Definition
Homogeneous disperser is a kind of laboratory equipment that processes immiscible or difficult-to-mix material systems (such as liquid-liquid, liquid-solid) into a uniform and stable dispersion state through mechanical action. Its core function is to reduce the particle size of the material, break the aggregates, and promote interphase mixing, resulting in a uniform suspension or emulsion. This equipment is widely used in food, chemical, materials science, environmental monitoring, and other fields for sample preparation, simulating processes, or evaluating formulation stability.
How it works:
Homogenizers mainly use the rotor-stator system to generate strong shear, impact and cavitation effects. When working, the rotor rotating at high speed drives the material to generate axial flow in the closed stator chamber. After the material enters the precise gap between the rotor and the stator, it undergoes the following process: first, the rotor impeller rotates at high speed with the material to generate centrifugal force, so that large particles or droplets are initially dispersed; Subsequently, the material passes through the fine slit of the stator screen hole, and is subjected to strong mechanical shear force and turbulence, and the particle size is further reduced. At the same time, high-speed motion triggers local pressure fluctuations, leading to the formation and rupture of cavitation bubbles, releasing shock waves to break up the microstructure. Finally, the material is continuously processed until the target dispersion is reached.
Measurement method
The effects of a homogenizer are typically quantified by: The particle size distribution can be determined by laser diffraction or dynamic light scattering, reflecting the size range of dispersed solid particles or droplets. Dispersion uniformity can be assessed by post-sampling microscopy or settling tests. Viscosity changes are measured at shear rates using a rotary viscometer to determine changes in the rheological properties of the system. Additionally, dispersion efficiency can be indirectly measured by processing time, energy consumption, and the number of shears required to reach a specific particle size. Operating parameters such as rotor speed (typically expressed in revolutions per minute in rpm), processing time, and sample temperature are recorded to establish a standardized evaluation methodology.
Influencing factors
The homogeneous dispersion effect is affected by the interaction of multiple factors. The nature of the material is fundamental: high-viscosity liquids reduce shear transfer efficiency, while the hardness and initial size of solid particles determine how easy it is to break. The higher the linear speed, the narrower the gap, and the stronger the dispersion force, but it may also generate too much heat and cause the temperature to rise. Prolonged treatment time helps to disperse adequately, but over-treatment may cause reagglomeration. Temperature control is critical, as rising temperatures reduce viscosity and promote dispersion, but exceeding the material's temperature tolerance limit can trigger denaturation or side reactions. In addition, the rotor-stator geometry, such as tooth shape, screen hole diameter and arrangement density, affects the material cycle path and shear frequency.
Applications:
In the food industry, homogenizing dispersers are used for the preparation of emulsification and stabilization of dairy products, condiments or beverages, such as the uniform dispersion of oil-water systems to extend shelf life. In the chemical industry, it is used for pre-dispersion and grinding of pigments, dyes or fillers to improve the color consistency and coating performance of the final product. In materials science research, the device helps disperse nanoparticles such as carbon nanotubes or metal oxides in matrix liquids to construct composites or functional slurries. In environmental monitoring, it can be used for the pretreatment of soil or sediment samples to evenly release pollutants into the extraction solvent and improve the accuracy of analysis and detection.
Key points of selection
The characteristics of the material to be treated are first determined: viscosity range (low to high), solids content, target particle size and whether it can withstand shear heat. The throughput is determined by the size of the device, and the laboratory grade typically processes samples from 1 milliliter to several liters, matching the rotor diameter to the stator clearance range. The speed adjustment range is a key indicator, and the high speed (such as more than 10000 rpm) is suitable for fine dispersion, and the low speed is suitable for starting materials with high viscosity. In terms of material, parts that come into contact with the material should be corrosion-resistant, such as stainless steel 316L, and consider whether pressure resistance or aseptic design is required. In terms of control function, the model with preset speed and time should be selected, and equipped with overheating or overload protection. Finally, the ease of disassembly and maintenance is evaluated: the easy-to-clean disassembly structure helps to avoid cross-contamination of the sample.