Neutralization

The neutralization process is typically used for treating cottonseed oil to remove the majority of degummed oils and gossypol. This oil requires neutralization and requires a low phosphatide content. In the process, free fatty acids are saponified with caustic soda and sodium, depending on the subsequent bleaching method. Afterward, the soap is separated, and the neutralized oil is washed and vacuum dried.

First, we heat the oil to the optimal process temperature. To condition the non-hydratable phosphatides, we add a small amount of concentrated phosphoric acid and blend it thoroughly with the oil. After a brief reaction, we add dilute caustic soda to neutralize the free fatty acids and phosphoric acid. We then process the oil through a separator and into another reaction tank. This step is recommended for oils with high phosphatide content. We use self-cleaning separators to remove the sodium soap.

However, the remaining soap content in the neutral oil is still too high for the next stages. Therefore, we refine the oil through one or two additional washings. To ensure efficiency, we add hot water and mix it with the oil. We then remove the soapy water using an additional separator.

Typically, one wash stage is enough. If small amounts of residual soap remain, a second wash is common. To reduce soap content further, we acidify the wash water with a citric or phosphoric acid solution. Finally, a second caustic treatment may be applied, particularly for crude oil, steam trouble, or lye.

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