JPS6159766B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a semipermeable membrane suitable for reverse osmosis and ultrafiltration, and a method for using the same, and more specifically, a method for producing a polyamine semipermeable membrane crosslinked with polycycloaliphatic dicarbonyl halide and its use in reverse osmosis. ，
It is related to the usage for ultraviolet rays. Reverse osmosis and ultrafiltration methods have been rapidly developed in recent years as a means of solving the serious problem of absolute and local shortages of water resources worldwide. These methods have the advantage that, in principle, the energy cost is low compared to other substance separation means such as distillation. For this reason, although there has been interest for a long time, no industrial application examples have been found due to the inefficiency of the methods using these semipermeable membranes. Improvements were made. Since the invention of a membrane with an asymmetric or anisotropic structure by S. Loeb and S. Sourirajan (US Patent No. 3,133,132), membrane improvements have progressed dramatically and the industrial application of the semipermeable membrane method has begun. Ta. Based on the knowledge that salt removal by this asymmetric membrane takes place in a dense layer on the surface of the membrane, a method was developed to create an ultra-thin membrane separately from the porous support, and it attracted attention as an ultra-thin membrane method. In this way, both porous supports and ultrathin membranes can be tailored to have the most favorable properties of each. This ultra-thin film method involves casting onto a porous support.
A composite membrane was completed in which a thin film was formed directly using the method, and the surface of the thin film was crosslinked or otherwise modified. The remarkable improvement achieved by this composite membrane was published in Japanese Patent Application Laid-Open No. 1986-
It is disclosed in No. 133282 and Japanese Unexamined Patent Publication No. 1983-40486. These are made by directly casting a flexible polymer such as polyethyleneimine or amine-modified polyepihalohydrin on a porous support and having a dense functional group distribution for crosslinking to form a thin film. This is a method of forming a preferable active layer or ultra-thin film layer on the surface of a thin film by crosslinking it by reaction with a polyfunctional crosslinking agent that can react with the amino group or imino group that is the functional group. This composite membrane consisting of an ultra-thin polyamine layer has excellent permeation flux and excellent exclusion properties against inorganic salts and polar organic molecules. Particularly effective for removing substances that are difficult to remove with conventional cellulose acetate membranes, such as alcohols such as phenol, benzyl alcohol, and ethanol, organic acids such as benzoic acid and acetic acid, and polar organic molecules such as amines such as aniline and pyridine. Its effectiveness has attracted attention. 〓〓〓〓
Unfortunately, however, this indiscriminate rejection of inorganic salts and polar organic molecules has certain disadvantages for industrial applications of membrane separations. As is well known, examples of industrial applications of membrane separation are the desalination of seawater or saline water, the purification of contaminated water for the production of drinking water or industrial water and the identification from industrial or municipal wastewater. Concentration, removal or recovery of substances. In particular, the concentration, removal, or recovery of valuable or harmful substances, together with countermeasures against water resource shortages, can kill two birds with one stone. However, industrial wastewater and other general wastewater contain a mixture of organic molecules and inorganic salts, and in many cases have a high content of inorganic salts. This is one of the reasons why the ion exchange resin method, which is a technology contrasted with the membrane separation method, is difficult to use for industrial wastewater or general wastewater. Even in membrane separation methods, if the content of inorganic salts is high, it becomes difficult to apply reverse osmosis due to the high osmotic pressure on the residual liquid side. Furthermore, the concentrated solution that has been recovered is a mixture of organic molecules and inorganic salts, and has little value as it is. Therefore, it is extremely important to selectively permeate or exclude a specific substance from an aqueous solution in which various different substances, such as organic molecules and inorganic salts, are dissolved. In this sense, as a membrane exhibiting selective permselectivity, a semipermeable membrane of sulfonated polybenz-1,3-oxazine-2,4-dione is disclosed in Japanese Patent Application Laid-Open No. 1982-
No. 24988, and almost all other selectively permeable semipermeable membranes only disclose that water selectively permeates. The present inventor discovered the fact that the removal and recovery of polar organic molecules, which was considered impossible in the past, has become possible with a composite membrane having an ultra-thin layer of polyamine, and the fact that this composite membrane can remove and recover polar organic molecules and inorganic salts indiscriminately. We conducted intensive research considering both the disadvantages of exclusion.
As a result, the disadvantages of the polyamine composite membranes crosslinked with aromatic, cycloaliphatic, heterocyclic, or aliphatic diisocyanates of the disclosed examples are that polar organic molecules can be removed from an aqueous solution of a mixture of polar organic molecules and inorganic salts. The disadvantage of not being able to selectively eliminate the water can be overcome by using a polyamine composite membrane formed by using a polycycloaliphatic diisocyanate as a crosslinking agent, and it also has high water permeability. I found out that it was possible and filed an application first. As a result of further studies, it was found that the polyamine composite membrane using polyalicyclic dicarbonyl halide as a crosslinking agent in the present invention also has high permeation flux and excellent selective exclusion properties. In addition, this semi-permeable membrane can be used to pre-treat wastewater (e.g. coagulation sedimentation, sand filtration, activated carbon filtration, etc.)
If wastewater containing suspended solids is treated with insufficient water retention, the suspended solids will adhere to the membrane surface and the water permeation flux will decrease over time. However, it has also been found that when hot water washing is performed to remove the attached solid content, the solid content is removed very easily and the permeation flux may be restored to its original value. However, when this hot water washing is repeated, the permeation flux and excellent rejection rate of the polyamine membrane crosslinked with the polycycloaliphatic diisocyanate decrease over time and do not recover. Conventional methods for cleaning membrane surfaces include water washing, pickling, alkaline washing, chemical washing, and mechanical washing, but hot water washing has the advantage of being extremely easy to perform by utilizing waste heat such as waste steam. It exhibits an extremely excellent cleaning effect when containing suspended fine rubber particles such as natural rubber or wastewater from a synthetic rubber factory. Therefore, the purpose of the present invention is to provide a new semipermeable membrane using polycyclodicarbonyl halide as a crosslinking agent when forming an ultra-thin polyamine composite membrane, and to provide a new semipermeable membrane that uses a polycyclodicarbonyl halide as a crosslinking agent to form an ultrathin polyamine composite membrane. The object of the present invention is to provide a method for selectively removing or recovering polar organic molecules from among molecules and inorganic salts, and polar organic molecules from among inorganic salts. Another object of the present invention is to provide a semipermeable membrane whose permeation flux can be easily recovered by washing with hot water, and which maintains favorable selective exclusion and high permeation flux even after repeated washing with hot water. The polyamine used in the present invention has (1) a flexible chain as its main chain in order to exhibit a preferable exclusion rate. (2) high reactivity with the crosslinking agent used in the present invention; (3) amino groups as reaction sites or dense distribution of amino groups; and Preferably it is soluble in aqueous media. In addition, from the viewpoint of interaction with the crosslinking agent described later, it is also important to balance the hydrophobicity due to carbon atoms and the hydrophilicity due to nitrogen atoms and oxygen atoms. A polyamine that satisfies these conditions is used.
Examples include polyethyleneimine and polyether polyamine. Polyethyleneimine produced by cationic ring-opening polymerization of ethyleneimine has low crystallinity due to its branching and is preferable for the first condition, and polyethyleneimine is easily available in a wide range of molecular weights from 600 to 100,000. Particularly preferred are those having a molecular weight of 6000 or more. Polyether amine is polyhalomethyl ether represented by the general formula () (X is Cl or Br, n is an integer), or () (R is H, C _1-4 alkyl group, or

For polyhalomethyl ether, which is a reaction product of [formula] group) and a polyhydric alcohol (e.g., ethylene glycol, glycerin, sorbitol, pentaerythritol, etc.) or polyalkylene glycol (e.g., polyethylene glycol, polypropylene glycol, etc.), It is a water-soluble polyetheramine obtained by reacting 2 or more molar equivalents of aliphatic polyamine having at least two primary or secondary amino groups and a molecular weight of 200 or less per mole of halomethyl.
47-397, JP-A No. 48-61597, etc. From the viewpoint of film strength, n is preferably about 50. From the viewpoint of the reaction point distribution, which is the third condition mentioned above, formula () is preferable. The polyalicyclic dicarbonyl halide used as a crosslinking agent in the present invention has the general formula [In the formula, R may be the same or different,
A or B; either one of A' or B' is a halocarbonyl group -
COX (X is a halogen atom such as Cl or Br), the other is hydrogen, α and β are each 0 or 1, n
is 0, 1, 2 or 3, but when n=0, β
represents 1 or 2]. Such compounds are disclosed in, for example, Japanese Patent Application Laid-Open No. 50-129544.
A method in which HCN is added to the unsaturated polyalicyclic cyano compound shown in the above No. by a conventional method, followed by hydrolysis under an acidic catalyst, and further acid chloride.
There are many methods, such as the method shown in JP-A-50-6111, in which the endocyclic unsaturated group of a polyalicyclic unsaturated compound is hydroformylated by an oxo reaction, and then photooxidized with Cl ₂ to obtain a dicarboxylic acid chloride. ,
“SURVEY OF” by CABuehler and DEPeareon
ORGANIC SYNTHESES” (Wiley)
(Interscience, 1970), pages 859 onwards. Specifically, the polyalicyclic dicarbonyl halide synthesized in this way and used in the present invention is 2
or 3; 5- or 6-dichlorocarbonyl-perhylonorporene and its methyl substituted derivatives (e.g.

[Formula]), 2 or 3; 6 or 7-dichlorocarbonyl-perhydro-
1,4-Methanonaphthalene and its methyl substituted derivatives (e.g.

[Formula]), 2 or 3; 6 or 7-dichlorocarbonyl-perhydroanthracene and its methyl substituted derivatives (e.g.

[Formula]), 2 or 3; 6 or 7-dichlorocarbonyl-perhydro-1,4; 5,8-dimethanonaphthalene and its methyl substituted derivatives (e.g.

[Formula]), 2 or 3; 6 or 〓〓〓〓
is 7-dichlorocarbonyl-perhydro-1,
4;5,8;9,10-trimethanoanthracene and its methyl substituted derivatives (e.g.

Dicarbonyl halides of polyalicyclic compounds having at least two shared carbon atoms such as [Formula]) and similar perhydroindenes, perhydro-4,7-methanoindenes,
The compound is selected from dicarbonyl halides of perhydrofluorene, perhydroacenaphthylene, perhydrofluoranthene, perhydropyrene, etc. and derivatives thereof. These polyalicyclic dicarbonyl halides are brought into contact with polyamine thin films using a solution contact method, which is very effective. Solvents that can be selected to prepare a homogeneous solution of this polycycloaliphatic dicarbonyl halide have a solubility parameter δ of 6.9 to 8.7.
Solvents that are difficult to form hydrogen bonds in the range of be done. The preferred concentration of polycyclodicarbonyl halide in these solvents is 0.01 to 10 mmol/
l-solvent, and within this range, a uniform solution can be obtained, and a preferable rejection rate can be obtained from the characteristics of the crosslinked polyamine thin film, and at the same time, a stable thin film without defects such as pinholes and shrinkage can be obtained. can be manufactured. If a solvent with a solubility parameter outside the above range is used, such as an aromatic solvent or a polar solvent, when it comes into contact with the polyamine thin film, the thin film will shrink almost instantly and the formation of pinholes that can be seen with the naked eye may be observed, making it unsuitable for use. A durable composite membrane cannot be obtained. This is extremely important in the sense that a solution contact method, which is highly advantageous in terms of membrane performance and industrially, can be used when contacting with the polycycloaliphatic dicarbonyl halide polyamine thin film of the present invention. That is, one of the characteristics of using the polyalicyclic dicarbonyl halide used in the present invention as a crosslinking agent is that a solution contact method can be used especially when contacting with the amino group or imino group of the polyamine thin film. Therefore, it is possible to supply a thin film in a stable state without pinholes, etc., which are fatal defects for a semipermeable membrane with an excellent rejection rate. Another feature of the present invention comes into its own when evaluating the performance of semipermeable membranes. That is, when an aqueous solution in which polar organic molecules and inorganic salts are dissolved is permeated through the semipermeable membrane of the present invention, the permeation flux exhibiting a certain predetermined rejection rate is extremely large, and it also exhibits a high degree of selectivity for polar organic molecules. This is the point shown. In addition to this, another feature of the present invention is that the permeation flux is reduced by the hot water cleaning method to prevent adhesion of floating solids on the membrane surface and pore clogging, which are problems during industrial use. can be easily recovered, and no matter how many times this hot water washing is repeated, there is no change in the above-mentioned preferable high selectivity and high flux. It is not clear why the polyamine composite membrane of the present invention using the polyalicyclic dicarbonyl halide as a crosslinking agent selectively removes or recovers polar organic compounds from among the polar organic compounds and inorganic salts dissolved in water. . However, in comparison with cases where aromatic or aliphatic dicarbonyl halides are used as crosslinking agents, it has been found that when the crosslinked ultra-thin film layer on the surface of a polyamine thin film is observed at the molecular level, the crosslinking agent bonded to the polyamine is Stereochemical properties,
In other words, the reason seems to be the anisotropy within the ultra-thin film layer. In view of the intent of the present invention, it will be apparent that minor modifications or grafts or copolymers of polyamines are within the scope of the present invention. For example, the free amino groups of the polyamine could be subjected to alkylation, cyanoethylation, formalization, carbamoylation, acylation, hydroxylation, mercaptalization, etc. before or after composite membrane production. Furthermore, focusing on the fact that these polyamines can be obtained by ring-opening polymerization, ring-opening copolymerization or the like can also be attempted. Attempts to increase the selectivity for molecules to be captured by slight changes such as changing the methyl group of the polyalicyclic group used in the present invention to a tertiary butyl group belong to the scope of the present invention. Next, the present invention will be specifically explained using examples. Example 1 Polysulfone (UCC product P-3500) 15
% dimethylformamide solution onto one end of a clean glass plate (14 x 55 x 0.5 cm) with a width of 13.6 cm.
〓〓〓〓
Casting was performed using a casting blade with a gate part of 9.9 cm and a gap of 0.2 mm for about 2 seconds, followed by a coagulation bath [deionized water containing 3% dimethylformamide and 0.5% sodium dodecyl sulfate (Cadotte,
JE et al., PB Report, 229.337.234.198)]. After 5 minutes, the glass plate is removed from the coagulation bath and washed by immersing it in a deionized water bath (repeat 3 times). Place the wet polysulfone support that has been peeled off from the glass plate on a stainless steel plate.
Polyethyleneimine (Nippon Shokubai product P-
Pour a 1% aqueous solution of 1000) onto it. After 10 minutes of immersion, the polyethyleneimine aqueous solution was poured out, and the stainless steel dish was held vertically for 1 minute to drain off the excess polyethyleneimine aqueous solution. On this wet polyethyleneimine thin film, 2 or 3; 6 or 7-dichlorocarbonyl-perhydro-1,4; 8,5-naphthalene as a crosslinking agent is added.

Pour in a hexane solution (concentration 20mmol/l-hexane) of [formula].
After 1 minute the solution is poured off and kept at an angle in a forced air oven (105°C) for 10 minutes. It was taken out of the oven and left to cool, and a test composite film with a diameter of 6 cm was cut out using a mold and used for testing (for each concentration).
(10 sheets were prepared). The same operation was performed for the corresponding hexane solution of dimetainoisocyanate (the concentration was the same as above), and 10 test composite membranes were prepared for each concentration. Using the composite membrane obtained in this way,
Contains 5000ppm of CaCl ₂ , 1000ppm of naphthalene sulfonic acid soda formalin condensate (abbreviated as NASF), and 20ppm of suspended solids mainly composed of styrene-butadiene copolymer rubber (passed through Millipol filter 5 microns, did not pass 0.45 microns) Long-term reverse osmosis experiments were conducted on aqueous solutions. Continuous reverse osmosis experiments were conducted using the Tokyo Kogyo Trial Model (Water Treatment Experimental Method,
550 pages, published by Corona Publishing, 1971). Under the conditions of the effective area of the membrane 8.60cm ² , the flow rate of the original test liquid (per membrane) 20l/hr, and the operating pressure 40Kg/cm ² ,
Both the residual liquid and permeate liquid were returned to the stock liquid tank, and continuous operation was performed for 30 days, and the permeation flux and rejection rate were measured. The temperature of the stock solution was adjusted so that it passed through the membrane surface at a temperature of 30°C. The results are shown in Table 1. Table 2 shows the results when the stock solution was kept at a temperature of 60°C for 1 hour twice a day to also wash the membrane surface with hot water.

[Table] From the results in Table 1, it can be seen that the membrane crosslinked with the polyalicyclic dicarbonyl chloride of the present invention can selectively eliminate polar organic molecules with a high rejection rate from an aqueous solution in which polar organic molecules and inorganic salts coexist. I understand. still,
The decrease in permeation flux and selective exclusion over time is due to the adhesion of suspended solids in the test liquid to the membrane surface.

[Table] After 30 days of the test listed in Table 1, we tried acid cleaning (6% citric acid aqueous solution, 1 hour at 30°C) and low pressure flashing (operating pressure 5 kg/cm ² for 1 hour). Recovery of permeation flux is only 10%〓〓〓〓
Ivy. When hot water washing is performed, the permeation flux decreases only slightly even after 30 days, which is sufficient for practical use. Furthermore, it can be seen that the rejection rates of Ca Cl ₂ and NASF in the present invention maintain satisfactory values and high selectivity without decreasing due to continuous operation. However, in the case of the comparative example, the rejection rate of both substances decreased as the operating time increased, and the membrane further deteriorated, and the measurement results after 30 days showed that it could no longer be used for practical use. Production Example A polyether polyamine was prepared by the following operation. Charge 1.4 mL of pre-dehydrated epichlorohydrin and 630 mL of benzene into a No. 3 polymerization flask equipped with a stirrer. Attach the flask to a heating bath and adjust the flask internal temperature to 50°C. When the temperature is adjusted to 50°C, a benzene solution of SnCl ₄ as a polymerization catalyst is added dropwise through the dropping funnel. Since the dropwise addition of the catalyst generated heat, a total of 35 mmol was added little by little over 5 hours. After the dropwise addition was completed, the reaction was continued for another 2 hours, and 10 ml of methanol was added to stop the polymerization reaction. Add more water-methanol NaOH solution to remove catalyst residue. After diluting the contents of the flask with benzene, the catalyst residue in the polymer cement is adsorbed and separated using Celite-560. After concentration using a rotary evaporator and vacuum drying, 890 gr of polyepichlorohydrin was recovered. The number average molecular weight measured by the VPO method was 4200. 93 gr of this polyepichlorohydrin is dissolved in 93 gr of dimethylformamide and 90 gr of ethylenediamine. Keep the melting temperature at 100°C and stir for 5 hours.
After cooling to 30°C, 135g of 30% NaOH aqueous solution is added, and stirring is continued at this temperature for another night. 117 gr of ethylene diamined polyepichlorohydrin was recovered by vacuum drying. Example 2 A 1% aqueous solution of ethylene diamined polyepichlorohydrin prepared in Preparation Example is passed through No. 2 paper and then poured onto a polysulfone support prepared in the same manner as in Example 1. After 10 minutes of immersion, the aqueous solution was removed and 2 or 3;6 or 7-dichlorocarbonyl-perhydro-1,4-9,10-dimethanoanthracene was added as a crosslinking agent. Hexane solution (6.0m mol/l-hexane) of
After contacting for 10 minutes and removing the solution, it was heated for 10 minutes in an open forced air circulation system (110° C.) to produce a composite membrane for testing. Similarly, composite membranes using 2 or 3; 6 or 7-dimethanoisocyanate-perhydro-1,4; 9,10-dimethanoanthracene as the crosslinking agent were also prepared. The test liquid used was actual wastewater from the outlet of an activated sludge tank at a synthetic rubber factory. NaCl as the main component as an inorganic salt
and a mixture of CaCl ₂ , Al ₂ SO ₄ , NaClO 6000ppm,
The COD component consisted of unreacted monomers and other organic compounds, and it contained 100 ppm of suspended solids, mainly consisting of the residue of 100 ppm activated sludge. Under the same conditions as the hot water cleaning in Example 1,
It was operated continuously for several days. The results are shown in Table 3. The concentration of the inorganic salt was determined from the measurement of specific conductivity, and since NaCl is the main component, it is expressed as NaCl.

[Table] Each value in Table 3 is calculated by measuring the permeation flux after 1 hour for each of the 10 membranes.
The average of six measured values excluding the runner-up, minimum, and runner-up values is calculated, and the measurement results are shown for a membrane that showed a value as close as possible to this value when continuous operation was continued. From the results in Table 3, in the case of the comparative example, twice a day,
While the permeation flux and rejection rate change after 1 hour of hot water washing, there is almost no change in the inventive example, and unlike the comparative example, it is sufficiently resistant to a type of deterioration caused by hot water washing. I can see what I'm getting. In order to make wastewater meet environmental standards, and
Whatever the goal for the recovery of COD components,
In the comparative example, the degree of achievement is unstable, whereas in the example of the present invention, a stable degree of achievement is obtained. Therefore,
It is easy to establish wastewater operation standards, and the amount and quality of recovered COD components are always constant, making it easy to plan wastewater reuse or create a closed system. 〓〓〓〓

Claims (1)

[Claims] 1. A polyamine thin film on a liquid-permeable porous support is brought into contact with a polyalicyclic dicarbonyl halide capable of reacting with the amino group or imino group of this polyamine to cause crosslinking. A method for manufacturing a semipermeable membrane. 2. The method for producing a semipermeable membrane according to claim 1, wherein the polyamine thin film is brought into contact with a solution of polycycloaliphatic dicarbonyl halide. 3. The method for producing a semipermeable membrane according to claim 2, wherein the polyalicyclic dicarbonyl halide is used as a solution in a solvent having a solubility parameter in the range of 6.9 to 8.7.