JPH0341784Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a compact electrodialysis device for desalinating small amounts of salt water. More specifically, it is a small-sized product designed for desalting extremely small volumes of salt water, such as when removing salt from samples such as liquid chromatography preparative solutions to improve the accuracy of qualitative and quantitative analysis of contained organic matter. The present invention provides a desalination device.

BACKGROUND TECHNOLOGY An electrodialysis system that is generally used industrially consists of an electrodialysis tank that first incorporates an ion exchange membrane and a chamber frame between an anode and a cathode and tightens them from both ends; It is composed of a tank and pump group for supplying liquid to the third electrodialysis tank, a power supply unit that supplies direct current to be applied to the third electrodialysis tank, and a fourth control unit that performs various controls.

Since these industrial-scale electrodialysis systems have a relatively large volume of liquid to be treated, the electrodialysis tank has a large number of membranes and chamber frames stacked alternately to increase the membrane area per device. Furthermore, since the liquid to be treated is specified, there is no need to frequently dismantle the electrodialysis tank to replace the membrane or clean the inside of the piping.

However, when attempting to desalt an unspecified large number and small amount of samples such as liquid chromatography preparative solutions, the structure of the dialysis tank requires an anion exchange membrane or a neutral membrane between the electrode frames. A three-chamber structure with a salt chamber frame, a cation exchange membrane, or a neutral membrane is preferable, and the membrane can be easily replaced with a new one for each sample, and the piping can be cleaned so that no previous sample remains. You have to do it the same way. Furthermore, it is important that the overall operation is simple and that the entire device is desirably small.

Problems that the invention aims to solve Conventionally, a three-chamber desalination cell has a pair of ion exchange membranes or neutral membranes placed between the electrode frames, and a desalination chamber formed between the membranes. A method of filling and dialyzing a sample is known. In this case, the capacity of the sample that can be desalted is limited by the capacity of the desalting chamber, and the desalting chamber must be stirred with a rotor, etc., so the size of the desalting chamber cannot be made sufficiently small. Undesirable because of its drawbacks.

Regarding the automation of equipment, for example,
-35472 and Japanese Patent Application Laid-Open No. 110982/1982, both of them are effective in industrial-scale equipment, but they are extremely difficult to implement when desalting a very small amount of sample. be.

The purpose of the present invention is to solve the above-mentioned problems, and to provide a compact electrodesalination device that allows easy replacement of membranes and chamber frames, allows desalination of small amounts of samples with simple operations, and moreover, is compact. .

Means for Solving the Problems The electrodesalination device of the present invention has a membrane area of 0.5 cm ² or more and 100 cm ² or less so that a small amount of sample can be desalinated, and the sample is circulated by a pump outside the dialysis tank. In addition, the electrodialysis tank, liquid container and pump, DC power supply, and control device are all fixed or housed in one case, and the desalination cell and piping are controlled electrically. By automatically performing a series of operations such as washing with water, circulating the sample solution and electrode electrolyte, applying direct current, determining the end of desalination, stopping the direct current, and collecting the sample solution into a container, it is compact and Moreover, the sample can be desalted with simple operations.

Example An example of the desalination apparatus of the present invention is shown in FIG. An electrodialysis cell is constructed by placing and tightening an integrated unit that incorporates a membrane and a chamber frame between an anode frame and a cathode frame. Either the anode frame or the cathode frame is fixed to the case of the device, and is configured to be fastened to the other movable electrode frame using fasteners such as bolts and nuts. In Figure 1, a tube type pump with a two-channel system and capable of forward and reverse rotation is used as the pump. Channel 3 circulates the electrode electrolyte respectively. The sample container and the electrode electrolyte container are each equipped with a liquid forward nozzle and a return path nozzle, but the forward path nozzle is installed as low as possible in the container, and the return path nozzle is installed above the liquid level to improve efficiency. When liquid circulation is established and the pump is rotated in reverse,
Almost all of the liquid can now be collected into a container.

The current value display section is a section that displays the current value when desalination operation is performed by applying a constant voltage DC current to the dialysis tank, and allows you to grasp the desalination status. It is possible to automatically determine that desalination is complete and stop the desalination operation. This takes advantage of the fact that when desalting is carried out by the constant voltage method, the electrical conductivity decreases as the salt concentration of the sample decreases, so the applied current decreases according to Ohm's law. Furthermore, when a constant current is used as the DC power source, the voltage of the dialysis tank increases as desalination progresses, so it can be controlled in a similar manner. It is preferable that the current value or voltage value can be arbitrarily set in order to correspond to the properties of the sample and the desired degree of desalination.

A single automatic operation start switch is sufficient, but to expand functionality, a switch for only flushing or a switch for only desalination may be provided.

A schematic flow diagram of the device is shown in Figure 2. By pressing the automatic operation start switch, the desalination chamber and piping of the dialysis tank are first washed in the water washing line 5,
Next, the sample circulation line 1 is switched and energization is started. When the desalination is completed, the current supply is stopped, and the pumps 2 and 4 rotate in reverse to collect the sample and the electrode electrolyte into the container, and then the pumps 2 and 4 are stopped. Collecting the sample into a container when desalting is completed is extremely important when desalting a small amount of sample. In other words, if the sample after desalination is in contact with the electrode chamber solution for a long time through the membrane, salt from the electrode chamber solution may diffuse into the sample that has been desalted, or conversely, valuable components in the sample may be transferred to the electrode. This is because it diffuses to the room liquid side.

It is also possible to notify by a buzzer or the like when the above series of steps are completed. All of the above controls are performed using timers, relays, and solenoid valves.

The current carrying area of the membrane used in this desalination equipment is 0.5
It is not less than cm ² and not more than 100 cm ² , preferably not more than 5 cm ² . It is also preferable that the thickness of the demineralization chamber in the unit be as small as possible, with a thickness of 0.2 cm ² or more and 1 mm or less being used.
Reducing the membrane area and the thickness of the desalting chamber is preferable because it reduces the volume of the desalting chamber and allows a smaller amount of sample to be desalted. It is also desirable to keep the inner diameter and length of the piping as small as possible for the same reason.
Use a Teflon tube or the like with an inner diameter of about 0.5 mm to 2 mm. By taking these into consideration, it becomes possible to desalt a sample as small as 1 ml.

This invention specifically relates to a three-chamber type desalting apparatus, but if it is necessary to maintain the pH of the sample, a buffer chamber can be provided across the desalting chamber to create a five-chamber type desalting apparatus. It is also possible, in which case the buffer chamber is filled with or circulated with an aqueous solution of a specific salt or a buffer.

Effects of the invention The electrical desalination apparatus of the invention is extremely compact as a whole, and can desalt a small amount of sample of about 1 ml with simple operation and according to the purpose.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the tabletop electric desalination apparatus of the present invention, and FIG. 2 is a schematic diagram of a liquid flow. 1... Sample circulation line, 2, 4... Pump, 3... Electrolyte circulation line, 5... Water washing line.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Current-carrying area of a membrane consisting of an anion exchange membrane or a neutral membrane, a demineralization chamber frame, a cation exchange membrane, or a neutral membrane arranged in sequence between an anode frame and a cathode frame. is 0.5cm2 ^or more
In an electrodesalination apparatus having a three-chamber electrodialysis tank of 100 cm ² or less, a circuit 1 is provided to circulate the sample solution supplied to and drained from the demineralization chamber via a pump 2, and a The electric pump is characterized in that desalination is carried out while stirring the interior of the desalination chamber, and that the pump can be rotated in forward and reverse directions, and that dialysis can be performed by forward rotation and the desalted solution can be recovered by reverse rotation. Desalination equipment. 2. The electric desalination apparatus according to claim 1, which has a circuit 3 for circulating an electrode electrolyte via a pump 4. 3. The electric desalination apparatus according to claim 2, wherein the pump 4 can be rotated in forward and reverse directions to recover the electrode chamber liquid. 4 The electrodialysis tank is one to which a constant-voltage direct current is applied, and is equipped with a means to automatically judge the end of desalination based on a drop in the current, stopping the direct current and removing the desalting solution and electrode The electrodesalination apparatus according to claim 3 of the utility model registration, wherein the chamber liquid is automatically collected into a container. 5 The electrodialysis tank is one to which a constant direct current is applied, and is equipped with a means for automatically determining the end of desalination by a rise in voltage, and is equipped with a means to automatically judge the end of desalination by a rise in voltage, and to stop the direct voltage and remove the desalination solution and electrodes. The electrodesalination apparatus according to claim 3 of the utility model registration, wherein the chamber liquid is automatically collected into a container. 6. The electrodesalination apparatus according to any one of claims 1 to 5, wherein a pipe 5 for passing a cleaning liquid is connected to a circuit for circulating a sample liquid. 7 Practical equipment that has a means to automatically perform a series of steps such as cleaning the piping and demineralization chamber, circulating the sample solution and electrode chamber solution, applying direct current, completing desalination, and recovering the desalination solution and electrode chamber solution. The electrical desalination apparatus according to claim 6 of the patent registration claim. 8. Scope of Utility Model Registration Claim Paragraph 1, in which the sample chamber and electrode chamber liquid pumps and containers, electrodialysis tank, DC power supply, control device, etc. are all housed or fixed in one case and integrated. The electrodesalination apparatus according to any one of Items 7 to 8.