JPH04193333A - Detergent for oil contaminated membrane - Google Patents

Abstract

PURPOSE:To effectively remove contaminants such as oil from a membrane and to restore the separating performance by using a detergent contg. specified aliphatic satd. alcohol or further contg. alkali and an anionic surfactant. CONSTITUTION:A detergent contg. 3 or 4C aliphatic satd. alcohol such as n- propylalcohol or n-butyl alcohol as an essential component or further contg. alkali such as NaOH and/or an anionic surfactant such as fatty acid soap is used in the form of a uniform soln. or emulsion when a separating membrane with adsorbed oil such as an ultrafiltration membrane is washed. This detergent is especially fit to wash a membrane contaminated by treating waste liquor contg. water-soluble lubricating oil. Contaminants are effectively removed from the membrane and the separating performance of the membrane can be restored.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a novel cleaning agent for oil-contaminated films, more specifically,
For example, for oil-contaminated membranes that effectively remove oil and other contaminants that have permeated separation membranes such as ultrafiltration membranes used in water-soluble lubricating oil waste treatment, etc., and restore the membrane's separation performance. It relates to cleaning agents.

[Prior art] In recent years, since water-soluble lubricants are nonflammable and inexpensive, they have been used as cutting and grinding oils for metals whose cooling effect is an important function, as well as cold rolling lubricants and hot rolling lubricants. It is widely used as a lubricant. This water-soluble lubricant includes, for example, mineral oil, synthetic oil, extreme pressure additives, surfactants,
It is prepared by appropriately mixing a rust preventive agent, an antioxidant, an antifoaming agent, a preservative/antifungal agent, etc. depending on the purpose, and is usually diluted with water to about 10 to 100 times and used as a so-called coolant.

The water-soluble lubricating oil is usually obtained by separating and recovering the oil from the waste liquid after use and reusing the recovered oil, and a separation membrane such as an ultrafiltration membrane is used to recover the core part. Often used. When a separation membrane is used to recover oil from such waste liquid, oil and other substances permeate the separation membrane, resulting in
Separation performance of the membrane may be drastically reduced.

By the way, when the separation performance of a separation membrane is degraded due to contamination, methods for restoring the performance vary depending on the membrane shape, the liquid to be treated, etc., but various methods can be used, such as mechanical scrubbing with a sponge ball, A method in which the contaminated layer on the membrane surface is removed by flowing the liquid at a high flow rate and using the turbulent flow of the liquid. After pressurized operation for a certain period of time, the pressure is released and the membrane surface is removed by backflow from the outside of the separation membrane to the inside due to the osmotic pressure of the liquid. A method of lifting the contaminant layer formed on the top and removing it by a flow of liquid;
Furthermore, an alkaline agent (Japanese Unexamined Patent Publication No. 50-75177)
Methods using cleaning chemicals such as surfactants and surfactants (Japanese Unexamined Patent Publication No. 51-63375) have been adopted.

Among these methods, in order to recover the performance of the separation membrane used to separate and recover oil from water-soluble lubricating oil waste, it is necessary to remove oil that has penetrated into the membrane, so cleaning chemicals are used. It is thought that the method used is effective. However, even if ordinary cleaning chemicals such as the above-mentioned alkaline agents and surfactants are used, there is a problem in that the permeated oil is insufficiently removed and the separation performance of the membrane cannot be sufficiently restored.

On the other hand, a method using propyl alcohol as a cleaning agent for membranes for producing ultrapure water has been proposed (Japanese Patent Laid-Open No. 61-25
No. 4805), which is completely different from the object of the present invention.

[Problems to be Solved by the Invention] The present invention effectively removes contaminants such as oil that have permeated a separation membrane such as an ultrafiltration membrane used for treating water-soluble lubricating oil waste liquid, The purpose of this invention is to provide a cleaning agent for oil-contaminated membranes to restore the separation performance of the membrane.

[Means for Solving the Problems] As a result of intensive research to develop a cleaning agent for oil-contaminated membranes having such favorable properties, the present inventor has found that a specific aliphatic saturated alcohol and, in some cases, an alkali or anion The inventors have discovered that the above object can be achieved by using a cleaning agent containing a surfactant, and have completed the present invention based on this knowledge.

That is, the present invention provides a cleaning agent for oil-contaminated films containing at least one selected from aliphatic saturated alcohols having 3 and 4 carbon atoms and optionally an alkali and/or anionic surfactant. It provides:

The present invention will be explained in detail below.

The aliphatic saturated alcohol used as an essential component in the cleaning agent of the present invention must have 3 or 4 carbon atoms, such as low propyl alcohol,
Isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 5ec-butyl alcohol and t-
Butyl alcohol is mentioned. These alcohols may be used alone or in combination of two or more. Those with a carbon number of 5 or more are difficult to dissolve in water and have poor membrane permeability, making it impossible to remove contaminants such as oil sufficiently, while those with a carbon number of 2 or less have a poor affinity for oil and are Insufficient removal of contaminants.

The concentration of the aliphatic saturated alcohol in the cleaning agent of the present invention is not particularly limited, and is appropriately selected depending on the type of membrane to which it is applied.

The cleaning agent of the present invention may optionally contain an alkali and/or anionic surfactant along with the aliphatic saturated alcohol. Examples of the alkali include alkali metal hydroxides, carbonates, and bicarbonates such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Sodium oxide is used. These alkalis may be used alone or in combination of two or more.

The alkali has a saponification effect on oil, and the cleaning agent containing the aliphatic saturated alcohol and alkali can efficiently remove the oil that has penetrated the membrane due to their synergistic effect.

Regarding the alkali concentration in the cleaning agent, when using sodium hydroxide as the alkali, it is usually 0.05 to 10.
% by weight, preferably in the range of 0.5 to 2% by weight.

On the other hand, examples of anionic surfactants include fatty acid soaps, alkyl ether carboxylates, alkylaryl sulfonates, α-olefin sulfonates, higher alcohol sulfate ester salts, alkyl ether sulfates,
polyoxyethylene alkyl phenyl ether sulfate,
Examples include alkyl ether phosphate ester salts and alkyl phosphate ester salts. These may be used alone or in combination of two or more.

These surfactants have a micellar effect on oil, and a cleaning agent containing the surfactant and aliphatic saturated alcohol can efficiently remove oil that has penetrated the membrane due to their synergistic effect. I can do it.

There is no particular restriction on the concentration of the anionic surfactant in the cleaning agent, and it can be appropriately selected depending on the conditions of use.

The cleaning agent of the present invention is preferably a homogeneous solution, but may be an emulsion. In addition, the membrane to which the cleaning agent can be applied is not particularly limited as long as it is a membrane that adsorbs oil. For example, it can be applied to ultrafiltration membranes, microfiltration membranes, reverse osmosis membranes, etc. that adsorb oil. can. In particular, it is suitably used to remove contaminants such as oil that have permeated separation membranes used in water-soluble lubricating oil waste treatment.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Examples 1 to 4, Comparative Examples 1 to 4 A cleaning agent having the composition shown in Table 1 was prepared, and this cleaning agent 500
An ultrafiltration membrane (manufactured by Polyolefin, molecular weight cut off: 20,000) treated with coolant wastewater was immersed in m1 for 24 hours, and after washing with pure water, its pure water flux was measured. The results are shown in Table 1.

In addition, the ultrafiltration membrane that treated the coolant wastewater has brownish oil permeating to the inside of the membrane, and the pure water flux of this contaminated membrane is 1 kg/cm and 0.05 m3/m at 2.25°C. ”-day.By the way, it was 1.6 when it was new.

(The following is a blank space) [Effects of the Invention] The cleaning agent for oil-contaminated films of the present invention contains a specific aliphatic saturated alcohol and optionally an alkali and/or anionic surfactant, and is capable of removing oil and other substances. It is used to remove contaminants from ultrafiltration membranes, microfiltration membranes, reverse osmosis membranes, etc. into which contaminants have penetrated, thereby restoring the separation performance of the membranes. It is particularly suitable for use on contaminated films used in water-soluble lubricating oil waste treatment.

Claims (1)

[Scope of Claims] 1. A cleaning agent for oil-contaminated films, comprising at least one selected from aliphatic saturated alcohols having 3 and 4 carbon atoms. 2. A cleaning agent for oil-contaminated films containing at least one selected from aliphatic saturated alcohols having 3 and 4 carbon atoms and an alkali and/or anionic surfactant.