Oily tubular membrane and preparation method thereof

Abstract

The present invention discloses an oily tubular membrane, comprising a composite membrane with a tubular structure, wherein the composite membrane comprises a support layer, a base membrane layer and a protective layer from the outside to the inside, wherein the support layer is a non-woven fabric layer or a PET layer, and the base membrane layer is a modified polyethersulfone ultrafiltration membrane layer. The liquid membrane-making solution of the modified polyethersulfone ultrafiltration membrane layer is mainly prepared by reacting the following materials in a reaction kettle: 10 wt %~30 wt % Polyethersulfone, 0.1 wt %~10 wt % lipophilic nano-silica, 50 wt %~80 wt % dimethylacetamide, 1 wt %~10 wt % methacrylic acid, 0.5 wt %~10 wt % acrylonitrile, 0.5 wt %~10 wt % azobisisobutyronitrile and 0.5 wt %~10 wt % polyethylene glycol, and the protective layer is white oil. The invention also discloses a method for preparing an oily tubular membrane, and the obtained oily tubular membrane can be used for separating waste edible oil, with high separation efficiency and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to an oily tubular membrane and a preparation method thereof. Background Art

[0002] Waste cooking oil has a relatively high content of organic matter and has a certain recycling value. Its effective recycling method is concentrated in the preparation of biodiesel and other uses. According to calculations, 1 ton of waste cooking oil can produce nearly 1 ton of biodiesel after adding relevant additives, which is widely used in various industrial projects; traditional waste oil recovery methods include biodegradation, pyrolysis, centrifugation and precipitation. These methods usually have the characteristics of low separation efficiency, low recovery rate, high maintenance cost, inability to prepare in large quantities, and possible secondary pollution. The economic benefits are not high. At present, waste cooking oil is still a kind of waste that is difficult to effectively utilize in our daily life.

[0003] Membrane separation is a contemporary new high-efficiency separation technology that is widely used in environmental protection and sewage treatment, seawater and brackish water desalination, pure water and ultrapure water preparation, biological separation and medical instruments, and is expected to become a new way to recycle waste cooking oil. Summary of the invention

[0004] The object of the present invention is to provide an oily tubular membrane and a preparation method thereof. The obtained oily tubular membrane can be used for separation of waste edible oil, has high separation efficiency and low cost.

[0005] In order to achieve the above object, the solution of the present invention is:

[0006] An oily tubular membrane comprises a composite membrane with a tubular structure, wherein the composite membrane comprises a support layer, a base membrane layer and a protective layer from the outside to the inside, wherein the support layer is a non-woven fabric layer or a PET layer, and the base membrane layer is a modified polyethersulfone ultrafiltration membrane layer. The liquid membrane-making solution of the modified polyethersulfone ultrafiltration membrane layer is mainly prepared by reacting the following materials in a weight ratio into a reactor: 10 wt %~30 wt % Polyethersulfone, 0.1 wt %~10 wt % lipophilic nano-silica, 50 wt %~80 wt % dimethylacetamide, 1 wt %~10 wt % methacrylic acid, 0.5 wt %~10 wt % acrylonitrile, 0.5 wt %~10 wt % azobisisobutyronitrile and 0.5 wt %~10 wt % polyethylene glycol, and the protective layer is white oil.

[0007] A method for preparing an oily tubular membrane comprises the following steps:

[0008] Step 1: Prepare a liquid film-forming solution for forming a base film layer:

[0009] First 10 wt %~30 wt % Polyethersulfone, 0.1 wt %~10 wt % lipophilic nano-silica, 50 wt %~80 wt % dimethylacetamide, 1 wt %~10 wt % methacrylic acid, 0.5 wt %~10 wt % acrylonitrile, 0.5 wt %~10 wt % azobisisobutyronitrile and 0.5 wt %~10 wt % polyethylene glycol is mixed in a reaction kettle, and polymerization reaction is carried out at 50-100° C. After the reaction is completed, excess polyethylene glycol is removed by extraction to obtain the liquid film-forming solution;

[0010] Step 2: preparing a tubular modified polyethersulfone ultrafiltration membrane consisting of a support layer and a base membrane layer:

[0011] Then, the sheet-like support layer is rolled into a tube by a tube rolling machine, and then welded into a tubular support layer by an ultrasonic welding machine, and at the same time, the liquid membrane-making liquid prepared in step 1 is simultaneously coated with a base film on the inner surface of the tubular support layer, and then enters a gel bath tank for curing, so as to obtain the tubular modified polyethersulfone ultrafiltration membrane;

[0012] Step 3: Prepare the protective layer:

[0013] Finally, the tubular modified polyethersulfone ultrafiltration membrane prepared in step 2 is immersed in white oil for reaction. After reacting for 5 to 15 hours, it is taken out and dried to obtain the oily tubular membrane having a support layer, a base membrane layer and a protective layer composited from the outside to the inside.

[0014] In step 1, the extraction solvent used in the extraction is deionized water or ethanol.

[0015] The liquid film-making liquid obtained in step 1 is extruded by a wire extruder and then enters the film device in the tube winding machine in step 2, so that the base film coating and the tube winding in step 2 are carried out synchronously.

[0016] The tubular modified polyethersulfone ultrafiltration membrane obtained in step 2 needs to be rinsed and soaked in deionized water before entering the white oil.

[0017] After adopting the above technical scheme, the oily tubular membrane of the present invention uses polyethersulfone as a base membrane, uses lipophilic nano-silica to modify the lipophilicity of polyethersulfone, and then uses dimethylacetamide as a solvent, methacrylic acid as a functional monomer, acrylonitrile as a cross-linking agent, and azobisisobutyronitrile as an initiator to form a polymerization initiation reaction system, thereby functionally modifying the polyethersulfone to form an oily tubular membrane capable of filtering small molecules of oils and fats with a target molecular weight of 3000-6000 D, which is not easy to be blocked, has high separation efficiency, and has low cost. It has the advantages of high temperature resistance, organic solvent resistance, strong acid and alkali resistance, and large oil flux, and can be applied to the separation, clarification and purification of various oils and fats, and solves the technical problem that conventional varieties cannot effectively resist solvents and high temperatures. DETAILED DESCRIPTION

[0018] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0019] Example 1

[0020] An oily tubular membrane comprises a composite membrane with a tubular structure, wherein the composite membrane comprises a support layer, a base membrane layer and a protective layer from the outside to the inside, wherein the support layer is a non-woven fabric layer, the base membrane layer is a modified polyethersulfone ultrafiltration membrane layer, and the liquid membrane-making solution of the modified polyethersulfone ultrafiltration membrane layer is mainly prepared by reacting the following materials in a weight ratio into a reactor: 10 wt % Polyethersulfone, 0.1 wt % lipophilic nano-silica, 80 wt % dimethylacetamide, 1 wt % methacrylic acid, 0.5 wt % acrylonitrile, 0.5 wt % azobisisobutyronitrile and 7.9 wt % polyethylene glycol, the protective layer is white oil.

[0021] A method for preparing an oily tubular membrane comprises the following steps:

[0022] Step 1: Prepare a liquid film-forming solution for forming a base film layer:

[0023] First 10 wt % Polyethersulfone, 0.1 wt % lipophilic nano-silica, 80 wt % dimethylacetamide, 1 wt % methacrylic acid, 0.5 wt % acrylonitrile, 0.5 wt % azobisisobutyronitrile and 7.9 wt % polyethylene glycol is mixed in a reactor and polymerized at 80°C. After the reaction is completed, the excess polyethylene glycol is extracted with deionized water to obtain a liquid film-making liquid. The liquid film-making liquid is extruded by a wire extruder and then enters the film device in the tube winding machine, so that the subsequent base film coating and tube winding can be carried out simultaneously.

[0024] Step 2: preparing a tubular modified polyethersulfone ultrafiltration membrane consisting of a support layer and a base membrane layer:

[0025] The sheet-like nonwoven fabric is then rolled into a tube by a tube rolling machine, and then welded into a tubular support layer by an ultrasonic welding machine. At the same time, the liquid membrane-making liquid prepared in step 1 is simultaneously coated with a base film on the inner surface of the tubular support layer, and then enters a gel bath tank for curing to obtain a tubular modified polyethersulfone ultrafiltration membrane, which is then rinsed and soaked in deionized water to clean the solvent dimethylacetamide and the porogen polyethylene glycol;

[0026] Step 3: Prepare the protective layer:

[0027] Finally, the tubular modified polyethersulfone ultrafiltration membrane prepared in step 2 is immersed in white oil for reaction. After reacting for 5 hours, it is taken out and dried to obtain an oily tubular membrane having a support layer, a base membrane layer and a protective layer from the outside to the inside.

[0028] Example 2

[0029] An oily tubular membrane comprises a composite membrane with a tubular structure, wherein the composite membrane comprises a support layer, a base membrane layer and a protective layer from the outside to the inside, wherein the support layer is a PET layer, the base membrane layer is a modified polyethersulfone ultrafiltration membrane layer, and the liquid membrane-making liquid of the modified polyethersulfone ultrafiltration membrane layer is mainly prepared by reacting the following materials in a reaction kettle: 25 wt % polyethersulfone, 8 wt % lipophilic nano-silica, 50 wt % dimethylacetamide, 5 wt % methacrylic acid, 5 wt % acrylonitrile, 3 wt % azobisisobutyronitrile and 4 wt % polyethylene glycol, the protective layer is white oil.

[0030] A method for preparing an oily tubular membrane comprises the following steps:

[0031] Step 1: Prepare a liquid film-forming solution for forming a base film layer:

[0032] First 25 wt % polyethersulfone, 8 wt % lipophilic nano-silica, 50 wt % dimethylacetamide, 5 wt % methacrylic acid, 5 wt % acrylonitrile, 3 wt % azobisisobutyronitrile and 4 wt % polyethylene glycol is mixed in a reactor and polymerized at 100 °C. After the reaction is completed, excess polyethylene glycol is removed by ethanol extraction to obtain a liquid film-making liquid. The liquid film-making liquid is extruded by a wire extruder and then enters the film device in the tube winding machine, so that the subsequent base film coating and tube winding can be carried out simultaneously.

[0033] Step 2: preparing a tubular modified polyethersulfone ultrafiltration membrane consisting of a support layer and a base membrane layer:

[0034] The sheet-like PET is then rolled into a tube by a tube rolling machine, and then welded into a tubular support layer by an ultrasonic welding machine. At the same time, the liquid film-making liquid prepared in step 1 is simultaneously coated with a base film on the inner surface of the tubular support layer, and then enters a gel bath tank for curing to obtain a tubular modified polyethersulfone ultrafiltration membrane, and then rinsed and soaked in deionized water to clean the solvent dimethylacetamide and the porogen polyethylene glycol;

[0035] Step 3: Prepare the protective layer:

[0036] Finally, the tubular modified polyethersulfone ultrafiltration membrane prepared in step 2 is immersed in white oil for reaction. After reacting for 15 hours, it is taken out and dried to obtain an oily tubular membrane having a support layer, a base membrane layer and a protective layer from the outside to the inside.

[0037] Application Example 1

[0038] The oily tubular membrane glue prepared in Example 1 was injected into the tubular membrane module housing to form an oily membrane module, and then the oily membrane module was assembled into a set of membrane equipment with a booster pump, a rack, a pressure gauge, a pipeline flow meter, and an electronic control system, and equipped with a raw material barrel and a finished product barrel to form a membrane system. The waste soybean oil fried in catering was used as a raw material and filtered through this membrane system. The turbidity of the waste soybean oil before filtration was 320 NTU, aflatoxin was 815 ug / kg, the transparency was poor, the peroxide value was 98 mml / kg, and the chromaticity was dark black. The recovered oil obtained after filtration had a turbidity of 0.1 NTU, aflatoxin was 18 ug / kg, the transparency was clear, the peroxide value was 15 mml / kg, and the chromaticity was light yellow.

[0039] It shows that the turbidity removal rate of the oil after filtration through the oily tubular membrane is as high as 99%, the transparency also reaches 99%, and the chromaticity removal rate is about 90%.

[0040] Application Example 2

[0041] The oily tubular membrane glue prepared in Example 2 was injected into the tubular membrane module housing to form an oily membrane module, and then the oily membrane module was assembled into a set of membrane equipment with a booster pump, a rack, a pressure gauge, a pipeline flow meter, and an electronic control system, and equipped with a raw material barrel and a finished product barrel to form a set of membrane systems. Peanut oil crude oil was used as a raw material and filtered through this membrane system. The turbidity of the peanut oil crude oil before filtration was 258 NTU, aflatoxin was 789 ug / kg, the transparency was poor, the peroxide value was 56 mml / kg, and the chromaticity was dark gray. The peanut oil obtained after filtration had a turbidity of 0.23 NTU, aflatoxin was 8 ug / kg, the transparency was clear, the peroxide value was 5 mml / kg, and the chromaticity was light yellow.

[0042] It shows that the turbidity removal rate of the oil after filtration through the oily tubular membrane is as high as 99%, the transparency also reaches 90%, and the chromaticity removal rate is about 90%.

[0043] The above embodiments do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. An oily tubular membrane, comprising a composite membrane in a tubular structure, characterized in that: The composite membrane includes a support layer, a base membrane layer and a protective layer from the outside to the inside, wherein the support layer is a non-woven fabric layer or a PET layer, the base membrane layer is a modified polyethersulfone ultrafiltration membrane layer, and the liquid membrane-making solution of the modified polyethersulfone ultrafiltration membrane layer is mainly prepared by reacting the following materials in a reaction kettle: 10 wt %~30 wt % Polyethersulfone, 0.1 wt %~10 wt % lipophilic nano-silica, 50 wt %~80 wt % dimethylacetamide, 1 wt %~10 wt % methacrylic acid, 0.5 wt %~10 wt % acrylonitrile, 0.5 wt %~10 wt % azobisisobutyronitrile and 0.5 wt %~10 wt % polyethylene glycol, the protective layer is white oil; The method for preparing the oily tubular membrane comprises the following steps: Step 1: Prepare a liquid film-forming solution for forming a base film layer: First 10 wt %~30 wt % Polyethersulfone, 0.1 wt %~10 wt % lipophilic nano-silica, 50 wt %~80 wt % dimethylacetamide, 1 wt %~10 wt % methacrylic acid, 0.5 wt %~10 wt % acrylonitrile, 0.5 wt %~10 wt % azobisisobutyronitrile and 0.5 wt %~10 wt % polyethylene glycol is mixed in a reaction kettle, and polymerization reaction is carried out at 50-100° C. After the reaction is completed, excess polyethylene glycol is removed by extraction to obtain the liquid film-forming solution; Step 2: preparing a tubular modified polyethersulfone ultrafiltration membrane consisting of a support layer and a base membrane layer: Then, the sheet-like support layer is rolled into a tube by a tube rolling machine, and then welded into a tubular support layer by an ultrasonic welding machine, and at the same time, the liquid membrane-making liquid prepared in step 1 is simultaneously coated with a base film on the inner surface of the tubular support layer, and then enters a gel bath tank for curing, so as to obtain the tubular modified polyethersulfone ultrafiltration membrane; Step 3: Prepare the protective layer: Finally, the tubular modified polyethersulfone ultrafiltration membrane prepared in step 2 is immersed in white oil for reaction. After reacting for 5 to 15 hours, it is taken out and dried to obtain the oily tubular membrane having a support layer, a base membrane layer and a protective layer composited from the outside to the inside.

2. The oily tubular membrane according to claim 1, characterized in that: In step 1, the extraction solvent used in the extraction is deionized water or ethanol.

3. The oily tubular membrane according to claim 1, characterized in that: The liquid film-making liquid obtained in step 1 is extruded by a wire extruder and then enters the film device in the tube winding machine in step 2, so that the base film coating and the tube winding in step 2 are carried out synchronously.

4. The oily tubular membrane according to claim 1, characterized in that: The tubular modified polyethersulfone ultrafiltration membrane obtained in step 2 needs to be rinsed and soaked in deionized water before entering the white oil.