concrete. [0122] With the concrete mixes meeting the compressive strength requirement of Grade N25 concrete, further tests were carried out to assess the feasibility of using PV glass fines as a sand replacement for concrete. [0123] Tests were carried out on the concrete mix with 50% glass substitution from Batch 1 and the control mix to compare the water absorption of concrete with solar panel glass waste used as a sand replacement. The test was carried out according to AS 1012.21 (1999). Four samples each were produced by cutting a 100 mm by 200 mm cylinder of the control and test mix into four 100 mm by 50 mm disks. Each disk was dried in an oven for 24 hours and the dry weight measured. Each disk was then submerged in water for 48 hours to determine the saturated surface dry (SSD) weight. The disks were also submerged in water at 100°C for six hours and the SSD weight measured. These were used to obtain the percentage of water absorption for both immersed and boiled water (100°C) The results are tabulated below:

[0124] While the test mix has a greater water absorption compared to the control, it still falls within the limit of 6% for acceptable concrete permeability. This also indicates an evenly distributed concrete sample with minimum pores and limited unreacted materials in the mix. [0125] The ability of the produced concrete to resist salt attack was also investigated. Samples of concrete fabricated with 20% and 50% glass substitution from Batch 1, as well as a control mix, were prepared in the form of 50 mm by 25 mm by 20 mm pieces. These pieces were dried in an oven and then immersed in NaCl solution. This was repeated over 11 cycles, with each sample's weight and dimensions measured both after a water bath and drying oven. The average change in the mass and dimensions for each mix after 11 cycles are tabulated below:

[0126] These results show that there are insignificant changes in the dimensions of the samples, with the change within the range of human error. It is noted, however that a larger percentage mix of solar panel waste glass results in a greater increase in overall weight after the salt bath. [0127] The shrinkage of the produced concrete mixes was also investigated. Samples of concrete fabricated with 20% and 50% glass substitution from Batch 1, as well as the control mix were tested according to AS 1012.13. Concrete beams with the dimensions 75 mm by 75 mm by 285 mm were cast, demoulded, and placed in a curing tank. Length change measurements were recorded at one-week intervals, from which microstrain measurements can be obtained according to AS 1012.13. The specimens were kept in a controlled environment chamber at 23±1°C and 50% relative humidity over the course of the experiment. The results of this experiment are tabulated below:

[0128] All concrete samples contracted after being placed in the carbonation chamber. This is assumed to be due to loss in water. No cracking was observed in any of the samples. [0129] The inventors also investigated the suitability of solar panel glass fines as a sand replacement for mortar. Mortar mixes were made with solar panel glass fines replacing 20%, 50% and 80% of the sand in the mortar. The mixes are tabulated below:

[0130] In a similar manner to the concrete mixes, the inventors found that a greater proportion of water reducer relative to the control mix was required with increasing glass substitution, which is attributed to the larger surface area of the glass particles within the mixture. A slump test was performed on the produced mortar, the results of which are tabulated below:

[0131] These results show that, with the addition of water reducer, a comparable or only slightly greater slump than the control mix can be achieved. [0132] The density and compressive strength of these produced mortars were also analysed. The cured density of the mixes with glass substitution were found to have a lower relative density relative to the control mortar, as tabulated below:

[0133] Cured samples of each mix were also subjected to compressive strength testing at 3, 7, and 28 days. The results are tabulated below:

[0134] The early strength of mortar with solar panel glass fines substituting sand appears to decrease as the proportion of glass fines increases. The 28-day compressive strength of the samples, however, is comparable or exceeds the strength of the control mix. These results suggest that 20% sand replacement using solar panel glass fines provides optimal strength for both early age and 28-day strength. An increase to the proportion of glass fines in the mortar shows deceases in early strength, with 50% substitution and 80% substitution having 3-day strength reductions of 7.9% and 9.0%, respectively, when compared to the control. [0135] The 7-day strengths were also lower than the control for both 50% and 80% glass substitution, however, this difference was less significant at only 1.9% and 4.4%, respectively. The 80% glass substitution mortar resulted in a 28-day compressive strength that was comparable to the control sample demonstrating the potential utility for high proportions of PVG to replace sand in applications where early strength is not an essential criterion. [0136] A potential explanation for the delayed strength development in the mix designs with higher glass fine content is the pozzolanic effect, which is the chemical reaction between reactive silica or alumina in the presence of water during the hydration process. Furthermore, the significant effect of pozzolanic activity using glass fines is also very probable due to approximately 12% of the PVG particles less than 20μm in size. It has been found that particle sizes of less than 20μm promote pozzolanic activity. There is a non-trivial amount of glass material of this size in both the 50% and 80% glass substitution mortars explaining their development of late-stage strength. [0137] These results suggest that building materials may be created using glass fines obtained from solar panel waste glass. [0138] The inventors also investigated the effect of adding a surface modifying agent to improve the binding between the glass and cement matrix. In this experiment, the specific surface modifying agent was GlassM8™ obtained from Select Building Supplies.0.5 g of this agent was hydrolysed in 55 g of distilled water with 0.15 g sodium hydroxide for 30 minutes. A 550 g sample of solar panel waste glass (from Batch 2) was mixed with the surface modifying agent for 5 minutes before being enclosed in a container for 2 hours at 20°C and then dried in an oven at 105°C for 24 hours. [0139] SEM images of the solar glass panel glass particles before and after treatment with the surface modifying agent are shown in FIGURE 14A and 14B respectively. These images show that the treated glass particles appear comparatively rougher than the untreated glass, which is attributed to the attachment of molecules of the surface modifying agent onto the glass surface. [0140] Treated and untreated glass fines were used to create two mortar mixes, both at 50% glass substitution for sand. The compressive strength of the produced mortars at 3, 7 and 28 days is shown in FIGURE 15, with the control mix (151), a mix with 50% sand substitution with untreated glass fines (152) and a mix with 50% sand substitution with glass fines treated with the surface modifying agent (153) represented. These results indicate that the modified surface glass fines lead to higher compressive strength compared with raw glass fines. This suggests that the surface modifying agent is able to improve the performance of solar panel glass waste in concrete mixes. [0141] In the foregoing description of certain embodiments, specific terminology has been resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. [0142] In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear. [0143] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. [0144] In addition, the foregoing describes only some embodiments of the invention(s), and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive. [0145] Furthermore, invention(s) have described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Claims

The claims defining the invention are as follows: 1. A method for separating fluoropolymer layers from a substrate, the method comprising: contacting the substrate with an ionic liquid comprising an organic acid and an organic base to dissolve at least one layer of the fluoropolymer from the substrate.

2. The method of claim 1, further comprising: contacting the substrate with an organic solvent prior to contacting the substrate with an ionic liquid.

3. The method of claim 1, wherein the substrate is contacted with a mixture comprising the ionic liquid and an organic solvent.

4. The method of claim 3, wherein the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:100.

5. The method of claim 4, wherein the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:10.

6. The method of claim 4, wherein the ratio of ionic liquid to organic solvent in the mixture is between 1:1 and 1:3.

7. The method of any one of claims 2 to 6, wherein the organic solvent is chosen from dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or tetrahydrofuran (THF).

8. The method of any one of the preceding claims, wherein the organic acid in the ionic liquid is chosen from acetic acid (AcOH) or toluenesulfonic acid (PTSA).

9. The method of any one of the preceding claims, wherein the organic base is chosen from triethylamine (TEA) or tributylamine (TBA).

10. The method of any one of the preceding claims, wherein contacting the substrate with an ionic liquid is carried out at between approximately 20°C and 120°C.

11. The method of claim 10, wherein contacting the substrate with an ionic liquid is carried out at between approximately 50°C and 90°C.

12. The method of claim 11, wherein contacting the substrate with an ionic liquid is carried out at between approximately 60°C and 70°C.

13. The method of any one of the preceding claims, wherein contacting the substrate with an ionic liquid is carried out for between 5 and 40 minutes.

14. The method of claim 13, wherein contacting the substrate with an ionic liquid is carried out for between 5 and 25 minutes.

15. The method of claim 14, wherein contacting the substrate with an ionic liquid is carried out for between 5 and 10 minutes.

16. The method of any one of the preceding claims, further comprising: cooling the ionic liquid or mixture to form solid fluoropolymer material.

17. The method of claim 16, wherein the fluoropolymer separated from the cooled ionic liquid or mixture is washed with water, methanol, and/or acetone following separation.

18. The method of any one of the preceding claims, where the fluoropolymer is PVF or PVDF.

19. The method of any one of the preceding claims, wherein the substrate is a back-sheet for a solar panel.

20. The method of claim 19, wherein the back-sheet includes an outer layer of a fluoropolymer on one side of a polyester film and an inner layer of a fluoropolymer on an opposing side of the polyester film; and wherein contacting the back-sheet with an ionic liquid dissolves the outer layer of the fluoropolymer; the method further comprising: washing the back-sheet; depolymerising the polyester film of the back-sheet; and contacting the back-sheet with the ionic liquid a second time to dissolve the inner layer of the fluoropolymer.

21. A method of recycling glass from a photovoltaic cell, comprising: separating glass components from the photovoltaic cell; and milling the glass components to produce glass fines.

22. The method of claim 21 wherein the milling is in the form of vortex milling.

23. The method of claim 22, wherein the vortex milling is in the form of vortex oscillation milling.

24. The method of any of claims 21 to 23, wherein the method further comprises: filtering out at least one of the following elements from the glass fines: Fe, Ti, Zn, Co, Pb, Cd, Cu, Ag, Yt, Gd, Yb, and/or In.

25. The method of any one of claims 21 to 24, further comprising adding a surface modifying agent to the glass fines.

26. The method of any one of claims 21 to 25, wherein the glass fines are used as a replacement for a filler material or fine aggregate in a building material.

27. A method of producing a building material from photovoltaic glass, comprising: milling the photovoltaic glass to produce glass fines; and combining the glass fines with at least a cement and water to form a building material.

28. The method of claim 27, wherein the glass fines are used as a filler material in the building material.

29. The method of claim 28, wherein the glass fines comprise approximately between 20 and 80 wt% of the total filler in the building material.

30. The method of claim 29, wherein the glass fines comprise approximately between 20 and 50 wt% of the total filler in the building material.

31. The method of any one of claims 27 to 30, wherein the building material is a concrete or a mortar.

32. The method of claim 31, wherein the glass fines are used as a sand replacement in the concrete or mortar.

33. The method of any one of claims 27 to 32, wherein the glass fines are combined with a water reducer.

34. The method of claim 33, wherein the water reducer is added in an amount between approximately 1.4 and 3 kg/m³.

35. A building material including glass fines produced from milled photovoltaic glass as a filler or fine aggregate replacement.

36. The building material of claim 35, made using the method of any one of claims 27 to 34.

37. A method for separating a solar panel into recyclable components, the solar panel comprising: a frame and junction box; a glass panel; a solar cell sandwiched between layers of ethylene vinyl acetate (EVA); and a back-sheet comprising a layer of polyvinyl fluoride (PVF) or polyvinylidene fluoride (PVDF) and a polyester film; wherein the method comprises: contacting the back-sheet with an ionic liquid comprising an organic acid and a trialkyl amine to dissolve at least one layer of PVF or PVDF from the back-sheet.

38. The method of claim 37, wherein contacting the back-sheet with an ionic liquid is carried out according to the method of any one of claims 1 to 20.

39. The method of either claim 37 or 38, further comprising: separating the glass panel from the solar panel; and milling the glass components to produce glass fines.

40. The method of claim 39, wherein the glass fines are used to produce a building material according to any one of claims 27 to 35.

41. The method of any one of claims 37 to 40, further comprising: mechanically separating the frame and junction box from the solar panel prior to any other steps.

42. The method of any one of claims 37 to 41, further comprising: incinerating the solar cell and EVA layers; sieving the incinerated solar cell to separate glass from photo-voltaic fragments.

43. The method of any one of claims 37 to 42, further comprising: using high shear homogenizers and/or centrifugation to separate the solar cell and EVA layers into EVA gel and photo-voltaic fragments.

44. The method of any one of claims 37 to 43, further comprising: separating the photo-voltaic fragments into separate metal components and silicon components by electrowinning.