JPS5934437B2 - Mercury separation and removal method using dicyclohexyl-24-crown-8 - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for separating and removing mercury that exhibits an excellent separation effect on mercury.

Mercury ions are contained in waste liquid from mercury-based electrolytic sorter factories, chemical factories that use mercury catalysts, and manufacturing factories for pharmaceuticals and disinfectants that contain mercury.

Since mercury ions, especially mercuric ions, have various adverse effects on the human body, it is stipulated that mercury ions cannot be detected in factory waste fluids, and their complete removal is required.

On the other hand, conventional techniques for treating mercury ion-containing waste liquid include precipitation methods, adsorption methods, and ion exchange methods.

However, the reality is that none of these methods is fully satisfactory for the following reasons.

When using the precipitation method, it is difficult to precipitate if the mercury ions in the waste liquid are dilute, and even if a precipitate is formed, it is troublesome to treat it, and it is difficult to carry out continuous operation. This requires a large amount of chemicals, and there is a risk that new pollution may be caused by the chemicals.

When using the adsorption method, it is difficult to carry out continuous operation, a large amount of adsorbent is required, regeneration and processing are difficult, and furthermore, the adsorbent is worn out and damaged.

When using the ion exchange method, equipment costs and operating costs are high, and economic losses due to wear and damage of the exchange membrane are also large.

In recent years, separation methods using solvent extraction have attracted attention from the viewpoint of energy conservation, and attempts have also been made to apply them to the treatment of waste liquids containing mercury ions.

The solvent extraction method has many advantages such as simple equipment, easy continuous operation, high separation efficiency, and high recovery rate of mercury.

However, extraction reagents are relatively expensive and need to be used in large quantities, and there are many problems such as oil contamination in waste liquid and unavoidable loss of extraction reagents and solvents.

The inventors of the present invention have conducted various studies to solve the above-mentioned problems, and have found that if waste liquid treatment is performed using a liquid membrane containing a specific reagent, the amount of extraction reagent used will be small and recycling can be achieved. The present inventors have discovered that heavy metals can be efficiently separated and removed, and have completed the present invention.

That is, the method of the present invention consists of using a liquid film in which dicyclohexyl-24-crown-8 is dissolved.

A separation operation using a liquid membrane is an operation in which components in a liquid phase or a gas phase (generally called a feed phase) are transferred to another liquid phase or gas phase (generally called a recovery phase) via a liquid membrane.

When a liquid membrane is applied to waste liquid treatment as in the present invention, it becomes a liquid phase-liquid membrane-one liquid phase system, and in this case, the liquid removal method involves performing forward extraction and reverse extraction in a solvent extraction method simultaneously in a single device. It has major advantages not found in conventional separation methods, such as the ability to use only a small amount of extraction reagent and the ability to reuse it.

Dicyclohexyl-24-crown- used in the present invention
8 is represented by the following structural formula; and has the property of selectively taking in and trapping mercury ions.

The liquid film used in the present invention is dicyclohexyl-24-
It is formed from a solution in which Crown-8 is used as a carrier and dissolved in a solvent.

As the solvent, organic solvents such as chloroform and xylene can generally be used.

In the present invention, as a phase for recovering mercury, a solution having a higher chlorine ion concentration than the waste liquid as the feed phase, such as hydrochloric acid or an aqueous sodium chloride solution, is used.

An example of an apparatus and method for carrying out the present invention will be described below with reference to the drawings.

In FIG. 1, A shows a plan view of the reaction tank 10, and B shows a left sectional view of the reaction tank 10.

A partition plate 11 is installed across the center of the reaction tank 10 at an intermediate height from the bottom.

The recovery phase 1 flows through the lower layer from right to left in Figure 1A, and reaches reaction tank 1.
0, some of it is withdrawn, but most of it is recycled and a new recovery phase is replenished.

The feed phase 3 flows in the lower layer from left to right in FIG. 1, but does not mix with the recovery phase 1 because it is partitioned by the partition plate 11.

The liquid film phase 2 enters the upper left part 15 of FIG.
The flow path is changed by the flow path changing plate 12, 12' as shown by the dotted line in the upper layer of 0, flows out from the lower right part 20, and flows into the pump 2.
1 and is circulated with almost no loss.

By operating in this way, when the liquid film comes into surface contact with the waste liquid, dicyclohexyl in the liquid film is removed at the interface.
24-Crown-8 selectively takes in mercuric ions in the waste liquid to form a complex, and the mercuric ions in the waste liquid are extracted into the liquid membrane.

The liquid membrane then comes into surface contact with the recovery phase having a high concentration of chloride ions.

The mercury complex in the liquid film reacts with chloride ions in the recovery phase, releases mercuric ions, and returns to the original carrier.

In this way, mercuric ions in the waste liquid are separated and concentrated in the recovery phase.

In this way, the present invention utilizes dicyclohexyl-24 as a carrier.
- This is a method for separating and removing mercury using a liquid membrane, which takes advantage of the fact that the extraction and distribution of mercuric ions by Crown-8 differs depending on the chlorine ion concentration.

The method of the present invention is constructed as described above, and as compared to the conventional method, the loss of solvent etc. can be reduced to an insignificant level.

That is, dicyclohexyl-624-crown-8 used as a carrier in the present invention is hardly soluble in water, etc., and by selecting a solvent that is difficult to dissolve in water, etc., loss of solvent, etc. can be reduced. It has the advantage of being able to prevent new pollution caused by solvents and the like.

Furthermore, the present invention provides dicyclohexyl-24-crown-8
By taking advantage of the property of selectively taking in and trapping mercury ions, the amount of solvent, etc. to be used can be reduced, and mercury ions can be efficiently separated and removed.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 0.0 as the supply phase (1 phase). OI MHgC1 water bath solution,
0.0 as a liquid film solution (■ phase). A chloroform solution containing OIM dicyclohexyl-24-crown-8, an aqueous IMHC1 solution as the recovery phase (phase ■), and a liquid volume ratio of phase ■:
When treated with ■Phase 2 ■Phase -102 1:1, the mercury concentration in Phase I after treatment decreased to approximately 1/7 of the initial concentration, and the mercury concentration in Phase ■ was approximately 8 times the initial concentration in Phase I. The mercury concentration was approximately 55 times that of the 2 phase after treatment.

Example 2 Example 1 except that 1M NaCl aqueous solution is used as the phase
When treated under exactly the same conditions as , the mercury concentration in the ■ phase after treatment will be approximately 1/6.5 of the initial concentration, and the mercury concentration in the ■ phase will be approximately 1/6.5 of the initial concentration.
The mercury concentration of the phase I was approximately 8 times the initial concentration and approximately 50 times the mercury concentration of the I phase after treatment, giving almost the same treatment results as in the case of the HCI aqueous solution.

Example 3 When treated under exactly the same conditions as in Example 1 except that the liquid volume ratio was set to 1 for phase I: ■phase: ■phase -5:, the mercury concentration in phase I after treatment was approximately 1/14 of the initial concentration. The mercury concentration in the ■phase was approximately 4 times the initial concentration of the I phase, and approximately 60 times the mercury concentration in the I phase after treatment.

Example 4 The concentration of mercury-containing wastewater of phase (1) was 1/10 that of Example 1, that is, 0. When the OOI MHgC12 aqueous solution was used and the other conditions were exactly the same as in Example 1, the mercury concentration in the I phase after treatment decreased to approximately 1/12 of the initial concentration, and the mercury concentration in the The mercury concentration was approximately 8 times the initial concentration, and approximately 100 times the mercury concentration in the ■phase after treatment.

When compared with Example 1, it can be seen that this example, in which the concentration of mercury in the wastewater was lower, was more efficiently separated.

[Brief explanation of drawings]

FIG. 1 shows an example of an apparatus and method for carrying out the invention. 1...Recovery phase, 2...Liquid film phase, 3.
...Feed phase, 10...Reaction tank, 11...
...Partition plate, 12.12'...Flow path change plate, 13.21...Pump.

Claims (1)

[Claims] 1. A mercury separation and removal method characterized in that a liquid membrane in which dicyclohexyl-24-crown-8 is dissolved is used to separate and remove mercuric ions from a mercury-containing waste liquid.