Solvent extraction is a common method for extracting vegetable oil. Its principle is to dissolve the oil in plant raw materials by solvent, and then separate the oil by evaporating the solvent, thus obtaining pure vegetable oil. This method is suitable for all kinds of plant raw materials, including soybeans, peanuts, cottonseeds, rapeseeds and so on.

The principle of solvent extraction method mainly includes the following steps:

1. Raw material treatment: firstly, plant raw materials need to be crushed or broken to increase their surface area, which is beneficial to the penetration of solvents and the dissolution of oil.

2. Solvent extraction: the treated plant raw materials are mixed with the solvent, so that the solvent can fully penetrate into the raw materials and dissolve the oil. Commonly used solvents include n-hexane and ethanol.

3. Solvent evaporation: the solution containing grease is evaporated to evaporate the solvent, thus obtaining the concentrated solution of grease.

4. Oil separation: Oil is separated from solvent by distillation or other methods to obtain pure vegetable oil.

The advantage of solvent extraction method is that it can extract most of the oil from plant raw materials with high extraction rate; At the same time, it can be applied to various kinds of plant raw materials. However, due to the use of chemical solvents, it causes certain pollution to the environment, and there are certain security risks in the process of solvent evaporation, so it is necessary to strictly control the operating conditions in actual production to ensure safe production.

In addition, in order to reduce the impact on the environment, in recent years, there have also been some research and applications of solvent-free or low-solvent extraction methods, which can reduce the impact on the environment by improving the process conditions or using alternative solvents. The emergence of these new technologies provides a more environmentally friendly and sustainable choice for vegetable oil production.

In a word, as a common method of extracting vegetable oil, solvent extraction method should choose appropriate process conditions and solvent types according to specific conditions in actual production to ensure production efficiency and product quality while minimizing the impact on the environment.