Conventional metal degreasing powder is mainly composed of alkali metal hydroxide, carbonate, phosphate or polyphosphate, ethylenediamine tetraacetate (EDTA), various surfactants which play the roles of penetration, emulsification and dispersion. Alkaline metal hydroxide plays the role of saponification and degreasing, and phosphorus-rich compounds such as carbonate, phosphate or polyphosphate have excellent properties. Excellent degreasing, corrosion inhibition and complexation ability. Nitrogen-rich compounds of EDTA have excellent chelating ability. Aromatic ring-containing surfactants, such as alkyl benzene sulfonate and alkyl phenol polyoxyethylene ether, which are difficult to biodegrade, are also widely used in degreasing powder because of their low cost and good degreasing effect. Because these substances contain high phosphorus and nitrogen, etc. Eutrophic substances contain surfactants that are not easily biodegradable, and long-term use has caused serious environmental pollution to the ecological environment.

Common substances in alkaline degreasers containing surfactants are as follows:

1) Sodium hydroxide, also known as caustic sodium, is a strong alkali compound. It dissolves in water and ionizes, provides alkalinity, and saponifies with animal and vegetable oils to form glycerol and fatty acid salts that can dissolve in water and disperse in aqueous solution.

2) Sodium carbonate, also known as soda, is a low-cost alkali, which produces HO-1 when hydrolyzed in water to provide basicity. Therefore, sodium carbonate has a buffer effect and does not corrode some non-ferrous metals like strong alkali.

3) Trisodium phosphate, a few condensated phosphate trisodium phosphate, produces phosphoric acid with little dissociation during hydrolysis, thus obtaining basicity. Trisodium phosphate has the function of softening hard water and obviously promoting the dispersion (emulsification) of fouling particles. It also has higher alkalinity and can dissolve fatty fouling through saponification.

4) Sodium silicate has sodium orthosilicate, sodium metasilicate and sodium silicate. Sodium silicate can form stable colloids and solvated micelles in water. When used together with surfactants, it has good washing aid. Silicate hydrolysis occurs in water, the silicic acid produced by hydrolysis is insoluble in water, and suspended in the tank with micelle structure. This solvated micelle has the ability to suspend and disperse the particles of solid dirt and emulsify the oil dirt, so it is helpful to prevent the re-deposition of dirt on the surface of the workpiece.

5) surfactants

Anions: sodium oleate, triethanolamine oleate, sodium stearate, sodium dodecyl sulfate, sulfonated castor oil, sodium alkyl ether sulfate, sodium dodecyl benzene sulfonate, ammonium alkyl benzene sulfonate, sodium methoxy fatty amide benzene sulfonate, sodium dodecyl alcohol amide phosphate, sodium N, N-monooleoyl methyl taurine, etc. Non-ionic: aliphatic alcohol polyoxyethylene ether, alkyl phenol polyoxyethylene ether, lauryl diethanolamide, etc.

6) corrosion inhibitor

Organic amines: Organic amines, amides, etc., such as oleoyl sarcosine salt, benzotriazole, 2-mercaptobenzothiazole, imidazoline compounds, alkyl pyridinium chloride, and others: sodium nitrite, sodium nitrate, phosphate, sodium silicate, sodium benzoate, chromate, etc.