CN1329576A - Electrolysis device and method for purifying aqueous solutions and synthesizing chemicals - Google Patents

Abstract

Electrical purification of contaminated aqueous media, such as ground water and wastewater from industrial production facilities, such as paper mills, food processing plants and textile mills, is accomplished by an improved, more economical open-structured electrolytic cell design having several electrically conductive porous elements electrically connected to each other to immediately purify, decolorize and disinfect the aqueous media. The cells may be divided or undivided and connected in a monopolar or bipolar configuration. When electrically coupled with a very narrow capillary gap, more economical operation can be ensured, especially when handling very low conductivity solutions. The new cell design is also applicable to the electrosynthesis of chemicals of both organic and inorganic types, such as hypochlorite bleaches and other oxidation products.

Description

Electrolysis device and method for purifying aqueous solutions and synthesizing chemicals

technical field

The present invention relates generally to the purification of aqueous solutions and to the preparation of useful chemical products, and more particularly to electrochemical methods and electrochemical processes for the electro-purification of drinking water, industrial waste water and contaminated groundwater and the electrochemistry of organic and inorganic chemicals in useful products A more efficient, economical and safer electrolysis device for synthesis (electrosynthesis).

Background of the invention

Wastewater is a useful resource in cities and towns with increasing populations and limited water supplies. In addition to reducing the pressure on limited freshwater supplies, wastewater reuse can also improve the quality of streams and lakes by reducing the amount of sewage they receive. Wastewater can be recycled and reused for irrigation of crops and scenic spots, replenishment of groundwater, or for recreational purposes.

Providing potable water is another life necessity. The quality of naturally obtained water varies from region to region and often requires the removal of microorganisms such as bacteria, fungi, spores and other organisms such as Cryptosporidium, salts, heavy metal ions, organics, and combinations of pollutants.

Over the years, various primary, secondary and tertiary treatments have been used for the decontamination of industrial wastewater, the purification of groundwater and the treatment of domestic water supplies to make them safe to drink. The method mainly includes the combination of mechanical and biological methods, such as crushing, sedimentation, sludge digestion, activated sludge filtration, biological oxidation, nitrification, etc. Physical and chemical methods are also widely used, such as flocculation or coagulation of chemical additives, precipitation, filtration, treatment with chlorine, ozone, Fenton's reagent, reverse osmosis, ultraviolet sterilization, etc.

There are also various electrochemical techniques for the decontamination of industrial wastewater and groundwater, including the treatment of domestic water supplies for drinking. Although electrochemical methods are gaining popularity, their role in water and effluent treatment is still relatively small compared to the aforementioned mechanical, biological and chemical methods. In some cases, other technologies have been found to be more economical in terms of initial capital cost and energy consumption. In general, early electrochemical methods were not competitive in terms of initial capital cost and operating cost compared to conventional chlorination, ozonation, coacervation, etc.

Early electrochemical methods required the addition of supporting electrolytes as conductivity modifiers, which not only increased operating costs, but further created issues regarding by-product disposal. In some cases, electrochemical methods are unable to reduce the concentration of pollutants to the level permitted by government regulations, and thus cannot effectively treat the solution. Therefore, this electrochemical method is insufficient to achieve substantially complete mineralization of organic pollutants in a sustained manner, and lacks the ability to sufficiently decolorize industrial wastewater to comply with government regulations.

Despite the drawbacks of earlier electrochemical methods, electrochemistry is still considered as the main technique for the decontamination of aqueous solutions. Accordingly, there is a need for more efficient and safer electrochemical cell structures and methods to more economically treat large volumes of industrial wastewater, discharge streams and contaminated groundwater, including decontamination of domestic water supplies to make them potable. The electrochemical cell structure is also suitable for electrosynthetic chemical products.

Brief description of the invention

The present invention relates to an improved apparatus for the electropurification of aqueous solutions, particularly effluent streams, containing wastewater contaminated with a wide range of chemical and biological contaminants including representative groups from eg organic and some inorganic compounds. Representative possible inorganic pollutants include ammonia, hydrazines, sulfides, sulfites, nitrites, nitrates, phosphites, metal ions, and the like. Organic pollutants include organometallic compounds; dyes from textile mills; carbohydrates, fats, and proteins from food processing plants; discharge streams such as black liquids containing lignin and other pigments from pulp and paper mills; general Types of water pollutants, including pathogenic microorganisms such as bacteria, fungi, molds, spores, cysts, protozoa and other infectious agents such as viruses; oxygen-consuming waste, etc.

While it is not possible to list all possible contaminants that can be successfully treated by the patented process, it is understood that the words "contaminated aqueous electrolyte solution" or variations thereof appearing in this application are intended to cover all possible organic, Inorganic, metal ion or biological pollutants.

The electropurification method and apparatus used in the practice of this invention are particularly noteworthy for their ability to effectively purify virtually any aqueous solution containing one or more organic species and some inorganic species, including concentrations as low as <1 ppm to as high as >300,000 ppm Harmful metal ions and biological pollutants that exist in the concentration range.

In most cases, only electricity is needed to achieve the desired chemical changes in the pollutant composition. The conductivity of tap water is sufficient for improved electrolyzer designs to operate. Thus, it is neither necessary nor necessarily advantageous to add additives to the contaminated aqueous solution to improve the conductivity of the treated solution and to achieve the desired breakdown of the pollutants. Beneficially, in most cases no solid by-products are produced in the electropurification reaction and thus do not pose costly disposal problems. The improved electrochemical process of the present invention can achieve complete or substantially complete decolorization, removal of organic pollutants at a cost competitive with traditional non-electrochemical methods such as chlorination, ozonation and coacervation. Mineralization, and complete destruction of biological pollutants, even in the presence of mixed pollutants, meet or exceed government regulations.

Therefore, the main object of the present invention is to provide an electrolytic cell comprising at least one anode and at least one cathode as electrodes located in an electrolysis device zone. Preferably, the electrodes are located close enough that the gap between the electrodes not only minimizes cell voltage and IR losses, but also enables conductivity without the need for additional supporting electrolytes or current-carrying media. Means are provided for adding the electrolyte solution directly to the electrodes to distribute in the gap between the electrodes. Means are provided for adjusting the residence time of the electrolyte solution in the electrolyser zone. When an electrolyser is used for electro-purification, the electrolyte is left in the electrolyser zone for a period of time sufficient for modification of the contaminants to take place, either directly electrochemically and/or during residence in the cell Chemical modification to convert pollutants into less toxic substances. Additional means are provided to collect the settled electrolyte solution from the electrolyser zone. Obviously, the electrolytic cell of the present invention has an "open structure".

In addition to the electrochemical cell of the present invention, means are further provided for practical and efficient operation, such as direct addition of contaminated aqueous electrolyte solution to the cell by pump means or gravity; Pre-treatment devices such as aeration, pH adjustment, heating, filtration of larger particles; and post-treatment devices such as pH adjustment and cooling, or chlorination to provide residual bactericidal effect in potable water applications . Additionally, the present invention includes in-line monitoring with sensors and microprocessors for automated computer-aided process control, such as pH sensors, UV and visible light, sensors for biological contaminants, temperature, etc.

A further object of the present invention is to provide a system for purifying aqueous solutions comprising:

(i) An electrolytic cell comprising at least one anode and at least one cathode as electrodes located in an electrolyzer zone. The electrodes are located close enough to each other that the gap between the electrodes minimizes cell voltage and IR losses. Also included is a duct member for adding contaminated aqueous electrolyte solution directly to the electrodes of the electrolyzer zone. The electrolytic cell is characterized by an open structure.

(ii) A control valve member for controlling the flow of contaminated aqueous electrolyte solution directly to the electrodes via the delivery tube member of (i) above.

(iii) comprising means for pumping contaminated aqueous electrolyte solution through the delivery tube member, and then

(iv) Including a rectifier element for providing a DC power supply to the electrolyzer.

The purification system also includes sensor components and computerized components for receiving input data from the sensor components and providing output signals to control at least one operating condition selected from the group consisting of current density, contaminated The flow rate of the aqueous solution to the electrolysis cell, the temperature and pH value of the contaminated aqueous electrolyte solution. Optional components include exhaust means for further treatment of electrochemically generated gaseous by-products, means for pretreatment of contaminated aqueous electrolyte solution selected from the group consisting of filtration, pH adjustment and temperature adjustment .

As mentioned above, the novelty of the electrolytic cell according to the invention lies in its "open structure". As described in the specification and claims, "open structure" or variations thereof is defined as an electrochemical cell design suitable for controlling leakage or discharge of the treated or decontaminated aqueous electrolyte solution and gaseous or volatile by-products. The above definition also expresses the dispensation or exclusion of conventional closed electrochemical cells or cell-type cell designs that use conventional indirect means to add electrolyte to the electrodes. An electrochemical cell of the closed flow type, such as usually constructed of several machine or injection molded cell frames, usually joined under pressure into a leak-tight stack, and with gaskets or O-rings to prevent electrolyte Leakage from tank. This type of closed electrochemical cell is generally found in closed plate or frame type electrolyzers. The cell assembly requires very tight fitting tolerances to seal the cell and avoid leakage of electrolyte and gases into the atmosphere. Accordingly, such electrochemical cells have high initial costs, refurbishment costs including replacement costs for damaged cell frames and liners detached from closed plate or frame type cells.

Because the configuration of the electrochemical cell of the present invention is "open" rather than sealed, the leakage of the aqueous electrolyte solution and gaseous by-products can be controlled without the need for a sealed cell design, including gaskets, O-rings with other sealing devices. Instead, the cell components are held in close proximity as desired by various mechanical components such as clamps, bolts, strings, loops or fittings that interact by snapping together. As a result, with the new open cell concept of the present invention, initial electrolyser costs, renewal and maintenance costs may be minimized.

In the open-structure electrolyser of the present invention, electrolyte is added directly to the electrodes of the electrolyser zone from a feeder which is centrally located with respect to the electrode faces, e.g. Flows through very narrow gaps or spaces between electrodes or contacts electrodes. During this time, the pollutants in the aqueous solution are converted directly into less toxic substances in the electrodes and/or via the spontaneous generation of chemical oxidizing or reducing agents such as chlorine, bleach i.e. hypochlorite, hydrogen, oxygen or reactive Oxygen products such as ozone, peroxides such as hydrogen peroxide, hydroxyl radicals, etc., are chemically modified into less toxic substances such as carbon dioxide, sulfate, hydrogen, oxygen and nitrogen. In some cases, depending on the composition of the contaminants in the solution being treated, low concentrations of salts such as sodium chloride, iron salts or other catalytic Salt, may be needed. For example, it can be used to generate some active chlorine to provide a residual concentration of disinfectant in treated water, or to generate ferrous ions to facilitate the production of Fenton's reagent from added or electrochemically generated hydrogen peroxide. Likewise, oxygen or air may be introduced into the feed stream to promote peroxide formation.

Since the electrolyte is usually directly added to the electrode group under positive pressure, gases such as hydrogen and oxygen generated during electrolysis are less likely to accumulate on the electrode surface by forming insulating layers or bubble regions. The shielding effect of the gas on the electrode causes a large current internal resistance, which leads to a high cell voltage and a large power consumption. However, in the present invention, the electrolyte flows directly to the cell, and the dynamic flow of the solution in the gap between the electrodes reduces the gas shielding effect and thus the cell voltage.

Aqueous solution entering the electrolyzer by a pump or gravity feed means cascades over and through the gap between electrodes where applicable, and exits the electrolyser region of the cell due to gravity, and descends into a reservoir for post-processing Treat or discharge, such as into natural waterways. Conversely, any undissolved gases produced by electrolysis are vented upward from the tank to the atmosphere and, if necessary, drawn into a fume collector or fume hood for collection or further treatment.

Although the above-mentioned "open structure" electrochemical electrolyzer with direct feeding preferably does not need conventional electrolyzer shields or tanks, it is described in detail later, and the "open structure" that appears in the description and claims is in addition to the aforementioned Outside the definition, includes the design of the electrochemical cell in which the directly added electrodes are located in an open cell or in the interior region of an open cell enclosure. A representative example of an open cell electrochemical cell is disclosed in US Patent No. 4,179,347 (to Krause et al.) for use in a continuous system for disinfection of wastewater streams. The electrolytic cell has an open top, a bottom wall, side walls and electrodes spaced apart from each other inside the cell. The contaminated aqueous solution is not added directly to the electrodes located in the tank, but as disclosed by Krause et al., the electrolyte is initially added to one of the first terminals of the tank, where internal baffles create a flow in the wastewater that pushes the wastewater upwards Cycle down through parallel electrodes and cycle between electrodes. Thus, in the open electrolyzer of Krause et al., the electrolyte contacts the electrodes indirectly through a flooding effect, essentially by placing the electrodes in the lower region of the cell where the aqueous solution resides, unlike The present invention delivers electrolyte directly to the electrode stack, where the electrolyte is forced under pressure through the gap between adjacent anodes and cathodes. This passive flooding effect is insufficient to achieve the mass transfer conditions required for effective disruption, especially when contaminants are present in low concentrations. Thus, the gaseous by-products of the electrolysis reaction can and often form a layer of gas bubbles on the electrode surface. It results in higher cell voltage and higher energy consumption due to higher internal resistance.

Thus, for the purposes of the present invention, "open structure" as it appears in the specification and claims is intended to include electrochemical cells of the open tank type in which the electrode set is located inside an open tank/shroud, and Means are included to add contaminated aqueous solution directly to the electrodes. In the case of direct addition, the shield does not serve as a reservoir for contaminated aqueous solution which would otherwise passively engage the electrode indirectly by a flooding effect.

For the purposes of this invention, it is understood that "open construction" also includes protective devices that facilitate proximity to electrochemical cells and purification systems, such as splash guards, shields, Boards and cages. Therefore, for example, setting the electrolytic cell and the purification system of the present invention in a small room is also included within the meaning of "open structure" appearing in the specification and claims.

Another type of electrochemical cell design is disclosed by Beck et al. in US Patent No. 4,048,047. The cell design of Beck et al. includes a bipolar set of annular electrode plates separated by separators to provide electrode gaps from 0.05 to 2 mm. Liquid electrolyte is added directly to the electrode plates via a line that enters the central opening of the electrode stack and then out, allowing the electrolyte to flow down the exterior of the electrode stack. However, the electrode assembly is housed in an associated closed shroud with a cover to avoid loss of gaseous reactants, vapors or reaction products. Therefore, the closed structure of the electrolyzer of Beck et al. does not meet the criteria of the "open structure" electrolyzer of the present invention.

While it has been pointed out that the present invention's improved and highly economical "open architecture" of electrochemical cell design is based on the elimination of traditional closed cell designs, including plate and frame type cells and conventional cell type cells, and Conventional electrolyzer designs of the partially open structure type, whether they are batch or continuous, it is understood that the "open structure" that appears in the specification and claims also refers An electrochemical electrolyzer that is improved by various inserts, barriers, separators, deflectors, etc. on its edges. This modification has the effect of changing the circulation and direction of the electrolyte, and increasing the residence, residence time, and thus affecting the residence time and the rate at which the electrolyte is drained from the cell. Nevertheless, the partially open modified electrochemical cell does fall within the meaning of "open structure" when the electrodes themselves are still substantially accessible. A representative modified electrochemical cell whose electrodes are still substantially similar and covered within the meaning of "open structure" in the specification and in the so-called "Swiss roll cell" design, wherein For example, an "open Swiss roll electrolyzer" is formed by removing the tubular closed casing of the electrodes that overlap each other and are rolled up in a concentric manner.

A further object of the present invention is to provide a more efficient electrochemical cell design that can effectively treat a wide range of chemical and biological pollutants at different concentrations (from a few ppm to thousands of ppm) and in aqueous media, It is economically competitive with conventional water purification systems in terms of capital cost and power consumption. The electrochemical system and method of the present invention have significantly improved economics, making it suitable to treat large volumes of industrial wastewater from production facilities such as chemical factories, textile mills, paper mills, food processing plants, etc. via a continuous process.

The lower cell voltage and higher current density are achieved with a highly economical open structure, especially when the structure is a monopolar electrochemical cell, which is equipped with electrodes with a narrow capillary electrode gap. In general, the gap width between the electrodes is narrow enough to achieve electrical conductivity without the addition of additional supporting electrolytes or current-carrying media in the contaminated aqueous solution. Thus, the need to add a supporting electrolyte as a current-carrying medium in the contaminated aqueous electrolyte solution can be avoided.

Thus, it is a further object of the present invention to provide an improved, more economical and safer continuous, semi-continuous or batch process for the electropurification of contaminated aqueous solutions in the following steps:

(i) An electrolysis cell is provided comprising at least one anode and at least one cathode as electrodes located in an electrolysis device zone. The electrodes are located close enough to each other to provide an electrode gap that minimizes loss of cell voltage and IR. Means are provided for adding the contaminated aqueous solution directly to the electrodes of the electrolyzer zone. Means are provided for adjusting the residence time of the electrolyte solution in the electrolyser zone during electrolysis to modify the contaminants. The electrolytic cell is characterized by the aforementioned "open structure";

(ii) adding contaminated aqueous electrolyte solution directly to the electrolyzer area of the electrolyzer, and

(iii) Applying a voltage across the electrodes of the electrolytic cell to modify and preferably destroy contaminants in the aqueous electrolyte solution.

It will be appreciated that the method generally includes the step of recovering a purified electrolyte solution from the electrolytic cell. However, the present invention contemplates sending the purified aqueous solution directly, for example, into a watershed, or optionally to other post-processing stations.

As mentioned above, the method is carried out in an electrolytic cell with an open structure, and the battery can be of monopolar or bipolar structure. Because of the open structure, as described, the present invention can be designed as a monopolar structure. This is particularly advantageous since higher current densities will be required when the electrolytic conductivity of the contaminated aqueous solution is rather low and at the same time a low cell voltage is to be maintained. Likewise, the improved electrochemical cell of the present invention can have a bipolar configuration, especially for large installations to reduce bus and rectifier costs.

Typically, in a monopolar open cell design, the electrodes are electrically connected. Whereas in a bipolar configuration it is electrically connected to the terminal electrodes. However, increasing the surface area of electrodes is required in many applications, especially from laboratory-scale electrochemical cells to semi-industrial scale and finally to industrial-scale open cells. It would be advantageous if a more efficient electrolyser design for carrying out the process of the invention could be achieved in the expansion of the electrolyser and further reduce capital and operating costs.

It is therefore another main object of the present invention to provide other and more economical embodiments of the open cell concept of the present invention, wherein the surfaces of the porous electrodes are adjacent to each other and arranged in a vertical plane or horizontally to each other in a group overlapping. Porous electrodes, usually meshes or screens, are in electrical contact with each other, and each electrode set requires only a single supply electrode to introduce voltage thereto. Thus, by arranging the electrodes in this representative form, the effective electrode surface area will be significantly increased without requiring an increase in the number of external electrical contacts to the power supply as would otherwise be the case. By layering the electrodes, the connection cost can be reduced, and the electrode purchase cost can also be saved. Other benefits include improved efficiency of operation with an open cell configuration, lower power consumption and lower operating costs as a result of lower cell voltage.

Thus, the present invention develops an embodiment of an "open electrolyzer" structure, wherein the electrolyzer comprises at least one anode and at least one cathode as electrodes in an electrolyzer area. At least one electrode includes a plurality of conductive porous elements adjacent to each other and in electrical contact with each other. Means are provided for adding an aqueous electrolyte solution directly to the electrodes of the electrolyzer zone, and for adjusting the residence time of the electrolyte solution in the electrolyzer zone.

In addition, electrodes comprising several conductive porous elements may be combined with a solid, non-porous conductive electrode element.

Also included is a method for electropurifying a contaminated aqueous solution comprising the steps of:

(i) Provide an electrolytic cell of open structure comprising at least one anode and at least one cathode as electrodes in an electrolyzer zone. At least one electrode comprises several conductive porous elements, such as meshes or screens, adjacent to each other and in electrical contact with each other. Means are provided for adding a contaminated aqueous electrolyte solution directly to the electrodes of the electrolyzer zone. Means are also provided for adjusting the residence time of the aqueous electrolyte solution in the electrolyzer zone to modify contaminants therein;

(ii) adding the contaminated aqueous electrolyte solution to the electrolytic cell of (i), and

(iii) Applying a voltage across the electrodes of the electrolytic cell to modify the contaminants in the electrolyte of the aqueous electrolyte solution.

The improved electropurification method of the present invention also includes the treatment of aqueous solutions contaminated with metal ions. Typically, it is a toxic substance from plating tank discharge water, metal leachates, biocides and paints, and can be sequestered by a complexing, surfactant or reducing agent. The electro-purification method of the present invention can destroy the complexing agent, surfactant or reducing agent to release harmful metals for further processing in the electrolytic cell, or optionally, for example, transfer to a metal recovery electrolyzer, for removal from solution. Electrodeposit metal.

Although the primary use of the electrolytic cells disclosed herein is the electropurification of contaminated solutions, the "open" configuration of the present invention can be used in other practical applications. Representative examples include electrochemical synthesis of inorganic and organic compounds, such as iodate and periodate, chlorine dioxide, persulfate, and electrolysis via Kolbe carboxylic acid or electrolysis of activated olefins. Hydrogenation of the dimer of dimerization, electrolysis of water to form hydrogen and oxygen, etc.

Therefore, another main object of the present invention is to provide an electrosynthetic method to produce useful products, the steps of which method include:

(i) An electrolytic cell having an open structure is provided, wherein the electrolytic cell is provided with at least one anode and at least one cathode as electrodes located in an electrolyzer region. At least one electrode comprises several conductive porous elements, such as meshes or screens, adjacent to each other and in electrical contact with each other. Means are provided for adding an electrolytic solution directly to the electrodes of the electrolyzer zone. means are also provided for adjusting the residence time of the electrolyte solution in the electrolyzer zone;

(ii) Adding to the electrolytic cell of (i) an electrolyte comprising an electroactive substrate such as a solution of inorganic salts, such as an aqueous solution of alkali metals in the manufacture of bleaches, iodic acid in the manufacture of periodates salt, an aqueous acid solution, etc.; and

(iii) Applying a voltage across the electrodes of the electrolytic cell to electrolyze the electrolyte solution to form a useful chemical product.

Embodiments of the invention include methods for the electrosynthesis of a useful product wherein the electrolytic cell is provided with a porous separator or permselective membrane.

Description of drawings

For a further understanding of the invention and its characteristics, reference should be made to the accompanying drawings in which:

Figure 1 is a side view showing a first embodiment of the direct feed, open structure, controlled leakage electrochemical cell of the present invention, wherein the electrodes are positioned above a water collection vessel in a horizontal orientation;

Figure 2 is a side view of the electrochemical cell of Figure 1 with its electrodes vertically oriented;

Figure 3 is a side view showing a second embodiment of the direct-fed, open-construction, controlled-leakage electrochemical cell of the present invention, wherein the electrodes are located inside an open cell hood;

Fig. 4 is the sectional view of the electrode electrolyzer group of Fig. 1;

Figure 5 is a side view of an electrode group connected in a monopolar structure according to the present invention;

6 is a side view of an electrode group connected in a bipolar structure according to the present invention;

Figure 7 is a front view of an electrode group spaced apart by separators;

Figure 8 is a side view of an open electrochemical cell with a set of porous electrodes connected in a monopolar configuration;

Figure 9 is a side view of an open electrochemical cell having a set of porous electrodes connected in a bipolar configuration; and

Fig. 10 is a graph illustrating the results of electropurification for decontaminating phenol aqueous solution according to the method of the present invention, as shown in the examples.

Description of preferred embodiments

First, FIG. 1 shows an electrochemical cell 10 for purifying the aforementioned contaminated aqueous solution, which is represented by contaminated water 12 passing through inlet 22 . Contaminated water 12 is treated in electrolyser zone 14 of electrolyzer 10, which as shown is a completely open structure allowing gaseous by-products of the electrolysis reaction, such as oxygen and hydrogen 16, to be released to the atmosphere. In some cases, it is desirable to capture some of the potentially harmful gases produced during the electrolysis reaction to avoid venting to the atmosphere. Chlorine may be produced at the anode, for example, during electrolysis of an aqueous discharge stream containing brine or seawater. The gas may be recovered, for example, by a conventionally designed vacuum powered vent (not shown) adjacent to the electrochemical cell 10 .

The electrolyzer zone 14 includes an electrode set 17 shown in a horizontal orientation in FIGS. 1 and 4 , and includes at least one cathode 18 and at least one anode 20 . For example, the anode 20 may serve as a terminal plate 21 for supporting the combination of electrodes, separators and separators to form an assembled electrode assembly 17 . A non-conductive electrode separator 23 located between the electrodes provides the required inter-electrode gap or space between adjacent anodes and cathodes. Although Figures 1 and 4 only show a central cathode with an anode on the opposite side of the cathode 18, it will be appreciated that the electrode group may be formed from a number of alternating anodes, separators, cathodes, etc., with bolt members 25 passing through the group and Hold the components in a structurally stable assembly with termination plates.

The terminal plates, electrodes and separators may have a generally rectangular geometry. However, any other possible geometry and size is within the scope of the present invention, including the limited examples of square, circular or ring configurations. The contaminated aqueous electrolyte solution is added directly to the electrodes in the electrolyser zone 14 via supply line 22 . The supply line 22 is shown in a central position relative to the anode/termination plate 21 . It may be a solid and planar electrode, preferably a mesh/sieve type of material. This causes the aqueous electrolyte solution entering the electrode group to directly contact the electrodes and to flow radially across each electrode surface within the electrode group towards its edges. In addition, the incoming solution flows generally axially, or normally to the longitudinal axis of the electrode plane, so that the contaminated aqueous solution cascades over and through the electrode set in a fountain-like effect, while maximizing contact with the electrodes in the process. contact with the electrode surface. Purified water 24 , free or substantially free of contaminants, exiting electrolyser zone 14 may be collected in an open tank 26 or funneled into a discharge line (not shown) for discharge to a natural watershed or the like.

It will be appreciated that the feed of the contaminated aqueous solution, which is added directly to the electrolyser zone, need not be centrally located relative to the electrode set as shown in Figures 1-4. Other direct feed paths include inverting the feed point so that the contaminated aqueous solution is added from the bottom of the electrode stack, or added at an oblique or obtuse angle relative to the plane of the electrodes. Additionally, the entry point for the direct feed can be axial to the planar surface edge of the electrodes, wherein the contaminated solution is fed to the peripheral edge of the electrode set.

A convenient means for regulating the residence time of the contaminated aqueous solution in the electrolyzer zone 14 and for controlling leakage of the decontaminated and purified water 24 therefrom may be via valve 28 and/or conventional design pump components (not shown). The flow rate of contaminated water directly into the electrode stack and decontaminated water out of the stack can be adjusted manually or via an automated flow control valve 28 of standard design. The flow rate (liters per minute) is adjusted to be sufficient to effectively destroy contaminants as the treated solution exits the electrolyser zone. Those of ordinary skill in the art, in light of this disclosure, will appreciate that the performance of the electrochemical cell of the present invention can be optimized in other ways, such as increasing the path of the solution in the electrolyser zone. For example, the addition of baffles can increase the residence time of the solution in the electrolyzer zone. Other approaches include enlarging the surface area of the electrodes to reduce the residence time in the electrolysis zone. In fact, electrochemists skilled in the art will also understand that the performance of the electrolyzer can be increased at higher current densities.

Because of the cell geometry and the ability to conveniently use monopolar and bipolar configurations, virtually any electrode material can be used, including metals in the form of plates, meshes, foams, or other substances such as graphite, glassy carbon , Network glassy carbon and granular carbon. This also includes compositions of electrode materials such as bilayer components comprising two metal layers separated by a suitable insulating or conducting material.

Representative examples suitable as anodes include the commonly known rare metal anodes, size-invariant anodes, carbon, reticulated carbon, and graphite-containing anodes, doped diamond anodes, anodes containing substoichiometric titanium oxide , and an anode containing lead oxide. More specific representative examples include platinum-coated titanium rare metal anodes, anodes under the trademark DSA- _O , and other anodes, such as the high surface area types available from Electrosynthesis, Inc., Lancaster, NY, USA, such as Felt, foam, screen, etc. Other anode materials include titanium-based platinum/iridium, titanium ruthenium oxide, titanium iridium oxide, titanium nail oxide, silver metal oxide, titanium ruthenium oxide, titanium tin oxide, titanium ruthenium oxide, nickel Nickel(III) oxide, gold, substoichiometric titanium oxide, and especially the so-called Magneli phase titanium oxide having the formula _TiOx where X is from about 1.67 to about 1.9. A preferred substoichiometric titanium oxide is Ti ₄ O ₇ . Magneli phase titanium oxide and methods for its preparation are disclosed in US Pat. No. 4,422,917 (to Hayfield), which is incorporated herein by reference. It is also commercially available under the trademark Ebonex(R). When electrocatalytic metal oxides such as PbO ₂ , RuO ₂ , IrO ₂ , SnO ₂ , Ag ₂ O, Ti ₄ O ₇ and others are used as anodes, it is found that if these oxides are doped with various cations or anions, The conductivity of the inventive electrocatalytic oxidation, stability or decontamination can be further enhanced. Selection of a suitable anode material will be based on considerations such as cost, stability of the anode material in the treatment solution, and its electrocatalytic properties for achieving high efficiency.

Suitable cathode materials include metals such as lead, silver, iron, nickel, copper, platinum, zinc, tin, and the like, as well as carbon, graphite, Ebonex, various alloys, and the like. Gas diffusion electrodes are also used in the process of the invention. As such, it can act as a cathode in converting oxygen or air into an effective amount of peroxide, to reduce hydrogen evolution and/or to reduce cell voltage. The electrode material, whether anode or cathode, regardless of its surface area, can be coated with an electrocatalyst. When toxic or hazardous substances are present in low concentrations in aqueous electrolytes, electrodes with large surface areas, such as expanded metal screens, metallic or graphite beads, carbon felt, or networked glassy carbon, are particularly suitable for achieving efficient destruction of such substances. class of substances.

Specific anode and cathode materials are selected based on cost, stability, and electrocatalytic properties. For example, one of ordinary skill in the art of electrochemistry will understand when it is necessary to convert chloride to chlorine; to convert water to ozone, hydroxyl radicals, or other reactive oxygen products; When converting oxygen or air to hydrogen peroxide or hydroxyl radicals via electrochemically generated Fenton's reagent; and catalytic reduction of nitrates to nitrogen, or catalytic reduction of organohalogen compounds Which electrode material should be selected when it is transformed into less toxic halide ions or organic moieties.

The choice of catalytic anode and cathode materials is particularly important when dealing with aqueous solutions of complex mixtures containing pollutants, where the electrode species can be selected for the disruptive action of the pollutant pairing. For example, a water stream contaminated with organic matter, microorganisms, and nitrate contaminants can be used in the same electrochemical cell using an anode that produces reactive oxygen products, such as platinum on niobium or Ebonex, While processing at the same time to destroy microorganisms and oxidize organic matter. In addition, the same cell can also be equipped with a lead or other electrocatalytic cathode substance to destroy nitrate.

As previously mentioned, the non-conductive electrode separator 23 provides the required inter-electrode gap or space between adjacent anodes and cathodes. The separator 23 is a non-conductive insulating porous mesh made of a polymer material such as polyolefin such as polypropylene and polyethylene, and its thickness determines the width of the gap between the electrodes. In addition, it allows the use of ionic polymer separators, which can effectively increase the ionic conductivity of the electrolytic cell, allowing further reductions in cell voltage and operating costs. Appropriately sized ion exchange resins, such as cation and anion resin spheres, are fixed in the gap between the electrodes.

For most applications, the gap between the electrodes ranges from nearly no gap to avoid shorting the electrodes, to about 2 mm. In particular, it is preferred that the extremely small capillary dimensions have a gap of less than 1 mm, from 0.1 to <1 mm. The extremely small gap between the electrodes allows current to pass through the relatively non-conductive medium. This is the case, for example, when water is contaminated with organic compounds. Thus, contaminants in solution can be destroyed by the present invention without adding any carrier inorganic salts to increase the ionic conductivity in the aqueous medium. Furthermore, the extremely narrow inter-electrode gap provides the important advantage of lower cell voltage, which in turn reduces power consumption and lowers operating costs. Thus, the combination of the present invention's open-structure electrochemical cell with extremely narrow inter-electrode gaps provides lower initial capital costs as well as lower operating costs. This feature is particularly important for large-scale applications, as in the case of purification of drinking water and waste water according to the claimed method.

FIG. 2 shows another embodiment of the electrochemical cell of the present invention, wherein the electrolyzer area 30 is an open structure. Electrolyte 32 is added directly to vertically oriented electrode set 34 . The results show that the treated aqueous solution 36 is mainly discharged from the top and bottom peripheral edges of the electrode assembly 34 . It can further vary depending on the use of the baffles, for example to control the residence time of the solution being treated. The purified solution is collected in vessel 38 below electrolyser zone 30 .

Figure 3 shows a third embodiment of the invention in which the electrolyzer zone 40 includes an electrode assembly 42 as described above within an open shroud/tank 44 . A shroud 44 is provided at the top opening to allow the gaseous by-products of the electrolysis reaction, such as hydrogen and oxygen, either to vent to the atmosphere or to be collected by means of a suitable device such as a fume hood (not shown). Contaminated aqueous electrolyte solution 46 is added directly to electrode set 42 located in open shroud 44, unlike an electrolytic cell in which the electrodes receive the electrolyte indirectly by being submerged in the solution sent to the cell. solution. Purified water 48 cascading downward by gravity is collected at the bottom inside the shroud 44 and is drained.

An important advantage of the open-structure electrochemical cell of the present invention is its ability to be adapted for either monopolar or bipolar configurations. In this regard, Figure 5 shows a monopolar open structure electrochemical cell. In the monopolar cell of Figure 5, the anodes 52, 54 and 56 each require an electrical connector for power, in this case via a bus 58 as a common "outgoing" supply line. Similarly, cathodes 60 and 62 each require an electrical connector, which is shown via a common bus 64 . The monopolar cell design is characterized in that both sides of each electrode are active and have the same polarity.

Because water purification for urban areas, generally large-scale applications, has to achieve the lowest possible cell voltage in order to reduce power consumption. The combination of open structure, monopolar electrolyzer design and extremely narrow gap between electrodes of the present invention not only has lower initial capital due to lower internal resistance, lower cell voltage and higher current density The cost advantage also has lower operating costs. As with some embodiments of the present invention, this combination is particularly advantageous when treating contaminated aqueous media with relatively low conductivity, such as aqueous solutions contaminated with non-polar organic solvents, without the addition of inorganic salts as a carrier medium.

The present open structure, unipolar, controlled leakage electrochemical cell with extremely narrow inter-electrode gaps is very unique to the cell disclosed in US Patent No. 4,048,047 to Beck et al. The closed electrochemical cell of Beck et al. makes the unipolar connection with high current density realized by the external electrical contact of each electrode very difficult and expensive. In contrast, the open structure of the electrochemical cell of the present invention facilitates electrical connections to individual electrodes, whether the cell is of monopolar or bipolar design. Thus, the closed bipolar electrochemical cell of Beck et al. would not be economical and comparable to the improved electrochemical cell of the present invention or other non-electrochemical techniques used in large volume water purification processes. cost competitiveness.

As mentioned above, the electrochemical electrolyzer of the present invention having an open structure with a very narrow gap between capillary electrodes and controlling leakage can be applied to a bipolar structure. FIG. 6 illustrates an open structure bipolar electrolyzer according to the present invention which requires only "outside" electrical contacts 72 and 74 via two terminal electrodes/terminal plates 76 and 78 . Each of the internal electrodes 80, 82 and 84 of the bipolar electrodes has a different polarity on opposite sides. Although the bipolar electrodes are quite economical by effectively using the same current in each cell of the electrode set, an important aspect of the present invention involves processing a solution by passing an electric current through a relatively non-conductive medium with extremely narrow inter-electrode gaps. . That is, the contaminated aqueous solution may have a relatively low conductivity, approximately equivalent to that of tap water. To effectively handle this dissolution, it is necessary to operate at higher current densities. The monopolar cell structure of the present invention can operate at the stated low cell voltages and high current densities. Although not described in detail, it is understood that the electrolyzer of the present invention uses standard power sources, including DC power, AC power, pulse power and battery power.

The present invention also relates to an open structure electrochemical cell having a distributor member for contaminated aqueous electrolyte solution, such as a length of tube 81 having several openings and holes, or for feeding from contaminated aqueous electrolyte. The feed inlet extends through a feed tube to the depth of the electrode array of the electrolyzer zone. It can promote a more uniform flow of the solution to the electrode element. This kind of porous tube of metal or plastic material with sufficient porosity, diameter and length is especially suitable for electrode groups containing many electrode elements, and can be applied to open structure monopolar, bipolar and such as swiss roll electrolyzers . In the case of a deep cell bank with electrode elements, each electrode element having a relatively large surface area, more than one porous feed tube may be provided with a manifold integrated with the feed inlet conduit.

The open structure, bipolar, controlled leakage electrochemical cell of the present invention can be most effectively used to purify aqueous solutions with higher ion conductivity than previously described, enabling more economical operation at lower current densities. In each case, the electrochemical cell of the present invention facilitates the electrical connection of the cell, whether it is of monopolar or bipolar design.

High volume applications like water purification preferably require low capital and operating costs to be economically attractive. The inventors have discovered that capital costs can be substantially reduced by reducing the need for delicate machine components, liners, expensive membranes and electrolyzer separators. Low operating costs can be achieved by eliminating the cell membrane and separator, ie, undivided electrochemical cells, resulting in narrow interelectrode gaps and lower IR, resulting in lower cell voltages. However, the smaller inter-electrode gap also enables the electrolytic cell of the present invention to operate with various electrodes, insulator substances, etc., eg in an organic medium containing a low concentration of supporting electrolyte. The open structure of the present invention is suitable for a variety of applications, but the use of cell dividers, such as membranes or cell separators, will form the anolyte and catholyte compartments. Embodiments of the process applicable to the electrochemical cell of the present invention include mediated reactions in electrochemical synthesis where the purpose of the membrane or cell separator is to prevent the reduction of the product produced at the anode and/or the generation at the cathode The product is anodized.

FIG. 7 is a representative embodiment of an open structure electrochemical cell 90 having anode/terminal plates 92 and 94 and a central cathode 96 with cation exchange membranes 98 and 100 between the electrodes. Membranes 98 and 100 prevent mixing of the anolyte and catholyte in the cell, although the solutions are allowed to flow through an opening 102 located in the center of the membrane.

Embodiments of electrochemical cells using a membrane or separator, preferably equipped with ion exchange membranes, although separators of the porous membrane type can of course also be used. Variety of inert materials available commercially based on microporous films of polyethylene, polypropylene, polyvinylidene-difluoride, polyvinyl chloride, polytetrafluoroethylene (PTFE), polymer-asbestos blends, etc. material, suitable as a porous diaphragm or separator.

Suitable permselective membranes, both cationic and anionic types, are available from a number of manufacturers and suppliers, including such companies as RAI Research, Inc. of Hauppauge, NY, USA under the trademark Rsipore, E.I. DuPont, Tokuyama Soda, Asahi Glass et al. In general, fluorinated membranes are best for their overall stability. One particularly suitable type of selectively permeable ion exchange membrane is a perfluorosulfonic acid membrane, such as available from E.I. DuPont Company under the Nafion(R) trademark. The invention also includes membranes and electrodes formed as solid polymer electrolyte composites. That is, at least one electrode, the anode or the cathode or both, is combined with the ion exchange membrane to form an integral assembly.

Although the foregoing embodiments of the present invention refer to electrode groups, such as elements 17 and 34 in FIGS. 1 and 2, respectively, the electrode groups include individual, single anodes and single cathode assembly. FIG. 4 illustrates in cross-section a representative electrode set comprising a cathode 18 consisting of a single planar screen element with its own circumscribing electrical contact 19 . Non-conductive porous separators 23 on each side of the cathode 18 provide the required interelectrode spacing to separate the cathode element from the adjacent terminal anode 20 . Although FIG. 4 shows an electrode pack with a single cathode screen positioned between terminal anodes 20, it will be appreciated that larger throughput commercial or semi-commercial pilot scale electrolyzers of the present invention will typically have Group of electrolytic cells with alternating anodes and cathodes, each electrode having an external electrical contact in monopolar configuration.

However, the scaled-up version of the electrolytic cell of the present invention requires a larger electrode surface area, which can be achieved in a more economical manner by stacking several individual porous electrode elements as shown in FIGS. 8 and 9 . Multi-electrode elements comprising conductive porous elements, such as meshes or screens, are adjacent to each other and in electrical contact with each other in a monopolar (Fig. 8) or bipolar (Fig. 9) open cell configuration.

The anode or cathode, or both, of the open electrolyzer embodiments may be of multi-electrode element design. That is, an anode group comprising multiple electrode elements is secured together in electrical contact and may be adjacent to a cathode comprising a single electrode element, and vice versa. Best illustrated in Figure 8, it comprises a single pole open electrolytic cell 104 secured between end plates 105 having a plurality of porous anode elements 106 positioned between a single cathode element 108, which is shown as porous Sexual cathode, but it can also be a non-porous plate electrode. The anode 106 is separated from the cathode 108 by a porous non-conductive separator 107 . Advantageously, the anode set 106 requires only a single "supply" electrode 110 to deliver voltage on either side to other electrode elements in the same set that are in contact with it. By stacking the electrode elements together in this way, the effective electrode surface can be significantly increased without requiring an increase in the number of external electrical contacts 112 to the power source 113 as would otherwise be the case. This not only reduces the cost of the external circuit connector and the cost of the electrode, but also improves the operating efficiency, forms a lower cell voltage and lower power consumption, and reduces the operating cost.

The conductive porous element of the electrode can be made, for example, of metal or carbon, and can be a perforated metal plate, welded wire cloth, woven wire cloth, expanded metal plate, carbon felt, woven carbon cloth, reticulated glassy carbon including such as with The spongy nature of the nickel foam is formed from the metal foam. Representative examples of commercially available perforated metal plates are mild steel plates, and microetched 316 type stainless steel plates with a uniform and appropriately sized hole pattern. Welded wire cloth includes Type 304 stainless steel cloth and stainless steel knitted wire mesh. Wire cloth is a material formed by weaving or welding wires and is available in a variety of mesh sizes. Also available in Type 304 stainless steel grade. Expanded metal sheets include slotted and expanded sheets. The board/sheet is lightweight yet extremely strong due to its equi-open diamond framing pattern. It is generally made of carbon steel and type 304 stainless steel.

The present invention includes the combination of different porous materials as electrode elements in a single electrolytic cell to achieve, for example, a combination of oxidation/reduction effects. The conductive porous element of the electrode can have a pore density of from 1 to about 500 pores per linear inch. The conductive porous element may also have an open area of from about 10 to 90%. Some elements, such as foam materials, may have a porosity of from 1 to about 1000 cells per linear inch, and a density of from 5 to about 85%. The electrode elements can simply be stacked in close electrical contact, or welded together and as needed to the supply electrodes to ensure electrical connection through all components of the set.

Figure 9 shows an open cell design 114 similar to Figure 8, but of a bipolar configuration, all of the intermediate electrode sets 116 are shown having several porous electrode elements. Individual elements of each electrode set are in electrical contact with other elements of the same set. Power is sent to the electrolysis cell via terminal plate anode 118 . The electrode groups 116 are separated from each other by a porous separator 120 .

With or without "powered" electrodes, the optimal number of electrode elements that can be used will be a function of several variables including the thickness of the porous electrode elements, the conductivity of the solution being treated and the overall optimum cell design. The number of electrode elements may be 1 to 100, and more specifically 1 to 10 electrode elements, except for the supply electrodes ( FIG. 8 ). Provided that the supply electrode is stable and conductive under electrolytic conditions, the supply electrode can be produced from the same or different material than the individual electrode elements.

During the purification of solutions, the invention provides for the treatment of low conductivity media. However, it may be necessary to add very low concentrations of inert soluble salts, such as alkali metal salts such as sodium and potassium sulfates, chlorides, phosphates, and the like. Stable quaternary ammonium salts may also be used. As mentioned above, ion exchange resin balls of appropriate size can be placed in the space between the electrodes to increase the conductivity. It can further reduce cell voltage and overall operating cost.

The temperature of the contaminated solution entering the electrolytic cell can range from near freezing to near boiling, and more specifically about 40° to 90°C. Higher temperatures favor lower cell voltages and increased contaminant destruction rates. Higher temperatures can be achieved, if desired, by preheating the incoming solution, heating electrodes, or via IR heating in cells, especially when the solution has low conductivity, such as in the case of purified drinking water. By suitably adjusting the cell voltage and residence time in the cell, favorable temperatures in the above ranges can be achieved.

Undivided cells, which are the preferred embodiment of the present invention for purifying contaminated aqueous solutions, produce a variety of useful anodic and cathodic products during electrolysis that aid in the chemical destruction of contaminants and the aqueous solution of purification. Such products include oxygen, ozone, hydrogen peroxide, hydroxyl radicals, and reactive oxygen products. Although also suitable for use in the process, less preferred products include chlorine and hypochlorite (bleach) produced via electrolysis of brine or seawater. While not wishing to be bound by any particular mechanism of action, for successful decontamination, decolorization and sterilization of aqueous solutions contaminated with toxic organic substances and microorganisms, several of the foregoing methods may be performed simultaneously. These include, but are not limited to, direct oxidation of pollutants at the anode, destruction of pollutants by direct reduction at the cathode, oxidation of the feed stream by oxygen microbubbles generated at the anode, oxidation of the feed stream by microbubbles of oxygen and hydrogen Volatile removal of feed streams, IR heating in cells, aeration of water stream exiting the open cell, etc.

The open electrolyzer structure of the present invention using the method described above can successfully destroy or remove various compounds, microorganisms and other harmful substances, such as the aforementioned metal ions. Representative examples include aliphatic alcohols, phenols, nitrates, or halogenated aromatic compounds, among others. It can also achieve color reduction or complete decolorization, as well as disinfection, including the destruction of viruses.

There are a variety of metal salts in aqueous solutions, including toxic metals in the form of ions from electrowinning tank discharge water, metal leachates, biocides and coatings, which are difficult to remove by ion exchange or traditional chemical or electrochemical methods Remove or recycle. These metals include rare metals such as platinum, silver, and gold, and non-rare metals such as copper, nickel, cobalt, and tin. Government regulations will become stricter regarding the maximum allowable concentrations of these metals that can be discharged into sewers. This soluble metal solution is often difficult to handle because of the possible presence of other constituents, typically complexing agents, surfactants, reducing agents, and the like.

Accordingly, the present invention also includes the electropurification of aqueous solutions contaminated with harmful metal ions by using the aforementioned methods in the open electrolyzer disclosed herein. It includes the decontamination of the solution by metal reduction at the cathode of an open electrolytic cell, and the treatment of metal ions from electroplating cell discharge water, metal leachate, biocidal agents, paints and other contaminated industrial aqueous solutions , wherein the metal is chelated by various complexing agents, surfactants or reducing agents. Solution constituents, including complexing agents, are initially destroyed electrochemically to greatly facilitate metal recovery/removal from the solution. Representative complexing agents may include cyanides, ferricyanides, thiosulfates, imines, hydroxycarboxylic acids such as tartaric acid, citric acid and lactic acid, and the like. The method effectively releases the ionized metal for reduction or recovery/removal in the electrolytic cell. Optionally, the partially treated aqueous solution can be further treated outside the open cell by methods such as ion exchange, precipitation with bases, electrochemical electrolysis for metal recovery such as Rebocell ^™ manufactured by Renovare International Electrolysis in the tank. The latter approach facilitates electrodeposition of the metal on a cathode with a large surface area.

The following specific examples illustrate various embodiments of the invention; however, they are given by way of illustration only and are not intended to be limiting in their entirety.

Example I

A monopolar electrochemical cell with an open structure was set up with an electrode assembly comprising 316 stainless steel end plates with a diameter of 12.065 cm and a thickness of 0.95 cm. A central cathode consisting of 316 stainless steel mesh with 7.8 x 7.8 openings/linear centimeter, 0.046 cm wire diameter, 0.081 cm opening width, and 41% open area was also incorporated into the electrode set. The anode consisted of two platinized niobium electrodes manufactured by Blake Vincent Metals, Rhode Island, USA. An anode electrodeposited on both sides of the niobium substrate, having a thickness of 635 microns, was drawn into a mesh having a thickness of about 0.51 cm and a diamond-shaped gap of 0.159 cm. Separators between adjacent electrodes were fabricated from polyethylene mesh with 8.27 x 8.27 openings/linear centimeter, 0.0398 cm wire diameter, 0.084 cm opening width, and 46% open area at Cree, Ohio, USA Supplied by McMaster-Carr of Forlan. The gap between the electrodes is about 0.04 cm, which is determined by the thickness of the polyethylene mesh. The schematic diagram of the electrochemical cell corresponds to Figure 1, except that the fume hood is omitted. The aqueous solution was recirculated between the glass collection tank and the electrolytic tank by means of an AC-3C-MD March centrifugal pump with a flow rate of approximately 1 cm/min. A Sorensen DCR 60-45B power supply was used to generate the voltage drop required for the electrolyzer.

A test solution was prepared containing 1 gram of phenol in 1 liter of tap water. The solution was circulated in the battery and a constant current of 25 amps was applied. After about 2-3 minutes of treatment, the initially clear solution turned red, possibly indicating the presence of benzoquinone-type intermediates. The cell voltage, initially at 35 volts, dropped rapidly to 8-9 volts, while the temperature of the solution stabilized at about 56-58°C. Regular sampling and analysis of total organic carbon (TOC). The results, shown in Figure 10, show that the decrease in TOC appears to be due to the possible complete oxidation of the phenol to carbon dioxide, which is then removed from the solution as a gas. Example II

In order to show the decolorization effect in textile industry effluent water, a 1 liter solution was prepared with tap water, which contained 0.1 g of textile dye Remazol ^™ Black B (Hoechst Celanese company), 0.1 g of surfactant Tergitol ^™ 15-S-5 (Union Carbide company) and 1 gram of sodium chloride.

The composition of the test solution was similar to typical effluents from textile dyeing and finishing processes, where even very low concentrations of Remazol Black imparted a very dark color to the solution. Remazol Black is a particularly difficult textile dye to process. So far, other methods used to treat Remazol Black, such as by the action of ozone or the use of hypochlorite bleach, have failed to produce the desired depigmentation effect.

In the monopolar electrolyzer installed among the embodiment 1, with 25 ampere constant currents, electrolyze the above-mentioned solution containing Remazol Black. The cell voltage was about 25 volts, and the temperature of the solution reached 52°C. The initial color of the solution was dark blue. After 10 minutes of electrolysis, the color of the solution turned pink, and after 30 minutes, the solution was virtually colorless.

Example III

Further tests were carried out to show the decontamination effect of groundwater. Humic acids are typical pollutants in groundwater produced by the decomposition of plant matter. Water containing humic acid, even in low concentrations, is dark in color, and the color is difficult to remove.

A dark brown solution in tap water was prepared containing 30 ppm of the sodium salt of humic acid (Aldrich) without additives to increase the conductivity of the solution. The solution was circulated through a monopolar electrochemical cell similar to that used in Example 1, but equipped with only one anode and two cathodes. A constant current of 10 amps was applied for 2.5 hours. The cell voltage was 24-25 volts, and the temperature reached 58°C. At the end of the test, the solution was completely clear, indicating effective destruction of humic acids.

Example IV

Further experiments were performed to show the effectiveness of the electrolyzer and method of the present invention in sanitizing and reducing the chemical oxygen demand (COD) of effluent water from food processing plants.

250 ml of wastewater from a Mexican malting plant was treated in an electrochemical cell in a monopolar, open-ended configuration similar to that used in Example 1, except that the total anode area was 6 cm2. Its purpose is to reduce COD, partially or completely decolorize, eliminate microorganisms and odor.

A constant current of 1 amp was applied for 150 minutes; the cell voltage dropped from the initial 22 volts to 17.5 V, and the temperature of the solution reached 44°C.

The results are shown in the table below: surface COD 1700ppm 27ppm color Orange clarify microorganism active Killed the smell have none Example V

Further experiments were performed to show the decolorization efficacy of the electrolyzer and method of the present invention in a one-pass configuration.

A dark violet solution containing methyl violet dye at a concentration of 15 ppm in tap water was circulated in single-pass mode at a flow rate of 250 ml/min through a unipolar, open electrochemical cell similar to that used in Example 1. Its purpose is to achieve complete depigmentation.

A current of 25 amps was applied; the cell voltage was 25 volts, and the temperature of the solution reached 65°C.

After one pass through the cell, a clear solution was obtained.

Example VI

An experiment was carried out to demonstrate the use of an open-structure electrochemical cell for the electrosynthesis of chemicals, in this case sodium hypochlorite.

The electrochemical cell of Example I is replaced with an anode that releases catalytic chlorine, such as the DSA® anode produced by Eltech Systems. A brine solution containing 10 grams per liter of sodium chloride was fed to the electrolysis unit zone, where chlorine was produced at the anode and sodium hydroxide at the cathode. Chlorine and caustic soda are reacted in an electrolytic cell to produce a dilute aqueous solution of sodium hypochlorite bleach.

Example VII

Experiments were performed using the monopolar cell configuration shown in Figure 8 to demonstrate an open cell structure using electrodes comprising several conductive porous elements adjacent to each other and in electrical contact with each other. The cell was equipped with a platinum/niobium woven mesh anode with 10 strands per linear inch. The two platinum/niobium savers are in contact and sit on top of a third platinum/niobium screen as the power supply electrode, which is connected to the positive terminal of a DC power supply. The cathode element was a single nickel screen connected to the negative terminal of the DC power supply.

The electrolyte to be treated consisted of 5 grams of sodium chloride, which was added to 1 liter of 60°C aqueous electroless nickel electrowinning discharge water containing 60 grams of nickel salt, 25 grams of sodium hypophosphite and a COD of 20,000 ppm. Electrolysis was carried out at a cell voltage of 55 mA/cm ² , 5.5 v, until the chemical oxygen demand of the effluent dropped to about 10% of the initial value. The bleed water is then treated in an electrochemical cell with a high surface area carbon cathode to electrodeposit most of the nickel remaining in solution.

This shows that the compounding agent in the discharge water of the electroless plating tank is destroyed, and the released metal ions are recovered by electrowinning.

Although the present invention is collectively described with different specific examples, they are for illustrative purposes only. Accordingly, those skilled in the art will recognize many alternatives, improvements and changes from the foregoing detailed description, and all such alternatives and changes are therefore encompassed within the protection scope of the appended claims.

Claims (40)

1. electrolyzer is characterized in that an Open architecture and comprises and be arranged at least one anode and at least one negative electrode of an electrolyzer district as electrode; This electrode position is fully approaching each other, the loss of bath voltage and IR can be reduced to the gap that a minimum electrode is asked to provide; Be used for electrolyte solution is added directly to the member of this electrode in this electrolyzer district, and be used for regulating the member of this electrolyte solution at the residence time in this electrolyzer district.

2. as the electrolyzer of claim l, wherein this Open architecture is characterised in that control electrolyte solution and/or the gaseous by-product seepage from this electrolyzer district.

3. electrolyzer as claimed in claim 1 is characterized in that an electric purifying electrolyzer that is used to handle polluted water solution.

4. electrolyzer as claimed in claim 1 is characterized in that an electrosynthesis electrolyzer that is used to prepare the organic or inorganic chemical.

5. electrolyzer as claimed in claim 1 is characterized in that the described electrode that is connected in an one pole or dipolar configuration.

6. electrolyzer as claimed in claim 5 is characterized in that at least one comprises the electrode of several electroconductibility multihole devices that contact with electric power each other adjacent one another are.

7. electrolyzer as claimed in claim 6, this electroconductibility multihole device that it is characterized in that this electrode is with metal or carbon manufacturing.

8. electrolyzer as claimed in claim 6 is characterized in that this electroconductibility multihole device of this electrode comprises the material that is independently selected from perforated metal, welded wire cloth, woven wire cloth, expanded metal, carbon felt, braiding carbon cloth, reticulated vitreous carbon and metal foaming material.

9. electrolyzer as claimed in claim 6, wherein this electrode comprises several electroconductibility multihole devices, it is characterized in that a transmitting electrode and from 1 to 100 electrical multihole device of additional guide that is connected with this transmitting electrode electric power.

10. electrolyzer as claimed in claim 1 wherein should be characterised in that the combination of pumping element, control valve member or pumping element and control valve member in order to the member of regulating residence time.

11. electrolyzer as claimed in claim 1 is characterized in that being used for electrolyte solution is distributed in the whole member of this electrode equably.

12. electrolyzer as claimed in claim 1, but wherein this anodic is characterised in that electrocatalysis produces the reactive oxygen product.

13. as the electrolyzer of claim 12, wherein this electrocatalysis anodic is characterised in that its manufactured materials is selected from rare metal, stannic oxide, plumbic oxide, substoichiometric titanium oxide and adulterated diamond.

14. electrolyzer as claimed in claim 1, but wherein this negative electrode is characterised in that the destruction of electrocatalysis nitrate.

15. electrolyzer as claimed in claim 1, wherein this negative electrode is characterised in that to being suitable for hydrogen reduction is become the gas diffusion cathode of water or superoxide.

16. electrolyzer as claimed in claim 1 is characterized in that an electrochemical cell of not separating.

17. electrolyzer as claimed in claim 1 is characterized in that existing an electrolyzer separation scraper, to form anolyte chamber and catholyte liquid chamber between this anode and negative electrode.

18. electrolyzer as claimed in claim 1 is characterized in that at least one transmitter is selected from pH value, UV-light, visible light conduction property, hydrogen and chlorine.

19. electrolyzer as claimed in claim 1 is characterized in that at least one power supply is selected from direct supply, AC power, the pulse power and battery supply.

20. electrolyzer as claimed in claim 1, it is characterized in that sensor component and computerized member, this computerization member in order to receive from the input data of sensor component with output signal is provided, controlling at least a operational condition in this electrolyzer, it is selected from current density, electrolyte solution flow velocity, temperature and the electrolytical pH-value to this electrolyzer.

21. a method that is used for the contaminated aqueous solution of electric purifying is characterized in that the following step, it comprises:

(ⅰ) provide an electrolyzer, it comprises an Open architecture, is arranged at least one anode and at least one negative electrode of an electrolyzer district as electrode; This electrode position is fully approaching each other, the loss of bath voltage and IR can be reduced to minimum interelectrode gap to provide; Be used for a contaminated electrolyte solution is added directly to the electrode member in this electrolyzer district, and be used for regulating this electrolyte solution at the member of this electrolyzer district residence time with modification pollutent wherein;

(ⅱ) in the electrolyzer of (ⅰ), add a contaminated electrolyte solution; And

(ⅲ) electrode at this electrolytic cell applies a voltage, with this contaminated aqueous solution of electrolysis and modification pollutent wherein.

22. as the electric purification process of claim 21, wherein the Open architecture of this electrolyzer is characterised in that the seepage of control electrolyte solution and/or gaseous by-product.

23., it is characterized in that the electrode of this electrolyzer is connected in an one pole or dipolar configuration as the electric purification process of claim 21.

24., it is characterized in that in this electrolyzer at least one comprises several adjacent one another are and electrodes of the electroconductibility multihole device of electric power contact each other as the electric purification process of claim 23.

25. as the electric purification process of claim 21, it is characterized in that the electrolyte solution with water that is added directly to this electrode comprises pollutent, it is selected from organic compound, mineral compound, microorganism, virus, metal ion and composition thereof.

26. as the electric purification process of claim 21, it is characterized in that electrolyte solution with water comprises microorganism, it is selected from bacterium, spore, cyst bacterium, protozoon, fungi and composition thereof.

27. as the electric purification process of claim 21, the electrolyte solution with water that it is characterized in that being added in this electrolyzer comprises a dyestuff or other colorific pollutents, the electrolyte solution with water that reaches the modification of reclaiming from this electrolyzer is colourless basically.

28. as the electric purification process of claim 21, it is characterized in that in electrolyte solution with water adding under the condition of current-carrying medium of quantity of the destruction that is enough to promote pollutent, carry out electrolytic action.

29. as the electric purification process of claim 28, wherein this current-carrying medium is a kind of alkaline matter or a kind of acidic substance that are selected from acid, acid salt and acidic cpd.

30., it is characterized in that in electrolyte solution with water, adding the step of the salt of capacity, in purified solution so that a reactive halogen resistates to be provided as the electric purification process of claim 21.

31., it is characterized in that the electrolyte solution with water that is added into this electrolyzer is subjected to metal ion pollution as the electric purification process of claim 21.

32. as the electric purification process of claim 31, it is characterized in that the toxic metal of this metal ion from plating tank discharge water, metal dissolution fluid, kill livestock thing preparation and coating, this metal can be by a recombiner, tensio-active agent or reductive agent chelating.

33. as the electric purification process of claim 32, it is characterized in that this recombiner of modification, tensio-active agent or reductive agent in this electrolyzer, to discharge metal ion in this electrolyzer, further to handle or to transfer to a metal recovery electrolyzer.

34. a method that is used for the electrosynthesis chemical is characterized in that the following step, it comprises:

(ⅰ) provide an electrolyzer, it comprises an Open architecture, be arranged at least one anode and at least one negative electrode of an electrolyzer district as electrode, be used for electrolyte solution is added directly to the member of this electrode in this electrolyzer district, and be used for regulating the member of this electrolyte solution at the residence time in this electrolyzer district;

(ⅱ) add ionogen in the electrolyzer of (ⅰ), it comprises a kind of solution of electroactive matrix; And

(ⅲ), form a useful products with this ionogen of electrolysis in the electrode application voltage of this electrolytic cell.

35., it is characterized in that the electrode of this electrolyzer is connected in an one pole or dipolar configuration as the electrosynthesis method of claim 34.

36., it is characterized in that at least one comprises several electrodes adjacent one another are and the electroconductibility multihole device that is electrical contact with each other as the method in order to the electrosynthesis chemical of claim 35.

37. as the method in order to the electrosynthesis chemical of claim 36, the electroconductibility multihole device that it is characterized in that this electrode is with metal or carbon manufacturing.

38., it is characterized in that this ionogen comprises a kind of salt or a kind of aqueous acid as the method in order to the electrosynthesis chemical of claim 34.

39., it is characterized in that this useful products is an inorganic or organic compound as the method in order to the electrosynthesis chemical of claim 34.

40., it is characterized in that the electrolyzer of (ⅰ) comprises a porousness barrier film or a selectively permeable membrane as the method in order to the electrosynthesis chemical of claim 34.

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