Polyaniline modified microporous aeration membrane and preparation method thereof

Abstract

The invention discloses a polyaniline modified microporous aeration membrane and a preparation method thereof, the polyaniline modified microporous aeration membrane comprises a first layer of base membrane, a second layer of microporous membrane and a third layer of modification layer, and aims to solve the problems of membrane pore blockage, hydrophobicity reduction and the like caused by microbial pollution in use of a hydrophobic microporous membrane. According to the technical scheme, the aeration membrane is characterized in that membrane holes of a microporous membrane are modified with polyaniline, so that the microporous membrane is free of holes and capable of permeating oxygen, the microporous membrane is a high-molecular organic membrane such as a polytetrafluoroethylene membrane and a nylon membrane, micropores of 0.1-2 microns are distributed in the surface of the microporous membrane, and the prepared aeration membrane has good air permeability and biological adhesiveness.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a microporous aeration membrane and a preparation method thereof. Background Art

[0002] Membrane Aerated Biofilm Reactor technology is a new water pollution control technology that combines efficient membrane aeration with biological treatment. It uses dense or microporous breathable membranes to aerate the membrane bioreactor and supply oxygen to the biofilm attached to the surface of the hollow fiber membrane. In the MABR process, the aeration membrane provides a carrier for microbial attachment on the one hand, and supplies oxygen to the attached microorganisms through the membrane cavity on the other hand, achieving nitrification and denitrification at the same time, with an oxygen utilization rate of nearly 100% and extremely low energy consumption, which is very promising in terms of carbon emission reduction in sewage treatment.

[0003] MABR aeration membrane is the core material of the MABR process. It has high oxygen permeability, good bioaffinity, and high mechanical properties. The MABR aeration membranes currently used in the market are mainly divided into three categories: hydrophobic microporous membranes, dense membranes, and composite membranes. The hydrophobic microporous membrane is made of hydrophobic polymer materials. Micropores with a diameter of about 0.01 to 2 μm are distributed on the surface of the membrane. The gas flux is large, but the bubble point is relatively low. During operation, proteins and bacterial debris can easily enter the membrane pores, resulting in reduced gas flux and reduced hydrophobicity, which ultimately affects the oxygen permeability. At the same time, the aeration pressure is limited by the maximum pressure of the microporous membrane during use. The gas in the dense membrane has a high bubble point pressure due to the density of its structure, but due to the large gas mass transfer resistance, the membrane flux is low and the operating energy consumption is high. While solving the problem of low bubble point of the microporous membrane, the composite membrane also retains its large flux characteristics. However, the composite membrane also has disadvantages such as complex preparation process, insufficient bonding between the polymer layer and the base membrane, easy to fall off, and the thickness of the prepared membrane is above 10-100 microns, and low oxygen permeability. It cannot meet the membrane components used in MABR hollow fiber composite membranes and cannot meet the requirements of easy biological attachment and high air permeability. Summary of the invention

[0004] In view of this, the present invention proposes a polyaniline modified microporous aeration membrane and a preparation method thereof, so that the composite membrane can be used in MABR sewage treatment.

[0005] The specific technical solutions are as follows:

[0006] A polyaniline modified microporous aeration membrane adopts a three-layer structure, which comprises a first base fabric support layer, a second microporous membrane, and a third modified coating layer; the first base fabric support layer is a non-woven fabric made of organic polymer material, the second microporous membrane is a microporous membrane made of polymer organic material; the third modified coating layer is a coating modification on the microporous membrane, and is formed by a polyaniline coating after a chemical reaction on the microporous membrane surface after aniline coating.

[0007] Furthermore, the first base fabric support layer and the second microporous membrane are prepared to form a dense membrane;

[0008] Furthermore, the dense membrane is a flat membrane roll, with 0.5-2um membrane pores all over the surface, a porosity greater than 70%, and a thin layer thickness.

[0009] Furthermore, the third modified coating layer is a polyaniline coating formed by immersing the dense film in an aniline solution and then immersing the dense film in an oxidant to react with the aniline.

[0010] Furthermore, the oxidant is ammonium persulfate.

[0011] A method for preparing a polyaniline modified microporous aeration membrane comprises the following steps:

[0012] Prepare solution 1: dissolve aniline in hydrochloric acid solution to a concentration of 0.2-2 mol / L, stir in an ice bath, control the temperature below 10°C, and add a surfactant;

[0013] Prepare solution 2: prepare ammonium persulfate into a 1-4 mol / L solution;

[0014] Soak the dense membrane in solution 1 for 3-5 minutes, squeeze out excess liquid, and then soak it in solution 2 for 1-3 minutes;

[0015] After soaking, the membrane surface temperature is controlled to be less than 10℃ through the cold air channel.

[0016] The preparation is completed after heat drying and rolling.

[0017] Furthermore, the hydrochloric acid solution has a concentration of 1-5 mol / L; the soaking temperature is controlled below 10°C; and the drying is performed by hot air circulation, with the temperature controlled not to exceed 60°C.

[0018] In summary, the present invention has the following beneficial effects:

[0019] 1. The present invention covers a thin layer of high-flux polymer on the surface of the microporous membrane, which solves the problem of low bubble point of the microporous membrane on the one hand, and achieves lower mass transfer resistance and higher oxygen permeability by selecting a coating material with strong oxygen permeability and reducing the coating thickness on the other hand. The polyaniline modified microporous aeration membrane for sewage treatment prepared by the present invention has the characteristics of no bubbles, rich oxygen, and easy biological attachment, while also having good air permeability and economy;

[0020] 2. The main body of the polyaniline modified microporous aeration membrane is porous and super-hydrophobic, with high air permeability and excellent oxygen mass transfer performance. Polyaniline has non-porous high oxygen permeability, which effectively prevents biological cells from entering the membrane pores, and has excellent microbial affinity, which is conducive to the attachment and growth of microorganisms on the membrane surface;

[0021] 3. Both polyaniline and base membrane materials have stable physical and chemical properties. During the formation of microbial membranes and the operation of sewage process systems, they are not easily degraded and aged by microorganisms and have long-term stability.

[0022] 4. The present invention is simple to synthesize and low in cost. Through relevant research and experiments on polyaniline modification, it is proved that the present invention has the advantages of environmental protection, high efficiency and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 , flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0025] A polyaniline modified microporous aeration membrane adopts a three-layer structure, which includes a first base fabric support layer, a second microporous membrane, and a third modified coating layer; the first base fabric support layer is a high molecular organic material such as a polytetrafluoroethylene microporous membrane, a nylon microporous membrane, a polyethersulfone microporous membrane, a polyethylene membrane, etc., and the second microporous membrane is a hydrophobic microporous membrane. The first base fabric support layer and the second microporous membrane are prepared to form a dense membrane; the formation process of the third modified coating layer is: the dense membrane is first soaked in an aniline solution, and then soaked in ammonium persulfate for oxidation to form a polyaniline coating, wherein the aniline solution is an aniline hydrochloric acid solution and a surfactant is added.

[0026] The preferred solutions are as follows:

[0027] Preferably: the first base fabric support layer is a polytetrafluoroethylene microporous membrane, a nylon microporous membrane, a polyethersulfone microporous membrane, or a polyethylene membrane; the dense membrane is a flat membrane roll; the polytetrafluoroethylene membrane, the nylon microporous membrane, the polyethersulfone microporous membrane, or the polyethylene membrane has 0.5-2um membrane pores distributed on its surface, and the porosity is greater than 70%.

[0028] Embodiment 1:

[0029] A method for preparing a polyaniline modified microporous aeration membrane comprises the following steps:

[0030] Step 1: Dissolve aniline in hydrochloric acid solution with a concentration of 0.2-2 mol / L, stir in an ice bath, control the temperature below 10°C, add a surfactant, and pour into sink 1;

[0031] Step 2: Prepare ammonium persulfate into a 1-4 mol / L solution and pour it into water tank 2;

[0032] Step 3: Soak the polytetrafluoroethylene microporous membrane roll in water tank 1 for 3 minutes, squeeze out excess liquid, and then soak it in water tank 2 for 1 minute;

[0033] Step 4: Pass the soaked membrane through the cold air channel to control the membrane surface temperature to less than 10°C;

[0034] Step 5: After heat drying and rolling, the polyaniline modified microporous aeration membrane is obtained.

[0035] Preferably: in Step 1, the hydrochloric acid solution has a concentration of 1-5 mol / L.

[0036] Preferably: in Step 3, the soaking temperature is controlled below 10°C.

[0037] Preferably: in Step 5, the drying is performed by hot air circulation, and the temperature is controlled not to exceed 60°C.

[0038] Embodiment 2:

[0039] The preparation method of polyaniline modified microporous aeration membrane for sewage treatment comprises the following steps:

[0040] Step 1: Dissolve aniline in hydrochloric acid solution with a concentration of 0.2-2 mol / L, stir in an ice bath, control the temperature below 10°C, add a surfactant, and pour into sink 1;

[0041] Step 2: Prepare ammonium persulfate into a 1-4 mol / L solution and pour it into water tank 2;

[0042] Step 3: Soak the polytetrafluoroethylene microporous membrane roll in water tank 1 for 5 minutes, squeeze out the excess liquid, and then soak it in water tank 2 for 1 minute;

[0043] Step 4: Pass the soaked membrane through the cold air channel to control the membrane surface temperature to less than 10°C;

[0044] Step 5: After heat drying and rolling, the polyaniline modified microporous aeration membrane is obtained.

[0045] Embodiment 3:

[0046] The preparation method of polyaniline modified microporous aeration membrane for sewage treatment comprises the following steps:

[0047] Step 1: Dissolve aniline in hydrochloric acid solution with a concentration of 0.2-2 mol / L, stir in an ice bath, control the temperature below 10°C, add a surfactant, and pour into sink 1;

[0048] Step 2: Prepare ammonium persulfate into a 1-4 mol / L solution and pour it into water tank 2;

[0049] Step 3: Soak the polyethylene microporous membrane roll in water tank 1 for 3 minutes, squeeze out excess liquid, and then soak it in water tank 2 for 1 minute;

[0050] Step 4: Pass the soaked membrane through the cold air channel to control the membrane surface temperature to less than 10°C;

[0051] Step 5: After heat drying and rolling, the polyaniline modified microporous aeration membrane is obtained.

[0052] Performance Testing

[0053] According to GB / T 19789-2021 Coulometric Detection Method for Oxygen Permeability of Plastic Films and Sheets for Packaging Materials, the polyaniline modified microporous aeration membranes prepared in Examples 1-3 were tested for oxygen permeability.

[0054] The test results are shown in Table 1.

[0055] Table 1. Performance results of Examples 1-3

[0056] Air permeability / GPU <![CDATA[O2 / N2 separation coefficient]]> Electron microscope surface hole Example 1 6170 24.3 none Example 2 5263 21.2 none Example 3 5338 22.1 none

[0057] As shown in Table 1, the polyaniline modified microporous aeration membrane prepared in Examples 1-3 has super hydrophobic properties and excellent air permeability. After polyaniline modification, no pores were observed under a 3000x electron microscope, and the oxygen content detected by air permeability test was 31%, which is conducive to the growth of microorganisms and effectively prevents biological debris from entering the membrane pores and clogging them.

[0058] Both polyaniline and polytetrafluoroethylene microporous membrane materials have stable physical and chemical properties. During the formation of microbial membranes and the operation of sewage process systems, they are not easily degraded and aged by microorganisms and have long-term stability.

[0059] The polyaniline modified microporous aeration membrane for sewage treatment prepared by the invention has the characteristics of no bubbles, rich oxygen, easy biological attachment, and good air permeability and economy.

[0060] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A polyaniline modified microporous aeration membrane, characterized in that: The invention adopts a three-layer structure, which comprises a first base fabric support layer, a second microporous membrane, and a third modification coating layer; the first base fabric support layer is a non-woven fabric made of organic polymer material, the second microporous membrane is a microporous membrane made of polymer organic material; the third modification coating layer is a coating modification on the microporous membrane, which is formed by coating aniline and then chemically reacting on the surface of the microporous membrane to form a polyaniline coating.

2. The polyaniline modified microporous aeration membrane according to claim 1, characterized in that: The first base fabric support layer and the second microporous membrane layer are prepared to form a dense membrane.

3. A polyaniline modified microporous aeration membrane according to claim 2, characterized in that: The dense membrane is a flat membrane roll with 0.5-2um membrane pores all over the surface and a porosity of more than 70%.

4. The polyaniline modified microporous aeration membrane according to any one of claims 1 to 3, characterized in that: The third modified coating layer is a polyaniline coating formed by immersing the dense film in an aniline solution and then immersing it in an oxidant to react with the aniline.

5. The polyaniline modified microporous aeration membrane according to claim 4, characterized in that: The oxidant is ammonium persulfate.

6. A method for preparing a polyaniline modified microporous aeration membrane, characterized in that: The following steps are included: Prepare solution 1: dissolve aniline in hydrochloric acid solution to a concentration of 0.2-2 mol / L, stir in an ice bath, control the temperature below 10°C, and add a surfactant; Prepare solution 2: prepare ammonium persulfate into a 1-4 mol / L solution; Soak the dense membrane in solution 1 for 3-5 minutes, squeeze out excess liquid, and then soak it in solution 2 for 1-3 minutes; After soaking, the membrane surface temperature is controlled to be less than 10℃ through the cold air channel; The preparation is completed after heat drying and rolling.

7. The method for preparing a polyaniline modified microporous aeration membrane according to claim 6, characterized in that: The hydrochloric acid solution has a concentration of 1-5 mol / L; the soaking temperature is controlled below 10°C; Drying is hot air circulation, and the temperature is controlled not to exceed 60℃.

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