Supercritical propylene oxide in plant essential oil extraction of mass transfer efficiency study

In recent years, with the emphasis on green chemistry and environmental protection technology, supercritical fluid extraction technology has been widely concerned in the field of plant essential oil extraction. Among them, supercritical propylene oxide has gradually become a research hotspot because of its excellent physical and chemical properties and environmental protection. In this paper, the mass transfer efficiency of supercritical propylene oxide in plant essential oil extraction will be discussed in depth, and its influencing factors will be analyzed.

What is supercritical propylene oxide?

Supercritical fluid refers to the material whose temperature and pressure are higher than its critical point. At this time, the gas and liquid properties of the material tend to be unified, with high diffusion and solubility. As a cyclic ether, propylene oxide has a low critical temperature and pressure, and is easy to prepare into a supercritical fluid. Compared with traditional organic solvents, supercritical propylene oxide has the advantages of environmental protection, recyclability and high efficiency in the extraction process.

Supercritical Propylene Oxide Extraction Principle

The extraction principle of supercritical propylene oxide is based on its unique physical properties in the supercritical state. In the extraction process, supercritical propylene oxide can effectively dissolve the volatile components in the plant essential oil, and the essential oil is separated from the plant raw material by pressurization and heating. This process does not require the use of organic solvents, avoids the impact on the environment and human health, and is in line with the development direction of green chemistry.

Mass transfer efficiency influencing factors

Mass transfer efficiency is an important index to measure the performance of extraction technology, which directly affects the extraction rate and product quality of essential oils. In extraction with supercritical propylene oxide, the mass transfer efficiency is affected by several factors.

1. Extraction temperature

Temperature is one of the most critical factors affecting mass transfer efficiency. In the supercritical state, the solubility of propylene oxide increases with increasing temperature, thereby improving the extraction efficiency of essential oils. However, an excessively high temperature may lead to decomposition of the target component, so that it is necessary to control the temperature within an appropriate range.

2. Extraction pressure

Pressure is another important parameter for supercritical extraction. Propylene oxide has different physical properties at different pressures, and its density and viscosity increase at higher pressures, which helps to improve mass transfer efficiency. Excessive pressure will increase equipment cost and energy consumption, so it is necessary to optimize the pressure setting.

3. Extraction time

Extraction time directly affects the degree of complete extraction. Under certain temperature and pressure conditions, prolonging the extraction time can improve the extraction rate of essential oil. However, too long time will lead to increased energy consumption, so it is necessary to find the best extraction time.

4. Raw material physical properties

The physical properties of the plant feedstock, such as particle size, density, and porosity, can also affect mass transfer efficiency. Smaller feedstock particles and higher porosity can provide a larger contact area, thereby increasing mass transfer efficiency. Therefore, it is necessary to carry out appropriate pretreatment of the raw material (such as crushing and drying) before extraction.

Strategies for optimizing mass transfer efficiency

In order to further improve the mass transfer efficiency of supercritical propylene oxide in the extraction of plant essential oil, it can be optimized from the following aspects:

1. Optimization of process parameters

According to the analysis of experimental data, the optimal extraction temperature, pressure and time were determined to achieve efficient extraction.

2. Improved extraction equipment

Use high-efficiency extraction equipment design, such as dynamic extraction columns or static extractors, to improve fluid flow uniformity and mass transfer effects.

3. Raw material pretreatment

The extraction efficiency is improved by crushing and drying the raw materials.

4. Fluid dynamics optimization

The flow state of the fluid in the extraction equipment is studied, and the flow rate and flow path are optimized to reduce the mass transfer resistance.

Conclusion

The study of the mass transfer efficiency of supercritical propylene oxide in the extraction of plant essential oils is a complex and important subject. Through in-depth analysis of the effects of extraction temperature, pressure, time and physical properties of raw materials, theoretical support and technical guidance can be provided for practical application. In the future, with the deepening of research and the continuous progress of technology, supercritical propylene oxide will play a greater role in the field of plant essential oil extraction and promote the development of green chemistry.