KR20040065373A - Electrosorption Equipments for Selective Removal of Inorganic Ions in Liquid Waste - Google Patents

Abstract

PURPOSE: An electrosorption equipment for selectively removing inorganic ions in waste solution is provided to increase electrosorption speed, electrosorption capacity and waste solution treatment capacity, adjust height of working electrode, easily assemble the equipment and fabricate the equipment more economically. CONSTITUTION: The electrosorption equipment is characterized in that a working electrode is formed of a cylinder type rigid activated carbon fiber powder compact so that current or voltage is uniformly distributed in the working electrode, wherein cells composing a multi-cell are formed in a double pipe shape on concentrical axis, an inner part of counter electrode(2) is installed at an outer part of the working electrode(1) requiring wide surface area, and a membrane tube(3) is installed between the working electrode and the counter electrode to prevent oxidation and reduction at the counter electrode and convection to the counter electrode, wherein current collector plates are installed at a concentric outer part of working electrode bed, and wherein the electrosorption equipment comprises a counter electrode supporting lower plate(8) which supports the counter plate, and in which a counter electrode chamber(6) is formed; a working electrode supporting lower plate(9) directly put on the counter electrode supporting lower plate and positioned under the working electrode; working electrode chamber channel lower plates(10) directly put on the working electrode supporting lower plate and contacted with the working electrode supporting lower plate; current collector plates(11,12,13) installed between the working electrode chamber channel lower plates; a working electrode chamber channel upper plate(14) which is positioned on an upper part of the current collector plates, and in which a working electrode chamber is formed; a working electrode supporting upper plate(15) positioned on an upper part of the working electrode chamber channel upper plate; a membrane tube supporting upper plate(16) which is positioned on an upper part of the working electrode supporting upper plate, and in which a counter electrode chamber(7) is formed; a counter electrode supporting upper plate(17) positioned at an uppermost part of the membrane tube supporting upper plate; bolts and current collector rods(18) for penetratingly clamping the plates; and O-rings(19) installed between the respective plates.

Description

Electrosorption Equipments for Selective Removal of Inorganic Ions in Liquid Waste}

The present invention relates to an electroadsorption device for selective removal of inorganic ions from waste liquid.

Although solid waste recycling technology, especially metal waste recycling technology, which has a large effect on resource recycling and disposal reduction of nuclear cycle facilities, has proved to be effective as electrolytic decontamination technology or chemical decontamination technology, total decontamination cost is required to improve the efficiency of decontamination technology. Complete disposal of secondary waste, which accounts for more than 40% of the total, is essential.

Such wet decontamination waste liquid is present alone or mixed with the radioactive radionuclides removed, such as Co, Cs, and Sr, and has a high acidity or basicity due to the chemicals used to control the dissolution process during the decontamination step. Electrolyte salt waste solution contains various electrolytes such as neutral salt (Na ₂ SO ₄ , NaNO ₃ , Na ₂ C ₂ O ₄ ) or acidic (H ₃ PO ₄ , HNO ₃ ). need.

Ion exchange, sedimentation, and evaporation and concentration methods are used as the existing technologies for the treatment of secondary wastes. However, due to the limited economic efficiency and treatment efficiency, the secondary waste volume is less efficient and the operation conditions and process control are simpler. In addition, intensive R & D investments are being made in the development of electrochemical methods with the advantages of lower equipment investment and operating costs.

In addition, the uranium-containing sludge wastes generated during the operation of the fuel conversion facility, which manufactures uranium dioxide powder for nuclear fuel from natural uranium concentrates, contain tens of thousands of ppm of various chemical salts (NH ₄ NO ₃ , NaNO ₃ , Ca (NO ₃ ) ₂ , CaCO). ₃ ) and hundreds of ppm of uranium and dozens of ppm of heavy metals are difficult-to-treat radioactive chemical salt liquid wastes, which are microbial reduction / precipitation, ion exchange, and activity methods for removing or recovering uranium (VI) from general waste liquids. Methods such as adsorption by alumina or activated carbon have limitations in application due to limited removal capacity when the uranium (VI) concentration in the waste liquid is high.

Therefore, the electrodeposition method that can be effectively used for the treatment of metal ions by various porous carbon electrode materials can be considered as the treatment technology for the wastewater containing low concentrations of uranium in the decontamination waste liquid or high concentration chemical salts having such characteristics. It cannot be used in a practical way to remove uranium, strontium, or the like, which has a very high reduction potential of the metal.

As an alternative to the electrodeposition technique, an electrosorption method may be used.

Electrosorption technology is a technique in which an electric driving force is added to an existing adsorption / ion exchange mechanism, and has a reversible characteristic that facilitates the purification of waste liquid by adsorption removal of contaminants and concentration of contaminants by desorption. Adsorbents used at the same time as desorption can be regenerated, so there is no secondary waste generation, and there is less pollution, efficient use of energy, and lower cost compared to ion exchange, reverse osmosis, electrodialysis and evaporation. Technology.

Electrode, which is one of the main components of electrosorption, should be stable in the range of available voltage to prevent deterioration of adsorbed electrode or generation of by-products, and should have continuous electrical contact and excellent electrical conductivity as well as electrochemical activity. It must have a high specific surface area of porosity so that the fluid can easily penetrate the paper electrode contact with the pores.

In addition, in order to effectively use in commercialization facilities, the adsorbent electrode should be easily handled, manipulated, and processed. It is known that carbon electrode is excellent as an electrode material having such material characteristics.

The carbon body has high electrical conductivity, excellent chemical and heat resistance, and particularly high durability against radioactivity, and thus has an effective characteristic for treating radioactive waste liquid.

Activated carbon, which is the most easily available in the carbon body, has been widely used for the treatment of waste liquid and polluted gas phase for a long time, but it is inconvenient to handle as granular or powder, and has a relatively low specific surface area. Activated Carbon Fiber (ACF) has a specific surface area that is significantly larger than that of conventional granular activated carbon, and has a high adsorption rate and excellent reproducibility due to its uniform pore structure consisting of only micropores. The furnace adsorbent was found to be very good.

Therefore, various electroadsorption cells have been proposed as an electrosorption apparatus to which an electrosorption technique using the ACF as an electrode can be applied.

According to the number of working electrodes, it can be divided into single cell with one working electrode and multi-cell with two or more working electrodes.

In the case of a single cell mainly using three electrodes (working electrode, counter electrode and reference electrode), it is easy to control the process by precisely adjusting the potential or current, but it is economical and the processing flow rate is limited. For this purpose, a multi-cell using two electrodes (working electrode and counter electrode) is mainly required.

These multi-cells can be connected in parallel to increase throughput, in which case each ACF electrode acting as a working electrode can be used in both axial and radial directions without the need for excessive local current or voltage. Therefore, it is necessary to distribute the current or voltage uniformly, and in order to increase the adsorption capacity of each ACF electrode, the solution resistance between the working electrode bed and the counter electrode located on the concentric inner axis The current charging time should be the same along the bed axis because it is constant along the axis. In addition, there is a need for a device capable of easily adjusting the height of the working electrode, assembling a constituent device, and manufacturing more economically, but such a device has not been developed yet.

An object of the present invention for solving the above problems is to distribute the current or voltage uniformly in both the bed axial and radial directions of each ACF electrode of the multi-cell connected in parallel The solution resistance between the working electrode bed and the counter electrode positioned on the concentric inner axis is constant along the bed axis to increase the electrosorption rate, the electrosorption capacity, and the waste treatment capacity, and the height of the working electrode. An object of the present invention is to provide an electroadsorption device for selective removal of inorganic ions from waste liquid which can be adjusted, the assembly of the device being easy, and more economical.

1 is a view showing a state in which a cell is charged in the electrosorption apparatus for the selective removal of inorganic ions in the waste liquid according to the present invention,

2 is a view of a state in which the cell is excluded in the electrosorption apparatus for the selective removal of inorganic ions in the waste liquid according to the present invention,

3 is a top view of the electrosorption device based on three multi-cells,

4 is a three-dimensional and front view of the counter electrode room and the working electrode room in the electrosorption apparatus based on three multi-cells;

5 is a view showing a counter electrode supporting lower plate in an electroadsorption apparatus based on three multi-cells;

6 is a drawing of the working electrode first plate in the electrosorption apparatus based on three multi-cells;

7 is a drawing of the working electrode second plate in the electrosorption apparatus based on three multi-cells;

8 is a view of the third working electrode plate of the electrosorption apparatus based on three multi-cells;

9 is a view of the membrane tube support top plate in the electrosorption apparatus based on three multi-cells;

FIG. 10 is a view illustrating a counter electrode supporting upper plate in an electroadsorption apparatus based on three multi-cells.

<Description of the symbols for the main parts of the drawings>

(1): working electrode (ACF molded body)

(2): counter electrode (graphite rod, carbon rod, stainless rod, platinum coated copper rod)

(3): Membrane tube (Vycor tube)

(4): Inlet of treatment waste liquid (inflow of working electrode room)

(5): Outlet of treatment waste liquid (outflow of working electrode room)

(6): electrolyte solution inlet (relative to electrode room)

(7): electrolyte solution outlet (relative to electrode room)

(8): counter electrode supporting lower plate

(9): working electrode supporting lower plate

(10): working electrode chamber flow path lower plate

(11): first current collector plate

(12) a second current collector plate

(13): third current collector plate

(14): working electrode chamber upper plate

15: working electrode support upper plate

(16): membrane tube support top plate

(17) counter electrode support upper plate

(18): Bolt & current collector rod

(19): O-ring

The present invention, which achieves the object as described above and performs the task for eliminating the conventional defects, uses a rigid ACF molded body as a working electrode, and replaces a current collector coil or a wire that has been used in the past. It is characterized by using a current collector plate (current collector plate) and laminated and installed a multi-stage current collector plate (current collector plate) in the axial direction of the bed (bed).

Hereinafter, the configuration and the operation of the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view of a state in which a cell (cell, working electrode and counter electrode) is loaded in the electrosorption apparatus for the selective removal of inorganic ions in the waste liquid according to the present invention, Figure 2 is a view of the inorganic ions in the waste liquid according to the present invention Figure 3 is a view of a state in which a cell is excluded in the electrosorption device for selective removal, FIG. 3 is a top view of the electrosorption device based on three multi-cells, and FIG. 4 is a multi-cell of three devices. A three-dimensional and front view of the counter electrode room and the working electrode room is shown in the electrosorption apparatus based on

Referring to the configuration of the present invention with reference to Figure 1 may be composed of a plurality of cells (cell) that operates in a flow-through type, for example, based on three cells (cell), the cell (charge) is charged It shows the state.

Each cylindrical cell has a double tube shape, in which two electrodes (working electrode and counter electrode) are located on the concentric axis.

The working electrode 1, which requires a large surface area, is provided on the outside and the counter electrode 2 on the inside,

In order to prevent oxidation and reduction at the counter electrode and to prevent convection to the counter electrode, a membrane tube 3 is provided between the two electrodes on the concentric axis.

A rigid ACF molded body is used as the working electrode, and carbon materials, graphite rods and stainless steel rods, and platinum coated copper rods may be used as the material of the counter electrode.

In addition, the membrane tube (membrane tube) may be installed a bi-core tube (Vycor tube, outer diameter 10mm, thickness 1.1mm).

In each working electrode room and the counter electrode room, the waste and electrolytic solutions to be treated are circulated or passed through, respectively.

Each cell is connected to an electrostatic potential (or constant current) supply and regulated power supply that supplies a wide range of potentials (or currents) in parallel.

For comparison, FIG. 2 shows a state of the electrosorption apparatus in which the cell is removed.

FIG. 5 is a view illustrating a counter electrode supporting lower plate in the electrosorption apparatus based on three multi-cells, and the counter electrode supporting lower plate 8 has a lower end supporting the counter electrode 2. It is made of material MC 910 as a plate of.

The counter electrode is installed in a Vycor tube and manufactured to have a structure in which an electrolyte solution can be injected into the counter electrode room from the outside.

FIG. 6 shows a drawing of a working electrode first plate in an electroadsorption apparatus based on three multi-cells. The working electrode supporting lower plate 9 is an ACF molded working electrode and a Vycor tube. A plate that prevents the solution from being mixed between the plates is placed directly above the counter electrode support lower plate 8 and sealed using an O-ring 19 between the two plates.

The working electrode support plates 9 are positioned one above and below the working electrode 1 to fix the working electrode 1 and are processed into a conductor such as SUS 304 so that a current flows.

FIG. 7 shows a drawing of the working electrode second plate in the electrosorption apparatus based on three multi-cells. The working electrode flow path lower plate 10 is directly above the working electrode support lower plate 9. It is placed in the plate through which the electrolyte solution passes through the working electrode side of the ACF molded body, and the waste liquid must be introduced and entered in three directions at the same time. The plate is processed with a conductor such as SUS 304.

FIG. 8 shows a drawing of the working electrode third plate in the electrosorption apparatus based on three multi-cells. The current collector plates 11, 12 and 13 are in contact with each ACF. It is used to maintain the uniformity of the current, and also enters between the working electrode flow path plates to control the height of the ACF molded bed.

The plates are processed with a conductor such as SUS 304.

The working electrode flow path upper plate 14 is made of the same function and material as the working electrode flow path lower plate 10 of FIG. 7.

The working electrode support upper plate 15 is made of the same function and material as the working electrode support plate 9 of FIG.

FIG. 9 shows a diagram of a membrane tube support upper plate in an electroadsorption apparatus based on three multi-cells, wherein the membrane tube support upper plate 16 is discharged from an electrolyte solution used for three counter electrodes. In part, the electrolyte used is collected and discharged.

Also, it is made of MC 910 material to fix the membrane tube composed of bi-core tube material and to fix the counter electrode.

FIG. 10 shows a counter electrode support top plate diagram of an electroadsorption apparatus based on three multi-cells. The counter electrode support top plate 17 is located at the top of a portion supporting three counter electrodes. It is made of MC 910 so that electrolyte solution does not overflow or spill from the bottom.

Bolt and current collector rods made of SUS 304 for connection to the electrostatic potential (or constant current) supplying and regulating power supply for supplying a wide range of potentials (or currents) together with the fastening of the plates. 18 is installed.

In addition, the O-rings 19 of the Viton-based rubber materials 31013, 31017, and 32035 are installed to prevent leakage or mixing of the waste solution or the electrolyte solution of the electrode between the plates.

Hereinafter is a preferred embodiment of the present invention.

Example 1

Continuously stir the decontamination waste solution containing various radionuclides (or metal ions) or the uranium-containing waste solution in the high concentration chemical salt using a stirrer, and then through the working electrode chamber inlet (4) using a peristaltic pump or a quantitative pump. It is to be introduced into the working electrode (1), which is an ACF molded body in which nuclides or uranium are removed from the waste liquid to be removed by electrosorption. The waste liquid to be treated flows upward after being introduced and is discharged through the working electrode outlet outlet 5 at the top.

At this time, the electrolyte solution is installed on the concentric axis of the ACF molded object electrode 1 and is isolated from the contact of the solution by the vycor tube. After flowing in and flowing upward, it is discharged through the counter electrode outlet 7 at the top.

When it is confirmed that the solution is circulated at a constant flow rate without any leakage in each electrode room, a constant potential or current is applied to the electrosorption apparatus through a potentiostat / Galvanostat or a DC power supply. .

Afterwards, the change of potential or current and the concentration of radionuclides or uranium ions in the waste liquid are measured according to the time to determine the exchange time of the working electrode of the ACF molded body. When detected, a peristaltic pump or metering is used to stop the supply of a constant potential or current that was available to the potentiostat / galvanostat or DC power supply and to stop the circulation of the solution circulated to each electrode chamber. Stop the pump. The saturated ACF shaped working electrode is then reused or discarded after regeneration by electrodesorption. Therefore, the above-mentioned electroadsorption process is repeated by charging the regenerated ACF molded working electrode or a new ACF molded working electrode.

In addition, the electrosorption process is performed in the same way for each of the multi-cell (multi-cell) connected in parallel.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

The present invention as described above has the advantage that the current or voltage is uniformly distributed in both the bed axial direction and the radial direction of each ACF electrode of the multi-cell connected in parallel,

The solution resistance between the working electrode bed and the counter electrode located on the concentric inner shaft is made constant along the bed axis to increase the electrosorption rate, electrosorption capacity, and waste disposal capacity.

It is a useful invention that the height of the working electrode and the assembly of the component can be easily and more economically manufactured, and thus the use thereof is greatly expected in the industry.

Claims (5)

Electro-adsorption device connected in parallel flow by operating in flow-through type for the purpose of electro-adsorption of waste liquid containing uranium in decontamination waste liquid or high concentration chemical salt In The working electrode is a cylindrical rigid ACF molded product so that the current or voltage is distributed uniformly in the working electrode, Each cell constituting the multi-cell is located in the form of a double tube on the concentric axis, and the working electrode 1 which requires a large surface area is provided on the outer side, and the counter electrode 2 is formed on the inner side. Electrode adsorption device for selective removal of inorganic ions from waste, characterized in that a membrane tube (3) is installed between the two electrodes to prevent oxidation and reduction and to prevent convection to the counter electrode. The method of claim 1, Current collector plate (current collector) on the concentric outer side of the working electrode bed to increase the rate of adsorption and the capacity of adsorption so that the current or voltage is uniformly distributed in the radial direction of the bed to each ACF molded electrode. Electrochemical adsorption device for selective removal of inorganic ions in the waste liquid, characterized in that the installation, including a plate). The method of claim 2, The current collector plate has a uniform current or voltage in the axial direction of each ACF molded electrode bed, and a solution resistance between the working electrode bed and the counter electrode located on the concentric inner axis. Along the bed axis, the adsorption speed and the adsorption capacity can be increased, the height of the bed can be easily adjusted and the current collector plate can be easily installed, and the bed can be manufactured more economically. Electrode adsorption device for selective removal of inorganic ions in the waste liquid, characterized in that the stack is installed in a multi-stage current collector plate in the axial direction (bed) and fixed at both ends. The method of claim 2, The multi-stage current collector plate (current collector plate) and the configuration for fixing the both ends; A counter electrode supporting lower plate 8 which supports the counter electrode 2 from the bottom and has a counter electrode chamber 6 as an electrolyte solution inlet; It is placed directly on the counter-electrode support lower plate 8 and is sealed using an O-ring 19 between the two to prevent the solution from mixing between the ACF shaped working electrode and the membrane tube. A working electrode support lower plate 9 which is placed under 1) and is fixed to it and processed to flow current at the same time; The working electrode chamber 4, which is placed on the working electrode support lower plate 9 and is placed at the inlet of the processing waste solution, is formed so that the waste solution enters the plate through which the electrolyte flows through the working electrode side of the ACF molded body. The working electrode chamber flow path lower plate 10 which can adjust the amount of the waste liquid separately and is in contact with the working electrode support lower plate 9; It is used to maintain the uniformity of the current in contact with each ACF molded body and the current collector plate (11, 12, which enters between the working electrode flow path plate 10 to adjust the height of the ACF molded bed (bed), 13) and, A working electrode chamber flow path upper plate 14 positioned above the current collector plate and serving as an outlet of the processing waste liquid, and having the same function as the working electrode chamber flow path lower plate 10; A working electrode support upper plate 15 positioned on the working electrode flow path upper plate 14 to perform the same function as the working electrode support plate 9; The counter electrode chamber 7 is formed on the working electrode support upper plate 15 and discharges the electrolyte solution used for the counter electrode, thereby collecting and discharging the used electrolyte and fixing the membrane tube and the counter electrode. A membrane tube support top plate 16, Located in the uppermost part of the membrane tube support upper plate 16 to support the counter electrode, and is laminated on the counter electrode support upper plate 17 configured to prevent the electrolyte solution from overflowing or outflowing from the bottom, Bolt and current collector rods for fastening through the plates and connecting them to a potential supply (or constant current) supplying and regulating power supply that supplies a wide range of potentials (or currents) ( 18) with, Electro-absorption device for selective removal of inorganic ions in the waste solution, characterized in that the O-ring (19) installed to prevent leakage or mixing of the waste liquid or the electrolyte solution of the electrode between each plate is installed. The method of claim 2, The current collector plate acts as a support for each ACF molded electrode bed and working electrode and as a protector for preventing electric disturbance of these electrodes from the outside, so that no separate support or protector is required. Electrosorption apparatus for selective removal of inorganic ions in the waste liquid.