Interactions in Aqueous Solution of a Zwitterionic Surfactant with a Water Treatment Protein from Moringa oleifera Seeds Studied by Surface Tension and Ultrasonic Velocity Measurements*

Abstract

The interaction of a zwitterionic surfactant with the water treatment protein extracted from Moringa oleifera has been investigated by surface tension and ultrasonic velocity measurements. The critical micelle concentration (CMC) of zwitterionic surfactant was determined to be 2. 4 ± 0.3 mM by both techniques and the partial specific volume ν = 0.78 ± 0.06 cm 3 /g for the protein was found . There seems to be a mild interaction between the protein and the surfactant as shown by surface tension measurements. The ultrasonic velocity was found to decrease in the vicinity of the critical mi celle concentration which may be due to micelle aggregates formation and the protein caused a shift of the surfactant’s CMC to a higher concentration.