JPS6112729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oil-water separation filter, and more particularly, to an improved oil-water separation filter for efficiently separating oil from oil-containing water. Conventionally, regarding the removal of water from oil, oil refining,
It is being widely studied in fields such as edible oil refining, various solvent production, and paint production. In addition, for oil-containing wastewater treatment or large-scale oil recovery from dispersed oil-containing water, gravity type, oil collection agent, collection material, oil gelling agent, or sedimentation agent is used in oil refining, tanker ballast, marine oil spill countermeasures, etc. Treatment methods such as oil fences and oil fences are being considered. Furthermore, regarding small-scale wastewater treatment, foam method, electrolytic method, adsorption method,
Various measures have been proposed, including legal restrictions. Then,
The effectiveness of the method using a filter, which is relatively inexpensive and simple, has been pointed out for quite some time and has a long history. However, cloth, nonwoven fabric, foam, etc. that have been considered as conventional filters have serious problems such as rapid deterioration of overefficiency due to oil adhesion and oil leakage due to this. In other words, synthetic fibers such as polyolefin, polyester, acrylic, and polyamide as filter materials are mostly used as collection materials in a broad sense, and when used as filters for oil/water separation, they tend to cause oil adhesion and overefficiency. This causes a rapid decline in As a result of various studies and examinations based on recognition of the above-mentioned problems, the present inventor has developed a specific oil-water separation method that has a water-permeable water-absorbing function mainly based on a water-insoluble hydrogel layer and an oil-repellent function due to occluded water. It has been found that the object can be smoothly and advantageously achieved by forming a function on the surface of the porous sheet and/or the surface of the liquid passage. That is, water-soluble water absorption (water content)
Focusing on the phenomenon that oil does not easily adhere to gel bodies such as konnyaku and agar, and even if oil does adhere to them, the oil will come off by itself when immersed in water. By providing
It has been discovered that it is possible to create a filter that causes less oil adhesion during oil-water separation and is capable of removing oil by itself even if it does adhere. Thus, the present invention has been completed based on the above findings, and includes an oil/water separation filter made of a porous sheet in which water is applied to the surface portion of the porous sheet that is to be brought into contact with oil and water and/or the surface portion of the liquid passage. The present invention provides a novel oil-water separation filter characterized by forming an oil-water separation functional layer having a water-permeable water-absorbing function mainly composed of an insoluble water-absorbing gel layer and an oil-repellent function due to occluded water. According to the present invention, various synthetic fibers, inorganic fibers, natural fibers, natural pulp, synthetic pulp, etc. can be used as filter materials. As mentioned above, such materials have a tendency to absorb oil, but due to the formation of a water-insoluble water-absorbing gel layer that has no affinity for oil,
The foothold for oil to adhere to the filter is coated,
Even if oil adheres to the exposed part of the filter material, as the oil droplets grow, they will be affected by the detachment of the water-containing gel layer, and if the filter is in water, the grown oil droplets will be absorbed by their own buoyancy. It detaches from the filter surface. Thus, according to the filter of the present invention, there is no oil adhesion and no decrease in overefficiency is observed in oil/water separation. In addition, the specific water-absorbing gel layer improves the selective permeation of water from oil and water, making it possible to efficiently separate oil and water. In the present invention, in specific parts of the porous sheet,
It is important that a water-insoluble water-absorbing gel layer is formed. The type or formation means of the water-insoluble water-absorbing gel layer is not particularly limited and can be exemplified in a wide variety of ways. For example, as a means for forming a water-absorbing gel layer, (1) add ammonium persulfate, persulfate, Adding a polymerization catalyst such as soda, potassium persulfate, and hydrogen peroxide, and a condensation catalyst such as ammonium chloride and primary ammonium phosphate, impregnating the porous sheet with such aqueous solution,
A method in which a water-insoluble water-absorbing gel layer is formed by a polycondensation reaction by applying it by coating, spraying, etc., and then heating and drying it at a temperature of about 80 to 110°C. (2) Ionic charge An aqueous solution of a substance with a charge (a compound with a cationic charge such as a pyridine group or a quaternary ammonium group) is added to the porous sheet, and then an aqueous solution of a substance with a charge (a compound with an anion charge such as an aboxyl group or a sulfone group) is added to the porous sheet. A method of impregnating an aqueous solution of a compound) and ionically bonding it on or inside a porous sheet to form a desired ion complex; A method in which a gel compound is formed by a coupling reaction between a polymer compound and a polyvalent metal salt such as magnesium sulfate or calcium chloride, that is, a porous sheet containing an aqueous solution of a polyvalent metal salt in advance, coating, spraying, etc. (4) a method of impregnating a hydrophilic natural or synthetic polymer compound with a hydrophilic natural or synthetic polymer compound; A method of insolubilizing water without losing water absorption, i.e., adding chromium alum, potassium alum, etc. to a porous sheet.
A method in which a crosslinking agent such as formalin, zinc chloride, boric acid, or magnesium chloride is impregnated, and a gel forming agent such as gelatin, polyvinyl alcohol, alginic acid, mannan, or cellulose compound is added to form a gel compound through a chemical crosslinking reaction. , (5) A method using a substance that absorbs water and swells to form a water-insoluble gel, such as impregnating and coating a porous sheet with a cross-linked product of polyethylene oxide (soluble in organic solvents);
Various methods may be used, such as attaching by spraying, or adding collagen fibers, low-substituted carboxymethylated cellulose, polyvinyl fibers, etc. into the porous sheet in advance by mixing paper, blending, etc. In the present invention, the water-insoluble water-absorbing gel layer as described above is formed on the surface of the porous sheet that is to be brought into contact with oil and water and/or on the surface of the liquid passage. It is important that the porosity is not compromised. To form a water-absorbing gel layer, the desired filtering method (natural gravity, pressurization method, etc.) can be selected by selecting a filter material that takes into account the reduction in porosity (materials that can have sufficient porosity and their combinations), etc. It is desirable to design according to the If the water permeation amount is too large, the efficiency of oil-water separation will decrease and the tendency for oil and water to seep will increase, and if the water permeation amount is too small, the oil-water separation rate will be extremely reduced. In the present invention, in addition to forming the water-absorbing gel layer as described above, a treatment is further performed to enhance and sustain the effects of oil-repellent, oil-resistant, oil-separating functions such as oil collection and coarsening of oil droplets. is desirable. For example, oil repellents such as fluorine compounds, chromium-fluorine compounds, lipophilic agents or oil scavengers such as stearic acid compounds, silicone compounds, wax compounds, higher alkyl alcohols, silicone alkylene oxides, fluorine compounds, etc. Surface tension lowering agents such as surfactants or oil collectors may be added to the water-insoluble water-absorbing gel layer, or such effects may be applied, impregnated, sprayed, etc. before or after the formation of the water-absorbing gel layer. processing of porous sheets, etc. Furthermore, the porous sheet can have a lipophilic portion formed together with a water-absorbing gel layer. For example, by mixing polyolefin fibers, pulp, synthetic fibers, glass fibers, etc. by blending, blending, etc. to form a filter material, the separation effect through oil collection, growth, and desorption of oil droplets can be improved. I can do it. In the present invention, the porous sheet has characteristics that can sufficiently withstand use as a filter, that is,
A wide range of materials can be used without particular limitation as long as they have water permeability, water resistance, pressure resistance, durability, etc. For example, cloth, non-woven fabric,
There are paper, foam sheets, etc., pulp, cotton,
Non-woven fabrics such as paper and non-woven fabrics mainly made of cellulose fibers such as rayon and acetylcellulose are used after being imparted with water resistance, pressure resistance, durability, etc. by the reinforcement method described in Patent No. 659628. In addition, since porous sheets made of woven fabrics such as cloth already have properties as filters such as water resistance and pressure resistance, the strengthening method described above may be omitted, but of course the strengthening treatment is applied. You can also. In addition, a method of mixing heat-melting synthetic pulp (polyolefin, nylon, polystyrene, etc.) to form a non-woven perforated sheet and fusing the synthetic pulp by heat treatment, urea-formalin condensate, melamine - Applying crosslinking compounds such as formalin condensates, epichlorohydrin compounds, methylol group-containing compounds, divinyl sulfone compounds to porous sheets, impregnation, spraying, etc. to strengthen the filter without losing its function. It is possible. In addition, porous sheets in the present invention include those made of synthetic fibers such as polyethylene, polypropylene, phenolic resin, polyester, and polyamide, as well as glass fibers,
Of course, materials made of ceramic fibers, inorganic fibers such as asbestos, or composites of the above-mentioned fibers may also be used. Therefore, in the present invention, it is a preferred embodiment to perform a fixing treatment so that the specific water-absorbing gel layer does not come off from the porous sheet. For example, depending on the type of water-absorbing gel layer or porous sheet, a cationic fixing agent such as polyethyleneimine, epichlorohydrin polyamine, dicyandiamide-formalin condensate, or anionic fixing agent such as urea-formalin condensate or melamine-formalin condensate may be used. It can be carried out by coating, impregnating, spraying, etc. on a porous sheet before or after forming the water-absorbing gel layer, or by mixing it into the water-absorbing gel layer. Next, embodiments of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such explanations. Examples 1 to 5 Polyolefin-based synthetic valves (polyethylene,
A two-component porous sheet consisting of Mitsui Zerapack's SWP) and Kotton pulp is formed using a normal wet papermaking method. This sheet is treated in a drum heating machine at 170°C for 2 to 3 minutes to heat-seal the synthetic pulp and strengthen its water resistance, pressure resistance, and durability. Thereafter, a methanol solution of 0.1% by weight polyethyleneimine was applied to the sheet at an impregnation rate of 100% by weight to the sheet to fix the oil/water separation layer. Next, 15 gr of N-methylol acrylamide,
Fluorinated polymer (“Asahi Guard” AG-
530, 15% by weight liquid, manufactured by Asahi Glass Co., Ltd.), 0.5g of ammonium persulfate, and 1.5g of ammonium chloride in 500ml of water, and the solution was applied to the sheet at a content ratio of 100% by weight to the sheet. Thereafter, it was dried at 100°C and heated with a drum at 110°C for 2 minutes to form a water-insoluble water-absorbing gel layer. The properties of the resulting treated sheet are shown in Table 1 below.

[Table] The above characteristics were measured by TAPPI and JIS methods. The following tests were conducted on each of the sheets described above, and the results are shown in Tables 2 and 3 below.
Similar tests are conducted in each of the following Examples. (A) Wet the specimen with water, drop 0.5 ml of spindle oil onto it, and place the specimen on dry paper. At this time, the water in the specimen is transferred to the paper and the oil is absorbed. Measure the time until the oil droplets disappear. The larger this value is, the better the oil-water separation ability is. (B) Place the specimen on paper and add 0.5ml of spindle oil.
and 1 ml of water. After that,
Drop 1 ml of water every 30 minutes. After 4 hours, the paper is taken out, air-dried, and oil marks on the paper surface are checked under ultraviolet light, and the ratio b/a of the radius a of the water penetration circle to the radius b of the oil penetration circle is measured. The smaller this value is, the better the oil-water separation ability is. (C) A holder that descends from the water tank to the receiving tank at an angle of 60 degrees is installed, the specimen is placed on the top of the holder, and the water is constantly moved inside the specimen by a siphon effect. Place one drop on the slope of the specimen. At this time, the oil droplets either spread out in the form of a film or fall down in the form of oil droplets. 30 minutes after the oil drop, the specimen is air-dried, the oil mark is confirmed under ultraviolet light, and the oil mark width is measured 3 cm below the oil drop position. The smaller this value is, the better the oil-water separation ability is. (D) Oil-impregnated water containing 1000 ppm of machine oil dispersed and mixed at 500 to 300 rpm was passed through the specimen filter 2.
An overpressure of 0.2
Pass through at Kg/cm~0.5Kg/ ^cm2 . The over area is 6×11
×2 cm ² . In this case, measure the overpressure, total water flow rate, average overspeed, overwater content, and overloss rate. In addition, the over-reduction rate is determined by measuring the elapsed time for each water flow rate, graphing the overcapacity reduction curve, and then calculating the average over-gradient (elapsed time/
1). Measure at three points: early, middle, and late water flow, and calculate the average value.

【table】

[Table] Comparative Examples 1 to 5 Table 4 below shows filter properties obtained by simply subjecting untreated porous sheets similar to those in Examples 1 to 5 to a drum heat treatment at 170° C. for 2 to 3 minutes.

[Table] The same tests as in Examples 1 to 5 were conducted on these heat-treated sheets, and the results are summarized in Tables 5 and 6 below.

【table】

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[Table] Example 6 A sheet filter that had been subjected to the fixing treatment in the same manner as in Example 5 was further subjected to the following treatment. Namely, 5 gr of N-methylol acrylamide, 20 gr of acrylamide, and methylenebisacrylamide.
0.5gr, dimethylaminopropionitrile 2
ml, fluorine-based compounds (“Asahi Guard, AG-
530 15% by weight liquid, manufactured by Asahi Glass) 50gr, fluorine-based surfactant (Adeka Flow manufactured by Asahi Denka)
FK1006) 2.5mr, same (FK1005) 1gr with water 500
20 parts by weight of the solution added to 100 ml of water, 5 gr of ammonium persulfate, and 5 gr of ammonium chloride to 1 part by weight of the solution added to 100 ml of water are applied to the filter using a contact mixing spray method to form a water-absorbing gel layer. The coating solution is dried at 80-90°C and heat-treated at 100-110°C for 2 minutes to make the water-absorbing gel layer insoluble in water. The coating amount is 100% by weight on sheet. The properties, results of tests A to C, and results of test D of the filter with the thus obtained water-insoluble water-absorbing gel layer are shown in Tables 7 and 8 below, respectively.
The results are summarized in Table 9.

【table】

【table】

[Table] Examples 7 to 9 Phenol-based synthetic fibers (“Kynol” manufactured by Nippon Kynor Co., Ltd.), asbestos fibers, and polyolefin-based synthetic pulp (SWP) were adjusted to a blending ratio of 7:2:1 (weight ratio), and the total 6% by weight of polyvinyl alcohol-based swellable pulp ("Fibribond" manufactured by Kuraray) is added to the fiber content, and a porous sheet is formed by a normal wet papermaking method (used in Example 7). Acrylic synthetic fiber (“Bonnell” manufactured by Mitsubishi Rayon), asbestos fiber, and SWP are adjusted to a blending ratio of 5:2:3, and “Fibribond” 6 is added to the total fiber content.
% by weight and form a porous sheet using conventional wet papermaking methods (used in Example 8). “Kynol”, ceramic fiber, SWP 4:
The blending ratio was adjusted to 4:2, "Fibribond" was added in an amount equivalent to 6% by weight based on the total fiber content, and a porous sheet was formed by a normal wet papermaking method (used in Example 9). Each of the sheets described above is treated in a drum heating machine at 170°C for 2 to 3 minutes, and the composite valve is heat-sealed to enhance water resistance, pressure resistance, and durability. After that,
A methanol solution of 0.05% by weight polyethyleneimine was applied to the sheet at a content ratio of 100% by weight to the sheet, and an oil/water separation layer was fixed. Next, as the first liquid, 25 gr of N-methylolacrylamide, 10 gr of acrylamide, 0.5 gr of methylene bisacrylamide, and 2 ml of dimethylaminopropionitrile were dissolved in 500 ml of water, and as the second liquid, 5 gr of ammonium persulfate and 5 gr of ammonium chloride were added. Prepare a solution dissolved in 100ml of water. The two liquids are mixed at a ratio of 1st liquid/2nd liquid = 20/1 (volume ratio) using a contact mixing spray method.
The fixing-treated sheet was coated with an impregnation rate of 100% by weight, dried at 80-90°C, and further heated at 100-110°C for 2 minutes to form a water-insoluble water-absorbing gel layer. Furthermore, cationic polymer compounds (AG-Fix,
A solution of 5g (manufactured by Meisei Chemical) dissolved in 200ml of water and made up to 500ml with methanol was spray-coated onto the gel layer-containing sheet at an impregnation rate of 50% by weight, dried at 100°C, and dried at 100°C. Final treatment was applied. Thereafter, a second water-insoluble water-absorbing gel layer was formed in the same manner as in Example 6. The characteristics of the filter thus obtained, the results of Tests A to C, and the results of Test D are summarized in Tables 10, 11, and 12 below, respectively.

【table】

【table】

[Table] Example 10 Commercially available paper (No. 26 manufactured by Toyo Paper Co., Ltd.) was used. 25g of N-methylolacrylamide, 2.5g of ammonium persulfate, 2.5g of ammonium chloride and 500g of water
ml of the solution was applied to the paper at an impregnation rate of 100% by weight, dried at 80-90℃,
Heat treatment at ℃ strengthens paper's water resistance and pressure resistance. Next, a cationic polymer compound (manufactured by Meisei Chemical Co., Ltd.)
A solution prepared by dissolving 5g of AG-Fix) in 200ml of water and bringing the total volume to 500ml with methanol is spray applied to the reinforced paper so that the impregnation rate is 100% by weight. Next, as a first liquid, 5 gr of N-methylolacrylamide, 20 gr of acrylamide, 0.5 gr of methylenebisacrylamide, 2 ml of dimethylaminopropionitrile, and a fluorine-based oil repellent (15% by weight liquid of "Asahi Guard" AG530, manufactured by Asahi Glass) 50g
r, fluorine-based oil collecting agent (“ADEKA FLOW” FK1006 manufactured by Asahi Denka) 2gr, and “ADEKA FLOW”
1g of FK1005 dissolved in 500ml of water, 2nd
Prepare a solution in which 5 gr of ammonium persulfate and 5 gr of ammonium chloride are dissolved in 500 ml of water. The two liquids were applied to the treated paper using a contact mixing spray method at a ratio of 1st liquid/2nd liquid = 20/1 (volume ratio), dried at 80 to 90°C after coating,
~110℃×2 minutes. The characteristics and test results of the filter thus obtained are shown in Tables 13, 14, and 14 below, respectively.
They are summarized in Table 15.

【table】

【table】

【table】

[Table] As explained in detail above, according to the present invention, the water-absorbing gel has a water-permeable and water-absorbing function that selectively improves the permeability of water from oily water, and a porous sheet that has oil viewing properties to collect oil. When the oil droplets grow and become coarse particles, they are repelled by the water stored inside the water-absorbing gel body and quickly released from the porous sheet. It is possible to provide an oil/water separation filter with extremely low filtration efficiency and excellent filtration efficiency.

Claims (1)

[Scope of Claims] 1. An oil/water separation functional layer mainly composed of a water-insoluble water-absorbing gel layer and having a water-permeable water-absorbing function and an oil-repellent function due to occluded water, the surface portion of the porous sheet that is to be brought into contact with oil/water, and/or Or an oil/water separation filter, characterized in that it is formed on the surface of the liquid passage. 2. The oil-water separation filter according to claim 1, wherein the porous sheet has characteristics that can withstand the filter, such as water resistance, pressure resistance, and durability.