Surface tension in acids and alkali

The outstanding chemical stability of fluorinated surfactants to strong acids and alkali permits their use under conditions in which conventional surfactants would decompose. Certain fluorinated surfactants can be used in the presence of strong oxidants, acids, or alkalies even at elevated temperatures. 

The surface tension of Zonyl fluorinated surfactants, featuring the hydrophobe F(CF2CF2)3-gCH2CH2—, in acids and alkali is shown in Table 4.8. Anionic, cationic, nonionic, or amphoteric surfactants listed in Table 4.8 can lower the surface tension of 10% potassium hydroxide, 25% sulfuric acid, 37% hy- 

Zonyl 10% Potassium hydroxide 25% Sulfuric acid 37% Hydrochloric acid 70% Nitric Acid  

The surface tensions of some perfluorinated anionic surfactants with a CsFi7— hydrophobe in strong acids are given in Table 4.9 [56]. The surfactant CgFivSOsK is very effective in concentrated acids, although its solubility in 37% hydrochloric acid is limited to 0.2 g/L. 

The surface tension of the tetraethylaramonium salt of the perfluorinated surfactant CgFi7S03N(C2H5)4 in acids is shown in Figs. 4.30 and 4.31 [49]. 

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