CN110787650A - Preparation method of porous nano antibacterial particles and composite hollow membrane - Google Patents
Preparation method of porous nano antibacterial particles and composite hollow membrane Download PDFInfo
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0039—Inorganic membrane manufacture
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
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- B01D2325/36—Hydrophilic membranes
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- B01D2325/48—Antimicrobial properties
Abstract
The invention discloses a preparation method of porous nano antibacterial particles and a composite hollow membrane and the composite hollow membrane, wherein the preparation method of the porous nano antibacterial particles comprises the steps of adding titanium tetrachloride into water, adding ammonium sulfate and concentrated hydrochloric acid, stirring, heating, keeping the temperature, adding concentrated ammonia water, cooling, adding β -cyclodextrin, stirring to obtain a glue solution, carrying out hydrothermal reaction on the glue solution to obtain titanium dioxide nano particle sol, adding CuCl2 and sodium dodecyl benzene sulfonate into the particle sol, stirring, adding a reducing agent and pure water, mixing to obtain a reactant, carrying out photoinduction reaction on the reactant to obtain copper-coated titanium dioxide nano particles, washing the copper-coated particles, drying and calcining to obtain the porous copper-coated titanium dioxide nano antibacterial particles.
Description
Technical Field
The invention relates to the technical field of membrane separation, in particular to a porous copper-coated titanium dioxide nano antibacterial particle, a preparation method of a composite hollow fiber filter membrane with the particle and the composite hollow fiber filter membrane.
Background
With the rapid development of national economy and the continuous improvement of the living standard of people, the requirements on the environment, particularly the water environment safety, are higher and higher. In order to obtain more stable and higher effluent quality, membrane water treatment technology is increasingly adopted in sewage treatment and drinking water treatment processes, wherein the application of hollow fiber ultra/micro filtration membranes is more and more extensive. Membrane Bioreactor (MBR) and membrane filtration of tap water have become the most promising wastewater and water treatment technologies, and lining-enhanced hollow fiber composite membranes and homogeneous hollow fiber membranes have been rapidly developed by virtue of their superior performance. The greatest challenge in the application of hollow fiber ultra/microfiltration membranes arises from fouling of the membrane surface, and frequent chemical cleaning not only increases the operating and maintenance costs, but also reduces the useful life of the membrane. Therefore, the anti-pollution performance of the membrane is increased, and the anti-pollution performance of the membrane is of great significance for expanding the application of the membrane.
The biggest challenge in the application of hollow fiber filtration membranes is membrane fouling, and especially microbial fouling has a great influence on the operation and maintenance of the membranes. In order to reduce the pollution tendency of the membrane, researchers and engineers adopt a plurality of methods, wherein increasing the hydrophilicity of the surface of the membrane is an effective way for improving the membrane flux of the hollow fiber filter membrane, a plurality of researchers introduce nano ceramic particles into the membrane material, which can improve the hydrophilicity of the membrane and is beneficial to increasing the membrane flux, and increasing the hydrophilicity of the surface of the membrane is an effective way for improving the membrane flux of the hollow fiber membrane, but the bonding force between the nano ceramic particles and the membrane material is weak, and the nano particles can be continuously separated from the membrane material and run off, and finally lose the effect.
The hollow fiber membrane is in a pressure filtration mode, pollutants are easy to deposit on the surface of the membrane, and membrane pollution caused by microorganisms such as bacteria becomes a most important component of the pollution of the hollow fiber membrane in a water treatment process, so that the water flux and the separation performance of the membrane are obviously reduced, the membrane needs to be cleaned or replaced regularly and continuously, the service life and the efficiency of the membrane are seriously affected, and the use cost is increased. Therefore, how to improve the antibacterial performance of the membrane surface becomes the key point of the development of the anti-pollution performance of the hollow fiber membrane. Many researches focus on loading antibacterial substances on the surface of the membrane to construct the membrane surface with antibacterial performance, thereby effectively reducing biological pollution.
The antibacterial material mainly comprises inorganic, organic and natural macromolecular antibacterial agents. The research and application of the nano-silver antibacterial agent of the inorganic antibacterial agent are the most extensive, the market share is high, but the countries in Europe and America have found that the nano-silver has safety risks to human health, so that the related application of the nano-silver material is limited. Copper is a trace element needed by human bodies, and in 3 months of 2008, the united states Environmental Protection Agency (EPA) confirms that copper can kill harmful and possibly fatal germs, and copper is the only metal bacteriostatic material which is certified by the united states Environmental Protection Agency (EPA), so that the adoption of nano copper-based antibacterial agents with biological safety becomes a safer choice. This is particularly important for hollow fibre filtration membranes used in drinking water treatment. The copper-coated titanium dioxide novel nano antibacterial particles (shown in figures 1 and 3) have a long-acting metal ion release effect, can have a good antibacterial and mildewproof function under a dark condition, and are novel nano antibacterial particles with biological safety. But after entering the hollow fiber filter membrane material, the antibacterial agent can fall off and run off, and the antibacterial effect cannot be maintained.
Therefore, how to overcome the defect that the conventional hollow fiber filter membrane cannot give consideration to both good antibacterial property of the membrane surface and large membrane flux is a problem to be solved in the industry.
Disclosure of Invention
The invention provides a preparation method of porous nano antibacterial particles and a composite hollow fiber filter membrane which have high water flux, are resistant to bacterial pollution and easy to clean, and the composite hollow fiber filter membrane prepared by the preparation method, and aims to solve the technical problem that the conventional hollow fiber filter membrane cannot give consideration to both high antibacterial performance of the membrane surface and high membrane flux.
The invention provides a preparation method of porous copper-clad titanium dioxide nano antibacterial particles, which comprises the following steps:
step 1: dripping titanium tetrachloride into an ice water bath, stirring, dripping aqueous solution of ammonium sulfate and concentrated hydrochloric acid, and stirring below a first set temperature to obtain a mixture;
step 2: heating the mixture to a second set temperature, preserving heat for 1h, adding concentrated ammonia water, adjusting the pH value to 5-7, cooling to room temperature, and standing for 12h to obtain titanium dioxide sol;
and 4, step 4: putting the titanium dioxide glue solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 6-12h at 180 ℃ to obtain titanium dioxide nanoparticle sol;
and 5: adding CuCl2Adding sodium dodecyl benzene sulfonate into the titanium dioxide nano-particle sol, dispersing by ultrasonic wave,
after the pH value is adjusted to 5-7, adding a reducing agent formic acid and pure water, and uniformly mixing to prepare a reactant;
step 6: placing the reactant in ultraviolet light for light-induced reaction, and performing light reduction reaction on the surface of the titanium dioxide nano-particles to generate metal copper particles so as to prepare aqueous dispersion of the copper-coated titanium dioxide nano-particles;
and 7: and washing the aqueous dispersion of the copper-clad titanium dioxide nano-particles with pure water and ethanol, drying and calcining to prepare the porous copper-clad titanium dioxide nano-antibacterial particles.
Preferably, the first set temperature is 15 ℃, the second set temperature is 93-97 ℃, and β -cyclodextrin added into the titanium dioxide sol accounts for 15-110% of the weight of the titanium tetrachloride.
Preferably, the ultrasonic dispersion time is 5-60 min; placing the reactant under ultraviolet light for 10-500 minutes to perform the photoinduction reaction; the calcination is carried out at 400-750 ℃.
Preferably, the reactant is prepared from the following components in percentage by weight:
0.2-20% of titanium dioxide nano-particle sol; CuCl20.2-5%; 0.1 to 5 percent of sodium dodecyl benzene sulfonate;
formic acid: 0.5-7.5%; 79.2 to 99 percent of pure water.
The invention also provides a preparation method of the composite hollow fiber filter membrane with the porous copper-coated titanium dioxide nano antibacterial particles, which comprises the following steps:
step 1: grinding and crushing the porous copper-clad titanium dioxide nano antibacterial particles, adding the crushed particles into a solvent, and adding a polymer while performing ultrasonic dispersion or strong stirring to gradually increase the viscosity of a polymer solution so that the porous copper-clad titanium dioxide nano antibacterial particles cannot be agglomerated after being uniformly dispersed;
step 2: gradually adding the polymer solution containing the porous copper-clad titanium dioxide nano antibacterial particles into a membrane casting solution, strongly stirring for 2-18h at 60-100 ℃ to uniformly disperse the porous copper-clad titanium dioxide nano antibacterial particles into the membrane casting solution, and defoaming in vacuum to prepare the porous copper-clad titanium dioxide nano antibacterial particle-polymer membrane casting solution;
and step 3: spinning the porous copper-clad titanium dioxide nano antibacterial particle-polymer casting solution by a conventional dry-wet method to obtain a hollow fiber filter membrane filament, and washing the prepared hollow fiber filter membrane filament with purified water for at least 24 hours to obtain the composite hollow fiber filter membrane of the porous copper-clad titanium dioxide nano antibacterial particle.
Preferably, the membrane casting solution is a polymer solution, and is prepared from a polymer, a pore-forming agent and a solvent, wherein the weight ratio of the polymer: the solvent is 10-40: 50-90.
Preferably, the polymer is at least one of polyvinylidene fluoride (PVDF), Polysulfone (PS), Polyethersulfone (PES), Polyacrylonitrile (PAN) or polyvinyl chloride (PVC).
Preferably, the pore-forming agent is at least one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and LiCl, and the content of the pore-forming agent in the membrane casting solution is 0.2-20%.
Preferably, the solvent is at least one of N-N Dimethylformamide (DMF), N-N dimethylacetamide (DMAc), methyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP).
Preferably, the concentration of the polymer in the polymer solution is 10-40 wt%.
Preferably, the concentration of the porous copper-coated titanium dioxide nano antibacterial particles in the polymer solution relative to the polymer is 0.001-10 wt%.
The invention further provides a porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane, which comprises a hollow fiber filter membrane formed by a compact layer on the surface of the membrane and a microporous layer on the inner surface of the membrane, and porous copper-clad titanium dioxide nano antibacterial particles which are dispersedly embedded in the hollow fiber filter membrane; the density of the porous copper-clad titanium dioxide nano antibacterial particles contained in the compact layer is greater than that of the porous copper-clad titanium dioxide nano antibacterial particles contained in the microporous layer.
The porous copper-coated titanium dioxide nano antibacterial particles provided by the invention have good hydrophilicity, more internal through holes and small aperture (<2 nm) and the like, and (1) after the nano antibacterial particles are compounded with the hollow fiber filter membrane, the surface hydrophilicity of the membrane can be increased due to the excellent hydrophilicity of the nano antibacterial particles, so that the water flux of the membrane can be improved, and the pollution can be reduced. (2) Abundant perforating holes in the nano antibacterial particles can allow water to pass through, and membrane pores cannot be blocked. Thereby greatly improving the membrane flux and overcoming the defect that the common nano particles block the membrane pores and are not beneficial to the membrane flux. (3) The nano antibacterial particles are internally provided with a large number of through holes, and the membrane liquid can penetrate into the holes to form wedges to firmly fix the nano antibacterial particles, so that the binding force between the nano antibacterial particles and the membrane material is greatly increased, and the antibacterial effect of the nano antibacterial particles is ensured not to be attenuated along with time (see figure 4), thereby obviously improving the membrane flux and ensuring the permanent antibacterial performance of the membrane. (4) Copper-coated TiO 22The nano particles have excellent antibacterial performance, can be enriched on the surface of the membrane after being compounded into the membrane material, can greatly improve the antibacterial and anti-pollution performance of the surface of the hollow fiber filter membrane, has no biological hazard to human bodies and environment, and has no ecological risk in large-scale use. And the copper compound is cheaper than the silver compound, so that the manufacturing cost of the nano antibacterial particles can be reduced, and the manufacturing cost of the antibacterial film can be reduced. (5) The composite hollow fiber filter membrane provided by the invention has water fluxThe antibacterial and anti-pollution performance is improved, the chemical cleaning frequency of the membrane can be greatly reduced, and the service life of the membrane is prolonged, so that the operation and maintenance cost of the membrane is reduced, and the operation and maintenance cost of a water treatment project is reduced.
Drawings
FIG. 1 is a schematic diagram of a conventional nano-ceramic particle;
FIG. 2 is a schematic view of a porous copper-coated titanium dioxide nano antibacterial particle of the present invention;
FIG. 3 is a schematic diagram of the combination of common nano-ceramic particles with membrane material;
FIG. 4 is a schematic view of the combination of the porous copper-coated titanium dioxide nano antibacterial particles and the hollow fiber filter membrane of the present invention;
FIG. 5 is a schematic cross-sectional view of the porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane of the present invention.
Detailed Description
The invention provides a preparation method of porous copper-clad titanium dioxide nano antibacterial particles, which comprises the following steps:
dripping titanium tetrachloride into an ice water bath, stirring strongly, dripping aqueous solution of ammonium sulfate and concentrated hydrochloric acid into the obtained titanium tetrachloride aqueous solution, stirring at the temperature below 15 ℃ to obtain a mixture, heating the mixture to 93-97 ℃, keeping the temperature for 1h, adding concentrated ammonia water, adjusting the pH value to 5-7, cooling to room temperature, standing for 12h to obtain titanium dioxide sol, adding β -cyclodextrin accounting for 15-110 wt% of titanium tetrachloride into the titanium dioxide sol, stirring strongly, adjusting the pH value to 5-6, continuously stirring for 1h to obtain titanium dioxide glue solution, filling the titanium dioxide glue solution into a hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 6-12h to obtain titanium dioxide nanoparticle sol, adding CuCl, and stirring strongly to obtain titanium dioxide nanoparticle sol2And adding sodium dodecyl benzene sulfonate into the titanium dioxide nano-particle sol, performing ultrasonic dispersion for 5-60min, adjusting the pH value to 5-7, adding reducing agent formic acid and pure water, and uniformly mixing to obtain the reactant. The reactant is prepared from the following components in percentage by weight: 0.2-20% of titanium dioxide nano-particle sol; CuCl20.2-5%; 0.1 to 5 percent of sodium dodecyl benzene sulfonate; formic acid: 0.5-7.5%; 79.2 to 99 percent of pure water. Exposing the reactants to ultraviolet lightCarrying out light induction reaction for 10-500 minutes, and carrying out light reduction reaction on the surface of the titanium dioxide nano-particles to generate metal copper particles so as to prepare the aqueous dispersion of the copper-coated titanium dioxide nano-particles; washing the aqueous dispersion of the copper-clad titanium dioxide nano-particles with pure water and ethanol, drying, and calcining at the temperature of 400-750 ℃ to prepare the porous copper-clad titanium dioxide nano-antibacterial particles.
The invention also provides a preparation method of the composite hollow fiber filter membrane with the porous copper-clad titanium dioxide nano antibacterial particles, which comprises the following steps:
grinding and crushing a proper amount of porous copper-clad titanium dioxide nano antibacterial particles, adding the crushed particles into a solvent, and adding a polymer while performing ultrasonic dispersion or strong stirring to gradually increase the viscosity of a polymer solution so that the porous copper-clad titanium dioxide nano antibacterial particles cannot be agglomerated after being uniformly dispersed. Gradually adding the polymer solution containing the porous copper-clad titanium dioxide nano antibacterial particles into the casting solution, strongly stirring for 2-18h at 60-100 ℃ to uniformly disperse the porous copper-clad titanium dioxide nano antibacterial particles into the casting solution, and performing vacuum defoaming to prepare the porous copper-clad titanium dioxide nano antibacterial particle-polymer casting solution.
The casting solution is a polymer solution and is prepared from a polymer, a pore-foaming agent and a solvent, wherein the polymer: the solvent is 10-40: 50-90.
The polymer suitable for preparing the polymer solution is at least one of polyvinylidene fluoride (PVDF), Polysulfone (PS), Polyethersulfone (PES), Polyacrylonitrile (PAN) or polyvinyl chloride (PVC). The solvent may be an organic solvent. The solvent is at least one of N-N Dimethylformamide (DMF), N-N dimethylacetamide (DMAc), methyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP). The pore-forming agent is at least one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and LiCl, and the content of the pore-forming agent in the membrane casting solution is 0.2-20%.
The concentration of the polymer in the polymer solution depends on the kind of polymer used. Typically, the concentration of polymer may be between about 10 and 40 wt%. The polymer concentration may be suitably selected depending on the polymer to be used. The concentration of the porous copper-coated titanium dioxide nano antibacterial particles in the polymer solution relative to the polymer is 0.001-10 wt%. The dispersion of the porous copper-clad titanium dioxide nano antibacterial particles in the composite hollow fiber filter membrane can be changed by adjusting the concentration of the porous copper-clad titanium dioxide nano antibacterial particles in the polymer solution.
Spinning the porous copper-clad titanium dioxide nano antibacterial particle-polymer casting solution by a conventional dry-wet method to obtain a hollow fiber filter membrane filament, and washing the prepared hollow fiber filter membrane filament with purified water for at least 24 hours to obtain the composite hollow fiber filter membrane of the porous copper-clad titanium dioxide nano antibacterial particle.
The invention is further illustrated by the following figures and examples.
Example 1
1. Preparation of porous copper-coated titanium dioxide nanoparticles
Titanium tetrachloride is used as a precursor, strong stirring is carried out in ice water bath, and 100ml of TiCl is added4Dropping pure water, dropping water solution dissolved with ammonium sulfate and concentrated hydrochloric acid into the obtained titanium tetrachloride water solution, stirring the mixture, controlling the temperature below 15 ℃ in the mixing process, heating the mixture to 95 ℃ and preserving the temperature for 1h, adding concentrated ammonia water, adjusting the pH value to about 6, cooling to room temperature, standing for 12h, then washing for many times by adopting a method of pure water, precipitating, removing supernatant, adding β -cyclodextrin into the cleaned titanium dioxide sol under the condition of strong stirring, wherein the adding amount of β -cyclodextrin is 90 percent of titanium tetrachloride, adjusting the pH value of the solution to 5-6, continuously stirring for 1h, filling into a hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 8h, and obtaining TiO2Nano antibacterial particle sol.
Firstly, adding CuCl into titanium dioxide nano antibacterial particle sol2Dispersing sodium dodecyl benzene sulfonate by ultrasonic wave for 5-60min, adjusting pH value to 5-7, and adding reducing agent formic acid to obtain the reactant. The reactant comprises the following components in percentage by weight:
2% of titanium dioxide nano antibacterial particle glue solution; CuCl21.2 percent; 0.5 percent of sodium dodecyl benzene sulfonate; 2.5 percent of formic acid; the residue is leftThe lower is pure water.
Uniformly mixing the prepared reactants, then carrying out light induction reaction, placing the reactants under ultraviolet light for 200 minutes, and carrying out light reduction reaction on the surface of the nano titanium dioxide by using the nano titanium dioxide as an inducer of photochemical reaction to produce metal copper particles so as to prepare a composite antibacterial material of copper-coated nano titanium dioxide and form aqueous dispersion;
washing the prepared porous copper-coated nano titanium dioxide composite antibacterial material with pure water and ethanol, drying, and calcining at the temperature of 400-750 ℃ to obtain the porous copper-coated TiO2Nano antibacterial particles.
2. Preparation of porous copper-coated titanium dioxide nano antibacterial particle-composite antibacterial hollow fiber filter membrane casting solution
The formula of the casting solution is as follows: 16.5% of PVDF and 165 g; DMAc 69.7%, 697 g; PVP-K303.6%, 36 g; PEG40010.2%,102 g; porous copper-coated titanium dioxide nano antibacterial particles/PVDF =0.5%, 0.825 g.
0.825g of porous copper-clad titanium dioxide nano antibacterial particles are ground and crushed, added into 97g of DMAc, and gradually added with 20g of PVDF after ultrasonic dispersion for 10 minutes, so that the viscosity of a high molecular polymer solution is gradually increased, and the nano particles are ensured not to be agglomerated after being uniformly dispersed.
And then gradually adding the PVDF solution prepared in the previous step into the prepared membrane casting solution (145 g of PVDF and 600g of DMAc), and strongly stirring for 10 hours to uniformly disperse the nano antibacterial particles into the membrane casting solution. And standing and defoaming for 8h in vacuum to obtain the stable porous copper-coated titanium dioxide nano antibacterial particle-composite antibacterial hollow fiber filter membrane casting solution.
3. Preparation of porous copper-clad titanium dioxide nano antibacterial particle composite antibacterial hollow fiber filter membrane
And (3) spinning the porous copper-coated titanium dioxide nano antibacterial particle-composite antibacterial hollow fiber filter membrane casting solution by adopting a conventional dry-wet method, wherein the inner and outer diameters of membrane filaments are 0.7/1.3mm, and washing the prepared membrane with purified water for 24 hours to be tested to obtain the porous copper-coated titanium dioxide nano antibacterial particle composite hollow fiber filter membrane.
Examples 0 and 2 to 7:
the same procedure as in example 1, except that the content of the porous copper-clad titanium dioxide nano antibacterial particles added to the casting solution was changed, and the ratio to PVDF was: 0%, 1.0%, 2.0%, 3.0%, 3.5%, 4.0%, 5.0%.
Comparative example:
the same procedure as in example 1, except that 3.5% (to PVDF) of common non-porous copper-coated titanium dioxide nano antibacterial particles were added to the casting solution.
As shown in fig. 2, fig. 4 and fig. 5, the porous copper-coated titanium dioxide nano antibacterial particle composite hollow fiber filter membrane prepared by the preparation method provided by the invention has a density asymmetric structure along the radial direction of the cross section, and comprises a hollow fiber filter membrane 2 formed by a dense layer 3 on the surface of the membrane and a microporous layer 4 on the inner surface, porous copper-coated titanium dioxide nano antibacterial particles 1 dispersed and embedded in the hollow fiber filter membrane 2, wherein the particles 1 are coated with copper particles, and a plurality of through holes 5 are formed therein for liquid permeation. The density of the porous copper-clad titanium dioxide nano antibacterial particles 1 contained in the compact layer 3 is greater than that of the porous copper-clad titanium dioxide nano antibacterial particles 1 contained in the microporous layer 4. Wherein the dense layer 3 of the membrane surface determines the separation performance and the microporous layer 4 of the inner face is a support layer, the thickness of the membrane being between 50 and 500 μm. The porous copper-coated titanium dioxide nano antibacterial particles 1 are uniformly dispersed in the hollow fiber filter membrane 2 and are enriched on the surface of the membrane. The micro-ingredients of the hollow fiber filter membrane can also be distributed at the edges of the through holes of the nano antibacterial particles 1 to strengthen the fixation of the nano antibacterial particles.
The pure water flux and the bubble point of the prepared hollow fiber filter membrane are detected by adopting a test method of a separation membrane aperture test method bubble point and average flow method GB/T112 + 2008 and a test method of a hollow fiber membrane microporous filter membrane HY/T051 + 1999. The antibacterial performance of the film is determined by using a standard experimental method for determining the antibacterial activity of the fixed antibacterial agent under the dynamic contact condition in ASTM E2149-2013 a. Table 1 shows the performance parameters of the porous copper-coated titanium dioxide nano antibacterial particle composite hollow fiber filter membranes prepared in examples 0-7.
TABLE 1
The hollow fiber filtration membranes were immersed in tap water, the immersion water was changed every day, and samples were taken every other month to test the antibacterial properties of the membrane surfaces, with the results shown in table 2. The result shows that the antibacterial effect of the porous antibacterial nano particle composite hollow fiber filter membrane changes little with time, mainly because the binding force between the porous nano particles and the membrane material is high, and the porous antibacterial nano particle composite hollow fiber filter membrane can not fall off and run off, so that the porous antibacterial nano particle composite hollow fiber filter membrane can keep good antibacterial performance. Table 2 shows the comparison of the long-term antibacterial properties of example 5 and the comparative examples
TABLE 2
Example 8:
step one is the same as embodiment 1;
step two: preparation of porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane casting solution
The formula of the casting solution is as follows: PS 19.3%, 193 g; DMF 72%, 720 g; PVP-K305.2%, 52 g; PEG 4003.5%, 35 g; porous nano antibacterial particles/PVDF =3.5%, 0.965 g.
6.755g of porous nano antibacterial particles are ground and crushed, then added into 220g of DMF, and after strong stirring for 60 minutes, PS 33g is gradually added to gradually increase the viscosity of the high molecular polymer solution and ensure that the nano particles are not agglomerated after being uniformly dispersed.
And then gradually adding the PS solution prepared in the previous step into the prepared casting solution (PS 160g, DMF500 g), and strongly stirring for 12h to uniformly disperse the nano antibacterial particles into the casting solution. Standing and defoaming for 10h in vacuum to obtain stable casting solution.
Step three: preparation of porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane
And (3) adopting a conventional dry-wet spinning method, wherein the inner diameter and the outer diameter of the membrane yarn are 0.6/1.2mm, and washing the prepared membrane with purified water for 24 hours to be tested.
Table 3 shows performance parameters of the hollow fiber filtration membrane of porous nano antibacterial particle composite PS prepared in example 8.
TABLE 3
The hollow fiber filtration membranes were immersed in tap water, the immersion water was changed every day, and samples were taken every other month to test the antibacterial properties of the membrane surfaces, with the results shown in table 4. The result shows that the antibacterial effect of the porous antibacterial nano particle composite PS hollow fiber filter membrane is little changed along with time, and the main reason is that the binding force of the porous nano particles and the membrane material is high, and the porous antibacterial nano particle composite PS hollow fiber filter membrane cannot fall off and run off, so that the porous antibacterial nano particle composite PS hollow fiber filter membrane can keep good antibacterial performance.
Table 4 shows the long-term antibacterial performance parameters of example 8
Example 9:
step one is the same as embodiment 1;
step two: preparation of porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane casting solution
The formula of the casting solution is as follows: PES 18.5%, 185 g; 70.5% of DMF, 705 g; PVP-K306.0%, 60 g; PEG4005.0%,50 g; porous nano antibacterial particles/PVDF =3.0%, 5.55 g.
Grinding and crushing 5.55g of porous nano antibacterial particles, adding the crushed particles into 205g of DMF, and after strongly stirring for 80 minutes, gradually adding 35g of PES to gradually increase the viscosity of the high molecular polymer solution so as to ensure that the nano particles are not agglomerated after being uniformly dispersed.
And then gradually adding the PES solution prepared in the previous step into the prepared membrane casting solution (PES 150g and DMF500 g), and strongly stirring for 13h to uniformly disperse the nano antibacterial particles into the membrane casting solution. Standing and defoaming for 12h in vacuum to obtain stable casting solution.
Step three: preparation of porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane
And (3) adopting a conventional dry-wet spinning method, wherein the inner diameter and the outer diameter of the membrane yarn are 0.8/1.5mm, and washing the prepared membrane with purified water for 24 hours to be tested.
Table 5 shows performance parameters of the porous nano antibacterial particle composite PES hollow fiber filtration membrane prepared in example 9.
TABLE 5
The hollow fiber filtration membranes were immersed in tap water, the immersion water was changed every day, and samples were taken every other month to test the antibacterial properties of the membrane surfaces, with the results shown in table 6. The result shows that the antibacterial effect of the porous antibacterial nanoparticle composite PES hollow fiber filter membrane is little changed along with time, and the main reason is that the binding force of the porous nanoparticles and the membrane material is high, and the porous antibacterial nanoparticle composite PES hollow fiber filter membrane cannot fall off and run off, so that the porous antibacterial nanoparticle composite PES hollow fiber filter membrane can keep good antibacterial performance.
Table 6 shows the long-term antibacterial properties of example 9
The porous copper-coated titanium dioxide nano antibacterial particles prepared by the method are coated with the metal copper particles on the surfaces, so that the titanium dioxide nano particles are endowed with more excellent antibacterial and anti-pollution performances, and the porous structures of the nano particles are kept to form a pure water channel. In addition, the copper is adopted to replace silver to wrap the nano particles, so that the cost of the nano antibacterial particles is reduced, and the ecological safety of the nano antibacterial material is improved. Porous copper-clad TiO with long-acting antibacterial effect2The nano antibacterial particle composite hollow fiber filter membrane is beneficial to embedding a membrane material into pores and enhancing the binding force between the nano particles and the membrane material due to the generation of pores inside porous nano particles, so that the nano particles cannot fall off and run off in the long-term use process, and the long-acting property of the nano antibacterial effect is ensured; on the other hand, the pores of the hollow fiber filter membrane are not blocked by the gaps of the nanoparticlesAnd water can permeate the membrane liquid material in the gaps, so that the flux of the membrane is not influenced. The composite hollow fiber filter membrane has the advantages that the flux and the retention rate are improved to a certain degree, the antibacterial performance of the surface of the membrane is greatly improved, the membrane pollution of the composite hollow fiber filter membrane can be delayed, and the use and maintenance cost of the composite hollow fiber filter membrane is favorably reduced.
The porous copper-clad titanium dioxide nano antibacterial particle composite hollow fiber filter membrane provided by the invention has the advantages of large water flux, high porosity, bacterial pollution resistance and easiness in cleaning, and can be widely applied to the fields of sewage and water treatment, pretreatment of material concentration, bitter brine and seawater desalination and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A preparation method of porous copper-clad titanium dioxide nano antibacterial particles comprises the following steps:
step 1: dripping titanium tetrachloride into an ice water bath, stirring, dripping aqueous solution of ammonium sulfate and concentrated hydrochloric acid, and stirring below a first set temperature to obtain a mixture;
step 2: heating the mixture to a second set temperature, preserving heat for 1h, adding concentrated ammonia water, adjusting the pH value to 5-7, cooling to room temperature, and standing for 12h to obtain titanium dioxide sol;
step 3, adding β -cyclodextrin into the titanium dioxide sol, stirring strongly, adjusting the pH value to 5-6, and continuing stirring for 1h to obtain a titanium dioxide glue solution;
and 4, step 4: putting the titanium dioxide glue solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 6-12h at 180 ℃ to obtain titanium dioxide nanoparticle sol;
and 5: adding CuCl2Adding sodium dodecyl benzene sulfonate into the titanium dioxide nano-particle sol, dispersing by ultrasonic wave,
after the pH value is adjusted to 5-7, adding a reducing agent formic acid and pure water, and uniformly mixing to prepare a reactant;
step 6: placing the reactant in ultraviolet light for light-induced reaction, and performing light reduction reaction on the surface of the titanium dioxide nano-particles to generate metal copper particles so as to prepare aqueous dispersion of the copper-coated titanium dioxide nano-particles;
and 7: and washing the aqueous dispersion of the copper-clad titanium dioxide nano-particles with pure water and ethanol, drying and calcining to prepare the porous copper-clad titanium dioxide nano-antibacterial particles.
2. The method of claim 1, wherein the first set point temperature is 15 ℃, the second set point temperature is 93 ℃ to 97 ℃, and the β -cyclodextrin added to the titanium dioxide sol is 15% to 110% by weight of the titanium tetrachloride.
3. The method of claim 1, wherein the ultrasonic dispersion time is 5-60 min; placing the reactant under ultraviolet light for 10-500 minutes to perform the photoinduction reaction; the calcination is carried out at 400-750 ℃.
4. The preparation method of claim 1, wherein the reactant is prepared from the following components in percentage by weight:
0.2-20% of titanium dioxide nano-particle sol; CuCl20.2-5%; 0.1 to 5 percent of sodium dodecyl benzene sulfonate;
formic acid: 0.5-7.5%; 79.2 to 99 percent of pure water.
5. A preparation method of a composite hollow fiber filter membrane with the porous copper-coated titanium dioxide nano antibacterial particles as claimed in any one of claims 1 to 4 comprises the following steps:
step 1: grinding and crushing the porous copper-clad titanium dioxide nano antibacterial particles, adding the crushed particles into a solvent, and adding a polymer while performing ultrasonic dispersion or strong stirring to gradually increase the viscosity of a polymer solution so that the porous copper-clad titanium dioxide nano antibacterial particles cannot be agglomerated after being uniformly dispersed;
step 2: gradually adding the polymer solution containing the porous copper-clad titanium dioxide nano antibacterial particles into a membrane casting solution, strongly stirring for 2-18h at 60-100 ℃ to uniformly disperse the porous copper-clad titanium dioxide nano antibacterial particles into the membrane casting solution, and defoaming in vacuum to prepare the porous copper-clad titanium dioxide nano antibacterial particle-polymer membrane casting solution;
and step 3: spinning the porous copper-clad titanium dioxide nano antibacterial particle-polymer casting solution by a conventional dry-wet method to obtain a hollow fiber filter membrane filament, and washing the prepared hollow fiber filter membrane filament with purified water for at least 24 hours to obtain the composite hollow fiber filter membrane of the porous copper-clad titanium dioxide nano antibacterial particle.
6. The preparation method according to claim 5, wherein the casting solution is a polymer solution prepared from a polymer, a pore-forming agent and a solvent, wherein the ratio of the polymer: the solvent is 10-40: 50-90.
7. The method of claim 5, wherein the polymer is at least one of polyvinylidene fluoride (PVDF), Polysulfone (PS), Polyethersulfone (PES), Polyacrylonitrile (PAN) or polyvinyl chloride (PVC); the solvent is at least one of N-N Dimethylformamide (DMF), N-N dimethylacetamide (DMAc), methyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP).
8. The preparation method according to claim 5, wherein the pore-forming agent is at least one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and LiCl, and the content of the pore-forming agent in the membrane casting solution is 0.2-20%.
9. The method according to claim 5, wherein the concentration of the polymer in the polymer solution is 10 to 40 wt%; the concentration of the porous copper-coated titanium dioxide nano antibacterial particles in the polymer solution relative to the polymer is 0.001-10 wt%.
10. A porous copper-coated titanium dioxide nano antibacterial particle composite hollow fiber filter membrane prepared by the preparation method of any one of claims 5 to 9, which is characterized by comprising a hollow fiber filter membrane formed by a dense layer on the surface of the membrane and a microporous layer on the inner surface, and porous copper-coated titanium dioxide nano antibacterial particles which are embedded in the hollow fiber filter membrane in a dispersing way; the density of the porous copper-clad titanium dioxide nano antibacterial particles contained in the compact layer is greater than that of the porous copper-clad titanium dioxide nano antibacterial particles contained in the microporous layer.
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