Interaction of Moringa oleifera seed protein with a mineral surface and the influence of surfactants.
The paper describes the adsorption of purified protein from seeds of Moringa oleifera to a sapphire interface and the effects of addition of the anionic surfactant sodium dodecylsulfate (SDS) and the cationic surfactant hexadecyltrimethylammonium bromide (CTAB). Neutron reflection was used to determine the structure and composition of interfacial layers adsorbed at the solid/solution interface. The maximum surface excess of protein was found to be about 5.3 mg m(-2). The protein does not desorb from the solid/liquid interface when rinsed with water. Addition of SDS increases the reflectivity indicating co-adsorption. It was observed that CTAB is able to remove the protein from the interface. The distinct differences to the behavior observed previously for the protein at the silica/water interface are identified. The adsorption of the protein to alumina in addition to other surfaces has shown why it is an effective flocculating agent for the range of impurities found in water supplies. The ability to tailor different surface layers in combination with various surfactants also offers the potential for adsorbed protein to be used in separation technologies.
Polytechnic of Namibia, School of Health and Applied Sciences, Private Bag 13388, 13 Storch Street, Windhoek, Namibia. Electronic address: hkwaambwa@polytechnic.edu.na.
Habauka M
HM
Kwaambwa
Materials Physics, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Box 516, 751 20, Uppsala, Sweden.
Maja S
MS
Hellsing
Materials Physics, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Box 516, 751 20, Uppsala, Sweden. Electronic address: Adrian.Rennie@physics.uu.se.
Adrian R
AR
Rennie
Institut Laue Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France.
Robert
R
Barker
D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D029588:Moringa oleifera / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
D002593:Cetrimonium Compounds; D010940:Plant Proteins; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D000537:Aluminum Oxide; D000077286:Cetrimonium
Cetyltrimethylammonium bromide; Moringa oleifera; Neutron reflection; Reflectivity; Sapphire; Seed protein; Sodium dodecylsulfate; Surface excess