Heterojunction ceramic composite nanofiltration membrane and preparation method thereof

Abstract

The application discloses a kind of heterojunction ceramic composite nanofiltration membranes and preparation method, comprising: using in-situ hydrothermal method MoS2 Ceramic composite membrane is prepared;MoS2 Ceramic composite membrane is placed in the tubular muffle furnace with temperature of 100~500 ℃, and heat annealing is carried out in air atmosphere;After 10~120 min, it is taken out and cooled to room temperature, and MoS2 / MoO3 Heterojunction ceramic composite nanofiltration membrane is prepared.The preparation method of the application is simple, and the MoS2 / MoO3 Heterojunction ceramic composite nanofiltration membrane prepared has good structural stability, and nanofiltration separation performance is excellent, and shows better application potential in dye wastewater treatment and other fields.

Description

Technical Field

[0001] This invention relates to the field of membrane separation technology, specifically to a heterojunction ceramic composite nanofiltration membrane and its preparation method. Background Technology

[0002] Molybdenum disulfide (MoS2) is a typical two-dimensional layered material. A single layer of MoS2 consists of three atomic layers, with a layer of Mo atoms sandwiched between two S atomic layers. Adjacent MoS2 layers are held together by van der Waals forces, with an interlayer spacing of 0.62 nm. MoS2 nanosheets possess high mechanical strength, excellent swelling resistance and chemical stability, and have clean 2D channels, making them considered an ideal membrane material. Studies have shown that the water flux of MoS2 laminated membranes prepared by vacuum filtration is 3-5 times that of graphene oxide laminated membranes of the same thickness (Chem. Commun. 2013, 49, 10718-10720). Patent CN107486045A adds MoS2 particles as an additive to a cationic polyelectrolyte solution, and further obtains a MoS2 / polyelectrolyte hybrid nanofiltration membrane through a layer-by-layer self-assembly method. The water flux of the composite membrane prepared under optimal conditions is 8.37 L·m. -2 ·h -1 ·bar -1 The rejection rate for methylene blue was 96.6%. Patent CN108339412A prepared a MoS2 ceramic composite nanofiltration membrane on a ceramic substrate using an in-situ hydrothermal method. The prepared ceramic composite membrane exhibited good nanofiltration performance not only in dye / water systems but also in dye / organic solvent systems. Patent CN113663530A used a tubular ceramic membrane as a substrate, first preparing a MoS2 intermediate layer on its surface using an in-situ hydrothermal method, and then preparing a polyamide (PA) dense layer using an interfacial polymerization method to prepare a PA / MoS2 ceramic composite nanofiltration membrane. The resulting composite membrane had a Na2SO4 rejection rate of 94.8% and a water flux of 17.7 L·m³. -2 ·h -1 ·bar -1 However, the strong hydrophobicity of the MoS2 ceramic membrane surface is the main factor limiting the permeation performance of MoS2-based nanofiltration membranes.

[0003] To improve the hydrophilicity of MoS2 ceramic membranes, the common approach is to composite or graft hydrophilic groups onto the MoS2 surface. Guo et al. prepared a hydroxyl-modified hydrophilic MoS2 ceramic composite nanofiltration membrane using an in-situ hydrothermal method, and the permeability of the prepared composite membrane was twice that of the original MoS2 membrane (J.Membr.Sci.2020,659,120777). However, while hydrophilic functional groups improve the hydrophilicity of MoS2 ceramic membranes, the hydrogen bonding interactions with water molecules can lead to high mass transfer resistance, limiting the transport of water molecules within the membrane pores. Due to the good hydrophilicity of MoO3, Zhang et al. designed and synthesized MoS2 / MoO3 heterojunction nanosheets through an H2O2 oxidation process, which improved the surface affinity and electrocatalytic activity of MoS2 nanosheets. The lithium-sulfur batteries prepared using these nanosheets as modified materials for battery separators exhibited excellent electrochemical performance (ACS Nano 2021,15,20478-20488). However, modifying MoS2-based ceramic nanofiltration membranes with hydrophilic MoO3 remains a technical challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a heterojunction ceramic composite nanofiltration membrane and its preparation method. The preparation method is simple, and the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane exhibits good structural stability and excellent nanofiltration separation performance, showing good application potential in fields such as dye wastewater treatment.

[0005] This invention discloses a method for preparing a heterojunction ceramic composite nanofiltration membrane, comprising:

[0006] MoS2 ceramic composite membranes were prepared using an in-situ hydrothermal method.

[0007] The MoS2 ceramic composite membrane was placed in a tube muffle furnace at a temperature of 100–500 °C and annealed in air atmosphere. After 10–120 min, it was removed and cooled to room temperature to prepare the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0008] As a further improvement of the present invention, the preparation of the MoS2 ceramic composite membrane by in-situ hydrothermal method includes:

[0009] Ammonium molybdate and thiourea were mixed and dissolved in deionized water to obtain a precursor solution;

[0010] The precursor solution and the ceramic substrate were transferred together to a stainless steel reactor for hydrothermal reaction to prepare a MoS2 ceramic composite film on the surface of the ceramic substrate.

[0011] As a further improvement of the present invention, the temperature of the heat annealing is 200-350°C and the time is 60-100 min.

[0012] As a further improvement of the present invention, the temperature of the heat annealing is 300°C and the time is 80 minutes.

[0013] The present invention also discloses a heterojunction ceramic composite nanofiltration membrane, which is prepared by the above-described method for preparing heterojunction ceramic composite nanofiltration membrane.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] This invention is the first to employ a strategy combining in-situ hydrothermal method and thermal annealing to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane for nanofiltration separation. Its surface morphology is shown in the attached figure. Figure 1 Scanning electron microscope images and appendices Figure 2 As shown in the electron microscope image, MoO3's excellent hydrophilicity effectively improves the surface hydrophilicity of the MoS2 ceramic composite membrane, promotes water molecule transport, and enhances the membrane's permeability. Furthermore, MoO3's high surface charge density enhances the membrane's surface negative charge. Based on these factors, the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane exhibits both high permeability and excellent selective separation performance, while also demonstrating excellent pressure resistance and long-term operational stability. Attached Figure Description

[0016] Figure 1 The images show the surface and cross-sectional scanning electron microscope morphology of the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane prepared in Example 3 of this invention, as well as its elemental analysis diagram.

[0017] Figure 2 Transmission electron microscopy (TEM) images of MoS2 powder prepared in the comparative examples of the present invention and MoS2 / MoO3 heterojunction ceramic film prepared in Example 3, showing MoS2 and MoO3 nanosheets on their surfaces; wherein, a and b are comparative examples, and d and e are examples 3.

[0018] Figure 3 The surface water contact angles of the MoS2 ceramic composite membrane prepared in the comparative examples of the present invention and the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membranes prepared in Examples 1-7 are shown.

[0019] Figure 4 The surface Zeta potential of the MoS2 ceramic composite membrane prepared in the comparative examples of the present invention and the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane prepared in Examples 1-7 are shown.

[0020] Figure 5 The nanofiltration performance of the MoS2 ceramic composite membrane prepared in the comparative examples of the present invention and the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane prepared in Examples 1 to 7 is compared.

[0021] Figure 6 The pressure resistance and long-term operational stability of the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane prepared in Example 3 of this invention are tested; wherein, (a) is the pressure resistance test and (b) is the long-term operational stability test. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings:

[0024] This invention provides a method for preparing a heterojunction ceramic composite nanofiltration membrane formed from molybdenum disulfide (MoS2) and molybdenum oxide (MoO3), comprising:

[0025] Step 1: Referring to the technology disclosed in patent CN108339412A, an in-situ hydrothermal method is used to prepare a MoS2 ceramic composite membrane; specifically:

[0026] Ammonium molybdate and thiourea in a mass ratio of 1:2 were mixed and dissolved in deionized water to obtain a precursor solution. The precursor solution and the ceramic substrate were transferred together to a stainless steel reactor for hydrothermal reaction to prepare a MoS2 ceramic composite membrane on the surface of the ceramic substrate.

[0027] Step 2: Place the MoS2 ceramic composite membrane in a tube muffle furnace at a temperature of 100–500℃ and perform hot annealing in an air atmosphere; after 10–120 min, remove it and cool it to room temperature to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane; wherein,

[0028] The preferred temperature for hot annealing is 200–350°C, more preferably 250–350°C, and most preferably 300°C; the preferred time for hot annealing is 60–100 min, more preferably 70–80 min, and most preferably 80 min.

[0029] This invention provides a heterojunction ceramic composite nanofiltration membrane, which is prepared by the above-described method for preparing heterojunction ceramic composite nanofiltration membrane.

[0030] Comparative Examples

[0031] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 hours to obtain a MoS2 ceramic composite membrane.

[0032] The nanofiltration performance of the prepared MoS2 ceramic composite membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane had a xylenol orange rejection rate of 98.9% and a water flux of 11.7 L·m³. -2 ·h -1 ·bar -1 .

[0033] Example 1

[0034] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 100°C and thermally annealed in air for 120 min. Afterward, it was removed and cooled to room temperature to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0035] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane had a xylenol orange rejection rate of 98.5% and a water flux of 15.1 L·m³. -2 ·h -1 ·bar -1 .

[0036] Example 2

[0037] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 200°C and annealed in air for 100 min. Afterward, it was removed and cooled to room temperature to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0038] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane had a xylenol orange rejection rate of 98.1% and a water flux of 24.3 L·m³. -2 ·h -1 ·bar -1 .

[0039] Example 3

[0040] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 300°C and thermally annealed in air for 80 min. Afterward, it was removed and cooled to room temperature to obtain a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0041] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane had a xylenol orange rejection rate of 97.4% and a water flux of 32.8 L·m³. -2 ·h -1 ·bar -1 .

[0042] This invention is the first to employ a strategy combining in-situ hydrothermal method and thermal annealing to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane for nanofiltration separation. Its surface morphology is shown in the attached figure. Figure 1 Scanning electron microscope images and appendices Figure 2 As shown in the electron microscope image; due to the good hydrophilicity of MoO3, the surface hydrophilicity of the MoS2 ceramic composite film is effectively improved (e.g., Figure 3 As shown in the figure, it promotes water molecule transport and improves the membrane's permeability; in addition, MoO3 has a high surface charge density, which enhances the membrane's surface charge negativeness (e.g., Figure 4 (As shown). Based on this, the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane possesses both high permeability and excellent selective separation performance. For example, the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane prepared in Example 3 has a rejection rate of 97.4% for xylenol orange and a water flux of 32.8 L·m. -2 ·h -1 ·bar -1Compared to the comparative examples, this MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane exhibits approximately three times improved permeability while maintaining a similar rejection rate (e.g., Figure 5 (As shown). Furthermore, the MoS2 / MoO3 heterostructure composite nanofiltration membrane also exhibits excellent pressure resistance and long-term operational stability (e.g., Figure 6 (As shown).

[0043] Example 4

[0044] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 350°C and thermally annealed in air for 60 min. Afterward, it was removed and cooled to room temperature to obtain a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0045] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane exhibited a xylenol orange rejection rate of 92.4% and a water flux of 36.4 L·m³. -2 ·h -1 ·bar -1 .

[0046] Example 5

[0047] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 400°C and thermally annealed in air for 40 min. Afterward, it was removed and cooled to room temperature to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0048] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane exhibited a xylenol orange rejection rate of 90.2% and a water flux of 41.5 L·m³. -2 ·h -1 ·bar -1 .

[0049] Example 6

[0050] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 450°C and annealed in air for 20 min. Afterward, it was removed and cooled to room temperature to obtain a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0051] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane exhibited a xylenol orange rejection rate of 88.2% and a water flux of 46.5 L·m³. -2 ·h -1 ·bar -1 .

[0052] Example 7

[0053] Ammonium molybdate and thiourea in a mass ratio of 1:2 were dissolved in deionized water to obtain a precursor solution. This precursor solution was then transferred together with a ceramic substrate to a stainless steel reactor and heated at 220°C for 30 h to obtain a MoS2 ceramic composite membrane. The prepared MoS2 ceramic composite membrane was then placed in a tubular muffle furnace at 500°C and annealed in air for 10 min. Afterward, it was removed and cooled to room temperature to prepare a MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

[0054] The nanofiltration performance of the prepared MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane was tested under the following conditions: room temperature, feed solution of 0.1 g / L xylenol orange aqueous solution, and test pressure of 0.2 MPa. The results showed that the prepared MoS2 ceramic composite membrane exhibited a xylenol orange rejection rate of 76.2% and a water flux of 52.3 L·m³. -2 ·h -1 ·bar -1 .

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a heterojunction ceramic composite nanofiltration membrane, characterized in that, include: MoS2 ceramic composite membranes were prepared using an in-situ hydrothermal method. The MoS2 ceramic composite membrane was placed in a tube muffle furnace at a temperature of 100–500 °C and annealed in air atmosphere. After 10–120 min, it was removed and cooled to room temperature to prepare the MoS2 / MoO3 heterojunction ceramic composite nanofiltration membrane.

2. The method for preparing the heterojunction ceramic composite nanofiltration membrane as described in claim 1, characterized in that, The preparation of MoS2 ceramic composite membranes using the in-situ hydrothermal method includes: Ammonium molybdate and thiourea were mixed and dissolved in deionized water to obtain a precursor solution; The precursor solution and the ceramic substrate were transferred together to a stainless steel reactor for hydrothermal reaction to prepare a MoS2 ceramic composite film on the surface of the ceramic substrate.

3. The method for preparing the heterojunction ceramic composite nanofiltration membrane as described in claim 1, characterized in that, The heat annealing temperature is 200–350°C, and the time is 60–100 min.

4. The method for preparing the heterojunction ceramic composite nanofiltration membrane as described in claim 3, characterized in that, The heat annealing temperature is 300℃ and the time is 80 minutes.

5. A heterojunction ceramic composite nanofiltration membrane, characterized in that, The heterojunction ceramic composite nanofiltration membrane is prepared by the method described in any one of claims 1 to 4.

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