JPS61257211A - Process for separating fine oil drop by coarsening particle size thereof - Google Patents

Abstract

PURPOSE:To separate fine oil drops by coarsening the particle size by using a fibrous sheet contg. >=50% fiber having 0.1mum dia. of single fiber and having each specified packing rate, thickness of the sheet and surface tension of the fiber surface. CONSTITUTION:A filter element comprises fiber contg. >=50% single fiber having 0.1-10mum dia. Suitable packing rate of the fiber is 10-70wt%. Suitable thickness of the element is >=0.1mm and <=70mm. Suitable critical surface tension of the fiber surface is 20-40dyne/cm. The element comprising a fibrous sheet having the above-described constitution is used in an optional shape, such as flat film, cylindrical, or spiral, etc. Further, the fibrous sheet may be used as a single sheet or plurally layered shape. The liquid to be treated is allowed to permeate for the coarsening treatment by feeding the liquid at a fixed flow rate to the sheet, or by permeating the liquid under a fixed pressure, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for reliably and quickly coarsening and separating minute oil droplets dispersed in a liquid that undergoes phase separation from oil.

L Conventional technology] Technology for separating minute oil droplets dispersed in a liquid that phase separates from oil is in high demand in fields such as pollution prevention, marine pollution prevention, and other uses for liquids that phase separate from oil or oil. . For example, separation of minute oil droplets dispersed in waste water in facilities that use oil such as machinery industry, petrochemical industry, food industry, etc., separation of minute oil droplets dispersed in water accumulated on the bottom of a ship, L2s
2-)! An example of this is the separation of minute oil droplets dispersed in an expensive heating medium such as J-fluoroethanol.

A wide variety of techniques are known to separate these minute oil droplets, including gravity separation, centrifugal separation, oil collection separation, membrane separation, chemical coagulation basin separation, and magnetic separation. One of these methods is the method of separating droplets into coarse particles.

By passing the processing liquid through an element (made of fiber, stainless steel, etc.) that has a coarsening function, the oil droplets in the processing liquid are destroyed, coagulated, and coalesced within the element, and can be easily separated based on the difference in specific gravity. The idea is to make oil droplets of the same size.

This method is a very advantageous separation method industrially because dispersed oil droplets can be separated in a shorter time and with less energy and equipment than other separation methods.

Conventionally, a well-known method for coarsening and separating is a method of coarsening and separating using a fiber aggregate coalescer made of nylon, rayon, glass fiber stainless steel fiber, etc. These are relatively large oil droplets (
5μm or more), but for small and stable oil droplets of about 0.1 to 5μm or high oil concentration, it reliably converts the fine oil droplets into coarse particles. It had the disadvantage that it was impossible to convert. Also, 5Ik
It is difficult to reliably coarsen oil droplets larger than n with a single-stage coalescer, and there is also the drawback that a multi-stage coalescer must be used.

As an improvement on the above-mentioned drawbacks,
As seen in No. 42, an element has been proposed that coarsens minute oil droplets by reducing the porosity of a fiber aggregate that has an affinity for minute oil droplets.

However, it is difficult to reliably separate extremely small and stable oil droplets of about 0.1 to 1 μm into coarse particles, and the problem is that the throughput per unit area is small due to the small porosity. was.

[Problem that the invention seeks to solve]

An object of the present invention is to overcome the drawbacks of the prior art as described above, and to provide a method for separating ultrafine oil droplets from a liquid by coarsening ultrafine oil droplets dispersed in a liquid that undergoes phase separation from oil. Our goal is to provide the following.

[Means to Solve the Problem] The present inventors have solved a problem that was previously difficult to solve by passing a processing liquid containing minute oil droplets through a fibrous meat made of ultrafine fibers that have an affinity for minute oil droplets. The present invention was achieved by discovering the fact that fine oil droplets of 0.1 to 5 μm can be coarsened reliably and quickly.

The reason why ultrafine fibers have made it possible to coarsen and separate ultrafine oil droplets of 0.1 to 5 μm, which was difficult to coarsen and separate in the past, is because ultrafine fibers have a small amount of fiber per unit weight. Since the surface area is extremely large, there are many opportunities for minute oil droplets to adhere and be destroyed.When making a fibrous sheet, the size of each pore is small because ultrafine fibers are used, so there are many opportunities for minute oil droplets to adhere and be destroyed. It is presumed that this is because it is possible to capture even

The method for coarsening and separating minute oil droplets of the present invention uses fibers with a diameter of 0.1 to 10 μm as main fibers, and a fiber filling rate of 10 to
70 yen, thickness 0.1~7°0■ and critical surface tension 2
It is characterized by using a fibrous sheet of 0 to 40 dyne/cIR.

The "oil" used in the present invention refers to machine oil and gear oil.

In addition to so-called oils such as cylinder oil, turbine oil, animal and vegetable oils, kerosene, diesel fuel oil, fluorine oil, and silicone oil, liquid petroleum ethers, N-hexane,
Aliphatic hydrocarbons such as N-hegetane, ofl-like hydrocarbons such as cyclohexane and cyclohegetane,
Aromatic hydrocarbons such as toluene and xylene, tetrachlorethylene, trichlorethylene, chloroform,
Refers to halogenated hydrocarbons such as fluorinated solvents.

In addition, "liquids that phase separate from oil" are most typically water, but also include water containing metal salts such as NaCL, LICt, CaCA2, methanol, ethanol, 2
．． These include alcohols such as 2.2-trifluoroethanol, organic solvents such as butanediol, dimethylacetamide, dimethylformamide, and acetonitrile, and water containing these liquids. The treatment liquid to which the present invention is applied refers to a system in which the oil is present in the form of minute oil droplets in a liquid that undergoes phase separation from these oils, and may contain a surfactant or the like.

The term "coarse graining" used in the present invention refers to a phenomenon in which fine oil droplets, which usually have a diameter of 0.1 to 50 μm, become coarse oil droplets with a diameter of 0.1 μm or more. Coarse oil droplets of 0.5 m or more are easily floated and separated due to the difference in specific gravity between the oil and the phase-separated liquid.

The coarse particle separation method in the present invention means that the treatment liquid is passed through a fibrous sheet made of ultra-fine fibers to coarsen the minute oil droplets in the multi-treatment liquid within the fibrous sheet and then separated by specific gravity. The method is money. "Fibrous sheet" used in the method of the present invention
The material may be a woven fabric, a non-woven fabric, a mat, a sheet, or a felt. The fibers constituting the fiber sheet are not limited in any way, but include, for example, polyethylene terephthalate, polyethylene terephthalate adipate, polyethylene terephthalate inphthalate,
Fibers of polyester copolymers such as polyethylene terephthalate/sebacate, polyethylene terephthalate/dodecanedioate, and polybutylene terephthalate;
Polyhexamethylene azitzamide, polyhexamethylene sepacamide, polyhexamethylene decamide, polyhexamethylene hexamide, polycabramide, polyoctamide, polynonamide, polydecamide, polydodecamide,
Polyamide fibers such as polytetramid, polyamide
Imide fibers, aromatic polyamide fibers, fibers of polyether esters such as polyoxypenzoate, fibers of halodane-containing M polymers such as polyvinyl chloride, polyvinylidene chloride, polyvinylidene polyfluoride, polytetrafluoroethylene, etc. Examples thereof include polyolefin fibers such as glopylene polyethylene, peristaltic acrylic fibers and polyvinyl alcohol fibers, regenerated cellulose fibers, acetate, and natural fibers such as cotton, hemp, silk, and wool.

These fibers can be used alone or in combination.

The single fiber diameter of the fibers constituting the above fibrous sheet is O01
~10 ttm is mainly used. When the single fiber diameter exceeds 10 μm, extremely fine (0.1 to 1 μm) oil droplets cannot be captured and destroyed within the fibrous sheet.

Therefore, sufficient grain coarsening performance cannot be obtained.

Fibers smaller than 0.1 μm are difficult to produce uniformly industrially. Preferably, the living body has a single fiber diameter of 0.3 to 7 μm. "Mainly" means that the weight of fibers having the above-mentioned single fiber diameter is 50% or more of the total weight of the fibers constituting the fibrous sheet, preferably 7% or more.
It means that it is more than 0 yen. For example, if the fibers are uniform in the length direction with a diameter of 7, even in a fibrous sheet obtained by mixing fibers with various diameters, 0.1 of the single fibers in the fibrous sheet It is sufficient if the weight of fibers having a diameter of ~10 μm is 50% or more. If the weight of the single fibers having a diameter of 0.1 to 10 μm is less than 50% of the total weight of the fibers constituting the fibrous sheet, sufficient coarse graining performance cannot be obtained.

The fiber filling rate of the fibrous sheet is in the range of 10 to 7 (l). The "n1 fiber filling rate" is defined by the following formula. When the fiber filling rate is less than 10 l, extremely fine oil droplets are formed. Since it permeates without being captured by the fibrous sheet, the coarsening performance is low, and the fiber filling rate increases due to the sagging of the fibrous sheet, and the liquid permeability changes greatly from the beginning to the ib, which is undesirable. Moreover, if it exceeds 70%, industrially usable liquid permeability cannot be obtained.The desirable range of the fiber filling rate is 20 to 60 Ilj.

The thickness of the fibrous sheet is 0.1 m or more and 70 m or less, preferably 0.2 m or more and 50 m or less. If the thickness is less than 0.1 square centimeters, a large proportion of extremely small oil droplets will pass through without being captured by the fibrous sheet, and sufficient grain coarsening performance will not be obtained. If it exceeds '70, the pressure loss during liquid permeation becomes too large.

The fibers constituting the fibrous sheet have a critical surface tension in the range of 20 to 40 dyne/cIn. The surface tension of oil as used in the present invention varies slightly depending on its chemical composition, but is in the range of 20 to 35 dyne/cm. The critical surface tension of the fiber is 20 dyne/α
If it is less than that, the oil droplets will not wet the fiber surface, the oil droplets will not be destroyed, and the oil droplets will not become coarse enough. Also,
A liquid that phase separates from oil when it exceeds 40 dyne/cIn (
Since the fiber surface becomes easily wetted by water (mainly water), oil is not destroyed on the fiber surface, which is undesirable. The critical surface tension of the fiber surface is preferably in the range of 20 to 35 dyne/sub.

The "critical surface tension" here is measured by the following method. A nonporous film made of the same material as the fibers forming the fibrous sheet is used as a sample for production measurement. In the case of fibers whose surfaces are coated or chemically bonded with various processing agents, first a non-porous film is made of the same material as the fibers, and the same processing agents are coated or chemically bonded to the fiber surfaces. The sample is processed under certain conditions and used as a sample for measurement. The critical surface tension is the surface tension when the contact angle θ=O, so the surface tension of each contact angle t of the sample mentioned above was also measured with a liquid, and by extrapolation, the surface tension was calculated as θ=0.
If the surface tension at zero is determined, the critical surface tension can be obtained.

In order to make the fiber surface have a critical surface tension of 20 to 40 dyne/cm, the fibers constituting the fibrous sheet must have a critical surface tension of 20 to 40 dyne/cIn.
The critical surface tension of the fiber is 2.
Set it to 0 to 40 dyn/3.

A specific example of a fiber having a critical surface tension of 20 to 40 dyne/an 1 is polyethylene (density 0.
95.31 dyne/cfR), polypropylene (2
9,0 dyne/cm, polystyrene (33, Ody
ne/cm) Polyfluorinated vinyl IJ Den (25, Od
Typical examples include yn·/3).

Specific methods for modifying the material so that the critical surface tension is 20 to 40 dyn/3 include silicon compounds such as dimethylpolysiloxane, fluorine compounds with perfluoroalkyl groups, and 2-ethylhexyl zirconium. Examples include a method of modifying the fiber surface using a zirconium-containing compound such as ester, a methylol compound such as stearin methylolamide, an acid chloride compound such as stearic acid chloride, or a hydrocarbon metal such as polyethylene or polypropylene. The compound for modifying the fiber surface is not limited to the above-mentioned compounds, and in the method of the present invention, any compound can be used as long as it can modify the fiber surface so that the critical surface tension becomes 20 to 40 dyn/cM. .

In the coarse particle separation method of the present invention, the liquid permeation method during the coarse particle process is not limited in any way, such as a method of sending the liquid at a constant flow rate to the fibrous sheet, or a method of feeding the liquid to the fibrous sheet under a constant pressure. There are methods such as passing through a shaped sheet.

The fibrous sheet can be used in any desired form, such as a flat membrane, a cylinder, or a circular shape, but from the viewpoint of processing efficiency, it is preferable to use the fibrous sheet in a bellows-like form. Further, the fibrous sheet can be used as a single sheet or as a stack of a plurality of sheets.

Wire mesh for the purpose of reinforcement etc. for fibrous sheets.

It is also possible to use reinforcing materials such as fibrous structures.

Furthermore, in order to collect dust in the processing liquid, it is also possible to place a dust-collecting material as a pre-filter before processing the liquid to be processed with the fibrous sheet.

For example, examples of the blur filter include a film-like or cotton-like dust collection material.

The present invention can also be incorporated into a process for concentrating and recovering components from a multicomponent system by distillation. In other words, if the dispersed system (distilled fraction or residual fraction) obtained from the distillation apparatus is subsequently coarsened by the method of the present invention and then subjected to specific gravity separation, more effective and highly accurate concentrated recovery becomes possible. preferable.

On the other hand, it is also possible to carry out the final separation of the permeate that has been coarsened and separated by the method of the present invention using a membrane or sheet that selectively allows only oil to permeate through specific gravity separation. In addition, when recovering a solvent using the activated carbon adsorption method, in order to recover a good solvent by adsorbing it to the activated carbon, steam is blown directly to remove the solvent adsorbed to the activated carbon. It is also possible to separate and collect the particles after coarsening them using a sheet.

[Effects of the Invention] According to the method of the present invention, coarse grain separation has conventionally been difficult.
, it is possible to reliably and quickly coarsen and separate even ultrafine oil droplets of 1 to 5 μm in size, and what was previously required to be coarsened in multiple stages can be separated in one step. can be made smaller.

〔Example〕

Next, in the following examples to explain the present invention, the critical surface tension of the fiber surface constituting the fibrous sheet was measured using a Kyowa Kagaku grade CA-D type contact angle measuring device. . In addition, the oil concentration was measured using an oil content analyzer manufactured by Horiba. The size of the minute oil droplets was measured using optical micrographs.

“Example 1 Six types of fibrous sheets made of polypropylene fibers with a single fiber diameter of 0.5 to 15.4 μm were molded (fiber filling rate 2
1%, thickness 1.5 wg). That is, single fiber diameter 0
．． Two types of fibrous sheets of 5 and 1.5 μm were obtained by melt blowing. Moreover, the single fiber diameter is 3.7 to 15.
A sheet of 4 types of fibers of 4 types was obtained by cutting the fibers obtained by direct spinning into 5-length pieces, and then using a wet paper-making method. The six types of fibrous sheets with different single fiber diameters obtained in this way were mounted on a Millipore membrane filter holder, and 2.0 kg of the treatment solution prepared under the following conditions was applied.
The liquid was fed at a pressure of /- to perform coarse graining treatment.

The critical surface tension of the surface of the polypropylene fibers constituting the fibrous sheet was measured and found to be 29.3 dyne/tension.

Liquid to be treated: Add 100cc of heavy oil B to 100ml of water,
The mixture was stirred with a mixer for about 10 minutes to prepare an oil-water mixture in which oil droplets of heavy oil B were dispersed in water. The oil concentration in the area where the oil droplets were dispersed was 280 ppm, and the size of the oil droplets was 0.5 μm to 1.5 μm.

The results are shown in Table 1.

As is clear from the results in Table 1, the method of the present invention has extremely good grain coarsening separation performance, and is clearly visible.

When the permeated liquid after treatment was taken into a graduated cylinder and visually observed, it was found that oil droplets coarsened to 0.5 wm to 2 cm in size rose in the water phase in the case of the method of the present invention, and immediately became clear water. It was separated into a liquid phase and an oil liquid phase. On the other hand, the permeate liquid of the comparative example was cloudy because very fine oil droplets were still dispersed in the aqueous phase.

Example 2 A fibrous sheet 2M1 made of polyethylene terephthalate fibers having single fiber diameters of 1.7 μm and 3.8 μm, respectively, was prepared by melt blowing (thickness: 2.5 μm, fiber filling rate: 28%).

On the other hand, single fiber diameter 12.1 obtained by direct spinning method
After cutting each of the 15.1 μm fibers into lengths of 5 m, two types of fibrous sheets (nonwoven fabrics) were created by a wet papermaking method (thickness: 2.4 m, Fiber Optic tR 25 tlI).

The fiber surfaces of a total of four fibrous sheets were modified under the conditions shown below. The critical surface tension of the modified polyethylene terephthalate fiber surface was measured and was 30.5 d.
It was yne/cIn.

Modification conditions: Po1on MR 4% by weight and catalyst 0
After immersing the above fibrous sheet in a mixed solution of 24% by weight (manufactured by Shin-Etsu Silicon Co., Ltd.), the liquid was removed and dried at 100°C for 3 minutes.
Heat treatment was performed at 70°C for 1 minute.

The thickness and fiber filling rate of the modified fiber sheet are respectively the second
Shown in the table.

Table 2 Single fiber diameter (μm) Thickness (■)! Male! the law of nature! Eli 1
．． 7 2.8 303.8
2.8 3012.1
2.5 2715.1
2.5.27 Using the four types of fibrous sheets thus obtained, an oil droplet coarsening separation experiment was conducted in the same manner and under the same conditions as in Example 1. The treatment liquid was prepared by adding the same liquid 1001 obtained in Example 1 and shortening the stirring time in the mixer to 10 seconds.
Seeds were used. After stirring for 10 seconds, the oil concentration was 210 p, p, m, and the size of the oil droplets was 2 to 5 μm. The results are shown in Table 3.

As is clear from the results in Table 3, it can be seen that according to the method of the present invention, even extremely fine oil droplets of 0.5 to 1.5 μm can be reliably separated into coarse particles. Note that the condition of the treatment liquid was the same as in Example 1.

The following all white Example 3 Single fiber diameter 3.0μm, thickness 0 by melt blowing method
．． 2. A polypropylene nonwoven fabric with a fiber filling rate of 5 was obtained. Next, this nonwoven fabric was pressed to create six types of nonwoven fabrics with a fiber filling rate of 5 to 80 inches. That is, the pressing process is 1 to 1
50 J/1ys2, and in addition, nonwoven fabrics with different fiber filling rates were created depending on the pressing temperature and time. Next, a fibrous sheet with a thickness of 10.0±0.1+w+ was created by overlapping several sheets of nonwoven fabric with the same fiber filling rate (the critical surface tension of the fiber surface was 29.3
dyne/cm). The fibrous sheet thus obtained was subjected to grain coarsening treatment using the same equipment and conditions as in Example 1 by passing the following treatment liquid. Processing liquid permeation rate (
processing speed) with a rotameter (maximum measurement value 2000#!j
/m1n) to measure it. The results are shown in Table 4.

Treatment liquid: Add 50 cc of Mechanical Oil Nippon Oil Suit Arm No. 22 (Nippon Oil & Fat Layer NS 206) to 100ml of water, stir with a mixer for about 30 minutes, and add suit f-
An oil-water mixture in which Hyland 22 oil droplets are dispersed.

The oil concentration of the phase in which oil droplets are dispersed is 350 p, p-m.
The size of the oil droplets was 05 to 2.0 μm.

The rest below! As is clear from the results in Table 4, it can be seen that sufficient coarse grain separation cannot be achieved with a fibrous sheet having a fiber filling rate of less than 100%. 3001 for fibrous sheets of 70 inches or less
While the permeation rate is d/min or more, the permeation rate of an 80% fibrous sheet is extremely slow and has low industrial utility value.

Example 4 Nylon 66# with single twill fibers of 5.0 μm obtained by direct spinning method! After cutting the fiber into a length of 5 m, a nonwoven fabric with a thickness of 0.05 mm and a fiber filling rate of 13% was created by a wet papermaking method. In order to modify the surface of the nylon 6'6 fibers, the nonwoven fabric was treated in the same manner and under the same conditions as in Example 2 to produce a fibrous sheet 1. The critical surface tension of the fiber surface was measured and found to be 30.5 dyne/cm.

This fibrous sheet 1 was tightly wound into a spiral shape to create a fibrous structure with a diameter of 45wx and a height of 10100O+. The fiber filling rate of this product was 10 inches. Next, the thickness of this fiber structure was 50.0 m and 70.0 m, respectively.
, three types of fibrous sheets 2 were made by slicing them into loom shapes.

On the other hand, using the 0.05s+s+ fibrous sheet 1 after surface modification, the thickness was 0.05m and 1.5-1, respectively.
Three types of fibrous sheets 3 were prepared by stacking the fibrous sheets 1 so as to have a thickness of 10 cm.

The three types of fibrous sheet 2 were placed in a stainless steel container with a diameter of 45 mm and an inlet and an outlet, and the liquid was fed from the upper part of the cylindrical fibrous sheet, and the treated liquid after coarsening was sent from the lower part. I tried to get it.

Three types of fibrous sheets 3 were mounted on the same Millipore membrane filter holder as in Example 1, and subjected to coarse graining treatment. All liquids were fed at a pressure of 2.0 at 9/an''. The treatment liquid was prepared in the following manner.

Treatment liquid: 2.2.2-) 50 cc of turbine oil P-32 manufactured by Idemitsu Kosan Co., Ltd. was added to 50% refluoroethanol and stirred for 20 minutes with a mixer to prepare an oil-water mixture. The oil concentration of the phase in which oil droplets are dispersed is 410 p, p
, m, and the size of the oil droplets was 0.5 to 2.0 μm. (
The oil concentration in this case was measured using a Ganu chromatograph manufactured by Shimadzu Corporation. ) The results are shown in Table 5.

As is clear from the above results, it can be seen that both the oil concentration and the permeation rate of the permeated liquid are good in the examples of the present invention.

Example 5 Single fiber diameter 1.7 μm, thickness 2 by melt blowing method
．． 5. A fibrous sheet 4 (nonwoven fabric) of I-ethylene terephthalate with a fiber filling rate of 28 was prepared.

These nonwoven fabrics are treated under the following methods and conditions to produce fibrous sheets with different critical surface tensions on the fiber surfaces 5.6.
．． 7 was created.

Fibrous sheet 5: Same treatment as Example 2 Fibrous sheet: Finetex 8 manufactured by Dainippon Ink Co., Ltd.
After immersing in a 4% solution of P, the liquid was removed, and a 100″CX3
After drying for 1 minute, heat treatment was performed at 150°C for 1 minute.

Fibrous sheet 7: Asahi Guard 800-4 manufactured by Meisei Chemical Co., Ltd.
After being immersed in a wt% solution, the liquid was removed, dried at 100C for 3 minutes, and then heat treated at 180°C for 1 minute.

Fibrous sea) 4.5, 6.7 in the same manner as in Example 2,
Experiments were conducted under these conditions to evaluate the coarsening performance. Table 6 shows the properties of the fibrous sheet after surface modification.

Table 6 Fibrous sheet 42.528 45#52.82
6 31 #62.826 35 #7 2.8 26 16 The results are shown in Table 7.

As is clear from the above results, even the smallest oil droplets can be reliably coarsened and separated in the examples according to the method of the present invention.

Methods outside the scope of the present invention can separate relatively large oil droplets, but cannot reliably separate extremely small oil droplets.

Claims (1)

[Claims] 1. When separating minute oil droplets dispersed in a liquid that undergoes phase separation from oil, the main fibers are single fibers with a diameter of 0.1 to 10 μm, fiber filling rate of 10 to 70%, and thickness of 0.1 to 70 mm.
The critical surface tension of the fiber surface is 20 to 40 dyne/
A method for coarsening and separating minute oil droplets, which is characterized by using a fibrous sheet with a diameter of 1 cm.