CN106563361B - Application of hollow fiber braided tube, hollow fiber desalting membrane and preparation method thereof - Google Patents
Application of hollow fiber braided tube, hollow fiber desalting membrane and preparation method thereof Download PDFInfo
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- CN106563361B CN106563361B CN201610908855.3A CN201610908855A CN106563361B CN 106563361 B CN106563361 B CN 106563361B CN 201610908855 A CN201610908855 A CN 201610908855A CN 106563361 B CN106563361 B CN 106563361B
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Abstract
The invention provides an application of a hollow fiber braided tube, a hollow fiber desalting membrane and a preparation method thereof, in particular to a hollow fiber braided tube enhanced desalting membrane obtained by adopting the hollow fiber braided tube, wherein the preparation method comprises the following steps: (1) the hollow fiber braided tube is taken as a base lining, high-temperature singeing treatment is carried out, the surface of the braided tube is removed of the disordered fiber, and then the surface of the braided tube is coated with a polymer to prepare a hollow fiber ultrafiltration membrane; (2) forming an ultrathin desalting layer (an interfacial polymerization functional layer) on the surface of the ultrafiltration membrane by adopting an interfacial polymerization method after the ultrafiltration membrane passes through polyamine aqueous solution and polyacylchloride organic solution to obtain a hollow fiber desalting membrane; the obtained hollow fiber desalination membrane is a low-defect membrane, can effectively improve the utilization rate of the membrane, reduces extra economic cost caused by membrane defects, has a certain positive effect on membrane preparation and popularization and application, and ensures that membrane filaments are influenced by high operating pressure to generate self-compaction in the use process and cannot generate defects in the operation process.
Description
Technical Field
The invention relates to the technical field of membrane separation, in particular to an application of a hollow fiber braided tube, a hollow fiber desalting membrane and a preparation method thereof.
Background
The membrane separation technology is a new high-efficiency separation technology, which has been widely applied in the fields of chemical industry, environmental protection, electronics, light industry, textile, energy engineering and the like, and foreign experts even refer to the development of the membrane separation technology as the third industrial revolution.
With the increasing severity of water resource problems, the fields of seawater desalination and wastewater treatment are increasingly prominent, and therefore, the application of desalination membranes is also increasingly wide. The membrane technology is separation and purification carried out at an ion level, so that the ion level separation is realized, and besides the distribution range of the membrane pore size is narrow, defects, namely pores, cannot exist on the membrane surface. To date, the defects at the surface or deep layer of the film still limit the large-scale use of the film, and although the number of defects is small, the effect is quite serious: the existence of membrane defects not only affects the separation and purification effect of the membrane, but also reduces the filtration performance of the membrane, the service life of the membrane and the desalination efficiency, so that high attention must be paid to the membrane defect phenomenon.
The desalination membrane must operate under higher operating pressure in order to overcome osmotic pressure, the conventional hollow fiber membrane is not suitable for preparing the desalination membrane due to the problem of poor pressure resistance, the conventional desalination membrane is mainly in a roll type form at present, and the preparation method comprises the following steps: coating an ultrafiltration membrane forming system on the surface of the non-woven fabric by taking the non-woven fabric as a substrate to prepare a roll type ultrafiltration membrane, and preparing a desalination function layer on the surface of the obtained roll type ultrafiltration membrane through interfacial polymerization to prepare the roll type desalination membrane.
The non-woven fabric is prepared by spraying directional or random fibers, a large number of non-directional fibers exist on the surface of the non-woven fabric, and due to the existence of the non-directional fibers, the phenomenon that an ultrafiltration film forming system is unevenly coated or even uncoated is easily formed around the non-directional fibers due to the surface tension of the non-directional fibers and other reasons in the process of coating the ultrafiltration film forming system, and defects are formed in the process of preparing a subsequent interface functional layer; in addition, because the roll-type desalination membrane needs to be paved with a separation net supporting layer to prepare a roll-type membrane component, the separation net in the component is easy to sink into the desalination membrane under the influence of high operation pressure, so that the defect of the desalination membrane is formed, and the whole desalination rate of the desalination membrane is reduced
Disclosure of Invention
The technical problem to be solved by the invention is to provide the application of the hollow fiber braided tube.
The invention provides a preparation method of a hollow fiber desalination membrane by utilizing the purpose of a hollow fiber braided tube.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the hollow fiber braided tube is used for preparing a hollow fiber desalting membrane, and the hollow fiber braided tube needs to be subjected to high-temperature singeing treatment to remove the surface disorder fibers of the braided tube.
Preferably, the hollow fiber braided tube is made of polyethylene terephthalate (PET), Polyacrylonitrile (PAN) or Polytetrafluoroethylene (PTFE).
The hollow fiber desalting membrane is a braided tube enhanced hollow fiber desalting membrane formed by taking the hollow fiber braided tube with the surface disorder fibers removed as an enhancement body and compounding an ultrafiltration functional layer and a desalting functional layer.
A preparation method of a hollow fiber desalination membrane comprises the following specific steps:
(1) the hollow fiber braided tube is taken as a base lining, high-temperature singeing treatment is carried out, the surface of the braided tube is removed of the disordered fiber, and then the surface of the braided tube is coated with a polymer to prepare a hollow fiber ultrafiltration membrane;
(2) and (3) forming an ultrathin desalting layer (an interfacial polymerization functional layer) on the surface of the ultrafiltration membrane by adopting an interfacial polymerization method after the ultrafiltration membrane passes through polyamine aqueous solution and polyacyl chloride organic solution to obtain the hollow fiber desalting membrane.
Preferably, in the method for preparing the hollow fiber desalination membrane, the material of the braided tube is polyethylene terephthalate (PET), Polyacrylonitrile (PAN) or Polytetrafluoroethylene (PTFE).
Preferably, in the preparation method of the hollow fiber desalination membrane, the polymer is polyvinylidene fluoride, polyvinyl chloride, polyether sulfone or polysulfone.
Preferably, in the preparation method of the hollow fiber desalination membrane, the interfacial polymerization method in the step (2) is to immerse a single surface of a treated hollow fiber ultrafiltration membrane as a base membrane into polyamine aqueous solution for sufficient contact, drain the membrane, perform interfacial polymerization with acyl chloride organic solution, perform heat treatment, and wash away residual reactants with deionized water.
Preferably, in the preparation method of the hollow fiber desalination membrane, the organic solution of polyacyl chloride in step (2) is an n-hexane solution of trimesoyl chloride.
Preferably, in the preparation method of the hollow fiber desalination membrane, the mass concentration of the n-hexane solution of trimesoyl chloride is 0.05-3%.
Preferably, in the method for preparing the hollow fiber desalination membrane, the polyamine aqueous solution in the step (2) is a piperazine aqueous solution, a diethylenetriamine aqueous solution or a m-phenylenediamine aqueous solution.
Preferably, in the method for preparing the hollow fiber desalination membrane, the mass concentration of the piperazine aqueous solution, the diethylenetriamine aqueous solution or the m-phenylenediamine aqueous solution is 0.1-5%.
The invention has the beneficial effects that:
the hollow fiber braided tube is used as a specific base lining for preparing the hollow fiber desalting membrane, the structure is regular, fuzz on the surface of the hollow fiber braided tube can be effectively removed after singeing treatment, the hollow fiber braided tube is more smooth, a polymer microporous base membrane is coated on the hollow fiber braided tube to serve as a supporting layer, and a compact ultrathin desalting layer is compounded on the polymer microporous base membrane by utilizing an interfacial polymerization method, so that the preparation purpose can be realized.
According to the preparation method of the hollow fiber desalination membrane, the braided tube subjected to singeing treatment is used, the surface is more regular and smooth, the membrane defects can be reduced to a certain extent, the base membrane is more uniformly coated on the surface of the braided tube and is organically combined with the braided tube, and the base membrane has stronger binding force, so that the membrane layer and the braided tube are organically fused together, the mechanical property is greatly improved, and the defects formed in the subsequent membrane preparation process are fewer.
The formation of the low-defect film can effectively improve the utilization rate of the film, reduce the additional economic cost caused by the film defect, and has certain positive effects on film preparation and popularization and application.
Because the hollow fiber desalination membrane is fibrous, the membrane filaments are influenced by high operation pressure to generate self-compaction in the use process, and the defect can not be generated in the operation process.
Drawings
FIG. 1 is a comparison of the matrix lining of the roll desalination membrane and the hollow fiber desalination membrane.
FIG. 2 is a schematic view of the pressure-bearing of the internal membranes of the roll-type desalination membrane module and the hollow fiber desalination membrane module.
Detailed Description
The technical solution of the present invention is further described with reference to the following specific examples.
Example 1
Selecting a braided tube (polyethylene terephthalate material) treated by a singeing process, coating a polyvinylidene fluoride ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into m-phenylenediamine aqueous solution (with the mass concentration of 2.5%) to be fully contacted, draining, carrying out interfacial polymerization reaction with trimesoyl chloride/n-hexane solution (with the mass concentration of 1.5%), finally carrying out heat treatment, and washing residual reactants by deionized water to obtain the low-defect hollow fiber desalting membrane. The desalination rate of the membrane is tested after the membrane is treated, and the result shows that when the braided tube treated by the singeing process is used as the base lining, the desalination rate reaches 99 percent.
Comparative example 1
Selecting a conventional base non-woven fabric to coat a polyvinylidene fluoride ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into a m-phenylenediamine aqueous solution (mass concentration is 2.5 percent) to be in full contact, draining, carrying out interfacial polymerization reaction with a trimesoyl chloride/n-hexane solution (mass concentration is 1.5 percent), finally carrying out heat treatment, and washing out residual reactants by using deionized water to obtain the roll-type desalting membrane. The desalination rate of the membrane after being treated is tested, and the result shows that the desalination rate is 96% when the non-woven fabric is used as the base lining.
Comparative example 2
Selecting a braided tube which is not subjected to a singeing process, coating a polyvinylidene fluoride ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into m-phenylenediamine aqueous solution (with the mass concentration of 2.5%) to be in full contact, draining, carrying out interfacial polymerization reaction with trimesoyl chloride/n-hexane solution (with the mass concentration of 1.5%), finally carrying out heat treatment, and washing out residual reactants by using deionized water to obtain the hollow fiber desalting membrane. The desalination rate of the membrane after treatment was tested, and the results showed that the desalination rate was 97% when the unfinished braided tube was selected as the substrate.
The other conditions of the above 3 examples are exactly the same.
It can be seen from the above examples and comparative examples that the selection of the braided tube subjected to the singeing process (i.e., the treatment method of removing fuzz formed on the surface of the braided tube due to the un-entangled fibers and the protruding fibers) can effectively improve the salt rejection of the membrane filaments and reduce the defects of the membrane.
In conclusion, the key of the preparation method of the low-defect hollow fiber desalination membrane lies in the selection of the substrate. As can be seen from fig. 1, the commonly used nonwoven fabric has a disordered structure, which has no advantages as a base layer, and the disordered structure makes the surface rough and uneven, so that many concave-convex points appear during the coating step, and further holes, i.e. film defects, are formed. The invention provides a fiber braided tube with a regular structure as a base lining, aiming at the defects of the conventional non-woven fabric base lining, the preparation process of the braided tube ensures that the whole structure of the braided tube is regular, and the braided tube used as the base lining is also treated by a singeing process, so that the surface of the braided tube is smoother and smoother, concave and convex points are relatively less, and the defects formed in coating and subsequent process preparation are less. After the selection of the substrate, a specific polymer base membrane is coated, the upper surface of the base membrane is immersed in the aqueous phase solution for a certain time, redundant aqueous solution is removed, the membrane is immersed in the organic phase for reaction for a certain time, the membrane is dried in the air, and then the hollow fiber desalination membrane is obtained through heat treatment and deionized water rinsing.
The existence of membrane defect not only can influence the separation purification effect of membrane, still can make membrane filtration performance descend, and membrane life reduces, and desalination efficiency reduces, and the utilization of weaving the pipe can effectively reduce membrane defect, and the formation of this kind of low defect membrane can improve the utilization ratio of membrane, reduces the extra economic cost who leads to because of membrane defect, all has certain positive effect to membrane preparation and popularization membrane application.
Example 2
Selecting a braided tube (polytetrafluoroethylene) treated by a singeing process, coating a polyether sulfone ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into a piperazine aqueous solution (with the mass concentration of 5%) for full contact, draining, carrying out interfacial polymerization reaction with a trimesoyl chloride/n-hexane solution (with the mass concentration of 3%), finally carrying out heat treatment, and washing out residual reactants by using deionized water to obtain the low-defect hollow fiber desalting membrane. The salt rejection of the membrane after treatment was tested to be 98%. The hollow fiber desalination membrane is used for preparing a hollow fiber desalination membrane component, the component is continuously filtered for 10 hours under 10MPa for 2g/L MgSO4 solution, and then the desalination rate of the component is tested, and the desalination rate reaches 96%.
Comparative example 1
Selecting a conventional base layer non-woven fabric to coat a polyether sulfone ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into a piperazine aqueous solution (with the mass concentration of 5%) to be in full contact with the base membrane, draining the base membrane, performing interfacial polymerization reaction with a trimesoyl chloride/n-hexane solution (with the mass concentration of 3%), finally performing heat treatment, and washing out residual reactants by using deionized water to obtain the roll-type desalting membrane. The salt rejection was tested to be 95% after the membrane was treated. The roll-type desalination membrane is used for preparing a roll-type desalination membrane component, the component is continuously filtered for 10 hours at 10MPa for 2g/L MgSO4 solution, and then the desalination rate of the component is tested, and the desalination rate reaches 89%.
It can be seen from the above examples and comparative examples that the hollow fiber desalination membrane prepared from the braided tube treated by the singeing process has improved desalination rate, and the performance stability of the component continuously operating under 10MPa high pressure after the hollow fiber desalination membrane component is prepared is also improved compared with that of a roll-type desalination membrane component.
As can be seen from fig. 2, the separation net is laid in the rolled membrane module, and is influenced by liquid pressure in the operation process, the separation net is extruded on the surface of the rolled desalination membrane, and under long-time operation, the functional layer on the surface of the membrane is inevitably damaged by extrusion of the separation net, so that the desalination performance of the module is influenced. The section of the hollow fiber desalination membrane prepared by the invention is in a ring shape, and the membrane is subjected to liquid pressure pointing to the circle center from the periphery of the membrane in the operation process, so that a compaction effect is formed on a functional layer on the surface of the membrane in the filtration process, the functional layer is more compact, and the hollow fiber membrane desalination assembly can continuously keep higher desalination capacity in long-time operation.
Example 3
Selecting a braided tube (polyacrylonitrile) treated by a singeing process to coat a polyvinyl chloride ultrafiltration membrane as a base membrane, immersing one side of the treated base membrane into a diethylenetriamine aqueous solution (with the mass concentration of 0.1%) to be in full contact, draining, carrying out interfacial polymerization reaction with a trimesoyl chloride/n-hexane solution (with the mass concentration of 0.05%), finally carrying out heat treatment, and washing out residual reactants by using deionized water to obtain the low-defect hollow fiber desalting membrane. The desalination rate of the membrane is tested after the membrane is treated, and the result shows that when the braided tube treated by the singeing process is used as the base lining, the desalination rate reaches 98 percent.
The use of the hollow fiber braided tube and the hollow fiber desalination membrane and the method for preparing the same, which have been described in detail above with reference to the examples, are illustrative and not restrictive, and several examples can be cited within the limits thereof, and thus variations and modifications thereof without departing from the general concept of the present invention should fall within the scope of the present invention.
Claims (8)
1. A preparation method of a hollow fiber desalination membrane is characterized by comprising the following steps: the method comprises the following specific steps:
(1) taking a hollow fiber braided tube as a base lining, and removing disordered fibers on the surface of the hollow fiber braided tube through high-temperature singeing treatment; removing the surface disordered fibers of the braided tube, and coating a polymer on the surface to prepare a hollow fiber ultrafiltration membrane;
(2) and (3) forming an ultrathin desalting layer, namely an interfacial polymerization functional layer, on the surface of the ultrafiltration membrane by adopting an interfacial polymerization method after the ultrafiltration membrane passes through polyamine aqueous solution and polyacyl chloride organic solution to obtain the hollow fiber desalting membrane.
2. The method for preparing a hollow fiber desalination membrane according to claim 1, characterized in that: the material of the braided tube is polyethylene terephthalate, polyacrylonitrile or polytetrafluoroethylene.
3. The method for preparing a hollow fiber desalination membrane according to claim 1, characterized in that: the polymer is polyvinylidene fluoride, polyvinyl chloride, polyether sulfone or polysulfone.
4. The method for preparing a hollow fiber desalination membrane according to claim 1, characterized in that: the interfacial polymerization method in the step (2) is to immerse a treated hollow fiber ultrafiltration membrane as a base membrane on one side of the hollow fiber ultrafiltration membrane into polyamine aqueous solution for full contact, perform interfacial polymerization reaction with polyacyl chloride organic solution after draining, perform heat treatment, and wash away residual reactants with deionized water.
5. The method for preparing a hollow fiber desalination membrane according to claim 1, characterized in that: and (3) the organic solution of the polyacyl chloride in the step (2) is a normal hexane solution of trimesoyl chloride.
6. The method for preparing a hollow fiber desalination membrane according to claim 5, characterized in that: the mass concentration of the n-hexane solution of trimesoyl chloride is 0.05-3%.
7. The method for preparing a hollow fiber desalination membrane according to claim 1, characterized in that: and (3) the polyamine aqueous solution in the step (2) is a piperazine aqueous solution, a diethylenetriamine aqueous solution or a m-phenylenediamine aqueous solution.
8. The method for preparing a hollow fiber desalination membrane according to claim 7, characterized in that: the mass concentration of the piperazine water solution, the diethylenetriamine water solution or the m-phenylenediamine water solution is 0.1-5%.
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|---|---|---|---|---|
| CN102698614A (en) * | 2012-06-16 | 2012-10-03 | 浙江大学 | Tubular nanofiltration membrane with multi-layer structure and preparation method thereof |
| CN102921318A (en) * | 2012-11-21 | 2013-02-13 | 海南立昇净水科技实业有限公司 | External-pressure type charged hollow fiber nano-filtration membrane and preparation method therefor |
| CN104117289A (en) * | 2014-07-29 | 2014-10-29 | 枫科(北京)膜技术有限公司 | Reinforced composite supported hollow fiber membrane and preparation method thereof |
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| TWI398353B (en) * | 2009-03-02 | 2013-06-11 | Ind Tech Res Inst | Nano-fiber material and salt-rejecting filtration material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102698614A (en) * | 2012-06-16 | 2012-10-03 | 浙江大学 | Tubular nanofiltration membrane with multi-layer structure and preparation method thereof |
| CN102921318A (en) * | 2012-11-21 | 2013-02-13 | 海南立昇净水科技实业有限公司 | External-pressure type charged hollow fiber nano-filtration membrane and preparation method therefor |
| CN104117289A (en) * | 2014-07-29 | 2014-10-29 | 枫科(北京)膜技术有限公司 | Reinforced composite supported hollow fiber membrane and preparation method thereof |
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