LU601110B1

LU601110B1 - Preparation method of high flux ceramic microfiltration membrane

Info

Publication number: LU601110B1
Application number: LU601110A
Authority: LU
Inventors: Gangling Chen
Original assignee: Univ Chuzhou
Priority date: 2025-04-15
Filing date: 2025-04-15
Publication date: 2025-10-15

Abstract

The present invention pertains to the technical field of inorganic ceramic membranes, and specifically relates to a preparation method of high-flux ceramic microfiltration membrane, including a microfiltration ceramic coating solution and the preparation of an intermediate-layer-free alumina ceramic microfiltration membrane. The specific technical solution is as follows: A microfiltration ceramic coating solution includes alumina powder, a binder, a binding auxiliary agent, and a dispersant. The binder is methyl cellulose, the binding auxiliary agent is a silane coupling agent (KH-550), and the dispersant is polyacrylic acid. By applying the microfiltration ceramic coating solution provided in this invention to the preparation of ceramic membranes, intermediate transition layers can be eliminated, thereby reducing the production time and cost of ceramic microfiltration membranes. Moreover, the prepared alumina ceramic membrane exhibits an exceptionally high pure water permeation flux of 1971 L·m-2·h-1·bar-1, significantly surpassing that of ceramic membranes prepared using conventional methods.

Description

DESCRIPTION LU601110

PREPARATION METHOD OF HIGH FLUX CERAMIC MICROFILTRATION

MEMBRANE

TECHNICAL FIELD

The invention relates to the technical field of inorganic ceramic membranes, in particular to a preparation method of a ceramic microfiltration membrane with high permeation flux, which includes the preparation of a microfiltration ceramic coating solution and an alumina ceramic microfiltration membrane without an intermediate layer.

BACKGROUND

Ceramic microfiltration membrane is a porous membrane mainly prepared from inorganic materials such as AlO3, ZrO2, TiO2, SiO2, etc, and is widely used in water treatment, food and beverage processing, biomedicine, and other fields. In recent years,

SiC material has also been used to produce ceramic membranes for gas separation, and silicon carbide ceramic membranes have shown good performance in antibacterial applications. Compared with similar organic membranes, ceramic membranes have advantages such as high-temperature resistance, bacterial resistance, good chemical stability, and high mechanical strength, but their high cost hinders their industrial development.

Traditional ceramic microfiltration membranes can only be produced through multiple steps: first, preparing a support body to provide mechanical strength for the membrane layer; then coating one or more intermediate transition layers on the support body; and finally forming a microporous separation layer. Each step involves a high-temperature sintering process, making the preparation cost of ceramic microfiltration membranes relatively high. If ceramic microfiltration membranes can be prepared without intermediate layers, it would significantly reduce their production time and cost.

SUMMARY LU601110

To address the shortcomings of existing technologies, the present invention provides a microfiltration ceramic coating solution and a preparation method for an alumina ceramic microfiltration membrane without intermediate layers. By applying the microfiltration ceramic coating solution provided by this invention to the preparation of ceramic membranes, the intermediate transition layers can be eliminated, thereby reducing the production time and cost of ceramic microfiltration membranes.

To achieve the above objectives, the invention is realized through the following technical schemes:

The invention discloses a microfiltration ceramic coating solution, including alumina powder, a binder, a binding auxiliary agent, and a dispersant. The binder is methyl cellulose, the binding auxiliary agent is a silane coupling agent (KH-550), and the dispersant is polyacrylic acid.

Preferably, the mass ratio of the alumina powder, binder, and dispersant is 10-15:0.2- 0.5:0.2-1, and the volume ratio of the binding auxiliary agent to deionized water is 0.5- 1:82.5-89.1.

Correspondingly, a preparation method for the microfiltration ceramic coating solution involves adding deionized water to a beaker and heating it, then adding the binder and dispersant. After dissolution, the binding auxiliary agent is added to obtain a suspension. The alumina powder is then added to the suspension, and after stirring for a period of time, the coating solution is obtained.

Preferably, the particle size of the alumina powder is 0.8-2.6 um, and the purity of

KH-550 is 99.8%.

Correspondingly, a preparation method for an alumina ceramic microfiltration membrane without intermediate layers involves coating the coating solution onto a support body. After drying, an alumina microfiltration ceramic green body is obtained, which is then sintered to yield the alumina ceramic microfiltration membrane without intermediate layers.

Preferably, the coating solution is applied using a dip-coating method, with a dipping speed of 1-2 cm/s, a withdrawal speed of 2-3 cm/s, and an immersion time of 30-60 s.

Preferably, the support body is a tubular alumina ceramic support.

Preferably, the sintering temperature is 1100-1300°C, with a holding time of 2 h.

Preferably, the heating rate during sintering is 2-5 °C/min.

The invention offers the following beneficial effects:

1. the invention uses KH-550 to couple methyl cellulose and alumina, enhancing tne 601110 adhesion of methyl cellulose while improving the dispersibility and film-forming properties of the coating solution. This enables the one-step preparation of a ceramic membrane without intermediate layers, eliminating the need for intermediate layer preparation, shortening production time, and reducing costs. 2. The coating solution prepared in this invention is uniform and stable, with almost no sedimentation within 48 h. Moreover, traditional coating typically requires multiple applications, whereas this invention requires only a single coating, significantly reducing the number of coating steps. 3. The alumina ceramic membrane prepared by this invention exhibits a pure water permeation flux as high as 1971 L-m?-h"-bar*, far exceeding that of ceramic membranes prepared by traditional methods.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is the SEM morphology diagram of the surface and section of Embodiment 1;

Fig. 2 is the contrast diagram of pure water flux between the support and

Embodiment 1.

DESCRIPTION OF THE INVENTION

In the following, the technical scheme in the embodiment of the invention will be clearly and completely described with reference to the attached drawings. Obviously, the described embodiment is only a part of the embodiment of the invention, but not the whole embodiment. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative labor belong to the scope of protection of the present invention.

Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art. 1. The present invention discloses a microfiltration ceramic coating solution including alumina powder, a binder, a binding auxiliary agent, and a dispersant.

The binder is methyl cellulose, the binding auxiliary agent is a silane coupling agent (KH-550), and the dispersant is polyacrylic acid.

2. The mass ratio of the alumina powder, binder, and dispersant is 10-15:0.20 601110 0.5:0.2-1, and the volume ratio of the binding auxiliary agent to deionized water is 0.5-1:82.5-89.1. 2. The invention further discloses a preparation method for the microfiltration ceramic coating solution. Deionized water is added to a beaker and heated, followed by the addition of the binder and dispersant. After dissolution, the binding auxiliary agent is added to obtain a suspension. The alumina powder is then introduced into the suspension, and after stirring for a period, the coating solution is obtained.

Further, the alumina powder has a particle size of 0.8-2.6 um, and the purity of KH- 550 is 99.8%. 3. The invention also discloses a preparation method for an intermediate-layer-free alumina ceramic microfiltration membrane. The coating solution is applied onto a support body, dried to form an alumina microfiltration ceramic green body, and then sintered to obtain the final membrane.

Specifically: the coating solution is applied via dip-coating, with an immersion speed of 1-2 cm/s, a withdrawal speed of 2-3 cm/s, and an immersion time of 30-60 s. The support body is a tubular alumina ceramic support. The sintering temperature is 1100- 1300 °C, with a holding time of 2 h. The heating rate during sintering is 2-5 °C/min.

The invention is further elaborated below with specific embodiments.

Embodiment 1

Preparation of a high-flux, intermediate-layer-free alumina ceramic microfiltration membrane: (1) under constant temperature at 70°C, dissolve 0.2 g of methyl cellulose and 0.5 g of polyacrylic acid in 88.8 mL of deionized water with stirring to form a uniform suspension; (2) stop heating, add pre-weighed alumina powder (0.8 um) into the suspension, disperse evenly, then introduce 0.5 mL of silane coupling agent (KH-550). Stir for about 4 h to obtain a homogeneous coating solution, followed by standing for bubble removal. (3) Clean a tubular porous alumina support with deionized water and dry at 100°C for 2 h. Apply the coating solution via dip-coating for 60 s. After air-drying at room temperature for 1 h, dry in an oven at 80°C for 2 h.

Finally, sinter in a muffle furnace at 1200°C for 2 h, then cool naturally to room temperature to obtain the alumina ceramic membrane.

The surface and cross-section of the sample from Embodiment 1 are examined by

SEM, and the results are shown in Fig. 1. Where, images a, b, and c show the surface morphology at 5000x, 2000x, and 1000x magnification, respectively. Images a and Ris01110 clearly reveal abundant micropores on the membrane surface, with alumina particles tightly bonded. Image c demonstrates a smooth, defect-free surface, indicating excellent film-forming properties and successful dip-coating, resulting in a well-integrated alumina layer. Image d (500x cross-sectional view) shows a membrane thickness of ~25 um, with strong adhesion between the membrane and support. The support layer exhibits much larger pores than the alumina particles in the membrane layer, yet minimal particle infiltration into the support, avoiding clogging. These results confirm the feasibility of this one-step method for preparing intermediate-layer-free ceramic microfiltration membranes.

Embodiment 2

Preparation of a high-flux, intermediate-layer-free alumina ceramic microfiltration membrane: (1) at the constant temperature of 70°C, 0.3 g of methyl cellulose and 0.2 g of polyacrylic acid are dissolved in 89.5 mL of deionized water, and they are fully dissolved by stirring to make a suspension; (2) stop heating, add the weighed alumina (0.94 um) into the suspension, add 0.5 mL silane coupling agent (KH-550) after uniform dispersion, stir for about four hours to obtain a uniform coating solution, and stand for defoaming. (3) Clean the tubular porous alumina support with deionized water and dry it in an oven at 100°C for two hours. Dip coating method is used to coat the film. After coating for s, the film tube is dried at room temperature for 1 h and then put into an oven at 80°C for 2 h. Then it is heated to 1100°C in a muffle furnace, sintered for 2 h, and then naturally cooled to room temperature to obtain the alumina ceramic membrane.

Embodiment 3

Preparation of a high-flux, intermediate-layer-free alumina ceramic microfiltration membrane: (1) under constant temperature at 70°C, dissolve 0.4 g of methyl cellulose and 0.8 g of polyacrylic acid in 87.8 mL of deionized water with stirring to form a uniform suspension; (2) stop heating, add the weighed alumina (2.6 um) into the suspension, add 1 mL silane coupling agent (KH-550) after uniform dispersion, stir for about four hours to obtain a uniform coating solution, and stand for defoaming. (3) Clean a tubular porous alumina support with deionized water and dry at 100°C for 2 h. Apply the coating solution via dip-coating for 30 s. After air-drying at room temperature for 1 h, dry in an oven at 80°C for 2 h. Finally, sinter in a muffle furnace at

1300°C for 2 h, then cool naturally to room temperature to obtain the alumina ceramic 601110 membrane.

The stability and film-forming performance of the alumina microfiltration membrane coating solution prepared in Embodiments 1-3 are tested. The stability of the coating solution is measured by sedimentation method, and the lower the sedimentation volume percentage of the coating solution, the higher the stability; the film-forming performance is evaluated by apparent grade, and three evaluation grades are set: (1) there are more pinholes and wrinkles, (2) there are a few pinholes and wrinkles, and (3) there are no pinholes and wrinkles. The higher the grade, the better the film-forming performance of the coating solution. The results are shown in Table 1.

Table 1 Test results of stability and film-forming performance of microfiltration membrane coating solution in Embodiments 1-3

Settlement Leveling

Sample volume (%) grade

Embodiment 3.2 3 1

Embodiment 4.6 3 2

Embodiment 2.8 3 3

As can be seen from the results in Table 1, the microfiltration membrane coating solution provided by the invention has good stability, is not easy to settle, has good membrane forming performance, and has a flat surface without pinholes and wrinkles.

The above-mentioned embodiments only describe the preferred mode of the invention, and do not limit the scope of the invention.

Under the premise of not departing from the design spirit of the invention, various «1g modifications and improvements made by ordinary technicians in the field to the technical scheme of the invention shall fall within the protection scope determined by the claims of the invention.

Claims

CLAIMS LU601110

1. A microfiltration ceramic coating solution, comprising alumina powder, a binder, a binding auxiliary agent, and a dispersant; wherein the binder is methyl cellulose, the binding auxiliary agent is a silane coupling agent (KH-550), and the dispersant is polyacrylic acid.

2. The microfiltration ceramic coating solution according to claim 1, characterized in that the mass ratio of the alumina powder, binder, and dispersant is 10-15:0.2-0.5:0.2-1, and the volume ratio of the binding auxiliary agent to deionized water is 0.5-1:82.5-89.1.

3. A preparation method for the microfiltration ceramic coating solution according to claim 1 or 2, characterized in that adding deionized water to a beaker and heating, then adding the binder and dispersant; after dissolution, adding the binding auxiliary agent to obtain a suspension; then adding alumina powder to the suspension, and stirring for a period of time to obtain the coating solution.

4. The preparation method according to claim 3, characterized in that the alumina powder has a particle size of 0.8-2.6 um, and the KH-550 has a purity of 99.8%.

5. A preparation method for intermediate-layer-free alumina ceramic microfiltration membrane, characterized in that coating the coating solution according to claim 1 or 2 onto a support body, drying to obtain an alumina microfiltration ceramic green body, and then sintering the green body to obtain the intermediate-layer-free alumina ceramic microfiltration membrane.

6. The preparation method according to claim 5, characterized in that the coating solution is applied by dip-coating, with an immersion speed of 1-2 cm/s, a withdrawal speed of 2-3 cm/s, and an immersion time of 30-60 Ss.

7. The preparation method according to claim 5, characterized in that the support body is a tubular alumina ceramic support.

8. The preparation method according to claim 5, characterized in that the sintering temperature is 1100-1300°C, with a holding time of 2 h.

9. The preparation method according to claim 5 or 8, characterized in that the heating, 110 rate during sintering is 2-5°C/min.