CN117225190A - Nonwoven fabric supporting material for nanofiltration membrane and preparation method and application thereof - Google Patents
Nonwoven fabric supporting material for nanofiltration membrane and preparation method and application thereof Download PDFInfo
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- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 239000000835 fiber Substances 0.000 claims abstract description 126
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- 238000004381 surface treatment Methods 0.000 claims abstract description 38
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000002156 mixing Methods 0.000 claims abstract description 26
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- 229920000728 polyester Polymers 0.000 claims abstract description 20
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- 238000006116 polymerization reaction Methods 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- 238000002844 melting Methods 0.000 claims description 6
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- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
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- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 2
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Abstract
The invention provides a non-woven fabric supporting material for a nanofiltration membrane, and a preparation method and application thereof. The invention obtains the tencel fiber with preset beating degree by preprocessing the tencel fiber; dispersing the raw materials into first slurry, mixing the first slurry with second slurry containing polyester fibers and bonding hot-melt fibers according to a preset proportion, pulping, wet forming, drying, surface treatment and hot rolling and calendaring to obtain the non-woven fabric support material for the nanofiltration membrane. Through the mode, the non-woven fabric support material obtained by the invention has the advantages of uniform surface, good hydrophilicity and excellent mechanical property, and can improve the interception effect of the nanofiltration membrane as much as possible while improving the water flux when being applied to the preparation of the nanofiltration membrane, thereby having higher practical application value.
Description
Technical Field
The invention relates to the technical field of nanofiltration membranes, in particular to a nonwoven fabric supporting material for nanofiltration membranes, and a preparation method and application thereof.
Background
Nanofiltration is a novel membrane separation technology developed in recent years. The interception rate of the nanofiltration membrane on monovalent ions is far lower than that of divalent ions, and the nanofiltration membrane has a good separation effect on organic pollutants, and is widely applied to the fields of high-quality drinking water treatment, sewage recycling, valuable material separation and the like due to the unique separation characteristic of the nanofiltration membrane, so that the nanofiltration membrane has a wide market demand. In practical application of nanofiltration membranes, the flux and the retention rate are important points of attention, and the flux of the nanofiltration membranes needs to be further improved along with the gradual increase of the retention rate.
Nanofiltration membranes typically comprise a support layer and a separation layer. Among them, the separation layer is mainly formed of a synthetic polymer, has a separation function, but has poor mechanical strength when used alone, and thus is generally integrated with a substrate such as a nonwoven fabric, and a nanofiltration membrane material is formed by casting or coating a polymer solution as a separation layer on a substrate such as a nonwoven fabric as a support layer. The nonwoven fabric as the support layer is required to have excellent film formability to prevent excessive penetration of the polymer solution to the reverse side of the nonwoven fabric support; meanwhile, in order to ensure uniform thickness of the separation layer, the nonwoven fabric as the support layer is also required to have high dimensional stability, internal bonding strength, low hot water shrinkage and proper surface smoothness to resist deformation due to thermal and compressive stresses during the manufacturing process of the separation membrane.
Currently, in order to increase the flux of nanofiltration membranes, separation is often improved. For example, patent publication No. CN105498550A provides a nonwoven composite nanofiltration membrane, and a preparation method and application thereof. The nanofiltration membrane comprises a non-woven fabric supporting layer, a non-woven fabric transition layer and a non-woven fabric separating layer, raw material fibers with a three-layer structure are selected and combined, and are manufactured and formed through one-time lamination, so that the separating layer has good separating performance, the transition layer can improve the retention rate of nano cellulose of the separating layer, the supporting layer has good pressure resistance and physical and chemical stability, and higher flux and operation stability can be ensured. In the nanofiltration membrane, the supporting layer is mainly used for providing mechanical properties, the flux and the retention rate of the nanofiltration membrane are mainly determined by the separating layer, but the non-woven separating layer prepared in the patent has relatively poorer retention effect compared with the separating layer formed by coating a conventional polymer solution, and the retention rate is reduced when the composition of raw material fibers is regulated so as to improve the water flux, so that higher flux and retention rate are difficult to obtain simultaneously. In addition, if the conventional separation layer is directly adopted to replace the non-woven fabric separation layer in the patent, the combination condition between the non-woven fabric and the separation layer also can influence the coating effect of the separation layer, thereby influencing the flux and the retention rate of the nanofiltration membrane.
In view of the above, it is necessary to transfer the research focus to the support layer of the nanofiltration membrane, and to design a nonwoven fabric support material for the nanofiltration membrane, and a preparation method and application thereof, so as to solve the above-mentioned problems.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a non-woven fabric supporting material for a nanofiltration membrane, a preparation method and application thereof, wherein the pretreated tencel fiber, polyester fiber and bonding hot-melt fiber are mixed according to a specific proportion to prepare slurry, and the non-woven fabric supporting material is obtained through wet forming, drying, surface treatment and hot rolling calendaring, and has uniform surface, good hydrophilicity and excellent mechanical property, so that the non-woven fabric supporting material is applied to the preparation of the nanofiltration membrane, and the interception effect of the nanofiltration membrane is improved as much as possible while the water flux is improved.
In order to achieve the above purpose, the invention provides a preparation method of a non-woven fabric support material for a nanofiltration membrane, which comprises the following steps:
s1, mixing tencel fibers with water according to a preset first fiber concentration, and pulping after fluffing to obtain tencel fibers with a preset beating degree; adding water and a dispersing agent into the tencel fibers with the preset beating degree, and uniformly mixing to obtain first sizing agent with preset concentration;
s2, mixing chemical fibers with water according to a preset second fiber concentration, adding water and a dispersing agent after fluffing, and uniformly mixing to obtain second slurry with a preset concentration; the chemical fiber is a mixture of polyester fiber and bonding hot-melt fiber;
s3, mixing the first slurry and the second slurry according to a preset ratio to obtain third slurry; sequentially performing wet forming, squeezing and drying treatment on the third slurry to obtain a base material;
s4, carrying out surface treatment on the base material, drying, and carrying out hot rolling and calendaring molding to obtain the non-woven fabric supporting material for the nanofiltration membrane.
As a further improvement of the invention, in the step S1, the tencel fiber is formed by wet spinning viscose fiber of regenerated cellulose, the fineness of the tencel fiber is 1.7dtex, and the length is 6-10 mm; in the step S3, in the third slurry, the mass ratio of the tencel fiber to the polyester fiber to the bonding hot-melt fiber is 10-20:40-50:40-50; the fineness of the polyester fiber is 0.5-1 dtex, the length is 6-10 mm, and the melting point is 250 ℃; the fineness of the bonding hot-melt fiber is 1-2 dtex, the length is 2-8 mm, and the melting point is 160-200 ℃.
As a further improvement of the present invention, in step S4, the surface treatment includes the steps of:
mixing first polyvinyl alcohol and second polyvinyl alcohol with different alcoholysis degrees with water to prepare a surface treatment liquid;
and coating the surface treatment liquid on the surface of the substrate according to a preset coating amount.
As a further improvement of the invention, the polymerization degree of the first polyvinyl alcohol is 1600-1800, and the alcoholysis degree is 85-90%; the polymerization degree of the second polyvinyl alcohol is 1600-1900, and the alcoholysis degree is 98% -99%; in the surface treatment liquid, the mass ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 20-40:60-80.
As a further improvement of the invention, the surface treatment liquid also contains an antifoaming agent, and the mass of the antifoaming agent accounts for 0.05-0.15% of the total mass of the surface treatment liquid; the total mass of the first polyvinyl alcohol and the second polyvinyl alcohol accounts for 1% -2% of the total mass of the surface treatment liquid; the coating amount of the surface treatment liquid on the surface of the substrate is 1-2 g/m 2 。
As a further improvement of the present invention, in step S1, the freeness of the tencel fiber of the predetermined freeness is 50 to 80 ° SR.
As a further improvement of the present invention, in the step S1, the first fiber concentration is 2% to 4%, the defibering time is 10 to 15min, and the concentration of the first slurry is 0.8% to 1.2%.
As a further improvement of the present invention, in the step S2, the second fiber concentration is 1% to 2%, the defibering time is 10 to 15min, and the concentration of the second slurry is 0.8% to 1.2%.
In order to achieve the above purpose, the invention provides a non-woven fabric support material for a nanofiltration membrane, which is prepared by any one of the technical schemes.
The invention also provides application of the non-woven fabric support material for the nanofiltration membrane in the field of nanofiltration membrane preparation.
The beneficial effects of the invention are as follows:
(1) According to the preparation method of the non-woven fabric support material for the nanofiltration membrane, the tencel fibers are pretreated, the pretreated tencel fibers, the polyester fibers and the bonding hot-melt fibers are mixed according to a specific proportion for pulping, and the non-woven fabric support material with uniform surface, good hydrophilicity and excellent mechanical property is prepared by wet forming, drying, surface treatment and hot rolling and calendaring. When the non-woven fabric support material prepared by the method is applied to the preparation of the nanofiltration membrane, the water flux can be effectively improved, and the interception effect of the nanofiltration membrane can be improved as much as possible. In addition, the preparation method of the non-woven fabric support material for the nanofiltration membrane has the advantages of simple overall process and strong controllability, can meet the requirements of industrial production and application, and has higher practical application value.
(2) According to the preparation method of the non-woven fabric supporting material for the nanofiltration membrane, provided by the invention, the tencel fibers are fibrillated, and the beating degree of the tencel fibers is regulated and controlled, so that the tencel fibers with good hydrophilicity, small fiber diameter and large specific surface area can be obtained. On the basis, the non-woven fabric support material is mixed with polyester fibers and bonding hot-melt fibers, and simultaneously, the surface treatment is carried out by using polyvinyl alcohol, so that the surface performance of the non-woven fabric support material can be improved, the non-woven fabric support material has higher porosity and uniformity parameters, better processability, smaller pore diameter, higher porosity and higher smoothness. When the nanofiltration membrane is prepared based on the non-woven fabric supporting material provided by the invention, pinholes and offset phenomena can be remarkably reduced, a flat and uniform carrier support is provided for casting of casting solution, the excessive leakage problem of the casting solution is effectively prevented, and the nanofiltration membrane with good interlayer binding force, excellent mechanical property, stable morphological structure and moderate rigidity and softness can be prepared.
(3) According to the preparation method of the non-woven fabric support material for the nanofiltration membrane, provided by the invention, the alcoholysis degree of the polyvinyl alcohol used in the surface treatment liquid is regulated and controlled, so that the partially alcoholysis type polyvinyl alcohol and the completely alcoholysis type polyvinyl alcohol are matched for use, and the stability and the water resistance of emulsion are improved. The non-woven fabric treated by the surface treatment mode provided by the invention has good adhesion force after being dried, can greatly improve the mechanical property index of the product, and the formed coating has good grease resistance.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to specific embodiments.
In addition, it should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention provides a preparation method of a non-woven fabric supporting material for a nanofiltration membrane, which comprises the following steps:
s1, mixing tencel fibers with water according to a preset first fiber concentration, and pulping after fluffing to obtain tencel fibers with a preset beating degree; adding water and a dispersing agent into the tencel fibers with the preset beating degree, and uniformly mixing to obtain first sizing agent with preset concentration;
s2, mixing chemical fibers with water according to a preset second fiber concentration, adding water and a dispersing agent after fluffing, and uniformly mixing to obtain second slurry with a preset concentration; the chemical fiber is a mixture of polyester fiber and bonding hot-melt fiber;
s3, mixing the first slurry and the second slurry according to a preset ratio to obtain third slurry; sequentially performing wet forming, squeezing and drying treatment on the third slurry to obtain a base material;
s4, carrying out surface treatment on the base material, drying, and carrying out hot rolling and calendaring molding to obtain the non-woven fabric supporting material for the nanofiltration membrane.
In the step S1, the tencel fiber is formed by wet spinning of viscose fiber of regenerated cellulose, wherein the fineness of the tencel fiber is 1.7dtex, and the length of the tencel fiber is 6-10 mm; the beating degree of the tencel fiber with the preset beating degree is 50-80 DEG SR, and the size of the tencel fiber fibril formed after beating is about 10-900 nm; the concentration of the first fiber is 2% -4%, the defibering time is 10-15 min, and the concentration of the first slurry is 0.8% -1.2%.
In the step S2, the concentration of the second fiber is 1% -2%, the defibering time is 10-15 min, and the concentration of the second slurry is 0.8% -1.2%.
In the step S3, the mass ratio of the tencel fiber to the polyester fiber to the bonding hot-melt fiber in the third slurry is 10-20:40-50:40-50. Wherein the fineness of the polyester fiber is 0.5-1 dtex, the length is 6-10 mm, and the melting point is 250 ℃; the bonding hot-melt fiber is an undrawn fiber, the material of the bonding hot-melt fiber is modified COPET, the fineness is 1-2 dtex, the length is 2-8 mm, and the melting point is 160-200 ℃.
In step S4, the surface treatment includes the steps of:
mixing first polyvinyl alcohol and second polyvinyl alcohol with different alcoholysis degrees with water to prepare a surface treatment liquid;
and coating the surface treatment liquid on the surface of the substrate according to a preset coating amount.
The polymerization degree of the first polyvinyl alcohol is 1600-1800, and the alcoholysis degree is 85-90%; the polymerization degree of the second polyvinyl alcohol is 1600-1900, and the alcoholysis degree is 98% -99%; in the surface treatment liquid, the mass ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 20-40:60-80.
The surface treatment liquid also contains an antifoaming agent, and the mass of the antifoaming agent accounts for 0.05-0.15% of the total mass of the surface treatment liquid; the total mass of the first polyvinyl alcohol and the second polyvinyl alcohol accounts for 1% -2% of the total mass of the surface treatment liquid; the coating amount of the surface treatment liquid on the surface of the substrate is 1-2 g/m 2 。
The invention provides a non-woven fabric supporting material for a nanofiltration membrane, which is prepared by the technical scheme.
The invention also provides application of the non-woven fabric support material for the nanofiltration membrane in the field of nanofiltration membrane preparation.
The nonwoven fabric support material for nanofiltration membranes, and the preparation method and application thereof provided by the invention are specifically described below with reference to specific examples.
Example 1
The embodiment provides a preparation method of a non-woven fabric supporting material for a nanofiltration membrane, which comprises the following steps:
s1, weighing tencel fibers according to 15% of the total fiber weight, putting the tencel fibers into a pulper with water, controlling the concentration of the tencel fibers to be 3%, after fluffing for 12min, circularly pulping by a double-disc mill until the beating degree is 60 DEG SR, putting the tencel fibers into another pulp mixing tank, adding water and a dispersing agent, and uniformly stirring to ensure that the concentration of the tencel fibers is 1%, thereby obtaining first pulp;
s2, weighing polyester fibers according to 42.5% of the total amount of the fibers, weighing equal amounts of bonding hot-melt fibers, mixing the fibers, putting the mixed fibers into another pulper with water, controlling the concentration of the fibers to be 1.5%, defibering the fibers for 12min, putting the fibers into another pulp mixing tank, adding water and a dispersing agent, and uniformly stirring the fibers to ensure that the total concentration of the polyester fibers and the bonding hot-melt fibers is 1%, thereby obtaining second pulp;
s3, mixing the two slurries prepared in the step S2 and the step S3 to obtain a third slurry; the mass ratio of the tencel fiber to the polyester fiber to the bonding hot-melt fiber in the third slurry is 15:42.5:42.5; conveying the third slurry to an inclined wire wet former for wet forming to obtain a wet fiber web; squeezing, strengthening and drying a wet fiber web by a drying cylinder to obtain a base material;
s4, mixing the first polyvinyl alcohol, the second polyvinyl alcohol, the defoaming agent and water to prepare a surface treatment liquid; the surface treatment liquid was added at a rate of 1.5g/m 2 Coating the surface of the substrate with the coating amount of (a); and (5) after drying, carrying out hot rolling and calendaring molding to obtain the non-woven fabric support material for the nanofiltration membrane.
Wherein the mass of the defoaming agent accounts for 0.1% of the total mass of the surface treatment liquid; the total mass of the first polyvinyl alcohol and the second polyvinyl alcohol accounts for 1.5% of the total mass of the surface treatment liquid; the mass ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 30:70; the first polyvinyl alcohol had a degree of polymerization of 1700, an alcoholysis degree of 88%, and the second polyvinyl alcohol had a degree of polymerization of 1700, and an alcoholysis degree of 99%.
The performance test data of the nonwoven fabric for nanofiltration membrane prepared in this example are shown in table 1.
TABLE 1 Performance parameters of nonwoven fabrics for nanofiltration membranes prepared in EXAMPLE 1
| Detecting items | Detection result |
| Breadth (mm) | 1100 |
| Quantification (g) | 78 |
| Thickness (μm) | 98 |
| Tensile Strength (KN/m) | Longitudinal direction: 7.2; transverse direction: 3.5 |
| Smoothness(s) | Front face: 32; and (3) reverse: 24 |
| Air permeability (cm) 3 /cm 2 /s) | 1.2 |
| Average pore diameter (mum) | 4.2 |
| Porosity (%) | 28 |
As can be seen from table 1, the nonwoven fabric prepared in this example has higher strength, smoothness, porosity and smaller average pore diameter, and can meet the performance requirement of the nonwoven fabric for nanofiltration membrane.
Examples 2 to 5 and comparative examples 1 to 5
Examples 2 to 5 and comparative examples 1 to 5 respectively provide a method for preparing a nonwoven fabric support material for nanofiltration membranes, which is different from example 1 in that the process parameters such as the mass ratio of tencel fibers, polyester fibers and bonding hot-melt fibers, the beating degree of tencel fibers, the mass ratio of first polyvinyl alcohol and second polyvinyl alcohol are changed, the process parameters corresponding to each example and comparative example are shown in table 2, and the rest steps and process parameters are the same as those of example 1, and are not repeated herein.
Table 2 process parameters for examples 2 to 5 and comparative examples 1 to 5
The performance of the nonwoven fabrics for nanofiltration membranes prepared in examples 2 to 5 and comparative examples 1 to 5 was examined, and the results are shown in table 3.
TABLE 3 Performance parameters of nonwoven fabrics for nanofiltration membranes prepared in examples 2 to 5 and comparative examples 1 to 5
As can be seen from table 3: by changing the proportion of the tencel fibers in the nanofiltration membrane non-woven fabric supporting material, the tensile strength, smoothness, pore diameter and porosity of the obtained non-woven fabric product are changed, and as the content of the tencel fibers is increased, the pore diameter of the non-woven fabric prepared by blending the tencel fibers with the polyester fibers and the bonding hot-melt fibers is reduced, the smoothness and the porosity are improved, so that the coating effect of the nanofiltration membrane is greatly improved, and the water throughput of the nanofiltration membrane is improved. However, when the proportion of the silk fiber reaches 20% or even 30%, the tensile strength of the nonwoven fabric is reduced. Meanwhile, as the beating degree of the tencel fiber is increased, the diameter of the tencel fiber is reduced, and the porosity and the strength are increased and then reduced. If only a single kind of polyvinyl alcohol is used, the foam is increased in the actual preparation process, the surface sizing effect is affected, and the mechanical property, smoothness and porosity of the non-woven fabric are further affected.
Example 6
The embodiment provides an application of a non-woven fabric supporting material for a nanofiltration membrane, which specifically comprises the following steps:
s1, dissolving 18% of polysulfone in 82% of dimethylformamide at 80 ℃ to obtain a film-forming solution, then coating the film-forming solution on a coating area of a prepared non-woven fabric support material for a nanofiltration membrane at a thickness of 0.050mm, and after phase separation in solidified water at 20 ℃, washing to remove residual solvent in the membrane by a water bath, and then rolling at a tension of 100N to obtain the non-woven fabric for the nanofiltration membrane support with a polysulfone membrane;
s2, immersing the nanofiltration membrane supporting non-woven fabric with the polysulfone membrane prepared in the step S1 in 0.3% piperazine (PIP) aqueous solution for about 1min, wherein the piperazine aqueous solution contains 0.1% Sodium Dodecyl Sulfate (SDS); removing excessive solution on the front and back surfaces of the support non-woven fabric soaked by the PIP solution by using a rubber roller, and then contacting the support non-woven fabric with an organic phase for 30s, wherein the organic phase contains 0.1% of trimesoyl chloride, 0.6% of polydimethylsiloxane and n-hexane; and (3) forming an ultrathin piperazine amide layer through interfacial polymerization, and then placing the ultrathin piperazine amide layer in a vacuum oven at 90 ℃ for 10min to form the nanofiltration membrane.
The nonwoven fabric support materials for nanofiltration membranes prepared in examples 1 to 5 and comparative examples 1 to 5 were used, respectively, in the above manner to prepare corresponding nanofiltration membranes.
With 2000ppm (parts per million by mass) Na 2 SO 4 The water solution was tested for the performance of nanofiltration membrane such as water throughput, desalination rate, membrane peel strength, permeability, etc. at a pressure of 1 MPa.
Wherein the water throughput and the desalination rate can be calculated by the following formulas, respectively:
flux of water F (L/m) 2 h)：
Desalination rate R (%):
in the above formula, V is the solvent permeation amount (L), A is the effective membrane area (m 2 ) T is the time (h) of solvent permeation, cp is the permeate concentration, C f Is the feed solution concentration.
The film peel strength is tested by using a GB/T25256:2010 standard test method, and specifically comprises the following steps:
the prepared separation membrane was cut into test pieces having a width of 25.+ -. 0.5mm and a length of 150 mm. At one end of the sample, the polysulfone layer and the support layer are separated. The polysulfone layer was then fixed on one clamp of a constant speed tensile tester and the support layer of the separation membrane was fixed on the other clamp, with a sample length between the clamps of 50mm. The separation film was continuously peeled at a constant speed of 180℃along the longitudinal principal axis of the specimen at a tensile speed of 300.+ -.10 mm/min or at a suitable tensile speed, and the average value of the peel strengths from the time when the strength was stabilized until the specimen length between the clamps became 65mm was calculated, and the average value of the film peel strengths in the longitudinal and transverse directions was taken as an integer to obtain the film peel strength of the separation film in mN/15mm.
The permeability of the casting solution is tested by adopting a visual method, and the method specifically comprises the following steps:
the back surface of the film was observed, and the degree of bleeding of the casting solution was evaluated on A1 to A5 scale, and the evaluation value A4 or more indicated "acceptable", and specific evaluation criteria of A1 to A5 were as follows:
a5: the casting solution did not bleed out.
A4: the casting solution has little exudation, and the penetration area ratio is less than 5%.
A3: the casting solution has exudation, and the penetration area ratio is between 5% and 50%.
A2: most of the areas were exuded by the casting solution, with a penetration area ratio between 51% and 80%.
A1: the whole area is exuded by the casting solution, and the penetration area ratio is 100%.
The performance of nanofiltration membranes prepared using the nonwoven fabrics provided in examples 1 to 5 and comparative examples 1 to 5 as support materials were measured in the above manner, respectively, and the results are shown in table 4.
TABLE 4 Properties of nanofiltration membranes prepared based on nonwoven fabric support materials provided in different examples and comparative examples
As can be seen from Table 4, the nanofiltration membranes prepared in examples 1, 4 and 5 have good performances, meet the relevant requirements, and the nanofiltration membranes prepared in examples 2 and 3 have good performances except for permeability, meet the relevant requirements, and the permeability is shown to have a small overflow but is still acceptable. The nanofiltration membranes prepared in comparative examples 2, 4 and 5 have unstable performance indexes, relatively low water flux and membrane peeling strength, and the nanofiltration membranes prepared in comparative examples 1 and 3 have obviously poor permeability and can not meet the use requirements. Therefore, the prepared nanofiltration membrane has excellent performance only based on the specific mass ratio of the tencel fiber, the polyester fiber and the bonding hot-melt fiber, the beating degree of the tencel fiber and the mass ratio of the first polyvinyl alcohol to the second polyvinyl alcohol to prepare the nonwoven fabric support material for the nanofiltration membrane, so as to meet the application requirements.
In summary, the invention provides a non-woven fabric supporting material for a nanofiltration membrane, and a preparation method and application thereof. The invention obtains the tencel fiber with preset beating degree by preprocessing the tencel fiber; dispersing the raw materials into first slurry, mixing the first slurry with second slurry containing polyester fibers and bonding hot-melt fibers according to a preset proportion, pulping, wet forming, drying, surface treatment, hot rolling and calendaring to obtain the non-woven fabric support material for the high-flux nanofiltration membrane. Through the mode, the non-woven fabric support material obtained by the invention has the advantages of uniform surface, good hydrophilicity and excellent mechanical property, and can improve the interception effect of the nanofiltration membrane as much as possible while improving the water flux when being applied to the preparation of the nanofiltration membrane, thereby having higher practical application value.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention.
Claims (10)
1. The preparation method of the non-woven fabric supporting material for the nanofiltration membrane is characterized by comprising the following steps of:
s1, mixing tencel fibers with water according to a preset first fiber concentration, and pulping after fluffing to obtain tencel fibers with a preset beating degree; adding water and a dispersing agent into the tencel fibers with the preset beating degree, and uniformly mixing to obtain first sizing agent with preset concentration;
s2, mixing chemical fibers with water according to a preset second fiber concentration, adding water and a dispersing agent after fluffing, and uniformly mixing to obtain second slurry with a preset concentration; the chemical fiber is a mixture of polyester fiber and bonding hot-melt fiber;
s3, mixing the first slurry and the second slurry according to a preset ratio to obtain third slurry; sequentially performing wet forming, squeezing and drying treatment on the third slurry to obtain a base material;
s4, carrying out surface treatment on the base material, drying, and carrying out hot rolling and calendaring molding to obtain the non-woven fabric supporting material for the nanofiltration membrane.
2. The method for preparing a nonwoven fabric support material for nanofiltration membranes according to claim 1, wherein the method comprises the steps of: in the step S1, the tencel fiber is formed by wet spinning of viscose fiber of regenerated cellulose, wherein the fineness of the tencel fiber is 1.7dtex, and the length of the tencel fiber is 6-10 mm; in the step S3, in the third slurry, the mass ratio of the tencel fiber to the polyester fiber to the bonding hot-melt fiber is 10-20:40-50:40-50; the fineness of the polyester fiber is 0.5-1 dtex, the length is 6-10 mm, and the melting point is 250 ℃; the fineness of the bonding hot-melt fiber is 1-2 dtex, the length is 2-8 mm, and the melting point is 160-200 ℃.
3. The method for preparing a nonwoven fabric support material for nanofiltration membranes according to claim 1, wherein the method comprises the steps of: in step S4, the surface treatment includes the steps of:
mixing first polyvinyl alcohol and second polyvinyl alcohol with different alcoholysis degrees with water to prepare a surface treatment liquid;
and coating the surface treatment liquid on the surface of the substrate according to a preset coating amount.
4. The method for producing a nonwoven fabric support material for nanofiltration membranes according to claim 3, wherein the method comprises the steps of: the polymerization degree of the first polyvinyl alcohol is 1600-1800, and the alcoholysis degree is 85-90%; the polymerization degree of the second polyvinyl alcohol is 1600-1900, and the alcoholysis degree is 98% -99%; in the surface treatment liquid, the mass ratio of the first polyvinyl alcohol to the second polyvinyl alcohol is 20-40:60-80.
5. The method for producing a nonwoven fabric support material for nanofiltration membranes according to claim 3, wherein the method comprises the steps of: the surface treatment liquid also contains an antifoaming agent, and the mass of the antifoaming agent accounts for 0.05-0.15% of the total mass of the surface treatment liquid; the total mass of the first polyvinyl alcohol and the second polyvinyl alcohol accounts for 1% -2% of the total mass of the surface treatment liquid; the coating amount of the surface treatment liquid on the surface of the substrate is 1-2 g/m 2 。
6. The method for preparing a nonwoven fabric support material for nanofiltration membranes according to claim 1, wherein the method comprises the steps of: in step S1, the degree of beating of the tencel fiber of the predetermined degree of beating is 50 ° to 80 ° SR.
7. The method for preparing a nonwoven fabric support material for nanofiltration membranes according to claim 1, wherein the method comprises the steps of: in the step S1, the concentration of the first fiber is 2% -4%, the defibering time is 10-15 min, and the concentration of the first slurry is 0.8% -1.2%.
8. The method for preparing a nonwoven fabric support material for nanofiltration membranes according to claim 1, wherein the method comprises the steps of: in the step S2, the concentration of the second fiber is 1% -2%, the defibering time is 10-15 min, and the concentration of the second slurry is 0.8% -1.2%.
9. A nonwoven fabric support material for nanofiltration membranes, characterized in that the nonwoven fabric support material is prepared according to the preparation method of any one of claims 1 to 8.
10. Use of the nonwoven fabric support material for nanofiltration membranes as claimed in claim 9, wherein: the non-woven fabric support material is used in the field of nanofiltration membrane preparation.
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