CN112679221B - Method for preparing zirconium dioxide hollow film by microfluidics - Google Patents
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Abstract
A method for preparing a zirconium dioxide hollow film by microfluidics is characterized by comprising the following steps: the method comprises the following steps: the material is first prepared, i.e. prepared for manufacturingPreparation of ZrO2Raw material of ceramic film, and then preparing ZrO by using microfluidic system2Gel film, ZrO obtained2And sintering the gel film by a ceramic film to obtain a target product. The application has the advantages that the microporous structure can be applied to the fields of filtration, purification and the like, the thickness of the film is uniform, and the peeling with the substrate is easy.
Description
Technical Field
The application relates to the technical field of ceramic film preparation, in particular to a method for preparing a zirconium dioxide hollow film by microfluidics.
Background
ZrO2The ceramic film is a ceramic material with excellent thermal, chemical and mechanical stability, low friction coefficient and good wear resistance. At present, the main preparation process technologies of the zirconia ceramic film comprise sputtering deposition, vapor deposition, a sol-gel method, plasma spraying and the like. However, the above method may have the problems of rough surface, inconsistent thickness, poor stability or high cost, long preparation time, being not beneficial to industrial production, etc. in the preparation process. ZrO (ZrO)2Ceramic films are expected to be used as wear resistant or protective coatings in harsh environments and therefore on ZrO2The study of thin films has attracted much attention from various researchers. Preparation of ZrO, as in application CN1635064A2A ZrO composite lubricating film is introduced in its preparing process2A method for preparing a ceramic film by: heating and dissolving zirconium inorganic salt and a stable complexing agent in absolute ethyl alcohol, wherein the stable complexing agent is acetylacetone or citric acid, adjusting the pH value to 1-3 with acid, adding organic film-forming aid polyvinyl alcohol or polyethylene glycol, and aging the obtained solution in a water bath for 24-96 hours to obtain clear and transparent zirconium oxide-based precursor sol; preparing a sol film on a substrate by using a clean glass slide, a monocrystalline silicon wafer, an aluminum sheet or a stainless steel sheet as a substrate and using a dipping-pulling method to prepare the sol film on the substrate, wherein the film preparation temperature is 15-25 ℃, the relative humidity is 40-50%, and the pulling speed is controlled within the range of 10-90 cm/min to obtain a uniform sol film; drying the sol film in the air at 20-70 ℃, then heating to 500-550 ℃, preserving heat for 20-30 minutes, and finally naturally cooling to room temperature to obtain the sol filmTo obtain the required ZrO2A ceramic film; ZrO obtained in this manner2The ceramic film is a monolithic film without pore diameters, can be used only in the wear-resistant or protective coating described in the above documents, and cannot be applied to the fields of filtration, purification and the like, so that the application field is limited; moreover, the method adopts the dipping-pulling method to prepare the film, which can cause the defects of uneven film thickness, difficult substrate peeling and the like.
In recent years, Microfluidics (Microfluidics) refers to science and technology involved in systems that use microchannels (tens to hundreds of microns in size) to process or manipulate tiny fluids (nanoliters to attoliters), and is an emerging interdiscipline that involves chemistry, fluid physics, microelectronics, new materials, biology, and biomedical engineering. Because of their miniaturization, integration, etc., microfluidic devices are commonly referred to as microfluidic chips, also known as Lab-on-a-chips (Lab-on-a-chips) and micro-Total Analytical systems (micro-Total Analytical systems). The early concept of microfluidics can be traced back to gas chromatographs fabricated on silicon wafers by photolithography in the 70 s of the 19 th century, and then developed into microfluidic capillary electrophoresis instruments, microreactors and the like. One of the important features of microfluidics is the unique fluid properties in microscale environments, such as laminar flow and droplets. With these unique fluidic phenomena, microfluidics can achieve a range of microfabrication and micromanipulation that are difficult to accomplish with conventional methods. Microfluidics is currently considered to have great development potential and broad application prospects in biomedical research.
How to prepare ZrO by a microfluidic method2Ceramic films have not been reported.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a micro-fluidic method for preparing ZrO, which has a microporous structure, can be applied to the fields of filtration, purification and the like, has uniform film thickness and is easy to peel from a substrate2A method of forming a ceramic film.
In order to solve the technical problems, the invention adopts the technical scheme that: method for preparing zirconium dioxide hollow film by microfluidics, and methodComprises the following steps: firstly, the material preparation is carried out, namely, the material preparation is prepared for preparing ZrO2Preparing a gel membrane from the raw material of the ceramic membrane through a microfluidic system, and sintering the obtained gel membrane by using a ceramic membrane to obtain a target product.
Preferably, the material preparation comprises: the external phase is a mixed solution of silicone oil, surfactant span 80 and tetramethyl diethylamine; intermediate phase: adding a pH probe-carboxyl fluorescein into a zirconium sol precursor; wherein, the zirconium gel precursor is formed by firstly mixing zirconium oxychloride aqueous solution, urea, citric acid and polyethylene, then adding yttrium nitrate, heating, stirring and uniformly mixing; internal phase: molten paraffin (melting point 27 ℃, 50 ℃);
preferably, the preparation of the gel film specifically comprises the following steps:
introducing a material into a channel of a microfluidic system by using an injection pump, wherein the microfluidic system comprises a first microchannel, a second microchannel and a third microchannel which are positioned on a microfluidic mainboard, the first microchannel is positioned in the middle of the microfluidic mainboard and extends along the length direction, one end of the first microchannel is a medium feeding end, and the other end of the first microchannel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second microchannel and the third microchannel are gathered in the first microchannel and output from the media output end;
then inputting the internal phase into a first micro-channel of a micro-fluidic system through a medium feeding end, inputting the intermediate phase into a second micro-channel, and inputting the external phase into a third micro-channel;
then collecting the gel film which passes through the microfluidic system and is subjected to gelation in a container containing an external phase solution, and soaking the film to fully complete the gelation process; and then heating or soaking the gel membrane in a normal octane solution to remove paraffin to form a hollow membrane, cleaning and drying the hollow membrane by using deionized water, and sintering the ceramic membrane to obtain a final target product.
Preferably, the ceramic film is sintered, specifically: sequentially washing the gel membrane by using trichloroethylene, 1wt% of Triton X-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film at room temperature; then gradually heating the gel film to 1400-1600 ℃ for 35-55 hours to sinter until a ceramic film is formed, then transferring the film to a crucible, and respectively maintaining the calcination time of 200-260 minutes in the three temperature ranges of 180-220 ℃, 280-320 ℃ and 580-620 ℃; then the temperature is gradually raised to 1000-1200 ℃ and 1450-1550 ℃ and is kept for 260 minutes respectively, so that the zirconia crystal phase is converted from monoclinic to tetragonal, and then the ceramic membrane is cooled to the room temperature.
Preferably, the concentration of the surfactant span 80 in the mixed solution is 1wt%, and the concentration of the tetramethyldiethylamine in the mixed solution is 0.125 vol%.
Preferably, zirconium oxychloride (ZrOCl) as described herein2) Urea (CON) with an aqueous solution concentration of 1.5-3mol/L2H4) 3-5mol/L, citric acid (C)6H8O) is 0.4-1mol/L, 6-12 wt% of Polyethylene (PVA), and the volume ratio of the four components is 2:3:0.8: 1.5. (the content ranges of these four components are the respective content concentrations adjusted and then mixed, and are all considered to be the concentrations in water, that is, the concentrations prepared using water as a solvent, without any specific description).
Further preferably, the zirconium gel precursor described herein is prepared from 2mol/L zirconium oxychloride (ZrOCl)2) Aqueous solution, 4mol/L Urea (CON)2H4) 0.5mol/L citric acid (C)6H8O)8 wt% Polyethylene (PVA).
Preferably, the pH probe-carboxyfluorescein described herein is 2',7' -bis (2-carboxylethyl) -5(6) -carboxyfluorescein, which corresponds to CAS No. 85138-49-4.
Preferably, the yttrium nitrate (Y (NO) described herein3)3·6H2O) is added in an amount of 1-3g, and the mixture is heated to 85-95 ℃ and then stirred slowly to 15-30 ml.
Preferably, the inner pore size of the first microchannel is 40-300 microns, the inner pore size of the second microchannel is 400-500 microns, and the inner pore size of the third microchannel is 600-800 microns.
Preferably, the number of the second micro-channels is at least one: preferably, the number of the second microchannels is two, and the two second microchannels are vertically connected with the first microchannel and symmetrically distributed on two sides of the first microchannel.
Preferably, the number of the third micro-channels is at least one: further preferably, the number of the third microchannels is two, and the two third microchannels are vertically connected with the first microchannel and symmetrically distributed on two sides of the first microchannel.
Preferably, the medium flow of the first microchannel is 50-80 muL/min, the medium flow of the second microchannel is 30-50 muL/min, and the medium flow of the third microchannel is 80-150 muL/min;
preferably, the gelated gel film is immersed in a container containing an external phase solution and left standing for 20 to 30 hours to fully complete the gelation process; then heating the gel film to 60-80 ℃ or soaking the gel film in n-octane solution for 20-30 hours to remove paraffin to form a hollow film.
ZrO prepared by this specific process of the present invention2The ceramic film has the following advantages and advantages:
1. according to the method for preparing the film by the micro-fluidic method, the micro-channels with different sizes or the flow velocity of each channel can be adjusted to control the mixing and distribution of each medium in the channel, so that the advantages of accurately controlling the thickness and the components of the film can be achieved, the thickness of the film is more uniform, and the method has the advantages of material saving, high synthesis efficiency and the like due to the natural advantages of the micro-size.
2. The invention adopts liquid paraffin as a medium for the first time, brings various components into a microfluidic system, and then evaporates and removes the paraffin, so that a plurality of small holes can be uniformly obtained on the obtained ceramic film, and guarantees are provided for the ceramic film in the field of filtration or purification. And the paraffin and the micro-fluidic system are combined with each other to prepare ZrO2The ceramic film technology is also reported for the first time, and more importantly, the paraffin and other components can be fully mixed and dispersed, are easier to control, and drive other components to run more stably and more uniformlyThe uniformity is increased, and the generation of pores of the obtained target product is more uniform.
3. The application prepares ZrO for the first time in a micro-fluidic mode2The ceramic film prepared by the method has the following advantages: the cost is low, and the method has the potential of industrial production; the components are controllable, for example, films with different thicknesses can be obtained by adjusting the flow rate of the medium in each micro-channel; ZrO with different concentrations can be obtained by adjusting the composition of the medium in each microchannel2The film of (2), and the like. In addition, the ceramic membrane obtained by the thin membrane through the high temperature twice after the low temperature calcination in three temperature sections and the high temperature twice after the high temperature sintering is performed after the thin membrane passes through the microfluidic system, has the advantages of high temperature resistance, corrosion resistance, good mechanical property and the like; in addition, the internal diameter of each passageway and the medium velocity of flow that corresponds all have reasonable control parameter in this application micro-fluidic, also make or final product do not exist because of the crystallization takes place the phenomenon of solid-liquid phase separation, also make final product have thickness even, the equipartition aperture above, can adapt to the operation requirement in filtration or purification field.
4. The purpose of adding the pH probe is to monitor the pH value of the intermediate phase solution, so that the reaction condition is accurately controlled; in addition, adopt bilateral symmetry to set up the microchannel simultaneously among this application preferred scheme and come the feeding, can realize controlling the simultaneous feeding, guarantee the stability of medium in the passageway, guarantee the thickness uniformity of thin film structure.
5. According to the scheme, three phases are divided into three microfluidic channels to enter the system, so that the flow speed and the reaction condition of each phase can be flexibly controlled, and the film forming condition can be accurately controlled, so that the finally obtained material has more uniform thickness and more excellent performance.
6. The micro-fluidic system can generate two or more hollow membranes simultaneously by one set of micro-fluidic system through controlling the length of the pipeline and the initial flow velocity, and greatly improves the production efficiency.
Drawings
FIG. 1 preparation of ZrO in accordance with the present application2The pipeline structure of the hollow film microfluidic system is schematically shown.
FIG. 2 preparation of ZrO by microfluidic method of the present application2Schematic flow structure of the hollow film method.
FIG. 3 preparation of ZrO by microfluidic method of the present application2Simulated preparation of hollow membranes.
As shown in the attached drawings: 1. first microchannel (for medium inflow of the internal phase and outflow after mixing of the three phases), 2. second microchannel (for medium inflow of the intermediate phase), 3. third microchannel (for medium inflow of the external phase).
Detailed Description
The present invention will be described in further detail below with reference to specific embodiments and drawings, but the present invention is not limited to the following embodiments.
The micro-fluidic system adopts the structure shown in the attached figures 1-2, and comprises a first micro-channel 1, a second micro-channel 2 and a third micro-channel 3 which are positioned on a micro-fluidic main board, wherein the first micro-channel is positioned in the middle of the micro-fluidic main board and extends along the length direction, one end of the first micro-channel is a medium feeding end, and the other end of the first micro-channel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second micro-channel and the third micro-channel are gathered in the first micro-channel and output from the media output end; in the embodiment of the application, two second microchannels and two third microchannels are respectively arranged, are respectively symmetrically arranged on two sides of the first microchannel and are vertical to the first microchannel; the curved pipe in fig. 2 is a pipe for feeding, which facilitates feeding.
Before entering the first microchannel, the second microchannel 2 in fig. 2 may be provided with a section of pipe parallel to the first microchannel, and then enter a section of second microchannel perpendicular to the first microchannel, which may extend the channel distance and control the flow rate entering the first microchannel more smoothly; the flow velocity of three phases of different media is taken into consideration simultaneously, the meeting time and the corresponding flow velocity of the three are ensured so as to realize the most ideal hollow membrane material, wherein the inner phase is paraffin in a molten state, the intermediate phase is equivalent to oil, the outer phase is equivalent to water, and the target product can be obtained only by reasonably controlling the speed, the flow velocity, the feeding position and the like of the three.
As shown in fig. 3, a simulated preparation diagram of a ZrO2 ceramic film prepared by the microfluidic method of the present application is shown, wherein the specific color change of Phase3 represents the change of the percentage of different phases, wherein red is a paraffin Phase (the color of the top of Phase 3), blue is an aqueous Phase (the color of the bottom of Phase 3), and green is an oil Phase (the color of the middle of Phase 3); y represents the length of the micro-channel (unit is m), Z represents the specific position of the micro-channel, and the accompanying drawings (black and white figures, based on the drawings published by the application) can see that the hollow film is formed by the application along with the change of the proportion of each phase and the mutual reaction and fusion of the phase and the phase.
Example 1
The method comprises the following steps:
(1) material preparation
The external phase is prepared by adding 0.25 vol% of Tetramethyldiethylamine (TMEDA) into silicone oil, wherein the surfactant is span 80(1.5 wt%); both span 80 and tetramethyldiethylamine are at final concentrations in silicone oil;
intermediate phase zirconium sol precursor: the zirconium gel precursor is prepared from 2.5mol/L zirconium oxychloride (ZrOCl)2) Aqueous solution, 4.5mol/L Urea (CON)2H4) 0.8mol/L citric acid (C)6H8O,), 10 wt% Polyethylene (PVA) was mixed in a volume ratio of 2:3:0.8:1.5, followed by addition of 2.66g yttrium nitrate (Y (NO)3)3·6H2O), heating the mixture to 90 ℃, and slowly stirring to 30 mL; then adding 0.10 mu mol/LpH probe-carboxyfluorescein 2',7' -bis (2-carboxylethyl) -5(6) -carboxyfluorescein (BCECF) into the sol to form;
internal phase 60g of molten paraffin (melting point 27 ℃ C.);
(2) gel film preparation
A material is introduced into a channel of a micro-fluidic system by using an injection pump, the micro-fluidic system is shown in figure 1 and comprises a first micro-channel 1, a second micro-channel 2 and a third micro-channel 3 which are positioned on a micro-fluidic main board, the first micro-channel is positioned in the middle of the micro-fluidic main board and extends along the length direction, one end of the first micro-channel is a medium feeding end, and the other end of the first micro-channel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second microchannel and the third microchannel are gathered in the first microchannel and output from the media output end;
in the embodiment of the application, two second microchannels and two third microchannels are respectively arranged, are respectively symmetrically arranged on two sides of the first microchannel and are vertical to the first microchannel;
then inputting the internal phase into a first micro-channel of a micro-fluidic system through a medium feeding end, inputting the intermediate phase into a second micro-channel, and inputting the external phase into a third micro-channel;
external gelation occurs in the microchannel, a gel film is collected in a container containing an external phase solution, and the immersed film is kept stand for 24 hours to fully complete the gelation process; heating the gel membrane to 70 ℃ or soaking the gel membrane in n-octane solution for 24 hours, removing paraffin to form a hollow membrane, and then washing and drying the hollow membrane by using deionized water;
the flow rate control of the medium in each micro-channel is as follows: the first micro channel is 60 mu L/min, the second micro channel is 40 mu L/min, and the third micro channel is 120 mu L/min;
the inner pore size of the first micro-channel is 100 micrometers, the inner pore size of the second micro-channel is 420 micrometers, and the inner pore size of the third micro-channel is 740 micrometers;
(3) sintering of ceramic membranes
Sequentially washing the gel membrane by using trichloroethylene, 1wt% of Triton X-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film for more than 24 hours at room temperature; then gradually heating the gel film to 1500 ℃, and sintering for 47 hours to obtain a ceramic film; the film was then transferred to a crucible and calcined at 200 ℃, 300 ℃ and 600 ℃ for 240 minutes; then gradually raising the temperature to 1100 ℃ and 1500 ℃ and keeping the temperature for 240 minutes respectively to ensure that the zirconia crystal phase is converted from monoclinic tetragonal phase; cooling the ceramic membraneZrO to room temperature to the present application2A ceramic membrane.
Example 2
The method comprises the following steps:
(1) material preparation
The external phase is prepared by adding silicone oil and surfactant span 80(1 wt%), 0.125 vol% tetramethyl diethylamine (TMEDA) into silicone oil;
intermediate phase zirconium sol precursor: the zirconium gel precursor is prepared from 2mol/L zirconium oxychloride (ZrOCl)2) Aqueous solution, 4mol/L Urea (CON)2H4) 0.5mol/L citric acid (C)6H8O),8 wt% Polyethylene (PVA) was mixed at a volume ratio of 2:3:0.8:1.5, followed by addition of 1.33g of yttrium nitrate (Y (NO)3)3·6H2O), heating the mixture to 90 ℃, and slowly stirring to 22 mL; then 0.09. mu. mol/LpH probe-carboxyfluorescein 2',7' -bis (2-carboxylethyl) -5(6) -carboxyfluorescein (BCECF) was added to the sol to form;
internal phase 50g of molten paraffin (melting point 27 ℃ C.);
(2) gel film preparation
A material is introduced into a channel of a micro-fluidic system by using an injection pump, the micro-fluidic system is shown in figure 1 and comprises a first micro-channel 1, a second micro-channel 2 and a third micro-channel 3 which are positioned on a micro-fluidic main board, the first micro-channel is positioned in the middle of the micro-fluidic main board and extends along the length direction, one end of the first micro-channel is a medium feeding end, and the other end of the first micro-channel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second micro-channel and the third micro-channel are gathered in the first micro-channel and output from the media output end;
in the embodiment of the application, two second microchannels and two third microchannels are respectively arranged, are respectively symmetrically arranged on two sides of the first microchannel and are vertical to the first microchannel;
then inputting the internal phase into a first microchannel of a microfluidic system through a medium feeding end, inputting the intermediate phase into a second microchannel, and inputting the external phase into a third microchannel;
external gelation occurs in the microchannel, a gel film is collected in a container containing an external phase solution, and the immersed film is kept stand for 24 hours to fully complete the gelation process; heating the gel membrane to 68 ℃ or soaking the gel membrane in n-octane solution for 24 hours, removing paraffin to form a hollow membrane, and then washing and drying the hollow membrane by using deionized water;
the flow rate control of the medium in each micro-channel is as follows: the first micro-channel is 55 mu L/min, the second micro-channel is 35 mu L/min, and the third micro-channel is 110 mu L/min;
the inner pore diameter of the first micro-channel is 240 micrometers, the inner pore diameter of the second micro-channel is 480 micrometers, and the inner pore diameter of the third micro-channel is 780 micrometers;
(3) sintering of ceramic membranes
Sequentially washing the gel membrane by trichloroethylene, 1wt% TritonX-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film for more than 24 hours at room temperature; gradually heating the gel film to 1500 deg.C, sintering for 47 hr to obtain ceramic film, transferring the film to a crucible, and calcining at 200 deg.C, 300 deg.C and 600 deg.C for 240 min; then gradually raising the temperature to 1100 ℃ and 1500 ℃ and keeping the temperature for 240 minutes respectively so that the zirconia crystal phase is converted from monoclinic to tetragonal; cooling of ceramic membranes to room temperature ZrO of the present application2A ceramic membrane.
Example 3
The method comprises the following steps:
(1) material preparation
2 wt% of surfactant span 80 and 0.25 vol% of Tetramethyldiethylamine (TMEDA) are added into the silicone oil; both span 80 and tetramethyldiethylamine are at final concentrations in silicone oil;
intermediate phase zirconium sol precursor: the zirconium gel precursor is prepared from 2.5mol/L zirconium oxychloride (ZrOCl)2) Aqueous solution, 4.5mol/L Urea (CON)2H4) 0.8mol/L citric acid (C)6H8O,), 10 wt% Polyethylene (PVA) was mixed in a volume ratio of 2:3:0.8:1.5, followed by addition of 2.66g yttrium nitrate (Y (NO)3)3·6H2O), heating the mixture to 90 ℃, and slowly stirring to 30 mL; then 0.10 μmol/LpH Probe-carboxyfluorescein 2',7' -bis (2-carboxyhexyl) -5(6) -carboxyfluorescein (BCECF) added into the sol;
internal phase 58g of molten paraffin (melting point 27 ℃ C.);
(2) gel film preparation
A material is introduced into a channel of the microfluidic system shown in the attached drawing 1-2 by using a syringe pump, the microfluidic system is shown in the attached drawing 1-2 and comprises a first microchannel 1, a second microchannel 2 and a third microchannel 3 which are positioned on a microfluidic mainboard, the first microchannel is positioned in the middle of the microfluidic mainboard and extends along the length direction, one end of the first microchannel is a medium feeding end, and the other end of the first microchannel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second microchannel and the third microchannel are gathered in the first microchannel and output from the media output end;
in the embodiment of the application, two second microchannels and two third microchannels are respectively arranged, are respectively symmetrically arranged on two sides of the first microchannel and are vertical to the first microchannel;
then inputting the internal phase into a first microchannel of a microfluidic system through a medium feeding end, inputting the intermediate phase into a second microchannel, and inputting the external phase into a third microchannel;
external gelation occurs in the microchannel, a gel film is collected in a container containing an external phase solution, and the immersed film is kept stand for 24 hours to fully complete the gelation process; heating the gel membrane to 70 ℃ or soaking the gel membrane in n-octane solution for 24 hours, removing paraffin to form a hollow membrane, and then washing and drying the hollow membrane by using deionized water;
the flow rate control of the medium in each micro-channel is as follows: the first microchannel is 53 muL/min, the second microchannel is 33 muL/min, and the third microchannel is 84 muL/min;
the inner pore diameter of the first micro-channel is 42 micrometers, the inner pore diameter of the second micro-channel is 410 micrometers, and the inner pore diameter of the third micro-channel is 660 micrometers;
(3) sintering of ceramic membranes
Sequentially washing the gel membrane by trichloroethylene, 1wt% TritonX-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film for more than 24 hours at room temperature; then gradually heating the gel film to 1500 ℃, and sintering for 47 hours to obtain a ceramic film; the film was then transferred to a crucible and calcined at 200 ℃, 300 ℃ and 600 ℃ for 240 minutes; then gradually raising the temperature to 1100 ℃ and 1500 ℃ and keeping the temperature for 240 minutes respectively to ensure that the zirconia crystal phase is converted from monoclinic tetragonal phase; ZrO of the present application by cooling the ceramic film to room temperature2A ceramic membrane.
Example 5
The method comprises the following steps:
(1) material preparation
The external phase is that silicone oil and surfactant span 80(1 wt%), 0.125 vol% tetramethyl diethylamine (TMEDA) are added into the silicone oil;
intermediate phase zirconium sol precursor: the zirconium gel precursor is prepared from 2mol/L zirconium oxychloride (ZrOCl)2) Aqueous solution, 4mol/L Urea (CON)2H4) 0.5mol/L citric acid (C)6H8O),8 wt% Polyethylene (PVA) was mixed at a volume ratio of 2:3:0.8:1.5, followed by addition of 1.33g of yttrium nitrate (Y (NO)3)3·6H2O), heating the mixture to 90 ℃, and slowly stirring to 22 mL; then 0.09. mu. mol/LpH probe-carboxyfluorescein 2',7' -bis (2-carboxylethyl) -5(6) -carboxyfluorescein (BCECF) was added to the sol to form;
internal phase 50g of molten paraffin (melting point 27 ℃ C.);
(2) gel film preparation
A material is introduced into a channel of a micro-fluidic system by using an injection pump, the micro-fluidic system is shown in figure 1 and comprises a first micro-channel 1, a second micro-channel 2 and a third micro-channel 3 which are positioned on a micro-fluidic main board, the first micro-channel is positioned in the middle of the micro-fluidic main board and extends along the length direction, one end of the first micro-channel is a medium feeding end, and the other end of the first micro-channel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second micro-channel and the third micro-channel are gathered in the first micro-channel and output from the media output end;
in the embodiment of the application, two second microchannels and two third microchannels are respectively arranged, are respectively symmetrically arranged on two sides of the first microchannel and are vertical to the first microchannel;
then inputting the internal phase into a first microchannel of a microfluidic system through a medium feeding end, inputting the intermediate phase into a second microchannel, and inputting the external phase into a third microchannel;
external gelation occurs in the microchannel, a gel film is collected in a container containing an external phase solution, and the immersed film is kept stand for 24 hours to fully complete the gelation process; heating the gel membrane to 68 ℃ or soaking the gel membrane in n-octane solution for 24 hours, removing paraffin to form a hollow membrane, and then washing and drying the hollow membrane by using deionized water;
the flow rate control of the medium in each micro-channel is as follows: the first micro channel is 77 mu L/min, the second micro channel is 47 mu L/min, and the third micro channel is 135 mu L/min;
the inner pore diameter of the first microchannel is 260 micrometers, the inner pore diameter of the second microchannel is 475 micrometers, and the inner pore diameter of the third microchannel is 785 micrometers;
(3) sintering of ceramic membranes
Sequentially washing the gel film by using trichloroethylene, 1wt% of Triton X-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film for more than 24 hours at room temperature; gradually heating the gel film to 1500 deg.C, sintering for 47 hr to obtain ceramic film, transferring the film to a crucible, and calcining at 200 deg.C, 300 deg.C and 600 deg.C for 240 min; then gradually raising the temperature to 1100 ℃ and 1500 ℃ and keeping the temperature for 240 minutes respectively to ensure that the zirconia crystal phase is converted from monoclinic tetragonal phase; cooling of ceramic membranes to room temperature ZrO of the present application2A ceramic membrane.
Claims (9)
1. A method for preparing a zirconium dioxide hollow film by microfluidics is characterized by comprising the following steps: the method comprises the following steps: firstly, the material preparation is carried out, namely, the material preparation is prepared for preparing ZrO2The raw material of the ceramic film is then passedPreparation of ZrO by microfluidic system2Gel film, ZrO obtained2Sintering the gel film by a ceramic film to obtain a target product;
the material preparation comprises: the external phase is a mixed solution of silicone oil, surfactant span 80 and tetramethyl diethylamine; intermediate phase: adding a pH probe-carboxyl fluorescein into a zirconium gel precursor; wherein, the zirconium gel precursor is formed by firstly mixing zirconium oxychloride aqueous solution, urea, citric acid and polyethylene, then adding yttrium nitrate, heating, stirring and uniformly mixing; internal phase: molten paraffin wax;
the preparation of the gel film specifically comprises the following steps: introducing a material into a channel of a microfluidic system by using an injection pump, wherein the microfluidic system comprises a first microchannel, a second microchannel and a third microchannel which are positioned on a microfluidic mainboard, the first microchannel is positioned in the middle of the microfluidic mainboard and extends along the length direction, one end of the first microchannel is a medium feeding end, and the other end of the first microchannel is a medium output end; the second microchannel and the third microchannel are distributed on the side surface of the first microchannel and are vertically connected with the first microchannel, the second microchannel is positioned at the upstream of the medium circulation, and the third microchannel is positioned at the downstream of the medium circulation; the media in the second microchannel and the third microchannel are gathered in the first microchannel and output from the media output end;
then inputting the internal phase into a first microchannel of a microfluidic system through a medium feeding end, inputting the intermediate phase into a second microchannel, and inputting the external phase into a third microchannel;
then collecting the gel film which passes through the micro-fluidic system and is subjected to gelation in a container containing an external phase solution, and soaking the film to fully complete the gelation process; and then heating or soaking the gel membrane in a normal octane solution to remove paraffin to form a hollow membrane, cleaning and drying the hollow membrane by using deionized water, and sintering the ceramic membrane to obtain a final target product.
2. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 1, wherein: the ceramic membrane sintering specifically comprises the following steps: sequentially washing the gel membrane by using trichloroethylene, 1wt% of Triton X-100 aqueous solution, deionized water and propylene glycol monoethyl ether; then drying the gel film at room temperature; then gradually heating the gel film to 1400-1600 ℃ and 35-55 hours for sintering until a ceramic film is formed, then transferring the film to a crucible, and respectively maintaining the calcination time of 200-260 minutes in the three temperature ranges of 180-220 ℃, 280-320 ℃ and 580-620 ℃; then the temperature is gradually raised to 1000-1200 ℃ and 1450-1550 ℃ and is kept for 260 minutes respectively, so that the zirconia crystal phase is converted from monoclinic to tetragonal, and then the ceramic membrane is cooled to the room temperature.
3. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 2, wherein: the concentration of the surfactant span 80 in the mixed solution is 1wt%, and the concentration of the tetramethyl diethylamine in the mixed solution is 0.125 vol%; the concentration of the zirconium oxychloride aqueous solution is 1.5-3mol/L, the concentration of the urea is 3-5mol/L, the concentration of the citric acid is 0.4-1mol/L, the polyethylene accounts for 6-12 wt%, and the volume ratio of the four components is 2:3:0.8: 1.5.
4. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 3, wherein: the concentration of the zirconium oxychloride aqueous solution is 2mol/L, the concentration of urea is 4mol/L, the concentration of citric acid is 0.5mol/L, and the concentration of polyethylene is 8 wt%.
5. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 2, wherein: the pH probe-carboxyfluorescein adopts 2',7' -bis (2-carboxylethyl) -5(6) -carboxyfluorescein, which corresponds to CAS No. 85138-49-4; the adding amount of the yttrium nitrate is 1-3g, and then the mixture added with the yttrium nitrate is heated to 85-95 ℃ and slowly stirred to 15-30 ml.
6. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 1, wherein: the inner pore diameter of the first micro-channel is 40-300 microns, the inner pore diameter of the second micro-channel is 400-500 microns, and the inner pore diameter of the third micro-channel is 600-800 microns; the medium flow of the first micro channel is 50-80 muL/min, the medium flow of the second micro channel is 30-50 muL/min, and the medium flow of the third micro channel is 80-150 muL/min.
7. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 3, wherein: at least one second microchannel is arranged; the number of the third micro-channels is at least one.
8. The method for microfluidically preparing a zirconium dioxide hollow thin film according to claim 7, wherein: the number of the second micro-channels is two, and the two second micro-channels are vertically connected with the first micro-channel and symmetrically distributed on two sides of the first micro-channel; the number of the third micro-channels is two, and the two third micro-channels are vertically connected with the first micro-channel and symmetrically distributed on two sides of the first micro-channel.
9. The method for the microfluidic preparation of a zirconium dioxide hollow membrane according to claim 1, wherein: immersing the gelated gel film in a container containing an external phase solution, and standing for 20-30 hours to fully complete the gelated process; then heating the gel film to 60-80 ℃ or soaking the gel film in n-octane solution for 20-30 hours to remove paraffin to form a hollow film.
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