According to decolorization principle, decoloring agent can be roughly divided into three categories: flocculating decoloring agent, oxidizing decoloring agent and adsorption decoloring agent.

The flocculating decoloring agent is a quaternary amine cationic polymer compound that integrates various functions such as decolorization, flocculation, and CODcr degradation.

The oxidizing decoloring agent use oxidizing substances, such as sodium hypochlorite, potassium permanganate, ozone, etc., to destroy colored groups to achieve the purpose of removing chroma.

The adsorption decoloring agent is generally activated carbon, clay or adsorption resin, which can directly filter out impurities and oxides in the oil, which integrates impurity removal, deodorization, decolorization and separation, so that the blackened oil becomeslight-color, transparent liquid, and the acid value and chromaticity of the processed diesel meet the national fuel standards.