LT3290B - Device for electrokinetics removing of salt from masonry - Google Patents

Abstract

A device for electrokinetic desalination of brickwork consists of at least one positive, salt-collecting electrode (2) arranged on or in the brickwork in contact with a buffer material (9) which immobilizes the ions, at least one negative electrode (4) to which a continuous voltage is applied and an arrangement of anodes one electrode of which is in contact with a buffer material for use in the device. The positive electrode is completely coated with a layer of the buffer material, except at the connection ends, and a separating layer (10) is applied to the layer of buffer material.

Description

The invention relates to an apparatus for electro-kinetic salt removal from masonry comprising at least one positive, saline-collecting, electrode in contact with or in the presence of damp porous buffer material and at least one negative electrode to which constant voltage is applied, as well as for the anode systems used in such devices.

There is known an electro-kinetic salt removal device from masonry comprising at least one positive electrode in or on the masonry, in contact with a layer of buffer material that immobilizes ions, and at least one negative electrode connected to a constant voltage source. . 2552796, E04B 1/70, 1985).

The principle of electrokinetic charge separation and ion transfer by applying a constant voltage is used in bulky installations such as seawater salt removal. Methods of salt removal from masonry based on the electrokinetic method are known and practiced. The most common salts that damage buildings are sulfates, chlorides and nitrates. The origin of these salts is diverse.

For example,

- salts are present in building materials which are usually made from natural raw materials,

- fertilizers from the soil which pass through capillary absorption,

- salts dispersed specifically in the cap area,

- salts from the atmosphere (the source of salts may be, for example, acid rain).

Salts in masonry walls are usually hygroscopic and therefore, depending on the humidity of the air, absorb water. As the salt crystal volume increases, the iT hydration pressure increases, which destroys porous building materials. In addition, the effect of these salts is caused by corrosion of masonry walls and steel fasteners.

Electrophysical dewatering methods based on electro-space in porous masonry are only effective when the zeta potential between the porous wall and the electrode is sufficiently high. At very high concentrations of salts, the zeta potential is too low and electro-space drying becomes impossible. In this way, it is necessary to remove enough salts from the walls before applying the electrosmosphere.

The principle of salt removal from masonry walls is based on electrokinetic charge separation.

When a constant voltage is applied, the electrolyte charge (ion) moves in an electric field in the direction of the corresponding electrode and concentrates on or near them. The negative ions, the anions, move to the anode, and the positive ions, the cations, move to the cathode. In this way, excess anions in the masonry can be continuously and significantly removed from the anode. Ion; _: The rate of casting depends on their type, size and external conditions such as pressure, · temperature, solvent and concentration and is:

OH- 0.00167 cm ² / relative volume

Cl- 0.00062 cm ² / relative volume

NO ₃ - 0,00058 cm ² / relative volume

SO ₄ - 0.00059 cm ² / relative volume.

In brickwork, ions move at a much slower rate, but this speed is enough to keep the salt out of the brick for too long.

Known electrokinetic methods for salt removal from masonry are in many cases based on the use of metal anodes. The metal anodes are corroded and the resulting corrosion products are removed from the synthetic material by the trough wall.

Another method of desalting concrete structures is known. In this case, the iron reinforcement in the wall is a cathode and the anions are bound to an anode embedded in the wall by ion exchange resins or a suspension of Ca (OH) ₂ , CaCO ₃ and / or calcium oxide.

In both of these cases, back-diffusion of the reaction products into the bricks was unavoidable. This reduces the effective flow of ions. In addition, managing these processes is expensive and complex.

It is an object of the present invention to provide an electrokinetic device which does not have the disadvantages of the said salt removal devices. Device management and installation must be simple and not costly. In addition, the use of pre-prepared electrodes and electrode systems is contemplated.

According to the invention, the device is distinguished by the fact that all the positive electrode, except its ends for voltage connection, is surrounded by a layer of buffer material, and by the fact that a separating layer is adjoined to this layer of buffer material.

The main advantage of this design is the optimum corrosion protection of the electrode as much as possible with buffer material. In addition, the separating layer forms a barrier to the back diffusion of reaction products - to the brick. Back diffusion can be avoided when the separating layer is adhered to the layer of immobilizing buffer at all points of contact with the masonry.

Other more valuable embodiments of the device according to the present invention are described in claims 2-7.

The invention also relates to anodic systems having an electrode in contact with a buffer material and used in such an electro-kinetic salt removal device. This system is distinguished by the fact that the entire electrode, with the exception of the voltage terminals, is surrounded by a layer of buffer material and that a separating layer is adhered to the layer of buffer material.

Additional embodiments 9-16 of the definition of the invention describe other valuable anodic system designs and variants according to the invention.

The drawings illustrate the subject matter of the invention in more detail. Drawings show:

Fig. 2 shows a schematic view of an apparatus for electro-kinetic salt removal from masonry according to the invention, Fig. another embodiment of the device

Figure 3-5: Various variants of the anode systems of the invention used in a salt removal device.

Fig. illustrates a desalination unit where the openings in the masonry 1 have anodes interconnected by a wire. In addition, all the anodes 2, except the terminals for voltage connection, are surrounded by a layer of buffer material that immobilizes ions. This layer, in turn, is surrounded by a layer of separating ducks which is directly adjacent to the walls of the openings. A constant voltage with respect to the cathode or to the earthed rod 4 is created by connecting the current source 3.

Fig. schematically illustrates a desalination apparatus in which flat anodes 5 are arranged on a wall 1. The anodes, respectively filled with buffer material up to the terminals for voltage connection, are again wired to each other and to the source 3. This creates a constant potential with respect to the earthed rod. In this case, the separating layer of the desalination unit is adhered to the layer of buffer material on only one side facing the wall.

Fig. is a view of a tubular anode system 6 most suitable for installation in masonry openings. The core of the anodic system consists of a metal rod, preferably a copper conductor 7, coated with a conductive synthetic material 8. This core is surrounded by a layer of buffer material 9. Reaction products are bound by this layer by physical and chemical processes. The buffer material is predominantly water, Ca (OH) ₂ , CaCO ₃ and / or CaO or mixtures thereof. Additionally, additives for gel-forming agents are desirable. These agents have immobilizing properties and retain moisture. This avoids the risk of draining the anode environment.

The buffer layer is surrounded by a separating layer 10 from a microporous membrane. In the case of a tubular anode system, the membrane is flush with the walls of the masonry openings.

The rod-shaped anode system 11 is shown in Fig. 4. It is convenient to lay this system in grooves in masonry walls. In this case, the metallic electrode 12, coated with synthetic conductive material, is, except for the two ends for voltage connection, encircled by a layer of buffer material 13, which in turn is separated by a separating layer 14. In the case of a mounted system.

Fig. a flat anode system 16 mounted on the wall 15 is shown. A metallic coil-shaped electrode 17 coated with a conductive synthetic material is disposed in a layer 18 of buffer material between the masonry wall and the layer of buffer material 19.

The anodes may be made of metal, graphite, conductive synthetic material, or metal conductors coated with such synthetic materials, or conductors of graphite fibers in the form of rods, bars, or plates. The buffer consists mainly of water, Ca (OH) ₂ , CaCO ₃ and / or CaO and mixtures thereof. Additionally, supplements for gel forming agents are desirable. These agents have immobilizing properties and retain moisture. This avoids the risk of draining the anode environment. Virtually all gel formulations available on the market can be used. However, agar-agar or carboxymethylcellulose is preferred.

The separating layer of the system in direct contact with the masonry plays a role in the back diffusion of reaction products into the masonry. This type of separator is used in batteries. Separators are porous membranes that, when pore size selected, can pass single ions but do not miss larger agglomerates. Ion-selective membranes are also useful.

Required properties of membranes:

- good ionic conductivity,

- high selectivity in terms of specific ion permeability,

- good wettability,

- high mechanical strength,

- low electrical conductivity,

- chemical resistance to electrolyte and reaction products.

These membranes consist of polyfluoroethylene, asbestos, polyvinyl chloride, polyethylene, that synthetic binder, cellulose fiber, regenerated or stretched synthetic film.

pyrophosphate bound and / or cellulose-reinforced with cellophane

The connected DC voltage must be as high as possible (10 to 50 V) in order for the ion transfer to be fast enough.

The effectiveness of the device and the anode system of the present invention is demonstrated by the results obtained during the operation of the test device.

In the test device, rod-shaped anodes of copper wires coated with a conductive synthetic mat were wrapped in a buffer consisting of 4 wt% carboxymethyl cellulose and 96 wt%

CaCO ₃ , in a layer. The buffer material is covered with a separating layer, a synthetic film used in the production of sausages. These electrodes were installed in the holes in the masonry walls. The holes were located in the evaporation zone of the masonry wall at a height of one meter relative to the foundation. The cathode of the test facility was an iron tube embedded in the soil. The unit worked by applying a constant voltage of 36V. Depending on the salt sediment concentration and the humidity of the surrounding environment, the coulombic anion transformation efficiency coefficient at the anode was 40-50%. 40 g of CaCO _{3 were} consumed in 60 days. The reaction products could be removed from the wall. Analysis of the results showed that over 90% of the reaction products were bound to the electrode.

DEFINITION OF INVENTION

Claims (9)

DEFINITION OF INVENTION An apparatus for electro-kinetic salt removal from masonry, consisting of at least one positive electrode mounted on or on a masonry unit in contact with an ion-immobilizing buffer containing calcium oxide, calcium hydroxide and / or calcium carbonate, and one negative electrode coupled to a constant voltage source, characterized in that it has a separating layer adjoining the buffer material layer, and the positive electrode is contained within the buffer material, except for its ends for voltage connection. 2. A device according to claim 1, characterized in that the separating layer covers the layer of buffer material. 3. A device according to claim 1, characterized in that the electrode is in the form of a rod, a rod or a tube. 4. Device according to claim 1.3, characterized in that the electrode is flat or plate-shaped, lattice or coil-shaped. 5. A device according to claim 1,2, characterized in that when the electrode is flat, the separating layer is on the surface of the buffer material on the masonry side. 6. A device according to claim 1, characterized in that the separating layer is a microporous and / or ion-selective membrane of polytetrafluoroethylene, asbestos, polyvinyl chloride, polyethylene, pyrophosphate, bonded with synthetic binder and / or reinforced with cellulose fiberglass, film. 7. The apparatus of claim 1, wherein the positive electrode is a conductor coated with a conductive synthetic material, either copper or carbon or graphite, or a conductive synthetic material10. 8. The device of claim 1, wherein the buffer layer further comprises a gel-forming material. The apparatus of claim 1, wherein the apparatus is different 15, wherein the buffer layer comprises a water-soluble buffer, an emulsified water buffer, or a wetted buffer.