CN114345147A - Polydopamine and nanoparticle-coordinated modified PVDF (polyvinylidene fluoride) membrane and preparation method thereof - Google Patents
Polydopamine and nanoparticle-coordinated modified PVDF (polyvinylidene fluoride) membrane and preparation method thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 82
- 239000002033 PVDF binder Substances 0.000 title claims abstract description 64
- 229920001690 polydopamine Polymers 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title claims abstract description 33
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 60
- 239000002105 nanoparticle Substances 0.000 claims abstract description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 81
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 40
- 238000005266 casting Methods 0.000 claims description 32
- 238000003756 stirring Methods 0.000 claims description 26
- 239000007853 buffer solution Substances 0.000 claims description 20
- 239000011787 zinc oxide Substances 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 19
- 239000000395 magnesium oxide Substances 0.000 claims description 17
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 17
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 16
- 239000002253 acid Substances 0.000 claims description 16
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 14
- 238000000227 grinding Methods 0.000 claims description 13
- 239000003960 organic solvent Substances 0.000 claims description 11
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 11
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 11
- 239000000843 powder Substances 0.000 claims description 11
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 9
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 9
- 239000007983 Tris buffer Substances 0.000 claims description 8
- FYFFGSSZFBZTAH-UHFFFAOYSA-N methylaminomethanetriol Chemical compound CNC(O)(O)O FYFFGSSZFBZTAH-UHFFFAOYSA-N 0.000 claims description 8
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 8
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 7
- 229960003638 dopamine Drugs 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 239000003607 modifier Substances 0.000 claims description 6
- 238000005345 coagulation Methods 0.000 claims description 5
- 230000015271 coagulation Effects 0.000 claims description 5
- 239000004088 foaming agent Substances 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 4
- 238000007790 scraping Methods 0.000 claims description 4
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 claims description 4
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 claims description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
- 239000001863 hydroxypropyl cellulose Substances 0.000 claims description 3
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 claims description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- 229940069328 povidone Drugs 0.000 claims description 3
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 3
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical compound COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 claims description 3
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims description 2
- 239000005751 Copper oxide Substances 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 2
- 229910021607 Silver chloride Inorganic materials 0.000 claims description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 2
- 229910000431 copper oxide Inorganic materials 0.000 claims description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 2
- 239000002048 multi walled nanotube Substances 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 2
- 229910003445 palladium oxide Inorganic materials 0.000 claims description 2
- JQPTYAILLJKUCY-UHFFFAOYSA-N palladium(ii) oxide Chemical compound [O-2].[Pd+2] JQPTYAILLJKUCY-UHFFFAOYSA-N 0.000 claims description 2
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 2
- 229910001923 silver oxide Inorganic materials 0.000 claims description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 6
- 239000011148 porous material Substances 0.000 abstract description 4
- 238000000926 separation method Methods 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 abstract description 2
- 238000006386 neutralization reaction Methods 0.000 abstract description 2
- 239000010865 sewage Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 12
- 230000014759 maintenance of location Effects 0.000 description 10
- 230000004907 flux Effects 0.000 description 8
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 5
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 5
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 5
- 239000001099 ammonium carbonate Substances 0.000 description 5
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000000108 ultra-filtration Methods 0.000 description 3
- 108091003079 Bovine Serum Albumin Proteins 0.000 description 2
- 229940098773 bovine serum albumin Drugs 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004043 dyeing Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910001629 magnesium chloride Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- PGSADBUBUOPOJS-UHFFFAOYSA-N neutral red Chemical compound Cl.C1=C(C)C(N)=CC2=NC3=CC(N(C)C)=CC=C3N=C21 PGSADBUBUOPOJS-UHFFFAOYSA-N 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000000967 suction filtration Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000011592 zinc chloride Substances 0.000 description 2
- 235000005074 zinc chloride Nutrition 0.000 description 2
- INOIOAWTVPHTCJ-UHFFFAOYSA-N 6-acetamido-4-hydroxy-3-[[4-(2-sulfooxyethylsulfonyl)phenyl]diazenyl]naphthalene-2-sulfonic acid Chemical compound CC(=O)NC1=CC=C2C=C(C(N=NC3=CC=C(C=C3)S(=O)(=O)CCOS(O)(=O)=O)=C(O)C2=C1)S(O)(=O)=O INOIOAWTVPHTCJ-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
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- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
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Images
Abstract
The invention relates to the technical field of membrane separation materials, in particular to a preparation method of a polydopamine-coordinated nanoparticle-modified PVDF membrane. According to the invention, pure nanoparticles are doped on polydopamine by utilizing the adhesion effect of the polydopamine, and then the polydopamine doped with the nanoparticles is used for modifying the PVDF membrane, so that the nanoparticles can improve the pore structure of the PVDF membrane and improve the pollution resistance and mechanical strength of the PVDF membrane through the hydrophilicity of the surface of the polydopamine modified PVDF membrane, thereby realizing the good hydrophilicity and pollution resistance of the modified PVDF membrane. The PVDF modified membrane is adopted to treat sewage, so that membrane pollution and environmental pollution can be reduced, water resources are recycled, and the PVDF modified membrane has great significance in achieving carbon neutralization.
Description
Technical Field
The invention relates to the technical field of membrane separation materials, in particular to a polydopamine-coordinated nanoparticle-modified PVDF membrane and a preparation method thereof.
Background
Water shortages are considered one of the most serious problems in the 21 st century, and the contradiction between increasing water demand and decreasing water supply is particularly urgent. However, when water resources are in short supply, the water quality is continuously reduced due to various point source and non-point source pollution, the water environment pollution is aggravated, the available part of the water resources is reduced, and the difficulty of recycling is increased. This will seriously affect the sustainable development of the society and economy, and threaten the drinking water safety and health of people. Therefore, people are continuously urged to research a green water treatment method with excellent performance and lower cost.
The membrane separation technology has the advantages of energy conservation, low investment, simple and convenient operation, high treatment efficiency and the like, thereby being widely applied to the field of water purification. Among a plurality of membrane types, a polyvinylidene fluoride (PVDF) membrane is a newly developed special separation membrane, has the advantages of high mechanical strength, stable chemical property, strong oxidation resistance, radiation resistance, high temperature resistance and the like, and becomes one of the membrane types with the best comprehensive performance in the world at present.
In view of the above, in order to overcome the defects in the prior art, the present invention provides a method for preparing a PVDF film modified by polydopamine coordinated nanoparticles, so as to achieve good hydrophilicity and contamination resistance of the PVDF film.
Disclosure of Invention
(1) Technical problem to be solved
The invention aims to provide a preparation method of a PVDF membrane modified by polydopamine and nanoparticles, which modulates the structure and surface characteristics of a PVDF ultrafiltration membrane by combining polydopamine and nanoparticles and solves the problems of poor structure, low strength, non-hydrophilic membrane surface, low rejection rate and easy pollution of the PVDF membrane.
(2) Technical scheme
In order to solve the problems, the invention provides a preparation method of a PVDF membrane modified by polydopamine cooperative nanoparticles, which comprises the following steps:
preparing inorganic nano particles;
preparation of buffer solution: preparing a trihydroxymethyl aminomethane solution and a dilute acid solution respectively, and uniformly mixing the trihydroxymethyl aminomethane solution and the dilute acid solution to obtain a buffer solution;
preparation of the modified solution: adding inorganic nano-particles and dopamine into the buffer solution, and uniformly stirring to obtain a modified solution;
preparation of the modifier: grinding the solid obtained after drying the modified solution to obtain polydopamine powder doped with nano particles;
preparing a casting solution: dissolving polyvinylidene fluoride and a pore-foaming agent in an organic solvent, uniformly stirring, then adding a set amount of polydopamine powder doped with nano particles, heating and uniformly stirring to obtain a membrane casting solution;
and preparing the modified membrane by utilizing the membrane casting solution.
Further, the inorganic nanoparticles are one or more of zinc oxide, magnesium oxide, titanium oxide, zirconium oxide, silicon oxide, aluminum oxide, copper oxide, silver oxide, palladium oxide, silver protoxide, silver chloride, barium sulfate, ferric oxide, ferroferric oxide, sulfonated graphene, calcium carbonate and multi-walled carbon nanotubes, the particle size of the nanoparticles is 1-200 nm, and the purity of the nanoparticles is analytically pure.
Further, when the buffer solution is prepared, the pH value of the buffer solution is 7.5-9.5.
Furthermore, the concentration of the tris solution is 0.01-0.2 mol/L, the dilute acid is one of acetic acid, hydrochloric acid and nitric acid, the concentration of the dilute acid is 0.01-0.2 mol/L, and the volume ratio of the tris solution to the dilute acid is 50-100: 15-20.
Further, when the modifier is prepared, the drying temperature of the solution is 50-80 ℃, the drying time is 8-24 hours, the device used for grinding is a ball mill, and the grinding time is 20-60 min.
Further, when the membrane casting solution is prepared, the mass fraction of the polydopamine powder doped with the nano particles is 0.1-5%, and the mass ratio of the polyvinylidene fluoride to the pore-forming agent to the organic solvent is 14-18: 1-5: 81-85, wherein the stirring speed is 100-300 r/min, and the stirring time is 2-8 h.
Further, the pore-forming agent is one or more of hydroxypropyl cellulose, povidone, polyvinylpyrrolidone copolymer, lithium chloride, polyvinylpyrrolidone and polyvinyl alcohol, and the organic solvent is one of N, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, triethyl phosphate and trimethyl phosphate.
Further, when the modified membrane is prepared by using the membrane casting solution, the membrane casting solution is heated and uniformly stirred and then subjected to membrane scraping treatment to obtain the modified membrane.
Further, the heating mode is water bath heating, the heating temperature is 50-80 ℃, the heating time is 12-24 hours, during film making, the film casting solution is used for film making through a film making machine, and then the obtained film is placed in a water coagulation bath after being stopped in the air for 30-60 s.
The invention also provides a modified PVDF membrane prepared by the preparation method in the scheme.
(3) Advantageous effects
In conclusion, the pure nanoparticles are doped on the polydopamine by utilizing the adhesion effect of the polydopamine through the hydrophilicity of the surface of the polydopamine modified PVDF membrane, and the polydopamine doped with the nanoparticles is used for modifying the PVDF membrane.
The invention combines the characteristics of organic and inorganic substances, modulates the structure and surface characteristics of the PVDF ultrafiltration membrane, and combines the dual advantages of polydopamine and nanoparticles: the nano particles can improve the pore structure, the anti-pollution capacity and the mechanical strength of the membrane are obviously improved, and the polypolyamine can improve the hydrophilicity of the surface of the PVDF membrane; the defect of single use of the nano-particles is overcome, the structure of the membrane pores is effectively improved, meanwhile, the inorganic pure nano-particles doped in the membrane pores can be used for inhibiting the biological pollution on the surface of the membrane, and the preparation method is simple and controllable.
With the rapid development of the printing and dyeing industry, the PVDF modified membrane is used for printing and dyeing wastewater treatment, membrane pollution and environmental pollution can be reduced, and water resources are recycled, which has great significance for achieving carbon neutralization.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram showing the comparison of water flux of a modified PVDF film at 25 ℃ and 0.1MPa under different polydopamine-doped nano ZnO contents.
FIG. 2 is a graph showing the retention rate of PVDF films modified at different polydopamine-doped nano ZnO contents at 25 ℃ and 0.1MPa compared with that of different pollutants.
Fig. 3 is a comparative schematic diagram of the mechanical strength of modified PVDF films at different polydopamine doped nano ZnO contents.
FIG. 4 is a schematic diagram showing the comparison of water flux of modified PVDF membrane at 25 ℃ and 0.1MPa under different polydopamine-doped nanometer MgO contents.
FIG. 5 is a graph showing the retention of different contaminants compared to PVDF modified at different polydopamine-doped nano-MgO contents at 25 ℃ and 0.1 MPa.
Fig. 6 is a comparative graph of the mechanical strength of modified PVDF membranes at different polydopamine doped nano-MgO contents.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the described embodiments.
The embodiment of the invention discloses a preparation method of a polydopamine-coordinated nanoparticle-modified PVDF (polyvinylidene fluoride) membrane, which comprises the following steps:
preparing inorganic nano particles;
preparation of buffer solution: preparing a trihydroxymethyl aminomethane solution and a dilute acid solution respectively, and uniformly mixing the trihydroxymethyl aminomethane solution and the dilute acid solution to obtain a buffer solution;
preparation of the modified solution: adding inorganic nano-particles and dopamine into the buffer solution, and uniformly stirring to obtain a modified solution;
preparation of the modifier: grinding the solid obtained after drying the modified solution to obtain polydopamine powder doped with nano particles;
preparing a casting solution: dissolving polyvinylidene fluoride and a pore-foaming agent in an organic solvent, uniformly stirring, then adding a certain amount of polydopamine powder doped with nano particles, heating and uniformly stirring to obtain a membrane casting solution;
and preparing the modified membrane by utilizing the membrane casting solution.
Specifically, when the inorganic nanoparticles are prepared, inorganic salts are dissolved in deionized water, ammonium bicarbonate is dissolved in the deionized water, dilute acid is dripped to adjust the pH value to be alkaline, precipitates obtained through reaction are subjected to suction filtration, washed and dried by sodium bicarbonate solution, and calcined and ground to obtain the ultrapure nanoparticles. Preferably, the particle size of the nano particles is 1-200 nm, and the nano particles are zinc oxide or magnesium oxide.
Specifically, when the buffer solution is prepared, the pH value of the buffer solution is adjusted to 7.5-9.5. Preferably, the concentration of the tris solution is 0.01-0.2 mol/L, the acid is one of acetic acid, hydrochloric acid and nitric acid, and the volume ratio of the tris solution to the dilute acid is 50-100: 15-20, wherein the concentration of the dilute acid is 0.01-0.2 mol/L.
Specifically, when the modified solution is prepared, dopamine and nanoparticles are added into the buffer solution in a mass ratio, and preferably, the mass ratio of dopamine to nanoparticles is 1: 1.
Specifically, when the modifier is prepared, the drying temperature of the modified solution is 50-80 ℃, the drying time is 8-24 h, the device used for grinding is a ball mill, preferably, the ball mill is a planetary ball mill filled with 45% steel balls, and the grinding time is 20-60 min, more preferably, 20 min.
Specifically, when the casting solution is prepared, the mass ratio of polyvinylidene fluoride to pore-foaming agent to organic solvent is 14-18: 1-5: 81-85, preferably, the mass ratio of the polyvinylidene fluoride to the pore-forming agent to the organic solvent is 15:1:84, the stirring speed is 100-300 r/min, and the stirring time is 2-8 h.
Preferably, the pore-forming agent is one or more of hydroxypropyl cellulose, povidone, polyvinylpyrrolidone copolymer, lithium chloride, polyvinylpyrrolidone and polyvinyl alcohol, and the organic solvent is one of N, N dimethylformamide, N dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, triethyl phosphate and trimethyl phosphate.
Specifically, when the modified membrane is prepared by using the membrane casting solution, the membrane casting solution is heated and stirred uniformly to prepare the modified membrane. Preferably, the heating mode is water bath heating, the heating temperature is 50-80 ℃, the heating time is 12-24 hours, during film making, the film casting solution is used for film making by a film making machine, and then the obtained film is placed in a water coagulation bath after being stopped in the air for 30-60 s.
Specifically, when the casting solution is prepared, the mass fraction of the polydopamine powder doped with the nanoparticles is 0.1-5%.
Example 1
A preparation method of a polydopamine and nano zinc oxide modified PVDF membrane comprises the following specific steps:
1) weighing 20g of zinc chloride, dissolving the zinc chloride in 250mL of deionized water, weighing 10g of ammonium bicarbonate, dissolving the ammonium bicarbonate in the deionized water, dropwise adding dilute hydrochloric acid to adjust the pH to about 9, filtering a white precipitate obtained by the reaction, washing the white precipitate with 0.2% sodium bicarbonate solution, drying the white precipitate, calcining and grinding the white precipitate in a muffle furnace to obtain the ultrapure nano zinc oxide, wherein the calcining temperature of the muffle furnace is 600 ℃, the heating rate is 1 ℃ and min-1The calcination time is 4 h.
2) Preparing 0.01mol/L trihydroxymethyl aminomethane solution;
3) preparing 0.01mol/L hydrochloric acid solution;
4) mixing the tris solution obtained in the step 2 and the hydrochloric acid solution obtained in the step 3 to obtain a buffer solution, and adjusting the pH to 7.5 by a pH meter;
5) adding a buffer solution into the mixture according to the mass ratio of 1:1, uniformly mixing the dopamine and the nano ZnO, and stirring for 24 hours at a stirring speed of 100 r/min;
6) pouring the polydopamine solution doped with nano ZnO obtained in the step (5) into a glass ware, drying at 50 ℃ for 16h, and grinding the solid obtained after drying in a planetary ball mill with a steel ball filling rate of 45% for 20min to obtain polydopamine powder doped with nano ZnO;
7) polyvinylidene fluoride, lithium chloride and N, N-dimethylacetamide according to a mass ratio of 15:1:84 preparing a solution, stirring for 8 hours at the speed of 100r/min, and adding 2% by mass of polydopamine doped with nano ZnO to obtain a casting solution.
8) And (3) heating and stirring the casting solution obtained in the step (7) at the water bath temperature of 50 ℃ for 24h to obtain a casting solution with uniform phases, placing the casting solution on a flat plate, scraping the film by using a film scraper, pausing the film in the air for 30s, and immediately placing the film into a water coagulation bath to obtain the PVDF modified film.
Fig. 1 is a schematic diagram comparing water flux of the modified PVDF film at 25 ℃ and 0.1MPa under different polydopamine-doped nano ZnO contents, and it can be seen from the schematic diagram that, as the polydopamine-doped nano ZnO content increases, the pure water flux of the modified PVDF film increases and then slightly decreases, and reaches a maximum value when the mass fraction of the polydopamine-doped nano ZnO is 1.2%, and the water flux is increased by one time compared with that of the pure film.
Fig. 2 is a schematic diagram showing the retention rates of different pollutants of modified PVDF membranes with different polydopamine-doped nano ZnO contents at 25 ℃ and 0.1MPa, and it can be seen that the modified PVDF membrane has the best retention effect on bovine serum albumin, up to 95.2%, has a better retention effect on neutral red and disperse deep blue HGL, and can reach more than 90%, and the retention rate on reactive orange KNG is also more than 70%.
Fig. 3 is a schematic diagram comparing mechanical strength of the modified PVDF film with different polydopamine-doped nano ZnO contents, and it can be seen from the diagram that as the mass fraction of the polydopamine-doped nano ZnO increases, the mechanical strength of the PVDF film increases significantly, and reaches 4.68MPa at most, and compared with a pure film, the mechanical strength is improved by 47.6%.
Example 2
step 7), polyvinylidene fluoride, polyvinylpyrrolidone and N, N-dimethylacetamide are mixed according to the mass ratio of 15:1:84 preparing a solution, stirring for 4 hours at the speed of 200r/min, and adding 1% by mass of polydopamine doped with nano ZnO to obtain a casting solution.
Example 3
1) Weighing 20g of magnesium chloride, dissolving the magnesium chloride in 250mL of deionized water, weighing 10g of ammonium bicarbonate, dissolving the ammonium bicarbonate in the deionized water, dropwise adding dilute hydrochloric acid to adjust the pH to about 9, carrying out suction filtration on a white precipitate obtained by reaction, washing with 0.2% sodium bicarbonate solution, drying, calcining and grinding in a muffle furnace to obtain the ultrapure nano zinc oxide, wherein the calcining temperature of the muffle furnace is 800 ℃, the heating rate is 1 ℃ and min < -1 >, and the calcining time is 2 hours.
2) Preparing 0.1mol/L trihydroxymethyl aminomethane solution;
3) preparing 0.1mol/L hydrochloric acid solution;
4) mixing the tris solution obtained in the step 2 and the hydrochloric acid solution obtained in the step 3 to obtain a buffer solution, and adjusting the pH to 8.5 by a pH meter;
5) adding a buffer solution into the mixture according to the mass ratio of 1:1, uniformly mixing the dopamine and the nano MgO, and stirring for 18 hours at a stirring speed of 200 r/min;
6) pouring the polydopamine solution doped with the nano MgO obtained in the step (5) into a glass ware, drying at 70 ℃ for 16h, and grinding the dried solid in a planetary ball mill with a steel ball filling rate of 45% for 20min to obtain polydopamine powder doped with the nano MgO;
7) polyvinylidene fluoride, lithium chloride and N, N-dimethylacetamide according to a mass ratio of 15:1:84 preparing a solution, stirring for 3 hours at the speed of 200r/min, and adding 2% of polydopamine doped with nano MgO by mass fraction to obtain a membrane casting solution.
8) And (3) heating and stirring the casting solution obtained in the step (7) at the water bath temperature of 80 ℃ for 12h to obtain a casting solution with uniform phases, placing the casting solution on a flat plate, scraping the film by using a film scraper, pausing the film in the air for 45s, and immediately placing the film into a water coagulation bath to obtain the PVDF modified film.
Fig. 4 is a schematic diagram comparing water flux of the modified PVDF membrane at 25 ℃ and 0.1MPa under different polydopamine-doped nano-MgO contents, and it can be seen from the comparison result that, as the polydopamine-doped nano-MgO content increases, the pure water flux of the modified PVDF membrane increases and then slightly decreases, and reaches a maximum value when the mass fraction of the polydopamine-doped nano-MgO is 1.2%, and the water flux is increased by one time compared with that of the pure membrane.
FIG. 5 is a schematic diagram showing the retention rates of MgO modified PVDF membranes at 25 ℃ and 0.1MPa for different pollutants under different polydopamine-doped nano contents, from which it can be seen that the retention rate of the modified PVDF membranes for disperse deep blue HGL reaches 91%, the retention effect for neutral red and bovine serum albumin is better, and the retention rate is greatly improved compared with that of pure membranes.
Fig. 6 is a comparison schematic diagram of the mechanical strength of the modified PVDF film under different polydopamine-doped nano-MgO contents, and it can be seen from the diagram that as the mass fraction of polydopamine-doped nano-MgO increases, the mechanical strength of the PVDF film increases significantly, and reaches up to 5.32MPa, and compared with a pure film, the mechanical strength increases by 67.8%.
Example 4
step 7), polyvinylidene fluoride, polyvinylpyrrolidone and N, N-dimethylacetamide are mixed according to the mass ratio of 15:1:84 preparing a solution, stirring for 2 hours at the speed of 300r/min, and adding 1% of polydopamine doped with nano MgO by mass fraction to obtain a casting solution.
In conclusion, in the preparation method of the modified PVDF membrane provided by the invention, the structure and the surface characteristics of the PVDF ultrafiltration membrane are modulated by combining polydopamine and nano particles, so that the good hydrophilicity and the pollution resistance of the PVDF membrane are realized.
It is to be understood that the invention is not limited to the specific steps and structures described above and shown in the attached drawings. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
The above description is only an example of the present application and is not limited to the present application. Various modifications and alterations to this application will become apparent to those skilled in the art without departing from the scope of this invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A preparation method of a polydopamine-coordinated nanoparticle-modified PVDF (polyvinylidene fluoride) membrane is characterized by comprising the following steps:
preparing inorganic nano particles;
preparation of buffer solution: preparing a trihydroxymethyl aminomethane solution and a dilute acid solution respectively, and uniformly mixing the trihydroxymethyl aminomethane solution and the dilute acid solution to obtain a buffer solution;
preparation of the modified solution: adding inorganic nano-particles and dopamine into the buffer solution, and uniformly stirring to obtain a modified solution;
preparation of the modifier: grinding the solid obtained after drying the modified solution to obtain polydopamine powder doped with nano particles;
preparing a casting solution: dissolving polyvinylidene fluoride and a pore-foaming agent in an organic solvent, uniformly stirring, then adding a set amount of polydopamine powder doped with nano particles, heating and uniformly stirring to obtain a membrane casting solution;
and preparing the modified membrane by utilizing the membrane casting solution.
2. The preparation method according to claim 1, wherein the inorganic nanoparticles are one or more of zinc oxide, magnesium oxide, titanium oxide, zirconium oxide, silicon oxide, aluminum oxide, copper oxide, silver oxide, palladium oxide, silver protoxide, silver chloride, barium sulfate, iron oxide, ferroferric oxide, sulfonated graphene, calcium carbonate and multi-walled carbon nanotubes, the particle size of the nanoparticles is 1-200 nm, and the purity of the nanoparticles is analytical grade.
3. The method according to claim 1, wherein the buffer solution is prepared by adjusting the pH of the buffer solution to 7.5 to 9.5.
4. The method according to claim 2, wherein the concentration of the tris solution is 0.01 to 0.2mol/L, the acid is one of acetic acid, hydrochloric acid and nitric acid, the concentration of the acid is 0.01 to 0.2mol/L, and the volume ratio of the tris solution to the acid is 50 to 100:15 to 20.
5. The preparation method according to claim 1, wherein the drying temperature of the solution is 50-80 ℃ and the drying time is 8-24 h during the preparation of the modifier, the device used for grinding is a ball mill, and the grinding time is 20-60 min.
6. The preparation method according to claim 1, wherein in the preparation of the casting solution, the mass fraction of the polydopamine powder doped with the nanoparticles is 0.1-5%, and the mass ratio of the polyvinylidene fluoride to the pore-forming agent to the organic solvent is 14-18: 1-5: 81-85, stirring speed is 100-300 r/min when polyvinylidene fluoride and pore-foaming agent are dissolved in organic solvent, and stirring time is 2-8 h.
7. The preparation method according to claim 6, wherein the pore-forming agent is one or more of hydroxypropyl cellulose, povidone, polyvinylpyrrolidone copolymer, lithium chloride, polyvinylpyrrolidone, and polyvinyl alcohol, and the organic solvent is one of N, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, triethyl phosphate, and trimethyl phosphate.
8. The preparation method according to claim 1, wherein when the modified membrane is prepared from the membrane casting solution, the membrane casting solution is heated and stirred uniformly, and then subjected to membrane scraping treatment to obtain the modified membrane.
9. The preparation method according to claim 8, wherein the heating mode is water bath heating, the heating temperature is 50-80 ℃, the heating time is 12-24 h, the stirring speed is 100-300 r/min, the membrane casting solution is used for membrane preparation by a membrane preparation machine during membrane preparation, and then the obtained membrane is stopped in air for 30-60 s and then put into a water coagulation bath.
10. A polydopamine-nanoparticle-synergistically-modified PVDF membrane is characterized in that: which is prepared by the preparation method of any one of claims 1 to 9.
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| CN117431587A (en) * | 2023-12-22 | 2024-01-23 | 烟台泰和新材高分子新材料研究院有限公司 | Composite diaphragm and preparation method and application thereof |
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