Question

Surfactants, having both cationic and anionic centres attached to the same molecule, are called:

• A. cationic surfactant
• B. anionic surfactant
• C. zwitter-ionic surfactants
• D. neutral surfactants

Answer 1

Answer: (C)

zwitter-ionic surfactants

Zwitterionic (amphoteric) surfactants have both cationic and anionic centers attached to the same molecule. The cationic part is based on primary, secondary, or tertiary amines or quaternary ammonium cations. The anionic part can be more variable and include sulfonates, as in the sultaines CHAPS (3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate) and cocamidopropyl hydroxysultaine. Betaines such as cocamidopropyl betaine have a carboxylate with the ammonium.