JPS592524B2 - Dehydration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dehydration method by electroosmosis.

In conventional dehydration by electroosmosis, a filter medium is often used, and water is separated through electric current at the same time as normal filtration (% Publication No. 36-9246, Publication No. 37- and No. 46-10600). , and the effect of current is used auxiliary.

In contrast, the present invention deals exclusively with gel-like substances and paste-like substances that are almost impossible to undergo normal filtration, and generally does not perform normal filtration using pressure or the like at the same time.

For this reason, it is necessary that the electrically drawn water does not return back, but in the case of a gel, there is almost no return of the drawn water, and in the case of a paste, the ion exchange membrane prevents this return due to the properties described below. .

When energized, the ion exchange membrane has selective permeability for positive or negative ions, but has the property of allowing water to permeate in the same direction as the ions.

The magnitude of this phenomenon of electrophoresis in membranes varies greatly depending on the structure of the membrane, the concentration of the liquid, etc., but in general, the higher the water content of the membrane is, and the lower the ion concentration in the liquid, the greater the electrophoresis. According to these conditions, the electropermeation in the membrane can be made very large.

Ion-exchange membranes are generally dense and have almost no permeation of water due to pressure, and the movement of water due to diffusion is usually extremely slow.

The ion exchange membrane is also a type of gel that has an electric charge, but because it has a dense crosslinked structure inside, it does not contract even though water passes through it when electricity is applied.

From the properties of ion exchange membranes as described above, it can be concluded that ion exchange membranes are the most suitable diaphragms to use when dehydration is carried out exclusively by electrical action.

Dehydration from the gel can also be achieved by bringing both electrode plates into direct contact with the gel without using a membrane.

However, in this case, the reaction at the electrode causes a chemical change in the object, which is generally not preferred.

Especially when the target object is food, etc., chemical changes must be avoided.

By separating the electrode and the object with a membrane, this chemical change can be prevented to some extent.

By using a membrane, an electrode chamber is formed and filled with an aqueous solution, but due to the above-mentioned properties, especially when an ion exchange membrane is used, almost no movement of water toward the object occurs.

An example of the configuration of the apparatus used in the present invention will be explained with reference to FIG.

What each symbol indicates in the figure is as follows.

■Anode 2 Cathode 3 Neutral diaphragm 4 Cation exchange membrane 5 Object to be dehydrated 6 Anode chamber 7 Cathode chamber When the object to be dehydrated is a gel with a positive charge, when electricity is applied between the anode and negative electrodes, the main body components undergo cation exchange. The water is drawn to the membrane side (cathode side), the water is drawn to the anode side, a portion of it is drawn into the anode chamber, and most of it drips to the bottom.

When a slight pressure is applied from both sides of the bipolar chamber, the volume of the gel etc. decreases as the water content decreases, and the distance between the negative and positive poles gradually decreases, thus achieving the purpose of dehydration.

Gels or pastes are generally electrically charged, or tend to become electrically charged, and are affected by the electric current in the manner described above.

The gel or paste tends to become electrically charged when it has a weak acid or weak base group. This means that by adding such an acid, the weak acid or weak basic group, respectively, dissociates and becomes electrically charged.

In this way, adjusting the pH and imparting a charge has a very large effect in the present invention.

When the object is a gel, the part 5 in Figure 1 can be the gel itself or the gel in a cloth bag, and generally there is no need to form a chamber, but in the case of a paste, this part is It is necessary to put the paste in it as one chamber.

In the case of a paste, the diaphragm 3 is preferably a semi-permeable membrane that can block water.

In dehydration by electroosmosis using an ion exchange membrane,
Various configurations are possible depending on the properties of the object to be dehydrated.

In other words, there are cases where a cation exchange membrane is used on the cathode side, an anion exchange membrane is used on the anode side, and a cation exchange membrane is used on the cathode side, and an anion exchange membrane is used on the anode side. This falls under the first configuration.

The configuration of the present invention is particularly suitable when the object is anion exchangeable (has a positive charge), and in that case, even if there is no anion exchange membrane on the anode side, the dehydration object itself is electropermeable. Depending on the temperature, water moves toward the anode.

In cases other than the above (for example, when a suitable anion exchange membrane cannot be obtained), a considerable effect can generally be achieved by using only the cation exchange membrane on the cathode side when dehydrating the gel or paste.

In addition, when the target object has no charge, the mechanism is slightly different, but by incorporating an appropriate amount of soluble inorganic salts into the target object,
It is also possible to extract water along with ions by utilizing the electroosmotic properties of ion exchange membranes.

Although the present invention is applicable to inorganic materials, it is particularly useful for dehydrating organic gels or pastes.

For example, dehydration of protein gel or soluble protein paste.

Example 1 In an apparatus similar to that shown in FIG. 1, the cation exchange membrane was a sulfonated copolymer of vinyl acetate and ethylene (exchange capacity: 3.1 meq/gr, water content: 42%, thickness: 0.000 mcm). 05 mm), and a cellophane membrane supported on both sides by nonwoven fabric was used as the anode side diaphragm.

The effective area in each case is 5×5d.

Carbon plates were used for both electrodes, and 5.0% was used for both electrode chamber solutions.
% ammonium sulfate aqueous solution was used.

3% glutaraldehyde was added as a gelling agent to a 6% albumin aqueous solution, and a small amount of diluted hydrochloric acid was further added to perform gelation.

This gel was cut into 5×5×1.2 cIrL3 and inserted between the membranes.

A current of 0.25 amperes (10.5-135 volts) was applied for 30 minutes.

A slight pressure was applied to the gel during energization by lightly tightening the entire structure, including both electrode chambers, with a thin rubber ring.

After energization, the thickness of the gel was 4.5 mm.

[Brief explanation of drawings]

FIG. 1 shows an example of the configuration of an apparatus used in the present invention.

Claims (1)

[Claims] 1. A dehydration method characterized by arranging a cation exchange membrane on the side of the cypress when dehydrating a gel or paste-like material by electroosmosis.