Adsorption of a Water Treatment Protein from Moringa oleifera Seeds to a Silicon Oxide Surface Studied by Neutron Reflection

作者：Kwaambwa Habauka M^*; Hellsing Maja; Rennie Adrian R

来源：Langmuir, 2010, 26(6): 3902-3910.

DOI：10.1021/la9031046

An extract from the seeds of the Moringa oleifera tree that is principally a low molecular mass protein is known to be efficient as a coagulating agent for water treatment. The present paper investigates the adsorption of the purified protein to silica interfaces in order to elucidate the mechanism of its function as a flocculent. Neutron reflection permits the determination of the structure and composition of interfacial layers at the solid/solution interface. Dense layers of protein with about 5.5 mg m(-2) were found at concentrations above 0.025% wt. The overall thickness with a dense layer in excess of 60 angstrom at 0.05 wt % suggests strong co-operative binding rather than single isolated molecules. All ionic surfactant, sodium dodecyl sulfate, was also seen to coadsorb. This strong adsorption of protein in combination with the tendency for the protein to associate suggests a mechanism for destabilizing particulate dispersions to provide filterable water. This call occur even for the protein that has previously been identified as being of low mass (about 7 kDaltons) and thus is unlikely to be efficient in bridging or depletion flocculation.

• 出版日期2010-3-16