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Views: 0 Author: Site Editor Publish Time: 2026-04-18 Origin: Site
In the field of membrane separation technology, tubular microfiltration (TMF) membranes have emerged as a pivotal and versatile solution, widely applied in water treatment, chemical industry, food and beverage processing, biotechnology, and many other sectors. Distinguished by their unique tubular structure, excellent filtration performance, and strong adaptability to complex feed streams, TMF membranes have gradually become a core component in modern separation and purification systems, addressing the growing demand for high-efficiency, energy-saving, and environmentally friendly separation technologies worldwide.
Tubular microfiltration is a pressure-driven physical separation process that relies on the sieving effect of membrane pores to separate suspended particles, colloids, microorganisms, and other macromolecular substances from the feed liquid, while allowing water, small-molecule solutes, and ions to pass through freely. The core working principle is based on cross-flow filtration (also known as tangential flow filtration), where the feed liquid flows tangentially along the inner surface of the tubular membrane at a high velocity (typically 1–3 m/s), rather than flowing vertically through the membrane surface (dead-end filtration).
This cross-flow mode generates turbulent flow on the membrane surface, which effectively reduces the accumulation of pollutants and the formation of a cake layer, thereby maintaining stable filtration flux and extending the service life of the membrane. The filtration process is driven by moderate pressure (usually 100–400 kPa or 20–80 psi), and the pressure difference between the inlet and outlet is monitored to adjust the operation parameters in real time. The separated substances are divided into two streams: the permeate (the filtered liquid that passes through the membrane pores) and the retentate (the concentrated liquid containing the intercepted particles), which is discharged from the end of the tubular membrane to ensure continuous operation of the system.
The key mechanism of TMF membranes is physical截留, which is similar to the function of a sieve—particles larger than the membrane pore size are intercepted, while smaller particles and molecules are allowed to pass through. The pore size of TMF membranes is typically in the range of 0.1–10 μm, and the molecular weight of the intercepted macromolecules is generally less than 100,000 g/mol, making it suitable for pre-treatment of other separation processes (such as ultrafiltration and reverse osmosis) or post-treatment of granular media filtration.
TMF membranes are mainly composed of membrane tubes, membrane modules, and supporting structures. The membrane tube is a hollow cylindrical structure, and multiple membrane tubes are usually arranged in parallel and assembled into a membrane module, which can be adjusted according to the treatment scale. The membrane tube has an asymmetric pore structure: the inner surface (separation layer) has small and uniformly distributed pores to ensure filtration precision, while the outer layer (support layer) has a loose and high-porosity structure to optimize filtration flux and mechanical strength.
According to the number of channels, TMF membranes can be divided into single-channel and multi-channel types. The channel diameter of multi-channel membranes is usually between 2 and 16 mm, and the number of channels affects the filtration performance—for example, the increase in the number of channels of hybrid carbon TMF membranes first increases and then decreases the permeation flux and oil rejection, with the optimal performance achieved when the number of channels is 3. The large bore design of TMF membranes allows them to handle feed liquids with high solid content (up to 3–5% by weight), which is an advantage that traditional filtration methods cannot match.
The performance of TMF membranes is closely related to the membrane material, which determines their chemical resistance, mechanical strength, temperature resistance, and anti-pollution performance. Common TMF membrane materials are divided into organic and inorganic categories, each with its own characteristics and application scenarios.
Organic TMF membranes are mainly made of polymer materials such as polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), and polysulfone (PES). These materials have the advantages of good flexibility, easy processing, low cost, and good anti-pollution performance—for example, PVDF membranes have excellent chemical stability and can resist most organic solvents and oxidants, while ultra-high molecular weight PE and PP membranes have high tolerance and can be prepared into high-flux and high-interception membranes through structural regulation technology. Organic TMF membranes are widely used in industrial wastewater treatment, food processing, and other fields due to their excellent comprehensive performance.
Inorganic TMF membranes are mainly made of ceramic materials such as silicon carbide (SiC), aluminum oxide (Al₂O₃), zirconium oxide (ZrO₂), and titanium oxide (TiO₂). They have outstanding advantages such as high mechanical strength, excellent chemical resistance (resistant to strong acids, strong alkalis, and high concentrations of oxidants), high temperature resistance (can operate at temperatures above 100°C), and long service life (up to 5–10 years). For example, SiC TMF membranes have high flux and corrosion resistance, and are suitable for harsh working conditions such as high-temperature and high-corrosion wastewater treatment; ceramic membranes can also be used for oil-water separation and catalyst recovery due to their stable performance.
In addition, some new composite TMF membranes have been developed in recent years, which combine the advantages of organic and inorganic materials—for example, the internal pressure mosaic structure TMF membrane, whose functional separation layer can be designed according to the feed characteristics, and the external support layer is made of modified high-strength materials, achieving a balance between filtration precision and mechanical strength.
Compared with other microfiltration membrane types (such as flat-sheet and hollow fiber membranes), TMF membranes have unique advantages, making them irreplaceable in many application scenarios:
Strong adaptability to feed liquid: TMF membranes can handle feed liquids with high turbidity, high solid content, and high viscosity, and can even process fluids after physical and chemical treatments (such as Fenton and electrocoagulation), without the need for complex pre-treatment processes. The high-velocity cross-flow design effectively prevents membrane clogging, and the membrane can be easily cleaned and restored to its original flux.
Excellent chemical and mechanical stability: Inorganic TMF membranes can resist strong acids, strong alkalis, high temperatures, and oxidants, while organic TMF membranes have good flexibility and impact resistance. Both types can operate stably under harsh working conditions, with a long service life and low maintenance costs.
High filtration precision and stable flux: The uniform pore size distribution of the separation layer ensures high filtration precision, which can effectively intercept particles as small as 0.1 μm, including sediment, algae, protozoa, and large bacteria, meeting the requirements of high-standard filtration. The cross-flow filtration mode maintains stable flux, avoiding the rapid flux decline caused by cake layer accumulation in dead-end filtration.
Easy operation and maintenance: The modular design of TMF membrane modules allows flexible combination according to the treatment scale, which is convenient for installation, replacement, and expansion. The membrane cleaning process is simple, which can be realized by backwashing or chemical cleaning (using acids, alkalis, or oxidants), and the flux recovery rate is high. In addition, TMF systems do not require the addition of polyacrylamide (PAM), reducing treatment costs and environmental risks.
Versatility: TMF membranes can be used for multiple separation purposes such as purification, clarification, sterilization, and concentration, and are widely applicable to various industries, including water treatment, chemical industry, food and beverage, biotechnology, and metalworking.
Benefiting from their excellent performance, TMF membranes have been widely used in various fields, and their application scope is still expanding with the continuous advancement of technology:
Water treatment is the most important application field of TMF membranes, including municipal wastewater treatment, industrial wastewater treatment, drinking water purification, and seawater desalination pre-treatment. In industrial wastewater treatment, TMF membranes are used to treat wastewater from electroplating, semiconductor, aluminum oxidation, surface treatment, and coal chemical industries, effectively removing suspended solids, heavy metals, and organic pollutants, and realizing wastewater recycling or high-standard discharge. For example, in the treatment of electroplating wastewater, TMF membranes can reduce the COD from 400 mg/L to 80 mg/L, and the nickel and copper concentrations to 0.1 mg/L and 0.5 mg/L respectively, meeting the discharge standards.
In drinking water purification, TMF membranes can remove microorganisms, colloids, and suspended particles in raw water, ensuring the safety of drinking water without adding harmful chemicals, and the treated water turbidity is less than 1 NTU, which can directly enter the reverse osmosis (RO) system for deep treatment. In seawater desalination, TMF membranes are used as pre-treatment to remove suspended solids and colloids, preventing the RO membrane from clogging and improving the efficiency and service life of the desalination system.
In the food and beverage industry, TMF membranes are mainly used for clarification, concentration, and sterilization, which can retain the nutritional components of the products while removing impurities, improving product quality and extending shelf life. For example, in fruit juice processing, TMF membranes can remove pulp, suspended particles, and microorganisms, producing clear and transparent fruit juice without affecting the taste and nutritional value; in dairy processing, they are used for whey defatting, protein fractionation, and milk clarification, improving the purity and quality of dairy products. In addition, TMF membranes are also used in the clarification of starch hydrolysates, sugar cane refining, and beer filtration, reducing the use of chemical clarifiers and improving production efficiency.
In biotechnology and pharmaceutical fields, TMF membranes are widely used for cell separation, fermentation broth clarification, protein filtration, and drug purification. For example, in the production of antibiotics, enzymes, and vitamins, TMF membranes can clarify the fermentation broth, remove cell debris and impurities, and improve the purity of the product; in the preparation of high-purity drugs, they can effectively remove suspended particles and microorganisms, ensuring the safety and effectiveness of drugs. The gentle filtration process of TMF membranes can retain the activity of biological substances, avoiding the damage caused by high temperature or chemical treatment, which is crucial for biotechnology and pharmaceutical production.
In the chemical industry, TMF membranes are used for pigment, hydroxide, and catalyst recovery, solvent recovery, dye filtration, and acid-base solution clarification, reducing resource waste and environmental pollution. For example, in the production of pesticides such as glyphosate, TMF membranes can realize nearly zero catalyst loss (recovery rate of 98.5%), reducing the loss of precious metals such as palladium and nickel and the environmental risk of toxic catalysts. In the metalworking industry, TMF membranes are used for degreasing bath recovery, cooling lubricant treatment, and precision part rinse water clarification, realizing the recycling of resources and reducing production costs. In addition, TMF membranes are also used in the treatment of bilge water, vehicle wash water, and textile wastewater, expanding their application scope to more fields.
In recent years, with the continuous development of membrane material technology and separation technology, TMF membranes have made significant progress in material modification, structure optimization, and application expansion. In terms of material research, researchers have developed new high-performance membrane materials, such as ultra-high molecular weight polyethylene and polypropylene TMF membranes with controllable pore structure, which have high flux and high interception performance, and have been industrialized and applied. In terms of structure optimization, the design of multi-channel TMF membranes and composite membrane structures has improved the filtration efficiency and mechanical strength of the membrane, and the development of membrane modules with high automation and intelligent control has reduced operation difficulty and labor costs.
In terms of application innovation, TMF membranes have been successfully applied in new fields such as lithium battery production, wet metallurgy, and coal chemical industry. For example, in the field of lithium battery materials, TMF membranes can improve the direct yield of ternary precursors from 75% to 98%, increase production efficiency by more than 20%, and indirectly promote the energy density of power batteries to increase by more than 10%. In wet metallurgy, TMF membranes are used to extract scarce metals such as cobalt and nickel from wastewater and waste acid, reducing the dependence on imported strategic resources
