KR20230149084A - Method for manufacturing nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and nanofiber separation membrane for water treatment prepared thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and to a nanofiber separation membrane for water treatment produced thereby. More specifically, it is manufactured by mixing and heating a polyvinyl chloride solution and a polyethyleneimine solution. It relates to a manufacturing method for producing a nanofiber separator for water treatment by electrospinning the mixed solution and a nanofiber separator for water treatment manufactured thereby.

Description

Method for manufacturing nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and nanofiber separation membrane for water treatment prepared thereby thereby}

The present invention relates to a method for manufacturing a nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and to a nanofiber separation membrane for water treatment produced thereby. More specifically, it is manufactured by mixing and heating a polyvinyl chloride solution and a polyethyleneimine solution. It relates to a manufacturing method for producing a nanofiber separator for water treatment by electrospinning the mixed solution and a nanofiber separator for water treatment manufactured thereby.

Plastics such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) are highly durable, lightweight, and inexpensive materials for packaging, construction, and other materials. It is widely used in construction, transportation, etc. However, plastic quickly becomes waste material and enters the environment. The accumulated plastic waste on Earth from 1950 to 2015 is 6.3 billion tons, of which 60% is estimated to have accumulated in landfills or the natural environment. Plastic waste accumulated in the environment threatens the overall safety of marine, freshwater and soil habitats and the food chain. Accordingly, Canada, Peru and 170 UN member states have taken or are preparing to take action against plastic pollution.

Current techniques for plastic waste management include physical treatment methods, thermal/chemical treatment methods, and biological treatment methods. However, most methods are not suitable for the treatment of PVC plastic waste or are not effective, so they have been disposed of by landfill and incineration. PVC is a chlorine-rich plastic, with 57% of its weight made up of chlorine molecules. Therefore, PVC waste incineration has been problematic due to the formation of dioxins, which are highly toxic persistent organic pollutants (POPs). Landfilling is the least preferred method of waste management and in many countries landfilling is not permitted due to increasing costs, lack of space and migration of toxic additives from PVC products into environmental media. Therefore, finding sustainable methods for recycling PVC waste is a very important issue.

Water-related problems are among the most pressing environmental problems we face today, and they are worsening as the population grows, with reports that around half of the world's population will face water scarcity by 2025. Direct discharge of industrial wastewater into surface water without proper treatment is one of the serious causes of water problems. Industrial effluents contain various organic substances such as synthetic dyes, chlorophenol, dibenzofuran, and polychlorinated biphenyls (PCBs), as well as inorganic pollutants such as heavy metals, arsenic, phosphates, and nitrates. Among these, synthetic dyes are considered one of the main causes of water pollution. Most industries use dyes, and untreated industrial wastewater contains large amounts of synthetic dyes. However, synthetic dyes are toxic and carcinogenic, so wastewater discharged into the environment without proper treatment poses a serious risk to the aquatic ecosystem and human health.

Various technologies, including coagulation, adsorption, photolysis, membrane filtration, electrochemical oxidation, and ion exchange, have been applied to dye wastewater treatment. Among these methods, adsorption and membrane filtration are effective means to remove dyes from wastewater. Adsorption has the advantage of being low cost, efficient with low energy consumption, and easy to operate.

In order to solve the above problems of the present invention, the purpose of the present invention is to provide a method for manufacturing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and a nanofiber membrane for water treatment manufactured thereby.

In addition, the purpose of the present invention is to provide the properties of a separation membrane with optimal treatment capacity for wastewater containing Cibacrone Brilliant Yellow 3G-P, a widely used reactive dye.

The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description of the present invention. will be.

In order to achieve the above object, the present invention provides a method for manufacturing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and a nanofiber membrane for water treatment produced thereby.

The present invention includes a mixing step of mixing a polyethyleneimine solution and a polyvinyl chloride solution and then heating to prepare a mixed solution; An electrospinning step of producing a composite nanofiber separator by electrospinning the mixed solution; and a drying step of washing and drying the composite nanofiber membrane. It provides a method of manufacturing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride.

In the present invention, the mixing step is performed by adding polyvinyl chloride and polyethyleneimine to a solvent prepared by mixing dimethylformamide and tetrahydrofuran in a 1:1 volume ratio to prepare a polyethyleneimine solution and a polyvinyl chloride solution. , the polyvinyl chloride solution and the polyethyleneimine solution are mixed and then heated to a temperature of 80 to 100° C. to prepare a mixed solution.

In the present invention, the mixed solution is characterized in that it contains 30 to 70 parts by weight of the polyethyleneimine solution and 30 to 70 parts by weight of the polyvinyl chloride solution relative to 100 parts by weight of the mixed solution.

In the present invention, the electrospinning step is performed by electrospinning the mixed solution, which is transported at a solution transfer rate of 0.2 to 1.0 mL/h using a syringe pump, at 20 to 30 kV through the needle of the syringe pump to produce a nanofiber separator. It is characterized by:

In the present invention, the electrospinning step is characterized by controlling the fiber diameter of the nanofiber separator to 450 nm or less.

The present invention provides a nanofiber membrane for water treatment manufactured by the nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride.

The nanofiber separation membrane for water treatment of the present invention includes a separation membrane substrate; and a nanofiber separator for water treatment including a cross-linking group of polyethyleneimine and polyvinyl chloride on at least a portion of the surface of the separator substrate.

In the present invention, the separator is characterized by having a porous structure in which the nanofibers constituting the separator have a diameter of 50 to 450 nm.

In the present invention, the separator is characterized in that the polyethyleneimine and the polyvinyl chloride are cross-linked to expose amine groups on the surface of the separator.

In the present invention, the separation membrane is characterized by selectively adsorbing anionic contaminants.

In the present invention, the separator is characterized in that it can be applied even at high temperatures of 130 to 180°C.

In the present invention, the separator is characterized by an average stress of 6.32 to 8.96Mpa and a strain rate of 786.02 to 1082.26%.

In the present invention, the separator is characterized as being hydrophilic in that the water contact angle at room temperature decreases from 101.6 to 122.4° to 7.8 to 10.2° over 10 to 20 seconds.

In the present invention, the separation membrane is characterized by a zeta potential pHpzc of 8.8 to 12.8.

In the present invention, the separation membrane is characterized by an average pure water permeation flux of 2553 to 3053 L/m ² μh.

In the present invention, the separation membrane is characterized in that it can purify anionic dye at pH 1 to 12.

In the present invention, the separation membrane is characterized in that it can be reused 2 to 4 times by desorbing and re-adsorbing contaminants.

Hereinafter, this specification will be described in more detail.

As a means of solving the above problem, the present invention provides a method for manufacturing a nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, and a reusable separation membrane for water treatment with adsorption through the nanofiber separation membrane for water treatment manufactured thereby. can do.

In addition, by imparting adsorption according to the present invention, it is possible to provide a separation membrane for water treatment that is capable of separating and removing reactive dyes that cannot be removed by existing separation membranes.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Figure 1 is a schematic diagram showing (a) PEI/PVC preparation by electrospinning and (b) filtration system.
Figure 2 is a graph showing the FTIR spectra of PVCM and PEI/PVCM.
Figure 3 is a graph showing the FE-SEM images of (a) PVCM and (b) PEI/PVCM and the nanofiber diameter distribution of (c) PVCM and (d) PEI/PVCM.
Figure 4 is a graph showing the TGA and (b) DTG curves of (a) PVCM and PEI/PVCM.
Figure 5 is a graph showing the stress strain curve of PEI/PVCM.
Figure 6 is a graph showing the water contact angle of PVCM and PEI/PVCM.
Figure 7 is a graph showing the zeta potential of PVCM and PEI/PVCM.
Figure 8 is a graph showing the breakthrough curve of PEI/PVCM for adsorption separation of Cibacron Brilliant Yellow 3G-P from simulated wastewater at various pH.
Figure 9 is a graph showing the reusability of PEI/PVCM for three cycles of adsorption of Cibacron Brilliant Yellow 3G-P at pH 7.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present invention, but this may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the relevant invention. Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than simply the name of the term.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

The numerical range includes the values defined in the range above. Any maximum numerical limit given throughout this specification includes all lower numerical limits as if the lower numerical limit were explicitly written out. Every minimum numerical limit given throughout this specification includes every higher numerical limit as if such higher numerical limit were expressly written out. All numerical limits given throughout this specification will include all better numerical ranges within the broader numerical range, as if the narrower numerical limits were clearly written.

Below, examples of the present invention will be described in detail, but it is obvious that the present invention is not limited to the following examples.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

Method for manufacturing nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride

The present invention relates to a method for manufacturing a nanofiber separation membrane for water treatment containing polyethyleneimine (PEI) and polyvinyl chloride (PVC). A mixing step of preparing a mixed solution by heating; Electrospinning step of producing a composite nanofiber separator by electrospinning the mixed solution; And a drying step of washing and drying the composite nanofiber separator.

In the mixing step of the present invention, polyvinyl chloride and polyethyleneimine are added to a solvent prepared by mixing dimethylformamide and tetrahydrofuran in a 1:1 volume ratio to prepare a polyethyleneimine solution and a polyvinyl chloride solution, and then A mixed solution can be prepared by mixing the polyvinyl chloride solution and the polyethyleneimine solution and heating to a temperature of 80 to 100°C.

The mixed solution of the present invention may contain 30 to 70 parts by weight of the polyethyleneimine solution and 30 to 70 parts by weight of the polyvinyl chloride solution, based on 100 parts by weight of the mixed solution. Preferably, the mixed solution may include 50 to 70 parts by weight of the polyethyleneimine solution and 30 to 50 parts by weight of the polyvinyl chloride solution, based on 100 parts by weight of the mixed solution. More preferably, the mixed solution may contain 60 parts by weight of polyethyleneimine and 40 parts by weight of the polyvinyl chloride solution based on 100 parts by weight of the mixed solution.

In the electrospinning step of the present invention, a nanofiber separator can be produced by electrospinning the mixed solution, which is transported at a solution transfer rate of 0.2 to 1.0 mL/h using a syringe pump, at 20 to 30 kV through a needle of a syringe pump. there is. Preferably, the transfer rate of the solution may be 0.3 to 0.7 mL/h.

The electrospinning step of the present invention can control the fiber diameter of the nanofiber separator to 150 nm or less. Preferably, the fiber diameter of the nanofiber separator can be controlled to 250 nm or less. The separation membrane can separate water and reactive dye from the reactive dye aqueous solution.

Nanofiber membrane for water treatment

The present invention relates to a nanofiber separation membrane for water treatment. The present invention relates to a mixing step of mixing a polyethyleneimine solution and a polyvinyl chloride solution and then heating to prepare a mixed solution; Electrospinning step of producing a composite nanofiber separator by electrospinning the mixed solution; and a drying step of washing and drying the composite nanofiber separator.

The mixing step of the present invention involves adding polyvinyl chloride and polyethyleneimine to a solvent prepared by mixing dimethylformamide (DMF, N,N-Dimethylmethanamide) and tetrahydrofuran (THF, Tetrahydrofuran) in a 1:1 volume ratio. After preparing the polyethyleneimine solution and the polyvinyl chloride solution, the polyvinyl chloride solution and the polyethyleneimine solution can be mixed and heated to a temperature of 80 to 100° C. to prepare a mixed solution.

The mixed solution of the present invention may contain 30 to 70 parts by weight of the polyethyleneimine solution and 30 to 70 parts by weight of the polyvinyl chloride solution, based on 100 parts by weight of the mixed solution. Preferably, the mixed solution may include 50 to 70 parts by weight of the polyethyleneimine solution and 30 to 50 parts by weight of the polyvinyl chloride solution, based on 100 parts by weight of the mixed solution. More preferably, the mixed solution may contain 60 parts by weight of polyethyleneimine and 40 parts by weight of the polyvinyl chloride solution based on 100 parts by weight of the mixed solution.

In the electrospinning step of the present invention, a nanofiber separator can be produced by electrospinning the mixed solution, which is transported at a solution transfer rate of 0.2 to 1.0 mL/h using a syringe pump, at 20 to 30 kV through a needle of a syringe pump. there is. Preferably, the transfer rate of the solution may be 0.3 to 0.7 mL/h.

The electrospinning step of the present invention can control the fiber diameter of the nanofiber separator to 150 nm or less. Preferably, the fiber diameter of the nanofiber separator can be controlled to 250 nm or less. The separation membrane can separate water and reactive dye from the reactive dye aqueous solution.

The present invention relates to the nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride manufactured by the method for producing a nanofiber separation membrane for water treatment containing polyethyleneimine and polyvinyl chloride, which includes a separation membrane substrate; And it may include a cross-linking group of polyethyleneimine and polyvinyl chloride on at least a portion of the surface of the separator substrate.

The separator of the present invention may have a diameter of 50 to 450 nm of nanofibers constituting the separator and may have a porous structure. Preferably, the nanofiber diameter may be 100 to 250 nm. More preferably, the nanofiber diameter may be 180 nm.

The separator of the present invention can expose amine groups on the surface of the separator through cross-linking of the polyethyleneimine and the polyvinyl chloride.

The separation membrane of the present invention can selectively adsorb anionic contaminants. Unlike existing commercially available separators, the separator improves the performance of the separator by providing adsorption and may be able to separate and remove reactive dyes that cannot be removed by existing separators. This allows it to be competitive when applied to actual sewage/wastewater treatment processes. Preferably, the anionic contaminant may be a reactive dye including Cibacron Brilliant Yellow 3G-P.

The separator of the present invention can be applied even at high temperatures of 130 to 180°C.

The separator of the present invention may have an average stress of 6.32 to 8.96Mpa and a strain rate of 486.02 to 1082.26%.

The separator of the present invention may be hydrophilic in that the water contact angle at room temperature decreases from 101.6 to 122.4° to 7.8 to 10.2° for 10 to 20 seconds. The separator may have hydrophilicity due to the abundance of amine groups on the surface.

The separation membrane of the present invention may have a Zeta Potential pHpzc of 8.8 to 12.8.

The separation membrane of the present invention may have an average pure water flux of 2553 to 3073 L/m ² μh. The pure water permeate flux may be higher than that of a commercial separation membrane.

The separation membrane of the present invention can purify anionic dyes at pH 1 to 12. Preferably, the separation membrane is capable of purifying anionic dyes at pH 4 to 8.

The separation membrane of the present invention can be reused 2 to 4 times by desorbing and re-adsorbing contaminants.

[Materials and reagents]

Polyvinyl chloride (PVC, Mw=80,000), Cibacron Brilliant Yellow 3G-P, N-dimethylformamide (DMF, 99.5%), tetrahydrofuran (THF, 99%) and Branched Polyethyleneimine (PEI, Mw = 70,000, 50% (w/v) aq. soln.) was prepared. The water in the PEI was removed by vacuum freeze-drying before use in the experiment.

[Example 1] Preparation of PEI/PVC nanofiber membrane by electrospinning

DMF and THF were mixed at a volume ratio of 1:1 to prepare 200 mL of DMF/THF solution. Afterwards, 30 g of PEI and 10 g of PVC were dissolved in 100 mL of DMF/THF solution to prepare a 30 wt% PVI solution and a 10 wt% PVC solution, respectively.

After adding 15 mL of the 30 wt% PVI solution and 10 mL of the 10 wt% PVC solution to a 50 mL heat-resistant glass bottle, the bottle was sealed and placed in a water bath incubator set at 80°C and 160 rpm for 4 hours to form a PEI-crosslinked PVC solution. was manufactured. The prepared polymer solution was homogenized and then cooled to room temperature. Then, 10 mL of the solution was placed in a 12 mL plastic syringe with a stainless steel needle with a 90° tip and an inner diameter of 0.26 mm.

Electrospinning was performed by applying a DC high voltage of 25 kV to the polymer solution in the plastic syringe through the needle using a voltage generator. The syringe pump was installed on the nozzle traver at a speed of 1 cm/s, and the transfer speed of the solution was set to 0.5 mL/h using the syringe pump. The room temperature of electrospinning was 25 ± 1 °C and humidity was 40 to 50 °C. It was %. PEI/PVC nanofibers were collected at a distance of 15 cm on a flat plate collector covered with aluminum foil. The collected nanofibers were expressed as PEI/PVCM. A schematic diagram of the electrospinning preparation of PEI/PVCM is shown in Figure 1. The PEI/PVCM prepared after electrospinning was soaked in distilled water for 24 hours to remove reagents that did not react with the solvent, freeze-dried for 24 hours, and then stored in a dryer for further use.

[Comparative Example 1] Preparation of PVC nanofiber membrane by electrospinning

Comparative Example 1 was prepared in the same manner as Example 1, except by electrospinning 10 wt% of the PVC solution, and was expressed as PVCM.

[Experimental Example 1] FTIR analysis

The nanofiber membrane prepared according to Example 1 and Comparative Example 1 was analyzed using FTIR (Fourier transform infrared spectroscopy). The FTIR spectrum observation results of PVCM and PEI/PVCM are shown in Figure 2.

The characteristic peaks of PVC were observed at 2970 (CH stretching vibration of CHC ₁ ), 1247 and 1328 (CH strain vibration of CHC ₁ ), and 610 cm ^-1 (CC _l stretching vibration). The peak at 2910 cm ^-1 was assigned to the symmetric stretching vibration of -CH ₂ -. The peak at 1093 cm ^-1 is due to the stretching vibration of CC of the PVC main chain. After cross-linking with PEI, some peaks shifted to new positions, and new peaks appeared in the FTIR spectrum of PEI/PVCM. The peaks at 2910, 1328, and 1093 cm ^-1 increased in intensity to 2901, 1321, and 1065 cm ^-1 , which correspond to the new main chain (-CH ₂ ,-CH,CC) of PEI. The peak at 1247cm ^-1 was shifted to 1255cm ^-1 due to the formation of CN bond and overlapped with -CH ₂ . A peak at 3785 cm ^-1 was assigned to the -OH stretching vibration of the adsorbed water, and this was confirmed through TGA analysis. The peaks at 3300 and 1559 cm ^-1 are due to NH stretching and bending vibrations, respectively. The peak at 165c4m ^-1 is because -NH ₂ (amide I) and -NH (amide II) overlap. Therefore, it can be concluded that PEI was successfully combined with PVC.

[Experimental Example 2] FE-SEM analysis

The surface morphology of the nanofiber membrane prepared according to Example 1 and Comparative Example 1 was observed using FE-SEM (field emission scanning electron microscope). The SEM images were analyzed using fij ImageJ software to measure the nanofiber diameter, and six SEM images were analyzed for each membrane.

As a result of the measurement, the top surface shape and nanofiber diameter distribution histogram of PVCM and PEI/PVCM are shown in Figure 3. The top surfaces of PVCM and PEI/PVCM recorded at x5000 magnification appeared as shown in Figures 3(a) and (b). The nanofibers of the PVCM were randomly distributed and a uniform, bead-free mat with a porous structure was formed. Additionally, the PVC nanofibers were smooth and dispersed, whereas the PEI/PVCM nanofibers were relatively rough, closely packed together, and narrowly distributed.

Figures 3 (c) and (d) are graphs showing the nanofiber diameter distribution of PVCM and PEI/PVCM. The nanofiber diameter of PEI/PVCM showed a relatively narrow distribution compared to PVCM, and about 87% of the nanofibers were 100 to 250 nm. The average fiber diameter of PVCM was 380 to 1046 nm, and that of PEI/PVCM was 125 to 238 nm. This decrease in diameter is due to the amine groups in PEI increasing the polarity or free volume of the polymer.

[Experimental Example 3] Thermal stability analysis

The thermal stability curve of the nanofiber membrane prepared according to Example 1 and Comparative Example 1 was observed using TGA, and the DTG (thermal stability curve) was obtained by Origin 2021 software. Temperature scans were performed at 20°C/min from 50 to 800°C in a nitrogen atmosphere.

The thermal stability curves of PVCM and PEI/PVCM are shown in Figure 4a, and the derived thermogravimeter DTG curve is shown in Figure 4b. As shown in Figures 4a and 4b, PVCM had two thermal decomposition stages, and PEI/PVCM had three thermal decomposition stages. For PVCM, the first decomposition step with a mass loss of 63.23% occurred between 220 and 360 °C, and the DTG peak at 290 °C appeared due to dechlorination of the PVC molecular chain. The second mass loss step ranged from 400 to 525 °C (DTG peak at 463 °C) and accounted for 27.44% of the mass loss. This mass reduction occurred due to C-C bond breaking, cyclization, and formation of aromatic compounds. PEI/PVCM had a mass loss of 1.96% at 50 to 150°C due to evaporation of adsorbed water prior to the first decomposition step. The first degradation step, accounting for 45.30% of the mass loss, ranged from 156 to 300 °C, with a DTG peak at 236 °C. This mass loss was caused by the decomposition of the amino groups of the PEI molecular chain due to the gradual dechlorination of PVC. The DTG peak of PEI/PVCM appeared at a much lower temperature than that of PVCM, because PVI significantly reduced the thermal stability of PVC. Stage 2 at 14.57% mass loss ranged from 310 to 400 °C (DTG peak at 360 °C), corresponding to further dechlorination of PVC. The third step, accounting for 25.77% of the mass loss, was between 410 and 540 °C and the DTG peak was at 470 °C, which could be assigned to the degradation of PVC and PEI backbones. The overall thermal stability analysis results showed that PEI/PVCM was stable up to 150°C without decomposition. Therefore, PEI/PVCM can be applied to high-temperature wastewater treatment.

[Experimental Example 4] Tensile analysis

The film thickness of the nanofiber membrane prepared according to Example 1 and Comparative Example 1 was measured using a portable digital micrometer. The mechanical properties of the membrane were performed using a universal tensile tester under asymmetric strain. All membrane samples were cut into a dumbbell shape with a size of 50 mm x 100 mm, the initial length between clamps was set to 5 mm, and the stretching speed was maintained at 100 mm/min.

As a result of measuring the thickness of each PEI/PVCM three times before the tensile test, the average thickness of PEI/PVCM was 120 ± 2 μm. To evaluate the mechanical strength of the membranes, tensile tests were performed on three membrane samples, and their stress-strain curves are shown in Figure 5. The average stress of PEI/PVCM was 7.64 ± 0.32 MPa, and the average strain was 934.14 ± 48.12%, which was higher than that of commercial membranes. Therefore, the PEI/PVCM prepared in this study can be applied industrially.

[Experimental Example 5] Membrane hydrophilicity

The water contact angle (WCA) of the nanofiber membrane prepared according to Example 1 and Comparative Example 1 at room temperature was tested by dropping a 15 μL water drop on the membrane surface using a contact angle meter. All samples were tested five times and the average value was obtained. WCA measurement was performed to confirm the hydrophilicity of PVCM and PEI/PVCM.

The WCA of PVCM and PEI/PVCM were measured three times each, and the results are shown in Figure 6. PVCM was shown to be hydrophobic with a WCA of 131.8 to 133.2°. Conversely, the WCA of PEI/PVCM decreased from 111.6 to 112.4° to 8.8 to 9.2° within 16 seconds, indicating that PEI/PVCM was hydrophilic. This phenomenon is because the hydrophobic surface of PVCM was converted into a hydrophilic surface by introducing a large hydrophilic group (-NH ₂ ) during the manufacturing process of PVCM.

[Experimental Example 6] Zeta potential analysis

The zeta potential of the nanofibrous membrane prepared according to Example 1 and Comparative Example 1 at various pH was measured using a zeta potential analyzer.

The zeta potentials of PVCM and PEI/PVCM at different pH values are shown in Figure 7. When the pH value was below 12, the zeta potential of PVI/PVCM was much higher than that of PVCM. In particular, the zeta potential of PVCM and PEI/PVCM decreased from 12.44 to -36.07mV and 55.67 to -27.73mV, respectively, and the pH value increased from 2 to 12. The pHpzc (pzc: point of zero charge) of PVCM was 3.1, and the pHpzc of PEI/PVCM increased significantly to 10.8. The significant increase in pHpzc of PEI/PVCM is due to the abundant amino groups of PEI. When pHpzc (10.8) is high, the surface of PEI/PVCM is positively charged below pH10.8, which is advantageous for anionic dye adsorption over a wide range of pH.

[Experimental Example 7] Pure water permeation flux of PEI/PVCM

The pure water permeation flux with an effective membrane area of 8.55 cm ² was measured through a filtration test device for the nanofiber membrane prepared according to Example 1. PEI/PVCM was pre-pressurized with distilled water for 60 minutes to obtain a constant water flow rate and then measured for 10 minutes. Three membranes were used in the water flux test, and each membrane was tested five times. The water velocity of each membrane is calculated from five measurement data, and the final water velocity of the membrane is the average of the water velocity of the three membranes. The flow rate of the mule (Jw, L/m ² hh) was calculated according to Equation 1 below.

Equation 1

Here, V(L) is the permeate volume, A(m ² ) is the effective membrane area, and Δt(h) is the permeate time.

As a result of testing the pure water permeate flux of the three membranes, the average pure water permeate flux (Jw) was 3013 ± 60 L/m ² μh, which was much higher or almost the same as that of the previously reported commercial PEI microfiltration membrane.

[Experimental Example 8] Dynamic adsorption characteristics of PEI/PVCM

The dynamic adsorption capacity of the nanofiber membrane prepared according to Example 1 was performed at room temperature through a total filtration system. In all adsorption experiments, a 10 ppm Cibacron Brilliant Yellow 3G-P solution, which simulated dye wastewater, was used as a feed solution. Each membrane tested was pressurized with distilled water at 0.1 MPa, and the permeation flux of Cibacron Brilliant Yellow 3G-P at 0.1 MPa was examined after the voltage.

The flow rate (corresponding to the permeate flow rate) was maintained at 43 ± 1 mL/min at a pressure of approximately 0.1 MPa, and a membrane disk with an effective area of 8.55 cm ² was used in the filtration experiment. The effect of solution pH on dye removal was evaluated in the pH range from 4 to 9, and the breakthrough curve is shown in Figure 8.

As shown in Figure 8, the dashed line indicates that the residual dye concentration (Ct) in the effluent has reached 5% of the initial dye concentration (C ₀ ), which is the breakthrough point typically seen in fixed-bed column adsorption experiments, which is Ct/C ₀ = 0.5. Therefore, in this experiment, the breakthrough point was found to be Ct/C ₀ = 0.5.

When the pH increased from 4 to 9, a breakthrough point occurred in the filtration of the first 1691, 1050, 711, and 186 mL of solution, and the removal rate was higher than 95%, respectively, while the remaining Cibacrone Brilliant Yellow 3G-P in the permeate was reduced. The concentration was insufficient. This means that the dye concentration in the permeate solution meets the wastewater treatment standards of all countries. Therefore, PEI/PVCM has excellent removal efficiency of Cibacron Brilliant Yellow 3G-P at pH 4 to 8, indicating that it can purify a large amount of dye wastewater in this pH range, which is essential for industrial use.

[Experimental Example 9] Reusability of PEI/PVCM

The reusability of the nanofibrous membrane prepared according to Example 1 was evaluated by three repeated adsorption-desorption cycles at pH 7. In the desorption process, the dye-loaded membrane was eluted in 300 mL of 0.01 mol/L NaOH solution. Afterwards, the membrane was washed three times with deionized water and then underwent a dynamic adsorption process. The dye concentration before and after filtration was measured at a maximum wavelength of 404 nm using a UV-Vis spectrophotometer.

The reusability of PEI/PVCM was measured by repeating the dynamic adsorption process three times, and the results are shown in Figure 9. As shown in Figure 9, about 1050 mL of dye wastewater could be treated through PEI/PVCM to meet the discharge standards in the first adsorption cycle. The treatment capacity of PEI/PVCM for dye wastewater slightly decreased to about 1000mL in the second cycle and was relatively stable in the third cycle. This indicates that PEI/PVCM can be reused in reactive dye wastewater treatment.

Claims (17)

A mixing step of mixing a polyethyleneimine solution and a polyvinyl chloride solution and then heating to prepare a mixed solution;
An electrospinning step of producing a composite nanofiber separator by electrospinning the mixed solution; and
A method of manufacturing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride, including a drying step of washing and drying the composite nanofiber membrane.
According to clause 1,
The mixing step is,
Polyvinyl chloride and polyethyleneimine were respectively added to a solvent prepared by mixing dimethylformamide and tetrahydrofuran in a 1:1 volume ratio to prepare a polyethyleneimine solution and a polyvinyl chloride solution,
A method of producing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride, characterized in that the mixed solution is prepared by mixing the polyvinyl chloride solution and the polyethyleneimine solution and heating to a temperature of 80 to 100 ° C.
According to clause 1,
The mixed solution is,
Manufacturing a nanofiber-treated separator for water treatment containing polyethyleneimine and polyvinyl chloride, characterized in that it contains 30 to 70 parts by weight of the polyethyleneimine solution and 30 to 70 parts by weight of the polyvinyl chloride solution relative to 100 parts by weight of the mixed solution. method.
According to clause 1,
The electrospinning step is,
Polyethyleneimine and polychloride, characterized in that the nanofiber separator is produced by electrospinning the mixed solution at 20 to 30 kV through the needle of the syringe pump using a syringe pump at a solution transfer rate of 0.2 to 1.0 mL/h. Method for manufacturing nanofiber-treated separator for water treatment containing vinyl.
According to clause 1,
The electrospinning step is,
A method of manufacturing a nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride, characterized in that the fiber diameter of the nanofiber membrane is controlled to 450 nm or less.
A nanofiber membrane for water treatment containing polyethyleneimine and polyvinyl chloride prepared by the method of claim 1.
The nanofiber separation membrane for water treatment is,
Separator substrate; and
A nanofiber separator for water treatment comprising a cross-linking group of polyethyleneimine and polyvinyl chloride on at least a portion of the surface of the separator substrate.
According to clause 7,
A nanofiber separator for water treatment, characterized in that the separator has a porous structure where the nanofibers constituting the separator have a diameter of 50 to 450 nm.
According to clause 7,
The separator is a nanofiber separator for water treatment, characterized in that the polyethyleneimine and the polyvinyl chloride are cross-linked to expose amine groups on the surface of the separator.
According to clause 7,
The separation membrane is a nanofiber separation membrane for water treatment, characterized in that it selectively adsorbs anionic contaminants.
According to clause 7,
The separation membrane is a nanofiber separation membrane for water treatment, characterized in that it can be applied even at high temperatures of 130 to 180 ° C.
According to clause 7,
The separator is a nanofiber separator for water treatment, characterized in that the average stress is 6.32 to 8.96Mpa and the strain rate is 786.02 to 1082.26%.
According to clause 7,
The separator is a nanofiber separator for water treatment, characterized in that the water contact angle at room temperature decreases from 101.6 to 122.4 ° to 7.8 to 10.2 ° for 10 to 20 seconds.
According to clause 7,
The separation membrane is a nanofiber separation membrane for water treatment, characterized in that the zeta potential pHpzc is 8.8 to 12.8.
According to clause 7,
The separation membrane is a nanofiber separation membrane for water treatment, characterized in that the average pure water permeation flux is 2553 to 3053 L/m ² μh.
According to clause 7,
A nanofiber separator for water treatment, characterized in that the separator is capable of purifying anionic dye at pH 1 to 12.
According to clause 7,
The separator is a nanofiber separator for water treatment, characterized in that it can be reused 2 to 4 times by desorbing and re-adsorbing contaminants.