Primary aerobic biodegradation of cationic and amphoteric surfactants

The primary aerobic biodegradation of several cationic and amphoteric surfactants has been studied by using the shaking-flask degradation test and orange II spectrophotometric analysis. The results show that cationic and amphoteric surfactants can be readily biodegraded, with their degradation exceeding 94%. The degradation kinetics can be accurately described by the Boltzmann model. The relationship between structure and biodegradability is discussed. The presence of hydrophobic groups has a strong effect on the biodegradability of these surfactants. Biodegradability decreases with increasing chain length. The presence of hydrophilic groups mainly affects the degradation rate of these surfactants, but not their ultimate biodegradeability. Bio-degradability is deterred and degradation is slowed as steric hindrance increases. Degradation rates increase markedly when hydrophilic groups containing an amide bond are pres-ent.