JPS5980387A - Reverse osmosis treatment of waste water used for washing electronic part with semipermeable composite membrane - Google Patents

Abstract

PURPOSE:To obtain permeating water of high purity, by treating waste water used for washing electronic parts after being subjected to oxidizing and reducing treatments with the semipermeable composite membrane of a cross-linking polymer containing furfuryl alcohol as a main component on a porous supporting body. CONSTITUTION:Waste water used for washing electronic parts, e.g. water discharged from the process of etching semiconductor bodies, the process of dulling Braun tubes, etc., is subjected to oxidizing and reducing treatments. As a means for said oxidizing treatment, a method for oxidatively decomposing the waste water by applying ultraviolet rays of 400Nm to it in the presence of chlorine or hydrogen peroxide may be adopted. A reducing agent for said reducing treatment may be sodium sulfite, sodium sulfide or the like. After said treatments are completed, the waste water is treated with a cross-linking semipermeable composite membrane in which the semipermeable membrane layer of a cross-linking polymer containing furfuryl alcohol as a main component is provided on a porous supporting body. Thus, the quality of permeating water can be purified to a high degree.

Description

DETAILED DESCRIPTION OF THE INVENTION Mokkomei relates to a method for reverse osmosis treatment of electronic component cleaning wastewater using a semipermeable composite membrane.

More specifically, it relates to a method for reverse osmosis treatment of electronic component cleaning wastewater using a crosslinked semipermeable composite membrane in which a semipermeable thin film layer of a crosslinkable polymer containing furfuryl alcohol as a main component is provided on a porous support. It is.

Ultrapure water is used to clean electronic parts, but
It is more advantageous to produce ultrapure water from water used for cleaning (hereinafter referred to as electronic parts cleaning waste water) than from general water such as city water in terms of effective use of resources and production costs. be.

For this reason, the wastewater is treated using methods such as reverse osmosis, but recently it has become common to use semipermeable composite membranes, which have a superior rejection rate compared to semipermeable asymmetric membranes. It is becoming.

However, even when this semipermeable composite membrane is used, it has the disadvantage that the rejection rate decreases due to membrane contamination relatively quickly, and this hinders the reduction of processing costs. This is the reality.

Note that the closer the permeated water obtained by reverse osmosis treatment to the wastewater is to ultra-pure water, the easier it is to convert it into ultra-pure water in the post-treatment process, Polylasha. It is difficult to obtain permeated water that is extremely close to ultrapure water using a method that performs reverse osmosis treatment using a semipermeable composite membrane after precision filtration of wastewater, and there is still room for improvement in this respect. ] is based on these conventional problems.
What is its purpose?

It is an object of the present invention to provide a method for reverse osmosis treatment of wastewater from washing electronic parts using a semipermeable composite membrane, which can prevent a reduction in rejection rate due to membrane contamination over a long period of time, and can obtain permeated water of higher purity.

A method for reverse osmosis treatment of electronic component cleaning wastewater using a semipermeable composite membrane according to the present invention achieves this objective.

"Porous Support" - A method for reverse osmosis treatment of electronic component cleaning wastewater using a cross-linked semipermeable composite membrane provided with a crosslinkable TJ polymer semipermeable thin film layer containing niflufuryl alcohol as a main component, in which the wastewater is This method is characterized by performing oxidation treatment and reduction treatment in the pretreatment step.

Electronic component cleaning wastewater in the present invention refers to used water discharged from a semiconductor etching process or a cathode ray tube matting process.

This water contains various organic and inorganic substances.
Generally, it is acidic with a pH of 4 or less. Regarding the details of the contained substances, as fluorine ions, 2
00 ppm or less, 500% as other metal ions
ppm + organic matter is C0I) 50 p p as c+ value
Generally, it is less than m.

In the present invention, electronic component cleaning wastewater containing low molecular weight organic substances such as monosodium fluoride, calcium, lower alcohols, and halogenated hydrocarbons is converted into a semipermeable furfuryl alcohol based wastewater. Reverse osmosis treatment is performed using a composite membrane, or at this time, the wastewater is oxidized and reduced in the pretreatment process. This makes it possible to prevent a decline in the rejection rate due to membrane contamination over a long period of time, and also to reduce the The quality of permeated water can be improved to a higher degree of purity, and treatment costs can be reduced.

The composite membrane used in this reverse osmosis treatment is one in which a semipermeable thin film layer of a crosslinkable polymer whose main component is Fluf IJ) real alcohol is provided on a porous support.
This semipermeable composite membrane is covered by U.S. Patent No. 2) 926,798.
No. IJJ +Y (disclosed to II man etc., and...
11 plate types, 1 cylindrical type, and spiral type.

Are there various types of hollow child types?

Any type of misfire I may be used.

Examples of the porous support include notebook materials such as polysulfone and polyacrylonitrile having a thickness of 20 μm to 1/l, and these have 20× to 100 holes (one or more holes).

The oxidation treatment in the 10,000+ l-1iJ treatment process is carried out to detoxify and detoxify substances that reduce the selective separation ability over time and substances with low selective separation contained in the wastewater. The specific method is as follows: 4
Oxidative decomposition method by irradiation with 0ONm ultraviolet rays in the presence of chlorine or hydrogen peroxide, oxidative decomposition method using ozone, oxidizing agent such as sodium hypochlorite or hydrogen peroxide using iron salt or nickel salt as a catalyst. Examples include methods of oxidative decomposition.

Then, the electronic parts cleaning wastewater is oxidized by a method selected from among these various methods, and the remaining organic substances have a C0Dcr value of 1ot) I) 111 or less.

Preferably it is treated at 3 ppm.

Next, this acid-treated water is further reduced. l! Alternatively, this reduction treatment is carried out in order to increase the separation ability of the furfuryl alcohol-based semipermeable composite membrane, especially the separation ability of fluorine ions, and to maintain its high rejection rate constant for a long time or a long period of time. Here, Q is used as a reducing agent.

Sodium sulfite, sodium bisulfite, i+ town sulfuric acid scum.

It is preferable to add a plurality of these, and the amount of addition is such that the oxidizing agent added in the acid and arsenic treatment is completely erased.

In addition, an appropriate amount of the reducing agent added here remains in the system, that is, an appropriate amount is added so as to create a reducing atmosphere. Generally, when expressed in terms of redox potential, ]00mV to 200
It is sufficient to add the oxidizing agent so that the amount of the oxidizing agent becomes 7 MV, and the oxidizing agent is not limited to this, and can be appropriately selected depending on the type and size of the oxidizing agent contained, the type of reducing agent used, etc.

Note that if added in excess, the separation ability of fluorine ions will be adversely reduced, so sufficient care must be taken when adding this.

When electronic component cleaning wastewater is oxidized, then reduced, and then subjected to reverse osmosis treatment, it generally produces O, l pp as fluorine ions, although there are some differences depending on the quality of the wastewater.
m or less, electrical conductivity is 1 μs/- or less + CoI) Cr
Permeated water with a value of Lppm or less can be obtained.

This fc7 permeated water is of high purity.

It is close to so-called ultra-pure water, and by post-processing it, it is easy to obtain ultra-pure water that can be used for cleaning electronic parts, making effective use of water resources and reducing the cost of producing ultra-pure water. It is possible to try to reduce the

In addition, when performing reverse osmosis treatment of electronic component cleaning wastewater that has been oxidized and reduced in the pre-treatment process using a furfuryl alcohol-based semipermeable composite membrane, the 1j11 wastewater must be treated at 10K! 7/m
~9/crl to 100, preferably 30 KVAv
It is sufficient to supply it under pressure to t ~ 60 K'//ci,
The operating conditions such as this /JO pressure juice or water temperature are 1 liter.
It can be set in the same way for every general occasion.

Hereinafter, the non-invention will be explained more specifically based on Examples and Comparative Examples.

Example 1 F- or 117 ppm, NH; l- or 7Q ppm
, Na61) 1ml, CI-151)l
) In, electrical conductivity 480 μS/cm, C0
DC' or 81) PIYI PH or 3.2 Cleaning waste water from half-shaped body etching jig E or C12 for 30 yen)
! In the presence of 11, Sho Pressure Mercury Strike (manufactured by Kushio Ichigeki Co., Ltd.)
Oxidation treatment was performed by irradiating with 0.5 l\WAn'.

The oxidation-reduction potential of the obtained water was 600 mV.

Next, 100 ppm of sodium sulfite was added and mixed to adjust the redox potential to 110y7LV. This was pressurized to 50 kg/m and treated with a flat membrane reverse osmosis tester (membrane area 32.15 crl) at a water temperature of 25°C.The amount of permeated water and the quality of the permeated water are shown in Table 1. It became like this.

The reverse osmosis membrane used in the tester is a semipermeable composite film in which a porous polysulfone membrane is placed on a support and a semipermeable thin film layer of a cross-linked polyfurfuryl alcohol vehicle is provided on top of the porous polysulfone membrane. Produced by the method described in No. 3,926,798.

A polyester fiber with a thickness of 160μ was placed on a glass plate, and 15% dimethylformamide (DMF) of polysulfone (Union Car Co., Ltd., Udel P 3500) was poured onto it. , after spreading it evenly with a 178μ applicator, apply 2%-I) MF.
A porous polysulfone membrane (support) was prepared by soaking it in an aqueous solution containing 0.05% sodium dotecyl sulfate, and thoroughly washing with water. Alcohol 2%, sulfuric acid 2%, isoflovir alcohol 20%, dotecyl sulfate soda 0.6
7' Aqueous solution t1k containing X was poured into the chamber 11]1^ and held vertically for 1 minute.

It was heated in an oven at 150'C for 15 minutes, and then a black semipermeable composite membrane with a transparent surface was obtained from the glass plate.

In addition, the separation performance of this composite membrane was as follows: +3.5wt% - When a saline solution was treated at 25°C with 56 kg of water, the separation performance of the composite membrane was as follows:
The division ratio is 99.6%, the amount of permeated water is 0.31 nt/-・1
"Met.

Table 1 Comparative Example 1 When the same cleaning wastewater as that of Example 1 was directly supplied to a reverse I permeation test without oxidation treatment or reduction treatment, the amount of permeated water and the water quality of the permeated water were as shown in Table 1. It became like 2.

Note that the reverse osmosis membrane of the sample TAm and its operating conditions were the same as in Example 1.

Table 2 As is clear from this, washing 1 + waste water 1ii
J% In Comparative Example 1, in which oxidation treatment and reduction treatment were not performed in the physical process, the quality of the permeated water deteriorated as the operation (treatment) time elapsed. U degree, C
While 0DCI- increases, in Example 1, it does not change and remains constant.

It can also be seen that the value of 6 is one step closer to ultrapure water than the value of Comparative Example 1.

Comparative Example 2 The reverse osmosis membrane was a semipermeable composite membrane in which a porous polysulfone membrane was used as a support and a semipermeable thin film layer of a crosslinkable polymer containing polyethyleneimine as a product was provided on the support. When treated under the same conditions as in Example 1, the quality of permeation 4 (old and permeation 11 (C')) was as shown in Table 3.

The above composite membrane is disclosed in Japanese Patent Application Laid-Open No. 49-133282. 1Q
It was produced according to the method described in It. i.e. thickness 1
Polyester fiber with a tit of 1μ is placed on a glass plate.
＋“Shi.

Add polysulfone (Udel manufactured by Union Carbide) to this.
After pouring a 15% dimethylformamide solution of P-3500 and spreading it evenly with a 178μ applicator, immerse it in the solution containing 2% DMF (dimethylformamide) and 05% sodium dobnol sulfate, and then apply it with water. A well-washed polyester fiber-reinforced porous polysulfone membrane (support) was produced.

Next, this polysulfone membrane was coated with polyenalenimine (Ebonon I manufactured by Kuchiki Shokubai Kagaku Co., Ltd.)-]OIll) 0.2
Apply a 5% water/methanol (%) solution evenly.

-t and this base material i2.4-)
(D After immersing in a 1 wt% n-xane solution for 1 minute, the substrate was pulled up to volatilize the n-xane adhering to the film surface, and then heat-treated for 10 minutes at 110 °C.゛1′- having a crosslinkable polyethyleneimine layer
A permeable composite membrane was obtained.

The separation performance of this peritoneal membrane is as follows: 0.1% saline at 25%
When treated at 56 Ky/ci, the salt rejection rate was 99.1% and the permeation rate was 0.31 nl'An
'It was day.

Table 3 From this, as shown in Figure 11, in Comparative Example 2, the quality of the permeated water deteriorated over time.

Moreover, the value is even closer to that of non-ultrapure water than the value of Example 1. Therefore, it is possible that the above-mentioned effects of the present invention cannot be obtained even if an ethyleneimine-based semipermeable composite membrane is used. Recognize.

Comparative Example 3 Reverse osmosis membrane The conditions were the same as in Example 1, except that an asymmetric membrane made of cotton I-acid cellulose was used, and one of the type 5C-1100 manufactured by Maishiki Company was used. [After treatment, the quality of the permeate water h1 and permeate water was as shown in Table 4.

Table 4 As is clear from the above, there are four points that, as in the case of Comparative Example 2, the above-mentioned uninvented effects cannot be obtained even if an asymmetric membrane is used.

As detailed above, the invention is able to prevent the reduction in rejection rate due to temporary contamination over a long period of time, and to obtain permeated water of higher purity, the semi-permeable composite membrane can be used to clean electronic parts waste water. A reverse osmosis treatment method is obtained.

Patent applicant: Higashi Enoshinino' Rinogu Co., Ltd. d.

Claims (1)

[Claims] (1) In the method for reverse osmosis treatment of electronic parts cleaning wastewater using a crosslinked semipermeable composite membrane in which a semipermeable thin film layer of a crosslinkable polymer containing furfuryl alcohol as a main component is provided on a porous support, A method for reverse osmosis treatment of electronic component cleaning wastewater using a semipermeable composite membrane, characterized in that the wastewater is subjected to oxidation treatment and reduction treatment in a pretreatment step.