Introduction of ceramic membranes

Ceramic membrane, also known as inorganic ceramic membrane is an asymmetric membrane inorganic ceramic material specially prepared by the process of the formation. Please note, "CT film" is not an alias ceramic membrane, which is a non-title real professionals a wrong representation of the English abbreviation of the ceramic membrane. Clouds microporous ceramic membrane wall, under pressure, in the raw material liquid film flow on the outside tube or a membrane, small molecules (or liquid) permeable membrane, macromolecules (or solid) retained by the membrane, to achieve separation, concentration, purification and environmental protection purposes. Ceramic membrane having a high separation efficiency, stable, good chemical stability, high acid and alkali resistance, organic solvent resistance, bacteria, temperature, contamination, mechanical strength, good regeneration properties, the separation process is simple, low energy consumption, operation and maintenance simple, long life and many other advantages, has been successfully used in many fields such as food, beverages, plant (drug) material processing, bio-pharmaceutical, fermentation, fine chemicals, etc., it can be used in the process of separation, clarification, purification and concentration, in addition to bacteria, desalination and so on.

Inorganic ceramic membrane is a membrane, the membrane separation technique belonging solid film materials, mainly inorganic ceramic material of different specifications, alumina, zirconia, titanium oxide and silicon oxide as a support, by coating the surface of high temperature fired from. Commercialization of ceramic membranes typically have a three-layer structure (porous support layer, transition and separation layer), asymmetrical distribution, the pore size of 0.8nm ~ 1μm range, precision filter covering microfiltration, ultrafiltration, nanofiltration level .

Depending on the support, the configuration of ceramic membrane can be divided into flat, tubular, multi-channel three. Since the ceramic membrane acid, high temperature and chemical stability under extreme conditions, but also due to the commercialization of the ceramic membrane pore size is small (typically less than 0.2μm), it can be successfully achieved at the molecular level filter, so it is mainly used for liquid, gaseous mixture was separated by filtration, it can replace conventional centrifugal evaporation, distillation, filtration and other separation technologies, to improve product quality, reduce production cost targets, has broad application prospects in the oil and chemical industry and other harsh environments.

It has good chemical stability, acid and alkali resistance to organic solvents conventional polymer membrane material, ceramic membranes compared. Mechanical strength, can be backwashed; strong antimicrobial ability. High temperature; narrow pore size distribution, high separation efficiency advantages in the food industry, biological engineering, environmental engineering, chemical industry, petrochemical industry, metallurgical industry and other fields has been widely used, its market sales of 30% annual growth rate a. The inadequacies of the ceramic membrane is a high cost, an inorganic material brittleness, small elasticity, bring some difficulties to the molding and assembly equipment film and the like.

Ceramic membrane separation principle

Ceramic membrane separation process is a "cross-flow filtration" in the form of a fluid separation process: raw material flow within the liquid high-speed film tube, clarification permeate pressure-driven small molecule-containing component along the direction perpendicular to the outside through the membrane, turbid concentrate was retained by the membrane containing the macromolecular component, so that the fluid reaches separation, concentration, purification purposes.

Ceramic membrane porosity is 30% to 50%, pore size 50nm ~ 15μm ceramic carrier, the sol - gel method asymmetric composite membranes or other processes made of. Structural ceramics for membrane separation is typically a sandwich: the support layer (also known as the carrier layer), transition (also known as the middle layer), film (also known as the separation layer). Wherein the pore size of the support layer is generally 1 ~ 20μm, a porosity of 30% to 65%, the effect is to increase the mechanical strength of the film; pore size smaller than the pore size of the intermediate layer is a support layer, whose role is to prevent the preparation of ceramic stopper layer particles to penetrate the porous support layer, a thickness of about 20 ~ 60μm, a porosity of 30% to 40%; having a separation function layer, pore diameter ranging from 0.8nm ~ 1μm thickness of about 3 ~ 10μm, a porosity of 40% to 55%. Pore size distribution of the entire film is gradually reduced by the supporting layer to layer, forming an asymmetric distribution structure.

According to the ceramic membrane pore size can be divided into microfiltration (pore size greater than 50nm), ultrafiltration (pore size 2 ~ 50nm), nanofiltration (diameter less than 2nm) and other species. When separated, under the action of external forces, small molecules through the membrane, macromolecules retained by the membrane to achieve separation, concentration, purification, to the complex, sterilization and other purposes.