NEW POLYMER MATRIX ELECTRODES

Abstract

Electrochemical probes (or sensors), resistant to corrosive agents present in seawaters or in industrial waters, useful for detecting compounds present in water, are here described, wherein said probes comprise at least one polymer matrix electrode, in which said electrode is selected from the group comprising counter electrode, reference electrode and working electrode.

Claims

1. A method for preparing a polymeric matrix electrode comprising: adding to a polymer matrix in liquid form an electric conductive metallic and/or a non-metallic material, wherein the polymeric matrix is selected from the group consisting of: ethyl acrylate polymer, acrylonitrile-butadiene or styrene butadiene copolymer, cellulose, epoxy resin, ethylene acrylic acid copolymer, fluoropolymer, natural rubber, melamine formaldehyde or melamine resin, hydrogenated nitrile rubber, polyethylene oxide or PEG, poly(4-methyl-1-pentene), polybutylene, polyacetal, polyacetylene, polyacrylic acid, polyacrylonitrile, polyamide 6, polyamide, polyaniline, polybenzimidazole, polybutadiene, polybutylene terephthalate, polycarbonate, polychloroprene, polydimethylsiloxane (silicones), polyepichlorohydrin, saturated and unsaturated polyester, polyetherketone, polyetherimide, polyethylene, low-density polyethylene, chlorosulfonated polyethylene, high-density polyethylene, poly(3,4-ethylenedioxythiophene), polyethylene terephthalate, polyphenylene sulfide, poly(phenylene oxide), polyphenylsulfone, polyisoprene, polyisothianaphene, phenolic/formaldehyde polymers, poly(methyl methacrylate), polyoxymethylene, poly(p-phenylene), poly-p-phenylene sulphide, poly(p-phenylene) vinylene, polypyrrole, polypropylene, polystyrene, polytetrafluoroethylene, polythiophene, polyurethane or amino, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, ethylene propylene copolymer, urea-formaldehyde polymers, urethane polyester or urethane polyether, and any of their possible combinations; the electric conductive metallic and/or the non metallic material is selected from the group consisting of: carbon; carbon nanotubes; carbon nanohorn; carbon black; graphene; fullerene; silver; copper; gold; aluminium; zinc; chrome; tin; iridium; tungsten; nickel; iron; platinum; lead; aluminium-tin oxide (AZO); and indium-tin oxide (ITO); wherein said electric conductive metallic and/or non metallic material is added at a dose of between 0.00% to 40%; wherein: the carbon is in the form of carbon fiber, carbon nano-fiber, carbon nanotubes, carbon black, carbon nano-clays or carbon nano-horn, the graphene is in the form of graphene, graphene oxide, graphene, nano platelets or fullerene, the metal is in the form of powder, dispersion, gel, particles, microparticles or nanoparticles and/or nanowire, the conductive ceramics are in the form of powder, dispersion, gel, particles, micro-particles or nanoparticles and/or nanowire; maintaining the mixture so obtained under stirring, for a time period of 1-120 minutes, and putting the stirred mixture into a mould.

2. The method according to claim 1, in which after moulding the electrode is prepared by machining.

3. The method according to claim 1, further comprising adding one or more excipients, diluents, staining, hardening, gum, elasticizing, oil, metallic salts, and/or fluidificants; and/or one or more thermic treatment.

4. The method according to claim 1, wherein in which the polymeric matrix is selected from the group consisting of comprising: Tecapeek ELS CF30 Black®, Tecapeek ELS nano Black®, Tecaform AH ELS Black®, Tecaflon PVDF ELS black; Tecapeek SD Black®, LARAMID K/40 HM®, LARPEEK 10 K/20®, 20 LARPEEK 10 K/30®, LARPEEK 10 K/40®, LARTON K/20®, LARTON K/30®, LARTON K/40 HM®, LARTON L K/20®, LASTILAC RT K/10®, LATAMID 66 H2 K/20®, LATAMID 66 H2 K/30®, LATAMID 66 H2 K/40®, LATAMID 66 H2 K/50®, LATER 4 K/30®, LATICONTHER 52/11 GR/70®, LATICONTHER 62 GR/50®, LATICONTHER 62 GR/50-V0®, LATICONTHER 62 GR/70®, LATICONTHER 75 GR/50®, LATICONTHER 80 GR/50®, LATICONTHER 87/28 GR/50®, LATIGRAY 82-03 CW/95®, LATIGRAY 82-03 CW/96 F3®, LATIGRAY 82-05 CX/90®, LATILUB 87/28-17ST K/15®, LATIMASS 82-05 D040®, LATIOHM 57-05 PD01 G/15®, LATIOHM 62-03 PD01 G/20®, LATIOHM 66-04 PD01 G/25-V0CT1®, LATIOHM 66-07 PD08 G/30®, 5 LATIOHM 73-09 PD01G/20®, LATIOHM 75/4-03 PD01 G/20®, LATIOHM 75/4-08 PD01 G/30®, LATIOHM 80-04 PD01 G/30®, LATIOHM 80-05 CNT GCE/500®, LATIOHM 82-02 PD09®, LATIOHM 85-06 PD01 G/15®, LATIOHM 87/26-06 PD01-V1®, LATIOHM 87/28-05 PD01 G/10®, LATIOHM 88/10-06 CNT®, LATIOHM 90/13-09 PD01 10 G/10®, LATISHIELD 36/AR-08A G/17-V0E®, LATISHIELD 36/AR-10A-V0E®, LATISHIELD 36/SP-05A®, LATISHIELD 38/11-08A G/10®, LATISHIELD 52/5-07A®, LATISHIELD 66-08A G/25-V0KB1®, LATISHIELD 66-10A®, LATISHIELD 66-10A G/15®, LATISHIELD 66-10A H2 CETG/400®, LATISHIELD 66-13A G/30®, LATISHIELD 73/13-07A®, LATISHIELD 75/4-10A®, LATISHIELD 85-08A 15 G/20®, LATISHIELD 87/28-10A®, LATISHIELD 87/28-10A G/20®, LATISTAT 36/MR-04®, LATISTAT 45/7-02®, LATISTAT 47/7-03®, LATISTAT 48/9900-03®, LATISTAT 52/7-02®, LATISTAT 52/7-02 MI/30®, LATISTAT 62-06 K/10®, LATISTAT 66-06®, LATISTAT 83-05® and LATISTAT 87/28-06.

5. An electrode prepared by the method according to claim 1.

6. The electrode according to claim 5, which is a working electrode, a counter electrode or a reference electrode.

7. An electrochemical sensor comprising at least an electrode according to claim 5.

8. The electrochemical sensor according to claim 7, further comprising a detection and transmission data system with a battery or “battery free type”.

9. The electrochemical sensor according to claim 7, wherein the signal variation received by the detection and transmission data system is transferred by electrical wire for data transfer.

10. The electrochemical sensor according to claim 7, further comprising at least an electric control unit, at least a display, optionally touchscreen, at least at least one channel of measurement for the detection of the electrochemical parameters.

11. (canceled)

12. The method according to claim 1, wherein the electric conductive metallic and/or non metallic material is added at a dose of between 0.1-35%.

13. The method according to claim 1, wherein the electrive conductive metallic and/or non metallic material is added at a dose of 1-30%.

14. The electrochemical sensor according to claim 9, wherein the signal variation received by the detection and transmission data system is transferred by a wireless system.

Description

DESCRIPTION OF THE FIGURES

[0118] In FIG. 1, the electrochemical probe according to the present invention is shown in which:

[0119] number 1 indicates the counter electrode made of a “polymer matrix”,

[0120] number 2 indicates the reference electrode made of a “polymer matrix”,

[0121] number 3 indicates the working electrode made of a “polymer matrix”, and number 4 indicates the electrical connection zone.

[0122] FIG. 2 shows an example of a “polymer matrix” counter electrode,

[0123] In FIG. 3 are shown, in more detail manner, the three electrodes, made of a “polymer matrix” according the present invention, in which:

[0124] number 1 indicates the counter electrode,

[0125] number 2 indicates the reference electrode, and

[0126] number 3 indicates the working electrode.

[0127] FIG. 4 shows the trend over time of the measurement system signal output, varying the free chlorine concentration in the analysed 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 a probe known to the art.

[0128] FIG. 5 shows the trend over time of the variation of the measurement system output signal using a probe known in the art wherein the counter electrode was prepared using a compound according to the present invention (PEEK modified with carbon nanotubes, see Example 19);

[0129] while the reference electrodes and working electrodes were those known in the art; the concentration of free chlorine in the water analyzed was: 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.

[0130] FIG. 6 shows the trend over time of the variation of the measurement system output signal by using a probe known in the art wherein the counter electrode was prepared using a compound according to the present invention (carbon fibres filled PEEK, see Example 20); while the reference and working electrodes were those known in the art; the concentration of free chlorine in the analysed water was: 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.

DETAILED DESCRIPTION OF THE INVENTION

Examples

Example 1

[0131] Method of Preparation of an Electrode by Using Polyvinylidene Fluoride (PVDF) (Thermoplastic) in Combination with Carbon Black

[0132] 610 mg of CB in 60 ml of DMF (N,N-dimethylformamide) were dispersed, the resulting suspension was sonicated (30% amplitude with a power of 200 W) in ice bath for at least one hour.

[0133] 5 g of PVDF pellets to the dispersion of sonicated CB were added.

[0134] The solution thus obtained was placed under gentle stirring for two hours at 90° C. and subsequently at 60° C. until evaporation of the solvent.

[0135] The solid thus obtained was collected and cut into pellet form.

[0136] The pellet was placed in a screw extruder and brought to the moulding temperature of about 175° C., to be moulded in the desired shape.

[0137] The semi-finished product thus obtained was mechanically refined to obtain an electrode having the desired shape and size, ready to be connected to the electronic measuring device.

Example 2

[0138] Method of Preparation of an Electrode, by Using Polyvinylidene Fluoride (PVDF) in Combination with Carbon Nanotubes

[0139] Following the method described in Example 1, using 122 mg of carbon nanotubes, an electrode having the desired shape and size, ready to be connected to the electronic measuring device was obtained.

Example 3

[0140] Method of Preparation of an Electrode Based on PET (Thermoplastic) Polyethylene Terephthalate in Combination with Carbon Nanotubes

[0141] Following the method of Example 2, but replacing PVDF with PET (polyethylene terephthalate), an electrode having desired shape and size, ready to be connected to the electronic measuring device was obtained.

Example 4

[0142] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanofibers

[0143] 498 mg of carbon nanofibers were dispersed in 50 ml of diethylene glycol butyl ether (BGE) and sonicated for one hour in an ice bath (with a 30% amplitude and 200 W power). 10 g of epoxy resin (DGEBA Araldite LY554®) in the dispersion of BGE and carbon nanofibers were added.

[0144] The compound thus obtained was kept under stirring at room temperature until complete evaporation of the BGE solvent.

[0145] in a dispersion of resin and carbon nanofibers, 6 g of hardener (Araldite HY956® triethyleneamines) were added; the resulting compound so obtained was subjected to gentle mechanical stirring for 5 minutes, and then poured into an electrode-shaped mold.

[0146] After 24 hours at room temperature the final shape of the electrode, ready to be connected to the electrical measuring system, was obtained.

Example 5

[0147] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanofibers

[0148] Following the method of Example 4, the BGE solvent was removed mechanically by filtering the dispersion of carbon nanofibers and BGE.

[0149] The carbon nanofibers, disentangled by sonication were collected on the filter paper and allowed to dry. After drying the fibres were dispersed in the resin by mechanical stirring.

Example 6

[0150] Method of Preparation of an Electrode by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanofibers

[0151] Following the method of Example 5, the carbon nanofibers were dispersed in the hardener instead of the resin, dispersed by mechanical stirring and then added to the resin.

Example 7

[0152] Method of Preparation of an Electrode by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanotubes

[0153] Following the method of Example 4, the carbon nanofiber was replaced with an equal amount of carbon nanotubes.

Example 8

[0154] Method of Preparation of an Electrode by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanotubes

[0155] Following the method of Example 5, the carbon nanofiber was replaced with an equal amount of carbon nanotubes.

Example 9

[0156] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Carbon Nanotubes

[0157] Following the method of Example 6, the carbon nanofiber was replaced with an equal amount of carbon nanotubes.

Example 10

[0158] Method of Preparation of an Electrode by Using an Epoxy Resin (Thermosetting) in Combination with Silver Nanopowder

[0159] Following the method of Example 4, the carbon nanofiber was replaced with an equal amount of silver nanopowder.

Example 11

[0160] Method of Preparation of an Electrode by Using an Epoxy Resin (Thermosetting) in Combination with Silver Nanopowder

[0161] Following the procedure of Example 5, the carbon nanofiber was replaced with an equal amount of silver nanopowder.

Example 12

[0162] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Silver Nanopowder

[0163] Following the method of Example 6, the carbon nanofiber was replaced with an equal amount of silver nanopowder.

Example 13

[0164] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Gold Nanoparticles

[0165] Following the method of Example 4, the carbon nanofiber was replaced with an equal amount of gold nanoparticles.

Example 14

[0166] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Gold Nanoparticles

[0167] Following the method of Example 5, the carbon nanofiber was replaced with an equal amount of gold nanoparticles.

Example 15

[0168] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Gold Nanoparticles

[0169] Following the method of Example 6, the carbon nanofiber was replaced with an equal amount of gold nanoparticles.

Example 16

[0170] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Platinum Nanoparticles

[0171] Following the method of Example 4, the carbon nanofiber was replaced with an equal amount of platinum nanoparticles.

Example 17

[0172] Method of Preparation of an Electrode, by Using an Epoxy Resin (Thermosetting) in Combination with Platinum Nanoparticles

[0173] Following the method of Example 5, the carbon nanofiber was replaced with an equal amount of platinum nanoparticles.

Example 18

[0174] Method of Preparation of an Electrode, Using an Epoxy Resin (Thermosetting) in Combination with Platinum Nanoparticles

[0175] Following the method of Example 6, the carbon nanofiber was replaced with an equal amount of platinum nanoparticles.

Example 19

[0176] Method of Preparation of a Counter Electrode, by Using a Polyetherketone in Combination with Carbon Nanotubes

[0177] A polyetherketone bar supplemented/combined with carbon nanotubes (TECAPEEK ELS nano Black®), having a surface resistivity of 10.sup.2-10.sup.4Ω and a Volume Resistivity 10.sup.3-10.sup.5 Ω/cm, was subjected to turning and cutting until a ring of internal diameter of 23 mm and external diameter of 25 mm was obtained (see FIG. 2). The ring was housed on the probe seat and the wire necessary for electrical connection was inserted into a suitable groove. The electrical contact and the hydraulic seal were ensured by a two-component, electrically conductive epoxy resin-based adhesive filled with carbon black nanoparticles.

Example 20

[0178] Method of Preparation of a Counter Electrode by Using a Polyetherketone in Combination with Carbon Fibres

[0179] Following the procedure of Example 19, TECAPEEK ELS nano Black® was replaced with TEKAPEEK ELS CF30 Black®.

Example 21

[0180] Measurement of Free Chlorine, by Using an Electrochemical Probe in which the Counter Electrode was Obtained Following the Method of Example 19

[0181] The term free chlorine refers to the sum of the hypochlorous acid and the hypochlorite ions which are formed by adding, in aqueous solution,

[0182] substances such as: [0183] sodium hypochlorite; [0184] calcium hypochlorite; [0185] gaseous chlorine; [0186] isocyanuric acid derivatives (dichloro and trichloro).

[0187] Two electrochemical probes were used for the measurement of free chlorine, in which: [0188] the first probe used was a probe known in the art (free chlorine probe, organic and inorganic; Tecnosens s.r.l. model NCL T20 e NCL T2 available in http://www.tsens.eu) wherein the working electrode is in gold, the reference electrode is in silver, and the counter electrode in steel; [0189] the second probe used was the probe known in the art in which the steel counter electrode was replaced with a polymeric matrix counter electrode obtained using the method described in Example 19 according to the present invention.

[0190] The measurement was carried out by inserting the probes into a hydraulic circuit in which the free chlorine content present in the water was varied.

[0191] The results obtained with the probe known to the art are shown in FIG. 4 while the results obtained with the probe according to the present invention are shown in FIG. 5.

[0192] The images show the variation in time of the measurement system signal output as the concentration of free chlorine in the analysed water varies.

[0193] It is known to the skilled in the art that the variation of the signal is due to a reduction reaction.

[0194] The pH value at which the tests were carried out was between 4 and 10; the temperature value remained between 0° C. and 45° C.

[0195] The results obtained shows that by carrying out the measurements with the probe with the polymeric matrix electrode according to the invention in: [0196] a measurement range comprised between 0.010 and 2.000 ppm and between 0.05 and 20 ppm; [0197] a pH range of the water analysed: 4-10 (to the skilled in the art the dependence of the sensitivity on variation of the pH is known); [0198] with a signal slope varying between ±50% with respect to the nominal slope; [0199] with a temperature range: between 0 and 45° C.;

[0200] measurements/values similar to those obtained with the probe of the art with a steel counter-electrode were obtained.

[0201] In this experimental model increasing the concentration of dissolved salts in water, different behaviours were observed between the prior art probe (steel counter electrode) and the probe in which the counter electrode was in a polymeric matrix according to the invention.

[0202] In fact, when the value of 10,000 ppm of salts dissolved in water were exceeded, corrosion products were formed on the steel count electrode made the probe steel electrode unusable; while the probe with a polymeric matrix counter electrode according to the invention showed no corrosion product, it was then usable for further measurements of free chlorine.

[0203] After one month of measurements, in the presence of a salt concentration in water greater than 10,000 ppm, the counter electrode according to the invention continued to show no sign of corrosion.

Example 22

Measurement of Free Chlorine Using an Electrochemical Probe Comprising the Counter Electrode Obtained as Described in Example 20 According to the Invention

[0204] Following the method described in Example 21, two electrochemical probes for the measurement of free chlorine were used, in which: [0205] the first probe used was a probe known in the art (free chlorine probe, organic and inorganic; Tecnosens s.r.l. model NCL T20 e NCL T2 available in http://www.tsens.eu) where the working electrode is in gold, the reference electrode is in silver, and the counter electrode is in steel; [0206] the second probe used was the probe known in the art, in which the steel counter electrode was replaced with a polymeric matrix counter electrode according to the present invention, obtained using the method described in Example 20.

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

[0208] FIG. 6 shows the variation in time of the measurement system signal output as the free chlorine concentration in the analysed water varies.

[0209] Also in this case, the polymeric matrix counter electrode according to the invention showed corrosion resistance as in Example 21.

Example 23

Measurement of Free Chlorine Using the New Reference Electrode in Polymer Matrix Obtained as Described in Example 11

[0210] For the measurement of free chlorine, following the method described in the previous Examples, a reference electrode in a silver polymeric matrix, obtained as described in Example 11, was used.

[0211] The results obtained were comparable to those reported in Examples 21-22.

[0212] As stated above, the reference electrode (including that of the present invention) is immersed in an electrolytic solution, which protects and allows its function.

[0213] The advantage in the use of the reference electrode according to the present invention, in substitution of the silver electrode present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 23

Measurement of Free Chlorine Using the New Working Electrode of Example 14

[0214] The gold working electrode of the prior art probe was replaced with the working electrode obtained as described in Example 14 and used for the measurement of free chlorine following the method described in Example 21.

[0215] The results obtained were comparable to those reported in Examples 21-22.

[0216] As stated above, the working electrode (including that of the present invention) is immersed in an electrolytic solution, which protects and allows its function.

[0217] The advantage in the use of the working electrode according to the present invention, instead of the gold electrode present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 24

Measurement of Free Chlorine Using the Counter Electrode of Example 19 and the Reference Electrode of Example 11.

[0218] The counter electrode and the reference electrode of the prior art probe were replaced with the counter electrode of Example 19 and the reference electrode of Example 11, and used for the measurement of free chlorine following the method described in Example 21.

[0219] The results obtained were comparable to those reported in Example 21-23.

[0220] The polymeric matrix counter electrode according to the invention showed corrosion resistance such as that of Example 21.

[0221] Moreover, the advantage in the use of the reference electrode according to the present invention, instead of the silver electrode present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 25

Measurement of Free Chlorine Using the New Counter Electrode of Example 19 and the New Working Electrode of Example 14

[0222] The counter electrode and the working electrode of the prior art probe were replaced with the counter electrode of Example 19 and the working electrode of Example 14, and used for the measurement of free chlorine following the method described in Example 21.

[0223] The results obtained were comparable to those reported in Examples 21-24.

[0224] Also in this case, the polymeric matrix counter electrode according to the invention showed corrosion resistance as in Example 21.

[0225] Moreover, the advantage in the use of the working electrode according to the present invention, instead of the gold electrode present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 26

Measurement of Free Chlorine Using the New Reference Electrode of Examples 11 and the New Working Electrode of Example 14

[0226] For the measurement of free chlorine, following the method described in Example 21, the reference electrode of Example 11 and the working electrode of Example 14, in place of the silver reference electrode and the gold working electrode of the prior art probe were used.

[0227] The results obtained were comparable to those reported in Examples 21-25.

[0228] Also in this case the use of the reference electrode and the working electrode according to the present invention, in place of the silver and gold electrode, respectively, present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 27

Measurement of Free Chlorine Using the New Reference Electrode of Example 11, the New Working Electrode of Example 14 and the New Counter Electrode of Example 19

[0229] For the measurement of free chlorine, following the method described in Example 21, 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, the gold working electrode and the steel counter electrode of the prior art probe were used.

[0230] The results obtained were comparable to those reported in Examples 21-26.

[0231] Also in this case the use of the reference electrode and the working electrode according to the present invention, in place of the silver and gold electrode, respectively, present in the probes known in the art, is linked both to the significant reduction of the costs of the raw material and of the industrial method for preparing the electrode.

Example 28

Measurement of Free Chlorine Using the New Counter Electrode of Example 10; the Reference Electrode of Example 11, and the Working Electrode of Example 1

[0232] For the measurement of free chlorine, following the method described in Example 21, the counter electrode of Example 10; the reference electrode of Example 11; and the working electrode of Example 1 in place of the electrodes in the probe known to the art, was used.

[0233] The results and advantages obtained were comparable to those reported in Examples 25-27.

Example 29

Measurement of Free Chlorine Using the New Counter Electrode of Example 1; the Reference Electrode of Example 11, and the Working Electrode of Example 10.

[0234] For the measurement of free chlorine, following the method described in Example 21, 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 to the art, were used.

[0235] The results and advantages obtained were comparable to those reported in Examples 25-27.