ES2900851B2 - ELECTROCHEMICAL CELL FOR WASTEWATER TREATMENT AND ELECTROCHEMICAL PROCESS OF SURFACE MODIFICATION OF THE TEXTILE ELECTRODE CONTAINED IN SAID ELECTROCHEMICAL CELL - Google Patents

Description

DESCRIPTION

ELECTROCHEMICAL CELL FOR WASTEWATER TREATMENT

OBJECT OF THE INVENTION

The present invention refers to an electrochemical cell for the treatment of wastewater, specifically for the bleaching and reduction of organic load contained in the wastewater.

The system of the present invention is provided with textile electrodes that act as anode and cathode during the electrochemical process used for the treatment of wastewater. Of the textile electrodes, at least one of them is superficially modified by an electrochemical process in such a way that it presents an intermediate layer of electrochemically reduced graphene oxide and an external layer of electrochemically reduced metal nanoparticles.

The object of the present invention consists of an electrochemical cell that includes a surface-modified textile electrode, the electrochemical process of surface modification of the textile electrode contained in the electrochemical cell of the invention also being the object of the present invention.

BACKGROUND OF THE INVENTION

Wastewater receives different treatment processes depending on its origin, concentration and the class of pollutants it contains.

Among other contaminants, one of the most complex components to remove from wastewater is color.

In this sense, it should be noted that in standard dyeing processes, around 70% of the water used for the dyeing process is discarded. This means that the dyeing process consumes very large amounts of water, with a really low efficiency. In fact, enormous amounts of water are currently consumed to achieve favorable results in dyeing processes. Not only in the dyeing process as such, but also in subsequent cleaning and finishing processes of the dyed textile.

In fact, dyeing processes are known in which close to 50% of the synthetic dye ends up unused directly in wastewater, which leads to serious contamination of surface and groundwater near textile industries. Reason that forces its processing to avoid irreparable damage to the planet.

Traditionally, purification processes for water used for dyeing have been extremely expensive and completely unfeasible. In this sense, the usual procedure is the subcontracting of companies dedicated to the treatment of hazardous waste for the environment, with the high costs that these operations imply.

In an urban Wastewater Treatment Plant (WWTP), it is estimated that only between 20-30% of the color of the effluent is removed.

Dyes that are not soluble in water (disperse, vat, sulphurous, etc.) are eliminated in a primary stage of coagulation-decantation, while the most soluble will undergo biological treatment. Despite not being biodegradable (aerobically), a part of these dyes will be retained by a “bioelimination” mechanism, which consists of the adsorption of the dye to the biomass and its subsequent elimination in the sludge deposition. Some dyes are very little retained by the biomass (10-30%). A significant color reduction after a biological process is only possible if very expensive tertiary treatments are applied.

The most widely used treatments for wastewater treatment are the following:

- Coagulation-flocculation:

This technique depends on the concentration of the dye and the working pH. It generates a residue that requires additional post-treatment to be destroyed while the excess of inorganic salts used as coagulant increases the conductivity of the water.

- Adsorption with activated carbon:

This technique offers yields close to 95% of the total bleaching. However, activated carbon has a very high cost and a limited useful life. The adsorption of bulky molecules is easily carried out, but their desorption is more complicated and must be supported by pyrolysis processes. This technique is suitable for small volumes of influent.

- Membrane technologies:

Both nanofiltration and reverse osmosis are effective in retaining dyes and other textile products. These processes are capable of separating all kinds of soluble dyes. Specifically, there are nanofiltration processes in which discolorations close to 99% are achieved. However, a reverse osmosis process is necessary to achieve a significant reduction of the salt content in the permeate. These techniques present a high energy consumption and the generation of a new strongly colored effluent (of smaller volume, but higher concentration) that must be treated by pyrolysis. These methods are most useful in combination with other debugging processes.

- Treatment with ozone:

This technique is based on the excellent oxidation capacity of ozone (O ₃ ), which is capable of oxidizing dye molecules, breaking their bonds and producing colorless species, due to the formation of hydroxyl radicals (-OH). This technique achieves high bleaching in a fairly wide range of pH (between 4 and 12), but requires much longer process times to eliminate COD (Chemical Oxygen Demand), which implies very high energy consumption.

On the other hand, it is currently experimenting with different processes that are under study, the main methods being the following:

- Natural coagulants

The use of natural coagulants aims to replace processes based on traditional chemical coagulants with low-cost coagulants obtained from agricultural waste. The main drawback of this process is that it can considerably increase the organic load of the effluent.

- New adsorbents:

The process based on new adsorbents of biological origin is proposed as a substitute for the current active carbon.

- Enzymatic treatments:

The selection of specific microorganisms for dye degradation is an alternative to conventional biological treatment.

Generally speaking, it is not very efficient for color removal.

- Anaerobic reactors:

Some of the azo dyes can also be degraded in anaerobic bioreactors, by the action of methanogenic batteries. The main drawback of these processes are the amines that are generated, which have high toxicity.

- Advanced oxidation processes:

Advanced Oxidation Processes (POAs) are designed for the specific removal of persistent organic compounds that are resistant to conventional chemical or biological treatments. It consists of a chemical oxidation under conditions of pressure and ambient temperature, with which it is possible to reach the complete mineralization of the contaminants. The main objective of POAs is the degradation of recalcitrant compounds through the generation of an oxidizing agent, among which the radical called hydroxyl (·OH) stands out, which has a very high oxidizing capacity, is not selective and has very short reaction times, which makes POAs one of the most effective methods for treating wastewater laden with organic compounds.

These techniques use various oxidizing agents such as: ozone (O ₃ ), 03/hydrogen peroxide (H ₂ O ₂ ), 03/catalyst, ultraviolet radiation (UV), UV/O ₃ , UV/H ₂ O2 and also Iron Fe2+ /H202 and photocatalysis (heterogeneous or homogeneous).

Processes with photocatalysis (UV/H ₂ O ₂ /TiO ₂ ) and photolysis (UV/H ₂ O2) are highly effective, positioning themselves as the methods that cause the greatest effects in textile wastewater, resulting in optimal processes by involving a photocatalyst . These processes are characterized by their high cost in both reagents and energy.

- Electrochemical techniques:

They are advanced oxidation processes based on the electrolysis of the effluent. The molecules are normally partially oxidized, since their total mineralization implies an excessive electrical consumption. These processes are clean and operate at ambient conditions. In general, the destruction of organic compounds in water takes place by oxidation, which can be direct at the anode and/or indirect by species generated at the anode.

Electrochemical bleaching offers great advantages in the treatment of strongly colored textile wastewater, even more so when it comes from dyeing with reactive dyes that require the addition of chemical products (organic and inorganic) and does not generate waste or sludge.

On the contrary, it must be verified that the oxidizing products generated in the electrochemical process do not reduce the biodegradability of the effluent, nor do they give rise to inhibition phenomena that would cause operational problems in the subsequent biological treatment plant. The fundamental drawback of these processes is based on the efficiency of the systems.

Currently, very large sizes of the known textile electrodes are required to treat small volumes of waste water.

For all of the above, the applicant for this patent detects the need to propose a system that offers greater efficiency in terms of size/surface of the electrodes in electrolysis processes for wastewater treatment, which would enable a significant advance in the wastewater treatment capacity that allows solving the problems described above, providing an effective solution.

DESCRIPTION OF THE INVENTION

The electrochemical cell that is recommended has been conceived to solve the previously exposed problem in such a way that it allows the treatment of discoloration and reduction of the organic load of wastewater.

In this sense, the invention proposes an electrochemical cell that allows the treatment of a high volume of wastewater in an acceptable time for this type of process.

With the present invention it is achieved that the purification process through electrolysis can be carried out, both for industrial and urban wastewater, making it possible to reuse the water treated with the electrochemical cell of the invention, with the consequent economic savings and environmental benefits that it entails. Textile electrodes allow for a better area/mass and area/volume ratio, making systems more compact.

Additionally, the configuration of the electrochemical cell proposed in the present invention allows the use of electrical charges and shorter treatment times. Therefore, the energy consumption associated with the system of the present invention is lower than those of other known systems that use electrolysis processes for water treatment.

Specifically, in the configuration of the electrochemical cell of the present invention, at least the following elements participate:

- a sealed tank where the electrolysis process is carried out and through which a constant flow of wastewater to be treated is circulated, where said sealed tank is made up of an inert material to the electrochemical process,

- at least one inlet through which a constant forced flow of wastewater flows, - at least one outlet through which a constant forced flow of wastewater flows, - a booster pump that generates the constant forced flow of wastewater , - At least two independent meshes made of an electrically conductive material which is inert to electrochemical reactions, which are installed inside the sealed tank. Each mesh is provided with two electrical contacts,

- a power supply,

- At least two textile electrodes made up of electrically conductive fabrics and small ohmic drops. Thus, the textile electrodes are arranged inside the sealed tank facing each other to generate homogeneity in the electric field,

In this way, each mesh supports a textile electrode, the electrical contacts of the meshes being connected to the power supply.

The power supply feeds the meshes electrically with a constant and uniform electrical potential that is conducted to the textile electrodes for conduction over its entire surface. The textile electrodes are connected to a power source that generates between them the necessary potential difference for the electrochemical reactions to take place inside the sealed tank.

During wastewater treatment, the textile electrodes act one as an anode and the other as a cathode.

One of the notable differences that generate a surprising technical effect of the present invention is related to the need for at least one textile electrode of those that participate in the electrochemical cell to be superficially modified by an electrochemical process so that said textile electrode It features an intermediate layer of electrochemically reduced graphene oxide and an outer layer of electrochemically reduced metal nanoparticles.

It should be noted that textile electrodes are known to have a high area/volume and area/mass ratio. The advantage presented by the electrochemical cell of the present invention resides in the fact that the surface modification carried out in at least one of the textile electrodes makes it possible to improve their capacities and increase the performance for discoloration and reduction of the organic load of wastewater.

Thus, the presence of the textile electrode modified on the surface by an electrochemical process offers high dimensional versatility, being able to optimize the volumes of wastewater treatment, without the need for expensive manufacturing methods.

That is, the surface modification of the textile electrode increases the contact surface with the wastewater to be treated and significantly increases the efficiency of the electrochemical cell. In this way, the electrochemical cell makes it possible to treat much larger volumes with a much smaller cell size than any system without textile electrodes.

For all these reasons, and given the importance of the type of textile electrodes used in the electrochemical cell, the object of the present invention is the electrochemical process of surface modification of the aforementioned textile electrode contained in the electrochemical cell, which we will detail later.

On the other hand, it should be noted that the material that makes up the mesh is an electrical conductor and inert to electrochemical reactions in order to guarantee a constant potential on the entire surface of the textile electrode.

In this sense, it is essential for the efficiency of the electrochemical process both during wastewater treatment and during the electrochemical modification process. surface of the textile electrode that the potential is constant between the textile electrodes that work as anode and cathode.

It is known that textile electrodes, despite being conductive, have a higher ohmic drop than other materials. This problem leads to the fact that when a textile electrode is directly powered electrically, it does not maintain the potential homogeneously over its entire surface, because despite being a conductor, it presents a drop in this potential as we move away from the connection point. For this reason, two electrical contacts per mesh that supports each textile electrode are preferably proposed.

On the other hand, the non-rigid nature associated with the textile electrode requires the presence of a mesh, as previously detailed, which acts as a skeleton or support on which each textile electrode rests.

Obviously, the meshes are made of an electrically conductive material to generate a homogeneous distribution of the potential in the textile electrodes and currents inside the sealed tank or reactor. Thus, it is necessary to keep each textile electrode fixed to a mesh that allows the electrolyte to flow through it, and to keep the textile electrode in a suitable working position.

As mentioned above, the textile electrodes are supported on the meshes and arranged opposite each other, preferably being arranged 1 mm to 5 cm apart from each other. Thus, for a separation between textile electrodes greater than 5 cm, the textile electrodes will stop interacting with each other, and there will be no electrochemical reactions between them.

Another relevant factor to guarantee the correct functioning of the electrochemical cell lies in the fact that preferably the surface of each mesh (5) is partially covered by the textile electrode, in order to generate turbulence in the wastewater to be treated.

Due to all of the above, the electrochemical cell of the present invention is used for the treatment of wastewater, specifically for the bleaching and reduction of the organic load, and it can even be used in the treatment of industrial water derived from industrial dyeing processes. For this, the electrochemical cell is provided with at least one textile electrode modified on the surface through an electrochemical process that allows it to be provided with greater electrocatalytic power and that allows generating a surface protection that leads to a longer useful life of said textile electrode.

Next, we proceed to detail the stages that make up the electrochemical process of surface modification of the textile electrode contained in the electrochemical cell of the present invention:

- Arrangement of the textile electrodes supported on meshes and arranged facing each other.

- Filling of the sealed tank with a dispersion of graphene oxide (GO).

- Connection of the electrical contacts of the meshes to the power supply.

- Transfer of charge from the power source to the textile electrodes where one textile electrode acts as anode and another as cathode.

- Electrochemical reduction of graphene oxide to reduced graphene oxide (RGO), through a potentiodynamic process,

- Deposit of the RGO on the surface of the textile electrode that acts as cathode. - Emptying of the sealed tank.

- Cleaning of the sealed tank and the textile electrodes with pure water.

- Filling of the sealed tank with a solution containing metal cations, preferably platinum cations.

- Transfer of charge from the power source to the textile electrodes. - Electrochemical reduction of metal cations through a potentiodynamic process, obtaining metal nanoparticles.

- Deposit of metal nanoparticles on the surface of the textile electrode, which acts as a cathode during the electrochemical process of surface modification. - Emptying of the sealed tank.

- Washing of the sealed tank with pure water.

Advantageously, the graphene oxide dispersion and the metal cation-containing solution recovered after the electrochemical reductions can be preserved for later uses. In addition, by using the same electrochemical cell for the regeneration of the coatings and for the subsequent water treatment, the technical and economic feasibility of these processes is increased. It is common in other electrochemical cells that the electrode replacement stage is very technically and economically expensive.

On the other hand, it is relevant to indicate that the textile electrode superficially modified by the detailed electrochemical process acts as an anode in the electrochemical cell when the wastewater treatment is taking place. However, during the electrochemical surface modification process, the surface modified electrode acts as the cathode.

The invention presented here represents an advance in the state of the art of electrochemical cells for wastewater treatment and an advantage over the known ones, since it provides a solution to the technical problems presented by treatments for discoloration and reduction. of the organic load of the wastewater described above, thus offering an effective treatment for the elimination of dyes contained in the wastewater, minimizing the environmental impact that these generate in their treatment.

DESCRIPTION OF THE DRAWINGS

To complement the description that is going to be made below and in order to help a better understanding of the characteristics of the invention, according to a preferred example of its practical embodiment, a set of drawings is attached as an integral part of said description. where, with an illustrative and non-limiting nature, the following has been represented:

FIG 1.- Shows a schematic representation in section of an arrangement of the electrochemical cell of the invention according to a first preferred embodiment where the textile electrodes are arranged to form two concentric rings so that the wastewater to be treated radially crosses the concentric rings.

FIG 2.- Shows a schematic representation in section of some elements represented in the previous figure according to the first preferred embodiment of the invention.

FIG 3.- Shows a perspective and exploded view of some elements that make up the electrochemical cell according to a first preferred embodiment represented in the previous figures.

FIG 4.- Shows a perspective view of the assembled elements represented in figure 3.

FIG 5.- Shows a perspective view of a mesh that supports a textile electrode according to the configuration represented in the first preferred embodiment of the invention represented in the previous figures.

FIG 6.- Shows a perspective view of some elements that make up the electrochemical cell according to a second preferred embodiment in which the textile electrodes are arranged to form parallel planes between which the wastewater to be treated flows.

FIG 7.- Shows a lateral representation of the preferred embodiment represented in figure 6.

FIG 8.- Shows a front representation of the preferred embodiment represented in figure 6.

REFERENCE LIST

1. Watertight tank.

2. Inlet of the sealed tank.

3. Outlet of the sealed tank.

4. Drive pump.

5. Mesh.

6. Textile electrode.

7. Electrical contact.

8. Power supply.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

According to the outlined figures, we differentiate between two preferred, but not limiting, embodiments of the electrochemical cell of the present invention.

In this sense, figures 1, 2, 3, 4 and 5 correspond to a first preferred embodiment of the invention, where the meshes, and therefore the textile electrodes, are arranged to preferably form two concentric rings so that the water residual to be treated radially crosses the concentric rings.

On the other hand, figures 6, 7 and 8 correspond to the representation of a second preferred embodiment of the invention where the meshes, and therefore the textile electrodes, are arranged forming parallel planes between which the wastewater to be treated flows.

Figure 1 shows an electrochemical cell in accordance with the first preferred embodiment of the invention where the elements that are part of said electrochemical cell are fully represented, while Figure 2 represents the sealed tank (1) where the input ( 2) and the outlet (3) through which the residual water flows, the meshes (5) that have two electrical contacts (7) per mesh (5), leaving the electrical contacts (7) arranged on the outside of the sealed tank ( 1) to facilitate the connection to the power supply (8) represented in figure 1. As can be seen in figures 1 and 2, the electrochemical cell is made up of the following elements:

- A watertight tank (1).

- An inlet (2) through which a constant forced flow of wastewater flows.

- An outlet (3) through which a forced constant flow of wastewater flows.

- An impulsion pump (4) that generates the forced constant flow of wastewater. - A power supply (8).

- Two independent meshes (5) made up of an electrically conductive material which is inert to electrochemical reactions and where each mesh (5) is provided with two electrical contacts (7). The meshes (5) are in charge of transmitting the electrical current to the textile electrodes (6) and are preferably made of titanium.

- Two textile electrodes (6) made up of electrically conductive fabrics, the latter being preferably made up of activated carbon fabrics. The textile electrodes (6) are arranged facing each other to generate homogeneity in the electric field. Necessarily, at least one textile electrode (6) is superficially modified by an electrochemical process and presents an intermediate layer of electrochemically reduced graphene oxide and an external layer of electrochemically reduced metal nanoparticles. Preferably, the metal of the outer layer of electrochemically reduced metal nanoparticles is platinum.

The previously detailed elements are present both in the first and in the second preferred embodiment of the invention, where the electrical contacts (7) of the meshes (5) are connected to the power supply (8). In this way, the power source feeds the meshes (5) electrically with a constant electrical potential and uniform that is conducted to the textile electrodes (6), one textile electrode (6) acting as anode and another as cathode.

As can be seen in figures 3, 4 and 5, in a first embodiment of the invention, each mesh (5) supports a textile electrode (6) so that the meshes (5) are arranged to form two concentric rings. Or what is the same, each textile electrode (6) rests on a mesh (5) that allows defining a cylindrical geometry. Thus, the wastewater to be treated radially crosses the concentric rings.

Advantageously, the cylindrical arrangement of the textile electrodes (6) in concentric rings makes it possible to obtain a high ratio between the volume of the sealed tank (1) and the amount of textile electrode area (6) that can be achieved within it. For this purpose, in an embodiment not shown in the figures that accompany this report but which are also the object of the invention, the electrochemical cell is provided with more than one textile electrode that acts as anode and more than one textile electrode that acts as cathode, always keeping the total areas of anode and cathode approximately equal.

Also in figures 3, 4 and 5 we observe that, in the first preferred embodiment of the invention, the surface of each mesh (5) is partially covered by the textile electrode (6) so that this arrangement generates turbulence inside it, guaranteeing that it does not produce the decantation by gravity of the particles in suspension.

In the second preferred embodiment of the invention represented in figures 6, 7 and 8, the meshes (5) that support the textile electrodes (6) preferably form two parallel planes. In other words, each textile electrode (6) rests on a mesh (5) that makes it possible to define a flat geometry.

Although it is true that the arrangement of the textile electrodes (6) in the second preferred embodiment of the invention offers a lower maximum ratio of area per unit volume than the arrangement of the first preferred embodiment of the invention.

As can be seen in Figures 1 and 5, corresponding to the first and second preferred embodiments of the invention respectively, the inlet (2) and outlet (3) in the sealed tank (1) are arranged so that the inlet (2 ) is carried out at a point of lower height than the outlet (3) to generate turbulence. This arrangement also avoids settling by gravity previously mentioned, that is, we prevent the generation of different fluid densities and therefore we avoid an irregular behavior of the electrodes.

On the other hand, also in Figures 1 and 5 it can be seen that each mesh (5) is provided with two electrical contacts (7), a fact that allows an additional security of potential control during the operation of the electrochemical cell. Thus, in the event that one of the electrical contacts (7) is not properly connected to the power supply (8), it will be possible to identify it immediately thanks to the measurement obtained by the other electrical contact (7) that presents the mesh (5 ).

As distinguished in any of the preferred embodiments represented in the figures that accompany this report, the electrochemical cell of the invention is made up of a sealed (1) or hermetic tank where the electrochemical reactions take place. The sealed tank (1) is equipped with two holes through which the inlet (2) and the outlet (3) of the flow of wastewater to be treated take place.

The correct electrical supply of the meshes (5) is guaranteed, which feed the textile electrodes (6) with current. The connections between the elements that make up the electrochemical cell must be made hermetic and with the assurance that the residual water does not come into contact with any other element except the walls of the sealed tank (1) - made up of an inert material to the process electrochemical -, the meshes (5) and the textile electrodes themselves (6).

As previously indicated, the application of a power supply (8) that provides electrical current to the electrochemical cell is required for the effective treatment of wastewater to take place. Specifically, the power supply (8) will be connected to the meshes (5) to generate the potential difference between them that the electrolysis process requires.

Inside the sealed tank (1) it must be guaranteed that a short circuit cannot occur (contact of the electrodes) and there must be constant confirmation that the contact between the power supply (8) and the meshes (5 ) it's right.

The potential necessary for the electrochemical reactions to occur is stabilized and is kept constant during the wastewater treatment process. so the water The residual to be treated must be in contact with the textile electrodes to cause their discoloration and reduction of organic load.

Depending on the degree of coloration, organic load and type of colorant of the wastewater to be treated, a certain time must be maintained in treatment. It is important to distinguish that the process can be quantified in terms of "equivalent charge" which would be the amount of total energy consumed during the electrochemical treatment that has been provided to the system to carry out each of the processes.

A test carried out using the electrochemical cell of the invention is detailed below, which demonstrates its effectiveness for the treatment of wastewater.

Specifically, the wastewater to be treated contains a dye called Amaranth, with an electrolyte of sodium sulfate (SO ₄ Na2) with a concentration of 45 g/L.

In this test, 900 ml of wastewater have been treated in an electrochemical cell with a total internal volume of 628 ml. Inside this electrochemical cell there is a textile anode with a surface area of 157 cm2 (contemplating both sides of the electrically conductive fabric that integrates the textile electrode that acts as anode) and a cathode with a surface area of 251 cm2 (contemplating both sides of the electrically conductive fabric that integrates the textile electrode that acts as cathode).

The arrangement of the textile electrodes used in this test corresponds to a cylindrical geometry forming two concentric rings, the anode being a cylinder open at the ends with a diameter of 50 mm and the cathode a cylinder open at the ends with a diameter of 80 mm. Both with a height of 50 mm.

The electrochemical cell is correctly connected and sealed to begin with the circulation of the wastewater to be treated. It is connected to the power supply to the electrical contacts of the meshes in order to maintain the constant potential in the textile electrodes inside the sealed tank.

The textile electrodes are fed with constant potential, specifically in the test carried out, a potential of 3.9 V is applied, which generates an intensity of 0.9 A and proceeds to the forced circulation of the solution to be treated through the system. by means of a hydraulic pump.

With this process, and in a treatment time of 120 minutes, the following results were obtained:

- The initial concentration of Total Organic Carbon (TOC) (expressed in mg/L) is 29.14 mg/L, and the final one is 4.72 mg/L. This represents a reduction of 83.82% of the Total Organic Carbon.

- The initial concentration of the Chemical Oxygen Demand (COD) (expressed in mg/L) is 215.67 mg/L, and the final one is 92 mg/L. This represents a 57.34% reduction in the Chemical Oxygen Demand.

- As a criterion for complete discoloration, it has been considered that this occurs when only 1% of dye remains in the treated wastewater solution with its chromophore group without degrading. For the case presented, an electrical charge of 1,183 Ah/L has been required.

To obtain a more direct analysis of the efficiency of the electrochemical cell of the invention, the values are presented based on the area of the anode used:

The electrochemical cell of the present invention has an anode with a surface area of 157 cm2. With this area, it has been possible to treat a volume of residual water of 900 ml in a time of 120 minutes.

From these values, a relationship between the anode area and the volume of treated wastewater of 2.86 mL-h/cm2 is obtained. This relationship can serve as a guide when increasing the treatment volume of the electrochemical cell. Estimating that to treat a volume of wastewater of 1m3 in one hour, a sealed tank containing textile electrodes of around 2,860,000 cm2 would be required.

Should the treatment time increase, for example, up to 6 hours, the size of the textile electrode would be reduced to 476,666 cm2. As previously mentioned, the configuration of the electrochemical cell of the invention allows different textile electrodes to be placed concentrically, optimizing the surface of the textile electrode based on the total volume inside the sealed tank.

Claims (8)

1. - Electrochemical cell for wastewater treatment characterized by comprising: - a watertight tank (1), - at least one inlet (2) through which a constant forced flow of wastewater flows, - at least one outlet (3) through which a constant forced flow of wastewater flows, - a drive pump (4) that generates the forced constant flow of wastewater, - at least two independent meshes (5) made of an electrically conductive material which is inert to electrochemical reactions, where each mesh (5) is provided with two electrical contacts (7), - a power supply (8), - At least two textile electrodes (6) made up of electrically conductive fabrics, the textile electrodes (6) being arranged facing each other to generate a homogeneous electric field, where each mesh (5) supports a textile electrode (6), such that the surface of each mesh (5) is partially covered by the textile electrode (6) and each mesh (5) has two electrical contacts (7); the electrical contacts (7) of the meshes (5) being connected to the power source (8) in such a way that it feeds the meshes (5) electrically with a constant and uniform electrical potential that is conducted to the textile electrodes (6) , where a textile electrode (6) acts as anode and another as cathode, and where at least one textile electrode (6) is superficially modified by an electrochemical process and has an intermediate layer of electrochemically reduced graphene oxide and an outer layer of electrochemically reduced metal nanoparticles. 2. - Electrochemical cell for wastewater treatment, according to claim 1, characterized in that the meshes (5) are arranged to form two concentric rings, so that the wastewater to be treated radially crosses the concentric rings.3 3. - Electrochemical cell for wastewater treatment, according to claim 1, characterized in that the meshes (5) are arranged forming parallel planes between which the wastewater to be treated flows. 4- Electrochemical cell for wastewater treatment, according to any of the preceding claims, characterized in that the mesh (5) is made of titanium. 5. Electrochemical cell for wastewater treatment, according to claim 1, characterized in that the textile electrodes (6) that are supported on the meshes (5) and arranged opposite each other, are separated from each other with a distance between 1 mm and 5 cm. 6. - Electrochemical cell for wastewater treatment, according to claim 1, characterized in that the electrically conductive fabrics of the textile electrodes (6) are made up of activated carbon fabrics. 7. - Electrochemical cell for wastewater treatment, according to claim 1 or 6, characterized in that the metal of the outer layer of electrochemically reduced metal nanoparticles is platinum. 8. - Electrochemical cell for wastewater treatment, according to claim 1, characterized in that the inlet (2) is made at a point of lower height than the outlet (3) to generate turbulence.