Novel polymer-based electrodes

Abstract

The present invention discloses an electrochemical probe (or sensor) that can be used to detect compounds present in water and is resistant to corrosive agents present in seawater or industrial water, wherein the probe comprises at least one polymer matrix electrode, wherein the electrode is selected from the group consisting of a counter electrode, a reference electrode and a working electrode.

Description

Field of the Invention

[0001] The present invention relates to a novel electrochemical probe (or sensor) that can be used to detect compounds present in water and is resistant to corrosive agents present in seawater or industrial water, wherein the probe comprises at least one polymer matrix electrode, wherein the electrode is selected from the group consisting of a counter electrode, a reference electrode and a working electrode.

[0002] In other words, the present invention relates to the use of polymeric materials for the preparation of electrodes for electrochemical probes and to a method for their preparation, wherein said electrodes are inexpensive, versatile and resistant to corrosive agents present in seawater or water of industrial origin.

[0003] According to one embodiment, the present invention relates to a conventional electrochemical probe known in the art, wherein at least one electrode is a polymer matrix electrode. Background of the Invention

[0005] The specific conductivity of a conductor defines its conductivity "σ". Instruments used to measure conductivity are called "conductometers". Its unit of measurement is "Siemens / meter" (S / m), according to the international system.

[0006] Electrochemical probes belong to the field of amperometric sensors, which are used to measure the concentration of chemical reagents present in, for example, seawater, swimming pool or industrial water or to measure other water parameters.

[0007] The term "amperometry" refers to a specific voltammetric technique in which the current is measured at a fixed potential chosen to obtain the discharge of electroactive species at the working electrode surface.

[0008] The curve obtained is a curve of current versus time, and the correlation between current and analyte concentration is determined by the Cottrell equation and is well known to those skilled in the art.

[0009] In amperometry, the typical instrument used comprises a counter electrode, a reference electrode (where the potential must be known and constant over time and independent of the composition of the solution containing the analyte in which the reference electrode is immersed), a working electrode (whose response depends on the concentration of the analyte) and finally a device that can be used to apply the potential and record the current generated by the target species during the oxidation or reduction reaction on the working electrode surface.

[0010] Corrosion is the physicochemical interaction between a metal and its environment which leads to changes in the properties of the metal and can impair the functionality of the metal or of technical equipment containing it (see ISO 8044:2010).

[0011] The adverse consequences of corrosion can range from external defects to complete failure of technical systems, causing considerable economic losses and even danger to personnel.

[0012] For metals commonly used in engineering such as carbon steel, stainless steel, zinc, copper and aluminum, the typical corrosion process can be considered as the reverse process of the thermodynamically favorable reaction of the metal extraction process.

[0013] Like all chemical reactions, the corrosion process occurs when environmental conditions are favorable.

[0014] Different types of corrosion can occur:

[0015] -Corrosion due to chemical reactions: it occurs at high temperatures, when the metal reacts with hot gases and forms an oxide layer;

[0016] - Corrosion by physical reactions of metals: due to the diffusion of hydrogen into the metal, said corrosion causes embrittlement and may lead to component failure;

[0017] - Electrochemical corrosion: It involves the electrical exchange of electrons in the metal and ions in a conductive electrolyte such as a film of water on the metal surface;

[0018] -Uniform corrosion or surface corrosion: It is a form of corrosion in which the surface is removed almost uniformly.

[0019] Corrosion rates are usually expressed in micrometers per year (μm / y).

[0020] Using the average value, the expected life of the component can be calculated, which can be improved by increasing its thickness.

[0021] For example, uniform corrosion can occur in carbon steel and galvanized steel under exposed conditions (https: / / www.hilti.it / content / dam / documents / pdf / e4 / engineering / manuals / Hilti_Corrosion-Handbook_W4412_it.pdf).

[0022] Polymer materials, also known as plastic materials or synthetic resins, are substances formed from very large organic molecules (ie macromolecules) derived from the association of small units called monomers through chemical bonds.

[0023] These units can be units of one or more substances. Some polymers, such as cellulose, natural rubber, and resins, are of natural origin; most polymers known to date are of artificial origin. The first industrial polymers (celluloid and Bakelite) were produced in 1870 and 1907, respectively.

[0024] Polymer materials are characterized by low specific gravity, considerable chemical inertness and, in many cases, low yield strength and high elongation at break. They also have low resistance to high temperatures, which limits their application.

[0025] When considering their structure, polymeric materials are divided into: linear polymers, where monomer units are combined to form long, more or less entangled chains; branched polymers, where side branches extend from the main chain; and cross-linked polymers, where some branches chemically link further chains.

[0026] Polymers can also be classified as thermoplastics and thermosets based on how they behave when the temperature changes.

[0027] Thermoplastic polymers are polymers formed from linear chains that soften when heated and return to their solid consistency at lower temperatures, in a cycle that can be repeated countless times.

[0028] For example, polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyacrylonitrile butadiene styrene (ABS), polyacrylonitrile (PAN), polyethylene terephthalate (PET), polyamide (PA), polycarbonate (PC), polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE) belong to this group.

[0029] Thermosetting polymers are polymers formed from large cross-linked molecules that, when heated, first soften and then eventually solidify and no longer flow.

[0030] For example, saturated and unsaturated polyesters, epoxy resins, urea / formaldehyde, melamine / formaldehyde and phenolic polymers belong to this group.

[0031] The polymer resin includes polyacrylic resin; polyvinyl resin; fluorinated resin; polyamide; acetal; polyacetal; polyoxymethylene acetal; polyphenylene ether; cellulose; polyester; epoxy resin; polyurethane; amine; polyvinylidene fluoride or polyvinylidene fluoride.

[0032] Silicone materials are non-conductive polymers (see http: / / corsiadistanza.polito.it / on- line / Materiali / pdf / dispensa materiali.pdf ).

[0033] Electrical conductors are materials that allow electric current to flow through them. The best-known metallic conductors are silver, including silver nanowires; copper; gold; aluminum; zinc; chromium; tin; iridium; tungsten; nickel; iron; platinum; and lead.

[0034] The best-known non-metallic electrical conductors are carbon and its derivatives, such as graphene or carbon nanotubes. Ceramic conductors, such as indium tin oxide (ITO) or aluminum zinc oxide (AZO), are also conductive materials.

[0035] In recent years, many efforts have been made in the research field to find viable alternatives to the metals traditionally used in many types of electrical products and components.

[0036] The need to replace metals with alternative materials is due to their heavy weight, to their often expensive and limited available production processes, and sometimes also to corrosion problems which often require recourse to expensive and polluting protective surface coatings.

[0037] Often, the reason a component is made of metal has nothing to do with its mechanical properties, but rather with its high thermal and electrical conductivity.

[0038] Polymers that were generally known as insulating materials and therefore previously abandoned have now become interesting starting materials for the industrial preparation or discovery of conductive or non-conductive polymers or polymer resins on the market, since they can be rich in metallic or non-metallic electrical conductors (http: / / www.matech.it / downloads / websiteMat / news / 417 / Conducibilit%C3%A0.pdf).

[0039] To date, there are a number of devices on the market suitable for measuring the concentration of some analyte or other parameters in seawater, pond or industrial water samples, for example by using colorimetric or electrochemical detection.

[0040] Platinum, gold and glassy carbon electrodes are described in Analytica Chimica Acta (2005), 537: 293- 298. These types of electrodes have the disadvantage of undergoing a passivation process of the electrode surface in the presence of high concentrations of free chlorine.

[0041] Numerous probes and / or electrodes for measuring pH or electrolytes dissolved in water are described at https: / / www.prominent.it / it / Prodotti / Prodotti / Sistemi-di-misura-e-regolazione-sensori / Sensori / p-sensors-free-chlorine.html.

[0042] A conductive polymer material reinforced with carbon fibers (Tecapeek ELS CF30, ).

[0043] A conductive polymer material reinforced with carbon nanotubes (Tecapeek ELS nano) is described in https: / / www.ensingerplastics.com / it-it / semilavorati / prodotti-semilavorati / peek-tecapeek-els-nano-black. ).

[0044] There are many companies on the market that provide electrochemical sensors or electrochemical probes for pH measurement of the concentration of compounds dissolved in water, but none of them provide electrochemical sensors or electrochemical probes that include auxiliary electrodes, reference electrodes, and / or working electrodes made of one or more conductive polymer materials.

[0045] As mentioned above, commercially available electrochemical probes contain counter, reference, and working electrodes made of conductive metals such as steel, gold, silver, platinum, and nickel. The best commercially available free chlorine probe has a steel counter electrode, a silver reference electrode, and a gold working electrode (sonda per Cloro libero, organico ed inorganico Tecnosens, modello NCL T20 eNCL T2 http: / / www.tsens.eu).

[0046] Steel electrodes oxidize easily and must be replaced frequently, otherwise the measured values will be altered.

[0047] This means high maintenance costs for the probes or (very often) replacing the entire damaged electrochemical probe with a new probe which contains, in addition to a new steel electrode, a new silver reference electrode and a new gold working electrode.

[0048] Typically, the working and reference electrodes are immersed in an electrolyte solution that protects them and allows them to function. These electrodes are in contact with the water to be analyzed through a membrane and therefore do not oxidize / degrade in a short time, but have very high production costs.

[0049] The production costs are related to the cost of the raw materials used (gold or silver) and the costs of the processes used to prepare the electrodes made of the precious metal.

[0050] In fact, for obvious reasons, the processing of gold and silver must take place in a controlled environment where it is possible to recover all scrap materials of high commercial value.

[0051] It is well known to those skilled in the art that the cost of managing electronic / sensor systems in a "water control" environment has a considerable cost.

[0052] It is also obvious to experts in the field that obtaining:

[0053] - A new counter electrode that does not have the above-mentioned disadvantages of steel electrodes;

[0054] - New reference and working electrodes made from materials much cheaper than silver or gold; and / or

[0055] - A new, simpler and therefore cheaper method for preparing these three electrodes

[0056] There is a noted need in the art.

[0057] Description of the Invention

[0058] The present invention relates to novel electrochemical sensors and electrochemical probes which can be used to determine compounds dissolved in water, which are significantly more resistant to corrosive agents present in seawater or industrial water and are significantly less expensive both in terms of the materials from which they are made and in terms of the methods for their preparation.

[0059] The probe comprises at least one auxiliary electrode (hereinafter also referred to as a counter electrode) and / or at least one reference electrode and / or at least one working electrode; wherein the electrode is obtained (manufactured) using a polymer matrix, and the polymer matrix comprises at least one conductive polymer, or at least one non-conductive or weakly conductive polymer combined / integrated with at least one conductive metal or non-metal material.

[0060] According to the present invention, the terms:

[0061] - "electrochemical sensor" (or electrochemical probe) means a sensor (or probe) comprising at least one auxiliary electrode and / or at least one reference electrode and / or at least one working electrode;

[0062] - electrochemical sensor or electrochemical probe does not refer to an electrochemical sensor, electrode or probe printed on paper or a polymer "surface / support";

[0063] - Conductive polymers are polymers that can provide enough electricity to "operate" the counter electrode, reference electrode or working electrode (good conductive polymers);

[0064] - A "non-conductive or weakly conductive" polymer is one that is not suitable for providing sufficient charge to "operate" a counter, reference or working electrode (it must be appropriately integrated / combined with a conductive metal or non-metal material before use);

[0065] - "conductive metal or non-metal" material refers to an electrical conductor (metal and / or non-metal) selected from the following group as non-limiting examples: carbon; carbon nanotubes; carbon nanohorns; carbon black; graphite, graphene, carbon fullerenes; silver; copper; gold; aluminum; zinc; chromium; tin; iridium; tungsten; nickel; iron; platinum; lead; indium tin oxide; aluminum tin oxide.

[0066] According to the present invention, the term "polymer matrix" refers to:

[0067] at least one conductive polymer, at least one conductive resin, or a mixture thereof;

[0068] at least one non-conductive or weakly conductive polymer mixed with at least one conductive polymer;

[0069] at least one non-conductive or weakly conductive resin mixed with at least one conductive resin;

[0070] at least one non-conductive or weakly conductive polymer mixed with at least one conductive resin;

[0071] at least one non-conductive or weakly conductive resin mixed with at least one conductive polymer;

[0072] at least one non-conductive or weakly conductive polymer in combination with at least one conductive metal or non-metal material;

[0073] at least one non-conductive or weakly conductive resin in combination with at least one conductive metal or non-metal material;

[0074] a mixture of at least one non-conductive or weakly conductive polymer and at least one non-conductive or weakly conductive resin in combination with at least one conductive metal or non-metal material; or

[0075] "Suitable materials", that is, materials that are ready to be used to prepare the novel electrodes of the present invention.

[0076] According to the present invention, the term "suitable material", ie a material ready for use in producing the novel electrode according to the invention, means, for example, the material obtained at the end of the production process according to the invention described below.

[0077] One object of the present invention is therefore a method for preparing a "polymer matrix" electrode, comprising the following steps:

[0078] Step 1:

[0079] Provided is a "polymer" selected from the group consisting of ethyl acrylate polymers, acrylonitrile-butadiene or styrene-butadiene copolymers, cellulose, epoxy resins, ethylene acrylic acid copolymers, fluoropolymers, natural rubber, melamine formaldehyde or melamine resins, hydrogenated nitrile rubber, polyethylene oxide or PEG, poly(4-methyl-1-pentene), polybutene, polyacetal, polyacetylene, polyacrylic acid, polyacrylonitrile, polyamide 6, polyamide, polyaniline, polybenzimidazole, polybutadiene, polybutylene terephthalate, polycarbonate, polychloroprene, polydimethylsiloxane (silicone), polyepichlorohydrin, saturated and unsaturated polyesters, polyetherketones, polyetherimides, polyethylene, low-density polyethylene, chlorosulfonated polyethylene, high density polyethylene, poly(3,4-ethylenedioxythiophene), polyethylene terephthalate, polyphenylene sulfide, polyphenylene oxide, polyphenylene sulfone, polyisoprene, polyisothianaphene, phenol / formaldehyde polymer, poly(methyl methacrylate), polyoxymethylene, poly(p-phenylene), poly(p-phenylene) sulfide, poly(p-phenylene)vinylene, polypyrrole, polypropylene, polystyrene, polytetrafluoroethylene, polythiophene, polyurethane or amino, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, ethylene propylene copolymer, urea-formaldehyde polymer, polyurethane polyester or polyurethane polyether, and any possible combination thereof, in liquid form;

[0080] - According to the present invention, "in liquid form" means that it is spontaneously in liquid form at room temperature; in case a polymer which is not in liquid form at room temperature is used, it must be dissolved / solubilized / liquefied by using a suitable solvent or by using heat, i.e. by bringing it to its melting temperature;

[0081] in:

[0082] If the polymer in liquid form is a conductive polymer, it will be used as is, i.e. without further integration (with conductive metal or non-metallic materials), and the method will continue directly with the third step;

[0083] If the polymer in liquid form is a non-conductive or weakly conductive polymer, it must be subjected to a second step.

[0084] Step 2:

[0085] adding at least one metal and / or non-metal conductive material to the non-conductive polymer of the first step, wherein the polymer is selected from the group consisting of carbon; carbon nanotubes; carbon nanohorns; carbon black; graphene; carbon fullerene; silver; copper; gold; aluminum; zinc; chromium; tin; iridium; tungsten; nickel; iron; platinum; lead; indium tin oxide (ITO); aluminum tin oxide (AZO); the addition amount is in the range of 0%-40%; the preferred addition amount is in the range of 0.01-35%; and the addition amount of 1-30% is particularly preferred;

[0086] in:

[0087] - carbon in the form of carbon fibers, carbon nanofibers, carbon nanotubes, carbon black or carbon nanoclay, carbon nanohorns;

[0088] - graphene in the form of graphene, graphene oxide, graphene nanosheets or fullerenes;

[0089] - the metal is in the form of a powder, dispersion, gel, granules, microparticles or nanoparticles and / or nanowires;

[0090] - conductive ceramics such as indium tin oxide (ITO) or aluminum tin oxide (AZO) in the form of powders, dispersions, gels, granules, microparticles or nanoparticles and / or nanowires;

[0091] It will be apparent to those skilled in the art that the dosage / amount of conductive material to be added to the polymer will depend on the conductive properties of the polymer material used and the degree of conductivity to be achieved. The degree of conductivity to be achieved will be readily determined by those skilled in the art; and

[0092] The combination / mixture / suspension thus obtained is kept under stirring for a period ranging from several minutes to several hours;

[0093] Step 3:

[0094] The liquid material from the first step or the second step, kept under stirring, is poured into a screw extruder, brought to the molding temperature, and molded into a suitable mold.

[0095] After cooling, the semi-finished product thus obtained is machined in order to obtain an electrode (thermoplastic polymer) of the desired shape and dimensions, ready for connection to an electronic measuring device.

[0096] Alternatively, the liquid mass of the first or second step, maintained under stirring, is poured into a mold and allowed to cool and optionally solidify.

[0097] The semi-finished product thus obtained is mechanically processed to obtain a product (thermosetting polymer) with the desired electrode shape and dimensions, ready for connection to electronic measuring devices.

[0098] The three-step preparation method described above can be described in different ways while maintaining all its essential features.

[0099] Therefore, another object of the present invention is a method for preparing a polymer matrix electrode, wherein:

[0100] - adding at least one metallic and / or non-metallic conductive material selected from the group mentioned above in the second step to the polymer selected from the group mentioned above in the first step in liquid form, in a dosage ranging from 0% to 40%; preferably in a dosage ranging from 0.01 to 35%; particularly preferably in a dosage of 1 to 30%; the mixture thus obtained is kept under stirring for a period of several minutes to several hours, then poured into a screw extruder, brought to molding temperature, and molded into a mold in the shape of an electrode;

[0101] or:

[0102] - pouring into a mold and allowing it to cool and optionally solidify;

[0103] After cooling, the semi-finished product thus obtained is machined in order to obtain an electrode having the desired shape and dimensions and ready for connection to an electronic measuring device.

[0104] According to the present invention, the term "curing" refers to a transformation following a cross-linking reaction (a process in which polymer chains undergo reactions at the level of reactive functional groups that produce bonds between different chains), which occurs between polymer chains with strong bond formation (covalent or ionic) (IUPAC, Compendium of Chemical Terminology, 2nd edition ("Gold Book"), compiled by A. D. McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997). XML online revision: http: / / goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https: / / doi.org / 10.1351 / goldbook).

[0105] In the first step, the second step, the third step, during the molding step or during the cooling and / or curing step in the mold, one or more industrially acceptable excipients, diluents, dyes, hardeners, rubbers, elasticizers, oils, metal salts and / or fluidizing agents and one or more heat treatments such as those described in "Composites manufacturing: materials, product, and process engineering" by Mazumdar, Sanjay K ISBN 0-8493-0585-3 2002 CRC-press can be optionally added.

[0106] Another object of the present invention is an electrode prepared using the polymer matrix obtained using the above method.

[0107] Another object of the present invention is an electrochemical sensor comprising at least one electrode prepared using the polymer matrix obtained by the above-described method, wherein said electrode is chosen from the group comprising: an auxiliary electrode, a reference electrode and a working electrode;

[0108] For the reference electrode, preference is given to using a polymer matrix comprising at least one silver-based conductive material.

[0109] Another object of the present invention is an electrochemical sensor comprising a data detection and transmission system, either battery- or battery-less, wherein the changes in the signal detected by said data detection and transmission system are transmitted via data transmission wires, or preferably via a wireless system using systems known in the art, such as, as a non-limiting example, a system using radio frequency identification (RFID) technology for transmitting data to an external reader using a small antenna that maximizes data collection and transmission efficiency.

[0110] The system is able to operate in "passive RFID" or battery-free mode, receiving the energy required for data transmission directly from the reading system, with a limited reading distance (up to 10-15m). In "active RFID" mode, if equipped with a battery, it allows data to be stored in the chip and achieve a longer transmission distance. (Amendola, S., & Marrocco, G. (2017). IEEE Transactions on Antennas and Propagation, 65(2), 473-481) (Caccami, MC, Hogan, MP, Alfredsson, M., Marrocco, G., & Batchelor, JC (2018). IEEE Transactions on Antennas and Propagation, 66(2), 609-617).

[0111] Another object of the present invention is an electrochemical probe comprising at least one electrochemical sensor as mentioned above.

[0112] Another object of the present invention is a polymeric material / compound selected from the group comprising: Tecapeek ELS CF30 Tecapeek ELS nano Tecaform AH ELS TecaflonPVDF ELS black; Tecapeek SD LARAMID K / 40 LARPEEK 10 LARPEEK 10 LARPEEK 10 LARTON LARTON LARTON K / 40 LARTON L LASTILAC RT LATAMID 66 H2 LATAMID66 H2 LATAMID 66 H2 LATAMID 66 H2 LATER 4 LATICONTHER 52 / 11 LATICONTHER 62 LATICONTHER 62 LATICONTHER 62 LATICONTHER 75 LATICONTHER80 LATICONTHER 87 / 28 LATIGRAY 82-03 LATIGRAY82-03 CW / 96 LATIGRAY 82-05 LATILUB 87 / 28-17ST LATIMASS 82-05 LATIOHM 57-05 PD01 LATIOHM 62-03 PD01 LATIOHM 66-04 PD01 LATIOHM 66-07 PD08 LATIOHM 73-09 PD01 LATIOHM 75 / 4-03 PD01 LATIOHM 75 / 4-08 PD01 LATIOHM 80-04 PD01 LATIOHM 80-05 CNT LATIOHM 82-02 LATIOHM 85-06 PD01 LATIOHM 87 / 26-06 LATIOHM87 / 28-05 PD01 LATIOHM 88 / 10-06 LATIOHM 90 / 13-09 PD01 LATISHIELD 36 / AR-08A LATISHIELD LATISHIELD LATISHIELD 38 / 11-08A LATISHIELD LATISHIELD 66-08A LATISHIELD LATISHIELD 66-10A LATISHIELD 66-10A H2 LATISHIELD 66-13A LATISHIELD LATISHIELD LATISHIELD 85-08A LATISHIELD LATISHIELD 87 / 28-10A FLOORS FLOORS FLOORS FLOORS FLOORS LATISTAT 52 / 7-02 LATISTAT 62-06 LATISTAT LATISTAT e LATISTAT It is used to prepare an electrode selected from the group consisting of a counter electrode, a reference electrode and a working electrode.

[0113] Another object of the present invention is a kit comprising at least one probe and at least one electrode according to the invention, at least one electronic control and / or actuation unit, at least one display (optionally a touch screen) and at least one measuring channel for storing the detected electrochemical parameters; and at least one data transmission system of the battery or battery-free type.

[0114] The possibility of manufacturing electrodes from conductive polymers allows for the thermal, electrical, and / or electrochemical properties of metal electrodes to be achieved, coupled with the simpler processing of polymers. This allows for the manufacture of electrodes with the desired geometry and material without falling within the technical limitations of conventional mechanical processing. This allows for the electrodes to be fabricated directly onto the support, reducing hydraulic sealing issues and the amount of precious metal required for this purpose.

[0115] Using smaller amounts of precious metals to fabricate electrodes can reduce costs; using the desired electrode geometry allows for improved probe performance.

[0116] A fundamental role in the measurement chain involves the electrical connection between the metal of the electrode and the wires used to transmit the signal to the measuring device. This connection is usually achieved by soldering, which involves indirectly connecting adjacent and heated components by melting a material with a lower melting point between them. This effectively acts as a "glue" between the two components.

[0117] Such a braze, besides being a very fragile point, can initiate undesirable electrochemical reactions if the braze comes into contact with liquid, thereby affecting the operation of the probe.

[0118] Due to the use of the polymer matrix of the present invention, it is now possible to integrate the electrical connections directly into the polymer material constituting the counter, reference and / or working electrodes, or to use the polymer itself as an adhesive between the electrodes and the wires connected to the instrument.

[0119] The following examples illustrate the present invention by referring to the above-mentioned drawings, but do not limit the present invention.

[0120] Description of the drawings

[0121] exist Figure 1 The electrochemical probe of the present invention is shown in FIG, wherein:

[0122] - Number 1 indicates the counter electrode made of "polymer matrix",

[0123] - Number 2 indicates the reference electrode made of a "polymer matrix",

[0124] - Number 3 indicates the working electrode made of a "polymer matrix", and

[0125] - Number 4 indicates the electrical connection area.

[0126] Figure 2 An example of a "polymer matrix" counter electrode is shown.

[0127] exist Figure 3 The three electrodes made of the "polymer matrix" of the present invention are shown in more detail in FIG.

[0128] - Number 1 indicates the counter electrode,

[0129] - number 2 indicates the reference electrode, and

[0130] - Number 3 indicates the working electrode.

[0131] Figure 4 Shown is the trend of the measurement system signal output over time, varying the free chlorine concentration in the analyzed water: 0.15, 0.30, 0.40, 0.80, 1.20, 1.90, 1.40, 5.0, 9.5, 13.0, 15.0, 18.0 ppm, relative to probes known in the prior art.

[0132] Figure 5 The trend of the signal output of the measuring system over time is shown, using a probe known in the prior art, wherein the counter electrode is prepared using the mixture of the present invention (PEEK modified with carbon nanotubes, see Example 19), and the reference electrode and working electrode are reference electrodes and working electrodes known in the art; the free chlorine concentration in the analyzed water is: 0.15, 0.30, 0.40, 0.80, 1.20, 1.90, 1.40, 5.0, 9.5, 13.0, 15.0, 18.0 ppm.

[0133] Figure 6 The trend of the signal output of the measuring system over time is shown, using a probe known in the prior art, wherein the counter electrode is prepared using the mixture of the present invention (carbon fiber filled PEEK, see Example 20), and the reference electrode and working electrode are reference electrodes and working electrodes known in the art; the free chlorine concentration in the analyzed water is: 0.15, 0.30, 0.40, 0.80, 1.20, 1.90, 1.40, 5.0, 9.5, 13.0, 15.0, 18.0 ppm.

[0134] Detailed description of the invention Example

[0135] Example 1 - Method for preparing an electrode by using polyvinylidene fluoride (PVDF) (thermoplastic) in combination with carbon black

[0136] 610 mg of CB were dispersed in 60 ml of DMF (N,N-dimethylformamide), and the resulting suspension was sonicated (30% amplitude, 200 W power) in an ice bath for at least 1 hour.

[0137] To the dispersion of sonicated CB was added 5 g of PVDF pellets.

[0138] The solution thus obtained was placed under gentle stirring at 90° C. for 2 hours and then at 60° C. until the solvent evaporated.

[0139] The solid thus obtained was collected and cut into pellet form.

[0140] The pellets were placed into a screw extruder and brought to a molding temperature of about 175°C to be molded into the desired shape.

[0141] The semi-finished product thus obtained is mechanically refined to obtain electrodes of the desired shape and dimensions, ready for connection to electronic measuring devices.

[0142] Example 2 - Method for preparing an electrode using polyvinylidene fluoride (PVDF) combined with carbon nanotubes

[0143] Following the method described in Example 1, using 122 mg of carbon nanotubes, electrodes of the desired shape and size were obtained, ready for connection to an electronic measuring device.

[0144] Example 3 - Method for preparing an electrode based on PET (polyethylene terephthalate, thermoplastic) combined with carbon nanotubes

[0145] Following the procedure of Example 2, but using PET (polyethylene terephthalate) instead of PVDF, electrodes of the desired shape and size are obtained, ready for connection to electronic measuring equipment.

[0146] Example 4 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanofibers

[0147] 498 mg of carbon nanofibers were dispersed in 50 ml of diethylene glycol butyl ether (BGE) and ultrasonicated in an ice bath for one hour (amplitude 30%, power 200 W). 10 g of epoxy resin (DGEBA Araldite ).

[0148] The mixture thus obtained was kept under stirring at room temperature until the BGE solvent was completely evaporated.

[0149] 6 g of hardener (Araldite triethyleneamine) and the mixture thus obtained is subjected to gentle mechanical stirring for 5 minutes and then poured into electrode-shaped molds.

[0150] After 24 hours at room temperature, the electrode is obtained in its final shape, ready for connection to an electrical measurement system.

[0151] Example 5 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanofibers

[0152] Following the method of Example 4, the BGE solvent was mechanically removed by filtering the dispersion of carbon nanofibers and BGE.

[0153] The carbon nanofibers disentangled by ultrasonic treatment were collected on filter paper and allowed to dry. After drying, the fibers were dispersed in the resin by mechanical stirring.

[0154] Example 6 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanofibers

[0155] According to the method of Example 5, the carbon nanofibers are dispersed in the hardener by mechanical stirring instead of being dispersed in the resin, and then added to the resin.

[0156] Example 7 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanotubes

[0157] The method of Example 4 was followed, except that the carbon nanofibers were replaced with an equal amount of carbon nanotubes.

[0158] Example 8 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanotubes

[0159] The method of Example 5 was followed, except that the carbon nanofibers were replaced with an equal amount of carbon nanotubes.

[0160] Example 9 - Method for preparing an electrode using epoxy resin (thermosetting) combined with carbon nanotubes

[0161] The method of Example 6 was followed, except that the carbon nanofibers were replaced with an equal amount of carbon nanotubes.

[0162] Example 10 - Method for preparing an electrode using epoxy resin (thermosetting) combined with silver nanopowder

[0163] The method of Example 4 was followed, except that the carbon nanofibers were replaced with an equal amount of silver nanopowder.

[0164] Example 11 - Method for preparing an electrode using epoxy resin (thermosetting) combined with silver nanopowder

[0165] The procedure of Example 5 was followed, except that the carbon nanofibers were replaced with an equal amount of silver nanopowder.

[0166] Example 12 - Method for preparing an electrode using epoxy resin (thermosetting) combined with silver nanopowder

[0167] The method of Example 6 was followed, except that the carbon nanofibers were replaced with an equal amount of silver nanopowder.

[0168] Example 13 - Method for preparing electrodes using epoxy resin (thermosetting) combined with gold nanoparticles

[0169] The method of Example 4 was followed, except that the carbon nanofibers were replaced with an equal amount of gold nanoparticles.

[0170] Example 14 - Method for preparing electrodes using epoxy resin (thermosetting) combined with gold nanoparticles

[0171] The method of Example 5 was followed, except that the carbon nanofibers were replaced with an equal amount of gold nanoparticles.

[0172] Example 15 - Method for preparing electrodes using epoxy resin (thermosetting) combined with gold nanoparticles

[0173] The method of Example 6 was followed, except that the carbon nanofibers were replaced with an equal amount of gold nanoparticles.

[0174] Example 16 - Method for preparing an electrode using epoxy resin (thermoset) combined with platinum nanoparticles

[0175] The method of Example 4 was followed, except that the carbon nanofibers were replaced with an equal amount of platinum nanoparticles.

[0176] Example 17 - Method for preparing an electrode using epoxy resin (thermosetting) combined with platinum nanoparticles

[0177] The method of Example 5 was followed, except that the carbon nanofibers were replaced with an equal amount of platinum nanoparticles.

[0178] Example 18 - Method for preparing an electrode using epoxy resin (thermosetting) combined with platinum nanoparticles

[0179] The method of Example 6 was followed, except that the carbon nanofibers were replaced with an equal amount of platinum nanoparticles.

[0180] Example 19 - Method for preparing a counter electrode using polyetherketone combined with carbon nanotubes

[0181] The surface resistivity is 10 2 -104 Ω and volume resistivity is 10 3 –10 5 Ω / cm, supplemented / combined with carbon nanotubes (TECAPEEK ELS nano ) of the polyetherketone rod was turned and cut until a ring with an inner diameter of 23 mm and an outer diameter of 25 mm was obtained (see Figure 2 The ring is mounted on the probe holder, and the wires required for the electrical connection are inserted into the appropriate grooves. Electrical contact and hydraulic sealing are ensured by a two-component conductive epoxy-based adhesive filled with carbon black nanoparticles.

[0182] Example 20 - Method for preparing a counter electrode using polyetherketone combined with carbon fiber

[0183] Following the procedure of Example 19, TEKAPEEK ELS CF30 Replacement for TECAPEEK ELS nano

[0184] Example 21 - Determination of free chlorine using an electrochemical probe wherein the counter electrode is obtained according to the method of Example 19

[0185] The term free chlorine refers to the sum of hypochlorous acid and hypochlorite ions formed by adding substances such as sodium hypochlorite, calcium hypochlorite, gaseous chlorine, and isocyanuric acid derivatives (dichlor and trichlor) to aqueous solution.

[0186] Two electrochemical probes are used for the determination of free chlorine:

[0187] - the first probe used is a probe known in the art (organic and inorganic free chlorine probe; Tecnosenss.rl, models NCL T20 e NCL T2, available at http: / / www.tsens.eu), in which the working electrode is a gold electrode, the reference electrode is a silver electrode and the counter electrode is a steel electrode;

[0188] - The second probe used was a probe known in the art, wherein the steel counter electrode was replaced by a polymer matrix counter electrode obtained using the method described in Example 19 of the present invention.

[0189] The measurement is carried out by inserting a probe into a hydraulic circuit in which the free chlorine content present in the water is varied.

[0190] Results obtained using probes known in the art such as Figure 4 As shown, the results obtained using the probe of the present invention are as follows Figure 5 shown.

[0191] The graph shows the measurement system signal output changes in time as the concentration of free chlorine in the water being analyzed changes.

[0192] It is known to those skilled in the art that the change in the signal is due to a reduction reaction.

[0193] The pH value when conducting the test was between 4 and 10; the temperature value was maintained between 0°C and 45°C.

[0194] The obtained results show that, by measuring with a probe using the polymer matrix electrode of the present invention, in the following cases:

[0195] - a measuring range between 0.010 and 2.000 ppm and between 0.05 and 20 ppm (end points inclusive);

[0196] - in the pH range of the analytical water between 4 and 10 (the dependence of the sensitivity on changes in pH is known to those skilled in the art);

[0197] - The signal slope varies within ±50% relative to the nominal slope;

[0198] - in the temperature range of 0 to 45°C;

[0199] Similar measurement results / values were obtained as those obtained with a prior art probe employing a steel counter electrode.

[0200] In this experimental model, increasing the concentration of dissolved salts in water, different behavior was observed between the prior art probe (steel counter electrode) and the probe where the counter electrode was the polymer matrix electrode of the present invention.

[0201] In fact, when the salts dissolved in the water exceed a value of 10,000 ppm, corrosion products are formed on the steel counter electrode, rendering the steel electrode of the probe unusable, whereas the probe employing the polymer matrix counter electrode of the present invention shows no corrosion products and can therefore still be used for free chlorine measurement.

[0202] After one month of measurement, the counter electrode according to the present invention continued to show no signs of corrosion at salt concentrations in the water greater than 10,000 ppm.

[0203] Example 22 - Determination of free chlorine using an electrochemical probe comprising a counter electrode obtained as described in Example 20 of the present invention

[0204] Two electrochemical probes for the determination of free chlorine were used according to the method described in Example 21, wherein:

[0205] - the first probe used is a probe known in the art (organic and inorganic free chlorine probe; Tecnosenss.rl, models NCL T20 e NCL T2, available at http: / / www.tsens.eu), in which the working electrode is a gold electrode, the reference electrode is a silver electrode and the counter electrode is a steel electrode;

[0206] The second probe used was a probe known in the art, wherein the steel counter electrode was replaced by a polymer matrix counter electrode of the present invention obtained using the method described in Example 20.

[0207] The results obtained are similar to those reported in Example 21 and are shown in Figure 6 middle.

[0208] Figure 6 Shows the measurement system signal output changing in time as the concentration of free chlorine in the water being analyzed changes.

[0209] Also in this example, the polymer matrix counter electrode of the present invention exhibited corrosion resistance as in Example 21.

[0210] Example 23 - Determination of free chlorine using the novel polymer-based reference electrode obtained as described in Example 11

[0211] For the determination of free chlorine, the method described in the previous examples was followed using a silver polymer-based reference electrode obtained as described in Example 11.

[0212] The results obtained are comparable to those reported in Examples 21-22.

[0213] As described above, the reference electrode (including the electrode of the present invention) is immersed in an electrolyte solution, which protects and allows the electrode to function.

[0214] The advantage of using the reference electrode of the invention instead of the silver electrodes present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0215] Example 23 - Determination of free chlorine using the novel working electrode of Example 14

[0216] The gold working electrode of the prior art probe was replaced with the working electrode obtained as described in Example 14 and used to measure free chlorine according to the method described in Example 21.

[0217] The results obtained are comparable to those reported in Examples 21-22.

[0218] As described above, working electrodes, including those of the present invention, are immersed in an electrolyte solution that protects and allows the electrode to function.

[0219] The advantage of using the working electrode of the invention instead of the gold electrodes present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0220] Example 24 - Determination of Free Chlorine Using the Counter Electrode of Example 19 and the Reference Electrode of Example 11

[0221] The counter electrode of Example 19 and the reference electrode of Example 11 were used to replace the counter electrode and reference electrode of the prior art probe and used to determine free chlorine according to the method described in Example 21.

[0222] The results obtained are comparable to those reported in Examples 21-23.

[0223] The polymer matrix of the present invention exhibits corrosion resistance against electrodes such as the electrode in Example 21.

[0224] Moreover, the advantage of using the reference electrode of the invention instead of the silver electrodes present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0225] Example 25 - Determination of Free Chlorine Using the Novel Counter Electrode of Example 19 and the Novel Working Electrode of Example 14

[0226] The counter electrode of Example 19 and the working electrode of Example 14 were used to replace the counter electrode and working electrode of the prior art probe and used to measure free chlorine according to the method described in Example 21.

[0227] The results obtained are comparable to those reported in Examples 21-24.

[0228] Also in this example, the polymer matrix counter electrode of the present invention exhibited corrosion resistance as in Example 21.

[0229] Moreover, the advantage of using the working electrode of the invention instead of the gold electrodes present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0230] Example 26 - Determination of Free Chlorine Using the Novel Reference Electrode of Example 11 and the Novel Working Electrode of Example 14

[0231] For the determination of free chlorine, the method described in Example 21 was followed, using the reference electrode of Example 11 and the working electrode of Example 14 instead of the silver reference electrode and working electrode of the prior art probe.

[0232] The results obtained are comparable to those reported in Examples 21-25.

[0233] Also in this case, the advantage of using the reference and working electrodes of the invention instead of the silver and gold electrodes, respectively, present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0234] Example 27 - Determination of Free Chlorine Using the Novel Reference Electrode of Example 11, the Novel Working Electrode of Example 14, and the Novel Counter Electrode of Example 19

[0235] For the determination of free chlorine, the method described in Example 21 was followed, using the reference electrode of Example 11, the working electrode of Example 14, and the counter electrode of Example 19 instead of the silver reference electrode, gold working electrode, and steel counter electrode of the prior art probe.

[0236] The results obtained are comparable to those reported in Examples 21-26.

[0237] Also in this case, the advantage of using the reference and working electrodes of the invention instead of the silver and gold electrodes, respectively, present in the probes known in the art is associated with a significant reduction in the costs of the raw materials used to prepare the electrodes and of the industrial process.

[0238] Example 28 - Determination of free chlorine using the novel counter electrode of Example 10, the reference electrode of Example 11, and the working electrode of Example 1

[0239] For the determination of free chlorine, the method described in Example 21 was followed, using the counter electrode of Example 10, the reference electrode of Example 11, and the working electrode of Example 1 instead of the electrodes of the probe known in the prior art.

[0240] The results and advantages obtained are comparable to those reported in Examples 25-27.

[0241] Example 29 - Determination of free chlorine using the novel counter electrode of Example 1, the reference electrode of Example 11, and the working electrode of Example 10

[0242] For the determination of free chlorine, the method described in Example 21 was followed, using the counter electrode of Example 1, the reference electrode of Example 11, and the working electrode of Example 10 instead of the electrodes in the probe known in the prior art.

[0243] The results and advantages obtained are comparable to those reported in Examples 25-27.

Claims

1. A method for preparing a polymer matrix electrode, the method comprising: Adding conductive metal and / or non-metallic materials to a polymer matrix in liquid form, wherein - the polymer matrix is selected from the group consisting of acrylonitrile-butadiene-styrene copolymers, ethylene-vinyl acetate copolymers, polyacetal, polyamide 6, polyamide 66, polyamide 12, polyamide, polybutylene terephthalate, polycarbonate, polyetherketone, polyetheretherketone, polyethersulfone, polyethylene, low-density polyethylene, high-density polyethylene, polyphenylene sulfide, polyoxymethylene, polypropylene homopolymer or copolymer, polyvinylidene fluoride, and any possible combination thereof; - the conductive metal and / or the non-metallic material is selected from the group consisting of: carbon; graphene; carbon fullerene; silver; copper; gold; aluminum; zinc; chromium; tin; iridium; tungsten; nickel; iron; platinum; lead; aluminum tin oxide (AZO); indium tin oxide (ITO); conductive ceramics; the conductive metal and / or non-metallic material is added in an amount in the range of 0.00%-40% based on the polymer material, optionally in an amount in the range of 0.1-35%, more optionally in an amount in the range of 1-30%, wherein: - the carbon is in the form of carbon fibers, carbon nanofibers, carbon nanotubes, carbon black, carbon nanoclay or carbon nanohorns; - the graphene is in the form of graphene, graphene oxide, graphene nanosheets or fullerene; - the metal is in the form of a powder, dispersion, gel, granules, microparticles or nanoparticles and / or nanowires; - the conductive ceramic is in the form of a powder, dispersion, gel, granules, microparticles or nanoparticles and / or nanowires; The mixture thus obtained is kept under stirring for a period of 1 to 120 minutes, and The stirred mixture was poured into molds.

2. The method of claim 1, wherein the electrode is prepared by machining after molding.

3. The method of claim 1 , further comprising adding one or more excipients, diluents, colorants, hardeners, glues, elasticizers, oils, metal salts, and / or fluidizing agents; and / or one or more heat treatments.

4. An electrode prepared by the method of claim 1. The electrode according to claim 4 , which is a working electrode, a counter electrode or a reference electrode.

6. An electrochemical sensor comprising at least the electrode according to claim 4.

7. The electrochemical sensor according to claim 6, further comprising a battery-based or battery-free detection and data transmission system.

8. The electrochemical sensor of claim 7, wherein the signal changes received by the detection and data transmission system are transmitted via a data transmission wire.

9. The electrochemical sensor of claim 7, wherein the signal changes received by the detection and data transmission system are transmitted via a wireless system.

10. The electrochemical sensor according to claim 6, further comprising at least one electronic control unit, at least one display, optionally a touch screen, and at least one measurement channel for detecting electrochemical parameters.

11. Use of a polymer matrix selected from the group consisting of acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl acetate copolymer, polyacetal, polyamide 6, polyamide 66, polyamide 12, polyamide, polybutylene terephthalate, polycarbonate, polyetherketone, polyetheretherketone, polyethersulfone, polyethylene, low-density polyethylene, high-density polyethylene, polyphenylene sulfide, polyoxymethylene, polypropylene homopolymer or copolymer, polyvinylidene fluoride, and any possible combination thereof in preparing a polymer matrix electrode selected from the group consisting of a counter electrode, a reference electrode and a working electrode, wherein the polymer matrix electrode is prepared by the method of claim 1.

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