JPH04126524A - Diffusion dialysis - Google Patents

Abstract

PURPOSE:To effectively prevent generation of mold without cleaning the dialysis apparatus by disassembling, by incorporating an antimold agent comprising 1,2-benzisothiazolin-3-one into the liquid to be used for diffusion dialysis or to the recovery water. CONSTITUTION:An antimold agent comprising 1, 2-benzisothiazolin-3-one is incorporated into the liquid to be used for diffusion dialysis or into the recovery water. It is necessary to consider such problems for the antimold agent as the influence on the ion exchange membrane, residual amt. of the agent in the recovered acid, or influence of the agent itself on human body, etc. Therefore, the antimold agent is preferably used in the form of soln. or compounded mixture of ethylenediamine, dipropylene glycol, propyleneglycol, or triazine, and the antimold agent is incorporated by 0.1-100ppm. Thereby, generation of mold is effectively prevented without overhaul cleaning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a diffusion dialysis method, particularly a diffusion dialysis method that prevents the growth of mold.

[Prior Art] Diffusion dialysis using an anion exchange membrane has been widely put into practical use for acid recovery.

In this case, especially when attempting to recover sulfuric acid, mold grows and grows on the surface of the anion exchange membrane. In order to prevent this, measures are taken such as sterilizing the diffused dialysate and/or recovered water in advance using ultraviolet sterilization equipment, or periodically filling the dialysis fluid with formalin solution.

[Problems to be solved by the invention] However, ultraviolet sterilization is temporary and has no effect on mold that invades afterward, and periodic sterilization with formalin solution has a relatively weak effect, and This is not the preferred method as it causes problems such as odor and drainage.

Currently, ion exchange membranes contaminated with mold are removed by disassembly and cleaning.This disassembly and cleaning not only requires a great deal of labor and time, but also causes artificial damage to the ion exchange membrane. It has the fatal disadvantage of causing serious damage and shortening the life of the ion exchange membrane.

[Means for Solving the Problems] In view of the above, the inventor of the present invention has conducted various research and examinations with the aim of effectively preventing the growth of mold (without disassembling and cleaning it). It has been found that the above object can be achieved by the presence of 1,2-benzisothiazolin-3-one in the dialysate and/or the recovery water, and this is the gist of the present invention.

In the present invention, the influence of the antifungal agent on the ion exchange membrane, the problem of remaining in the recovered acid, the influence of the antifungal agent itself on the human body, etc. must be taken into consideration. For this reason, the antifungal agents used are ethylenediamine, dipropylene glycol,
It is suitable to use aqueous solutions or blended mixtures of propylene glycol, triazine.

If the amount of the antifungal agent used in the present invention is too large, a large amount will remain in the recovered liquid, impairing the purity of the recovered liquid, and if it is too small, the effect will be insufficient, both of which are undesirable. . For this reason, it is appropriate to adopt an amount of about 0.11-100 ppm, preferably about 1-10 ppm. In actual use, it is sufficient to simply add a predetermined amount of these antifungal agents to the water for recovery, but during diffusion dialysis, it is preferable to also apply an antifungal agent and ultraviolet sterilization to the dialysate fluid supplied. The fluid to be dialysed can be appropriately used for recovering acids such as sulfuric acid, recovering alkalis, and the like.

[Example] Asahi Glass F-O incorporating 100 anion exchange membranes
Two W-type diffusion dialysis tanks were prepared, and sulfuric acid recovery from a stock solution of 300 g/12 sulfuric acid and 120 g/β aluminum sulfate was performed according to a conventional method. The water for use and recovery in the two units uses ion-exchanged pure water, and is preheated using an ultraviolet sterilizer 5H manufactured by Chiyoda Kohan ■.
- Sterilization was performed by ID.

Further, 3 p of an ethylenediamine aqueous solution of 1,2-benzisothiazolin-3-one (active ingredient concentration 33%) was added to the recovery water of one diffusion dialysis tank and the dialysate.
pm was added continuously. The supply flow rate is the same, and the stock solution is 5.
．． 07β/hour, water for recovery is 5. Oj2/hour. Initially, the sulfuric acid recovery rate was 82% in both cases, but in the case where ion-exchanged water with only ultraviolet rays was used, the recovery rate gradually decreased after one month and dropped to 68% after four months.

On the other hand, the one to which 1,2-benzisothiazolin-3-one was added maintained a stable sulfuric acid recovery rate and
After several months, the value remained at 82%. At this point, a disassembly and inspection was conducted, and it was found that approximately 30% of the upper part of the recovery acid chamber was using an ion-exchange membrane that sterilized only with ultraviolet light.
There was a large amount of filamentous mold growing. No abnormality was found in the sample to which 1,2-benzisothiazolin-3-one was added.

Claims (1)

[Scope of Claims] 1. A diffusion dialysis method characterized in that an antifungal agent consisting of 1,2-benzisothiazolin-3-one is present in the dialysate to be diffused and/or in the water for recovery. 2. The diffusion dialysis method according to claim 1, wherein the fungicide is an aqueous solution or a blended mixture of ethylenediamine, dipropylene glycol, propylene glycol, and triazine. 3. The diffusion dialysis method according to claim 1, wherein the antifungal agent is present in an amount of 0.1 to 100 ppm.