Homogenization is the process of breaking up the solid particles in the liquid material to make the solid particles ultra-fine and forming a uniform suspended emulsion. Homogenization technology is already a very important fine dispersion technology, which is widely used in the dairy, beverage, food, cosmetics and chemical industries. In pharmaceutics, the smaller the drug particles, the more it helps to improve the dissolution rate and solubility of the drug, which is conducive to improving the bioavailability of poorly soluble drugsIt is also beneficial to improve the dispersion of the drug in the dispersion medium.
1. High-pressure homogenization technology: under high pressure, the material undergoes a series of changes in physical, chemical, and structural properties, and finally achieves the effect of homogenization.
2. Shear homogenization technology: the dynamic stator rotor and double rotor structure are used to realize the ultra-refinement of materials.
3. Micro-jet homogenization technology: the liquid material is formed at high pressure to form a high-speed jet, and another jet in the opposite direction forms a high-speed collision, so that the solid material in it is ultra-refined.
The force of the homogenizer is mainly for:Shear forces and pressures。During the homogenization process, a laminar flow effect is generated, in which dispersed phase particles or droplets are sheared and elongated and crushedAffected by the turbulence effect, particles or droplets are randomly deformed under pressure fluctuations;Affected by the cavitation effect, the high pressure action causes the small bubbles to burst quickly, releasing energy, which causes local hydraulic shocks and vibrations.
The liquid passing through the gap is ejected at an extremely high speed due to the instantaneous loss of pressure, and hits the homogeneous part, resulting in three effects: shear, impact, and cavitation.
Liquids at higher velocities flow through the gaps in the homogenizing chamber due to the large velocity gradients, resulting in a violent shear effect. The dispersed phase particles or droplets will be deformed under the action of strong shear force, and when the shear force is large to a certain extent, the droplets in the dispersed phase will be broken.
As the liquid flows through the gap, it hits the impact ring at an extremely high velocity, causing the droplets to break.
As the liquid flows through the gap in the homogenizing chamber valve at a high velocity, a significant pressure drop is formed. When the pressure is reduced to the saturated vapor pressure of the liquid, the liquid begins to boil and undergoes extremely rapid vaporization, forming a large number of bubbles. As the liquid flows out of the homogenization valve, the pressure increases rapidly, causing the bubbles to burst suddenly, instantly forming a large number of cavities. The holes will release a large amount of energy, forming high-frequency vibrations that will break the droplets.
In the microfluidic flow field in the homogeneous cavity, pressure and fluid velocity are important parameters to determine the magnitude of the cavitation effect. The hole effect is described by the cavitation number. Cavitation occurs when cavitation number 1, and the smaller it is, the stronger the cavitation effect.
Where: the recovery pressure of the liquid;Vapor pressure;Density of liquid;The average velocity at the gap of the liquid.
High-pressure homogenizerThe process of extruding, extending, impacting and crushing liquid materials by applying high pressure to the pressure device mainly relies on cavitation effect and turbulence effect. The advantage is that it is relatively low. It is suitable for flexible and semi-flexible granular materials.
High shear machineThe high shear effect generated by the relatively high-speed movement between the stator and rotor causes the material to shear, tear and mix. At the same time, the strong cavitation action disperses, refines and homogenizes the material particles. The advantages are large processing capacity, good stability, durable and easy maintenance of the equipment.
Microfluidic homogenizerThe nozzle of about tens to hundreds of microns is used to form a supersonic jet, which collides with each other and extremely strong shear, and produces a good particle size distribution effect at a high homogenization pressure. The advantage is that it can be operated continuously under high pressure conditions.
The cavitation effect and turbulence caused by high-pressure fluids are mainly based on the high shear force generated by the relative motion between the rotors, accompanied by the cavitation effect, the supersonic jets collide with each other for a very strong shear homogenization effect, the homogeneous particle size is small, the homogeneous particle size is less than 1 m, the stability is good, the mixing, sterilization and homogenization can be completed at the same time, the higher homogenization pressure and better particle size distribution effect can be completed at the same time, and the particle size can reach within 100 nm.
After the material flows through the check valve, it is pressurized in the high-pressure chamber pump, and through the micron-level nozzle, it hits the emulsification chamber at high speed, and through strong cavitation, collision and shear effect, a small and uniform particle size distribution is obtained sufficiently. Its key indicators are as follows:
In the homogenization process, whether the homogenization pressure required by the material can be stably reached is the main factor in the selection of the homogenizer.
The processing flow rate of the equipment is related to factors such as equipment selection, homogenization pressure, material viscosity or concentration, etc.
For many temperature-sensitive and temperature-influencing materials, whether the equipment can monitor the temperature of the incoming and outgoing materials (inlet temperature, outlet temperature) in real time, and whether the temperature control effect of the condenser tube can meet the needs are the selection indicators that cannot be ignored.
In the selection of production equipment, continuous working capacity is also a very important selection factor.
Microfluidic homogenizerCoreThe fixed geometry of the component, which has a direct effect on the finished product. Now the homogenization cavity with "Y" or "Z" structure is basically adopted.
Y" type homogenizing cavity, the material fluid is divided into two thin streams in the acceleration process, and after the head-on collision and mixing through the microtubule channel, the collision force itself is relatively soft when the relative speed of binding is obtained, which is conducive to mixing and emulsification.
The high shear force of the material flow through the microtubule channel at high speed first reduces its own particle size, and then the high collision force generated by it with the inner wall of the homogenization cavity further deagglomerates and loosens the material, which is conducive to reducing the particle size distribution, deagglomerating and dispersion.
Reference[1] Dong Shu. Numerical simulation and experimental study of the effect of high-pressure microfluidics parameters on homogenization performance[D].Qilu University of Technology. [2] Li Cunhong, Hou Yan, Fu Dexue. Comparison of high-pressure homogenization, high-shear emulsification, and microfluidic homogenization and their application in food[J].Journal of Jiaozuo University, 2020[3] Wu Xue, Liu Bin, Feng Tao. Analysis of ultrafine grinding mechanism of microfluidic homogenizer[J].Food & Machinery, 2009(3):4