JPH05140775A - Method for regenerating ethanol for dewatering in degreasing and cleaning - Google Patents

Abstract

PURPOSE:To obtain regenerated concd. ethanol by treating a mixture of water and ethanol produced when a material to be cleaned is degreased, cleaned, washed and then dipped in ethanol and the cleaning water is removed with a specified water separation membrane. CONSTITUTION:A material to be cleaned is deacidified and cleaned in a alkali cleaning tank 1 contg. an aq. soln. of alkali cleaning agent and an aq. soln. of surfactant, and then passed through a cold water washing tank 2 and a hot water washing tank 3 to wash away the alkali degreasing and cleaning soln. The material is dipped in a dewatering tank 4 contg. ethanol to rapidly remove the cleaning water deposited on the material, the material is then rapidly dried by a hot-air drier 5, and the rusting due to incomplete drying is perfectly prevented. Since the ethanol used for dewatering has a high content of water, the ethanol is sucked by a pump 6 and a pressure reducing device 8 into a water separation tank 7 provided with a water separation membrane such as a polyimide org. membrane to separate and remove the water from ethanol, and the ethanol is recovered as the concd. ethanol excellent in dewatering capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating ethanol used for draining in degreasing cleaning using an aqueous alkaline detergent solution and / or an aqueous surfactant solution.

[0002]

2. Description of the Related Art In degreasing and cleaning using an aqueous alkaline detergent solution and / or an aqueous surfactant solution, in order to prevent rust during the water rinsing step and the drying step, it is dipped in ethanol from the viewpoint that it can be drained or dried at a low temperature. However, the method of reducing the water adhering to the product is generally performed.

However, since ethanol and water are completely compatible with each other, the drainage rate decreases when the amount of water in ethanol increases, so that the water is decomposed by distillation and ethanol is reused.

[0004]

However, since ethanol and water form an azeotrope, 96 w is obtained by distillation.
Ethanol above t% cannot be regenerated. It is advantageous to use a high concentration of ethanol in order to improve the draining efficiency and the drying rate and prevent the generation of product.

In view of the above-mentioned state of the art, the present invention is to provide a method capable of regenerating ethanol used for draining into high-concentration ethanol in degreasing cleaning using an aqueous alkaline detergent solution and / or an aqueous surfactant solution. is there.

[0006]

Means for Solving the Problems The present invention is directed to a degreasing and washing step using an aqueous alkaline detergent solution and / or an aqueous surfactant solution, a water rinsing step, a draining step by immersion in ethanol,
In the degreasing and washing method consisting of a drying step, a mixed solution of ethanol and water from the draining step by immersion in ethanol is continuously extracted, and ethanol is obtained by separating and removing water through a separation membrane that selectively separates water. The method is a method for regenerating draining ethanol in degreasing cleaning, which comprises returning to the draining step by immersion in ethanol.

[0007]

The separation membrane of the present invention that selectively separates water is a membrane that allows only water to permeate and does not allow ethanol to pass, and can separate even at concentrations that cannot be separated by distillation.

The following are examples of water separation membranes applicable to the present invention. (1) Polyimide-based organic film A hollow fiber film having a heat resistant temperature of about 140 ° C. Selection / separation is performed depending on the difference in the dissolution rate into the membrane and the diffusion rate within the membrane. (2) Silica gel type inorganic film A tubular type, which has a heat resistant temperature of about 450 ° C. Water is selectively adsorbed on the -OH group on the membrane surface, condensed in the capillaries on the membrane surface, and then evaporated from the permeate side.

In the water rinsing step which is a prerequisite of the present invention, it is generally preferable that the hot water rinsing step is performed after the cold water rinsing step.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. 1
Is an alkaline washing tank, 2 is a cold water rinsing tank, 3 is a hot water rinsing tank, 4 is an ethanol immersion draining tank, 5 is a hot air drying furnace, and 6, 7 and 8 are ethanol-water by the water separation membrane of the present invention. The pump, the water separation membrane tank, and the decompression device which comprise the apparatus which removes water from a mixed solution and regenerates ethanol are shown. Hereinafter, the regeneration characteristics of ethanol using a water separation membrane will be specifically shown.

(Example 1) A silica gel-based inorganic separation membrane manufactured by the following method was used, and degreasing wash water was separated using the apparatus shown in FIG.

(A) Manufacture of silica gel-based inorganic separation membrane Ceramic tube manufactured by NGK Insulators Ltd. (average pore size 0.5 μm)
m, outer diameter 10 mm, length 250 mm) was used as a substrate, and a separation membrane was produced by the following treatment. (1) Preparation of silica sol The chemicals having the compositions shown in Table 1 were placed in a beaker and rapidly stirred and mixed with a stirrer at room temperature. 80 ° C with continuous stirring
When heated to (boiling state), boiling starts due to hydrolysis. After boiling for 25 minutes, cool with tap water from the outside of the beaker. In this state, silica sol is a slightly viscous liquid.

[Table 1] (2) Method of supporting silica sol The ceramics tube was immersed in the silica sol to support the silica sol on the wall of the porous tube. The porous body was placed in an electric furnace and heated at a heating rate of 10 ° C for 5
The temperature was raised to 00 ° C., the temperature was maintained for 10 minutes, the firing was performed, and then the temperature was lowered to room temperature. The above operations 1 to 4 were repeated 4 times.

(B) Separation Experiment A separation experiment of degreasing wash water was conducted using the apparatus shown in FIG. 2 using the silica gel type inorganic separation membrane manufactured by the above method. (1) Feeding material Ethanol aqueous solution, liquid temperature 50 ° C. (2) Pressure Feeding liquid: 1 ata, permeate side: 15 Torr (3) Results Table 2 shows the results after 1 hour of operation.

[Table 2]

(Example 2) A separation experiment of a degreasing cleaning water was carried out by using a polyimide organic film as a separation membrane and using the apparatus shown in FIG. (1) Separation Membrane Specifications Hollow Fiber Membrane Module Dimension: 20φ × 300 L (mm) (2) Feed Raw Material Ethanol Aqueous Solution, Liquid Temperature 60 ° C. (3) Pressure Feed Liquid: 1ata, Permeate Side: 10 Torr (4) Results Table 3 The result after 1 hour operation is shown.

[Table 3]

[0015]

EFFECTS OF THE INVENTION According to the present invention, since water can be drained at an ethanol concentration of 96 wt% or more, which cannot be separated by distillation, and water can be drained at a constant concentration of ethanol, the water draining and drying time becomes constant, and a problem due to poor drying occurs. Rust can be completely prevented, and the separation of water by a water separation membrane has a faster water separation rate and a much smaller energy than the distillation method of evaporating and condensing and recovering the ethanol component. It has great industrial and economic value.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention

FIG. 2 is a schematic view of a device for separating water in ethanol used in the examples of the present invention.

Claims (1)

[Claims] 1. A degreasing and washing method comprising a degreasing and washing step using an aqueous alkaline detergent solution and / or an aqueous solution of a surfactant, a water rinsing step, a draining step by immersion in ethanol, and a drying step, wherein ethanol and water from the draining step by immersion in ethanol are used. For removing water in degreasing cleaning, which is characterized in that a mixed solution of and is continuously extracted, water is separated and removed through a separation membrane that selectively separates water, and this is returned to the water removing step by immersion in ethanol. How to regenerate ethanol.