Technological innovation

Characteristics of Microwave Extraction

Fast and efficient

The dipole molecules in samples and solvents produce dipole eddy current, ion conduction and high frequency friction under the action of high frequency microwave energy, thus generating a large amount of heat in a short time. The weak hydrogen bond breakdown and ion migration caused by the rotation of dipole molecules accelerated the penetration of solvent molecules into the sample matrix. The components to be extracted were solvated quickly, which shortened the microwave extraction time significantly.

Uniform heating

Microwave heating by microwave extraction machine is carried out by bulk heating, forming a unique material heating mode, so that the whole sample is heated, without temperature gradient, with the advantages of uniform heating. By eliminating the thermal gradient in the material, the extraction quality is greatly improved and the functional components in food, medicine and other chemical materials are effectively protected.


Because different compounds have different dielectric constants, microwave extraction has the characteristics of selective heating. The higher the polarity of solutes and solvents, the greater the absorption of microwave energy, the faster the temperature rise, and the faster the extraction speed. For non-polar solvents, microwave hardly has heating effect. Therefore, the polarity of solvents must be taken into account in the selection of extractants in order to achieve the best results.

Biological effects (non-thermal properties)

Because most organisms contain polar water molecules, strong polar oscillation is induced under the action of microwave field, which easily leads to hydrogen bond breakdown between cells and molecules, and the breakdown of cell membrane structure by electric breakdown, thus promoting the permeation of matrix and solvation of components to be extracted. In addition, microwave extraction can also achieve time, temperature and pressure control to ensure that organic matter does not decompose in the extraction process. Therefore, when microwave-assisted extraction is used to extract the components from biological matrix, the extraction efficiency can be improved under the synergistic action of thermal and non-thermal effects.

Solvent saving

Compared with other extraction methods, microwave extraction machine can reduce the consumption of extraction reagents. Microwave extraction can extract many samples simultaneously under the same conditions. When used in the production process, the amount of solvent can be reduced by 50%-90% compared with the conventional method.

Simple process and saving investment

Because the microwave extraction machine is an electric equipment, there is no need to equip a boiler; microwave body heating, extraction of the same raw materials, the same efficiency, using conventional methods need two or three times to extract, microwave extraction can be one time. The extraction time is greatly saved and the process flow is greatly simplified. Microwave extraction has no thermal inertia and is easy to control. All parameters can be digitalized, and it is in line with the modernization of pharmaceuticals.

Wide application area

Because of the low extraction temperature, it is not easy to gelatinize, easy to separate and easy to post-process.



Technological process

Microwave-assisted extraction mainly includes material selection, cleaning, crushing, microwave extraction, separation, concentration, drying and other steps to obtain products.

Influence factor

1. Solvent selection

Because different substances have different dielectric constants, the selection of extraction solvent is very important. The following aspects must be considered: (1) Solvents must be transparent or translucent to microwave, and have certain polarity; (2) Solvents have strong solubility to the separated components, but less interference to the follow-up of the extracted components; and (3) Boiling point of the extracted solvent should be higher. The commonly used extraction solvents are n-hexane, dichloromethane, methanol, ethanol and so on.

The extraction solvent has certain polarity, which is the necessary condition for microwave extraction. But if the extraction solvent is non-polar solvent such as toluene and n-hexane, a polar solvent must be added to increase the dielectric constant of the extraction solvent system. At present, the reported solvents are acetone and water. Therefore, the extraction solvent can be a unitary system, a binary system, or a multicomponent system. For a specific sample extraction system, it should be determined according to the nature of the sample, the nature of the extraction target and the pre-experiment.

2.liquid-solid ratio

The liquid-solid ratio is an important factor in the extraction process, which mainly affects the concentration difference between solid phase and liquid phase, i.e. mass transfer impetus. The increase of liquid-solid ratio will inevitably increase the mass transfer impetus to a large extent, but the excessive volume of extraction liquid will increase the burden of subsequent treatment.

3. Microwave radiation time

The time of microwave extraction is related to the amount of sample extracted, the volume of solvent and the heating power. Compared with traditional extraction methods, microwave extraction time is shorter. Generally, 10-15 minutes is enough, sometimes even shorter. For example, when extracting amino acids from food, extraction efficiency does not increase with the extension of extraction time, although continuous irradiation does not cause degradation or destruction of amino acids.

4. Microwave radiation power

Microwave radiation conditions include microwave radiation frequency, power and radiation time, which have a certain effect on extraction efficiency. Different microwave irradiation conditions were used for different extraction purposes.

5. Fragmentation

Like the traditional extraction, the contact area of the extract can be increased after proper crushing, which is conducive to the extraction process. But in general, traditional extraction does not break the material too small, on the one hand, it will increase the dissolution of impurities, on the other hand, it will bring difficulties to subsequent filtration. At the same time, the starch content in the material will be gelatinized and the extract will become viscous at the extraction temperature of nearly 100 C, which increases the difficulty of subsequent separation and the adhesion loss of solvents.

6. Effect of moisture or humidity in materials

Because water can effectively absorb microwave energy and produce temperature difference, the water content in the material to be treated has a great influence on the extraction yield. For non-moisture materials, humidification method can be adopted to make them have appropriate moisture to absorb microwave energy.

7. Other factors affecting microwave extraction (enhancement)

Extraction from solid or semi-solid samples is a complex process, which can be simplified into five steps: 1) desorption of the target from the active point of the material matrix; 2) diffusion of the target to the whole material matrix; 3) dissolution of the target in the extraction solvent; 4) diffusion of the target in the solvent; and 5) collection of the target. Therefore, the effective extraction of the target substance is not only related to the solvent, but also to the properties of the material matrix.


1.Extraction of Organic Pollutants

2.Microwaveextraction machine can be used to extract organic compounds from contaminated soil.

3.Extraction of Natural Compounds and Bioactive Components

4.Microwave assisted extraction of many kinds of compounds from plant raw materials, food, etc.

Any questions of Microwave Extracting Machine please consult us:


WECHAT/WHATSAPP: + 156 2880 2621

SKYPE: Joanna Mu

QQ: 329438797


Contact: Joanna

Phone: + 156 2880 2621

Tel: 0531-82608061


Add: No.2 Wolong Road,Huabei Industrial Zone,Licheng,Jinan,China

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