Differences between inorganic and organic ceramic membranes

Research on inorganic ceramic membranes began in the 1940s, and breakthroughs were made in the late 1980s. Research on inorganic ceramic membranes and separation technology in China started late, but is developing at a faster pace. Due to the advantages of high efficiency, high temperature resistance, reliable operation and good chemical stability, inorganic ceramic membrane technology has a very promising future. Inorganic ceramic membranes have the following characteristics compared to polymeric organic membranes.

1. Inorganic ceramic membrane pore size distribution is narrow, its distribution is normal, error ± 10% within the pore size accounted for more than 80%, such as 0.05μm membrane, 0.049μm-0.051μm between the membrane pore size accounted for 80% of the total membrane pore size, to ensure the stability of the membrane treatment effect used; this is a major difference with organic membranes, organic membranes are generally retained molecular weight to characterize the membrane pore size, its pore size distribution is also generally based on the average distribution. This differs from organic membranes, where the pore size is generally characterised by the amount of molecules retained and the pore size distribution is generally average.

2. Inorganic ceramic membranes have a high porosity of 35-40%, ensuring high membrane fluxes.

3. Inorganic ceramic membrane separation layer structure is more reasonable, the separation layer and support layer a total of 4 layers, pore size of 5-10, 1.0, 0.6, 0.2μm, forming a real sense of the gradient membrane or asymmetric membrane, improve the membrane's anti-pollution ability, the role of the separation layer is thinner, 20μm thick, membrane cleaning is also more simple and convenient; while organic membranes are generally symmetric membrane, anti-pollution ability is poor, into the membrane need After strict pretreatment.

4. Inorganic ceramic membranes are strong, the membrane layer can withstand up to 16 bar and the support body can withstand up to 30 bar, which is not easy to damage, ensuring the effect and stability of the treatment quality when using the membrane treatment.

5. High insulating properties of inorganic ceramic membranes.

6. Long service life of inorganic ceramic membranes, typically over 5 years, compared to 3 to 6 months for organic membranes.

7. Inorganic ceramic membranes have better chemical stability (pH range 0-14) and thermal stability (up to 400°C) than organic membranes, and can use strong acids, bases and oxidants as cleaning agents, making cleaning and regeneration more convenient and easy; and can be directly steam sterilised. Organic membranes generally cannot be operated at high temperatures, strong alkalis or strong acids and oxidisers.

From the literature, the use of membranes in the paper waste treatment process are to use strong oxidant hydrogen peroxide or sodium hypochlorite for cleaning, and organic membranes are most afraid of contact with strong oxidants, and generally require that organic membranes be immersed in 1% sodium bisulfite solution (reducing agent) when stopped for more than 24 hours to prevent air oxidation; at the same time, the hydrophilicity of ceramic membranes is also stronger than most organic membranes, which ensures that ceramic membranes in the treatment of water than organic membranes higher permeability and permeate flux per unit area.