Using HPMC additives to improve the permeability of ceramic membranes

1. Introduction

Ceramic membranes are widely used in water treatment, chemical and food industries due to their excellent chemical stability, mechanical strength and high temperature resistance. However, the permeability of ceramic membranes is low, which limits their application scope and efficiency. Improving the permeability of ceramic membranes can significantly improve their performance and expand their application prospects.

2. Overview of HPMC

Hydroxypropyl Methylcellulose (HPMC) is an important cellulose derivative, which is prepared by methylation and hydroxypropylation of cellulose. It has excellent film-forming, thickening and surface activity, and is widely used in food, medicine, construction and other fields. In the preparation of ceramic membranes, HPMC acts as a pore-forming agent and dispersant to adjust the pore structure and permeability of the membrane.

3. Mechanism of improving the permeability of ceramic membranes

(3.1) HPMC as a pore-forming agent

HPMC plays an important pore-forming role in the preparation of ceramic membranes. The pore structure and pore size distribution of ceramic membranes directly affect their permeability. HPMC can form a uniform dispersion system in the solvent. As the solvent evaporates, HPMC forms microscopic channels in the membrane. These channels form a stable ceramic membrane pore structure through subsequent sintering treatment, which improves the permeability of the membrane.

(3.2) Effect of HPMC on slurry rheological properties

In the preparation of ceramic membranes, the rheological properties of the slurry have a key influence on the formation and final structure of the membrane. HPMC, as a thickener, can improve the rheological properties of the slurry, making it more uniform and flat during the film forming process. Appropriate rheological properties help to uniformly distribute and control the pores of the membrane, thereby improving the permeability of the membrane.

4. Preparation method of HPMC modified ceramic membrane

(4.1) Method of adding HPMC

HPMC, like HPMC E50, can be directly added to the ceramic slurry to modify the ceramic membrane. Common methods include:

Direct mixing method: Dissolve HPMC in water or other solvents, and then mix it with ceramic powder to make a uniform slurry. This method is easy to operate, but the amount of HPMC added needs to be controlled to avoid excessive slurry viscosity.

Pretreatment method: Made by the HPMC manufacturer, this product is mixed with ceramic powder and then pretreated, such as ball milling or ultrasonic dispersion. This method can enhance the bonding force between HPMC and ceramic powder and improve the modification effect.

(4.2) Optimization of sintering process

During the sintering process, HPMC decomposes and volatilizes to form stable ceramic membrane pores. Optimizing the sintering temperature and time can control the pore structure and improve the permeability of the membrane. Generally, the sintering temperature is more suitable between 1000-1500°C, which can effectively remove HPMC and form a uniform ceramic membrane structure.

5. Effect of HPMC on the performance of ceramic membranes

(5.1) Improvement of permeability and selectivity

Adding HPMC can significantly improve the permeability of ceramic membranes and increase water flux or gas flux. For example, studies have shown that when the HPMC addition amount is 0.5-2 wt%, the permeability of ceramic membranes can be increased by 20-50%. At the same time, the selectivity of HPMC-modified membranes is also improved, which is of great significance for the separation of different particles or molecules.

(5.2) Mechanical properties and stability

The mechanical properties and chemical stability of HPMC-modified ceramic membranes are improved compared to unmodified membranes. The pore structure formed by HPMC in the membrane can disperse stress to a certain extent, increasing the toughness and impact resistance of the membrane. In addition, HPMC, as an organic matter, completely decomposes at high temperatures and does not affect the chemical stability of the ceramic membrane.

6. Typical applications and research cases

(6.1) Water treatment

HPMC-modified ceramic membranes show excellent performance in the field of water treatment. The modified membranes can be used in processes such as microfiltration and ultrafiltration to improve the efficiency of water purification. For example, a study showed that HPMC-modified ceramic membranes showed higher flux and anti-fouling performance in sewage treatment.

(6.2) Gas separation

In the field of gas separation, HPMC-modified ceramic membranes also show higher permeability and selectivity. For the separation of gases such as CO₂ and O₂, the modified membranes can provide higher separation efficiency and are suitable for industrial gas purification and recovery.

By adding HPMC to the ceramic membrane, the permeability and selectivity of the membrane can be significantly improved. This modification method is simple and efficient, which not only improves the performance of ceramic membranes, but also expands their application range. In future research, further optimizing the HPMC addition method and sintering process and developing ceramic membranes with higher performance will help promote the application of ceramic membranes in more fields.